Research on Passivity Based Controller of Three Phase Voltage Source PWM Rectifier
Directory of Open Access Journals (Sweden)
Yin Hongren
2012-09-01
Full Text Available Euler-Lagrange (EL model of voltage source PWM rectifier is set up based on its model in synchronous dq coordinates. Passivity based controller is designed on the basis of passivity and EL model of voltage source PWM rectifier. Three switching function are educed by passivity based controller. A switching function is only realized in engineering consequently. Voltage source PWM rectifier using passivity based controller has many advantages, such as simpler structure, low total harmonic distortion, and good disturbance rejection performance. Passivity based control law is proved feasible by simulink simulation.
Tanaka, Toshihiko; Funabiki, Shigeyuki; Nakazato, Masafumi
This paper introduces a new approach to the capacitor-commutated converters (CCCs) for HVDC systems. A small-rated three-phase voltage-source PWM converter is connected between a series commutation capacitor and thyristor converter through matching transformers. The PWM converter acts as auxiliary commutation-capacitor for the thyristor converter while the series passive capacitor acts as the main commutation capacitor. The capacitance, which is the sum of the small-rated active and series passive capacitors, is variable, so that stable commutation is obtained. In CCCs commutation failure occurs when the ac bus voltage is recovered whereas the proposed combined commutation-capacitor can achieve successful commutation for both rapidly decreasing and increasing ac bus voltages. The basic principle of the proposed active-passive capacitor commutated converter is discussed in detail. Then, constant margin-angle control with a constant firing angle of the thyristor converter is proposed using a function generator block. Digital simulation demonstrates the novelty and effectiveness of the proposed active-passive capacitor commutated converter.
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IONESCU Andrei
2013-05-01
Full Text Available This paper presents an appropriate methodto limit the switching frequency for a currentcontrolledvoltage-source PWM inverter. The currentcontrolledPWM strategy with carrier wave is based onclassical hysteresis control. The fictional hysteresisband is given by the amplitude of the triangular carrierwave, which is added to the reference signal. The errorbetween the reference current signal with carrier waveand current feedback signal determines the PWMswitching instants. In order to eliminate the unwantedhigh switching frequencies, a mathematical expressionhas been proposed based on graphical analysis. Themethod validation is illustrated by means of simulationin programming and simulation environmentMATLAB Simulink®. Moreover a comparison betweenthe proposed current-controlled PWM strategy withcarrier wave and the open loop voltage-controlledPWM strategy with synchronized triangular carrierwaveis made from point of view of harmonicdistortions.
Directory of Open Access Journals (Sweden)
S. Manivannan, S. Veerakuma
2014-01-01
Full Text Available The Three Phase Voltage Source Inverter supplies invariably required variable voltage and frequency of the adjustable speed drive system. A number of pulse width modulation (PWM schemes are used to obtain variable voltage and frequency supply from an inverter. The most widely used PWM scheme for a Three Phase Voltage Source Inverter is carrier based sinusoidal PWM and Space Vector Pulse Width Modulation (SVPWM. There is an increasing trend of using SVPWM, because of their easier digital realization and better DC bus utilization. The study of SVPWM technique reveals that this technique utilizes DC bus voltage more efficiently and generates less harmonic distortion when compared with sinusoidal PWM techniques. The SVPWM technique has become one of the important PWM technique for Three Phase Voltage Source Inverter for the control of AC induction motor, Brushless DC motor, Switched Reluctance motor and Permanent Magnet Synchronous motor. In this paper having collection of different schemes in SVPWM. Specifically various schemes are Center aligned two level SVPWM, Level shifted multi-carrier concepts based SVPWM, and Third order harmonic injection based modulated reference waveform generation and comparison in SVPWM. This paper having simulation results of all the three schemes of SVPWM by using MATLAB/SIMULINK software. The performance of Three Phase Voltage Source Inverter fed induction motor drive based on various SVPWM schemes are analyzed by various reference parameters like DC bus utilization, Total harmonic distortion (THD, switching stress and efficiency. As a result of these analysis this paper recommends which scheme is more suitable for variable voltage and various frequency drives. The simulation results are provided to validate the proposed model approaches.
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Zulkifilie Bin Ibrahim
2014-03-01
Full Text Available Pulse width modulation (PWM technique is one of the vital issues for power electronic circuit control. A number of Pulse width modulation (PWM techniques are increasingly applied in many new industrial applications that require superior performance. The most widely applied PWM technique for three-phase voltage source inverters are Sine Pulse Width Modulation (SPWM, Third Harmonic Injection Pulse Width Modulation (THIPWM and Space Vector Pulse Width Modulation (SVPWM. SPWM is the most simple modulation technique that can realize easily in analog circuit. However, it has some drawbacks such as higher total harmonic distortion (THD, lower switching frequency and not capable in over modulation region. THIPWM and SVPWM both provide better THD compared to SPWM. SVPWM shows lower THD in over modulation region and in high frequency application compared to THIPWM. These three techniques are discussed, analyzed and compared in terms of modulation index, switching frequency and inverter input voltage in this paper. The modeling and simulation for all PWM techniques have been done by using MATLAB/SIMULINK and Origin 6.1. From the simulation results, SVPWM shows the best performance and meet IEEE 519 standard of current harmonics level.
Miller, Stephanie Katherine Teixeira
Of all the alternative and renewable energy sources, wind power is the fastest growing alternative energy source with a total worldwide capacity of over 93 GW as of the end of 2007. However, making wind energy a sustainable and reliable source of electricity doesn't come without its set of challenges. As the wind turbines increase in size and turbine technology moves towards off-shore wind farms and direct drive transmission, the need for a reliable and efficient power electronics interface to convert the variable-frequency variable-magnitude output of the wind turbine's generator into the fixed-frequency fixed-magnitude voltage of the utility grid is critical. This dissertation investigates a power electronics interface envisioned to operate with an induction generator-based variable-speed wind turbine. The research conclusions and the interface itself are applicable to a variety of applications, including uninterruptible power supplies, industrial drives, and power quality applications, among others. The three-phase PWM rectifiers with ac-side bidirectional switches are proposed as the rectification stage of the power electronics interface. Modulation strategies are proposed for the rectifiers and the operation of the rectifiers in conjunction with an induction generator is demonstrated. The viability of using these rectifiers in place of the standard three-phase voltage-source converter is analyzed by comparing losses and common-mode voltage generation of the two topologies. Parallel three-phase voltage-source converter modules operated in an interleaved fashion are proposed for the inversion stage of the power electronics interface. The interleaved three-phase voltage-source converters are analyzed by deriving analytical models for the common-mode voltage, ac phase current, and dc-link current to reveal their spectra and the harmonic cancellation effects of interleaving. The practical problem of low frequency circulating current in parallel voltage-source converters is also analyzed. The low frequency circulating current characteristics of abc, dq, and nonlinear average current control are determined and experimental results for the nonlinear average current control are presented.
Novel Three-Phase Current-Regulated Digital PWM and its Behavioral Analysis
Ohshima, Masaaki; Masada, Eisuke
With respect to PWM algorithm for a three-phase voltage-source ac/dc power converter various studies have been executed and their results have been published since the analog modulation scheme based on triangular carrier wave was proposed in 1960's. PWM algorithm can be considered the heart of the electronic power conversion. Along with progress and evolution of digital technology gate signals are increasingly requested to be generated directly by digital IC, e.g. MPU, DSP or FPGA/CPLD. The paper analyzes quantitatively the precision of the current controllability of digital PWM taking into account of both the sampling period and the delay time the latter of which is inevitably accompanied by digital procedure. The delay time is pointed out to affect the current error double. In addition the paper derives theoretically the condition for digital PWM to accomplish PPCR (Pulse Polarity Consistency Rule, i.e. the next gate command moves only to the adjacent ones). In so far as the authors know no paper offers the mathematical requirements to execute PPCR taking account of the effect by the delay time with digital PWM. The derived theoretical results are summarized as the digital PWM design criteria for a three-phase PWM converter in order to facilitate practical implementation of the theory, which guarantee the PPCR behavior as well as the quantitative preciseness of the current regulation.
Shunt PWM advanced var compensators based on voltage source inverters for Facts applications
Energy Technology Data Exchange (ETDEWEB)
Barbosa, Pedro G.; Misaka, Isamu; Watanabe, Edson H. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia
1994-12-31
Increased attention has been given to improving power system operation. This paper presents modeling, analysis and design of reactive shunt power compensators based on PWM-Voltage Source Inverters (Pulse Width Modulation -Voltage Source Inverters). (Pulse Width Modulation - Voltage Source Inverters). The control algorithm is based on new concepts of instantaneous active and reactive power theory. The objective is to show that with a small capacitor in the side of a 3-phase PWM-VSI it is possible to synthesize a variable reactive (capacitive or inductive) device. Design procedures and experimental results are presented. The feasibility of this method was verified by digital simulations and measurements on a small scale model. (author) 9 refs., 12 figs.
A Novel PWM Scheme for a Three-Level Voltage Source Inverter Fed Induction Motor
Directory of Open Access Journals (Sweden)
J. Amarnath
2009-03-01
Full Text Available This paper presents a space vector PWM scheme for a three level GTO voltage source inverter fed induction motor. This SVPWM method provides high safety voltages with less harmonic components compared to two level structures and reduces the switching losses by limiting the switching to the two thirds of the pulse duty cycle. The principle of SVPWM method and voltage vector selection procedure for two level and three level inverters are described in detail. The theoretical study was numerically simulated and high power and high voltage three-level GTO inverters applied to induction motors drives.
An Integrated Inductor For Parallel Interleaved Three-Phase Voltage Source Converters
DEFF Research Database (Denmark)
Gohil, Ghanshyamsinh Vijaysinh; Bede, Lorand
2015-01-01
Three phase Voltage Source Converters (VSCs) are often connected in parallel to realize high current output converter system. The harmonic quality of the resultant switched output voltage can be improved by interleaving the carrier signals of these parallel connected VSCs. As a result, the line current filtering requirement can be reduced. However, an additional inductive filter is required to suppress the circulating current. The integrated inductive component, which combines the functionality of the line filter inductor and the circulating current inductor is presented in this paper. An analysis of the flux density distribution in the integrated inductor is presented and design procedure is described. The analysis has been also verified by performing finite element analysis. The advantage offered by the use of the integrated inductor is demonstrated by comparing its volume with the volume of the state-of-the-art filtering solution. The performance of the integrated inductor is also verified by the experimental measurements.
Analysis of Discontinuous Space Vector PWM Techniques for a Seven-Phase Voltage Source Inverter
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Mohd. Arif Khan
2012-03-01
Full Text Available This paper presents discontinuous space vector PWM (DPWM techniques for a seven-phase voltage source inverter (VSI. Space vector model of a seven-phase VSI shows that there exist 128 space vectors with different lengths and maps into fourteen sided polygons. A number of possibilities could arise to implement modulation of inverter legs due to large number of available space voltage vectors. Two strategies are adopted here; one utilising large and two middle sets of space vectors to implement discontinuous space vector PWM. Clamping of legs of inverter to either positive or negative dc bus leads to discontinuity in the switching and consequently offers reduced switching loss modulation strategy. A significant reduction in switching losses can be achieved while employing DPWM in a seven-phase VSI. A generalised method is also proposed to realize the DPWM in a seven-phase VSI. Comparison of continuous and discontinuous PWM is presented in terms of switching current ripple. The experimental set-up is illustrated and the experimental results are presented.
Vasquez, Juan Carlos; Guerrero, Josep M.; Savaghebi, Mehdi; TEODORESCU, Remus
2011-01-01
Power electronics based microgrids consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of three-phase VSIs are derived. The proposed voltage and current inner control loops and the mathematical models of the VSIs were based on the stationary reference frame. A hierarchical control for the paralleled VSI system was developed based on three levels. The primary control includes the droop method and the ...
Vasquez, Juan Carlos; Guerrero, Josep M.; Savaghebi, Mehdi; Eloy-Garcia, Joaquin; TEODORESCU, Remus
2013-01-01
Power electronics based MicroGrids consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of parallel connected three-phase VSIs are derived. The proposed voltage and current inner control loops and the mathematical models of the VSIs are based on the stationary reference frame. A hierarchical control scheme for the paralleled VSI system is developed comprising two levels. The primary control includes t...
Analysis of Peak-to-Peak Current Ripple Amplitude in Seven-Phase PWM Voltage Source Inverters
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Gabriele Grandi
2013-08-01
Full Text Available Multiphase systems are nowadays considered for various industrial applications. Numerous pulse width modulation (PWM schemes for multiphase voltage source inverters with sinusoidal outputs have been developed, but no detailed analysis of the impact of these modulation schemes on the output peak-to-peak current ripple amplitude has been reported. Determination of current ripple in multiphase PWM voltage source inverters is important for both design and control purposes. This paper gives the complete analysis of the peak-to-peak current ripple distribution over a fundamental period for multiphase inverters, with particular reference to seven-phase VSIs. In particular, peak-to-peak current ripple amplitude is analytically determined as a function of the modulation index, and a simplified expression to get its maximum value is carried out. Although reference is made to the centered symmetrical PWM, being the most simple and effective solution to maximize the DC bus utilization, leading to a nearly-optimal modulation to minimize the RMS of the current ripple, the analysis can be readily extended to either discontinuous or asymmetrical modulations, both carrier-based and space vector PWM. A similar approach can be usefully applied to any phase number. The analytical developments for all different sub-cases are verified by numerical simulations.
Control Method Compensating for Unbalanced Three-Phase Voltage Supply in Voltage Source Inverter.
Czech Academy of Sciences Publication Activity Database
Chomát, Miroslav; Schreier, Lud?k; Bendl, Ji?í
Sydney : The University of Newcastle Australia, 2004, s. 523-527. [Symposium IFAC (International Federation of Automatic Control) on Mechatronic Systems /3./. Sydney (AU), 06.09.2004-08.09.2004] R&D Projects: GA ?R GA102/02/0554 Keywords : voltage source inverter * unbalanced voltage supply * pulse width modulation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Three-Phase Voltage Source Inverter with Compensation of Unbalanced Voltage Supply.
Czech Academy of Sciences Publication Activity Database
Chomát, Miroslav; Schreier, Lud?k; Bendl, Ji?í
Tokyo : Institute of Electrical Engineers of Japan, 2005, s. 2038-2041. ISBN 4-88686-065-6. [International Power Electronic Conference IPEC-Niigata 2005. Toki Messe, Niigata (JP), 04.04.2005-08.04.2005] R&D Projects: GA ?R(CZ) GA102/04/0215 Institutional research plan: CEZ:AV0Z20570509 Keywords : unbalanced voltage supply * voltage source inverter * pulse width modulation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Modulation Index Effect on the 5-Level SHE-PWM Voltage Source Inverter
Hassan Feshki Farahani
2011-01-01
Harmonic content of the voltage source inverters is important and must be in the allowed ranges. Different method are proposed to decrease the Total Harmonic Distortion (THD) and caused to be sinusoidal the output voltage of inverters. One of these methods is using multilevel structure. In this structure many important parameters which are effective on voltage source inverter operation that among them we can mention to modulation index (MI). Variation of modulation index can change the THD. O...
Intelligent Optimize Design of LCL Filter for Three-Phase Voltage-Source PWM Rectifier
DEFF Research Database (Denmark)
Sun, Wei; Chen, Zhe
2009-01-01
Compared to traditional L filter, a LCL filter is more effective on reducing harmonic distortion at switch frequency. So it is important to choose the LCL filter parameters to achieve good filtering effect. This paper introduces some traditional design methods. Design of a LCL filter by genetic algorithm (GA) and particle swam optimization (PSO) are presented in this paper and comparison of the two intelligent optimization. Simulation result and calculate data are provided to prove that intelligent optimization are more effective and simple than traditional methods.
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Zhongjiu Zheng
2011-08-01
Full Text Available The paper describes a microcomputer control system, which uses the floating-point digital signal processor TMS320LF2407 from Texas Instruments, for three-phase PWM rectifier. It could effectively eliminate harmonic distortion of line currents and provides power factor correction. Moreover, it can be save electrical energy and reduction of production cost. In the control system, the predictive current control in two-dimensional (?-? stationary frame, makes the input current following the phase voltage in phase to get unity power factor; and space vector pulse wide modulation (SVPWM generates the modulation wave. Finally, the three-phase PWM rectifier using the proposed control system is designed in Simulink/Matlab and executed in laboratory prototype, and the results are provided to verify the proposed control system in the end of the paper.
Microcontroller based PWM controlled four switch three phase inverter fed induction motor drive
Mohanty Kant Nalin; Muthu Ranganath
2010-01-01
This paper presents PIC microcontroller based PWM inverter controlled four switch three phase inverter (FSTPI) fed Induction Motor drive. The advantage of this inverter that uses of 4 switches instead of conventional 6 switches is lesser switching losses, lower electromagnetic interference (EMI), less complexity of control algorithms and reduced interface circuits. Simulation and experimental work are carried out and results presented to demonstrate the feasibility of the proposed approach. S...
DEFF Research Database (Denmark)
Vasquez, Juan Carlos; Guerrero, Josep M.
2011-01-01
Power electronics based microgrids consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of three-phase VSIs are derived. The proposed voltage and current inner control loops and the mathematical models of the VSIs were based on the stationary reference frame. A hierarchical control for the paralleled VSI system was developed based on three levels. The primary control includes the droop method and the virtual impedance loops, in order to share active and reactive power. The secondary control restores the frequency and amplitude deviations produced by the primary control. And the tertiary control regulates the power flow between the grid and the microgrid. Also, a synchronization algorithm is presented in order to connect the microgrid to the grid. The evaluation of the hierarchical control is presented and discussed. Experimental results are provided to validate the performance and robustness of the VSIs functionality during Islanded and grid-connected operations, allowing a seamless transition between these modes through control hierarchies by regulating frequency and voltage, main-grid interactivity, and to manage power flows between the main grid and the VSIs.
Microcontroller based PWM Inverter for Speed Control of a Three Phase Induction Motor
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M. A. Latif
2013-04-01
Full Text Available Three phase induction motor has proven to be an extremely reliable electromechanical energy conversion device for over 100 years. The speed control of induction motor is a crying need for the real world industrial applications. However, there are so many options available for the precise speed control of induction motor except by changingthe frequency. Therefore to achieve the goal of speed control of induction motor, there is no alternative of inverters. With the availability of high speed power semiconductor devices, the three phase inverters play the key role for variable speed ac motor drives. In addition to the speed control, the inverter can also provide some unique features, like voltage control, torque control, power factor correction, auto breaking, built in protection system and so forth.In this paper, a three phases PWM inverter using MC3PHAC microcontroller with computer interface is proposed to run a squirrel case induction motor. Some results of the proposed inverter are presented.
Microcontroller based PWM controlled four switch three phase inverter fed induction motor drive
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Mohanty Kant Nalin
2010-01-01
Full Text Available This paper presents PIC microcontroller based PWM inverter controlled four switch three phase inverter (FSTPI fed Induction Motor drive. The advantage of this inverter that uses of 4 switches instead of conventional 6 switches is lesser switching losses, lower electromagnetic interference (EMI, less complexity of control algorithms and reduced interface circuits. Simulation and experimental work are carried out and results presented to demonstrate the feasibility of the proposed approach. Simulation is carried out using MATLAB SIMULINK and in the experimental work a prototype model is built to verify the simulation results. PIC microcontroller (PIC 16F877A is used to generate the PWM pulses for FSTPI to drive the 0.5 hp 3-phase Induction Motor.
Three Phase Six-Switch PWM Buck Rectifier with Power Factor Improvement
DEFF Research Database (Denmark)
Zafar Ullah Khan, M; Mohsin Naveed, M.
2013-01-01
Conventional Phase Controlled Rectifier injects low order current harmonics into the AC mains. Large size filtering components are required to attenuate these harmonics. In this paper, Three Phase Six-Switch PWM Buck Rectifier[1] is presented which operates at nearly unity power factor and provides variable output voltage. Small size energy storing components are required depending upon switching frequency. MATLAB simulation is performed and modified Sinusoidal Pulse Width Modulation(SPWM) switching technique is used in 3kW prototype converter to demonstrate low input current THD, nearly unity displacement factor, well regulated output voltage and reduced switching losses compared to conventional SPWM.
Kalyanraj, D.; Lenin Prakash, S.
2014-01-01
A constant frequency hysteresis current control technique for a three-phase voltage source inverter (VSI) has been developed for AC drives, power quality and renewable energy applications. This paper presents a digital implementation of a constant frequency hysteresis current control technique for a three-phase VSI feeding an inductive load, using digital signal controller TMS320F2812. The limitations of variable frequency hysteresis control have been discussed and overcoming these limitations by means of digital implementation has been proposed. The complete design procedure of the proposed technique has been presented with an illustrative example. The three-phase VSI feeding an inductive load has also been simulated by using MATLAB and the simulation results have been presented. The hardware results of hysteresis current controlled three-phase VSI feeding an inductive load have been presented. Also the performance analysis of the hysteresis current controller has been presented. Operation of this controller has also been explained with a help of phase plane trajectory of hysteresis controller.
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VISHNU MOHAN MISHRA
2012-03-01
Full Text Available The aim of this paper is to present a novel control scheme and designing of reactance parameter of PWM convereterand, find the optimized value of parameters for voltage PI controller for three phase ac/dc PWM converter. Using new trends Genetic algorithms- are discussed, as well.Paper describes the application of Genetic Algorithms for optimization of controller parameters of PWM converter. The behavior of the stability region is plotted with different sampling periods.Genetic Algorithms used for off-line searching Using the MATLAB, the simulation model of the dc- link PWM ac/dc converter is built up. According to the simulation results, it is known that, the presented control strategy is feasible and valid, and the converter can work well under dc motor load condition, and thus the total harmonics distortion (THD can be reduced quickly and effectively. The PWM rectifier operates as a rectifier to supply dc power to its load a dc motor and at the same time, to improve the power factor and to compensate harmonics drawn from non-linear loads connected on the ac line.
An Optimal PR Control Strategy with Load Current Observer for a Three-Phase Voltage Source Inverter
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Xiaobo Dou
2015-07-01
Full Text Available Inverter voltage control is an important task in the operation of a DC/AC microgrid system. To improve the inverter voltage control dynamics, traditional approaches attempt to measure and feedforward the load current, which, however, needs remote measurement with communications in a microgrid system with distributed loads. In this paper, a load current observer (LCO based control strategy, which does not need remote measurement, is proposed for sinusoidal signals tracking control of a three-phase inverter of the microgrid. With LCO, the load current is estimated precisely, acting as the feedforward of the dual-loop control, which can effectively enlarge the stability margin of the control system and improve the dynamic response to load disturbance. Furthermore, multiple PR regulators are applied in this strategy conducted in a stationary frame to suppress the transient fluctuations and the total harmonic distortion (THD of the output voltage and achieve faster transient performance compared with traditional dual-loop control in a rotating dq0 frame under instantaneous change of various types of load (i.e., balanced load, unbalanced load, and nonlinear load. The parameters of multiple PR regulators are analyzed and selected through the root locus method and the stability of the whole control system is evaluated and analyzed. Finally, the validity of the proposed approach is verified through simulations and a three-phase prototype test system with a TMS320F28335 DSP.
DEFF Research Database (Denmark)
Lar, Ionut Andrei; Radulescu, Mircea
2012-01-01
A comparison between two current control methods of grid side inverter, PI current control and Robust Forward control is made. PI control is implemented in d-q synchronous frame while Forward is implemented in abc stationary frames.The report contains both simulations and experimental test wich were made at a reduced scale ( 2.2 kW). The constant power test showed that both method have good results which can respect existing grid codes. The constant power test showed that both method have good results which can respect existing grid codes.
An Analytical Modelling of Three-Phase Four-Switch PWM Rectifier Under Unbalanced Supply Conditions.
Czech Academy of Sciences Publication Activity Database
Klíma, J.; Škramlík, Ji?í; Valouch, Viktor
2007-01-01
Ro?. 54, ?. 12 (2007), s. 1155-1159. ISSN 1549-7747 R&D Projects: GA AV ?R IAA200760703 Institutional research plan: CEZ:AV0Z20570509 Keywords : modelling * pulsewidth modulation (PWM) * reactive power Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.104, year: 2007
Analytical closed-form solution of three-phase four-switch PWM rectifier.
Czech Academy of Sciences Publication Activity Database
Škramlík, Ji?í; Valouch, Viktor; Klíma, J.; Pecha, I.
2010-01-01
Ro?. 55, ?. 3 (2010), s. 223-235. ISSN 0001-7043 R&D Projects: GA MPO FT-TA5/123 Institutional research plan: CEZ:AV0Z20570509 Keywords : four-switch PWM rectifier * space vector modulation * closed-form analytical solution Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Modeling and Implementation of Three-Phase Component Minimized PWM Converter.
Czech Academy of Sciences Publication Activity Database
Šimek, Petr; Škramlík, Ji?í; Valouch, Viktor; Klíma, J.
Brno : VUT FEKT Brno, 2008, s. 1-8. ISBN 978-80-7204-603-4. [Celostátní konference EPVE 2008. Brno (CZ), 11.11.2008-12.11.2008] R&D Projects: GA AV ?R IAA200760703 Institutional research plan: CEZ:AV0Z20570509 Keywords : four-switch PWM rectifier * space vector modulation * closed-form analytical solution Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Analytical Modeling and Implementation of Three-Phase Four-Switch Space-Vector PWM Converter.
Czech Academy of Sciences Publication Activity Database
Paclt, Zden?k; Šimek, Petr; Škramlík, Ji?í; Valouch, Viktor; Klíma, J.
Prague : Institute of Thermomechanics AS CR, v. v. i., 2008, s. 49-52. ISBN 978-80-87012-13-0. [Symposium Electric Machines and Drives, Power Electronics and Drive Control. Prague (CZ), 30.09.2008-02.10.2008] R&D Projects: GA AV ?R IAA200760703 Institutional research plan: CEZ:AV0Z20570509 Keywords : four-switch PWM rectifier * space vector modulation * closed-form analytical solution Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Comparative analysis of SPWM and SVPWM control for three phase inverter
Directory of Open Access Journals (Sweden)
K. Vinoth Kumar
2010-07-01
Full Text Available A voltage source inverter is commonly used to supply a three-phase induction motor with variable frequency and variable voltage for variable speed applications. A suitable pulse width modulation (PWM technique is employed to obtain the required output voltage in the line side of the inverter. The different methods for PWM generation can be broadly classified into triangle comparison based PWM (TCPWM and Space Vector based PWM (SVPWM. In TCPWM methods such as sine-triangle PWM, three phase reference modulating signals are compared against a common triangular carrier to generate the PWM signals for the three phases. In SVPWM methods, a revolving reference voltage vector is provided as voltage reference instead of three phase modulating waves. The magnitude and frequency of the fundamental component in the line side are controlled by the magnitude and frequency, respectively, of the reference vector. The highest possible peak phase fundamental is very less in sine triangle PWM when compared with space vector PWM. Space Vector Modulation (SVM technique has become the important PWM technique for three phase voltage source inverters for the control of AC Induction, Brushless DC, Switched Reluctance and Permanent Magnet Synchronous Motors. The study of space vector modulation technique reveals that space vector modulation technique utilizes DC bus voltage more efficiently and generates less harmonic distortion when compared with Sinusoidal PWM (SPWM technique. In this paper first a model for Space vector PWM is made and simulated using MATLAB/SIMULINK software and its performance is compared with Sinusoidal PWM. The simulation study reveals that Space vector PWM utilizes DC bus voltage more effectively and generates less THD when compared with sine PWM.
DEFF Research Database (Denmark)
Kouchaki, Alireza; Niroumand, Farideh Javidi
This paper presents an analytical method for designing the inductor of three-phase power factor correction converters (PFCs). The complex behavior of the inductor current complicates the inductor design procedure as well as the core loss and copper loss calculations. Therefore, this paper analyzes the inductor voltage/current for sinusoidal pulse width modulation technique. Accordingly, the maximum current ripple as a function of the dc link voltage is derived and the minimum required inductance value is calculated. To explain the copper and the core losses in the inductor, the single-phase equivalent circuit is used to provide the inductor current harmonic spectrum. Therefore, using the harmonic spectrum, the low and high frequency copper losses are calculated. The high frequency minor B-H loops in one switching cycle are also analyzed. Then, the loss map provided by the measurement setup is used to calculate the core loss in the PFC application. To investigate the impact of the dc link voltage level, two inductors for different dc voltage levels are designed and the results are compared.
International Nuclear Information System (INIS)
This paper is concerned with the design and implementation of current control of three-phase PWM rectifier based on predictive control strategy. The proposed predictive current control technique operates with constant switching frequency, using space-vector modulation (SVM). The main goal of the designed current control scheme is to maintain the dc-bus voltage at the required level and to achieve the unity power factor (UPF) operation of the converter. For this purpose, two predictive current control algorithms, in the sense of deadbeat control, are developed for direct controlling input current vector of the converter in the stationary ?-? and rotating d-q reference frame, respectively. For both predictive current control algorithms, at the beginning of each switching period, the required rectifier average voltage vector allowing the cancellation of both tracking errors of current vector components at the end of the switching period, is computed and applied during a predefined switching period by means of SVM. The main advantages of the proposed predictive current control are that no need to use hysteresis comparators or PI controllers in current control loops, and constant switching frequency. Finally, the developed predictive current control algorithms were tested both in simulations and experimentally, and illustrative results are presented here. Results have proven excellent performance in steady and transient states, and verify the validity of the proposed predictive current control which is compared to other control strategies.
Energy Technology Data Exchange (ETDEWEB)
Wi, Seog Oh [Chonnam National University, Kwangju (Korea); Jung, Young Gook [Daebul University, Youngam (Korea); Na, Seok Hwan [How Wireless and Navigation Co., Ltd (Korea)
2002-07-01
In this paper, a new Three-Phase Lead-Lag Random Pulse Position PWM(LL-RPWM) scheme is proposed and implemented for decreasing acoustic noise of motor drives. In the proposed RPWM(Random PWM), each of three phase pulses is located randomly in each switching interval. Based on the space vector modulation technique, the duty ratio of the pulses is calculated. Along with the randomization of the PWM pulses, we can obtain the effects of spread spectra of voltage, current as in the case of randomly changed switching frequency. To verify the validity of the proposed LL-RPWM, the simulation and experimental study was tried Along with the randomization of PWM pulses, the space vector modulation is also executed in the C167 micro-controller. The simulation and experimental results show that the voltage and current harmonics are spread to a wide band area and that the audible acoustic noise is reduced by the proposed RPWM method. (author). 14 refs., 21 figs., 1 tab.
International Nuclear Information System (INIS)
In this paper a new control strategy for voltage-source converters (VSC) is introduced. The proposed strategy consists of a nonlinear feedback controller based on feedback linearization plus a feedforward compensation of the estimated load current. In our proposal an energy function and the direct-axis current are considered as outputs, in order to avoid the internal dynamics. In this way, a full linearization is obtained via nonlinear transformation and feedback. An estimate of the load current is feedforwarded to improve the performance of the whole system and to diminish the capacitor size. This estimation allows to obtain a more rugged and cheaper implementation. The estimate is calculated by using a nonlinear reduced-order observer. The proposal is validated through different tests. These tests include performance in presence of switching frequency, measurement filters delays, parameters uncertainties and disturbances in the input voltage.
Czech Academy of Sciences Publication Activity Database
Chomát, Miroslav; Schreier, Lud?k
2005-01-01
Ro?. 152, ?. 3 (2005), s. 494-500. ISSN 1350-2352 R&D Projects: GA ?R(CZ) GA102/02/0554 Institutional research plan: CEZ:AV0Z20570509 Keywords : DC-link voltage * unbalanced three-phase voltage Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.587, year: 2005
DEFF Research Database (Denmark)
Padmanaban, Sanjeevikumar; Grandi, Gabriele
2015-01-01
This paper considered a six-phase (asymmetrical) induction motor, kept 30 phase displacement between two set of three-phase open-end stator windings configuration. The drive system consists of four classical three-phase voltage inverters (VSIs) and all four dc sources are deliberately kept isolated. Therefore, zero-sequence/homopolar current components cannot flow. The original and effective power sharing algorithm is proposed in this paper with three variables (degree of freedom) based on synchronous field oriented control (FOC). A standard three-level space vector pulse width modulation (SVPWM) by nearest three vectors (NTVs) approach is adopted to regulate each couple of VSIs. The proposed power sharing algorithm is verified by complete numerical simulation modeling (Matlab/ Simulink-PLECS software) of whole ac drive system by observing the dynamic behaviors in different designed condition. Set of results are provided in this paper, which confirms a good agreement with theoretical development.
Scientific Electronic Library Online (English)
M. E., Oliveira Filho; A. J., Sguarezi Filho; J. R., Gazoli; E., Ruppert Filho.
2010-10-01
Full Text Available Com o avanço da tecnologia dos dispositivos semicondutores de potęncia os inversores de frequęncia atuam de forma importante em toda indústria. O inversor de frequęncia convencional contém elementos armazenadores de energia no seu elo de corrente contínua. Estes elementos armazenadores de energia să [...] o capacitores eletrolíticos e possibilitam manter a tensăo do elo de corrente contínua constante. Entretanto, quanto maior sua capacitância maior é a distorçăo da corrente de entrada. Com a substituiçăo do banco de capacitores eletrolíticos por um capacitor de filme, diminui-se a distorçăo nas correntes de entrada, porém distorçőes indesejadas aparecem na tensăo do elo de corrente contínua e também nas correntes de saída. Estas distorçőes săo compostas por componentes harmônicas de baixas frequęncias. O conversor em matriz trifásico-trifásico por sua vez, possibilita a transferęncia direta de energia da entrada (rede) diretamente para a saída (carga) sem a necessidade de elementos armazenadores de energia como acontece no inversor de frequęncia. Entretando o desbalanceamento das tensőes da entrada afetam diretamente a forma de onda das tensőes da saída. Dessa maneira, este trabalho propőe um método de controle de corrente do conversor em matriz e do inversor de frequęncia sem banco de capacitores do elo de corrente contínua com objetivo de compensar o desbalanceamento das tensőes de saída do conversor em matriz e compensar também as componentes harmônicas de baixa frequęncia que aparecem nas correntes de saída do inversor de frequęncia. O método proposto utiliza um controlador do tipo PI e modulaçăo por vetores espaciais para que a frequęncia de acionamento das chaves dos conversores seja constante. Abstract in english Voltage source three-phase inverter plays an important role in modern industry. The conventional voltage source inverter has a large electrolytic capacitor as energy store element in order to keep the DC-link voltage constant. However, a large electrolytic capacitor increases the input current disto [...] rtion. Replacing the large electrolytic capacitor by a small film capacitor, the input current quality is improved but the DC-link voltage and the output currents are distorted by low order harmonic components. The three phase to three phase matrix converter performs electric energy direct transfer from the input to the output with sinusoidal input current although the distortion and the unbalance of the input voltages affects directly the output of the matrix converter. This paper proposes a load current control method to the matrix converter and also to the voltage source inverter in absence of the dc-link capacitor in order to compensate the distortion caused by low order harmonics components in the output currents. The proposed load current control scheme employs just one PI controller and since that the space vector modulation is used in this control, the switching frequency of the converter is kept constant. Theorical foundation, simulations results and experimental results are presented.
Optimum space vector PWM algorithm for three-level inverter
Directory of Open Access Journals (Sweden)
B. Urmila
2011-09-01
Full Text Available A Three - Level Voltage Source Inverter is used increasingly to supply a variable frequency and variable voltage for variable speed applications. A suitable pulse width modulation (PWM technique is employed to obtain the required output voltage at the line side of the inverter. This paper studies popular multi-level topology, Diode Clamped or Neutral Point Clamped for three-level. Two methods of Sine-triangle (SPWM and two methods of Space Vector Pulse Width Modulation (SVPWM are employed to generate the modulation wave. These modulation waves are compared against a triangular carrier to generate the PWM signals for the three phases. In SVPWM methods, a revolving reference voltage vector is provided as voltage reference instead of three phase modulating waves used in SPWM. The magnitude and frequency of the fundamental component in the line side are controlled by the magnitude and frequency, respectively, of the reference vector. Space Vector Modulation Technique has become the important PWM technique for three phase Voltage Source Inverters because of its increased dc bus utilization and reduced harmonic distortion compared to SPWM. The four PWM methods are simulated in MATLAB/SIMULINK software and are compared for THD and Capacitor Balance. Programs are carried out using Embedded Editor functions and matlab editor functions. The simulation study reveals that Space vector PWM utilizes dc bus voltage more effectively, generates less THD and improved capacitor balance when compared to sine PWM.
Three-phase Resonant DC-link Converter
Munk-Nielsen, Stig
1997-01-01
The purpose of the project is to develop a three-phase resonant converter suitable for standard speed drives. The motivation for working with resonant converters is found in the problem of the standard converter type used today. In standard converter type Pulse Width Modulated-Voltage Source Inverter, PWM-VSI, the switches are subject to high current and voltage stress during switching, which causes losses. The fast switching of modern switches reduces switching losses. Unfortunately this pro...
Czech Academy of Sciences Publication Activity Database
Klíma, J.; Škramlík, Ji?í; Valouch, Viktor
Prague : Czech Technical University, 2007, s. 80-86. ISBN 978-80-01-03807-9. [International Symposium on Electric Machinery /15./. Prague (CZ), 05.09.2007-06.09.2007] Institutional research plan: CEZ:AV0Z20570509 Keywords : PWM rectifier * space-vector modulation * unbalance supply Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Czech Academy of Sciences Publication Activity Database
Klíma, J.; Škramlík, Ji?í; Valouch, Viktor
Sichuan : Sichuan University, 2008, s. 1-4. ISBN 978-1-4244-1706-3. [IEEE International Conference on Industrial Technology (ICIT 2008). Chengdu (CN), 21.04.2008-24.04.2008] R&D Projects: GA AV ?R IAA200760703 Institutional research plan: CEZ:AV0Z20570509 Keywords : four-switch PWM rectifier * space vector modulation * unbalance supply Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Energy Technology Data Exchange (ETDEWEB)
Bouafia, Abdelouahab; Krim, Fateh [Laboratoire d' Electronique de Puissance et Commande Industrielle (LEPCI), Universite de Setif, Departement d' electronique, Route de Bejaia, Setif (Algeria); Gaubert, Jean-Paul [Laboratoire d' Automatique et d' Informatique Industrielle (LAII), ESIP, Universite de Poitiers (France)
2009-01-15
This paper proposes direct power control (DPC) for three-phase PWM rectifiers using a new switching table, without line voltage sensors. The instantaneous active and reactive powers, directly controlled by selecting the optimum state of the converter, are used as the PWM control variables instead of the phase line currents being used. The main goal of the control system is to maintain the dc-bus voltage at the required level, while input currents drawn from the power supply should be sinusoidal and in phase with respective phase voltages to satisfy the unity power factor (UPF) operation. Conventional PI and a designed fuzzy logic-based controller, in the dc-bus voltage control loop, have been used to provide active power command. A dSPACE based experimental system was developed to verify the validity of the proposed DPC. The steady-state, and dynamic results illustrating the operation and performance of the proposed control scheme are presented. As a result, it was confirmed that the novel DPC is much better than the classical one. Line currents very close to sinusoidal waveforms (THD < 2%) and good regulation of dc-bus voltage are achieved using PI or fuzzy controller. Moreover, fuzzy logic controller gives excellent performance in transient state, a good rejection of impact load disturbance, and a good robustness. (author)
DEFF Research Database (Denmark)
Blaabjerg, Frede; Aquila, A. Dell?
2004-01-01
A systematic approach to study dc/ac and ac/dc converters without the use of synchronous transformation is proposed. The use of a frequency-shift technique allows a straightforward analysis of single-phase and three-phase systems. The study of dc/ac and of ac/dc converters is reported to the study of dc/dc converters via a 50 Hz frequency-shift. The input admittance is calculated and measured for two study examples (a three-phase active rectifier and a single-phase photovoltaic inverter). These examples show that the purpose of a well designed controller for grid-connected converters is to minimize the input admittance in order to make the grid converter more robust to grid disturbance.
Directory of Open Access Journals (Sweden)
Mechouma Rabiaa
2014-01-01
Full Text Available In recent years, power demand of industrial applications has increased significantly reaching some megawatts. The use of multilevel converters for applications of medium and high powers is proposed as a solution to drawback semiconductor technology. A multilevel converter not only achieves high power ratings, but also enables the use of renewable energy sources. Renewable energy sources such as photovoltaic can be easily interfaced to a multilevel converter system for a high power application. This paper presents the simulation study in Matlab/Simulink of a grid connected photovoltaic three phase Neutral Point Clamped (NPC inverter with DC/DC boost converter for constant and variable solar radiation.
Scientific Electronic Library Online (English)
Rudolf Ribeiro, Riehl; Ernesto, Ruppert.
2012-04-01
Full Text Available A proposta deste trabalho é apresentar uma nova metodologia para determinaçăo experimental das capacitancias parasitas do motor de induçăo trifásico de rotor em gaiola. As capacitancias parasitas fazem parte do circuito equivalente do motor para estudos de interferęncia eletromagnética causada no mo [...] tor de induçăo em modo comum quando ele for acionado por inversor controlado por modulaçăo por largura de pulsos (MLP). Os procedimentos propostos para o desenvolvimento deste novo método consistem em: a) determinaçăo dos parâmetros do circuito equivalente do motor de induçăo trifásico, em regime permanente, através de ensaio em laboratório; b) estabelecer configuraçőes de ligaçőes entre o inversor MLP e o motor para mediçőes das grandezas de interesse que săo as seguintes: tensőes de modo comum e de eixo, correntes de fuga e de eixo, através de circuito de mediçăo desenvolvido para este fim; c) calcular os valores das capacitancias parasitas entre estator e carcaça do motor; estator e rotor; rotor e carcaça e de rolamento utilizando a expressăo matemática da definiçăo de capacitancia; d) utilizar o software Pspice para simular o sistema motor de induçăo trifásico, alimentado por inversor MLP, com os circuitos equivalentes em baixas e altas frequęncias; e) obter as formas de onda características do fenômeno de modo comum. Abstract in english Three-phase induction motors present stray capacitances. The aim of this paper is to present a new methodology to experimentally determine these capacitances and also evaluates the effects of electromagnetic interference on the motors in common mode. The proposed procedures to the development of thi [...] s new methodology consists in: a) identification of the motor equivalent electrical circuit parameters through characteristic tests performed in the laboratory; b) to set up configurations between PWM inverter and the motor for voltage and current measurements: common mode and shaft voltages, leakage and shaft (bearing) currents by using a dedicated measuring circuit; c) to calculate the parasitic capacitance values between stator and frame, stator and rotor, rotor and frame and bearings of the motor using the capacitance characteristic equation; d) use the dedicated software Pspice to simulate the system composed by the three-phase induction motor fed by PWM inverter with the equivalent electrical circuit parameters; e) to determine the characteristic waveforms involved in the common mode phenomenon.
Space Vector Pulse Width Modulation Scheme for a Seven-Phase Voltage Source Inverter
Directory of Open Access Journals (Sweden)
Mohd. Arif Khan
2011-09-01
Full Text Available This paper analyses a simple space vector PWM (SVPWM scheme for a seven-phase voltage source inverter. At first the conventional method of producing sinusoidal output voltage by utilizing six active and a zero space vectors are used to synthesis the input reference and then new PWM scheme called time equivalent space vector PWM is presented. A comparison of the proposed scheme with the conventional scheme is presented based on various performance indices. Extensive Simulation results are provided to validate the findings
Three-phase Resonant DC-link Converter
DEFF Research Database (Denmark)
Munk-Nielsen, Stig
1997-01-01
The purpose of the project is to develop a three-phase resonant converter suitable for standard speed drives. The motivation for working with resonant converters is found in the problem of the standard converter type used today. In standard converter type Pulse Width Modulated-Voltage Source Inverter, PWM-VSI, the switches are subject to high current and voltage stress during switching, which causes losses. The fast switching of modern switches reduces switching losses. Unfortunately this procedure increased dv/dt and the size of the input/output filters of the PWM-SVI must be increased. The high speed of the switches cannot be fully utilizied. By using a parallel resonant converter the switching happens at low or zero voltage which reduses switch losses. The dv/dt is controlled by the resonant circuit, and it is therefore reduced significantly. The perspective using a resonant converter is high switching frequency combined with a high converter efficiency and low dv/dt. In the first report several resonant converters are investigated to find a resonant converter that can complete with the standard PWM-VSI converter. Four converters were selected for the theoretical analysis, and the converters are simulated. An evaluation of the resonant converters is made, and one converter is selected for the realization. In the second report the realization of the selected resonant converter is described. This includes analysis, design and test of the converter. A new control principle, using no additional power electric components is eliminating the high voltage peaks associated with the resonant circuit. The resonant link voltage peaks are limited below 2.1 times the DC link voltages. A new principle eliminating former resonant converter stability problems are proposed, implemented and tested. A resonant converter efficiency of 97 [%] was measured. The low dv/dt of the converter makes it possible to drive long cables without filtering. A successful test with a 300 [m] long cable and an induction machine load wascarried out. It is concluded that a stable, high efficiency and high switching frequency three phase parallel resonant converter is realized.
Comparative Study of Multicarrier PWM Techniques for a Modular Multilevel Inverter
Rajan, M S; R.Seyezhai
2014-01-01
This paper presents the simulation of three phase five-level modular multilevel cascade inverter based on double-star chopper-cell (DSCC). The multicarrier PWM techniques such as Phase disposition PWM (PDPWM), Phase opposition disposition PWM (PODPWM), Alternate phase opposition disposition PWM (APODPWM), and Phase shift PWM (PSPWM) is employed and a comparative study is done based on the spectral quality of the load voltage and load current waveforms. Simulation has been carried out for vari...
Design and Analysis of Adaptive Neural Controller for Voltage Source Converter for STATCOM
Ganesh, Aman; Singh, G. K.; Dahiya, Ratna
2011-01-01
Usually a STATCOM is installed to support power system networks that have a poor power factor and often poor voltage regulation. It is based on a power electronics voltagesource converter. Various PWM techniques make selective harmonic elimination possible, which effectively control the harmonic content of voltage source converters. The distribution systems have to supply unbalanced nonlinear loads transferring oscillations to the DC-side of the converter in a realistic operating condition. T...
Analytical Method to Calculate the DC Link Current Stress in Voltage Source Converters
DEFF Research Database (Denmark)
Gohil, Ghanshyamsinh Vijaysinh; Bede, Lorand
2014-01-01
The dc-link capacitor is one of the critical components, which influences the lifetime of the whole voltage source converter unit. For reliable design, the operating temperature of the dc-link capacitor should be known, which is primarily determined by the ambient temperature and the rms value of the current flowing through the dc-link capacitor. A simple analytical method to calculate the rms value of the dc-link capacitor current is presented in this paper. The effect of the line current ripple on the rms value of the dc-link capacitor current is considered. This yields accurate results, especially for the applications with high line current ripple. The effect of the pulsewidth modulation (PWM) scheme on the rms value of the dc-link current is also studied and the analysis for continuous PWM and discontinuous PWM (DPWM) schemes is presented. The proposed analytical method is also verified experimentally.
Modeling & Simulation of Fuel cell (Choi Model) based 3-Phase Voltage Source Inverter
Gaurav Sachdeva
2011-01-01
In the present work, performance of three phase voltage source inverter, while feeding different power factor loads, has been investigated. Fuel cells models namely Choi model are used in input side as a DC source while dynamic load have been used at the output side. Dynamic load used is induction motor (IM). Performance of IM has been investigated under various loading conditions. ANN based control strategy has been proposed to find the conduction angle of a Three Phase VSI and verified for ...
Directory of Open Access Journals (Sweden)
S. Elangovan
2014-07-01
Full Text Available The main aim of this study is to control a multivariable coupled system by choosing sliding mode switching function. A Sliding mode control approach is developed to control a three phase three wire voltage source inverter operating as a shunt active power filter. Hence, no need to divide the system model developed in the synchronous ‘dq’ reference frame into two separate loops. Furthermore, the proposed control strategy allows a better stability and robustness over a wide range of operation. When sine PWM is used for generation of pulses for the switches, a variable switching nature is exhibited. The pulses for the active filter are fed by a Space Vector Modulation in order to have a constant switching of converter switches. But, the conventional space vector modulation, if implemented practically, needs a complicated algorithm which uses the trigonometric functions such as arctan, Sine and Cosine functions which in turn needs look up tables to store the pre-calculated trigonometric values. In this study, a very simplified algorithm is proposed for generating Space vector modulated pulse for all six switches without the use of look up tables and only by sensing the voltages and currents of the voltage source inverter acting as shunt active filter. The simulation using PSIM and MATLAB software verifies the results very well.
Soft Commutated Three-Phase Dc-Dc Converter
Silpa.P.T; Rajeenamol P.T
2014-01-01
High efficient DC-DC Converters find its application in electric power generation, transmission, distribution and Uninterruptable power supplies (UPS). Three phase converter system as compared with single phase converter system increases power density with reduced switching stresses, efficient usage of the transformer magnetic core and smaller filter design as the frequency of the system is higher. Inorder to make use of the above mentioned advantages a ZVS-PWM three- phase current-fed push-p...
Compensation of Unbalanced Three-Phase Voltage Supply in Voltage Source Inverter.
Czech Academy of Sciences Publication Activity Database
Chomát, Miroslav; Schreier, Lud?k
2003-01-01
Ro?. 48, ?. 2 (2003), s. 113-128. ISSN 0001-7043 R&D Projects: GA ?R GA102/02/0554 Institutional research plan: CEZ:AV0Z2057903 Keywords : unbalanced voltage supply * power factor correction * DC-link current pulsations Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Czech Academy of Sciences Publication Activity Database
Chomát, Miroslav; Schreier, Lud?k
Rio de Janeiro : IEEE Service Center, 2003, s. -. ISBN 0-7803-7912-8. [IEEE International Symposium on Industrial Electronics - ISIE 2003. Rio de Janeiro (BR), 09.06.2003-11.06.2003] R&D Projects: GA ?R GA102/02/0554 Institutional research plan: CEZ:AV0Z2057903 Keywords : unbalanced voltage supply * power factor correction * DC-link current pulsations Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
DEFF Research Database (Denmark)
Kwon, Jun Bum; Wang, Xiongfei
2015-01-01
As the increasing of power electronics based systems, not only the component-based analysis but also a systematic interaction analysis with each other systems are being important. Especially studies about the stability and the harmonics interaction are critical in order to establish the required performance in a power network. However, the traditional small-signal modeling approaches are not enough to represent the complexity of the interaction due to the time varying components of such systems. This paper compares the small-signal modeling methods for harmonic analysis of AC - DC converters and discusses their advantages and limitations. The Harmonic State Space (HSS) model based on the Linear Time-Periodically varying (LTP) system and the traditional small signal model based on the Linear Time-Invariant (LTI) system are evaluated. The results show that the HSS model presents superior performance for the AC-DC converters with a low ratio of switching to the fundamental frequency, and it provides an effectiveway to reveal the harmonic interaction and stability analysis for the future power electronics based power systems.
Comparative Study of Multicarrier PWM Techniques for a Modular Multilevel Inverter
Directory of Open Access Journals (Sweden)
M.S.Rajan
2014-01-01
Full Text Available This paper presents the simulation of three phase five-level modular multilevel cascade inverter based on double-star chopper-cell (DSCC. The multicarrier PWM techniques such as Phase disposition PWM (PDPWM, Phase opposition disposition PWM (PODPWM, Alternate phase opposition disposition PWM (APODPWM, and Phase shift PWM (PSPWM is employed and a comparative study is done based on the spectral quality of the load voltage and load current waveforms. Simulation has been carried out for various modulation indices using MATLAB/Simulink and the results are verified.
Improved Indirect Rotor Flux Oriented Control of PWM inverter fed Induction Motor Drives
Gerald Christopher Raj, I.; P. Renuga, Dr.; Arul Prasanna, M.
2010-01-01
In today's high-power electrical drives using vector controlled induction machines, voltage source inverters (VSI) based on PWM technology and current source inverters (CSI) based on based on PWM technology are the most important alternatives for motor supply (cyclo-converters being confined to very low speed applications). In this paper an Induction motor modeled in the rotor flux reference frame, the rotor flux orientation is obtained, a high performance current fed Indirect Rotor Flux Orie...
Single Phase Voltage Source Inverter Photovoltaic Application
Directory of Open Access Journals (Sweden)
J. Bauer
2010-01-01
Full Text Available Photovoltaic applications have been developing and spreading rapidly in recent times. This paper describes the control strategy of the Voltage Source Inverter that is the important tail end of many photovoltaic applications.In order to supply the grid with a sinusoidal line current without harmonic distortion, the inverter is connected to the supply network via a L-C-L filter. The output current is controlled by the hysteresis controller. To improve the behaviors of the L-C-L filter, active damping of the filter is being used. This paper discusses controller design and simulation results.
Single Phase Voltage Source Inverter Photovoltaic Application
Bauer, J.
2010-01-01
Photovoltaic applications have been developing and spreading rapidly in recent times. This paper describes the control strategy of the Voltage Source Inverter that is the important tail end of many photovoltaic applications.In order to supply the grid with a sinusoidal line current without harmonic distortion, the inverter is connected to the supply network via a L-C-L filter. The output current is controlled by the hysteresis controller. To improve the behaviors of the L-C-L filter, active d...
Directory of Open Access Journals (Sweden)
P. Avirajamanjula
2015-03-01
Full Text Available A direct Selective current harmonic elimination pulse width modulation technique is proposed for induction motor drive fed from voltage source inverter. The developed adaptive filtering algorithm for the selective current harmonic elimination in a three phase Voltage Source Inverter is a direct method to improve the line current quality of the Voltage Source Inverter base drive at any load condition. The self-adaptive algorithm employed has the capability of managing the time varying nature of load (current. The proposed Normalized Least Mean Squares algorithm based scheme eliminates the selected dominant harmonics in load current using only the knowledge of the frequencies to be eliminated. The algorithm is simulated using Matlab/Simulink tool for a three-phase Voltage Source Inverter to eliminate the fifth and seventh harmonics. The system performance is analyzed based on the simulation results considering total harmonic distortion, magnitude of eliminated harmonics and harmonic spectrum. The corroboration is done in the designed Voltage Source Inverter feeding induction motor using digital signal processor-TMS320L2812.The developed algorithm is transferred to digital signal processor using VisSimTM software.
Directory of Open Access Journals (Sweden)
N. Belhaouchet
2008-03-01
Full Text Available Hysteresis current control is one of the simplest techniques used to control the magnitude and phase angle of motor current for motor drives systems. However, this technique presents several disadvantages such as operation at variable switching frequency which can reveal problems of filtering, interference between the phases in the case of the three-phase systems with insulated neutral connection or delta connection, and irregularity of the modulation pulses which especially causes an acoustic noise on the level of the machine for the high power drive. In this paper, a new technique is proposed for a variable-hysteresis-band controller based on dead beat control applied to three phase voltage source PWM inverters feeding AC motors. Its main aim is firstly ensure a constant switching frequency and secondly the synchronization of modulation pulses using the phase-locked-loop with loop gain compensation in order to ensure a better stability. The behavior of the proposed technique is verified by simulation.
A Review of Passive Filters for Grid-Connected Voltage Source Converters
DEFF Research Database (Denmark)
Beres, Remus Narcis; Wang, Xiongfei
2014-01-01
LCL filter is the common interface between the Pulse Width Modulated Voltage Source Converter (PWM VSC) and the utility grid due to high harmonic attenuation capability and reduced size of the passive elements. The present paper investigates the most promising passive damping methods for the LCL topology but also propose an overview of high order filters capable to offer even more attenuation than the LCL filter at a reduced size. This is the case of more recently introduced LCL topology with tuned traps. However, it is shown that by decreasing the size of the passive elements the robustness of the filter also is decreased. Thus, a comparison of the filter features including the robustness towards grid impedance variation, harmonic attenuation capability and losses in the damping circuit became interesting from a practical implementation point of view. The design of the proposed filters is validated by simulation and experimental results and covers two scenarios: high and low/medium power applications.
Scientific Electronic Library Online (English)
Alberto, Berzov; Julio, Viola; José, Restrepo.
2012-09-01
Full Text Available Este trabajo presenta dos técnicas de control de corriente para convertidores trifásicos de voltaje trabajando como rectificadores controlados, operando con factor de potencia unitario. El primer algoritmo está basado en la escogencia del mejor vector natural, entre los 7 vectores espaciales natural [...] es del convertidor de dos niveles de voltaje trifásico, mediante una función de costo. El segundo está basado en el cómputo y síntesis del vector espacial óptimo de convertidores trifásicos tal que se obtiene el vector que proporciona un mínimo absoluto de la función de costo. El primer algoritmo es un método sencillo que controla muy bien el factor de potencia y presenta una considerable compensación del contenido armónico. El segundo algoritmo provee una nueva fórmula cerrada para calcular el vector de voltaje óptimo aplicado al convertidor. Para este segundo método se necesita generar la seńal de control con un modulador de ancho de pulso para así controlar directamente la corriente de línea permitiendo seguir la referencia de corriente. Las simulaciones y resultados experimentales muestran las ventajas del algoritmo propuesto. Abstract in english This work presents two current loop techniques, for three phase voltage source converters (VSC) used as controlled rectifiers (CR) operating at unity power factor. The first one is based on choosing the best natural vector, among the natural space vectors produced by two level voltage source inverte [...] rs, with the use of a cost function. The second one is based on computing and synthesizing a space vector such that an absolute minimum in the cost function is obtained. The first algorithm is a simple method that presents power factor correction and good total harmonic distortion compensation. The second algorithm provides a novel and closed form formula to calculate the optimum voltage vector applied by the converter. In this method, pulse width modulation (PWM) is required to modulate the voltage vector that controls directly the line current, to follow the current reference. The simulations and experimental results show the advantages of the proposed control algorithm.
V.Arun#1 , B.Shanthi
2013-01-01
This paper presents multicarrier PWM strategies for three phase diode clamped seven level Z-source inverter. Multilevel inverters posses the advantage of reduced harmonics,high power capability and high voltage level. Impedance network in the diode clamped multilevel inverter circuit will perform boost operation. This paper focuses on multicarriersinusoidal pulse width modulation (MCSPWM) strategy for the three phase seven level Z-source diode clamped inverter. Performance parameters of three...
Directory of Open Access Journals (Sweden)
Sérgio Augusto Oliveira da Silva
2005-06-01
Full Text Available This paper presents a three-phase line-interactive uninterruptible power supply (UPS system with active series-parallel power-line conditioning capabilities. Synchronous reference frame (SRF-based controller is used for harmonic and reactive power compensation generated from any configuration of non-linear loads. Under normal line conditions the UPS system works with universal filtering capabilities, such as compensating the input currents and output voltages. Two three-phase pulsewidth modulation (PWM converters, called series and parallel active filters, are used to perform the series and parallel active power-line compensation. The series active filter works as sinusoidal current source in phase with the input voltage, drawing from utility sinusoidal and balanced input currents with low total harmonic distortion (THD. The parallel active filter works as sinusoidal voltage source in phase with the input voltage, providing regulated and sinusoidal output voltages with low THD. The performance of the UPS system is evaluated in three-phase, four-wire systems. Experimental results are presented to confirm the theoretical studies.Este artigo apresenta um sistema de energia ininterrupta (SEI line-interactive trifásico com capacidade de condicionamento ativo de potęncia série e paralelo. Um controlador baseado no sistema de eixo de referęncia síncrona (SRF é usado na compensaçăo de potęncia reativa e harmônica geradas por quaisquer configuraçőes de cargas năo lineares. Sob condiçőes normais da rede elétrica o SEI trabalha na compensaçăo das correntes de entrada e das tensőes de saída. Dois conversores controlados em tensăo e modulados por largura de pulso (PWM, chamados de filtros ativos série e paralelo, săo usados para realizar o condicionamento ativo de potęncia série e paralelo. O filtro ativo série trabalha como uma fonte de corrente senoidal em fase com a tensăo de entrada, drenando da rede correntes senoidais, balanceadas com baixas taxas de distorçăo harmônica (TDH. O filtro ativo paralelo trabalha como uma fonte de tensăo senoidal em fase com a tensăo de entrada, fornecendo para a carga tensőes reguladas, senoidais e com baixas taxas de distorçăo harmônica. O desempenho do SEI é avaliado para sistemas trifásicos com quatro fios. Resultados experimentais săo apresentados para confirmar os estudos teóricos.
Scientific Electronic Library Online (English)
Sérgio Augusto Oliveira da, Silva; Pedro F., Donoso-Garcia; Porfírio C., Cortizo; Paulo F., Seixas.
2005-06-01
Full Text Available Este artigo apresenta um sistema de energia ininterrupta (SEI) line-interactive trifásico com capacidade de condicionamento ativo de potęncia série e paralelo. Um controlador baseado no sistema de eixo de referęncia síncrona (SRF) é usado na compensaçăo de potęncia reativa e harmônica geradas por qu [...] aisquer configuraçőes de cargas năo lineares. Sob condiçőes normais da rede elétrica o SEI trabalha na compensaçăo das correntes de entrada e das tensőes de saída. Dois conversores controlados em tensăo e modulados por largura de pulso (PWM), chamados de filtros ativos série e paralelo, săo usados para realizar o condicionamento ativo de potęncia série e paralelo. O filtro ativo série trabalha como uma fonte de corrente senoidal em fase com a tensăo de entrada, drenando da rede correntes senoidais, balanceadas com baixas taxas de distorçăo harmônica (TDH). O filtro ativo paralelo trabalha como uma fonte de tensăo senoidal em fase com a tensăo de entrada, fornecendo para a carga tensőes reguladas, senoidais e com baixas taxas de distorçăo harmônica. O desempenho do SEI é avaliado para sistemas trifásicos com quatro fios. Resultados experimentais săo apresentados para confirmar os estudos teóricos. Abstract in english This paper presents a three-phase line-interactive uninterruptible power supply (UPS) system with active series-parallel power-line conditioning capabilities. Synchronous reference frame (SRF)-based controller is used for harmonic and reactive power compensation generated from any configuration of n [...] on-linear loads. Under normal line conditions the UPS system works with universal filtering capabilities, such as compensating the input currents and output voltages. Two three-phase pulsewidth modulation (PWM) converters, called series and parallel active filters, are used to perform the series and parallel active power-line compensation. The series active filter works as sinusoidal current source in phase with the input voltage, drawing from utility sinusoidal and balanced input currents with low total harmonic distortion (THD). The parallel active filter works as sinusoidal voltage source in phase with the input voltage, providing regulated and sinusoidal output voltages with low THD. The performance of the UPS system is evaluated in three-phase, four-wire systems. Experimental results are presented to confirm the theoretical studies.
Valantina Stephen; L. Padma Suresh; Muthukumar, P
2012-01-01
This study proposes different configurations of PWM techniques for harmonic reduction and improvement of fundamental peak voltage. For providing adjustable frequency power to industrial applications, three-phase inverter is preferred. The general aim of this study is to reduce the third order harmonics and improve the Harmonic Spread Factor by different PWM techniques using matlab modelsim cosimulation. The gating signals to the inverter are produced by means of SPWM, RFPWM, Third Harmonic In...
Implementation of a Hybrid High Power Factor Three-Phase Unidirectional Rectifier
Directory of Open Access Journals (Sweden)
Ankusha Biradar,
2013-03-01
Full Text Available This paper presents a new hybrid three phase rectifier composed by the parallel association of a single switch three phase boost rectifier with a pwm three phase unidirectional rectifier. According to this proposal each rectifier processes about half of the output rated power. The diode rectifier operates at a low frequency and has a higher output power rating Therefore ,the pwm unidirectional rectifier is designed to operate with a small power rating and a high switching frequency. In the proposed scheme, dsPIC30F2010 controller is used to produce signals. A resistive load(Two incandescent lamps with different watts are used as load for testing the developed hardware. Textronics TDS2024B storage oscilloscope is used to store the gate pulses and waveforms. The perfectly sinusoidal input currents with improved power factor can be obtained by this hybrid rectifier.
Design of New Single-phase Multilevel Voltage Source Inverter
Directory of Open Access Journals (Sweden)
Rasoul Shalchi Alishah
2014-07-01
Full Text Available Multilevel inverters with more number of levels can produce high quality voltage waveforms. In this paper, a new single-phase structure for multilevel voltage source inverter is proposed which can generate a large number of levels with reduced number of IGBTs, gate driver circuits and diodes. Three algorithms for determination of dc voltage sources’ magnitudes are presented which provide odd and even levels at the output voltage waveform. A comparison is presented between proposed multilevel inverter and conventional cascade topology. The proposed topology is analyzed by the experimental and simulation results.
Power Loss Calculation and Thermal Modelling for a Three Phase Inverter Drive System
Directory of Open Access Journals (Sweden)
Z. Zhou
2005-12-01
Full Text Available Power losses calculation and thermal modelling for a three-phase inverter power system is presented in this paper. Aiming a long real time thermal simulation, an accurate average power losses calculation based on PWM reconstruction technique is proposed. For carrying out the thermal simulation, a compact thermal model for a three-phase inverter power module is built. The thermal interference of adjacent heat sources is analysed using 3D thermal simulation. The proposed model can provide accurate power losses with a large simulation time-step and suitable for a long real time thermal simulation for a three phase inverter drive system for hybrid vehicle applications.
Energy Technology Data Exchange (ETDEWEB)
Gheraia, H.; Berkouk, E.M. [ENP, Alger (Algeria). Lab. de Commande des Processus; Manesse, G. [CNAM-Paris (France). Lab. d' Electricite Industrielle
2001-08-01
In this paper, we study a new kind of continuous-alternating converters: a seven-level neutral point clamping (NPC) voltage source inverter (VSI). We propose this inverter for applications in high voltage and high power fields. In the first part, we develop the knowledge and the control models of this inverter using the connections functions of the semi-conductors. After that, we present two pulse width modulation (PWM) algorithms to control this converter using its control model. We propose these algorithms for digital implementation. This multilevel inverter is associated to the induction machine. The performances obtained are full of promise to use it in the high voltage and high power fields of electrical traction. (orig.)
Gheraia, H.; Berkouk, E. M.; Manesse, G.
2001-08-01
In this paper, we study a new kind of continuous-alternating converters: a seven-level neutral point clamping (NPC) voltage source inverter (VSI). We propose this inverter for applications in high voltage and high power fields. In the first part, we develop the knowledge and the control models of this inverter using the connections functions of the semi-conductors. After that, we present two pulse width modulation (PWM) algorithms to control this converter using its control model. We propose these algorithms for digital implementation. This multilevel inverter is associated to the induction machine. The performances obtained are full of promise to use it in the high voltage and high power fields of electrical traction.
Dynamics of voltage source converter in a grid connected solar photovoltaic system
DEFF Research Database (Denmark)
Haribabu, Divyanagalakshmi; Vangari, Adithya
2015-01-01
This paper emphasises the modelling and control of a voltage source converter (VSC) for three phase grid connected PV system. The transfer functions for inner current control and outer DC link voltage control for VSC are derived. The controllers for VSC are designed based on PI and K factor control methods and the performance of VSC using both the methods are presented with the simulations performed using PSCAD/EMTDC. The design of LC filter to meet the specified THD requirement for grid connected VSC is presented and the corresponding harmonic analysis is performed for different solar radiation conditions. The effectiveness of the proposed controller is illustrated by evaluating the response of PV system for power system voltage sag and swell conditions as well as grid faults.
Soft Commutated Three-Phase Dc-Dc Converter
Directory of Open Access Journals (Sweden)
Silpa.P.T
2014-08-01
Full Text Available High efficient DC-DC Converters find its application in electric power generation, transmission, distribution and Uninterruptable power supplies (UPS. Three phase converter system as compared with single phase converter system increases power density with reduced switching stresses, efficient usage of the transformer magnetic core and smaller filter design as the frequency of the system is higher. Inorder to make use of the above mentioned advantages a ZVS-PWM three- phase current-fed push-pull dc-dc converter with active clamping was developed. This converter topology allows the reuse of the energy from the leakage inductances and reduces the electromagnetic interferences (EMI. The topology was designed and simulated using MATLAB/SIMULINK. The input supply voltage used for the converter is 120V DC.
Parallel Interleaved VSCs : Influence of the PWM Scheme on the Design of the Coupled Inductor
DEFF Research Database (Denmark)
Gohil, Ghanshyamsinh Vijaysinh; Bede, Lorand
2014-01-01
The line current ripple and the size of the dc-link capacitor can be reduced by interleaving the carriers of the parallel connected Voltage Source Converters (VSCs). However, the interleaving of the carriers gives rise to the circulating current between the VSCs, and it should be suppressed. To limit the circulating current, magnetic coupling between the interleaved legs of the corresponding phase is provided by means of a Coupled Inductor (CI). The design of the CI is strongly influenced by the Pulsewidth Modulation (PWM) scheme used. The analytical model to evaluate the flux-linkage in the CI is presented in this paper. The maximum flux density and the core losses, being the most important parameters for the CI design, are evaluated for continuous PWM and discontinuous pulsewidth modulation (DPWM) schemes. The effect of these PWM schemes on the design of the CI is discussed. The simulation and the experimental results are finally presented to validate the analysis.
Optimal Operation of Voltage Source Inverter under Unbalanced Voltage Supply.
Czech Academy of Sciences Publication Activity Database
Chomát, Miroslav; Schreier, Lud?k; Bendl, Ji?í
Hannover : Leibniz University of Hannover, 2006, s. 35-40. [Symposium 2006 /8./. Hannover (DE), 27.09.2006-28.09.2006] R&D Projects: GA ?R(CZ) GA102/06/0215 Institutional research plan: CEZ:AV0Z20570509 Keywords : unbalanced voltage supply * voltage-source inverter * pulse width modulation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Scientific Electronic Library Online (English)
Diana Jimena, López Mesa; Guillermo Alberto, Camacho Muńoz; Jaime Oscar, Díaz Chávez; Carlos Alberto, Gaviria López; Gilberto, Bolańos Pantoja.
2009-04-01
Full Text Available Este artículo presenta el diseńo y validación de un nuevo algoritmo de modulación por ancho de pulso (PWM) híbrido que supera el desempeńo armónico de varios algoritmos de modulación empleados en procesos de conversión de potencia en accionamientos eléctricos AC. A partir del análisis armónico de lo [...] s algoritmos PWM más comunes en la literatura, se establece una metodología para diseńar un esquema de modulación híbrido que ofrece un desempeńo armónico superior; este desempeńo es verificado teórica y experimentalmente utilizando el factor de distorsión armónica total F DIST y el índice de distorsión armónica de corriente V WTHD. Abstract in english This paper presents a novel hybrid modulation algorithm which improves the harmonic performance of eight of the most common pulse width modulation (PWM) algorithms for voltage source inverters (VSI) in the electric drive field. From harmonic analysis of these eight algorithms, a methodology was esta [...] blished for designing a hybrid modulation scheme offering superior harmonic performance. The algorithm so designed was validated theoretically by calculating the total harmonic distortion factor F DIST and experimentally by measuring the weighted total harmonic distortion factor V WTHD.
DEFF Research Database (Denmark)
Qu, Hao; Yang, Xijun
2014-01-01
Single-phase voltage source converter (VSC) is an important power electronic converter (PEC), including single-phase voltage source inverter (VSI), single-phase voltage source rectifier (VSR), single-phase active power filter (APF) and single-phase grid-connection inverter (GCI). Single-phase VSC as well as its modulation algorithms is widely used as the fundamental part of large scale PEC’s, having a long list of applications. In the paper, as first, on the basis of the discontinuous pulse-width modulation (DPWM) of three-phase VSC, a new DPWM of single-phase VSR is presented in virtue of zero-sequence component injection, in order to reduce power loss and increased overall efficiency. And then by reconstructing the other two phase input voltages and currents, the transformation from stationary frame (abc) to rotating frame (dq frame) is designed. Finally, a PI regulator based controller for single-phase VSR is analyzed and simulated by means of MATLAB/SIMULINK by using the presented DPWM and dq transformation. The simulation results show the validation of the above DPWM algorithm and control theory.
Diode-Assisted Buck-Boost Voltage-Source Inverters
Gao, Feng; Loh, Poh Chiang; TEODORESCU, Remus; Blaabjerg, Frede
2010-01-01
This paper proposes a number of diode-assisted buck-boost voltage-source inverters with a unique X-shaped diode-capacitor network inserted between the inverter circuitry and dc source for producing a voltage gain that is comparatively higher than those of other buck-boost conversion techniques. Using the diode-assisted network, the proposed inverters can naturally configure themselves to perform capacitive charging in parallel and discharging in series to give a higher voltage multiplication ...
EMI in Induction Motor Drive Fed from IGCT Voltage Source.
Czech Academy of Sciences Publication Activity Database
Bartoš, Stanislav; Jehli?ka, Vladimír; Škramlík, Ji?í; Valouch, Viktor
Cambridge, MA : Electromagnetics Academy, 2007, s. 93-97. ISBN 978-1-934142-02-8. [Progress In Electromagnetics Research Symposium 2007. Prague (CZ), 27.08.2007-30.08.2007] R&D Projects: GA ?R GA102/06/0112 Institutional research plan: CEZ:AV0Z20570509 Keywords : electromagnetic interference (EMI) * induction motor drive * IGCT voltage source inverter Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Energy Technology Data Exchange (ETDEWEB)
Marcelino, M.A.; Silva, G.B.S.; Grandinetti, F.J. [Universidade Estadual Paulista (UNESP), Guaratingueta, SP (Brazil). Fac. de Engenharia; Universidade de Taubate (UNITAU), SP (Brazil)], Emails: abud@feg.unesp.br, gabonini@yahoo.com.br, grandinetti@unitau.br
2009-07-01
This paper presents a technique for speed control three-phase induction motor using the pulse width modulation (PWM), in open loop while maintaining the tension for constant frequency. The technique is adapted from a thesis entitled 'Control of the three-phase induction motor, using discrete PWM generation, optimized and synchronized', where studies are presented aimed at their application in home appliances, to eliminate mechanical parts, replaced by low cost electronic control, thus having a significant reduction in power consumption. Initially the experiment was done with the Intel 80C31 micro controller. In this paper, the PWM modulation is implemented using a PIC micro controller, and the speed control kept a low profile, based on tables, synchronized with transitions and reduced generation of harmonics in the network. Confirmations were made using the same process of building tables, but takes advantage of the program of a RISC device.
DEFF Research Database (Denmark)
Gohil, Ghanshyamsinh Vijaysinh; Maheshwari, Ram Krishan
2015-01-01
Parallel voltage-source converters (VSCs) require an inductive filter to suppress the circulating current. The size of this filter can be minimized by reducing either the maximum value of the flux linkage or the core losses. This paper presents a modified discontinuous pulsewidth modulation (DPWM) scheme to reduce the maximum value of the flux linkage and the core losses in the circulating current filter. In the proposed PWM scheme, the dwell time of an active vector is divided within a half-carrier cycle to ensure simultaneous occurrence of the same zero vectors in both VSCs. A function to decide the ratio of the dwell time of the divided active vector is also presented. The effect of the proposed PWM scheme on the maximum value of the flux linkage and the core losses is analyzed and compared with that of the space vector modulation and 60$^circ$ clamped DPWM schemes. The analytical expressions for the maximum value of the flux linkage are derived for each of these PWM schemes. In addition, the effect of theproposed PWM scheme on the line current ripple and the switching losses is also analyzed and compared. To verify the analysis, experimental results are presented, which prove the effectiveness of the proposed PWM scheme.
DEFF Research Database (Denmark)
Mathe, Laszlo; Lungeanu, Florin
2010-01-01
This paper presents a new fixed carrier frequency random PWM method, where a new type of carrier wave is proposed for modulation. Based on the measurements, it is shown that the spread effect of the discrete components from the motor current spectra is very effective independent of the modulation index. The flat motor current spectrum generates an acoustical noise close to the white noise, which may improve the acoustical performance of the drive. The new carrier wave is easy to implement digitally, without employing any external circuits. The modulation method can be used in open, as well as in closed loop motor control applications.
An imroved design for ZVT DC-DC PWM converters with snubber assisted auxiliary switch
Directory of Open Access Journals (Sweden)
J. Russi
2005-03-01
Full Text Available This paper proposes an improved design to calculate the snubber auxiliary elements of ZVT DC-DC PWM converters with snubber assisted auxiliary switch. The proposed improved design guidelines are based on the reduction of the conduction losses through the auxiliary circuit. It is accomplished by the unique location of the turn-off snubber capacitor, which is shared by both active switches. By means of this improved design guidelines the converter efficiency can be increased. An efficiency comparative analysis is carried out and the experimental results, obtained from 1 kW, 100 kHz laboratory prototypes, show a relevant improvement in converter efficiency compared to the original converter design. In addition, experimental results also confirm that with the improved design the ZVT PWM converters with snubber assisted auxiliary switch can be competitive with ZVT PWM converters with constant auxiliary voltage source (True PWM ZVS pole.Este artigo propőe uma metodologia de projeto aprimorada para determinaçăo dos componentes auxiliares para o conversor ZVT CC-CC PWM snubber assisted auxiliary switch. O procedimento de projeto proposto é baseado na reduçăo das perdas de conduçăo no circuito auxiliar. Isto é somente possível devido ŕ localizaçăo do capacitor snubber de bloqueio, o qual é compartilhado por ambas as chaves ativas. Através do procedimento de projeto proposto o rendimento do conversor pode ser aumentado. Uma análise comparativa do rendimento é apresentada e os resultados experimentais, obtidos de protótipos de laboratório de 1 kW, 100 kHz, mostram uma melhoria relevante em relaçăo ao rendimento apresentado pelo projeto original. Além disso, os resultados experimentais também confirmam que o projeto proposto para o conversor ZVT snubber assisted auxiliary switch torna-o competitivo em relaçăo ao conversor ZVT PWM com fonte auxiliar de tensăo constante (true PWM ZVS pole.
An imroved design for ZVT DC-DC PWM converters with snubber assisted auxiliary switch
Scientific Electronic Library Online (English)
J., Russi; M. L., Martins; H. A., Gründling; H., Pinheiro; J. R., Pinheiro; H. L., Hey.
2005-03-01
Full Text Available Este artigo propőe uma metodologia de projeto aprimorada para determinaçăo dos componentes auxiliares para o conversor ZVT CC-CC PWM snubber assisted auxiliary switch. O procedimento de projeto proposto é baseado na reduçăo das perdas de conduçăo no circuito auxiliar. Isto é somente possível devido [...] ŕ localizaçăo do capacitor snubber de bloqueio, o qual é compartilhado por ambas as chaves ativas. Através do procedimento de projeto proposto o rendimento do conversor pode ser aumentado. Uma análise comparativa do rendimento é apresentada e os resultados experimentais, obtidos de protótipos de laboratório de 1 kW, 100 kHz, mostram uma melhoria relevante em relaçăo ao rendimento apresentado pelo projeto original. Além disso, os resultados experimentais também confirmam que o projeto proposto para o conversor ZVT snubber assisted auxiliary switch torna-o competitivo em relaçăo ao conversor ZVT PWM com fonte auxiliar de tensăo constante (true PWM ZVS pole). Abstract in english This paper proposes an improved design to calculate the snubber auxiliary elements of ZVT DC-DC PWM converters with snubber assisted auxiliary switch. The proposed improved design guidelines are based on the reduction of the conduction losses through the auxiliary circuit. It is accomplished by the [...] unique location of the turn-off snubber capacitor, which is shared by both active switches. By means of this improved design guidelines the converter efficiency can be increased. An efficiency comparative analysis is carried out and the experimental results, obtained from 1 kW, 100 kHz laboratory prototypes, show a relevant improvement in converter efficiency compared to the original converter design. In addition, experimental results also confirm that with the improved design the ZVT PWM converters with snubber assisted auxiliary switch can be competitive with ZVT PWM converters with constant auxiliary voltage source (True PWM ZVS pole).
Parallel operation of voltage-source converters: issues and applications
Energy Technology Data Exchange (ETDEWEB)
Almeida, F.C.B.; Silva, D.S. [Federal University of Juiz de Fora (UFJF), MG (Brazil)], Emails: felipe.brum@engenharia.ufjf.br, salomaoime@yahoo.com.br; Ribeiro, P.F. [Calvin College, Grand Rapids, MI (United States); Federal University of Juiz de Fora (UFJF), MG (Brazil)], E-mail: pfribeiro@ieee.org
2009-07-01
Technological advancements in power electronics have prompted the development of advanced AC/DC conversion systems with high efficiency and flexible performance. Among these devices, the Voltage-Source Converter (VSC) has become an essential building block. This paper considers the parallel operation of VSCs under different system conditions and how they can assist the operation of highly complex power networks. A multi-terminal VSC-based High Voltage Direct Current (M-VSC-HVDC) system is chosen to be modeled, simulated and then analyzed as an example of VSCs operating in parallel. (author)
Smirnov, Aleksandr O.; Matveenko, Sergei G.; Semenov, Sergei K.; Semenova, Elena G.
2014-01-01
In the article, we describe three-phase finite-gap solutions of the focusing nonlinear Schr\\"odinger equation and Kadomtsev-Petviashvili and Hirota equations that exhibit the behavior of almost-periodic "freak waves". We also study the dependency of the solution parameters on the spectral curves.
Three-phase electric drive with modified electronic smoothing inductor
DEFF Research Database (Denmark)
Singh, Yash Veer; Rasmussen, Peter Omand
2010-01-01
This paper presents a three-phase electric drive with a modified electronic smoothing inductor (MESI) having reduced size of passive components. The classical electronic smoothing inductor (ESI) is able to control a diode bridge output current and also reduce not only mains current harmonics but also output voltage ripple. ESI performs the function of an inductor that has controlled variable impedance. MESI requires active switches with lower ratings than ESI and has the same performance. In MESI, an active voltage source realized by a low-voltage switch-mode converter stage is inserted in series with DC-link capacitor. This increases power factor (PF) and reduces the total harmonic distortions (THDs) in current at mains. Input currents of the diode bridge which usually show high peak amplitudes are converted into a 120° rectangular shape which ideally results in a total PF of 0.955 and THDs of 31%, by electronic smoothing techniques.
Directory of Open Access Journals (Sweden)
Valantina Stephen
2012-01-01
Full Text Available This study proposes different configurations of PWM techniques for harmonic reduction and improvement of fundamental peak voltage. For providing adjustable frequency power to industrial applications, three-phase inverter is preferred. The general aim of this study is to reduce the third order harmonics and improve the Harmonic Spread Factor by different PWM techniques using matlab modelsim cosimulation. The gating signals to the inverter are produced by means of SPWM, RFPWM, Third Harmonic Injection (THI and Hybrid Random Frequency THIPWM. FPGA because of its suitability in time critical systems it is used to produce gating signals to the switches in a three-phase bridge inverter. This study will provide the insight of trends and technologies of Third Order Harmonic Elimination and improvement of HSF using different PWM techniques. In addition, a performance comparison of proposed methods with modified PWM methods is also provided. The result of the proposed work shows that there is improvement in fundamental voltage, THD, HSF when a combination of RF-THI PWM techniques is used.
Generalized SVPWM Algorithm for Two Legged Three Phase Multilevel Inverter
Directory of Open Access Journals (Sweden)
Devisree Sasi
2013-07-01
Full Text Available This paper establishes the inherent fractal structure in the space vector representation of two legged three phase multilevel inverters. The established fractal structure is utilized to propose a generalized algorithm for space vector PWM generation for two legged multilevel inverters. The voltage space vectors of higher level inverters can be generated from the voltage space vectors of equivalent 2-level inverter. The proposed algorithm can be easily extended to n-level inverters without any computational complexity and it doesn’t use any look up table for sector identification. The paper explains the proposed method for 5-level inverter and simulation results are presented for 2-level, 3-level and 5-level configurations in MATLAB/SIMULINK.
Three-phase phononic materials
Rohan E.; Cimrman R.
2009-01-01
We consider a strongly heterogeneous material consisting of three phases: an elastic matrix, medium-size inclusions periodically embedded in the elastic matrix; these inclusions are constituted by small rigid inclusions coated by a very compliant material. The dependence on scale of elasticity coefficients of the deformable medium-size inclusions is treated in the context of linear elasticity by the homogenization procedure providing a limit model that inherently describes band gaps in acoust...
DESIGN THREE PHASE OVERCURRENT RELAYS
Directory of Open Access Journals (Sweden)
Mohammed Y Suliman,
2013-05-01
Full Text Available A new design of three phase overcurrent relay described in this paper. The performance of the new design shows the ability to obtain any shape of characteristic with high accuracy and distinguish between transient and steady state fault. This design used more precise and flexible model Sachdev linear model for get any characteristic, also fast measurement theory to measure load current for less than half cycle and good hardware system design controlled by Pentium version 4 processor.
Microprocessor based area sampling technique for neutral point clamped PWM inverter
Shekhawat, S. S.; Dhyanchand, J.; Thollot, P.
Recent advances in microelectronics, power devices and other technological areas have made it possible to design and develop three-phase, variable frequency, variable voltage, switching power inverters to drive three-phase ac motor and for a variety of other applications. In these systems, the microprocessor is playing an increasingly larger role for generating complex control signals, which were previously not possible by conventional linear and digital IC's. This paper discusses a microprocessor based switching control signal for three phase neutral point clamped pulse width modulated inverter which has been designed and developed to minimize the lower harmonics in the output voltage. These complex PWM switching signals (PWM patterns) can be computed and generated in real time with good harmonic spectrum by using fast microprocessors.
Mitigation of Lower Order Harmonics with Filtered Svpwm In Multiphase Voltage Source Inverters
Directory of Open Access Journals (Sweden)
K. Uday Kiran
2014-08-01
Full Text Available Multi-phase machines and drives is a topic of growing relevance in recent years, and it presents many challenging issues that still need further research. This is the case of multi-phase space vector pulse width modulation (SVPWM, which shows not only more space vectors than the standard three-phase case, but also new subspaces where the space vectors are mapped. In the digital implementation, multiphase reference voltages are sampled and fed into the digital modulator to produce gating signals at a constant clock rate f. This means a finite pulse-width resolution because the gating state transition can only occur at some specific time instants depending on frequency. This results in a deviation of produced phase voltages from the desired phase voltages, i.e., increasing harmonic distortion especially for a small modulation index signal. In the present paper a filtered space-vector pulse-width modulation (SVPWM considering finite pulse-width resolution is proposed to produce a switching sequence with reduced baseband harmonics for multiphase voltage source inverters (VSI. This is achieved by incorporating a pseudo feedback loop regarding weighted voltage difference between desired and produced phase voltages.
Multilevel cascade voltage source inverter with separate DC sources
Peng, F.Z.; Lai, J.S.
1997-06-24
A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations. 15 figs.
Multilevel cascade voltage source inverter with seperate DC sources
Peng, Fang Zheng; Lai, Jih-Sheng
2001-04-03
A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.
Multilevel cascade voltage source inverter with seperate DC sources
Peng, Fang Zheng (Knoxville, TN); Lai, Jih-Sheng (Blacksburg, VA)
2002-01-01
A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.
High-Speed Fuses in IGBT based Voltage Source Converters
DEFF Research Database (Denmark)
Iov, Florin; Blaabjerg, Frede
2005-01-01
The demand for protection of power electronic applications has during the last couple of years increased regarding the high-power IGBT modules. Even with an active protection, a high power IGBT still has a risk of exhibiting a violent rupture in the case of a fault if IGBT fuses do not protect it. By introducing fuses into voltage source converters a better protection of IGBTs can be achieved. This paper is a complete overview of a research project carried out in cooperation by Aalborg University, Denmark and Cooper Bussmann International. This paper discusses three main issues regarding the IGBT fuse protection. First, the problem of adding inductance in the DC-link circuit is treated, second a short discussion of the protection of the IGBT module is done, and finally, the impact of the high frequency loading on the current carrying capability of the fuses is presented.
Power Quality Improvement using Dual Voltage Source Converter Based DVR
Directory of Open Access Journals (Sweden)
A.Suresh
2014-01-01
Full Text Available In any power system, The modelling and simulation of three and seven-level Dual Voltage Source Converter based dynamic voltage restorer (DVR aimed at correcting the supply voltage sag/swell and interruption in low voltage distribution networks. The proposed design models of DVSC based DVR are expected to be most powerful solutions to minimize supply voltage disturbances of the sensitive loads. A DVR is a VSC based power electronics device connected in series between the supply and the critical loads, which are to be protected from the supply side voltage quality problems, other than outages, by injecting the required compensating voltage through DVR into the distribution line. The proposed models of DVR together with the controllers are simulated by using MAT LAB Simulink and the results are presented to assess the performance of each device.
A classification methodology for zero-voltage transition PWM converters
Directory of Open Access Journals (Sweden)
M. L. Martins
2005-03-01
Full Text Available This paper presents a classification methodology of the ZVT soft-transition technique, which is based on different ways of implementation of the auxiliary circuit voltage source. The merits and limitations of each class are presented and their key features and characteristics are discussed and experimentally analyzed on the 1kW/100kHz laboratory prototypes. By means of the proposed classification criteria, any ZVT topology can be classified, even the unpublished ones. Additionally, an overview of the main ZVT PWM converters proposed in the last decades is also presented.Este artigo propőe uma metodologia de classificaçăo para a técnica de comutaçăo suave conhecida como ZVT. Esta classificaçăo é baseada nos diferentes modos de implementaçăo da fonte auxiliar de tensăo. Os méritos e limitaçőes de cada classe săo apresentados. As particularidades e características de cada classe săo discutidas e analisadas experimental-mente em protótipos de laboratório de 1kW/100kHz. Por meio do critério de classificaçăo proposto, qualquer topologia ZVT pode ser classificada, mesmo aquelas inéditas na literatura. Além disso, é apresentada uma visăo geral dos principais con-versores ZVT PWM propostos nas últimas décadas.
Review of multilevel voltage source inverter topologies and control schemes
International Nuclear Information System (INIS)
In this study, the most common multilevel inverter topologies and control schemes have been reviewed. Multilevel inverter topologies (MLIs) are increasingly being used in medium and high power applications due to their many advantages such as low power dissipation on power switches, low harmonic contents and low electromagnetic interference (EMI) outputs. The selected switching technique to control the inverter will also have an effective role on harmonic elimination while generating the ideal output voltage. Intensive studies have been performed on carrier-based, sinusoidal, space vector and sigma delta PWM methods in open loop control of inverters. The selection of topology and control techniques may vary according to power demands of inverter. This paper and review results constitute a useful basis for matching of inverter topology and the best control scheme according to various application areas.
Low-cost PWM speed controller for an electric mini-baja type vehicle
Samuel Euzédice de Lucena; Márcio Abud Marcelino; Francisco José Grandinetti
2007-01-01
This paperwork presents a Pulse Width Modulation (PWM) speed controller for an electric mini-baja-type car. A battery-fed 1-kW three-phase induction motor provides the electric vehicle traction. The open-loop speed control is implemented with an equal voltage/frequency ratio, in order to maintain a constant amount of torque on all velocities. The PWM is implemented by a low-cost 8-bit microcontroller provided with optimized ROM charts for distinct speed value implementations, synchronized tra...
DEFF Research Database (Denmark)
Mathe, Laszlo; Cornean, Horia
2011-01-01
Pulse width modulation (PWM) is a key element of a voltage source inverter, inverter which is widely used for electric motor control and electric energy conversion. Several PWM methods have been proposed in the literature, focusing on performance, ease of implementation, and maximization of the transfer ratio. The difference between most of the proposed modulation methods like sine-triangular, SVM, and 120 - 60 - 30 Discontinuous PWM consists in the redistribution of the time-length applied for the zero voltage vectors during a fundamental frequency period. This paper presents a unified analytical equation for determining the theoretical spectra components for all the carrier based PWM methods with redistributed zero space vector time-length using the double Fourier integral analysis. The proposed unified equation can also be used for determination of the phase and line-to-line voltage spectra when the modulator works in over-modulation region. Moreover, the effect of the DC-link voltage ripple on the line-to-line voltage spectra is also considered. The experimental results show a very good agreement with the theoretically calculated spectra.
Power spectra of a three-phase inverter with random pulse width modulation modes
Energy Technology Data Exchange (ETDEWEB)
Kwok, S.T.C.
1993-01-01
For three-phase power inversion, the voltage control is realized by means of pulse width modulation (PWM) of the switching variables which represent the control signals for the individual phases of the inverter. Analysis of the harmonic power spectra of the three-phase voltage-controlled inverter with randomized lead-lag modes of operation is presented. In these modes, the pulses of switching variables are either leading- or lagging-edge modulated. The randomized PWM technique provides non-repetitive switching patterns which result in spreading of distinct harmonic power over a wider frequency range. The circuit description of the randomized PWM technique is presented and three kinds of inverter control functions are introduced for explaining the principle of randomized pulse width modulation. The randomized pulse position technique is also discussed and analyzed. Closed-form expressions are given which describe the output spectra of the power inverter. MATLAB plots are provided to verify the experimental results based on those of Trzynadlowski and Legowski (1989, 1990). Program listings for calculating the spectra of a single phase output of a voltage controlled inverter are included. 30 refs., 41 figs.
Performance of voltage source multilevel inverter - fed induction motor drive using Simulink
Directory of Open Access Journals (Sweden)
Neelashetty Kashappa
2011-06-01
Full Text Available This paper deals with performance of voltage source multilevel inverter-fed induction motor drive. A Voltage source inverter (VSI is compared with multilevel inverter. A conventional Voltage Source Inverter-fed induction motor drive is modeled and simulated using Matlab/ Simulink and the results are presented. Multilevel inverter employing Selective Harmonic Elimination (SHE method is also simulated and the corresponding results are presented. The FFT spectrum for the outputs is analyzed to study the reduction in harmonics.
Performance of voltage source multilevel inverter - fed induction motor drive using Simulink
Neelashetty Kashappa; Ramesh Reddy K.
2011-01-01
This paper deals with performance of voltage source multilevel inverter-fed induction motor drive. A Voltage source inverter (VSI) is compared with multilevel inverter. A conventional Voltage Source Inverter-fed induction motor drive is modeled and simulated using Matlab/ Simulink and the results are presented. Multilevel inverter employing Selective Harmonic Elimination (SHE) method is also simulated and the corresponding results are presented. The FFT spectrum for the outputs is analyzed to...
Scientific Electronic Library Online (English)
Robinson F. de, Camargo; Fernando, Botterón; Humberto, Pinheiro; José R., Pinheiro; Hilton, Gründling; Hélio, Hey.
2004-09-01
Full Text Available Este artigo propőe dois novos algoritmos de limitaçăo para inversores de tensăo trifásicos a quatro braços. Estes baseiam-se na limitaçăo do vetor de comando dentro da regiăo de operaçăo linear do inversor. O primeiro algoritmo utiliza um elipsóide inscrito no dodecaedro definido pelas extremidades [...] dos possíveis vetores de comutaçăo do inversor, e o segundo é baseado nos planos limites desse poliedro. Uma descriçăo detalhada, abordando os principais pontos requeridos para a implementaçăo digital, da modulaçăo space vector e dos algoritmos de limitaçăo săo apresentados. Ainda, as tensőes de saída e as correntes nos indutores săo dinamicamente reguladas, por meio de servo controladores MIMO em eixos síncronos dq0. Estes controladores săo projetados usando a técnica do regulador linear quadrático discreto de regime permanente, o qual assegura estabilidade para o sistema em toda a faixa de operaçăo. Além disso, para prover transiçőes suaves entre os diferentes modos de operaçăo do inversor, săo propostos algoritmos MIMO năo lineares para limitar a sobrecarga da açăo integral, quando o vetor de comando for limitado, e atualizar dinamicamente as variáveis dos servo controladores. Finalmente, săo apresentados resultados experimentais obtidos de um protótipo de 15 kVA, totalmente controlado por um DSP TMS320F241, para validar os algoritmos propostos e demostrar o desempenho do sistema como um todo. Abstract in english This paper proposes two novel limiting algorithms for three-phase four-leg voltage source inverters to constrain the command vector inside the dodecahedron defined by the boundaries of the inverter linear operating range. The first algorithm uses an inscribed ellipsoid on the dodecahedron, and the s [...] econd one is based on the polyhedron boundary planes. A detailed description, with the key points required for a digital implementation of space vector and limiting algorithms, is given. In addition, the output voltages and the inductors currents are dynamically regulated by means of MIMO servo controller in dq0 coordinates. These controllers are designed using optimal discrete linear quadratic regulator technique, which ensures stability for the system at all operating conditions. In order to provide smooth transitions among the different modes of operation, nonlinear MIMO anti-windup algorithms are proposed to dynamically update the controllers servo variables. Finally, experimental results on a 15 kVA PWM inverter fully controlled by a DSP controller, TMS320F241, has been used to validate the feasibility of the proposed algorithm and to demonstrate the performance of the overall system.
Fault Current Limiter by Series Connected Voltage Source Inverter
Hojo, Masahide; Kuroe, Norihito; Ohnishi, Tokuo
In recent years, various types of fault current limiter (FCL) have been developed, because installation of the FCL will bring a lot of benefits to power system operation. Power system controllers based on a concept of Flexible AC Transmission Systems (FACTS) can also be applicable as the FCL with growing power ratings of them. Such FCLs are expected to contribute power system stabilization or power quality enhancement in addition to fault current limitation. Authors have developed a new type of FCL, which consists of a series reactor and a self-commutated voltage source inverter connected in series with a power distribution line by a coupling transformer. In case of a system fault, the FCL will insert a sufficiently large inductance in series with the distribution line by both the series reactor and the inverter, then it will reduce the fault current. On the other hand, the inverter compensates a voltage drop across the series reactor in a standby mode. As a result, the FCL behaves like a negligible impedance in the standby mode. One of the distinctive features of the FCL is a simple configuration because its control strategy does not require an active power source. In addition, inverter voltage rating of the proposed FCL can be reduced by installing the series reactor as compared with other converter-based FCLs. The aim of this paper is to evaluate the operating characteristics of the FCL with both simulation and experimental studies.
IGBT Fuses for Protection Against Explosion in Voltage Source Converters
DEFF Research Database (Denmark)
Blaabjerg, Frede; Iov, Florin
2004-01-01
The consequences of electrical faults can be severe; not only to the equipment, but also in the worse case, to people if safety principles are not observed. Every year new applications based on DC-link Voltage Source Converters are added and the demand for protection of power electronics increases regarding the high-power IGBT modules. Due to the fact that the power level increases more energy is stored in the DC-link and even with an active protection, a high-power IGBT still has a risk of case rupture (explode) when a circuit failure condition occurs. A possible solution is a protection of the converter with standard High Speed Fuses or High Speed IGBT fuses. It is discussed that protection can be achieved by introduction of IGBT fuse located in the DC-link. Experiments show that explosion can be avoided by use of High Speed Fuse protection and the added inductance of standard High Speed- and IGBT Fuses in the DC-link is investigated. The current distribution in fuses is discussed when high frequency components are present in the load current. Further it is discussed how the extra cost for IGBT fuses may be balanced by ease of maintenance and less downtime of manufacturing equipment.
Zidani, Fatiha; DIALLO, Demba; Benbouzid, Mohamed; Naďt-Saďd, Rachid
2008-01-01
This paper investigates the use of fuzzy logic for fault detection and diagnosis in a pulsewidth modulation voltage source inverter (PWM-VSI) induction motor drive. The proposed fuzzy technique requires the measurement of the output inverter currents to detect intermittent loss of firing pulses in the inverter power switches. For diagnosis purposes, a localization domain made with seven patterns is built with the stator Concordia current vector. One is dedicated to the healthy domain and the ...
A modified two-level three-phase quasi-soft-switching inverter
DEFF Research Database (Denmark)
Liu, Yusheng; Wu, Weimin
2014-01-01
A traditional Voltage Source Inverter (VSI) has higher efficiency than a Current Voltage Source (CSI) due to the less conduction power loss. However, the reverse recovery of the free-wheeling diode limits the efficiency improvement for the silicon devices based hard-switching VSI. The traditional quasi-soft-switching inverter can alternate between VSI and CSI by using a proper control scheme and thereby reduce the power losses caused by the reverse recovery of the free-wheeling diode. Nevertheless, slightly extra conduction power loss of the auxiliary switch is also introduced. In order to reduce the extra conduction power loss and the voltage stress across the DC-link capacitor, a modified two-level three-phase quasi-soft-switching inverter is proposed by using a SiC MOSFET instead of an IGBT. The principle of the modified two-level three-phase quasi-soft-switching inverter is analyzed in detail. And the performance is verified through simulations and experiments on a 5 kW/380 V three-phase prototype.
P.Narasimhulu; N.Sreekanth*
2014-01-01
A reduced rating voltage-source converter with a zig-zag transformer as a distribution static compensator is proposed for power-quality improvement in the three-phase four-wire distribution system. The source voltages in the distribution systems are also experiencing power quality problems, such as harmonics, unbalance, flicker, sag, swell, etc. The distribution static compensator (DSTATCOM) is proposed for compensating power quality problems in the current, and the dynamic vo...
Software Phase Lock Loops Applied in Three-Phase PWM Rectifier.
Czech Academy of Sciences Publication Activity Database
Šimek, Petr; Škramlík, Ji?í; Valouch, Viktor; Bejvl, Martin
Košice : Technical University of Košice, 2011, s. 227-232. ISBN 978-80-553-0734-3. [International Conference on Electrical Drives and Power Electronics - EDPE 11 /17./. Stará Lesná, The High Tatras (SK), 28.10.2011-30.10.2011] R&D Projects: GA MPO(CZ) FR-TI1/330 Institutional research plan: CEZ:AV0Z20570509 Keywords : phase lock loop * unsymmetrical voltage system * harmonics Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Three-phase power supply, output 60v and 100a, with unit power factor and low RFI level
Directory of Open Access Journals (Sweden)
Joăo Batista Vieira Júnior
2003-01-01
Full Text Available This paper presents a three-phase rectifier, unit power factor, non-dissipative commutation in DC-DC converter and synchronized control in frequency, working with 89% of global efficiency and low level do RFI. The proposed structure allows the operation with high switching frequency. The output voltage is controlled by PWM with a constant frequency. The operation principle, theoretical analysis from DC converter, relevant equations, current balance control technique and experimental results, are shown in this paper.
Three-Phase Grid-Connected of Photovoltaic Generator Using Nonlinear Control
DEFF Research Database (Denmark)
Yahya, A.; El Fadil, H.
2014-01-01
This paper proposes a nonlinear control methodology for three phase grid connected of PV generator. It consists of a PV arrays; a voltage source inverter, a grid filter and an electric grid. The controller objectives are threefold: i) ensuring the Maximum power point tracking (MPPT) in the side of PV panels, ii) guaranteeing a power factor unit in the side of the grid, iii) ensuring the global asymptotic stability of the closed loop system. Based on the nonlinear model of the whole system, the controller is carried out using a Lyapunov approach. It is formally shown, using a theoretical stability analysis and simulation results that the proposed controller meets all the objectives.
Scientific Electronic Library Online (English)
O., Malik; F. J., De la Hidalga-W..
2013-02-01
Full Text Available Cualquier sistema de instrumentación consiste de tres elementos: el sensor o dispositivo de entrada, el procesador de seńales, y el receptor o dispositivo de salida. Diversos sistemas de control automático o con retroalimentación requieren una seńal eléctrica de salida en forma de pulsos con modulac [...] ión en su ancho (PWM). Generalmente la seńal analógica de salida se transforma usando un convertidor de seńal PWM. En este trabajo se muestra que una seńal de salida PWM, con una razón ancho-de-pulso/período (duty cycle) controlado por la intensidad de la iluminación, puede obtenerse directamente utilizando un circuito que contiene un capacitor metal (compuerta semitransparente) -óxido-semiconductor (MOS-C) conectado en serie con una fuente de DC y un generador de funciones que proporciona un voltaje periódico en forma de dientes de sierra. Internamente, la conversión de seńal a PWM se logra explotando los procesos físicos fuera de equilibrio que se presentan dentro del sustrato de silicio del MOS-C. La seńal cuadrada PWM, cuya amplitud está limitada a 10-20 V, se obtiene mediante la amplificación de la seńal de transductor usando un amplificador estándar de transimpedancia de 60 dB. La seńal de salida amplificada presenta una forma de onda PWM positiva y negativa que pueden separarse usando diodos. La razón ancho-de-pulso/período de la parte positiva es proporcional a la intensidad de la iluminación, mientras que la parte negativa es inversamente proporcional a dicha intensidad. La frecuencia de operación de este instrumento se encuentra en el rango de 1 Hz hasta algunos kilohertz. La razón ancho-de-pulso/período de la seńal de salida PWM varía entre 2 y 98% cuando la potencia de la iluminación es del orden de microwatts. Este nuevo transductor o sensor podría ser útil para aplicaciones en control automático, en robótica, control de iluminación, sistemas de retroalimentación, y para la detección óptica de posición sin contacto para mediciones de centrado y anulación. Finalmente, se presenta una descripción detallada de los principios físicos y de operación de este nuevo transductor. Abstract in english This work shows that the direct PWM output electric signal, with a duty cycle controlled by light intensity, can be obtained using a circuit containing a saw-tooth voltage generator connected in series with a dc voltage source and a metal (semitransparent gate) oxide semiconductor capacitor (MOS-C). [...] The internal PWM signal conversion occurs by the use of non-equilibrium physical processes in the semiconductor substrate of the MOS-C. The 10-20 V amplitude limited square PWM output signal is obtained by the amplification of the sensor signal with a standard 60 dB transimpedance amplifier. The amplified output signal presents positive and negative PWM waveforms that can be easily separated using diodes. The duty of the positive part is proportional to the light intensity, whereas the negative part is inversely proportional to the intensity. The frequency operating range of this proposed instrument varies from 1 Hz to a few kilohertz. The duty cycle of the PWM output signal varies from 2% to 98% when the incident light intensity varies in the microwatts range. These new transducers or sensors could be useful for automatic control, robotic applications, dimmer systems, feedback electronic systems, and non-contact optical position sensing for nulling and centering measurements.
Directory of Open Access Journals (Sweden)
Robinson F. de Camargo
2005-12-01
Full Text Available Este trabalho desenvolve um procedimento de projeto sistemático para o controle das correntes de entrada e da tensăo de saída de retificadores PWM trifásicos. Primeiramente é apresentado o modelo discreto em eixos síncronos dq do retificador PWM trifásico com filtro de entrada L, o qual leva em conta o tempo de processamento necessário para a implementaçăo em tempo real. A operaçăo do retificador com resposta de tempo mínimo é obtida utilizando o método de desacoplamento por retroaçăo de estados no domínio discreto, sem a necessidade de um controlador de corrente adicional no eixo d. Além disso, săo desenvolvidos servos controladores de corrente e tensăo a fim de garantir fator de deslocamento unitário e regulaçăo de tensăo no barramento CC respectivamente. Finalmente, resultados experimentais săo apresentados, a fim de validar o procedimento proposto e verificar o desempenho do retificador PWM trifásico.This paper develops a systematic design procedure based on discrete decoupling by state feedback applied to three-phase PWM rectifiers. A discrete model for synchronous frame is developed for three-phase PWM rectifier with an L filter. This model takes into account the computational delays presents in the discrete implementation. Deadbeat response is obtaining without the requirement of a current controller in the axis d. Moreover, discrete servo controllers to ensure unit displacement power factor and regulated DC link voltage are developed. Finally, experimental results are presented to demonstrate the feasibility of the proposed procedure, algorithms and the performance of the overall system.
An Integrated Inductor for Parallel Interleaved VSCs and PWM Schemes for Flux Minimization
DEFF Research Database (Denmark)
Gohil, Ghanshyamsinh Vijaysinh; Bede, Lorand
2015-01-01
The interleaving of the carrier signals of the parallel Voltage Source Converters (VSCs) can reduce the harmonic content in the resultant switched output voltages. As a result, the size of the line filter inductor can be reduced. However, in addition to the line filter, an inductive filter is often required to suppress the circulating current. The size of the system can be reduced by integrating these two inductors in a single magnetic component. A integrated inductor, which combines the functionality of both the line filter inductor and the circulating current filter inductor is presented. The PulseWidth Modulation (PWM) schemes to reduce the flux in some parts of the integrated inductor are also analyzed. The flux reduction achieved by using these schemes is demonstrated by comparing these schemes with the conventional space vector modulation and the $60\\degree$ clamped discontinuous PWM scheme. The impact of these PWM schemes on the harmonic performance is also discussed. Simulation and experimental results are presented to validate the analysis.
Inverted sine carrier for fundamental fortification in PWM inverters and FPGA based implementations
Directory of Open Access Journals (Sweden)
Jeevananthan S.
2007-01-01
Full Text Available This paper deals with a novel natural sampled pulse width modulation (PWM switching strategy for voltage source inverter through carrier modification. The proposed inverted sine carrier PWM (ISCPWM method, which uses the conventional sinusoidal reference signal and an inverted sine carrier, has a better spectral quality and a higher fundamental component compared to the conventional sinusoidal PWM (SPWM without any pulse dropping. The ISCPWM strategy enhances the fundamental output voltage particularly at lower modulation index ranges while keeping the total harmonic distortion (THD lower without involving changes in device switching losses. The presented mathematical preliminaries for both SPWM and ISCPWM give a conceptual understanding and a comparison of the strategies. The detailed comparison of the harmonic content and fundamental component of the ISCPWM output for different values of modulation index with the results obtained for the SPWM is also presented. Finally, the proposed modulator has been implemented in field programmable gate array (FPGA- Xilinx Spartan 3 and tested with the proto-type inverter.
Directory of Open Access Journals (Sweden)
Rasoul Shalchi Alishah
2015-06-01
Full Text Available In recent, several numbers of multilevel inverter structures have been introduced that the numbers of circuit devices have been reduced. This paper introduces a new structure for multilevel inverter which can be used in high-power applications. The proposed topology is based on cascaded connection of basic units. This topology consists of minimum number of circuit components such as IGBT, gate driver circuit and antiparallel diode. For proposed topology, two methods are presented for determination of dc voltage sources values. Multi-carrier PWM method for 25-level proposed topology is used. Verification of the analytical results is done using MATLAB simulation.
Active control of flying capacitor currents in multilevel voltage-source inverters.
Czech Academy of Sciences Publication Activity Database
Kokeš, Petr; Semerád, Radko
2013-01-01
Ro?. 58, ?. 4 (2013), s. 393-410. ISSN 0001-7043 Institutional support: RVO:61388998 Keywords : voltage source inverter (VSI) * multilevel inverter * flying capacitor Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Scalar Controlled Boost PWM Rectifier for Micro Wind Energy Systems
Directory of Open Access Journals (Sweden)
J. Chelladurai
2015-05-01
Full Text Available Uses of Permanent Magnet Synchronous Generators (PMSG are increasing in variable speed micro-Wind Energy Conversion Systems (WECS. In stand-alone or grid-connected Micro-WECS, extraction of maximum power is vital. To extract maximum power output and to obtain a constant DC bus voltage from variable magnitude and variable frequency voltage output of PMSG and generally a two stage scheme namely i conventional diode bridge rectifier and ii DC-DC Boost/Buck/Buck-Boost converters are used. In this study, a single stage Scalar Controlled PWM (SCPWM Boost Rectifier is proposed in order to minimize the current harmonics and to improve the power factor on source side. The modeling and simulation of PMSG based wind generator and SCPWM Boost rectifier was developed in MATLAB. The harmonic content in the input current waveform of the proposed SCPWM rectifier is compared with the conventional three-phase bridge rectifier. The Simulation results show the effectiveness of the PWM Boost rectifier in terms of effective utilization of source, improved efficiency and harmonic mitigation for PMSG based Wind Generator. Simulation results demonstrate the effectiveness of the proposed system in reducing the current and voltage THD on source side.
PWM Inverter control and the application thereof within electric vehicles
Geppert, Steven (Bloomfield Hills, MI)
1982-01-01
An inverter (34) which provides power to an A.C. machine (28) is controlled by a circuit (36) employing PWM control strategy whereby A.C. power is supplied to the machine at a preselectable frequency and preselectable voltage. This is accomplished by the technique of waveform notching in which the shapes of the notches are varied to determine the average energy content of the overall waveform. Through this arrangement, the operational efficiency of the A.C. machine is optimized. The control circuit includes a micro-computer and memory element which receive various parametric inputs and calculate optimized machine control data signals therefrom. The control data is asynchronously loaded into the inverter through an intermediate buffer (38). In its preferred embodiment, the present invention is incorporated within an electric vehicle (10) employing a 144 VDC battery pack (32) and a three-phase induction motor (18).
Czech Academy of Sciences Publication Activity Database
Chomát, Miroslav; Schreier, Lud?k
Piscataway, NJ : IEEE Service Center, 2003, s. 869-875. ISBN 0-7803-7818-0. [IEEE International Electric Machines and Drives Conference(IEMDC). Madison, Wisconsin (US), 01.06.2003-04.06.2003] R&D Projects: GA ?R GA102/02/0554 Institutional research plan: CEZ:AV0Z2057903 Keywords : unbalanced voltage supply * control method for DC link voltage ripple cancellation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
DEFF Research Database (Denmark)
Kouchaki, Alireza; Nymand, Morten
This paper studies the inductor design for three-wire and four-wire power factor correction converter (PFC). Designing the efficient inductor for this converter (regardless of connecting the midpoint to the ground) requires a comprehensive knowledge of the inductor current and voltage behavior. This paper investigates how changing three-wire PFC to four-wire counterpart influences the inductor design in terms of size, losses, and overall efficiency of the converter. Therefore, the inductor current and voltage waveforms are analyzed and generalized in both cases for one switching cycle to build a foundation for comparison. Accordingly, the analyses are able to interpret the differences between both configurations and explain the core losses and the copper losses of inductors, especially those caused by the high frequency ac current ripple. Finally, two inductors are designed for a 5 kW PFC experimental setup. The experimental results which are performed for three-wire and four-wire PFC show a good match with the analyses.
Assessment of the impact that individual voltage source has on a generator’s stability
DEFF Research Database (Denmark)
Dmitrova, Evgeniya; Jóhannsson, Hjörtur
2012-01-01
This paper presents an approach for splitting equivalent Thevenin voltage into components induced by each voltage source in the reduced grid. Thevenin equivalent representation of the system is sometimes used for stability assessment of a given generator, where the Thevenin voltage is one of the key variables affecting the stability conditions. Thevenin voltage is formed by components induced by each voltage source in the grid, while depending on topology and system parameters, the impact of these components on the equivalent Thevenin voltage Eth might vary considerably. This paper demonstrates how the impact of individual voltage source to the Eth might be defined utilizing system admittance matrix. Knowledge about alternation of Eth while applying changes to either admittance matrix or generators’ excitation and torque gives promising perspective for determination of effective countermeasures aimed on instability prevention. Suggested approach for Eth decomposition is applied to the IEEE 30 bus test system.
Low-cost PWM speed controller for an electric mini-baja type vehicle
Scientific Electronic Library Online (English)
Samuel Euzédice de, Lucena; Márcio Abud, Marcelino; Francisco José, Grandinetti.
2007-03-01
Full Text Available This paperwork presents a Pulse Width Modulation (PWM) speed controller for an electric mini-baja-type car. A battery-fed 1-kW three-phase induction motor provides the electric vehicle traction. The open-loop speed control is implemented with an equal voltage/frequency ratio, in order to maintain a [...] constant amount of torque on all velocities. The PWM is implemented by a low-cost 8-bit microcontroller provided with optimized ROM charts for distinct speed value implementations, synchronized transition between different charts and reduced odd harmonics generation. This technique was implemented using a single passenger mini-baja vehicle, and the essays have shown that its application resulted on reduced current consumption, besides eliminating mechanical parts.
Methods, systems and apparatus for adjusting duty cycle of pulse width modulated (PWM) waveforms
Gallegos-Lopez, Gabriel; Kinoshita, Michael H; Ransom, Ray M; Perisic, Milun
2013-05-21
Embodiments of the present invention relate to methods, systems and apparatus for controlling operation of a multi-phase machine in a vector controlled motor drive system when the multi-phase machine operates in an overmodulation region. The disclosed embodiments provide a mechanism for adjusting a duty cycle of PWM waveforms so that the correct phase voltage command signals are applied at the angle transitions. This can reduce variations/errors in the phase voltage command signals applied to the multi-phase machine so that phase current may be properly regulated thus reducing current/torque oscillation, which can in turn improve machine efficiency and performance, as well as utilization of the DC voltage source.
Scientific Electronic Library Online (English)
Leandro, Michels; Robinson F. de, Camargo; Fernando, Botterón; Humberto, Pinheiro.
2005-06-01
Full Text Available Este artigo apresenta uma metodologia sistematizada de projeto de filtros de saída de segunda ordem para inversores que sintetizam tensőes senoidais através de modulaçăo por largura de pulso (PWM) digital. O propósito desta metodologia é o de determinar os parâmetros do filtro que assegure a especif [...] icaçăo da máxima taxa de distorçăo harmônica total (THD) admissível nas tensőes de saída do inversor PWM, para cargas lineares e năo-lineares. A metodologia proposta é discutida em detalhes, incluindo a descriçăo das etapas necessárias para a derivaçăo do procedimento de projeto para diferentes topologias de inversores de tensăo e o procedimento para obtençăo das curvas necessárias para o projeto. Finalizando, săo apresentados alguns exemplos de projeto para topologias de inversores monofásicos e trifásicos com saída a tręs fios e a quatro fios. Resultados experimentais săo apresentados para demonstrar a validade da metodologia de projeto proposta. Abstract in english This paper presents a systematized methodology of second-order output filter for inverters that synthesize sinusoidal voltage waveforms through digital pulse-width modulation (PWM). The objective of this methodology is to determine the largest corner frequency of the filter that ensure the specifica [...] tion of the maximum total harmonic distortion (THD) admissible in the output voltages of the PWM inverter, for linear and non-linear loads. The proposed methodology is discussed in detail, including the description of the required steps for the derivation of the design procedure for different topologies of voltage inverters and the procedure to obtain the design curve. Finally, it is presented some design examples for single-phase, three-phase three-wire and three-phase four-wire filters topologies. Experimental results have been provided to demonstrate the validity of the proposed design methodology.
Three-phase electric arc plasma torches
International Nuclear Information System (INIS)
Peculiarities of the electric arc plasma torches ac powering are considered in this article. Schematic and design of the three-phase 'Zvezda'-type plasma torch are described along with its characteristics. Method of the plasma torch calculation, based on similarity theory, is outlined. Analysis of ac arc magnetic rotation in the plasma torch is presented. Schematic and design of the three-phase EDP-type plasma torch are described along with its characteristics. The results of experimental investigation of electrode operating modes are presented. (author)
Optimizing three-phase planar transformer construction
Prieto López, Roberto; Asensi Orosa, Rafael; García Suárez, Oscar; Cobos Márquez, José Antonio; Flavio David, Gerez
2012-01-01
A three-phase transformer with flat conductor layers is proposed in this article. This arrangement is used for high current density transformers. Cost effectiveness in planar magnetic are related with the optimization in the number of layers in each winding. This fact takes more relevance for the medium and high power three-phase transformers where the number of parallels to achieve the required DCR is increased. The proposed method allows the use of off-the-shell core shapes that are used fo...
Sliding mode Control using 3D-SVM for Three-phase Four-Leg Shunt Active Filter
Directory of Open Access Journals (Sweden)
Bouzidi Mansour
2013-02-01
Full Text Available This paper proposes a sliding mode control strategy for a three-phase shunt active power filter. The SAPF consists of four-leg voltage source inverter bridge. The SAPF ensures full compensation for harmonic phase currents, harmonic neutral current, reactive power compensation and unbalanced nonlinear load currents. The modulation task can be carried out with three dimensional space vector modulation, which operate under a constant switching frequency. The simulation results show that the performance of the four-leg SAPF with the proposed control algorithm – compared with PI controller - is found considerably effective and adequate to compensate harmonics, reactive power, neutral current and balance load currents.
The overview of damping methods for three-phase grid-tied inverter with LLCL-filter
DEFF Research Database (Denmark)
Huang, Min; Blaabjerg, Frede
2014-01-01
Compared with LCL filter, an LLCL-filter is characterized with smaller size and lower cost for grid-connected inverters. But this high order filter may also have resonant problem which will affect the system stability. Many methods can be used to alleviate the resonant problem including active damping, passive damping or even without damping if it is designed conservative. In this paper, an overview of damping methods for three-phase voltage-source grid-tied with LLCL-filter is given. This paper also analyzes damping principle of each method including passive damping and active damping and shows the advantages as well as disadvantages of these methods.
Czech Academy of Sciences Publication Activity Database
Klíma, J.; Chomát, Miroslav; Schreier, Lud?k
Piscataway, NJ : IEEE Operations Center, 2002, s. 604-609. ISBN 0-7803-7657-9. [2002 IEEE International Conference on Industrial Technology - IEEE ICIT 02. Bangkok (TH), 11.12.2002-14.12.2002] R&D Projects: GA ?R GA102/01/0181 Keywords : analytical model * induction machine * voltage source inverter Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Harmonics mitigation of dead time effects in PWM converters using a repetitive controller
DEFF Research Database (Denmark)
Yang, Yongheng; Zhou, Keliang
2015-01-01
In order to prevent the power switching devices (e.g., the Insulated-Gate-Bipolar-Transistor, IGBT) from shoot-through in voltage source converter during a switching period, a dead time is added either in the hardware drivers of the IGBTs or implemented in the software Pulse-Width Modulation (PWM) scheme. Both methods will lead to a degradation of the injected current power quality. Thus, the harmonics induced by the dead time have to be compensated in order to achieve a satisfactory current as required by the standards. In this paper, a repetitive controller has been introduced to eliminate the dead-time effect in grid-connected PWM converters. The repetitive controller has been plugged into a proportional resonant based fundamental controller. Compared with the traditional dead-time compensation solutions, the repetitive controller can effectively compensate the dead-time harmonics as well as other low-order distortions, and also it is a simple method without hardware modifications. Experimental results aredemonstrating the advantages of the proposed dead-time effect mitigation method compared to the resonant based harmonic compensator.
Comparative Analysis of Three Topologies of Three-Phase Five Level Inverter
Directory of Open Access Journals (Sweden)
H. S. Sangolkar, P. A. Salodkar
2014-06-01
Full Text Available This paper presents the simulation and analysis of the three topologies of three phase 5-level inverter. We have considered the Flying Capacitor Multilevel Inverter (FCMLI, the Neutral Point Clamped or the Diode Clamped Multilevel Inverter (NPCMLI or DCMLI and the Cascaded H-Bridge Multilevel Inverter (H-bridge MLI. The comparison between these inverters is based on the %THD present in the output voltage. Each inverter is controlled by the multi-carrier sinusoidal pulse width modulation (SPWM. The analysis shows that the total harmonic distortion (THD is approximately 23% for DCMLI and 22% for PWM H-Bridge topologies, and it is about 24% for the FCMLI topology. The comparative results of the harmonic analysis have been obtained in MATLAB/SIMULINK.
A low cost rapid prototype platform for a three phase PFC rectifier application
DEFF Research Database (Denmark)
Haase, Frerk; Kouchaki, Alireza
In this paper the design and development of a low cost rapid prototype platform for a Three Phase PFC rectifier application is presented. The active rectifier consists of a SiC-MOSFET based PWM converter and a low cost rapid prototype platform for simulating and implementing the digital control algorithm. The digital controller is based on a for motor and power control widely used DSP/MCU platform from Texas Instruments. The design and simulation of the PFC controller is performed using the data flow driven graphical programming language MATLAB/SIMULINK. The actual programming of the processor is then performed using automatic code generation for embedded targets, which provided a close link between simulation and implementation of the PFC controller. The paper shows how this rapid prototype platform developed and how it was used for the design and implementation of the controller for a high efficient SiC based PFC application.
Directory of Open Access Journals (Sweden)
Chandra Babu Paduchuri
2014-01-01
Full Text Available This paper proposes the instantaneous p-q theory based fuzzy logic controller (FLC for multi converter unified power quality conditioner (MC-UPQC to mitigate power quality issues in two feeders three-phase four-wire distribution systems. The proposed system is extended system of the existing one feeder three-phase four-wire distribution system, which is operated with UPQC. This system is employed with three voltage source converters, which are connected commonly to two feeder distribution systems. The performance of this proposed system used to compensate voltage sag, neutral current mitigation and compensation of voltage and current harmonics under linear and nonlinear load conditions. The neutral current flowing in series transformers is zero in the implementation of the proposed system. The simulation performance analysis is carried out using MATLAB.
Directory of Open Access Journals (Sweden)
B. Santhosh Kumar
2014-02-01
Full Text Available This paper presents a novel structure for a three- phase four-wire (3P4W distribution system utilizing unified power quality conditioner (UPQC. The 3P4W system is realized from a three-phase three-wire system where the neutral of series transformer used in series part UPQC is considered as the fourth wire for the 3P4W system. A new control strategy to balance the unbalanced load currents is also presented in this paper. The neutral current that may flow toward transformer neutral point is compensated by using a four-leg voltage source inverter topology for shunt part. Thus, the series transformer neutral will be at virtual zero potential during all operating conditions. The simulation results based on MATLAB/Simulink are presented to show the effectiveness of the proposed UPQC-based 3P4W distribution system.
Three Phase to Three Phase Direct Matrix Converter using SPWM Technique
Sharon D. Ronald,; A. Sheela,; S. Josephin Mary,
2013-01-01
The principle of three phase SPWM AC-AC matrix converter using 9 bidirectional switching devices is explained. IGBT-power diode combination is used is main power switching device. Constant voltage and frequency sinusoidal supply voltage can be converted to variable voltage and frequency voltage using this converter. The working is described based on the working three phase to single phase matrix converter. MATLAB/ Simulink software is used for the simulation. The operation is analyzed for var...
The Investigation of Sinusoidal Single Phase Voltage Source Inverter Output Filter
Directory of Open Access Journals (Sweden)
Andrius Platakis
2011-08-01
Full Text Available The results of output filter investigation of single phase sine voltage source inverter (VSI are presented. The operating principle, construction and a most widely used topology of single phase voltage source inverter is discussed. The results obtained using modeling and experimental investigation are presented. The Total Harmonic Distortion of the inverter output voltage and maximal current of the output capacitor were analyzed using Matlab Simulink software. The 1 kW inverter prototype was built for experimental investigation. The inverter switches are realized using IGBT transistors. The toroidal iron powder core with distributed air gap was used as the core of the inductor. The experimental investigation of inductor core losses and maximal current of output filter capacitor were performed.Article in Lithuanian
Selective Harmonic Virtual Impedance for Voltage Source Inverters with LCL filter in Microgrids
Savaghebi, Mehdi; Vasquez, Juan Carlos; Jalilian, Alireza Jalilian; Guerrero, Josep M.; Lee, Tzung-lin
2012-01-01
This paper presents a new control approach for voltage source inverters ended with LCL filters for microgrid applications. The control approach consists of voltage and current inner control loops in order to fix the filter capacitor voltage and a virtual impedance loop. The virtual impedance is added in order to mitigate the voltage distortion after the output inductor and improve the load sharing among parallel inverters. A general case with a combined voltage harmonic and unbalance distorti...
Voltage Source Inverter/Converter for the Improvement of Power Quality Using Fuzzy Logic Controller
T Jagan Mohan Rao; Anil Kumar, P.
2014-01-01
In recent years, the applications of power electronics have grown tremendously. These power electronic systems offer highly nonlinear characteristics. To overcome those non linearities active power filters are preferred. This paper presents and compares the performance of two controllers namely Fuzzy Logic and Proportional Integral (PI) applied to a voltage source inverter / converter which operates as an active power filter. The active power filter is operated to compensate h...
Rodríguez Monter, Ana
2013-01-01
El trabajo desarrollado en esta Tesis se centra en optimizar el comportamiento de Voltage-Source Converters (VSCs) cuando son utilizados como interfaz con la red eléctrica, tanto para absorber como para entregar energía de la red con la mejor calidad posible y cumpliendo con los estándares. Para tal fin, esta Tesis se centra en el control de sistemas lineales conectados en cascada aplicados al control de VSCs conectados en paralelo con la red eléctrica a través de un filtro L, especialmente e...
Voltage Balancing of 4-level Capacitor-Clamped Voltage Source Inverter.
Czech Academy of Sciences Publication Activity Database
Kokeš, Petr; Semerád, Radko
Prague : Institute of Thermomechanics AS CR, v. v. i., 2008, s. 32-40. ISBN 978-80-87012-13-0. [Symposium Electric Machines and Drives, Power Electronics and Drive Control. Prague (CZ), 30.09.2008-02.10.2008] R&D Projects: GA MPO FT-TA4/077 Institutional research plan: CEZ:AV0Z20570509 Keywords : capacitor -clamped voltage source inverter * multilevel inverter * capacitor balancing Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Dynamic Modeling of UPFC by Two Shunt Voltage- Source Converters and a Series Capacitor
Directory of Open Access Journals (Sweden)
Farzad Mohammadzadeh Shahir
2013-10-01
Full Text Available The unified power flow controller (UPFC is one of the FACTS devices vastly applied in power systems. This paper presents the modeling of a new structure of UPFC consists of two shunt voltage-source converters and a series capacitor. Through the presented modeling, the transient and steady states responses of UPFC are well investigated. The results of the investigation are presented for the transient and steady states by simulating proposed system in MATLAB changing each system parameter.
Optimal Control of Input Rectifier in Voltage-Source Inverter Supplied from Unbalanced Power Grid.
Czech Academy of Sciences Publication Activity Database
Chomát, Miroslav; Schreier, Lud?k; Bendl, Ji?í
Montréal : IEEE, 2006, s. 1042-1045. ISBN 1-4244-0497-5. [International Symposium on Industrial Electronics 2006. Montreal (CA), 09.07.2006-13.07.2006] R&D Projects: GA ?R(CZ) GA102/06/0215 Institutional research plan: CEZ:AV0Z20570509 Keywords : unbalanced voltage supply * voltage-source inverter * pulse width modulation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Variable speed wind turbine generator system with current controlled voltage source inverter
International Nuclear Information System (INIS)
highlights: ? Current controlled voltage source inverter scheme for wind power application. ? Low voltage ride through of wind farm. ? Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.
PWM Switching Strategy for Torque Ripple Minimization in BLDC Motor
Salah, Wael A.; Ishak, Dahaman; Hammadi, Khaleel J.
2011-05-01
This paper describes a new PWM switching strategy to minimize the torque ripples in BLDC motor which is based on sensored rotor position control. The scheme has been implemented using a PIC microcontroller to generate a modified Pulse Width Modulation (PWM) signals for driving power inverter bridge. The modified PWM signals are successfully applied to the next up-coming phase current such that its current rise is slightly delayed during the commutation instant. Experimental results show that the current waveforms of the modified PWM are smoother than that in conventional PWM technique. Hence, the output torque exhibits lower ripple contents.
Conversor Boost PWM Entrelaçado com Comutaçăo Suave
Directory of Open Access Journals (Sweden)
Lúcio dos Reis Barbosa
2002-01-01
Full Text Available Este artigo apresenta uma topologia aprimorada de um conversor Boost PWM com comutaçăo suave. O circuito proposto, tendo duas chaves ativas entrelaçadas, opera com chaveamento suave, sob odulaçăo PWM (pulse-width-modulation. Além disso, este conversor fornece alta rendimento sob as condiçőes de operaçăo, para uma larga variaçăo de carga, e operando ŕ altas freqüęncias. Para ilustrar o princípio de operaçăo deste novo conversor apresenta-se um estudo pormenorizado, incluindo simulaçőes e resultados. A validade deste novo conversor é confirmada por meio dos resultados obtidos.
Three phase full wave dc motor decoder
Studer, P. A. (inventor)
1977-01-01
A three phase decoder for dc motors is disclosed which employs an extremely simple six transistor circuit to derive six properly phased output signals for fullwave operation of dc motors. Six decoding transistors are coupled at their base-emitter junctions across a resistor network arranged in a delta configuration. Each point of the delta configuration is coupled to one of three position sensors which sense the rotational position of the motor. A second embodiment of the invention is disclosed in which photo-optical isolators are used in place of the decoding transistors.
International Nuclear Information System (INIS)
Current sources are widely used in bio-impedance spectroscopy (BIS) measurement systems to maximize current injection for increased signal to noise while keeping within medical safety specifications. High-performance current sources based on the Howland current pump with optimized impedance converters are able to minimize stray capacitance of the cables and setup. This approach is limited at high frequencies primarily due to the deteriorated output impedance of the constant current source when situated in a real measurement system. For this reason, voltage sources have been suggested, but they require a current sensing resistor, and the SNR reduces at low impedance loads due to the lower current required to maintain constant voltage. In this paper, we compare the performance of a current source-based BIS and a voltage source-based BIS, which use common components. The current source BIS is based on a Howland current pump and generalized impedance converters to maintain a high output impedance of more than 1?M? at 2?MHz. The voltage source BIS is based on voltage division between an internal current sensing resistor (Rs) and an external sample. To maintain high SNR, Rs is varied so that the source voltage is divided more or less equally. In order to calibrate the systems, we measured the transfer function of the BIS systems with several known resistor and capacitor loads. From this we may estimate the resistance and capacitance of biological tissues using the least-squares method to minimize error between the measured transimpedance excluding the system transfer function and that from an impedance model. When tested on realistic loads including discrete resistors and capacitors, and saline and agar phantoms, the voltage source-based BIS system had a wider bandwidth of 10 Hz to 2.2 MHz with less than 1% deviation from the expected spectra compared to more than 10% with the current source. The voltage source also showed an SNR of at least 60 dB up to 2.2 MHz in comparison to the current source-based BIS system where the SNR drops below 40 dB for frequencies greater than 1 MHz. (paper)
Energy Technology Data Exchange (ETDEWEB)
Machado, Ricardo Q.; Pomilio, Jose A. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Eletrica e de Computacao], e-mail: ricardom@dsce.fee.unicamp.br; Buso, Simone [Universidade de Padova, Padua (Italy). Dept. de Engenharia da Informacao], e-mail: simone.buso@dei.unipd.it
2004-07-01
This paper describes a line-interactive single-phase to three-phase converter. The typical application is in rural areas supplied by the single-wire with earth return. The traditional objective of feeding a three-phase induction motor is not anymore the main concern for such conversion. Due to the evolution of the agro business, some of the local load (as electronic power converters, computers, communication equipment, etc.) requires high quality power, intended as sinusoidal, symmetrical and balanced three-phase voltage. Additionally, to maximize the power got from the feeder, the system provides a unitary power factor to the feeder. A three-phase PWM converter is used for this purpose. The power converter does not process all the load power, as in the conventional solutions, but only the fraction necessary to regulate the three-phase bus voltage. The control strategy, design highlights and experimental results are presented. (author)
Three Phase to Three Phase Direct Matrix Converter using SPWM Technique
Directory of Open Access Journals (Sweden)
Sharon D. Ronald,
2013-05-01
Full Text Available The principle of three phase SPWM AC-AC matrix converter using 9 bidirectional switching devices is explained. IGBT-power diode combination is used is main power switching device. Constant voltage and frequency sinusoidal supply voltage can be converted to variable voltage and frequency voltage using this converter. The working is described based on the working three phase to single phase matrix converter. MATLAB/ Simulink software is used for the simulation. The operation is analyzed for various modulation indexes and input voltages. The results are compared and the optimum condition for favorable operation is obtained.
Three-Phase Shunt Active Power Filter
Directory of Open Access Journals (Sweden)
Moleykutty George
2008-01-01
Full Text Available Active power filters have been widely used for harmonic elimination. The performance of a conventional three-phase shunt Active Power Filter (APF using Synchronous Detection Method (SDM has been compared with Nonlinear Autoregressive-Moving Average (NARMA-L2 based APF. The novelty of this study lies in the application of NARMA-L2 control to generate the amplitude of the reference supply current required by the APF circuit and the successful implementation of the APF system for harmonic elimination. The entire system has been modeled using MATLAB 6.1 toolbox. Simulation results demonstrate the applicability of NARMA-L2 controller for the control of APF.
Effect of Supply-Voltage Unbalanced on Voltage-Source Inverter.
Czech Academy of Sciences Publication Activity Database
Chomát, Miroslav; Schreier, Lud?k; Bendl, Ji?í
Dublin : The Institution of Engineering and Technology, Power Conversion and Applications, Profesional Network, 2006, s. 312-315. ISBN 0-86341-618-7. ISSN 0537-9989. [IET International Conference on Power Electronics, Machines and Drives (PEMD 2006) /3./. Dublin (IE), 04.04.2006-06.04.2006] R&D Projects: GA ?R(CZ) GA102/06/0215 Institutional research plan: CEZ:AV0Z20570509 Keywords : unbalanced voltage supply * voltage-source inverter * pulse width modulation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Stability analysis and design of the improved droop controller on a voltage source inverter
DEFF Research Database (Denmark)
Calabria, Mauro; Schumacher, Walter
2015-01-01
This paper studies the dynamics of a droop-controlled voltage source inverter connected to a stiff grid and addresses the use of the improved droop controller in order to enhance the dynamic behavior of the system. The small-signal stability of the inverter is studied in depth considering variations on its droop parameters, providing a general understanding on the functioning of such system. Finally, three methods to tune the dynamic droop gain are introduced and compared, providing analytical, simulation, and experimental results.
Directory of Open Access Journals (Sweden)
Javad Faiz
2011-01-01
Full Text Available A UPS inverter operates in wide load impedance ranges from resistive to capacitive or inductive load. At the same time, fast transient load response, good load regulation and good switching frequency suppression is required. The variation of the load impedance changes the filter transfer characteristic and thus the output voltage value. In this paper, an analysis and simulation of the single phase voltage source uninterruptible power supply (UPS with fourth order filter (multiple-filter in output inverter, based on the state space averaging and small signal linearization technique, is proposed. The simulation results show the high quality sinusoidal output voltage at different loads, with THD less than %5.
Marcelo Gradella Villalva; Marcos Fernando Espindola; Thais Gama de Siqueira; Ernesto Ruppert
2011-01-01
This paper describes the modeling and control of a three-phase grid-connected converter fed by a photovoltaic array. The converter is composed of an isolated DC-DC converter and a three-phase DC-AC voltage source inverter The converters are modeled in order to obtain small-signal transfer functions that are used in the design of three closed-loop controllers: for the output voltage of the PV array, the DC link voltage and the output currents. Simulated and experimental results are presented.E...
Evolutionary Computing Based Area Integration PWM Technique for Multilevel Inverters
S Jeevananthan
2007-01-01
The existing multilevel carrier-based pulse width modulation (PWM) strategies have no special provisions to offer quality output, besides lower order harmonics are introduced in the spectrum, especially at low switching frequencies. This paper proposes a novel multilevel PWM strategy to corner the advantages of low frequency switching and reduced total harmonic distortion (THD). The basic idea of the proposed area integration PWM (AIPWM) method is that the area of the required sinusoidal (fun...
Llopis, Francisco
2013-01-01
The circuit presented in this paper aims at providing three 40 Vpp 50Hz AC voltages sources with 120-degree phase separation between them. This is a fully analogue circuit that uses standard, low-cost electronic components without resorting to a microcontroller as previously proposed by Shirvasar et al [1]. This circuit may serve as a basis for a low-voltage 3P-AC power supply that students may safely use to realize experiments, i.e. about the principles and applications of three-phase AC power lines, without the risk of electric shocks.
Directory of Open Access Journals (Sweden)
P.Narasimhulu
2014-09-01
Full Text Available A reduced rating voltage-source converter with a zig-zag transformer as a distribution static compensator is proposed for power-quality improvement in the three-phase four-wire distribution system. The source voltages in the distribution systems are also experiencing power quality problems, such as harmonics, unbalance, flicker, sag, swell, etc. The distribution static compensator (DSTATCOM is proposed for compensating power quality problems in the current, and the dynamic voltage restorer (DVR is used for mitigating the power quality problems in the voltage. The zig-zag transformer is used for the neutral current compensation. Distribution systems are facing severe power-quality (PQ problems, such as poor voltage regulation, high reactive power and harmonics current burden, load unbalancing, excessive neutral current, etc. The zig-zag transformer is used for providing a path to the zero-sequence current. The DSTATCOM is used to improve the quality of power to the non linear loads. By using both zig-zag transformer and DSTATCOM in the distribution system the rating of the voltage source converter can be reduced. Hence it can be also called reduced rating device. The performance of the DSTATCOM is validated through extensive simulations using MATLAB software with its Simulink and power system block set toolboxes.
A Three-Phase Dual-Input Matrix Converter for Grid Integration of Two AC Type Energy Resources
DEFF Research Database (Denmark)
Liu, Xiong; Wang, Peng
2013-01-01
This paper proposes a novel dual-input matrix converter (DIMC) to integrate two three-phase ac type energy resources to a power grid. The proposed matrix converter is developed based on the traditional indirect matrix converter under reverse power flow operation mode, but with its six-switch voltage source converter replaced by a nine-switch configuration. With the additional three switches, the proposed DIMC can provide six in put terminals, which make it possible to integrate two independent ac sources into a single grid-tied power electronics interface. The proposed converter has input-to-output voltage boost capability since power flows from the converter’s voltage source side to its current source side. Commanded currents can be extracted from the two input sources to the grid. The proposed control and modulation schemes guarantee sinusoidal input and output waveforms as well as unity input power factors. The simulation and experimental results using a laboratory prototype are provided to validate the effectiveness of the proposed control and modulation schemes for the proposed converter.
Directory of Open Access Journals (Sweden)
BOTEZAN, A.
2015-08-01
Full Text Available The paper presents the hysteresis current control of the voltage source inverter. The eMEGAsim real-time simulator is developed by OPAL-RT. Real-time simulation is used in many cases because it allows the behavior of the industrial processes operation to be determined. Two research directions are developed in this case, Rapid Control Prototyping and Hardware-In-the-Loop. Using eMEGAsim simulator allows implementing the command and control strategy of a single-phase voltage source inverter. At this stage, the real-time behavior of operation is monitored, because the voltage source inverter will be the part of a single-phase shunt active filter. In order to command and control the voltage source inverter, the current and voltage signals are acquired, since these signals are necessary to estimate reference signal. Extension of the Instantaneous Reactive Power Theorem is used because this theorem is suitable for single-phase active filter control. To test the real-time command and control strategy implemented, it was used a low power single-phase voltage source inverter (full bridge.
Digital Computer Transient Models of Three-Phase Inverter Systems Under Normal and Fault Conditions
Gawish, Said Abdelhamid Atiya
In many industrial applications, variable speed drives of electrical machines are needed. This speed control can be met either by dc or ac machines. The ac machines have several distinct advantages compared to dc machines due to the absence of commutators, therefore, a variable -voltage, variable-frequency power supply is normally required for speed control of ac machines. This power supply can be obtained by a dc link converter system that consists of a rectifier and inverter. In this dissertation the waveforms and transient response of a three-phase forced-commutated inverters are simulated on a digital computer from basic circuit theory. Both the voltage source inverter (VSI) and the current source inverter (CSI) are simulated using thyristors with real characteristics. The simulation is further modified to give three-phase currents with adjustable frequency to be used in adjustable speed induction motor drives or the starting of synchronous motors from rest. The digital simulation of Gate Turn-Off (GTO) thyristor inverters feeding an induction motor is presented and can allow for step frequency change for the study of adjustable speed induction motor drives. A naturally-commutated three-phase inverter using thyristors with real characteristics was also simulated to study VSIs and CSIs. The interactions between the load parameters and the inverter circuit parameters are investigated. The parameters studied include ratio of dc voltage to amplitude of ac voltage, ratio of smoothing inductance to load inductance and triggering angle (alpha). Since the naturally-commutated CSI system is widely used in power applications, it was investigated under different types of fault s occurring both on the line and in the inverter circuit. These faults include three-phase short circuits, thyristor failures, line-to-line faults, false triggering and open circuits. A digital computer was used to simulate these faults and the system response because it is difficult to obtain the information herein for abnormal operations by any other method. This study clearly demonstrates that the theoretical circuit so simulated for different types of faults will allow designers of systems to predict accurately values of, short-circuit current ratios, maximum fault clearing times, limiting values of commutating capacitors and transient recovery voltage excursions. (Abstract shortened with permission of author.).
Directory of Open Access Journals (Sweden)
SAFDAR FASAL T K, UNNIKRISHNAN L
2013-07-01
Full Text Available This paper presents a performance study of the proportionalintegral controller andthe fuzzy logic controller in scalar speed control of three phase squirrel cage induction motor drive. Here the speed control is possible by varying supply frequencyusing a voltage source inverter while keeping voltage to frequency ratio as a constant. Speed error is given as inputto the proportional integral controller, and speed error and change in speed error are given as input to the fuzzy logic controller.The controller output controls the reference of sinusoidal pulse width modulation. Hence, the fundamental frequency and fundamental voltage of inverter output can be varied to control the motor speed.The performance of proportional integral controller and fuzzy logic controller underload torqueand reference speed variationisevaluated by simulation results in Simulink.
Estimation of the Plant Time Constant of Current-Controlled Voltage Source Converters
DEFF Research Database (Denmark)
Vidal, Ana; Yepes, Alejandro G.
2014-01-01
Precise knowledge of the plant time constant is essential to perform a thorough analysis of the current control loop in voltage source converters (VSCs). As the loop behavior can be significantly influenced by the VSC working conditions, the effects associated to converter losses should be included in the model, through an equivalent series resistance. In a recent work, an algorithm to identify this parameter was developed, considering the inductance value as known and practically constant. Nevertheless, the plant inductance can also present important uncertainties with respect to the inductance of the VSC interface filter measured at rated conditions. This paper extends that method so that both parameters of the plant time constant (resistance and inductance) are estimated. Such enhancement is achieved through the evaluation of the closed-loop transient responses of both axes of the synchronous reference frame when a proportional integral current controller is implemented. Experimental results validate the approach.
Selective Harmonic Virtual Impedance for Voltage Source Inverters with LCL filter in Microgrids
DEFF Research Database (Denmark)
Savaghebi, Mehdi; Vasquez, Juan Carlos
2012-01-01
This paper presents a new control approach for voltage source inverters ended with LCL filters for microgrid applications. The control approach consists of voltage and current inner control loops in order to fix the filter capacitor voltage and a virtual impedance loop. The virtual impedance is added in order to mitigate the voltage distortion after the output inductor and improve the load sharing among parallel inverters. A general case with a combined voltage harmonic and unbalance distortion is considered. In such a case, voltage distortion is mitigated by inserting capacitive virtual impedance for negative sequence of fundamental component as well as positive and negative sequences of main harmonic components. Furthermore, resistive virtual impedances are added at these components in order to provide a proper load sharing and make the overall system more damped. Simulation results are presented to demonstrate the effectiveness of the proposed control approach.
MODELING AND SIMULATION OF A NOVEL SERIES/PARALLEL VOLTAGE SOURCES MULTILEVEL INVERTER
Directory of Open Access Journals (Sweden)
N.SANTHOSH SINGH.B,
2011-06-01
Full Text Available In this paper, a new topology of cascaded multilevel inverter with a high number of steps associated with a low number of switches is presented. A multilevel voltage is obtained by cascading two H-bridges and an inverter. Voltage sources are connected in series/parallel by the switching devices. The size, complexity and power consumption in the gate driving circuits is also reduced. Reduction of rating of the switches is another advantage. The total harmonic distortion (THD is reduced with more number of steps in output voltage without using pulse width modulation techniques. The proposed setup configures theoretical approach along with simulations carried on MATLAB/SIMULINK environment. Simulation results are shown and compared with theoretical results.
Directory of Open Access Journals (Sweden)
Tian Yizhi
2013-01-01
Full Text Available Nowadays, there are several renewable power sources connected into power grid with full power Voltage Source Inverter (VSI, such as photovoltaic power system and variable speed wind turbines. The operation state variables of full power VSI should be adjusted seamlessly in order to reduce the fluctuation of output power. The current linearization control strategy leads a certain extent impact component during the dynamic motion process. This study present the Brochistos Chronos Control Strategy (BCCS based on Hamilton theory, with the flexibility of full power VSI system, the smoothness and promptness is reflected in integrated process by the way of regulates state variables precisely. The effectiveness of this control strategy is be verified by the simulation results and the overall process fulfill the requirements of the duration as short as possible.
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede
2015-01-01
Active damping and harmonic compensation are two common challenges faced by LCL-filtered voltage source converters. To manage them holistically, this paper begins by proposing a virtual RC damper in parallel with the passive filter capacitor. The virtual damper is actively inserted by feeding back the passive capacitor current through a high-pass filter, which indirectly, furnishes two superior features. They are the mitigation of phase lag experienced by a conventional damper and the avoidance of instability caused by the negative resistance inserted unintentionally. Moreover, with the virtual RC damper, the frequency region, within which the harmonic compensation is effective, can be extended beyond the gain crossover frequency. This is of interest to some high-performance applications, but has presently not been achieved by existing schemes. Performance of the proposed scheme has been tested in the laboratory with results obtained for demonstrating stability and harmonic compensation.
FPGA techniques based new hybrid modulation strategies for voltage source inverters.
Sudha, L U; Baskaran, J; Elankurisil, S A
2015-01-01
This paper corroborates three different hybrid modulation strategies suitable for single-phase voltage source inverter. The proposed method is formulated using fundamental switching and carrier based pulse width modulation methods. The main tale of this proposed method is to optimize a specific performance criterion, such as minimization of the total harmonic distortion (THD), lower order harmonics, switching losses, and heat losses. The proposed method is articulated using fundamental switching and carrier based pulse width modulation methods. Thus, the harmonic pollution in the power system will be reduced and the power quality will be augmented with better harmonic profile for a target fundamental output voltage. The proposed modulation strategies are simulated in MATLAB r2010a and implemented in a Xilinx spartan 3E-500 FG 320 FPGA processor. The feasibility of these modulation strategies is authenticated through simulation and experimental results. PMID:25821852
An Impedance-Based Stability Analysis Method for Paralleled Voltage Source Converters
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede
2014-01-01
This paper analyses the stability of paralleled voltage source converters in AC distributed power systems. An impedance-based stability analysis method is presented based on the Nyquist criterion for multiloop system. Instead of deriving the impedance ratio as usual, the system stability is assessed based on a series of Nyquist diagrams drawn for the terminal impedance of each converter. Thus, the effect of the right half-plane zeros of terminal impedances in the derivation of impedance ratio for paralleled source-source converters is avoided. The interaction between the terminal impedance of converter and the passive network can also be predicted by the Nyquist diagrams. This method is applied to evaluate the current and voltage controller interactions of converters in both grid-connected and islanded operations. Simulations and experimental results verify the effectiveness of theoretical analysis.
Virtual-Impedance-Based Control for Voltage-Source and Current-Source Converters
DEFF Research Database (Denmark)
Wang, Xiongfei; Li, YunWei
2015-01-01
The virtual impedance concept is increasingly used for the control of power electronic systems. Generally, the virtual impedance loop can either be embedded as an additional degree of freedom for active stabilization and disturbance rejection, or be employed as a command reference generator for the converters to provide ancillary services. This paper presents an overview of the virtual-impedance-based control strategies for voltage-source and current-source converters. The control output impedance shaping attained by the virtual impedances is generalized first using the impedance-based models. Different virtual impedances and their implementation issues are then discussed. A number of practical examples are demonstrated to illustrate the feasibility of virtual impedances. Emerging applications and future trends of virtual impedances in power electronic systems conclude this paper.
Directory of Open Access Journals (Sweden)
Bogimi Sirisha
2012-03-01
Full Text Available In this paper, a three-phase two leg neutral point clamped (NPC converter is presented for power factor correction and dc-link voltage regulation. The adopted converter has simpler circuit configuration and less number of power switches compared to three-level PWM converter. In this circuit configuration, only eight power switches and four clamping diodes with voltage stress of half the dc bus voltage are used. A simplified space vector pulse width modulation scheme (SVPWM is also adopted to track the line current commands. A reference voltage vector is generated on the ac terminal for drawing the sinusoidal line currents with unity power factor. This algorithm reduces the time required to calculate the switching time durations of voltage vectors. The simulation results have been presented to verify the validity and effectiveness of the proposed control strategy.
System For Characterizing Three-Phase Brushless dc Motors
Howard, David E.; Smith, Dennis A.
1996-01-01
System of electronic hardware and software developed to automate measurements and calculations needed to characterize electromechanical performances of three-phase brushless dc motors, associated shaft-angle sensors needed for commutation, and associated brushless tachometers. System quickly takes measurements on all three phases of motor, tachometer, and shaft-angle sensor simultaneously and processes measurements into performance data. Also useful in development and testing of motors with not only three phases but also two, four, or more phases.
Quark-hadron three-phase mixture of baryonic matter
International Nuclear Information System (INIS)
The phase diagrams of strongly interacting baryonic matter are constructed in a phenomenological model assuming three phases: Hadrons, quark-gluon plasma and constituent quarks. Three-phase mixture states are considered in detail and it is shown that these states cover a finite area in the energy density-baryonic density plane. Possible hydrodynamic expansion processes involving the three-phase coexistence region in relativistic heavy-ion collisions are outlined. (orig.)
Scientific Electronic Library Online (English)
Ricardo Q., Machado; Amílcar F. Q., Gonçalves; Simone, Buso; José A., Pomilio.
2009-09-01
Full Text Available Este artigo propőe uma soluçăo para a conexăo direta de geradores de induçăo trifásicos em uma rede monofásica com regulaçăo de vazăo o que faz com que, a velocidade do gerador de induçăo se mantenha acima de sua velocidade síncrona. Para que a conexăo entre gerador e rede monofásica seja satisfatór [...] ia e para que os critérios de qualidade de energia sejam preservados, o controle do fluxo de energia, entre a rede monofásica e o conversor PWM trifásico, é realizado empregando a idéia de sistema interligado ajustando a defasagem e amplitude da tensăo sintetizada pelo conversor em relaçăo a tensăo da rede monofásica de forma que o fator de potęncia na rede monofásica seja unitário. Em relaçăo ao conversor de potęncia, espera-se que o mesmo produza tensőes senoidais, com freqüęncia e amplitude fixas para que o gerador de induçăo opere balanceado. O artigo descreve a estratégia de controle do inversor, o critério de projeto dos controladores e apresenta alguns resultados experimentais. Abstract in english This paper proposes a solution for the direct connection of a three-phase induction generator to a single-phase feeder. This high power quality system is intended to be used in micro-hydro power plants applications with control of the water flow. It is employed to maintain the speed of the induction [...] generator greater than its synchronous value. The difference between the generated power and the power consumed by the local load flows through the single-phase feeder. The power flow control is provided by a three-phase PWM inverter that additionally guarantees the local power quality. A system with good power quality must have sinusoidal and constant amplitude voltages, fixed frequency operation, balanced induction generator voltages and currents, harmonics and reactive power compensation. The paper describes the inverter control strategy, presents design criteria of the controllers, and shows experimental results.
An improved fault-tolerant control scheme for PWM inverter-fed induction motor-based EVs.
Tabbache, Bekheďra; Benbouzid, Mohamed; Kheloui, Abdelaziz; Bourgeot, Jean-Matthieu; Mamoune, Abdeslam
2013-11-01
This paper proposes an improved fault-tolerant control scheme for PWM inverter-fed induction motor-based electric vehicles. The proposed strategy deals with power switch (IGBTs) failures mitigation within a reconfigurable induction motor control. To increase the vehicle powertrain reliability regarding IGBT open-circuit failures, 4-wire and 4-leg PWM inverter topologies are investigated and their performances discussed in a vehicle context. The proposed fault-tolerant topologies require only minimum hardware modifications to the conventional off-the-shelf six-switch three-phase drive, mitigating the IGBTs failures by specific inverter control. Indeed, the two topologies exploit the induction motor neutral accessibility for fault-tolerant purposes. The 4-wire topology uses then classical hysteresis controllers to account for the IGBT failures. The 4-leg topology, meanwhile, uses a specific 3D space vector PWM to handle vehicle requirements in terms of size (DC bus capacitors) and cost (IGBTs number). Experiments on an induction motor drive and simulations on an electric vehicle are carried-out using a European urban driving cycle to show that the proposed fault-tolerant control approach is effective and provides a simple configuration with high performance in terms of speed and torque responses. PMID:23916869
A New Topology of Three-Phase Four-Wire UPQC with a Simplified Control Algorithm
Directory of Open Access Journals (Sweden)
Yash Pal
2012-03-01
Full Text Available In this paper, a simplified control algorithm based on unit vector template generation (UVTG is proposed for a star-delta supported three-phase four-wire (3P-4W unified power quality conditioner (UPQC topology for the improvement of different power quality problems. Different topologies reported in literature for 3P-4W UPQC use active compensation for the mitigation of source neutral current along with other power quality (PQ problems, while the uses of passive elements for the mitigation of source neutral current are advantageous over the active compensation due to ruggedness and less complexity of control. Hence, in this paper a star-delta transformer is connected in shunt near the load for mitigation of source neutral current, while three-leg voltage source inverters (VSIs based shunt and series active power filters (APFs of 3P-4W UPQC mitigate the current and voltage based distortions, respectively. A simple control algorithm based on Unit Vector Template Generation (UVTG is used as a control strategy of UPQC for mitigation of different PQ problems. In this control scheme, the current/voltage control is applied over the fundamental supply currents/load voltages instead of fast changing APFs currents/voltages, thereby reducing the effects of computational delay and the required sensors. The performance of the proposed topology of UPQC is analyzed through simulations results using MATLAB software with its Simulink and Power System Block set toolboxes.
Push-Pull Converter Fed Three-Phase Inverter for Residential and Motor Load
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Samuel Rajesh Babu
2015-06-01
Full Text Available The proposed paper is an new approach for power conditioning of a PV (photo-voltaic cell array. The main objective is to investigate an approach to provide and improve the delivered electric energy by means of power conditioning structures with the use of alternative renewable resources (ARRs for remote rural residential or industrial non-linear loads. This approach employs a series-combined connected boost and buck boost DC-DC converter for power conditioning of the dc voltage provided by a photo-voltaic array. The input voltage to the combined converters is 100 V provided from two series connected PV cells, which is converted and increased to 200 V at the dc output voltage. Series-combined connected boost and buck-boost DC-DC converters operate alternatively. This helps to reduce the input ripple current and provide the required 400 Vdc on a sinusoidal PWM three-phase inverter. Analysis of the two series-combined DC-DC converters is presented along with simulation results. Simulations of the series-combined DC-DC converters are presented with an output DC voltage of 200 V and a maximum output load of Po = 600 W.
PERFORMANCE ANALYSIS OF SENSORLESS BLDC MOTOR DRIVE SYSTEM USING ASYMMETRIC PWM CONTROL TECHNIQUE
Directory of Open Access Journals (Sweden)
R.Meenakshi
2012-05-01
Full Text Available This paper describes the simulation model for four-switch three-phase (FSTP brushless dc (BLDC motor drives using novel voltage PWM technique. In this paper a back EMF based sensor less scheme is clearly explained with the help of MATLABSIMULINK models. The low cost BLDC driver is achieved by the reduction of switch device count, cost down of control, and saving of hall sensors for commercial applications. Field programmable gate array was chosen as the hardware platform because of its benefits like high operating frequency and parallel processing capabilities. Asymmetric pulse width modulation scheme is developed to drive FSTP BLDC motors with the desired dynamic and static speed–torque characteristics. The simulation analysis of the back EMF based sensor less BLDC driver will be discussed and the performance using novel schemes will be evaluated.
Self oscillating PWM modulators, a topological comparison
DEFF Research Database (Denmark)
Poulsen, SŘren; Andersen, Michael Andreas E.
2004-01-01
High precision control of the output voltage or current of a switch mode converter with fast response is required for a number of applications. Dependent on the type of application, the desired precision and transient response can be difficult, if not impossible, to achieve with standard PWM control caused by limitations in dynamic capabilities which often limits fast tracking of a reference signal, or fast settling during load steps due to too small achievable control loop bandwidth. Achievable open loop bandwidth for standard voltage and current mode PWM modulators is typical in the fs/10 or fs/đ range respectively, where fs is the switching frequency of the converter. For some applications this will require unacceptable high switching frequency to achieve enough control loop bandwidth for the desired dynamic performance. With self oscillating modulators, the open loop bandwidth is equal to fs which makes this type of modulators an excellent choice for a wide range of applications. Self oscillating PWM modulators can be made in a number of ways, either as voltage or current mode modulators, and the self oscillating behavior can be achieved either by using hysteresis control or by shaping the open loop function of the modulator so its gain and phase response causes a closed loop natural oscillation. The two main types of self oscillating modulators have many similarities, but differences in dynamic performance and linearity are present. The work presented is related to the author's work with switch mode audio power amplifiers, where linear tracking of the reference signal is of major importance. Use of the modulator topologies presented are not limited to this kind of equipment, but can be used in a very wide range of applications from very low to very high power levels.
Single-Phase Optimal Odd PWM Problem.
Czech Academy of Sciences Publication Activity Database
Kujan, Petr; Hrom?ík, M.; Šebek, M.
Piscataway : IEEE, 2008, s. 371-378. ISBN 978-1-4244-1767-4; ISBN 978-1-4244-1766-7. [The 34th Annual Conference of the IEEEE Industrial Electronics Society. Orlando (US), 10.12.2008-13.12.2008] R&D Projects: GA MŠk(CZ) 1M0567; GA ?R(CZ) GA102/08/0186 Grant ostatní: GA MŠk(CZ) LA300 Institutional research plan: CEZ:AV0Z10750506 Keywords : Optimal PWM problem * selected harmonics elimination * Newton identities Subject RIV: BC - Control Systems Theory
Three phase power conversion system for utility interconnected PV applications
Porter, David G.
1999-03-01
Omnion Power Engineering Corporation has developed a new three phase inverter that improves the cost, reliability, and performance of three phase utility interconnected photovoltaic inverters. The inverter uses a new, high manufacturing volume IGBT bridge that has better thermal performance than previous designs. A custom easily manufactured enclosure was designed. Controls were simplified to increase reliability while maintaining important user features.
Teruya, Daisuke; Masukawa, Shigeo; Iida, Shoji
We propose a novel inverter that can be operated either as a Current Source Inverter (CSI) or as a Voltage Source Inverter (VSI) by changing only the control signals. It is proper to apply it to the interconnecting system with renewal energy, such as photovoltaic cells or wind generation systems, to a grid. This inverter is usually operated as the CSI connected to the grid. Even if the energy source has a lower voltage than the grid, the energy can be supplied to the grid through the proposed inverter. The power factor can be briefly maintained at almost unity. When power supply from the grid is interrupted, the proposed circuit should be operated as the VSI in the stand-alone operation mode. In this way, the circuit can maintain a constant output voltage to the loads. In this paper, the proposed circuit configuration and the control schemes for both the CSI and the VSI are described. Further, the circuit characteristics for both are discussed experimentally.
Characteristics and application of three-phase extraction systems
International Nuclear Information System (INIS)
A literature review dealing with three-phase extraction systems has been given. A classification of three-phase systems and their physicochemical characteristics have been presented. Mechanisms and reasons of the liquid third phase separation have been discussed. Studies on the partition of elements (V, Cd, REE and others) and organic compounds between three equilibrated phases in extraction systems of various types have been presented. Literature data concerning the application of three-phase extraction systems to separation, isolation and concentration of elements prior to their determination by various methods have been reviewed. 181 refs., 5 tabs
Design and Implementation of Three Phase Unbalanced Voltage Motor Controller
Directory of Open Access Journals (Sweden)
M. A. A. Mashud
2013-09-01
Full Text Available A state-of-the-art-technology was used to design the unbalanced three phase motor controller. The fluctuation of line voltage has been questioned in recent times due to the use of heavy powered machine with three phases. This paper is focused on deriving a control scheme to drive a three phase motor that could be used in industry or households. The very simple circuitry has been employed in this design. To do this, extensive MATLAB analysis and PSpice software was conducted in order to optimize the control system and finally the results are practically verified.
Numerical Iterative Methods Solving three-phase Multilevel Voltage Converter.
Czech Academy of Sciences Publication Activity Database
Kujan, Petr
Vol. IEEE CACSC CFP10CAC-CDR. Yokohama : IEEE, 2010, s. 1801-1806. ISBN 978-1-4244-5355-9. [The 10th IEEE International Symposium on Computer-Aided Control System Design. Yokohama, Kanagawa (JP), 08.09.2010-10.09.2010] R&D Projects: GA MŠk(CZ) 1M0567 Grant ostatní: GA ?R(CZ) GPP103/10/P323 Institutional research plan: CEZ:AV0Z10750506 Keywords : multilevel converter * numerical methods * optimal PWM * selective harmonic elimination Subject RIV: BC - Control Systems Theory
Intelligent Positioning Fuzzy Servomechanism Under PWM Nonlinear Loads
Scientific Electronic Library Online (English)
D., Rangel; A. L., Rivera; P.D., Alaníz; R., Castańeda; V.M., Castańo.
2010-04-01
Full Text Available Se desarrolla un servomecanismo difuso de posicionamiento angular inteligente experimental perturbado por cargas no-lineales basadas en transitorios mecánicos generados mediante la modulación de ancho de pulso (PWM). El sistema de posicionamiento difuso desarrollado es capaz de alcanzar la posición [...] angular con gran precisión aún cuando la respuesta es afectada por la aplicación de distintas cargas PWM no lineales. Abstract in english An experimental intelligent angular positioning fuzzy servomechanism excited by a nonlinear load based on a mechanical transient Pulse Width Modulation (PWM) is developed. This fuzzy positioning system is capable of reaching the angular position with high precision even when the response is affected [...] by the application of different PWM nonlinear loads.
Evolutionary Computing Based Area Integration PWM Technique for Multilevel Inverters
Directory of Open Access Journals (Sweden)
S. Jeevananthan
2007-06-01
Full Text Available The existing multilevel carrier-based pulse width modulation (PWM strategies have no special provisions to offer quality output, besides lower order harmonics are introduced in the spectrum, especially at low switching frequencies. This paper proposes a novel multilevel PWM strategy to corner the advantages of low frequency switching and reduced total harmonic distortion (THD. The basic idea of the proposed area integration PWM (AIPWM method is that the area of the required sinusoidal (fundamental output and the total area of the output pulses are made equal. An attempt is made to incorporate two soft computing techniques namely evolutionary programming (EP and genetic algorithm (GA in the generation and placement of switching pulses. The results of a prototype seven-level cascaded inverter experimented with the novel PWM strategies are presented.
An Improved Switching Period Optimization Space Vector PWM Strategy
Guoqiang Chen; Jianli Kang; Junwei Zhao
2014-01-01
In order to improve the performance of space vector PWM (pulse width modulation), the optimization is widely used. The switching period optimization space vector PWM can reduce both total harmonic distortion and spectrum peaks, so it has important application prospects and has been widely discussed among several types of optimization strategies. Aiming at the characteristic of uncontrollable switching frequency, the study proposes an improved optimization method ...
A Composite PWM Control Strategy for Boost Converter
Qingfeng, Liu; Zhaoxia, Leng; Jinkun, Sun; Huamin, Wang
In order to improve the control performance of boost converter with large signal disturbance, a composite PWM control strategy for boost converter operating in continuous condition mode (CCM) was proposed in this paper. The parasitical loss of Boost converter was analyzed and a loss compensation strategy was adopted to design feed-forward tracker for converter. The composite PWM controller consisted of the tracker and PID controller. Simulation and experiment results validated the validity of the control strategy presented in this paper.
A high-quality multi-level voltage source inverter suitable for high power/high voltage applications
International Nuclear Information System (INIS)
In this paper new magnitudes for D C side capacitors' voltages of a multi level voltage source inv enter are presented. Using these magnitudes of D C side capacitors voltage allow generation of ?3k steps of A C output voltage by cascade connection of only N single-phase full bridge inverter. This subject has resulted in almost sinusoidal output voltage wave form. Approximated equal area pulse amplitude modulation technique is used to calculate the duration of each step of voltage, which has resulted in reduction of complexity of control circuit. A simple closed-loop controller is developed for controlling the voltage of D C side capacitors. Harmonic analysis and capacitor calculations are presented, too. Simulation results have been used to verify the overall operation of the proposed multi level voltage source inverter in feeding a R-L load with a stepped sinusoidal wave form
Vormedal, Pĺl Kristian Myhrer
2010-01-01
This master thesis has investigated the possible application of voltage source converters (VSC) for the interconnection of offshore installations, i.e. wind farms and petroleum platforms, in a multiterminal DC (MTDC) grid. The master thesis is written at the Norwegian University of Science and Technology, Department of Electric Power Engineering and is a continuation of the project written during the autumn of 2009. The work has been carried out in cooperation with Statnett SF, the Norwegian ...
Modeling Hysteresis Effect in Three-Phase Relative Permeability
Kianinejad, A.; Chen, X.; DiCarlo, D. A.
2014-12-01
Simulation and fluid flow prediction of many petroleum enhanced oil recovery methods as well as environmental processes such as carbon dioxide (CO2) geological storage requires accurate modeling and determination of relative permeability under different saturation histories. Based on this critical need, there has been several different three-phase relative permeability models developed to predict the hysteresis effects in relative permeability, most of which requiring many different parameters which introduce extreme complexity to the models for practical purposes. In this work, we experimentally measured three-phase, water/oil/gas, relative permeability in a 1-m long water-wet sand pack, under several different flow histories. We measured the in-situ saturations along the sand pack using a CT scanner. We then determined the relative permeabilities directly from the measured in-situ saturations, using unsteady-state method. Based on our results, good estimation of residual saturations yields in excellent three-phase relative permeability estimations by just using the simple, standard relative permeability models such as, Saturation Weighted Interpolation (SWI), Corey's and Stones. Our results show that, the key parameter to model the hysteresis in three-phase relative permeability (effect of saturation history) is the residual saturations. Once the residual saturations were correctly determined for each specific saturation path, the standard relative permeability models can predict the three-phase relative permeabilities perfectly.
Harmonic three-phase circular inclusions in finite elasticity
Wang, Xu; Schiavone, Peter
2015-09-01
We study the exterior stress field in a three-phase circular inclusion which is bonded to the surrounding matrix through an intermediate interphase layer. All three phases belong to a particular class of compressible hyperelastic materials of harmonic type. We focus on the design of a harmonic elastic inclusion which by definition, does not disturb the sum of the normal stresses in the surrounding matrix. We show that in order to make the coated inclusion harmonic, certain inequalities concerning the material and geometric parameters of the three-phase composite must first be satisfied. The corresponding remote loading parameters can then be uniquely determined while keeping the associated phase angles arbitrary. Our results allow for both uniform and non-uniform remote loading. We show that the stress field inside the inclusion is uniform when the remote loading is uniform.
EMC Increasing of PWM Rectifier in Comparison with Classical Rectifier
Directory of Open Access Journals (Sweden)
R. Dolecek
2008-12-01
Full Text Available Pulse width modulated rectifier is a very popular topic nowadays. The modern industrial production demands continuous and lossless conversion of electrical energy parameters. This need leads to wide spread of power semiconductor converters. The rapid development in power electronics and microprocessor technology enables to apply sophisticated control methods that eliminate negative side effects of the power converters on the supply network. The phase controlled thyristor rectifiers overload the supply network with higher harmonics and reactive power consumption. That is why the PWM rectifier is being examined. In comparison with the phase controlled rectifier it can be controlled to consume nearly sinusoidal current with power factor equal to unity. Another advantage is its capability of energy recuperation. The PWM rectifier can assert itself for its good behavior in many applications, for example as an input rectifier in indirect frequency converter, or in traction. Traction vehicles equipped with PWM rectifier do not consume reactive power, do not load the supply network with higher harmonics, and the recuperation is possible. The paper deals with the PWM rectifier functional model realization and examination. Electromagnetic compatibility of PWM rectifier and classical phase controlled rectifier is compared on the basis of the input current harmonic analysis.
Periodic Operation of Three-Phase Catalytic Reactors.
Czech Academy of Sciences Publication Activity Database
Silveston, P.T.; Hanika, Ji?í
2005-01-01
Ro?. 82, ?. 6 (2005), s. 1105-1142. ISSN 0008-4034 Institutional research plan: CEZ:AV0Z4072921 Keywords : three-phase reactors * trickle bed * periodic operation Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.574, year: 2005
Three-phase flow? Consider helical-coil heat exchangers
Energy Technology Data Exchange (ETDEWEB)
Haraburda, S.S. [Bayer Corp., New Martinsville, WV (United States)
1995-07-01
In recent years, chemical process plants are increasingly encountering processes that require heat exchange in three-phase fluids. A typical application, for example, is heating liquids containing solid catalyst particles and non-condensable gases. Heat exchangers designed for three-phase flow generally have tubes with large diameters (typically greater than two inches), because solids can build-up inside the tube and lead to plugging. At the same time, in order to keep heat-transfer coefficients high, the velocity of the process fluid within the tube should also be high. As a result, heat exchangers for three-phase flow may require less than five tubes -- each having a required linear length that could exceed several hundred feet. Given these limitations, it is obvious that a basic shell-and-tube heat exchanger is not the most practical solution for this purpose. An alternative for three-phase flow is a helical-coil heat exchanger. The helical-coil units offer a number of advantages, including perpendicular, counter-current flow and flexible overall dimensions for the exchanger itself. The paper presents equations for: calculating the tube-side heat-transfer coefficient; calculating the shell-side heat-transfer coefficient; calculating the heat-exchanger size; calculating the tube-side pressure drop; and calculating shell-side pressure-drop.
International Nuclear Information System (INIS)
Dielectric-barrier discharges (DBDs) in atmospheric pressure air have been studied by using a power-frequency voltage source. In this paper the electrical characteristics of DBDs using glass and alumina dielectrics have been investigated experimentally. According to the Lissajous figures of voltage-charges, it is discovered that the discharge power for an alumina dielectric is much higher than that for a glass dielectric at the same applied voltage. Also, the voltage-current curves of the glass and alumina dielectrics confirm the fact that the dielectric barriers behave like semiconducting materials at certain applied voltages. (low temperature plasma)
Neural network based PWM AC chopper fed induction motor drive
Directory of Open Access Journals (Sweden)
Venkatesan Jamuna
2009-01-01
Full Text Available In this paper, a new Simulink model for a neural network controlled PWM AC chopper fed single phase induction motor is proposed. Closed loop speed control is achieved using a neural network controller. To maintain a constant fluid flow with a variation in pressure head, drives like fan and pump are operated with closed loop speed control. The need to improve the quality and reliability of the drive circuit has increased because of the growing demand for improving the performance of motor drives. With the increased availability of MOSFET's and IGBT's, PWM converters can be used efficiently in low and medium power applications. From the simulation studies, it is seen that the PWM AC chopper has a better harmonic spectrum and lesser copper loss than the Phase controlled AC chopper. It is observed that the drive system with the proposed model produces better dynamic performance, reduced overshoot and fast transient response. .
Vargese Jegathesan; Jovitha Jerome
2008-01-01
This paper presents an efficient and reliable Genetic Algorithm-based solution for Specific Harmonic Elimination (SHE) switching pattern. This method eliminates considerable amount of lower order line voltage harmonics in Pulse Width Modulation (PWM) inverter. The determination of pulse pattern for the elimination of some lower order harmonics of a PWM inverter necessitates solving a system of nonlinear transcendental equations. Genetic Algorithm is used to solve nonlinear transcendental equa...
A Single Phase to Three Phase PFC Half-Bridge Converter Using BLDC Drive with SPWM Technique.
Directory of Open Access Journals (Sweden)
Srinu Duvvada
2014-07-01
Full Text Available In this paper, a buck half-bridge DC-DC converter is used as a single-stage power factor correction (PFC converter for feeding a voltage source inverter (VSI based permanent magnet brushless DC motor (BLDC drive. The front end of this PFC converter is a diode bridge rectifier (DBR fed from single-phase AC mains. The BLDC is used to drive a compressor load of an air conditioner through a three-phase VSI fed from a controlled DC link voltage. The speed of the compressor is controlled to achieve energy conservation using a concept of the voltage control at DC link proportional to the desired speed of the BLDC. Therefore the VSI is operated only as an electronic commutator of the BLDC. The stator current of the BLDC during step change of reference speed is controlled by a rate limiter for the reference voltage at DC link. The proposed BLDC drive with voltage control based PFC converter is designed, modeled and its performance is simulated in Matlab-Simulink environment for an air conditioner compressor driven through a 1.5 kW, 1500 rpm BLDC motor. The evaluation results of the proposed speed control scheme are presented to demonstrate an improved efficiency of the proposed drive system with PFC feature in wide range of the speed and an input AC voltage.
DEFF Research Database (Denmark)
Zhu, Jiebei; Guerrero, Josep M.
2014-01-01
A generic Inertia Emulation Controller (INEC) scheme for Multi-Terminal Voltage-Source-Converter based HVDC (VSC-MTDC) systems is proposed and presented in this paper. The proposed INEC can be incorporated in any Grid-side Voltage-Source-Converter (GVSC) station, allowing the MTDC terminal to contribute an inertial response to connected AC systems during system disturbances, in a fashion similar to synchronous generators. The DC link capacitors within the MTDC are utilised by the INEC scheme to exchange stored energy with the AC system by varying the overall DC voltage level of the MTDC network within a safe and pre-defined range. A theoretical treatment of the INEC algorithm and its implementation and integration within a conventional VSC control system are presented, and the impact on the total DC capacitance required within the MTDC network to ensure that DC voltages vary within an acceptable range are discussed. The proposed INEC scheme is validated using a Matlab/Simulink model under various changes in demand and in response to AC network faults. The model incorporates a multi-machine AC power system connected to a MTDC transmission system with multiple converter-interfaced nodes. The effectiveness of the INEC in damping post-fault oscillations and in enhancing AC system frequency stability is also investigated. The system is shown to perform well and is attractive for providing a stable MTDC system that is capable of providing valuable support to the connected AC systems.
Okedu, Kenneth Eloghene; Muyeen, S. M.; Takahashi, Rion; Tamura, Junji
Recent wind farm grid codes require wind generators to ride through voltage sags, which means that normal power production should be re-initiated once the nominal grid voltage is recovered. However, fixed speed wind turbine generator system using induction generator (IG) has the stability problem similar to the step-out phenomenon of a synchronous generator. On the other hand, doubly fed induction generator (DFIG) can control its real and reactive powers independently while being operated in variable speed mode. This paper proposes a new control strategy using DFIGs for stabilizing a wind farm composed of DFIGs and IGs, without incorporating additional FACTS devices. A new current controlled voltage source converter (CC-VSC) scheme is proposed to control the converters of DFIG and the performance is verified by comparing the results with those of voltage controlled voltage source converter (VC-VSC) scheme. Another salient feature of this study is to reduce the number of proportionate integral (PI) controllers used in the rotor side converter without degrading dynamic and transient performances. Moreover, DC-link protection scheme during grid fault can be omitted in the proposed scheme which reduces overall cost of the system. Extensive simulation analyses by using PSCAD/EMTDC are carried out to clarify the effectiveness of the proposed CC-VSC based control scheme of DFIGs.
Three-phase Photovoltaic Systems: Structures, Topologies, and Control
DEFF Research Database (Denmark)
Kerekes, Tamas; Sera, Dezso
2015-01-01
Photovoltaic technology has experienced unprecedented growth in the last two decades, transforming from mainly off-grid niche generation to a major renewable energy technology, reaching approximately 180 GW of capacity worldwide at the end of 2014. Large photovoltaic power plants interfacing the grid through a three-phase power electronic converter are now well on the way to becoming a major player in the power system in many countries. Therefore, this article gives an overview of photovoltaic systems with a focus on three-phase applications, presenting these both from a hardware point of view, detailing the different photovoltaic inverter structures and topologies as well as discussing the different control layers within a grid-connected photovoltaic plant. Modulation schemes for various photovoltaic inverter topologies, grid synchronization, current control, active and reactive power control, maximum power point tracking, as well as grid integration requirements and support functions are reviewed.
Accurate parameter estimation for unbalanced three-phase system.
Chen, Yuan; So, Hing Cheung
2014-01-01
Smart grid is an intelligent power generation and control console in modern electricity networks, where the unbalanced three-phase power system is the commonly used model. Here, parameter estimation for this system is addressed. After converting the three-phase waveforms into a pair of orthogonal signals via the ? ?-transformation, the nonlinear least squares (NLS) estimator is developed for accurately finding the frequency, phase, and voltage parameters. The estimator is realized by the Newton-Raphson scheme, whose global convergence is studied in this paper. Computer simulations show that the mean square error performance of NLS method can attain the Cramér-Rao lower bound. Moreover, our proposal provides more accurate frequency estimation when compared with the complex least mean square (CLMS) and augmented CLMS. PMID:25162056
Losses in armoured three-phase submarine cables
DEFF Research Database (Denmark)
Ebdrup, Thomas; Silva, Filipe Miguel Faria da
2014-01-01
The number of offshore wind farms will keep increasing in the future as a part of the shift towards a CO2 free energy production. The energy harvested from the wind farm must be brought to shore, which is often done by using a three-phase armoured submarine power cable. The use of an armour increases the losses in armoured cables compared to unarmoured cables. In this paper a thorough state of the art analysis is conducted on armour losses in three-phase armoured submarine power cables. The analysis shows that the IEC 60287-1-1 standard overestimates the armour losses which lead to the installation of cables with excessive phase conductor cross section. This paper also presents an example of the potential economic benefits of having a better knowledge of the losses introduced by the armour.
Three-Phase High-Power and Zero-Current-Switching OBC for Plug-In Electric Vehicles
Directory of Open Access Journals (Sweden)
Cheng-Shan Wang
2015-06-01
Full Text Available In this paper, an interleaved high-power zero-current-switching (ZCS onboard charger (OBC based on the three-phase single-switch buck rectifier is proposed for application to plug-in electric vehicles (EVs. The multi-resonant structure is used to achieve high efficiency and high power density, which are necessary to reduce the volume and weight of the OBC. This study focuses on the border conditions of ZCS converting with a battery load, which means the variation ranges of the output voltage and current are very large. Furthermore, a novel hybrid control method combining pulse frequency modulation (PFM and pulse width modulation (PWM together is presented to ensure a driving frequency higher than 10 kHz, and this will reduce the unexpected inner resonant power flow and decrease the total harmonic distortion (THD of the input current under a light load at the end of the charging process. Finally, a prototype is established, and experiments are carried out. According to the experimental results, the conversion efficiency is higher than 93.5%, the THD about 4.3% and power factor (PF 0.98 under the maximum power output condition. Besides, a three-stage charging process is also carried out the experimental platform.
Direct Torque Control of Three-Phase Flux Reversal Machine
D S PHANI GOPAL CHEERLA, L.MALLESWARI, DR. G R K MURTHY
2013-01-01
In this paper the mathematical model of three phase Flux Reversal Machine (FRM), electrical gear ratio of the machine and the Direct torque control of FRM is discussed. The mathematical equations are similar to that of permanent magnet synchronous machine (PMSM). The machine model is also simulated using MATLAB for the case of machine working as a motor. Output speed, flux locus and inverter output voltages are acquired at the steady state conditions.
Three phase load flow; Fluxo de carga trifasico
Energy Technology Data Exchange (ETDEWEB)
Zago, Maria Goretti
1992-12-01
The phase model which is used in the analysis and planning of electric power system is based on the hypothesis that both the transmission system and load are equilibrated. Such a system, which presents the advantage of being simple,presents satisfactory results in several cases, however, for certain applications this system is inadequate. this work presents an alternative method based on three-phase load flow which an be applied to electric power distribution networks 19 refs., 25 figs., 24 tabs.
The Rheology of Three-Phase Basaltic Magma
Llewellin, E. W.; Truby, J.; Mueller, S. P.; Mader, H. M.
2014-12-01
The transport of magma is controlled by its rheology which, in turn, is a function of its crystal and bubble content. We develop the first empirically-validated model for the rheology of a three-phase magma (i.e. one containing both bubbles and crystals). The model is valid at low bubble capillary number (where bubble deformation is small) which is typical of basaltic magma. We adopt an 'effective-medium' approach in which the bubbly melt is treated as a continuous medium which suspends the crystals. The resulting three-phase model combines separate two-phase models for bubble suspension rheology and crystal suspension rheology, which are taken from the literature. The model is validated against new analogue experimental data for three-phase suspensions of bubbles and spherical particles, collected in the low bubble capillary number regime. Good agreement is found across the experimental range of particle volume fraction (0 ? ?p ?0.5) and bubble volume fraction (0 ? ?b ? 0.3). Consistent with model predictions, experimental results demonstrate that, at low capillarity, bubble growth in a crystal-poor magma increases its viscosity, whilst bubble growth in a crystal-rich magma decreases its viscosity. The validity range of the model makes it particularly applicable to the transport of magma in the sub-volcanic plumbing system. The model is trivially extended to account for variations in crystal shape, and for the high capillarity regime; these extended models await experimental validation.
Scientific Electronic Library Online (English)
Milton E. de, Oliveira Filho; Alfeu J., Sguarezi Filho; Ernesto, Ruppert.
2012-06-01
Full Text Available Este trabalho apresenta aspectos relacionados a implementaçăo experimental de um conversor trifásico em matriz. As chaves bidirecionais empregadas na construçăo do protótipo foram construídas com a utilizaçăo de componentes discretos como IGBT's e diodos rápidos. Aspectos relacionados a proteçăo con [...] tra sobre tensăo e curto circuito, processo de comutaçăo das chaves bidirecionais e filtro de entrada săo apresentados neste trabalho juntamente com resultados experimentais da operaçăo do conversor. Abstract in english This paper presents some implementation details of a three-phase to three-phase matrix converter prototype. The bidirectional semiconductor switches were built using discrete IGBTs and fast diodes. Design aspects such as protection against overvoltage and short-circuit, commutation process of bi-dir [...] ectional switches, and input filter are addressed in this paper.
A new Zero-Current-Transition PWM switching cell
Energy Technology Data Exchange (ETDEWEB)
Grigore, V. [Electronics and Telecommunications Faculty, `Politechnica` University Bucharest (Romania); Kyyrae, J. [Helsinki University of Technology, Otaniemi (Finland): Institute of Intelligent Power Electronics
1997-12-31
In this paper a new Zero-Current-Transition (ZCT) PWM switching cell is presented. The proposed switching cell is composed of the normal hard-switched PWM cell (consisting of one active switch and one passive switch), plus as auxiliary circuit. The auxiliary circuit is inactive during the ON ad OFF intervals of the switches in the normal PWM switch. The transitions between the two states are controlled by the auxiliary circuit. Prior to turn-off, the current through the active switch in the PWM cell is forced to zero, thus the turn-off losses of the active switch are practically eliminated. At turn-on the auxiliary circuit slows down the growing rate of the current through the main switch. Thus, turn-on losses are also very much reduced. The active switch operates under ZCT conditions, the passive switch (diode) has a controlled reverse recovery, while the switch in the auxiliary circuit operates under Zero-Current-Switching (ZCS) conditions. (orig.) 3 refs.
A new Zero-Voltage-Transition PWM switching cell
Energy Technology Data Exchange (ETDEWEB)
Grigore, V. [Electronics and Telecommunications Faculty `Politebuica` University Bucharest (Romania); Kyyrae, J. [Helsinki University of Technology, Otaniemi (Finland): Institute of Intelligent Power Electronics
1997-12-31
In this paper a new Zero-Voltage-Transition (ZVT) PWM switching cell is presented. The proposed switching cell is composed of the normal hard-switched PWM cell (consisting of one active switch and one passive switch), plus an auxiliary circuit (consisting of one active switch and some reactive components). The auxiliary circuit is inactive during the ON and OFF intervals of the switches in the normal PWM switch. However, the transitions between the two states are controlled by the auxiliary circuit. Prior to turn-on, the voltage across the active switch in the PWM cell is forced to zero, thus the turn-on losses of the active switch are practically eliminated. At turn-off the auxiliary circuit behaves like a non-dissipative passive snubber reducing the turn-off losses to a great extent. Zero-Voltage-Transition switching technique almost eliminates switching losses. The active switch operates under ZVT conditions, the passive switch (diode) has a controlled reverse recovery, and the switch in the auxiliary circuit operates under Zero-Current-Switching (ZCS) conditions. (orig.) 6 refs.
Simple PWM modulator topology with excellent dynamic behavior
DEFF Research Database (Denmark)
Poulsen, SŘren; Andersen, Michael Andreas E.
2004-01-01
This paper proposes a new PWM modulator topology. The modulator is used in switch mode audio power amplifiers, but the topology can be used in a wide range of applications. Due to excellent transient behavior, the modulator is very suited for VRMs or other types of DC-DC or DC-AC applications.
Spectra of Grid Current Generated by High Power PWM Rectifiers.
Czech Academy of Sciences Publication Activity Database
Šimek, Petr; Škramlík, Ji?í; Tlustý, J.; Valouch, Viktor
Ponta Delgada - Azores : APDEE, 2011, s. 1-4. ISBN 978-972-8822-23-1. [Portuguese-Spanish Conference on Electrical Engineering - XII CLEEE /12./. Ponta Delgada - Azores (PT), 30.06.2011-02.07.2011] Institutional research plan: CEZ:AV0Z20570509 Keywords : PWM rectifier * current spectra * FCC inverter Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
PWM usm?r?ova?e velkých výkon?.
Czech Academy of Sciences Publication Activity Database
Valouch, Viktor; Šimek, Petr; Škramlík, Ji?í
Praha : ?VUT - FEL, 2010, s. 1-8. ISBN 978-80-254-8089-2. [Konference ELEN 2010. Praha (CZ), 20.09.2010-21.09.2010] R&D Projects: GA MPO FT-TA5/123 Institutional research plan: CEZ:AV0Z20570509 Keywords : PWM rectifier * multilevel converter * grid filter Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
ZAD strategy with lateral PWM applied to a Boost converter
Directory of Open Access Journals (Sweden)
Andr\\u00E9s Amador
2012-01-01
by lateral PWM (Pulse Width Modulator and ZAD (Zero Average Dynamics strategy. Different nonlinear phenomena like bifurcations and chaos are reported when the parameters associated to the system are varied. Finally, chaos present in the converter is controlled using FPIC (Fixed Point Induced Control and TDAS (Time-Delay Autosynchronization techniques.
Control Strategy of PWM Rectifiers Connected to Unbalanced Grids.
Czech Academy of Sciences Publication Activity Database
Bejvl, Martin; Švec, J.; Tlustý, J.; Valouch, V.
-, ?. 11 (2013). ISSN 2172-038X. [International Conference on Renewable Energies and Power Quality (ICREPQ´13). Bilbao, 20.03.2013-22.03.2013] Institutional support: RVO:61388998 Keywords : electric power system * PWM rectifier * dc voltage ripple Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Boosted PWM open loop control of hydraulic proportional valves
International Nuclear Information System (INIS)
This paper presents an innovative open loop control technique for direct single stage hydraulic proportional valves whose response rate is significantly higher than that obtained by standard open loop control techniques, even comparable to more costly commercial closed loop systems. Different from standard open loop techniques, which provide the coil with a constant current proportional to the target position, the control strategy proposed in this paper employs the peak and hold (P and H) technique, widely used in Diesel engine modern supply systems, to boost the duty cycle value of the pulse width modulation (PWM) signal for a short time, namely during the spool displacement, while maintaining a lower duty cycle for holding the spool in the required opening position. The developed 'boosted PWM' technique only requires a low cost microcontroller, such as a peripheral interface controller (PIC) equipped with a metal oxide semiconductor (MOS) power driver. The PWM parameters are calibrated as a function of the spool displacement so as to maximize the response rate without introducing overshoots: the collected data are stored in the PIC. Different valve opening procedures with step response have been compared to demonstrate the merits of the proposed boosted PWM technique. No overshoots have been registered. Moreover, the proposed method is characterized by a significantly higher response rate with respect to a standard open loop control, which approximately has the same cost. Similar experimental tests show that the proposed boosted PWM technique has a response rate even higher than that provided by the more costly commercial closed loop system mounted on the valve, and it produces no overshoots
Boosted PWM open loop control of hydraulic proportional valves
Energy Technology Data Exchange (ETDEWEB)
Amirante, R.; Catalano, L.A. [Dipartimento di Ingegneria Meccanica e Gestionale, Politecnico di Bari, Via Re David 200, 70125 Bari (Italy); Innone, A. [Universita degli Studi di Foggia, via Napoli, 25 Foggia (Italy)
2008-08-15
This paper presents an innovative open loop control technique for direct single stage hydraulic proportional valves whose response rate is significantly higher than that obtained by standard open loop control techniques, even comparable to more costly commercial closed loop systems. Different from standard open loop techniques, which provide the coil with a constant current proportional to the target position, the control strategy proposed in this paper employs the peak and hold (P and H) technique, widely used in Diesel engine modern supply systems, to boost the duty cycle value of the pulse width modulation (PWM) signal for a short time, namely during the spool displacement, while maintaining a lower duty cycle for holding the spool in the required opening position. The developed 'boosted PWM' technique only requires a low cost microcontroller, such as a peripheral interface controller (PIC) equipped with a metal oxide semiconductor (MOS) power driver. The PWM parameters are calibrated as a function of the spool displacement so as to maximize the response rate without introducing overshoots: the collected data are stored in the PIC. Different valve opening procedures with step response have been compared to demonstrate the merits of the proposed boosted PWM technique. No overshoots have been registered. Moreover, the proposed method is characterized by a significantly higher response rate with respect to a standard open loop control, which approximately has the same cost. Similar experimental tests show that the proposed boosted PWM technique has a response rate even higher than that provided by the more costly commercial closed loop system mounted on the valve, and it produces no overshoots. (author)
DEFF Research Database (Denmark)
Teodorescu, Remus; Blaabjerg, Frede
2004-01-01
This paper is describing the recently introduced proportional-resonant (PR) controllers and their suitability for grid-connected converters current control. It is shown that the known shortcomings associated with PI controllers like steady - state error for single-phase converters and the need of decoupling for three-phase converters can be alleviated. Additionally, selective harmonic compensation is also possible with PR controllers. Suggested control-diagrams for three-phase grid converters and active filters are also presented. A practical application of PR current control for a photovoltaic (PV) inverter is also described.
Energy Technology Data Exchange (ETDEWEB)
Svensson, Jan [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering
1996-12-01
In this paper the hybrid wind farm connected to a weak grid is investigated. By combining different electrical wind power plant systems a cost-efficient solution is obtained. The point of common connection voltage level can be controlled by injecting reactive power from a phase-compensating capacitor battery and a voltage source inverter (VSI). If the short-circuit impedance ratio is lower than 1, the demanded reactive power injection to keep the voltage at nominal level is unrealistic. For short-circuit impedance ratios of 2 or higher the demanded reactive power level is acceptable. When using both induction generators and thyristor inverters the reactive power injector VSI size should be about 0.2 pu. If the hybrid farm consists of THYs, IGs and VSIs and the active power is equally shared between the systems, the VSI had to be scaled up by 5% to handle both active and reactive power. 7 refs, 10 figs, 2 tabs
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede
2014-01-01
This paper addresses the interaction between harmonic resonant controllers and active damping of LCL resonance in voltage source converters. A virtual series R-C damper in parallel with the filter capacitor is proposed with the capacitor current feedback loop. The phase lag resulting from the digital computation and modulation delays is thus compensated by the virtual capacitor. The frequency region that allows using resonant controllers is then identified with the virtual damper. It reveals that the upper frequency limit of harmonic resonant controllers can be increased above the gain crossover frequency defined by the proportional gain of current controller. This is of particular interest for high-performance active harmonic filtering applications and low-pulse-ratio converters. Case studies in experiments validate the theoretical analysis.
Improved Passive-Damped LCL Filter to Enhance Stability in Grid-Connected Voltage-Source Converters
DEFF Research Database (Denmark)
Beres, Remus Narcis; Wang, Xiongfei
2015-01-01
This paper proposes an improved passive-damped LCL filter to be used as interface between the grid-connected voltage-source converters and the utility grid. The proposed filter replaces the LCL filter capacitor with a traditional C-type filter with the resonant circuit tuned in such a way that switching harmonics due to pulse width modulation are to be cancelled. Since the tuned circuit of the C-type filter suppresses the switching harmonics more effectively, the total inductance of the filter can be reduced. Additionally, the rating of the damping resistor is lower, compared with conventional passive-damped LCL filter. To verify the benefits of the proposed filter, a comparison with the conventional filter is made in terms of losses and ratings when both the filters are designed under the same condition.
A DSP controlled one-to-three phase matrix converter
Energy Technology Data Exchange (ETDEWEB)
Dubovsky, J.; Dobrucly, B; Tabacek, R.; Havrila, R. [Department of Electric Traction and Energetics Faculty of Electrical Engineering, University of Zilina (Slovakia)
1997-12-31
This paper deals with the theoretical analysis computer simulation and experimental results of IM fed by a one-to-three phase matrix converter which offers a unique solution for single phase electric traction applications. The proposed drive in comparison with currently used conventional drives reduces the number of power switching elements of the converter, which increases drives dependability and brings lower investment in power electronics used in drive. Further advantage is that the converter is controlled with nearly unity power factor which cuts down the operational expenses and offers higher overall performance of the drive. (orig.) 6 refs.
Program for three-phase power transformer design
Directory of Open Access Journals (Sweden)
Olivian Chiver
2011-12-01
Full Text Available This paper presents a program developed for designing three-phase power transformers used in power systems. The program was developed in Visual Basic because this programming language allows us to realize a friendly and suggestive interface with minimum effort. The second reason, which is the most important, is to use Visual Basic, because this language is recognized by the used finite elements analysis (FEA software, MagNet produced by Infolytica. This software package is designed for calculation of the magnetic field of electromagnetic devices and machines. The 3D components of the numerical model are carried out using CATIA program, automatically, based on the calculated main geometric data.
Transient three-phases three-component flow. Pt. 1
International Nuclear Information System (INIS)
Starting from the conservation principles a nonconservative form of a system of 18 quasilinear partial differential equations describing the three-phase three-component flow is obtained. The flow is described using the three-velocity field approach. Each of the flow-fields consists of one inert and one noninert component. Full thermodynamical and mechanical nonequilibrium between the fields is modelled. The simplest possible concentration and entropy equations are obtained, without any simplifying assumptions. Also the definition of the Mach number, the critical mass flow rate, and the criticality condition for this physical system is obtained. (orig.)
Experimental dynamic evaluation of three-phase reactors
Scientific Electronic Library Online (English)
F. G., Sales; L. C. A., Maranhăo; J. A. F. R., Pereira; C. A. M., Abreu.
2005-09-01
Full Text Available The hydrodynamic parameters were determined for two different three-phase systems (fluidized-bed and trickle-bed) through the experimental evaluation of the dynamic residence time distribution in the gas or liquid phase. For different fluid phase flow rates the fluidized-bed system was operated with [...] a tracer in the gas phase and in the trickle-bed with a tracer in the liquid phase. The analysis of the processes was achieved through the application of different models representing the dynamic behavior of tracers present in the gas and liquid phases with a simulation of experimental operations of the three-phase reactors. The transfer functions developed for the two systems made it possible to estimate the hydrodynamic parameters providing the gas holdup (2.22 x 10-2 to 8.42 x 10-2) and the gas phase Peclet number (54.18 to 41.20) for the fluidized-bed and the liquid holdup (0.16 to 0.25), the liquid phase Peclet number (20.37 to 4.52) and wetting efficiency (0.34 to 0.56) for the trickle-bed.
A fuzzy controlled three-phase centrifuge for waste separation
International Nuclear Information System (INIS)
The three-phase centrifuge technology discussed in this paper was developed by Neal Miller, president of Centech, Inc. The three-phase centrifuge is an excellent device for cleaning up oil field and refinery wastes which are typically composed of hydrocarbons, water, and solids. The technology is unique. It turns the waste into salable oil, reusable water, and landfill-able solids. No secondary waste is produced. The problem is that only the inventor can set up and run the equipment well enough to provide an optimal cleanup. Demand for this device has far exceeded a one man operation. There is now a need for several centrifuges to be operated at different locations at the same time. This has produced a demand for an intelligent control system, one that could replace a highly skilled operator, or at least supplement the skills of a less experienced operator. The control problem is ideally suited to fuzzy logic, since the centrifuge is a highly complicated machine operated entirely by the skill and experience of the operator. A fuzzy control system was designed for and used with the centrifuge
Three-phase CFD analytical modeling of blood flow.
Energy Technology Data Exchange (ETDEWEB)
Jung, J.; Hassanein, A.; Mathematics and Computer Science
2008-01-01
The behavior of blood cells in disturbed flow regions of arteries has significant relevance for understanding atherogenesis. However, their distribution with red blood cells (RBCs) and leukocytes is not so well studied and understood. Our three-phase computational fluid dynamics approach including plasma, RBCs, and leukocytes was used to numerically simulate the local hemodynamics in such a flow regime. This model has tracked the wall shear stress (WSS), phase distributions, and flow patterns for each phase in a concentrated suspension shear flow of blood. Unlike other computational approaches, this approach does not require dispersion coefficients as an input. The non-Newtonian viscosity model was applied to a wide physiological range of hematocrits, including low shear rates. The migration and segregation of blood cells in disturbed flow regions were computed, and the results compared favorably with available experimental data. The predicted higher leukocyte concentration was correlated with relatively low WSS near the stenosis having a high WSS. This behavior was attributed to flow-dependent interactions of the leukocytes with RBCs in pulsatile flow. This three-phase hemodynamic analysis may have application to vulnerable plaque formation in arteries with in vivo complex flow conditions.
Directory of Open Access Journals (Sweden)
Vargese Jegathesan
2008-01-01
Full Text Available This paper presents an efficient and reliable Genetic Algorithm-based solution for Specific Harmonic Elimination (SHE switching pattern. This method eliminates considerable amount of lower order line voltage harmonics in Pulse Width Modulation (PWM inverter. The determination of pulse pattern for the elimination of some lower order harmonics of a PWM inverter necessitates solving a system of nonlinear transcendental equations. Genetic Algorithm is used to solve nonlinear transcendental equations for PWM-SHE. In this proposed method, harmonics up to 17th are eliminated using Genetic Algorithm without using Dual transformer. Simulations using Matlab 7.0 and PSIM 6.1 are carried out so as to validate the solution.
Mechouma Rabiaa; Azoui Boubekeur
2014-01-01
In recent years, power demand of industrial applications has increased significantly reaching some megawatts. The use of multilevel converters for applications of medium and high powers is proposed as a solution to drawback semiconductor technology. A multilevel converter not only achieves high power ratings, but also enables the use of renewable energy sources. Renewable energy sources such as photovoltaic can be easily interfaced to a multilevel converter...
A microcontroller based voltage space vector modulator suitable for induction motor drives
Minas, Graça; Martins, Júlio S.; Couto, Carlos
1999-01-01
Pulse width modulation techniques (PWM), introduced two decades ago, are the most used methods to control the voltage and frequency supplied to electrical AC machines. This paper describes a pulse width modulator based on the voltage space vectors technique that accepts voltage demands in dq coordinates and generates three phase PWM waveforms to drive a variable frequency voltage source inverter. A scheme based on a high performance 16 bit standard microcontroller with minimum of additional h...
Single-carrier phase-disposition PWM implementation for multilevel flying capacitor converters
Ghias, Amer M.Y.M.; Pou Félix, Josep; Capellá Frau, Gabriel José; Agelidis, Vassilios; Aguilera, Ricardo P; Meynard, Thierry A.
2015-01-01
This letter proposes a new implementation of phase-disposition pulse-width modulation (PD-PWM) for multilevel flying capacitor (FC) converters using a single triangular carrier. The proposed implementation is much simpler than conventional PD-PWM techniques based on multiple trapezoidal-shaped carriers, generates the same results as far as natural capacitor voltage balance is concerned and offers better quality line-to-line voltages when compared to phase-shifted PWM. The proposed algorithm i...
Controlling DC Motor using Microcontroller (PIC16F72) with PWM
Shruti Shrivastava1 , Jageshwar Rawat2 , Amit Agrawal3
2012-01-01
Motion control plays a vital role in industrial atomization. Different types of motors AC, DC, SERVO or stepper are used depending upon the application; of these DC motors are widely used because of easier controlling. Among the different control methods for DC motor armature voltage control method using pulse width modulation (PWM) is best one. We can realize the PWM using H-bridge built with IGBT switches or transistors. To generate PWM signals we use PIC16F7...
Analysis and Design of a Higher Current ZVS-PWM Converter for Industrial Applications
Directory of Open Access Journals (Sweden)
Navid Golbon
2013-03-01
Full Text Available A new auxiliary circuit that can be implemented in DC-DC and AC-DC ZVS-PWM converters is proposed in the paper. The circuit is for ZVS-PWM converters used in applications where high-frequency operation is needed and the load current is higher than that of typical ZVS-PWM converters. In the paper, the operation of a new ZVS-PWM converter is described, its steady-state operation is analyzed, and a procedure for its design is derived and then demonstrated. The feasibility of the new converter is confirmed by experimental results obtained from a prototype.
Soft Switched Multi-Output PWM DC-DC Converter
Directory of Open Access Journals (Sweden)
Rashmi Sharma
2013-07-01
Full Text Available In this paper, a new soft switched cell that overcomes most of the drawbacks of the normal "hard switched-pulse width modulation" converter is proposed to contrive a new family of soft switched PWM converters. All of the semiconductor devices in this converter are turned on and off under exact or near zero voltage switching (ZVS and/or zero current switching (ZCS. No additional voltage and current stresses on the main switch and main diode occur. A push-pull converter equipped with the proposed snubber cell is analyzed in detail. The predicted operation principles and theoretical analysis of the presented converter are verified with a prototype of a 50W PWM push-pull multi-output converter with insulated MOSFET and for regulation of slave outputs magnetic amplifier post regulators are considered as post regulators. Moreover; this multioutput converter has a simple structure, low cost, and ease of control circuitry.
Three Phase High Power Quality Two- Stage Boost Rectifier
Directory of Open Access Journals (Sweden)
P.NAMMALVAR
2012-04-01
Full Text Available Three-phase two-stage boost rectifier with sinusoidal input current are presented and a novel topology with two active power devices is proposed. These contain a capacitor for pumping action in DC circuit. This gives twostage boost operation to obtain higher DC output voltage. The rectifier can be operated in the switch mode forpumping action and for forcing the input current to follow its sinusoidal reference independent of the working conditions. The results of the proposed rectifier are compared with those of the rectifier with a single active power device. The simulation result gives the better output DC voltage regulation under open loop condition. The simulated results prove that the proposed rectifier has the expected performance.
Advanced nonlinear control of three phase series active power filter
Directory of Open Access Journals (Sweden)
Abouelmahjoub Y.
2014-01-01
Full Text Available The problem of controlling three-phase series active power filter (TPSAPF is addressed in this paper in presence of the perturbations in the voltages of the electrical supply network. The control objective of the TPSAPF is twofold: (i compensation of all voltage perturbations (voltage harmonics, voltage unbalance and voltage sags, (ii regulation of the DC bus voltage of the inverter. A controller formed by two nonlinear regulators is designed, using the Backstepping technique, to provide the above compensation. The regulation of the DC bus voltage of the inverter is ensured by the use of a diode bridge rectifier which its output is in parallel with the DC bus capacitor. The Analysis of controller performances is illustrated by numerical simulation in Matlab/Simulink environment.
Mass transfer in three-phase fluidized beds
International Nuclear Information System (INIS)
The effects of superficial liquid and gas velocity, particle diameter, liquid viscosity, and column diameter on liquid dispersion (E/sub L) and mass transfer (K/sub L/a) in three-phase fluidized beds were investigated using a water--glycerol/oxygen--nitrogen (or oxygen--argon)/glass-bead system. Overall mass transfer coefficients were calculated based on plug flow, dispersed plug flow, and continuously stirred tank models. k/sub L/a was found to increase with gas velocity and particle diameter, but no correlation of K/sub L/a with liquid velocity was observed. At low liquid velocities, K/sub L/a was lower for the more viscous liquid; the reverse was true at high liquid flow rates. E/sub L/ increased rapidly for liquid flow rates at two to three times the minimum fluidization velocity
Mucormycosis and bone scintillography of three phases. Case description
International Nuclear Information System (INIS)
The purpose of presenting this work, besides the interest that shows the mucormycosis pathology not so frequent, it is to carry out a clinical correlation photographic with the imagenology, particularly with the bone scintillography. In the Nuclear Medicine Service it is carried out bone scintillography of three phases previous endovenous administration of 30 mCi (1110 MBq) of 99m Tc-MDP. The images are obtained with a gamma camera model Elscint APEX SPX, first each 2 seconds during the first minute, then early image to the 5 minutes and finally the late ones to the 3 hs. The bone scintillography in the phases 2 and 3 detects bigger radioactive density in left hemi side, with increment of the osteoblast activity mainly in the medial border and the floor of the orbit, in the malar bone and a little more tenuous in the superior maxillary. (Author)
Three-phase radionuclide bone imaging in sports medicine
International Nuclear Information System (INIS)
Three-phase radionuclide bone (TPB) imaging was performed on 238 patients with sports-related injuries. A wide variety of lesions was encountered, but the most frequent lesions seen were stress fractures of the lower part of the leg at the junction of the middle and distal thirds of the posterior tibial cortex (42 of 79 lesions). There were no differences in the type, location, or distribution of lesions between males and females or between competitive and noncompetitive athletes. In 110 cases, bone stress lesions were often diagnosed when radiographs were normal, whereas subacute or chronic soft-tissue abnormalities had few specific scintigraphic features. TPB imaging provides significant early diagnostic information about bone stress lesions. Normal examination results (53 cases) exclude underlying osseous pathologic conditions
A NOVEL THREE PHASE UNITY POWER FACTOR CONVERTER
Directory of Open Access Journals (Sweden)
Bekir Sami SAZAK
1998-03-01
Full Text Available The proposed unity power factor converter system which is able to operate from a 150V three-phase supply whilst delivering the required 200V DC voltage has been built and tested. This circuit functions as a high power factor low harmonic rectifier based on the concept that the peak capacitor voltages are proportional to the line input currents. Hence the low frequency components of the capacitor voltages are also approximately proportional to the line input currents. The system can be designed to achieve nearly sinusoidal supply input currents, when operated with discontinuous resonant capacitor voltages Output power control is achieved by variations of the IGBTs switching frequency. The converter is therefore able to compensate for any changes in the load resistance. The proposed topology offers advantages, including: a relatively simple power, control and protection circuits, high power capability, and high converter efficiencies.
Acoustic wave front conjugation in a three-phase media
Pushkina, N I
2015-01-01
Acoustic wave front reversal is studied in a sandy marine sediment that contains air bubbles in its fluid fraction. The considered phase conjugation is a four-wave nonlinear parametric sound interaction process caused by nonlinear bubble oscillations which are known to be dominant in acoustic nonlinear interactions in three-phase marine sediments. Two various mechanisms of phase conjugation are studied. One of them is based on the stimulated Raman-type sound scattering on resonance bubble oscillations. The second one is associated with sound interactions with bubble oscillations which frequencies are far from resonance bubble frequencies. Nonlinear equations to solve the wave-front conjugation problem are derived, expressions for acoustic wave amplitudes with a reversed wave front are obtained and compared for various frequencies of the excited bubble oscillations.
Cellular automata approach to three-phase traffic theory
International Nuclear Information System (INIS)
The cellular automata (CA) approach to traffic modelling is extended to allow for spatially homogeneous steady state solutions that cover a two-dimensional region in the flow-density plane. Hence these models fulfil a basic postulate of a three-phase traffic theory proposed by Kerner. This is achieved by a synchronization distance, within which a vehicle always tries to adjust its speed to that of the vehicle in front. In the CA models presented, the modelling of the free and safe speeds, the slow-to-start rules as well as some contributions to noise are based on the ideas of the Nagel-Schreckenberg-type modelling. It is shown that the proposed CA models can be very transparent and still reproduce the two main types of congested patterns (the general pattern and the synchronized flow pattern) as well as their dependence on the flows near an on-ramp, in qualitative agreement with the recently developed continuum version of the three-phase traffic theory (Kerner B S and Klenov S L 2002 J. Phys. A: Math. Gen. 35 L31 ). These features are qualitatively different from those in previously considered CA traffic models. The probability of the breakdown phenomenon (i.e. of the phase transition from free flow to synchronized flow) as function of the flow rate to the on-ramp and of the flow rate on the road upstream of the on-ramp is investigated. The capacity drops at the on-ramp which occur due to the formation of different congested patterns are calculatedatterns are calculated
Application of digital PWM technology in current transducers
International Nuclear Information System (INIS)
With the development of DSP technology and mature use of PID technology,, a new program for DC or AC signal measurement is proposed. Combined with the DSP chip timer module and PID algorithm, PWM signals are generated to control the feedback circuit for the compensation current. Finally the measured current value can be obtained according to the ampere-turns compensation current and the measured current. Studies have shown that this technology enables new current transducers have high stability. (authors)
Solving the optimal PWM problem for odd symmetry waveforms.
Czech Academy of Sciences Publication Activity Database
Kujan, Petr; Hrom?ík, Martin; Šebek, Michael
Laxenburg : IFAC, 2008, s. 8672-8677. ISBN 978-3-902661-00-5. [The 17th IFAC World Congress. Seoul (KR), 06.07.2008-11.07.2008] R&D Projects: GA MŠk(CZ) 1M0567 Institutional research plan: CEZ:AV0Z10750506 Keywords : Polynomial methods * optimal PWM * selected harmonics elimination * Newton identities * Pade approximation * orthogonal polynomials * composite power sums Subject RIV: BC - Control Systems Theory
Power electronic converters PWM strategies and current control techniques
Monmasson, Eric
2013-01-01
A voltage converter changes the voltage of an electrical power source and is usually combined with other components to create a power supply. This title is devoted to the control of static converters, which deals with pulse-width modulation (PWM) techniques, and also discusses methods for current control. Various application cases are treated. The book is ideal for professionals in power engineering, power electronics, and electric drives industries, as well as practicing engineers, university professors, postdoctoral fellows, and graduate students.
Single Phase Bidirectional PWM Converter for Microgrid System
C.Kalavalli; K.ParkaviKathirvelu; Balasubramanian, R.
2013-01-01
Smart grid is a newly flourishing research area because of its viable applications and expected to address the drawback of existing grid. Microgrids are the part of the Smart grid and they are designed to supply electricity for a small community such as residential areas, universities or industrial sites. Power electronics plays a vital role for connecting the renewable energy sources to Microgrid system. This paper deals the Microgrid connected single phase Bidirectional PWM converter which ...
Current Constraints of PWM Rectifier under Unbalanced Voltage Supply.
Czech Academy of Sciences Publication Activity Database
Chomát, Miroslav; Schreier, Lud?k; Bendl, Ji?í
Palm Springs, California : IEEE, 2010, s. 895-900. ISBN 978-1-4244-4783-1. ISSN 1048-2334. [Annual IEEE Applied Power Electronics Conference and Exposition - APEC 2010 /25./. Palm Springs, California (US), 21.02.2010-25.02.2010] R&D Projects: GA ?R GA102/09/1273 Institutional research plan: CEZ:AV0Z20570509 Keywords : PWM rectifiers * electric drives * DC-link voltage Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering www.apec-conf.org
Energy Technology Data Exchange (ETDEWEB)
Eskola, M.
2006-07-01
In this thesis the sensorless control of a permanent magnet synchronous motor (PMSM) is studied. The study has two main purposes. The first is to find a simple and effective method to estimate the rotor position and angular speed of the PMSM. The second is to test the applicability of a matrix converter in sensorless PMSM drives. A matrix converter (MC) enables a direct frequency conversion without DC-link with energy storage. In this thesis two matrix converter topologies, direct and indirect, are studied. The vector modulation and the current commutation strategies of a matrix converter are described. Non-ideal properties of frequency converters such as dead times, overlapping times and voltage losses over semiconductors are disturbances for a control system and position estimator. These non-idealities are studied and the properties of a conventional voltage source inverter are compared to direct and indirect MC topologies. The rotor position and angular speed of the PMSM can be estimated by various methods. Estimators can be divided into model based estimators and signal injection estimators. Model based estimators calculate mechanical quantities using the mathematical representation of the motor. Injection methods usually exploit the saliency of the PMSM. Injected voltage creates currents which are modulated by the rotor position. The position information can be extracted from measured currents. In this thesis the best features of model based and injection estimators are combined. In the proposed hybrid method signal injection is used at low speeds and the transition to model based estimator is performed when the speed increases. The estimator methods used in the hybrid estimator are selected by a comparative analysis and simulations. The most important criteria in the selection of the estimator method in this thesis are: simple algorithm and no need for modification of the modulator software or frequency converter. The suitability of the proposed hybrid estimator is tested by simulations and experimental tests in various operating conditions. To test the performance of the matrix converter the experiments are carried out using both MC topologies and a conventional voltage source converter. The results obtained show that a matrix converter can be used in PMSM drives where the speed and position of the PMSM are not measured. The proposed estimator method is stable over the nominal speed range including the zero speed region with full load torque. (orig.)
Dynamics of IGBT based PWM Converter A Case Study
Directory of Open Access Journals (Sweden)
Vijay Shukla
2012-04-01
Full Text Available Optimizing the efficiency and dynamics of power converters is a critical tradeoff in power electronics. The increase of switching frequency can improve the dynamics of power converters, but theefficiency may be degraded as well as the switching losses. As power semiconductor devices like diodes, MOSFETS, IGBTs, Thyristors, BJTs have their own characterstics and dynamic responses. It is desired toanalyze and observe the dynamics of different semiconductor devices before they actually employed in the model. Inclusion of different PWM techniques help in the removal of power line interferences like harmonic losses, unwanted ripples, chopped frequencies, spikes. In this paper, we have studied and analyzed the dynamics of IGBT based PWM converter with subjected to different conditions like transient state, steady state feeding the RLC load. Snubber circuits are used to reduce the switching losses. The IGBT based PWM converter reflects the better dynamics with improved efficiency and reduced harmonics as compared to some other power semiconductor devices when FFT is performed and subjected to standard parameterized RLC load understeady state and transient analysis.
Energy Technology Data Exchange (ETDEWEB)
Suul, Jon Are
2012-03-15
Three-Phase Voltage Source Converters (VSCs) are finding widespread applications in grid integrated power conversion systems. The control systems of such VSCs are in an increasing number of these applications required to operate during voltage disturbances and unbalanced conditions. Control systems designed for grid side voltagesensor-less operation are at the same time becoming attractive due to the continuous drive for cost reduction and increased reliability of VSCs, but are not commonly applied for operation during unbalanced conditions. Methods for voltage-sensor-less grid synchronization and control of VSCs under unbalanced grid voltage conditions will therefore be the main focus of this Thesis. Estimation methods based on the concept of Virtual Flux, considering the integral of the converter voltage in analogy to the flux of an electric machine, are among the simplest and most well known techniques for achieving voltage-sensor-less grid synchronization. Most of the established techniques for Virtual Flux estimation are, however, either sensitive to grid frequency variations or they are not easily adaptable for operation under unbalanced grid voltage conditions. This Thesis addresses both these issues by proposing a simple approach for Virtual Flux estimation by utilizing a frequency-adaptive filter based on a Second Order Generalized Integrator (SOGI). The proposed approach can be used to achieve on-line frequency-adaptive varieties of conventional strategies for Virtual Flux estimation. The main advantage is, however, that the SOGI-based Virtual Flux estimation can be arranged in a structure that achieves inherent symmetrical component sequence separation under unbalanced conditions. The proposed method for Virtual Flux estimation can be used as a general basis for voltage-sensor-less grid synchronization and control during unbalanced conditions. In this Thesis, the estimated Virtual Flux signals are used to develop a flexible strategy for control of active and reactive power flow, formulated as generalized equations for current reference calculation. A simple, but general, implementation is therefore achieved, where the control objective and the power flow characteristics can be selected according to the requirements of any particular application. Thus, the same control structure can be used to achieve for instance balanced sinusoidal currents or elimination of double frequency active power oscillations during unbalanced conditions. In case of voltage sags, current references corresponding to a specified active or reactive power flow might exceed the current capability of the converter. The limits for active and reactive power transfer during unbalanced conditions have therefore been analyzed, and generalized strategies for current reference calculation when operating under current limitations have been derived. The specified objectives for active and reactive power flow characteristics can therefore be maintained during unbalanced grid conditions, while the average active and reactive power flow is limited to keep the current references within safe values. All concepts and techniques proposed in this Thesis have been verified by simulations and laboratory experiments. The SOGI-based method for Virtual Flux estimation and the strategies for active and reactive power control with current limitation can also be easily adapted for a wide range of applications and can be combined with various types of inner loop control structures. Therefore, the proposed approach can potentially be used as a general basis for Virtual Flux-based voltage-sensor-less operation of VSCs under unbalanced grid voltage conditions.(Author)
Lee, Ho-Young; Kang, In Man; Shon, Chae-Hwa; Lee, Se-Hee
2015-05-01
A variable inductor with magnetorheological (MR) fluid has been successfully applied to power electronics applications; however, its thermal characteristics have not been investigated. To evaluate the performance of the variable inductor with respect to temperature, we measured the characteristics of temperature rise and developed a numerical analysis technique. The characteristics of temperature rise were determined experimentally and verified numerically by adopting a multiphysics analysis technique. In order to accurately estimate the temperature distribution in a variable inductor with an MR fluid-gap, the thermal solver should import the heat source from the electromagnetic solver to solve the eddy current problem. To improve accuracy, the B-H curves of the MR fluid under operating temperature were obtained using the magnetic property measurement system. In addition, the Steinmetz equation was applied to evaluate the core loss in a ferrite core. The predicted temperature rise for a variable inductor showed good agreement with the experimental data and the developed numerical technique can be employed to design a variable inductor with a high-frequency pulsed voltage source.
Mathematical modeling of a three-phase trickle bed reactor
Scientific Electronic Library Online (English)
J. D., Silva; C. A. M., Abreu.
2012-09-01
Full Text Available The transient behavior in a three-phase trickle bed reactor system (N2/H2O-KCl/activated carbon, 298 K, 1.01 bar) was evaluated using a dynamic tracer method. The system operated with liquid and gas phases flowing downward with constant gas flow Q G = 2.50 x 10-6 mł s-1 and the liquid phase flow (Q [...] L) varying in the range from 4.25x10-6 mł s-1 to 0.50x10-6 mł s-1. The evolution of the KCl concentration in the aqueous liquid phase was measured at the outlet of the reactor in response to the concentration increase at reactor inlet. A mathematical model was formulated and the solutions of the equations fitted to the measured tracer concentrations. The order of magnitude of the axial dispersion, liquid-solid mass transfer and partial wetting efficiency coefficients were estimated based on a numerical optimization procedure where the initial values of these coefficients, obtained by empirical correlations, were modified by comparing experimental and calculated tracer concentrations. The final optimized values of the coefficients were calculated by the minimization of a quadratic objective function. Three correlations were proposed to estimate the parameters values under the conditions employed. By comparing experimental and predicted tracer concentration step evolutions under different operating conditions the model was validated.
Three-phase-boundary dynamics at Pt/YSZ microelectrodes
Energy Technology Data Exchange (ETDEWEB)
Nielsen, J.; Jacobsen, T. [Department of Chemistry, Technical University of Denmark, DK-2800 (Denmark)
2007-05-31
Strong electrode activation, inductive hysteresis and non-linearity are well-known phenomena on model Pt-YSZ cathodes, and recently also a regular current fluctuation pattern have been reported. The oxygen electrode reaction with YSZ as electrolyte is studied at Pt microelectrodes prepared by electrochemical etching of platinum wire. The result is a well-defined contact area of {proportional_to} 25 {mu}m in diameter. Due to the small size and a favourable ratio between the three-phase-boundary (TPB) length and the contact area, microelectrodes should have an increased sensitivity to local events at the TPB compared to larger point electrodes normally applied. The electrode processes are studied by potential sweep, step and impedance techniques. Investigation of the YSZ and Pt surfaces afterwards reveals the growth of dendrite-like Pt structures from the TPB. The formation of these structures can explain the observed regular current fluctuation pattern and contributes to the explanation of the activation phenomena of the model Pt-YSZ and SOFC cathodes. (author)
High flexibility and low cost digital implementation for modern PWM strategies
DEFF Research Database (Denmark)
Mathe, Laszlo; Sera, Dezso
2011-01-01
In this paper a new low cost technique for PWM strategy implementation is presented. The proposed technique does not require dedicated hardware PWM units, thus offering higher flexibility of use. Furthermore, the aforementioned method eases the digital implementation of modern modulation methods like AZSPWM, NSPWM, or ACRPWM. By using a conventional PWM unit from a microcontroller, these modern modulation techniques are often difficult, or even impossible, to implement. The proposed method can be used to implement PWM strategies even for those microcontrollers which are not equipped with hardware PWM unit. The experimental results show that this new technique is suitable to replace traditional implementation methods with minimum computational overhead, with the benefit of high flexibility, lower cost and faster code development.
ADVANCED COMPUTATIONAL MODEL FOR THREE-PHASE SLURRY REACTORS
International Nuclear Information System (INIS)
In this project, an Eulerian-Lagrangian formulation for analyzing three-phase slurry flows in a bubble column was developed. The approach used an Eulerian analysis of liquid flows in the bubble column, and made use of the Lagrangian trajectory analysis for the bubbles and particle motions. The bubble-bubble and particle-particle collisions are included the model. The model predictions are compared with the experimental data and good agreement was found An experimental setup for studying two-dimensional bubble columns was developed. The multiphase flow conditions in the bubble column were measured using optical image processing and Particle Image Velocimetry techniques (PIV). A simple shear flow device for bubble motion in a constant shear flow field was also developed. The flow conditions in simple shear flow device were studied using PIV method. Concentration and velocity of particles of different sizes near a wall in a duct flow was also measured. The technique of Phase-Doppler anemometry was used in these studies. An Eulerian volume of fluid (VOF) computational model for the flow condition in the two-dimensional bubble column was also developed. The liquid and bubble motions were analyzed and the results were compared with observed flow patterns in the experimental setup. Solid-fluid mixture flows in ducts and passages at different angle of orientations were also analyzed. The model predictions were compared with the experimental data and good agreement was found. Gravity chute flows of solid-liquid mixtures were also studied. The simulation results were compared with the experimental data and discussed A thermodynamically consistent model for multiphase slurry flows with and without chemical reaction in a state of turbulent motion was developed. The balance laws were obtained and the constitutive laws established
ADVANCED COMPUTATIONAL MODEL FOR THREE-PHASE SLURRY REACTORS
Energy Technology Data Exchange (ETDEWEB)
Goodarz Ahmadi
2004-10-01
In this project, an Eulerian-Lagrangian formulation for analyzing three-phase slurry flows in a bubble column was developed. The approach used an Eulerian analysis of liquid flows in the bubble column, and made use of the Lagrangian trajectory analysis for the bubbles and particle motions. The bubble-bubble and particle-particle collisions are included the model. The model predictions are compared with the experimental data and good agreement was found An experimental setup for studying two-dimensional bubble columns was developed. The multiphase flow conditions in the bubble column were measured using optical image processing and Particle Image Velocimetry techniques (PIV). A simple shear flow device for bubble motion in a constant shear flow field was also developed. The flow conditions in simple shear flow device were studied using PIV method. Concentration and velocity of particles of different sizes near a wall in a duct flow was also measured. The technique of Phase-Doppler anemometry was used in these studies. An Eulerian volume of fluid (VOF) computational model for the flow condition in the two-dimensional bubble column was also developed. The liquid and bubble motions were analyzed and the results were compared with observed flow patterns in the experimental setup. Solid-fluid mixture flows in ducts and passages at different angle of orientations were also analyzed. The model predictions were compared with the experimental data and good agreement was found. Gravity chute flows of solid-liquid mixtures were also studied. The simulation results were compared with the experimental data and discussed A thermodynamically consistent model for multiphase slurry flows with and without chemical reaction in a state of turbulent motion was developed. The balance laws were obtained and the constitutive laws established.
Soft Switched Multi-Output PWM DC-DC Converter
Rashmi Sharma
2013-01-01
In this paper, a new soft switched cell that overcomes most of the drawbacks of the normal "hard switched-pulse width modulation" converter is proposed to contrive a new family of soft switched PWM converters. All of the semiconductor devices in this converter are turned on and off under exact or near zero voltage switching (ZVS) and/or zero current switching (ZCS). No additional voltage and current stresses on the main switch and main diode occur. A push-pull converter equipped with the prop...
Spread Spectrum Modulation by Using Asymmetric-Carrier Random PWM
DEFF Research Database (Denmark)
Mathe, Laszlo; Lungeanu, Florin
2012-01-01
This paper presents a new fixed carrier frequency random PWM method, where a new type of carrier wave is proposed for modulation. Based on simulations and experimental measurements, it is shown that the spread effect of the discrete components from the motor current spectra and acoustic spectra is very effective and is independent from the modulation index. The flat motor current spectrum generates an acoustical noise close to the white noise, which improves the acoustical performance of the drive. The new carrier wave is easy to implement digitally, without employing any external circuits. The modulation method can be used in both open and closed loop motor control applications.
A REVIEW ON OPTIMIZATION OF ENERGY BY USING PWM INVERTER
Directory of Open Access Journals (Sweden)
Mr. Ravindra Patil. ,Prof. M.H. Nerkar,Mr. Prashant Chaudhari
2013-01-01
Full Text Available An important part of uninterruptable powersupply is the DC to AC inverter which converts the DCvoltage from a battery to an AC voltage that is required tooperate electronic circuits. These inverters are bulky innature & consume most of the power. Therefore poweravailable at the output of inverter is less. So it is the goal ofthis paper to develop a DC/AC inverter capable ofproducing a pure sine wave which will consume less power.In this paper, we detail how the inverter’s controls wereimplemented with a digital approach using amicrocontroller for the control system and how effective andenergy efficient a PWM (Pulse Width Modulation invertercan be.
Midtsund, Tarjei
2010-01-01
The performance of different current controller structures for Voltage Source Converters (VSC) under weak grid conditions caused by large grid impedance is investigated. The VSC is synchronized to the grid by a Phase Locked Loop (PLL). Current control techniques and PLL techniques for handling both symmetrical and asymmetrical conditions are presented and discussed. The investigated current control structures are; the conventional Proportional Integral (PI)-controller in the synchronous rotat...
Directory of Open Access Journals (Sweden)
Prechanon Kumkratug
2011-01-01
Full Text Available Abstract: Problem statement: Static Synchronous Compensator (STATCOM and Static Synchronous Series Compensator (SSSC have been individually applied to improve stability of power system. Approach: This study presents the coordination of a STATCOM and SSSC for improving power system stability. The swing curves of the three phase faulted power system with various cases are tested and compared. Results: The swing curve of system without FACTS devices has undamped oscillation. The system with a STATCOM or a SSSC can increase damping of power system whereas the system with coordination of a STATCOM and a SSSC provides the best results of stability improvement Conclusion: From the simulation results, the stability of power system can be much better improved by coordination control of a STATCOM and a SSSC.
An Improved Switching Period Optimization Space Vector PWM Strategy
Directory of Open Access Journals (Sweden)
Guoqiang Chen
2014-01-01
Full Text Available In order to improve the performance of space vector PWM (pulse width modulation, the optimization is widely used. The switching period optimization space vector PWM can reduce both total harmonic distortion and spectrum peaks, so it has important application prospects and has been widely discussed among several types of optimization strategies. Aiming at the characteristic of uncontrollable switching frequency, the study proposes an improved optimization method that can be used in both steady and non-steady states. The method uses a time window with adaptive width to control the average switching period and divides the value range of reference voltage vectors into two kinds of regions: R and Q based on period coefficients. Switching periods are dependent in the same time window, while independent in different windows. The total extra time between specified periods and optimal periods in region R can be made full use of in region Q. A simulation platform was built in software MATLAB/Simulink. The simulation result verifies excellent performance on harmonic distortion and amplitude peak reduction. The improved strategy has widespread applications in electric vehicles, industry automation and drives, household appliances and so on.
PWM Based Automatic Closed Loop Speed Control of DC Motor
Directory of Open Access Journals (Sweden)
Atul Kumar Dewangan, Nibbedita Chakraborty, Sashi Shukla, Vinod Yadu
2012-04-01
Full Text Available The electric drive systems used in many industrial applications require higher performance, reliability, variable speed due to its ease of controllability. The speed control of DC motor is very crucial in applications where precision and protection are of essence. Purpose of a motor speed controller is to take a signal representing the required speed and to drive a motor at that speed. Microcontrollers can provide easy control of DC motor. Microcontroller based speed control system consist of electronic component, microcontroller and the LCD. In this paper, implementation of the ATmega8L microcontroller for speed control of DC motor fed by a DC chopper has been investigated. The chopper is driven by a high frequency PWM signal. Controlling the PWM duty cycle is equivalent to controlling the motor terminal voltage, which in turn adjusts directly the motor speed. This work is a practical one and high feasibility according to economic point of view and accuracy. In this work, development of hardware and software of the close loop dc motor speed control system have been explained and illustrated. The desired objective is to achieve a system with the constant speed at any load condition. That means motor will run at a fixed speed instead of varying with amount of load.
Distortion-Free 1-Bit PWM Coding for Digital Audio Signals
Directory of Open Access Journals (Sweden)
John Mourjopoulos
2007-01-01
Full Text Available Although uniformly sampled pulse width modulation (UPWM represents a very efficient digital audio coding scheme for digital-to-analog conversion and full-digital amplification, it suffers from strong harmonic distortions, as opposed to benign non-harmonic artifacts present in analog PWM (naturally sampled PWM, NPWM. Complete elimination of these distortions usually requires excessive oversampling of the source PCM audio signal, which results to impractical realizations of digital PWM systems. In this paper, a description of digital PWM distortion generation mechanism is given and a novel principle for their minimization is proposed, based on a process having some similarity to the dithering principle employed in multibit signal quantization. This conditioning signal is termed “jither” and it can be applied either in the PCM amplitude or the PWM time domain. It is shown that the proposed method achieves significant decrement of the harmonic distortions, rendering digital PWM performance equivalent to that of source PCM audio, for mild oversampling (e.g., ×4 resulting to typical PWM clock rates of 90 MHz.
Distortion-Free 1-Bit PWM Coding for Digital Audio Signals
Directory of Open Access Journals (Sweden)
Mourjopoulos John
2007-01-01
Full Text Available Although uniformly sampled pulse width modulation (UPWM represents a very efficient digital audio coding scheme for digital-to-analog conversion and full-digital amplification, it suffers from strong harmonic distortions, as opposed to benign non-harmonic artifacts present in analog PWM (naturally sampled PWM, NPWM. Complete elimination of these distortions usually requires excessive oversampling of the source PCM audio signal, which results to impractical realizations of digital PWM systems. In this paper, a description of digital PWM distortion generation mechanism is given and a novel principle for their minimization is proposed, based on a process having some similarity to the dithering principle employed in multibit signal quantization. This conditioning signal is termed "jither" and it can be applied either in the PCM amplitude or the PWM time domain. It is shown that the proposed method achieves significant decrement of the harmonic distortions, rendering digital PWM performance equivalent to that of source PCM audio, for mild oversampling (e.g., resulting to typical PWM clock rates of 90 MHz.
Generalisation of Helmholtz-Thevenin theorem to three-phase electrical circuits
Mihai, Gheorghe
2009-01-01
The scope of this paper is to determine the generalized form for equivalent tension generator theorem (Helmholtz-Thevenin theorem) for three-phase electrical circuit. Any complicated electrical power systems we can reduce depending on any three-phase electrical consumer to a three-phase electrical generator that has certain internal impedance. Starting with this assumption, we have demonstrated the way to obtain the electromotive voltages for an equivalent generator and its internal impedances.
Generalisation of Helmholtz-Thevenin theorem to three-phase electrical circuits
Mihai, Gheorghe
2009-01-01
The scope of this paper is to determine the generalized form for equivalent tension generator theorem (Helmholtz-Thevenin theorem) for three-phase electrical circuit. Any complicated electrical power systems we can reduce depending on any three-phase electrical consumer to a three-phase electrical generator that has certain internal impedance. Starting with this assumption, we have demonstrated the way to obtain the electromotive voltages for an equivalent generator and its ...
Controlling DC Motor using Microcontroller (PIC16F72 with PWM
Directory of Open Access Journals (Sweden)
Shruti Shrivastava1 , Jageshwar Rawat2 , Amit Agrawal3
2012-12-01
Full Text Available Motion control plays a vital role in industrial atomization. Different types of motors AC, DC, SERVO or stepper are used depending upon the application; of these DC motors are widely used because of easier controlling. Among the different control methods for DC motor armature voltage control method using pulse width modulation (PWM is best one. We can realize the PWM using H-bridge built with IGBT switches or transistors. To generate PWM signals we use PIC16F72 microcontroller.
Soft-switching PWM full-bridge converters topologies, control, and design
Ruan, Xinbo
2014-01-01
Soft-switching PWM full-bridge converters have been widely used in medium-to-high power dc-dc conversions for topological simplicity, easy control and high efficiency. Early works on soft-switching PWM full-bridge converter by many researchers included various topologies and modulation strategies. However, these works were scattered, and the relationship among these topologies and modulation strategies had not been revealed. This book intends to describe systematically the soft-switching techniques for pulse-width modulation (PWM) full-bridge converters, including the topologies, control and
Implementation and Analytical Model of Three-Phase Four-Switch Power Factor Corrector.
Czech Academy of Sciences Publication Activity Database
Klíma, J.; Škramlík, Ji?í; Valouch, Viktor
Sevilla : EA4EPQ, 2007, s. 1-4. ISBN 978-84-611-4707-6. [International Conference on Renewable Energies and Power Quality - ICREPQ 07. Sevilla (ES), 28.03.2007-30.03.2007] R&D Projects: GA AV ?R IAA200760703 Institutional research plan: CEZ:AV0Z20570509 Keywords : SV PWM * four-switch converter * AD-DC power converters Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Three-Phase Four-Switch PFC and Its Analytical Model.
Czech Academy of Sciences Publication Activity Database
Klíma, J.; Škramlík, Ji?í; Valouch, Viktor
Setúbal : Escola Superior de Tecnologia - IEEE, 2007, s. 66-71. ISBN 1-4244-0895-4. [International Conference on Power Engineering, Energy and Electrical Drives. Setúbal (PT), 12.04.2007-14.04.2007] R&D Projects: GA AV ?R IAA200760703 Institutional research plan: CEZ:AV0Z20570509 Keywords : four-switch converter * space-vector PWM * closed-form solution Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Three-Phase and Six-Phase AC at the Lab Bench
Caplan, George M.
2009-01-01
Utility companies generate three-phase electric power, which consists of three sinusoidal voltages with phase angles of 0 degrees, 120 degrees, and 240 degrees. The ac generators described in most introductory textbooks are single-phase generators, so physics students are not likely to learn about three-phase power. I have developed a simple way…
A PWM transistor inverter for an ac electric vehicle drive
Slicker, J. M.
1981-01-01
A prototype system consisting of closely integrated motor, inverter, and transaxle has been built in order to demonstrate the feasibility of a three-phase ac transistorized inverter for electric vehicle applications. The microprocessor-controlled inverter employs monolithic power transistors to drive an oil-cooled, three-phase induction traction motor at a peak output power of 30 kW from a 144 V battery pack. Transistor safe switching requirements are discussed, and a circuit is presented for recovering trapped snubber inductor energy at transistor turn-off.
Directory of Open Access Journals (Sweden)
Md. Aziz Ul Huq
2013-05-01
Full Text Available The speed of a three-phase induction motor can be varied within a wide range other than its rated value if its input parameters (frequency, voltages are varied properly. For industrial, mainly in knitting and some other sophisticated use of three-phase induction motor, precise and accurate control of the speed of the motor is necessary. The present three-phase inverter is so designed that its input parameters can be easily varied through proper software program and computer interfacing hardware. N-channel MOSFET is used as power device but may be replaced with IGBT. A special one way delay circuit is introduced to ensure non short circuit situation. The input frequency to the inverter can be varied by varying the input voltage to the Voltage Controlled Oscillator (VCO. The proper input voltage to the inverter is set by Automatic Voltage Regulator (AVR instructed by the computer. Though the frequency of the inverter can be varied between a wide range, the inter phase separation remains always 1200 yielding a true pattern of a three-phase power supply. Introduction of microcomputer and associate of software programs in three-phase induction motor control system as proposed is accurate and reliable in terms of accurate and complex speed control of the motor.
Determining the optimal operator allocation using a three-phase methodology
Rani, Ruzanita Mat; Ismail, Wan Rosmanira; Ab Rahman, Mohd Nizam
2014-09-01
This paper presents the operator allocation decision in labor-intensive manufacturing system using a three-phase methodology. A two-phase methodology from literatures has been extended to a three-phase methodology which in a three-phase methodology, operators' performance is evaluated before the allocation is made. The evaluation of operators' performance in Phase 1 is realized as a requirement in operator allocation decision because it will affect the production system's performance. In Phase 2, the used of computer simulation offered flexibility in determining inputs and outputs of each operator allocation alternative. Finally, in Phase 3 the optimal operator allocation is concluded. The combination of these three phases is essential because it includes all important factors. Hence, it will assist the management of the manufacturing companies, especially SMEs in providing ideas to determine an optimal operator allocation. Based on these findings a three-phase methodology improves the current operator allocation.
PWM Switching Frequency Effects on Eddy Current Sensors for Magnetically Suspended Flywheel Systems
Jansen, Ralph; Lebron, Ramon; Dever, Timothy P.; Birchenough, Arthur G.
2003-01-01
A flywheel magnetic bearing (MB) pulse width modulated power amplifier (PWM) configuration is selected to minimize noise generated by the PWMs in the flywheel position sensor system. Two types of noise are addressed: beat frequency noise caused by variations in PWM switching frequencies, and demodulation noise caused by demodulation of high order harmonics of the switching voltage into the MB control band. Beat frequency noise is eliminated by synchronizing the PWM switch frequencies, and demodulation noise is minimized by selection of a switching frequency which does not have harmonics at the carrier frequency of the sensor. The recommended MB PWM system has five synchronized PWMs switching at a non-integer harmonic of the sensor carrier.
Single Phase Bidirectional PWM Converter for Microgrid System
Directory of Open Access Journals (Sweden)
C.Kalavalli
2013-06-01
Full Text Available Smart grid is a newly flourishing research area because of its viable applications and expected to address the drawback of existing grid. Microgrids are the part of the Smart grid and they are designed to supply electricity for a small community such as residential areas, universities or industrial sites. Power electronics plays a vital role for connecting the renewable energy sources to Microgrid system. This paper deals the Microgrid connected single phase Bidirectional PWM converter which operates in Rectification and Inverting mode. This converter helps to connect renewable energy sources to loads as well as excess power are given to power grid. Double Loop PID control technique is used for controlling the converter for both modes. The designed Converter is simulated in MATLAB/Simulink software and results are verified using the Hardware.
CARRIER OVERLAPPING PWM METHODS FOR ASYMMETRICAL MULTILEVEL INVERTER
Directory of Open Access Journals (Sweden)
DR.R.SEYEZHAI
2011-08-01
Full Text Available Multilevel inverter has gained attention in recent years due to its high power capability associated with lower output harmonics. Several multilevel topologies have been reported in the literature and thispaper focuses on asymmetric cascaded multilevel inverter employing Carrier Overlapping PWM (COPWM technique. This technique provides reduced harmonics in the output voltage and significantly improves the root mean square value of the output voltage compared to the conventional Sinusoidal Pulse Width Modulation (SPWM. A detailed study of the proposed modulation technique is carried out throughMATLAB/SIMULINK for Total Harmonic Distortion (THD. An experimental seven-level inverter test rig has been built to implement the proposed algorithm. Gating signals are generated using PIC microcontroller. The performance of the inverter has been analyzed and compared with the result obtained from theory and simulation.
Voltage Balancing in Diode Clamped Multilevel Inverter Using Sinusoidal PWM
Directory of Open Access Journals (Sweden)
S.Shalini
2013-12-01
Full Text Available Multilevel inverters offer several advantages compared to the conventional 3-phase bridge inverter in terms of lower dv/dt stresses, lower electromagnetic compatibility, smaller rating and better output features. This project presents a 9-level diode Clamped inverter using Sinusoidal pulse width Modulation techniques as the control strategies. The algorithm has been developed within the carrier-based PWM framework to facilitate its implementation in diode clamped converters with three or more levels. A simulation model of 9-level DCMI has been designed and developed. The results obtained from the simulation model have been compared with the 3-level and 5-level diode clamped inverter. By increasing the level of inverter, effective balancing in line voltage and reduced THD is obtained.
PWM Inverter-Fed Induction Motor-Based Electrical Vehicles Fault-Tolerant Control
Tabbache, Bekheira; Benbouzid, Mohamed; Kheloui, Abdelaziz; Bourgeot, Jean-Matthieu; Mamoune, Abdeslam
2013-01-01
This paper proposes a fault-tolerant control scheme for PWM inverter-fed induction motor-based electric vehicles. The proposed strategy deals with power switch (IGBTs) failures mitigation within a reconfigurable induction motor control. In a vehicle context, 4-wire and 4-leg PWM inverter topologies are investigated and their performances discussed. Two topologies exploit the induction motor neutral accessibility for fault-tolerant purposes. The 4-wire topology uses then classical hysteresis c...
Leandro Michels; Robinson F. Camargo; Fernando Botterón; Humberto Pinheiro
2005-01-01
Este artigo apresenta uma metodologia sistematizada de projeto de filtros de saída de segunda ordem para inversores que sintetizam tensőes senoidais através de modulaçăo por largura de pulso (PWM) digital. O propósito desta metodologia é o de determinar os parâmetros do filtro que assegure a especificaçăo da máxima taxa de distorçăo harmônica total (THD) admissível nas tensőes de saída do inversor PWM, para cargas lineares e năo-lineares. A metodologia proposta é discutida em detalhes, inclui...
Directory of Open Access Journals (Sweden)
Ufa Ruslan A.
2014-01-01
Full Text Available The motivation of the presented research is based on the needs for development of new methods and tools for adequate simulation of Flexible Alternating Current Transmission System (FACTS devices and High Voltage Direct Current Transmission (HVDC system as part of real electric power systems (EPS. For that, a hybrid approach for advanced simulation of the FACTS and HVDC based on Voltage Source is proposed. The presented simulation results of the developed hybrid model of VSC confirm the achievement of the desired properties of the model and the effectiveness of the proposed solutions.
Directory of Open Access Journals (Sweden)
Marcelo Gradella Villalva
2011-06-01
Full Text Available This paper describes the modeling and control of a three-phase grid-connected converter fed by a photovoltaic array. The converter is composed of an isolated DC-DC converter and a three-phase DC-AC voltage source inverter The converters are modeled in order to obtain small-signal transfer functions that are used in the design of three closed-loop controllers: for the output voltage of the PV array, the DC link voltage and the output currents. Simulated and experimental results are presented.Este artigo descreve a modelagem e o controle de um conversor trifásico conectado ŕ rede alimentado por um conjunto fotovoltaico. O conversor é composto de um estágio CC-CC isolado um estágio CC-CA. Săo obtidas funçőes de transferęncia com as quais săo projetados tręs sistemas de controle em malha fechada: um para a tensăo de entrada do arranjo de painéis solares, um para a tensăo do do barramento de tensăo contínua e outro para as correntes trifásicas de saída.
Scientific Electronic Library Online (English)
Marcelo Gradella, Villalva; Marcos Fernando, Espindola; Thais Gama de, Siqueira; Ernesto, Ruppert.
2011-06-01
Full Text Available Este artigo descreve a modelagem e o controle de um conversor trifásico conectado ŕ rede alimentado por um conjunto fotovoltaico. O conversor é composto de um estágio CC-CC isolado um estágio CC-CA. Săo obtidas funçőes de transferęncia com as quais săo projetados tręs sistemas de controle em malha f [...] echada: um para a tensăo de entrada do arranjo de painéis solares, um para a tensăo do do barramento de tensăo contínua e outro para as correntes trifásicas de saída. Abstract in english This paper describes the modeling and control of a three-phase grid-connected converter fed by a photovoltaic array. The converter is composed of an isolated DC-DC converter and a three-phase DC-AC voltage source inverter The converters are modeled in order to obtain small-signal transfer functions [...] that are used in the design of three closed-loop controllers: for the output voltage of the PV array, the DC link voltage and the output currents. Simulated and experimental results are presented.
Tole Sutikno
2009-01-01
The space vector pulse width modulation (SV-PWM) is more suitable and can increase the obtainable DC voltage utilization ratio very much compared to others PWM. Moreover, the modulation can obtain a better voltage total harmonic distortion (THD) factor. But until now, no studies that concern at hardware resources saving to realize SV-PWM based on FPGA. This paper proposes a new technique to realize SV-PWM based on FPGA. In order to get hardware resource saving, a simple technique to judge sec...
Novel, Four-Switch, Z-Source Three-Phase Inverter
DEFF Research Database (Denmark)
Antal, Robert; Muntean, Nicolae
2010-01-01
This paper presents a new z-source three phase inverter topology. The proposed topology combines the advantages of a traditional four-switch three-phase inverter with the advantages of the z impedance network (one front-end diode, two inductors and two X connected capacitors). This new topology, besides the self-boost property, has low switch count and it can operate as a buck-boost inverter. In contrast to standard four-switch three-phase inverter which operates at half dc input voltage the proposed four-switch z-source inverter, by self boosting, brings the output voltage at same (or higher) value as in six switch standard three-phase inverter. The article presents the derivation of the equations describing the operation of the converter based on space vector analysis, validation through digital simulations in PSIM and preliminary experimental results on a laboratory setup with a dsPIC30F3011 digital signal processor.
Efficiency analysis on a two-level three-phase quasi-soft-switching inverter
DEFF Research Database (Denmark)
Geng, Pan; Wu, Weimin
2013-01-01
When designing an inverter, an engineer often needs to select and predict the efficiency beforehand. For the standard inverters, plenty of researches are analyzing the power losses and also many software tools are being used for efficiency calculation. In this paper, the efficiency calculation for non-conventional inverters with special shoot-through state is introduced and illustrated through the analysis on a special two-level three-phase quasi-soft-switching inverter. Efficiency comparison between the classical two-stage two-level three-phase inverter and the two-level three-phase quasi-soft-switching inverter is carried out. A 10 kW/380 V prototype is constructed to verify the analysis. The experimental results show that the efficiency of the new inverter is higher than that of the traditional two-stage two- level three-phase inverter.
Control of a Three Phase Induction Motor using Single Phase Supply
Directory of Open Access Journals (Sweden)
G. R. Sreehitha, A. Krishna Teja, Kondenti. P. Prasad Rao
2012-06-01
Full Text Available In Industrial applications, two forms of electrical energy are used: Direct Current (DC and Alternating Current (AC. Usually constant voltage, constant frequency Single-Phase or Three-Phase AC is readily available. However, for different applications different forms, magnitudes and/or frequencies are required. This paper proposes how the Three-Phase inductive load is run by a Single-Phase supply by using Cycloconverter and a Scott-T connected Transformer. The controlling of a ThreePhase Induction Motor is done by Frequency variable method. Single-Phase to Three-Phase for motors offered by using high in performance, low on maintenance and is used to reduce of breakdown of electrical equipment, our range is also suitable for saving energy and require low maintenance.
Vector Control of Three-Phase Induction Motor with Two Stator Phases Open-Circuit
Directory of Open Access Journals (Sweden)
Seyed Hesam Asgari
2015-06-01
Full Text Available Variable frequency drives are used to provide reliable dynamic systems and significant reduction in usage of energy and costs of the induction motors. Modeling and control of faulty or an unbalanced three-phase induction motor is obviously different from healthy three-phase induction motor. Using conventional vector control techniques such as Field-Oriented Control (FOC for faulty three-phase induction motor, results in a significant torque and speed oscillation. This research presented a novel method for vector control of three-phase induction motor under fault condition (two-phase open circuit fault. The proposed method for vector control of faulty machine is based on rotor FOC method. A comparison between conventional and modified controller shows that the modified controller has been significantly reduced the torque and speed oscillations.
Comparisons between the three-phase current injection method and the forward/backward sweep method
Energy Technology Data Exchange (ETDEWEB)
Araujo, Leandro Ramos de; Penido, Debora Rosana Ribeiro; Pereira, Jose Luiz Rezende; Garcia, Paulo Augusto Nepomuceno [Department of Electrical Engineering, Federal University of Juiz de Fora, Juiz de Fora, MG (Brazil); Junior, Sandoval Carneiro [Department of Electrical Engineering, Federal University of Rio de Janeiro, Postal Box 68504, Rio de Janeiro, RJ (Brazil)
2010-09-15
This paper presents comparisons of two power flow methodologies for distribution system analysis: the three-phase current injection method - TCIM and the forward/backward sweep - FBS. These techniques were applied for large scale three-phase distribution systems, the advantages and drawbacks are emphasized and their computational performances are presented. The results presented in this work can be helpful to decide which one of the tested methods is the most suitable to solve a particular electrical system. (author)
Fuzzy Logic Controller Based Three-phase Shunt Active Filter for Line Harmonics Reduction
C. Sharmeela; M. R. Mohan; Uma, G.; J. Baskaran
2007-01-01
Harmonic distortion is a form of electrical noise. It is a superposition of signals, which are of multiples of fundamental frequency. Proliferation of large power electronic systems results in increased harmonic distortion. Harmonic distortion results in reduction of power quality and system stability. This paper presents fuzzy control applicable for active power filter for three-phase systems, which are comprised of nonlinear loads. The active filter is based on a three-phase inverter with s...
International Nuclear Information System (INIS)
Interphase carbide precipitation due to austenite decomposition was investigated by high resolution transmission electron microscopy and atom probe tomography in tempered nanostructured bainitic steels. Results showed that cementite (?) forms by a paraequilibrium transformation mechanism at the bainitic ferrite–austenite interface with a simultaneous three phase crystallographic orientation relationship. - Highlights: • Interphase carbide precipitation due to austenite decomposition • Tempered nanostructured bainitic steels • High resolution transmission electron microscopy and atom probe tomography • Paraequilibrium ? with three phase crystallographic orientation relationship
Energy Technology Data Exchange (ETDEWEB)
Caballero, F.G. [Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avda Gregorio del Amo, 8, Madrid E-28040 (Spain); Yen, Hung-Wei [Department of Materials Science and Engineering, National Taiwan University, 1, Roosevelt Rd. Sec. 4, Taipei 10617, Taiwan (China); Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Miller, M.K. [Oak Ridge National Laboratory (ORNL), Materials Science and Technology Division, Oak Ridge, TN 37831-6139 (United States); Cornide, J. [Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avda Gregorio del Amo, 8, Madrid E-28040 (Spain); Chang, Hsiao-Tzu [Department of Materials Science and Engineering, National Taiwan University, 1, Roosevelt Rd. Sec. 4, Taipei 10617, Taiwan (China); Garcia-Mateo, C. [Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avda Gregorio del Amo, 8, Madrid E-28040 (Spain); Yang, Jer-Ren [Department of Materials Science and Engineering, National Taiwan University, 1, Roosevelt Rd. Sec. 4, Taipei 10617, Taiwan (China)
2014-02-15
Interphase carbide precipitation due to austenite decomposition was investigated by high resolution transmission electron microscopy and atom probe tomography in tempered nanostructured bainitic steels. Results showed that cementite (?) forms by a paraequilibrium transformation mechanism at the bainitic ferrite–austenite interface with a simultaneous three phase crystallographic orientation relationship. - Highlights: • Interphase carbide precipitation due to austenite decomposition • Tempered nanostructured bainitic steels • High resolution transmission electron microscopy and atom probe tomography • Paraequilibrium ? with three phase crystallographic orientation relationship.
Controlador repetitivo para inversores PWM com referęncia de freqüęncia variável
Scientific Electronic Library Online (English)
Leandro, Michels; Márcio, Stefanello; Hilton A., Gründling.
2009-09-01
Full Text Available Controladores repetitivos tęm se mostrado eficazes na rejeiçăo de distúrbios cíclicos em inversores de tensăo modulados por largura de pulso. Contudo, observa-se que estes controladores tęm seu desempenho comprometido caso seu período năo seja sincronizado com o período do sinal de referęncia, o que [...] restringe o seu uso em aplicaçőes de freqüęncia variável. Para mitigar este problema, é proposta uma modificaçăo nestes controladores para adequá-los ŕ aplicaçőes com referęncia senoidal de freqüęncia variável. O algoritmo proposto é simples, sendo apenas ajustados o comprimento das memórias circulares e os ponteiros empregados para endereçá-las nos controladores repetitivos convencionais. Resultados experimentais, obtidos em dois protótipos com especifiaçőes distintas, săo apresentados para validar a técnica proposta. Abstract in english Repetitive controllers have demonstrated efficacy in the rejection of cyclic disturbances in pulse-width modulated voltage-source inverters. However, the performance of these controllers is compromised if their period are not synchronized with the period of the reference signal. This drawback restri [...] ct their use in variable frequency applications. In order to mitigate this problem, it is proposed a modification in these controllers to make them suitable for sinusoidal references with variable frequency. The proposed algorithm is simple given that is only performed a chance in the length of circular buffers and in the pointer used to address them. Experimental results, obtained with two different prototypes, are presented to validate the proposed technique.
Directory of Open Access Journals (Sweden)
Olivier Barre
2015-06-01
Full Text Available Mutual inductance is a phenomenon caused by the circulation of the magnetic flux in the core of an electrical machine. It is the result of the effect of the current flowing in one phase on the other phases. In conventional three-phase machines, such an effect has no influence on the electrical behaviour of the device. Although these machines are powered by power inverters, no problem should occur. The result is not the same for multi-star machines. If these machines are using a conventional winding structure, namely distributed windings, and are powered by voltage source converters, current ripples appear in the power supply lines. These current ripples are related to magnetic couplings between the stars. Designers should check these current ripples in order to stay within the limits imposed by the specifications. These electric current disturbances also provide torque ripples. With concentrated windings, a new degree of freedom appears; the configuration—number of slots/number of poles—can have a positive impact. The circulation of the magnetic flux is the initial phenomenon that produces the mutual inductance. The main goal of this discussion is to describe a design method that is able to produce not only a machine with low mutual inductance between phases, but also a multi-star machine where the stars and the phases are magnetically decoupled or less coupled. This discussion only takes into account the machines that use permanent magnets mounted on the rotor surface. This article is part of a study aimed at designing a high efficiency generator using fractional-slot concentrated-windings (FSCW.
Energy Technology Data Exchange (ETDEWEB)
Garza Macias, Anibal [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)
1988-12-31
In the Mexico`s Gulf Coast and in the North East part of the country there are severe pollution problems on the electric distribution power systems insulators. To solve this problem, in specialized laboratories are reproduced the pollution conditions for their quantitative and qualitative analyses. In general terms, for this purpose special voltage transformers have been used that, for being imported, are very expensive; furthermore there is no defined selection criterion that allows the voltage source to supply the current recommended by the IEC (International Electrotechnical Commission). In this article, a proposal is presented to select a transformer that fulfills the IEC requirements. This equipment, because of its acquisition easiness and economy, permits that any teaching or research institution have a voltage source that allows the experimentation of the pollution phenomena at a minimum cost. [Espanol] En la costa del Golfo de Mexico y en el noroeste del pais hay severos problemas de contaminacion en los aisladores de los sistemas electricos de distribucion. Para solucionar este problema, se reproducen, en laboratorios especializados, las condiciones de contaminacion para su analisis cualitativo y cuantitativo. En general, con este proposito se han utilizado transformadores especiales de voltaje que por ser de importacion son muy costosos; ademas, no existe un criterio definido de seleccion que permita suministrar a la fuente de voltaje la corriente recomendada por el IEC (International Electrotechnical Commission). En este articulo se presenta una propuesta para seleccionar un transformador que cumpla con los requerimientos del IEC. Esta, por su facilidad de adquisicion y economia, permite que cualquier institucion docente o de investigacion cuente con una fuente de voltaje que permita la experimentacion de los fenomenos contaminantes con un costo minimo.
Isolated PDM and PWM DC-AC SICAMs[Pulse Density Modulated; Pulse Width Modulated
Energy Technology Data Exchange (ETDEWEB)
Ljusev, P.
2004-03-15
In this report a class of isolated PDM and PWM DC-AC SICAMs is described, which introduce the audio reference only in the output stage. AC-DC power supply is implemented in its simplest form: diode rectifier followed by a medium-size charge-storage capacitor. Isolation from the AC mains is achieved using a high frequency (HF) transformer, receiving the HF voltage pulses from the input 'inverter' stage and transferring them to the output 'rectifier+inverter' stage, which can use either PDM or PWM. The latter stage is then interfaced to the load using an output low-pass filter. Each of the dedicated stages is discussed in detail. Measurements on the master/slave PWM DC-AC SICAM prototype are presented to help benchmarking the performance of this class of SICAMs and identify the advantages and drawbacks. (au)
Synchronization of the distributed PWM carrier waves for modular multilevel converters
DEFF Research Database (Denmark)
Burlacu, Paul Dan; Mathe, Laszlo
2014-01-01
The half-bridge modular multilevel converter has proven itself to be a suitable solution for HVDC application. In order to achieve high modularity and fault tolerance, distributed control strategy is one possible solution and is discussed in this paper. When distributed control strategy is used, there is a central controller and a local controller in each sub-module (SM). A problem appears when implementing the modulation using this type of control strategy; this is the lack of synchronization between the internal clocks of the different submodules controllers of the MMC. This will cause a drift between the PWM outputs of each sub-module increasing the total harmonic distortion of the output voltage. This paper presents a solution to synchronize the PWM outputs of the MMC submodules using EtherCAT communication protocol focusing on phase shifted PWM modulation technique.
EVALUATION OF VARIOUS UNIPOLAR MULTICARRIER PWM STRATEGIES FOR FIVE LEVEL FLYING CAPACITOR INVERTER
Directory of Open Access Journals (Sweden)
B. SHANTHI
2012-06-01
Full Text Available This paper presents the comparison of unipolar multicarrier Pulse Width Modulation (PWM techniques for the Flying Capacitor Multi Level Inverter (FCMLI. Due to switch combination redundancies, there are certain degrees of freedom to generate the five level AC output voltage. This paper presents the use of Control Freedom Degree (CFD combination. The effectiveness of the PWM strategies developed using CFD are demonstrated by simulation and experimentation. The results indicate that the multilevel inverter triggered by the developed USHPWM strategy exhibits reduced harmonics. PWM strategies developed are implemented in real time using dSPACE/Real Time Interface (RTI. The simulation and experimental output closely match with each other validating the strategies presented.
DEFF Research Database (Denmark)
Huang, Shaojun; Mathe, Laszlo
2013-01-01
Two existing methods to implement resampling modulation technique for modular multilevel converter (MMC) (the sampling frequency is a multiple of the carrier frequency) are: the software solution (using a microcontroller) and the hardware solution (using FPGA). The former has a certain level of inaccuracy in terms of switching instant, while the latter is inflexible with higher cost. In order to overcome these drawbacks, this paper proposes an alternative solution, which uses high frequency saw-tooth carrier and two independent comparators, usually available in microcontrollers, to create the proper switching instances needed for the resampling modulation technique. The software implementation of the proposed phase shifted PWM (PS-PWM) method, and its application in a distributed control system for MMC, are fully discussed in this paper. Simulation and experiment results show that the proposed solution can realize the resampled uniform PWM and provide high effective sampling frequency and low time delay, which is critical for the distributed control of MMC.
Compositional modeling of three-phase flow with gravity using higher-order finite element methods
Moortgat, Joachim
2011-05-11
A wide range of applications in subsurface flow involve water, a nonaqueous phase liquid (NAPL) or oil, and a gas phase, such as air or CO2. The numerical simulation of such processes is computationally challenging and requires accurate compositional modeling of three-phase flow in porous media. In this work, we simulate for the first time three-phase compositional flow using higher-order finite element methods. Gravity poses complications in modeling multiphase processes because it drives countercurrent flow among phases. To resolve this issue, we propose a new method for the upwinding of three-phase mobilities. Numerical examples, related to enhanced oil recovery and carbon sequestration, are presented to illustrate the capabilities of the proposed algorithm. We pay special attention to challenges associated with gravitational instabilities and take into account compressibility and various phase behavior effects, including swelling, viscosity changes, and vaporization. We find that the proposed higher-order method can capture sharp solution discontinuities, yielding accurate predictions of phase boundaries arising in computational three-phase flow. This work sets the stage for a broad extension of the higher-order methods for numerical simulation of three-phase flow for complex geometries and processes.
Elimination of output voltage oscillations in DC-DC converter using PWM with PI controller
Directory of Open Access Journals (Sweden)
Sreenivasappa Veeranna Bhupasandra
2010-01-01
Full Text Available In this paper the SIMULINK model of a PWM controlled DC-DC converter is modeled using switching function concept to control the speed of the DC motor. The presence of the voltage oscillation cycles due to higher switching frequency in the DC-DC converter is identified. The effect of these oscillations on the output voltage of the converter, Armature current, Developed torque and Speed of the DC motor is analyzed. In order to minimize the oscillation cycles the PI controller is proposed in the PWM controller.
Led spectral and power characteristics under hybrid PWM/AM dimming strategy
DEFF Research Database (Denmark)
Beczkowski, Szymon; Munk-Nielsen, Stig
2010-01-01
In order to dim LEDs the pulse width modulation (PWM) or amplitude modulation (AM) dimming scheme is typically used. Previous studies show that these dimming schemes can have opposite effects on diodes peak wavelength shift. An experimental study was conducted to test the behavior of InGaN diodes and phosphor-converted white diodes under hybrid PWM/AM modulation. Feed forward control schemes that provide stable peak wavelength position during dimming and the ability to compensate the thermally induced color shifts and the decrease of the luminous flux are investigated.
Synchronized PWM Scheme for Dual Inverter-Fed Drives with Zero Common-Mode Voltages
DEFF Research Database (Denmark)
Oleschuk, Valentin; Blaabjerg, Frede
2005-01-01
Abstract - Novel method of direct synchronized pulsewidth modulation is applied for control of a dual inverter-fed opened winding induction motor drive with zero common-mode voltages. New strategy and algorithms of synchronized PWM provide symmetry of the phase voltage of the system during the whole control range including the zone of overmodulation. Spectra of the phase voltage do not contain even harmonics and sub-harmonics (combined harmonics), which is especially important for the drive systems with increased power rating. Simulations gave the behaviour of dual inverter-fed system with the proposed synchronized PWM scheme.
Adaptive nonlinear control of single-phase to three-phase UPS system
Directory of Open Access Journals (Sweden)
Kissaoui M.
2014-01-01
Full Text Available This work deals with the problems of uninterruptible power supplies (UPS based on the single-phase to three-phase converters built in two stages: an input bridge rectifier and an output three phase inverter. The two blocks are joined by a continuous intermediate bus. The objective of control is threefold: i power factor correction “PFC”, ii generating a symmetrical three-phase system at the output even if the load is unknown, iii regulating the DC bus voltage. The synthesis of controllers has been reached by two nonlinear techniques that are the sliding mode and adaptive backstepping control. The performances of regulators have been validated by numerical simulation in MATLAB / SIMULINK.
Chaotic Recurrence Analysis of Oil-Gas-Water Three-phase Flow in Vertical Upward Pipe
Directory of Open Access Journals (Sweden)
Ling-Fu Kong
2011-01-01
Full Text Available In this study, the conductance fluctuating signals of oil/gas/water were analyzed by using nonlinear chaotic recurrence, were obtained four kinds of recurrence quantification indicator, recurrence rate, determinism, average length of diagonal segment, entropy which got the transition law of the oil/gas/water three-phase flow patterns in vertical upward pipe. Specific process was: Firstly the C-C algorithm was used to determine phase space embedding dimension and time delay of nonlinear time series, then the method of using the time series data generated by the Lorenz equation to verify the sensitivity of recurrence quantification analysis was presented, finally the chaotic recurrence analysis method was used to identify three-phase flow patterns. The results show that: the texture of chaotic recurrence plot can reflect the oil/gas/water three-phase flow pattern evolution, the recurrence quantification indicator with the phase flow are more sensitive.
Proposed Method for Shoot-Through in Three Phase ZSI and Comparison of Different Control Techniques
Directory of Open Access Journals (Sweden)
Byamakesh Nayak
2014-07-01
Full Text Available This paper presented the new methodology for different control techniques applied to three phase Z-source inverter for minimisation of switching losses. The procedure for proposed control techniques and its effects on the performance of operation of three phase Z-source inverter are analyzed. The graphs for voltage gain and voltage stress are drawn for different control methods. The flow-chart for the symmetrical and unsymmetrical control techniques for creating pulse signals for switches of three phase inverter are shown. All the methods are studied and compared with each other. The Total harmonic distortion (THD of output voltage of both the control methods has been analyzed using FFT analysis. The experiments done and the results shown for capacitor voltage, load current and load line voltage for simple boost and constant boost control techniques are presented using MATLAB/ Simulink.
AC Motor Drive Fed by Renewable Energy Sources with PWM
Directory of Open Access Journals (Sweden)
J. Pavalam
2014-01-01
Full Text Available In this fast aproaching nature of technology the ned of Electricity becomes a mandatory in developing technology. The ned of Electricity increases the power demand where the power demand met by the conventional sources of energy has some disadvantage of polution, this disadvantage can be decreased by the use of the Renewable energy sources like Fuel Cel and available solar energy. When a FUEL cel produces AC power, basicaly two stages are required for conversion first a bosting stage and second is inversion stage. In this paper the Bost inverter topology is achieved where in the conventional methods the normal DC - AC power conversion method is used where as in this paper the PWM based DC - AC inverter has ben used which is useful in reducing the harmonics in the output of the Inverter. The voltage controled output is produced in the bost inverter the curent controled output is taken from dc-dc bidirectional converter. The Fuel cel canot be relied as a whole so a Solar PV module is conected acros the Load so while the Sunlight days the PV arays generate power and in the night time the Fuel cel is used to generate power for the load. Since, the Fuel cel and PV arays can generate power in Partial load they are prefered than any other sources. When the output from the Solar PV aray is low or when the sunlight available is not eficient in generating the power a automatic switch over is provided in the junction betwen the Solar PV aray and Fuel cel so that whenever it hapens the switch automaticaly switch over to another source. The simulation results are presented to confirm the operational feature of the proposed system.
Imaging phase holdup distribution of three phase flow systems using dual source gamma ray tomography
International Nuclear Information System (INIS)
Full text: Multiphase reaction and process systems are used in abundance in the chemical and biochemical industry. Tomography has been successfully employed to visualize the hydrodynamics of multiphase systems. Most of the tomography methods (gamma ray, x-ray and electrical capacitance and resistance) have been successfully implemented for two phase dynamic systems. However, a significant number of chemical and biochemical systems consists of dynamic three phases. Research effort directed towards the development of tomography techniques to image such dynamic system has met with partial successes for specific systems with applicability to limited operating conditions. A dual source tomography scanner has been developed that uses the 661 keV and 1332 keV photo peaks from the 137Cs and 60Co for imaging three phase systems. A new approach has been developed and applied that uses the polyenergetic Alternating Minimization (A-M) algorithm, developed by O'Sullivan and Benac (2007), for imaging the holdup distribution in three phases' dynamic systems. The new approach avoids the traditional post image processing approach used to determine the holdup distribution where the attenuation images of the mixed flow obtained from gamma ray photons of two different energies are used to determine the holdup of three phases. In this approach the holdup images are directly reconstructed from the gamma ray transmission data. The dual source gamma ray tomography scanner and the algorithm were validated using a three phase phantom. Based in the validation, three phase holdup studies we carried out in slurry bubble column containing gas liquid and solid phases in a dynamic state using the dual energy gamma ray tomography. The key results of the holdup distribution studies in the slurry bubble column along with the validation of the dual source gamma ray tomography system would be presented and discussed
Field results on developed three-phase four-wire shunt active power filters
Pinto, J. G.; Neves, Pedro; Gonçalves, Domingos; Joăo L Afonso
2009-01-01
Abstract-This paper presents three-phase four-wire Shunt Active Power Filters with ability to compensate current harmonics, power factor, and current unbalance. The power stage of the Active Power Filters is based on a two-level four-leg inverter. The switching technique is based on an optimized periodic sampling strategy, and the digital controller uses the Theory of Instantaneous Reactive Power (p-q Theory) expanded for three- phase four-wire systems. The presented Active Power Filters were...
Area Based Approach for Three Phase Power Quality Assessment in Clarke Plane
Directory of Open Access Journals (Sweden)
S. CHATTOPADHYAY
2008-03-01
Full Text Available This paper presents an area-based approach for electric power quality analysis. Some specific reference signals have been defined and areas formed by the real power system data with the reference signal have been calculated wherefrom contributions of fundamental waveform and harmonic components have been assessed separately. Active power, reactive power and total harmonic distortion factors have been measured. Clarke transformation technique has been used for analysis in three-phase system, which has reduced the computational effort to a great extent. Distortion factors of individual phase of a three-phase system have also been assessed.
Three-Phase Modulated Pole Machine Topologies Utilizing Mutual Flux Paths
DEFF Research Database (Denmark)
Washington, Jamie G.; Atkinson, Glynn J.
2012-01-01
This paper discusses three-phase topologies for modulated pole machines (MPMs). The authors introduce a new threephase topology, which takes advantage of mutual flux paths; this is analyzed using 3-D finite-element methods and compared to a three-phase topology using three single-phase units stacked axially. The results show that the new “combined-phase MPM” exhibits a greater torque density, while offering a reduction in the number of components. The results obtained from two prototypes are also presented to verify the concept; the results show that the “combined-phase” machine could provide both performance and constructional benefits over prior MPM topologies.
THRIVE : a data reduction program for three-phase PDV/PDI and VISAR measurements.
Energy Technology Data Exchange (ETDEWEB)
Jones, Scott Christopher; Dolan, Daniel H.
2008-06-01
THRIVE (THRee Interferometer VElocimetry) is an analysis package for reducing three-phase interferometry measurements. Three-phase displacement interferometry measurements are the primary application of this program, although velocity interferometry is also supported. THRIVE uses a push-pull approach to transform measured signals to a pair of quadrature signals, from which fringe shift, target position, and target velocity are inferred. The program can analyze the signals in an ideal sense or compensate for non-ideal measurement conditions using ellipse characterization. The program can be run in any current version of MATLAB (release 2007a or later) or as a Windows XP executable.
Performance Evaluation of an Extended Gain Three-Phase Grid Connected Boost-inverter
DR. A.ELSEROUGI; DR. A.S.ABDEL-KHALIK; DR. A.MASSOUD; DR. S.AHMED
2013-01-01
Three-phase boost-inverter consists of three DC-to-DC boost converters with a common point and operates with boosting capability to feed three-phase star connected Load. The main advantage of that inverter is the use of only six IGBTs andsmall passive elements to obtain an AC output larger than the DC input. This inverter can amplify power sources such as fuelcells, small turbines, and photovoltaic arrays (i.e. it is suitable for distributed power applications). In this paper, two main contri...
An alternative for reducing the layers in the construction of three-phase planar transformers
Prieto López, Roberto; Asensi Orosa, Rafael; García Suárez, Oscar; Cobos Márquez, José Antonio; Jerez, F.; Flavio David, Gerez
2012-01-01
A modified winding layout for three-phase transformers with PCB windings is proposed in this paper. This modified layout can be used in high current transformers with many PCB layers to simplify the fabrication process. One of the key factors that might increase the cost and complexity in the construction of planar transformers is the number of layers of each PCB winding. This issue becomes even more important in medium-high power three-phase transformers, where the number of PCB layers is hi...
Existence of three-phase interlines on a cerium dioxide surface
Osarinmwian, Charles
2013-01-01
The three-phase interline described by a statistical continuum limit (i.e. quasi-boundary) has been postulated to gain a deeper insight into the reduction of CeO2 to CeO1.940 in a LiCl-KCl eutectic melt. Fabrication of a CeO2 superstructure by a condensed-phase method provided a CeO2 (111) surface at the nanoscale, which allowed the three-phase interline to be identified given previously reported quantum confinement effects in quasi-stoichiometric CeO2 nanoparticles. Also, t...
Surface Effect on Three Phase Lines of Low-Ohmic Furnaces
Directory of Open Access Journals (Sweden)
Pavel Novak
2004-01-01
Full Text Available The article another option of using numerical method of elementary conductors in surface effect three-phase supply linesfor low-ohmic furnaces. Impedance asymmetry of three-phase supply lines of different conductor profiles and various spaceconfigurations is analysed following to the author`s article published in this journal (Vol. 2/2003, No. 2, pg. 42. Options of reducingunfavourable effect of so called live and dead phase and their utilization in design and construction of mentioned lines are outlined.
Three-phase scintigraphy in epicondylitis of the lateral lower humerus
Energy Technology Data Exchange (ETDEWEB)
Koppers, B.; Riel, K.
1982-08-01
Ten patients with tennis elbow were examined by three-phase scintigraphy, using sup(99m)Tc-MDP. In agreement with the histological findings of H. Schneider (14), there was no uptake during the perfusion and soft tissue phase. In the phase, there was focal bone uptake in one patient only.
Three-phase diode rectifiers with low harmonics current injection methods
Pejovic, Predrag
2007-01-01
Presents results of numerous research papers in the area of current injection based rectifiers. This book discusses the principles of current injection, followed by an analysis of various magnetic current injection devices. It concludes with a chapter where the results are generalized to three-phase full-bridge thyristor rectifiers.
A predictive control algorithm for an active three-phase power filter
Directory of Open Access Journals (Sweden)
R.V. Vlasenko
2014-09-01
Full Text Available The paper deals with grid connection circuits for active filters, structures of active power filter control systems, and methods based on full capacity components determination. The existing structures of active power filter control and control algorithm adjustment for valve commutation loss reduction are analyzed. A predictive control algorithm for an active three-phase power filter is introduced.
Directory of Open Access Journals (Sweden)
Angelo A. Beltran Jr
2014-04-01
Full Text Available Sinusoidal pulse width modulation is a popular modulation for most alternating current induction motor. It only requires fewer calculations and is easy to implement. However, the shortcomings of using it are low DC voltage utilization, and poor inverter transmission capability. In recent years, there is an increasing trend and more research concentration of using space vector pulse width modulation in adjustable speed drives and renewable energy systems because it has better DC bus utilization, better performance, lower loss, lower ripples, and wide application range. This paper introduces space vector pulse width modulation and applies to speed control of alternating current induction motor. The three phase alternating current induction motor is reviewed based upon space vector representation. The development of space vector pulse width modulation and implementation to speed control of induction motor is done using Matlab/Simulink. The simulation is conducted by analyzing the response of stator current, stator voltage, speed, voltage, frequency, and the electromagnetic torque. Simulation results shows that space vector pulse width modulation which generates the voltage patterns at real time is able to control the speed of a three phase alternating current induction motor. It indicates the validity of space vector pulse width modulation in controlling the speed of a three phase alternating current induction motor (ACIM. In conclusion, the use and realization of space vector pulse width modulation has been validated by the Matlab/Simulink simulation experiment for controlling the speed of a three phase alternating current induction motor.
Teaching Qualitative Research for Human Services Students: A Three-Phase Model
Goussinsky, Ruhama; Reshef, Arie; Yanay-Ventura, Galit; Yassour-Borochowitz, Dalit
2011-01-01
Qualitative research is an inherent part of the human services profession, since it emphasizes the great and multifaceted complexity characterizing human experience and the sociocultural context in which humans act. In the department of human services at Emek Yezreel College, Israel, we have developed a three-phase model to ensure a relatively…
Active and reactive power control of a current-source PWM-rectifier using space vectors
Energy Technology Data Exchange (ETDEWEB)
Salo, M.; Tuusa, H. [Tampere University of Technology (Finland). Department of Electrical Engineering, Power Electronics
1997-12-31
In this paper the current-source PWM-rectifier with active and reactive power control is presented. The control system is realized using space vector methods. Also, compensation of the reactive power drawn by the line filter is discussed. Some simulation results are shown. (orig.) 8 refs.
Performance analysis of SHE-PWM using Fourier Series and Newton-Raphson analysis
Lada, M. Y.; Khiar, M. S. A.; Ghani, S. A.; Nawawi, M. R. M.; Nor, A. S. M.; Yuen, J. G. M.
2015-05-01
The performance of inverter has become a vital role in contributing effective power system nowadays. However the major issue that will reduce the inverter performance is the harmonic distortions that contribute to power losses. Thus, there are a variety of controls techniques have been implemented for inverters switching such as square wave, SHE-PWM, unipolar and bipolar. The square wave type inverter produces output voltage in square shape which has simple logic control and power switches. Next, unipolar and bipolar techniques are using comparator to compare the reference voltage waveform with the triangular waveform. The difference between unipolar and bipolar is there are two reference signals which are compared with the triangular waveform for unipolar switching. On the other hand, bipolar switching compares triangular waveform with a reference signal. Selective Harmonic Elimination Pulse-Width Modulation (SHE-PWM) is another control technique for inverters. This research propose SHE-PWM as a low switching frequency strategy that uses Fourier Series and Newton-Raphson analysis to calculate the switching angles for elimination of harmonic distortion. Fourier Series is used to determine the amplitude of any odd harmonic in the output signal whereas Newton-Raphson is used to solve the equation for finding switching angles. As a result, SHE-PWM can select the low frequency harmonic components need to be eliminated and reduce the harmonic distortion. It also prevents the harmonic distortion that sensitive to the inverter performance
Analytical Modelling of Periodical PWM Converter Fed R-L Load.
Czech Academy of Sciences Publication Activity Database
Klíma, J.; Schreier, Lud?k
Orlando, Florida : International Institute of Informatics and Systemics, 2003, s. 406-411. ISBN 980-6560-01-9. [World Multiconference on Systemics, Cybernetics and Informatics - SCI 2003 /7./. Orlando, Florida (US), 27.07.2003-30.07.2003] Institutional research plan: CEZ:AV0Z2057903 Keywords : analytical model * periodical PWM * Laplace transform Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Sensorless Position Measurement Based on PWM Eddy Current Variation for Switched Reluctance Motor
Laurent, Philippe; Multon, Bernard; Hoang, Emmanuel; Gabsi, Mohamed
1994-01-01
This paper proposes a new method for indirect sensing of the rotor position in a switched reluctance motor. The method operates with the rotor eddy current losses produced by the PWM converter switching, regardless of magnetic saturation. Experimental results concerning sensivity and performances are schown in a 6/4 30W 3000rpm SRM.
CFD modeling of three-phase bubble column: 1. Study of flow pattern
Energy Technology Data Exchange (ETDEWEB)
M. Anil; V.K. Agarwal; M. Siraj Alam [Indian Institute of Technology, Roorkee (India). Chemical Engineering Department; K.L. Wasewar [Indian Institute of Technology, Roorkee (India). Chemical Engineering Department]. k_wasewar@rediffmail.com
2007-09-15
Bubble column (BC) or slurry bubble column (SBC) reactor has emerged as one of the most promising devices in chemical, biochemical and environmental engineering operations because of its simple construction, isothermal conditions, high heat and mass transfer rates, and on-line catalyst addition and withdrawal. Applications include absorption, catalytic slurry reactions, bioreactions and coal liquefaction. The present work has been carried out to characterize the dynamics of three-phase flow in cylindrical bubble column, run under homogeneous bubble flow and heterogeneous flow conditions using CFD (Computational Fluid Dynamics) simulation. The investigation has been done to study the flow pattern of three-phase bubble column along with parametric studies. The simulations were performed for air-water-glass beads in a bubble column of 0.6m height, 0.1m i.d. and 0.05m sparger diameter to study the flow pattern. Eulerian-Eulerian three-phase simulations with {kappa}-{epsilon} turbulence for liquid phase were carried out using the commercial flow simulation software CFX-5.6, with a focus on characterizing the dynamics properties of gas liquid solid flows. The model has been validated using available experimental data and is in good agreement. Detail study of the flow pattern in three-phase bubble column has been carried out and flow pattern has been presented in the form of contour and vector plots. The results presented are useful for understanding the dynamics of gas liquid solid flows in bubble column and provide a basis for further development of CFD model for three phase systems.
Directory of Open Access Journals (Sweden)
Bharati Raja
2012-12-01
Full Text Available This work presents the comparative study of the different PWM techniques to reduce the common-mode voltage (CMV at the output of neutral point diode clamped inverter for variable speed drives. Here the comparative study is done by the phase opposition disposed (POD, sinusoidal pulse width modulation (SPWM, phase disposition (PD, phase shift (PS space vector modulation (SVM techniques are proposed. A good trade-off between the quality of the output voltage and the partial magnitude of the CMV is achieved in this work. The scheme is proposed for three-level inverter. This work realizes the implementation of Three-level diode clamped MLI for three-phase (Y-? induction motor with the implementation of a space vector modulation technique without any additional control algorithm to reduce CMV within the range + Vdc/6. The Simulation with a 1HP induction motor drive system is setup in Matlab-2011b and the same results validated effectively by hardware – FPGA-SPARTEN III processor and its shows that the CM voltage is effectively reduced and the maximum output voltage is not affected.
Calderone, Luigi; Pinola, Licia; Varoli, Vincenzo
1992-04-01
The paper describes an analytical procedure to optimize the feed-forward compensation for any PWM dc/dc converters. The aims of achieving zero dc audiosusceptibility was found to be possible for the buck, buck-boost, Cuk, and SEPIC cells; for the boost converter, however, only nonoptimal compensation is feasible. Rules for the design of PWM controllers and procedures for the evaluation of the hardware-introduced errors are discussed. A PWM controller implementing the optimal feed-forward compensation for buck-boost, Cuk, and SEPIC cells is described and fully experimentally characterized.
Mohammad Sarvi, Iman Soltani; Hossein Faramarzi
2013-01-01
In this paper has used positive, negative and combined switching strategies for three phase ac/ac matrix converter.the author compares these strategies. The performance comparison of these three strategies is made under balanced operation. The simulation of three phase matrix converter feeding a three phase load was accomplished by means of the matlab/simulink software. After the simulation the comparison of the waveforms THD in three switching sequence is done. It must be mentioned that the ...
International Nuclear Information System (INIS)
The improvement capacity of Cockcroft-Walton high voltage source from 300 kV/20 mA to 500 kV/mA has been carrying out. To improve the capacity of high voltage source was done by means of increasing the stage number of voltage multiplier from 11 to 18 and its output voltage measuring resistance. Each stage of voltage multiplier consists of 2 capacitors and 2 circuits of high voltage diode. This voltage multiplier is constructed using main components of high voltage capacitor and high voltage diode each of 0.22 ?F/50 kV and UF 5408 respectively. To avoid stray discharge and corona it was provided with high voltage electrode and corona ring. The test result indicated that the output voltage obtained from 16 stages was 350 kV according to operating condition of 25 M? resistive load and first stage voltage of 28.5 kV with oscillator frequency of 24 Hz. That condition requires anode voltage and current of 5.5 kV and 2.5 A respectively. The no load test for 16 stages indicates 400 kV of output voltage and 28.5 kV first stage voltage. Efficiency of high voltage source was 48 % at 6.75 kW of output power. The expected test of 500 kV with 18 stages of voltage multiplier can not be carried out because of some restrictive of loading system. From the test result can be predicted that the output voltage of 500 kV with 18 stages of voltage multiplier requires 31.2 kV of first stage voltage. Then the expected high voltage source of Cockcroft-Walton is capable as accelerating voltage source for Electron Beam Machine with energy of 500 kV. (author)
Dynamic\tmodelling of catalytic three-phase reactors for hydrogenation and oxidation processes
Directory of Open Access Journals (Sweden)
T. Salmi
2000-12-01
Full Text Available The dynamic modelling principles for typical catalytic three-phase reactors, batch autoclaves and fixed (trickle beds were described. The models consist of balance equations for the catalyst particles as well as for the bulk phases of gas and liquid. Rate equations, transport models and mass balances were coupled to generalized heterogeneous models which were solved with respect to time and space with algorithms suitable for stiff differential equations. The aspects of numerical solution strategies were discussed and the procedure was illustrated with three case studies: hydrogenation of aromatics, hydrogenation of aldehydes and oxidation of ferrosulphate. The case studies revealed the importance of mass transfer resistance inside the catalyst pallets as well as the dynamics of the different phases being present in the reactor. Reliable three-phase reactor simulation and scale-up should be based on dynamic heterogeneous models.
Dynamic modelling of catalytic three-phase reactors for hydrogenation and oxidation processes
Scientific Electronic Library Online (English)
T., Salmi; J., Wärnĺ; S., Toppinen; M., Rönnholm; J.P., Mikkola.
2000-12-01
Full Text Available The dynamic modelling principles for typical catalytic three-phase reactors, batch autoclaves and fixed (trickle) beds were described. The models consist of balance equations for the catalyst particles as well as for the bulk phases of gas and liquid. Rate equations, transport models and mass balanc [...] es were coupled to generalized heterogeneous models which were solved with respect to time and space with algorithms suitable for stiff differential equations. The aspects of numerical solution strategies were discussed and the procedure was illustrated with three case studies: hydrogenation of aromatics, hydrogenation of aldehydes and oxidation of ferrosulphate. The case studies revealed the importance of mass transfer resistance inside the catalyst pallets as well as the dynamics of the different phases being present in the reactor. Reliable three-phase reactor simulation and scale-up should be based on dynamic heterogeneous models.
Voltage unbalance mitigation in LV networks using three-phase PV systems
DEFF Research Database (Denmark)
Garcia Bajo, Cristina; Hashemi, Seyedmostafa
2015-01-01
In this paper a new method is proposed to mitigate voltage unbalance caused by single-phase solar inverters in low voltage (LV) networks. The method is based on uneven reactive power absorption and injection by three-phase solar inverters. Independent control of each phase is performed to achieve this uneven injection. The average values of phase voltages at the connection points of the photovoltaic (PV) inverters are used as the references for the balancing algorithm. Voltage unbalance mitigation is achieved by use of this method in different scenarios with variable three-phase and single-phase inverters penetration in a realistic LV grid. In addition, the overvoltage is reduced by using this method.
International Nuclear Information System (INIS)
Combination of ultrasonic nebulizer and plasma excitation sources for spectrochemical analysis offers desirable features of low detection limits, high sample through out, wide dynamic range of operation, acceptable precision and accuracy, and simultaneous quantitative analytic capabilities. Moreover, the ultrasonic nebulizer does not require sample preconcentration. Recently we have developed a three phase plasma arc (TPPA) for atomic emission spectrochemical analysis. In the present work, to increase the analytical utility of the three-phase plasma system, ultrasonic nebulizer was used for sample introduction. The effects of the argon gas flow rate, current, excitation temperature have been studied. The analytical calibration curves are obtained for Ca, Cr, Fe, Mg and Mn and detection limits have been calculated. The present technique is used to determine the concentration of elements the Ca, Cr, Fe, Mg and Mn in airborne samples
Ghatass, Z. F.; Roston, G. D.; Mohamed, M. M.
2002-12-01
Combination of ultrasonic nebulizer and plasma excitation sources for spectrochemical analysis offers desirable features of low detection limits, high sample through out, wide dynamic range of operation, acceptable precision and accuracy, and simultaneous quantitative analytic capabilities. Moreover, the ultrasonic nebulizer does not require sample preconcentration. Recently we have developed a three phase plasma arc (TPPA) for atomic emission spectrochemical analysis. In the present work, to increase the analytical utility of the three-phase plasma system, ultrasonic nebulizer was used for sample introduction. The effects of the argon gas flow rate, current, excitation temperature have been studied. The analytical calibration curves are obtained for Ca, Cr, Fe, Mg and Mn and detection limits have been calculated. The present technique is used to determine the concentration of elements the Ca, Cr, Fe, Mg and Mn in airborne samples.
Implementation of Single Phase Hybrid Active Power Filter for Single & Three Phase Systems
Directory of Open Access Journals (Sweden)
V. OBUL REDDY, POOJARI VIDYA SAGAR
2013-08-01
Full Text Available Abstract:This paper presents an implementation of hybrid active power filter for decreasing the distortions in currents in a single-phase and three phase systems. In this method, the active power filter is injecting equal but opposite current to mitigate the distortion current shape the supply current to a sinusoidal form and in phase with the supply voltage. To reduce switching stress, losses a single-switch parallel active power filter is used. for removing the high order and low order harmonics a parallel active power filter and a passive filter is connected. The passive filter uses simple LC configuration; while the parallel active filter uses a single- switch topology typically used in boost rectifier circuit. Theoretical, simulation results are presented for the single and three-phase systems with feeding non-linear loads.
Estimation of Harmonics in Three-Phase and Six-Phase Load Circuits
Directory of Open Access Journals (Sweden)
Deepak Kumar
2014-10-01
Full Text Available The Harmonics are very harmful within an electrical system and can have serious consequences such as reducing the life of apparatus, stress on cable and equipment etc. This paper cites extensive analytical study of harmonic characteristics of multiphase (six- phase and three-phase system equipped with two & three level inverters for non-linear loads. Multilevel inverter has elevated voltage capability with voltage limited devices; low harmonic distortion; abridged switching losses. Multiphase technology also pays a promising role in harmonic reduction. Matlab simulation is carried out to compare the advantage of multi-phase over three phase systems equipped with two or three level inverters for non-linear load harmonic reduction.The extensive simulation results are presented based on case studies.
Simulation of a three-phase three-dimensional reacting flow in an FCC industrial riser
Energy Technology Data Exchange (ETDEWEB)
Lopes, Gabriela Cantarelli; Rosa, Leonardo Machado da; Mori, Milton; Nunhez, Jose Roberto [Universidade Estadual de Campinas (FEQ/UNICAMP), SP (Brazil). Fac. de Engenharia Quimica], E-mails: gacleq@feq.unicamp.br, mori@feq.unicamp.br, leorosa@feq.unicamp.br, nunhez@feq.unicamp.br; Martignoni, Waldir Pedro [PETROBRAS, Rio de Janeiro, RJ (Brazil). Gerencia de Otimizacao], E-mail: martignoni@petrobras.com.br
2011-04-15
This study used a three-dimensional and three-phase flow model to predict the dynamic behavior of a fluid catalytic cracking (FCC) industrial reactor. It took into account heat transfer, feedstock vaporization and cracking reactions. The Eulerian/Eulerian-Lagrangian approach was used to simulate the dynamic three-phase flow inside the riser. The catalytic cracking reactions were predicted using the 4-lump model. A commercial CFD code (Fluent) was used to obtain the numerical data, and appropriate user defined functions were implemented to model the heterogeneous kinetics and the catalyst deactivation. Results show nonuniform tendencies inside the reactor, emphasizing the importance of a sophisticated model in FCC process predictions. (author)
Modeling and control of three phase rectifier with electronic smoothing inductor
DEFF Research Database (Denmark)
Singh, Yash Veer; Rasmussen, Peter Omand
2011-01-01
This paper presents a simple, direct method for deriving the approximate, small-signal, average model and control strategy for three-phase diode bridge rectifier operating with electronic smoothing technique. Electronic smoothing inductor (ESI) performs the function of an inductor that has controlled variable impedance. This increases power factor (PF) and reduces total harmonic distortions (THDs) in mains current. The ESI based rectifier enables compact and cost effective design of three phase electric drive as size of passive components is reduced significantly. In order to carry out stability and voltage regulation studies, the average, small-signal, dynamic model and control strategy of the ESI is developed and validated by simulation and laboratory measurements.
Performance Evaluation of an Extended Gain Three-Phase Grid Connected Boost-inverter
Directory of Open Access Journals (Sweden)
DR. A.ELSEROUGI
2013-05-01
Full Text Available Three-phase boost-inverter consists of three DC-to-DC boost converters with a common point and operates with boosting capability to feed three-phase star connected Load. The main advantage of that inverter is the use of only six IGBTs andsmall passive elements to obtain an AC output larger than the DC input. This inverter can amplify power sources such as fuelcells, small turbines, and photovoltaic arrays (i.e. it is suitable for distributed power applications. In this paper, two main contributions are presented; first is applying the third harmonic injection scheme to increase the boost-inverter gain. This method permits 15% increase in the output voltage without causing any distortion to line-to-line voltages. Second one studying performance of the grid connected boost-inverter. Simulation and experimental results show the effectiveness of that inverter in grid connection applications.
Transient analysis of three-phase induction machine using different reference frames
Directory of Open Access Journals (Sweden)
Vivek Pahwa
2009-10-01
Full Text Available Three-phase induction machines are generally used as motors for many industrial applications and all this is due to its simple construction and other advantages in contrast to other machines. Popularity of these motors has resulted into a lot of research including the transient behavior of the machine. Literature survey reveals that most of the researchers adopted only a single reference frame to estimate transient behavior of the machine. In this paper qd axis based modeling is proposed to analyze the transient performance of three-phase squirrel cage induction motor using stationary reference frame, rotor reference frame and synchronously rotating reference frame. Simulated results have been compared and verified with experimental results on a test machine. A close agreement between the simulated and experimental results proves the validity of proposed modeling. The proposed system has been developed using MATLAB/SIMULINK.
You, Hong; Luo, Wei-nan; Yao, Jie; Chen, Ping; Cai, Wei-min
2005-01-01
A novel three-phase internal circulating fluidized bed photocatalytic reactor was established and the radiation transformation in which was investigated. The experimental results indicate that with the interaction of gas and solid (gas flux > 0.3m3/h), the radiation transformation in the reactor along radial direction conforms to a definite exponential function, which agrees to formula Rose about the rules of light intensity distribution through evenly suspended particles. The value of radiation energy is affected by the initial light intensity, the concentration of photocatalyst and the thickness of liquid layer. The aerated gas amount only influence the state of the fluidized bed and has little effect on the distribution of light intensity along radical direction. Photocatalytic degradation of Rhodamine B indicate that the efficiency of three-phase internal circulating fluidized bed is much higher than slurry bed. The optimal catalyst concentration of this system is 10 - 12g/L. PMID:15859420
Leakage Current Elimination of Four-Leg Inverter for Transformerless Three-Phase PV Systems
DEFF Research Database (Denmark)
Guo, Xiaoqiang; He, Ran
2015-01-01
Eliminating the leakage current is one of the most important issues for transformerless three phase photovoltaic (PV) systems. In this paper, the leakage current elimination of a three-phase four-leg PV inverter is investigated. With the common mode loop model established, the generation mechanism of the leakage current is clearly identified. Different typical carrier-based modulation methods and their corresponding common mode voltages are discussed. A new modulation strategy with Boolean logic function is proposed to achieve the constant common mode voltage for the leakage current reduction. Finally the different modulation methods are implemented and tested on the TMS320F28335 DSP +XC3S400 FPGA digital control platform. The experimental results verify the effectiveness of the proposed solution.
A Smart Current Modulation Scheme for Harmonic Reduction in Three- Phase Motor Drive Applications
DEFF Research Database (Denmark)
Davari, Pooya; Zare, Firuz
2015-01-01
Electric motor-driven systems consume considerable amount of the global electricity. Majority of three-phase motor drives are equipped with conventional diode rectifier and passive harmonic mitigation, being witnessed as the main source in generating input current harmonics. While many active harmonic mitigation methods have been developed over the years, the total cost and complexity has become the main obstacle in employing prior-art methods for motor drive systems. This paper presents a novel current modulation method based on the electronic inductor concept for three-phase ac-dc systems to reduce input current harmonics. The obtained results at simulation and experimental levels confirm the effectiveness of the proposed approach.
Existence of three-phase interlines on a cerium dioxide surface
Osarinmwian, Charles
2013-01-01
The three-phase interline described by a statistical continuum limit (i.e. quasi-boundary) has been postulated to gain a deeper insight into the reduction of CeO2 to CeO1.940 in a LiCl-KCl eutectic melt. Fabrication of a CeO2 superstructure by a condensed-phase method provided a CeO2 (111) surface at the nanoscale, which allowed the three-phase interline to be identified given previously reported quantum confinement effects in quasi-stoichiometric CeO2 nanoparticles. Also, the CeO2 superstructure displays the same crystal lattice planes as a bulk CeO2 grain but the triply degenerate Raman-active peak of the grain is higher by a factor of ~ 2.5 with a wider full width at half maximum.
A novel process for extraction of edible oils. Enzyme assisted three phase partitioning (EATPP)
Energy Technology Data Exchange (ETDEWEB)
Gaur, R.; Sharma, A.; Khare, S.K.; Gupta, M.N. [Indian Institute of Technology, New Delhi (India). Chemistry Department
2007-02-15
Three phase partitioning (TPP), a technique used in protein purification has been evaluated, for extraction of oil from three different plant sources viz: mango kernel, soybean and rice bran. The process consists of simultaneous addition of t-butanol (1:1, v/v) and ammonium sulphate (w/v) to a crude preparation/slurry. Under optimized condition, the protein appears as an interfacial precipitate between upper t-butanol containing oil and lower aqueous phase. Pretreatment of the slurries with a commercial enzyme preparation of proteases, Protizyme {sup TM}, followed by three phase partitioning resulted in 98%, 86% and 79% (w/w) oil yields in case of soybean, rice bran and mango kernel, respectively. The efficiency of the present technique is comparable to solvent extraction with an added advantage of being less time consuming and using t-butanol which is a safer solvent as compared to n-hexane used in conventional oil extraction process. (author)
Secondary Voltage Unbalance Compensation for Three-Phase Four-Wire Islanded Microgrids
Tang, Fen; Zhou, Xiao; Meng, Lexuan; Guerrero, Josep M.; Vasquez, Juan Carlos
2014-01-01
This paper proposes a secondary voltage unbalance control approach that compensate voltage unbalances in three-phase four-wire islanded microgrid systems. It is implemented in the secondary control level of the microgrid hierarchical control structure. By sending information through low-bandwidth communication links to the primary control level, the required unbalanced factors at sensitive buses are achieved. Also, negative and zero sequence equivalent circuits and unbalance compensation prin...
Four-branch Star Hybrid Power Filter for Three-phase Four-wire Systems
Blaabjerg, Frede; Teodorescu, Remus; Rodriguez, Pedro; Candela, Ignacio; Luna, Alvaro
2008-01-01
This paper presents a new concept for filtering current harmonics in three-phase four-wire networks. The four-branch star (FBS) filtering topology presented in this work is characterized by a particular layout consisting of single-phase inductances and capacitors. Via this layout, a power filter, with two different and simultaneous resonance frequencies and sequences, is achieved -one frequency for positive-/negative- sequence and another one for zero-sequence components. This filter topology...
Performance Comparison of Three-Phase Shunt Active Power Filter Algorithms
Moleykutty George; Kartik P. Basu
2008-01-01
The usage of parallel converters is ever increasing. However, the voltage and current harmonics, zero-sequence and negative- sequence components of voltage and current and reactive power present in parallel converters give an alarming signal to power system and power electronic engineers. This research discusses performance of three-phase shunt active power filter (APF) system using three different control techniques namely synchronous detection algorithm (SDM), instantaneous active and react...
Raghava, Smita; Barua, Bipasha; Singh, Pradeep K.; Das, Mili; Madan, Lalima; Bhattacharyya, Sanchari; Bajaj, Kanika; Gopal, B; Varadarajan, Raghavan; Gupta, Munishwar N.
2008-01-01
Many recombinant eukaryotic proteins tend to form insoluble aggregates called inclusion bodies, especially when expressed in Escherichia coli. We report the first application of the technique of three-phase partitioning (TPP) to obtain correctly refolded active proteins from solubilized inclusion bodies. TPP was used for refolding 12 different proteins overexpressed in E. coli. In each case, the protein refolded by TPP gave either higher refolding yield than the earlier reported method or suc...
B.S.V.S.R. Krishna
2012-01-01
Fluidization is an operation in which solid particles are kept under suspension supported by the upward flow of liquid/gas phase. In classic fluidization the solids density are higher than the liquid, where as in Inverse fluidization the solids density are lower than that of continuous liquid phase. The phase holdup measurements in three phase classic/inverse fluidized beds are very important and difficult to measure. The phase holdups can be estimated with the help of pressure drop data and ...
Three phase four wire shunt active power filter from theory to industrial facility tests
Exposto, Bruno; Gonçalves, Henrique; Pinto, J. G.; Joăo L Afonso; Couto, Carlos
2011-01-01
Non-linear loads are very common in present industrial facilities, office buildings and even in our homes. This loads present several Power Quality problems to the electrical grid. The conventional solutions do not solve these problems in a suitable way. Therefore, it is necessary to find new solutions such as Active Power Filters. This paper presents and discusses the main steps that are necessary to implement a Three Phase Four Wire Shunt Active Power Filte...
Comparison of single and three-phase permanent magnet motor drives
Santander, Eduardo; Ben Ahmed, Hamid; Multon, Bernard; Soulard, Juliette; Rakotovao, M.; Barrere, Franck
1998-01-01
This article presents a comparison between two PM synchronous electrical motors of 0?5kW, a single phase machine and a three-phase machine designed for automotive applications. The single-phase structure developed by our laboratory displays the particularity of being completely symmetric: no mechanical or electromagnetic asymmetry. This machine starts with the maximum electromagnetic instantaneous torque and thus the corresponding current at the moment of start-up is very low. Both single and...
Controlling a Four-Quadrant Brushless Three-Phase dc Motor
Nola, F. J.
1986-01-01
Control circuit commutates windings of brushless, three-phase, permanent-magnet motor operating from power supply. With single analog command voltage, controller makes motor accelerate, drive steadily, or brake regeneratively, in clockwise or counterclockwise direction. Controller well suited for use with energy-storage flywheels, actuators for aircraft-control surfaces, cranes, industrial robots, and other electromechanical systems requiring bidirectional control or sudden stopping and reversal.
Comparative Study of Controller Design for Four Quadrant Operation of Three Phase BLDC Motor
Ms.K.Suganya*1
2014-01-01
Brushless DC motor drives are becoming more popular in industrial and traction applications. The control of BLDC motor in four quadrants is very vital. The three-phase permanent magnet brushless dc motor inherently needs an electronic commutation circuit to drive it, because it is not a self-commutating motor. It is contrary to the conventional brush motor which commutates itself. This paper presents a comparison study of three type of control such as PI, PID & fuzzy. The char...
Instantaneous Active and Reactive Power Measuring Method in Three Phase Power System
A. TAHRI; Azeddine DRAOU
2005-01-01
This paper describes an electronic means of measuring the instantaneous active and reactive power absorbed by any electrical equipment. The measurements are based on the Clark (a-b) and Park (d-q) transformations. The system is useful to teach electrical machines in Park’s coordinates and it allows also the study and control of some power electronics converters that are connected to three phase power network, such as static VAR compensator. The principle of the measuring method of the active ...
Basic, Duro; Malrait, François; Rouchon, Pierre
2008-01-01
A new Lagrangian formulation with complex currents is developed and yields a direct and simple method for modeling three-phase permanent-magnet and induction machines. The Lagrangian is the sum a mechanical one and of a magnetic one. This magnetic Lagrangian is expressed in terms of rotor angle, complex stator and rotor currents. A complexification procedure widely used in quantum electrodynamic is applied here in order to derive the Euler-Lagrange equations with complex sta...
Directory of Open Access Journals (Sweden)
Tine L. Vandoorn
2013-12-01
Full Text Available For islanded microgrids, droop-based control concepts have been developed both in single and three-phase variants. The three-phase controllers often assume a balanced network; hence, unbalance sharing and/or mitigation remains a challenging issue. Therefore, in this paper, unbalance is considered in a three-phase islanded microgrid in which the distributed generation (DG units are operated by the voltage-based droop (VBD control. For this purpose, the VBD control, which has been developed for single-phase systems, is extended for a three-phase application and an additional control loop is added for unbalance mitigation and sharing. The method is based on an unbalance mitigation scheme by DG units in grid-connected systems, which is altered for usage in grid-forming DG units with droop control. The reaction of the DG units to unbalance is determined by the main parameter of the additional control loop, viz., the distortion damping resistance, Rd. The effect of Rd on the unbalance mitigation is studied in this paper, i.e., dependent on Rd, the DG units can be resistive for unbalance (RU or they can contribute in the weakest phase (CW. The paper shows that the RU method decreases the line losses in the system and achieves better power equalization between the DG unit’s phases. However, it leads to a larger voltage unbalance near the loads. The CW method leads to a more uneven power between the DG unit’s phases and larger line losses, but a better voltage quality near the load. However, it can negatively affect the stability of the system. In microgrids with multiple DG units, the distortion damping resistance is set such that the unbalanced load can be shared between multiple DG units in an actively controlled manner rather than being determined by the microgrid configuration solely. The unit with the lowest distortion damping resistance provides relatively more of the unbalanced currents.
Designing a Three Phase Inverter for a Permanent Magnet Synchronous Motor
Dautermann, Lars
2013-01-01
The motivation for this thesis is to provide a three phase inverter for an electric car in the Formula Student. Designing an inverter is a challenge that requires combined knowledge in microcontroller programming, pcb layout, electric analysis and the principals of how to control a motor. The theory of electrical motors and especially permanent magnet synchronous motors is shortly introduced. The physical and electrical characteristics were studied to understand how the motor can be con...
Ju, Guannan; Cheng, Mengjiao; Xiao, Meng; Xu, Jianmei; Pan, Kai; Wang, Xing; Zhang, Yajun; Shi, Feng
2013-06-01
A "smart", functionally cooperating device consisting of a platinum strip and steel bead inside a nickel foam cube with a temperature-responsive polymer coating shows a diving-surfacing cycle when the water temperature first falls below and then rises above the lower critical solution temperature (LCST) of the polymer, which marks the change from superhydrophobicity to superhydrophilicity. Furthermore, the smart device allows a cycled directional delivery of lipophilic molecules between three phases. PMID:23636884
Slip Compensation in Efficiency-Optimized Three-Phase Induction Motor Drive Systems
Jamal M. Assbeihat; Mohammad Alia; Rateb Issa; Hussein Sarhan
2011-01-01
Energy efficiency optimization techniques of electrical drive systems improve the overall efficiency and reduce the hardness of mechanical characteristics of the drive system. It is therefore important to reduce the slip of induction motor to maintain its stable operation at different frequencies and loads. In this paper a slip compensator, based on fuzzy logic incremental controller has been developed to improve the steady state performance of efficiency-optimized three-phase induction motor...
High Performance Speed Sensorless Control of Three-Phase Induction Motor Based on Cloud Computing
Z. M. Salem; Abbas, M. A.
2012-01-01
Induction motor is a cast of alternating current motor where charge endures allotted to the rotor close-at-hand deputation of conductive charge. These motors are broadly applied in industrial claim due to they are arduous along with adhere no contacts. The speed controller of deltoid phase induction motor is applied to alleviate the aberration of speed. The central constructivist of this paper is to accrue the performance of speed sensorless control of three phase induction motor. To increase...
Analysis of three-phase power transformer laminated magnetic core designs
Directory of Open Access Journals (Sweden)
M.I. Levin
2014-03-01
Full Text Available Analysis and research into properties and parameters of different-type laminated magnetic cores of three-phase power transformers are conducted. Most of new laminated magnetic core designs are found to have significant shortcomings resulted from design and technological features of their manufacturing. These shortcomings cause increase in ohmic loss in the magnetic core, which eliminates advantages of the new core configurations and makes them uncompetitive as compared with the classical laminated magnetic core design.
Wang Changzhou; Song Jinchun
2012-01-01
The traditional large electroslag remelting furnaces have many shortages, such as high short-network impedance and inductance, long maintenance time for electrode replacement, low stiffness of driveline, and low control accuracy of remelting speed. The present research was aimed to solve these problems through structure modification and constant remelting speed control for a 120-t electroslag remelting (ESR) furnace. Based on the technique of three-phase double electrodes in series, the short...
Dynamic quenchers in fluorescently labeled membranes. Theory for quenching in a three-phase system.
Omann, G M; Glaser, M
1985-01-01
The theory for quenching of fluorescently labeled membranes by dynamic quenchers is described for a three-phase system: a fluorescently labeled membrane, a nonlabeled membrane, and an aqueous phase. Two different experimental protocols are possible to determine quenching parameters. Using the first protocol, partition coefficients and bimolecular quenching constants were determined for a hydrophobic quencher in carbazole-labeled membranes in the presence of an unlabeled reference membrane. Th...
Implementation of Closed Loop Bi-Directional Speed Control of PMBLDC Motor by FPGA
Directory of Open Access Journals (Sweden)
Aluru Ashokkumar
2013-08-01
Full Text Available This paper deals with Field Programmable Gate Array (FPGA based Permanent Magnet Brush Less DC (PMBLDC motor drive using IGBT smart power module based three phase voltage source inverter developed in this work. PMBLDC motor is widely used because of its high power density and simplicity. This motor necessarily needs a three-phase voltage source inverter and rotor position sensor (Hall sensor to detect the present position of the rotor and a circuit to appropriately trigger the suitable inverter switches to energize the corresponding phase windings so as to cause continuous rotation of the motor. FPGA implementation has the capability of executing several processes in parallel. Hence, the total control of the inverter together with the motor can be implemented in a single FPGA chip [1]. The use of Pulse Width modulation (PWM in power electronics to control high energy with maximum efficiency & power saving is not new but, interesting is to generate PWM signals using Hardware Descriptive Language (HDL and implementing it in FPGA [3], [7]. FPGA implementation of PWM is selected because it has provided an economic solution & fast circuit response due to its simultaneous instead of sequential execution. In this paper the FPGA based controller for BLDC motor is an experimental model implementation of Sinusoidal PWM strategy (SPWM control scheme. The proposed control scheme can be realized and the Simulation results are verified using FPGA SPARTAN-3A DSP Trainer kit from Xilinx with the help of VHDL programming algorithm of digital PWM Generator topology.
HARMONIC ANALYSIS OF SVPWM INVERTER USING MULTIPLE-PULSES METHOD
Directory of Open Access Journals (Sweden)
Mehmet YUMURTACI
2009-01-01
Full Text Available Space Vector Modulation (SVM technique is a popular and an important PWM technique for three phases voltage source inverter in the control of Induction Motor. In this study harmonic analysis of Space Vector PWM (SVPWM is investigated using multiple-pulses method. Multiple-Pulses method calculates the Fourier coefficients of individual positive and negative pulses of the output PWM waveform and adds them together using the principle of superposition to calculate the Fourier coefficients of the all PWM output signal. Harmonic magnitudes can be calculated directly by this method without linearization, using look-up tables or Bessel functions. In this study, the results obtained in the application of SVPWM for values of variable parameters are compared with the results obtained with the multiple-pulses method.
Modelling and Simulation of SVPWM Inverter Fed Permanent Magnet Brushless DC Motor Drive
Directory of Open Access Journals (Sweden)
DEVISREE SASI
2013-05-01
Full Text Available Variable speed drives with Pulse Width Modulation are increasingly applied in many new industrial applications for more efficient performance. Recently, developments in power electronics and semiconductor technology have lead to widespread use of power electronic converters in the power electronic systems. A number of Pulse width modulation (PWM schemes are used to obtain variable voltage and frequency supply from a three-phase voltage source inverter. Among the different PWM techniques proposed for voltage fed inverters, the sinusoidal PWM technique has been popularly accepted. But there is an increasing trend of using space vector PWM (SVPWM because of their easier digital realization, reduced harmonics, reduced switching losses and better dc bus utilization. This paper focuses on step by step development of SVPWM implemented on a PMBLDC motor. Simulation results are obtained using MATLAB/Simulink environment for effectiveness of the study.
An Improved Fault-Tolerant Control Scheme for PWM Inverter-Fed Induction Motor-Based EVs
Tabbache, Bekheira; Benbouzid, Mohamed; Kheloui, Abdelaziz; Bourgeot, Jean-Matthieu; Mamoune, Abdeslam
2013-01-01
This paper proposes an improved fault-tolerant control scheme for PWM inverter-fed induction motor-based electric vehicles. The proposed strategy deals with power switch (IGBTs) failures mitigation within a reconfigurable induction motor control. To increase the vehicle powertrain reliability regarding IGBT open-circuit failures, 4-wire and 4-leg PWM inverter topologies are investigated and their performances discussed in a vehicle context. The proposed fault-tolerant topologies require only ...
Measurement of Reactive Power in Three-Phase Electric Power Systems by Use of Walsh Functions
Directory of Open Access Journals (Sweden)
Adalet Abiyev
2010-12-01
Full Text Available Normal 0 false false false MicrosoftInternetExplorer4 Normal 0 false false false MicrosoftInternetExplorer4 Normal 0 false false false MicrosoftInternetExplorer4 This paper presents a new method for measuring of three-phase reactive power (RP in three-phase systems. Extraction of three-phase reactive power RP from entire instantaneous power signal is achieved by multiplication the phase instantaneous powers with the Walsh function(WF. This method simplifies the multiplication procedure required for the evaluation the tree-phase reactive power components due to the use of the peculiar properties of the WF. In contrast to the existing methods involving phase shift operation between the input voltage and current signals proposed measurement approach does not require the phase shift of the phase current signals to the 90 degrees with respect to the voltage signals. Limitations and proposals for future performance enhancements of the suggested method are also discussed. Validity and effectiveness of the suggested method have been tested by use of a simulation tools developed on the base of “Matlab 6.5”. The results obtained demonstrate that the computational demands can be substantially reduced by using the proposed method.
Modeling the columnar-to-equiaxed transition with a three-phase Eulerian approach
International Nuclear Information System (INIS)
A three-phase Eulerian approach is developed to model the columnar-to-equiaxed transition (CET) during solidification. The three phases are the parent melt, the solidifying columnar dendrites and the solidifying equiaxed grains. They are considered as spatially interpenetrating and interacting continua. We solve the conservation equations of mass, momentum, species and enthalpy for all three phases. Additionally we define and solve an additional transport equation for the number density of equiaxed grains which also accounts for grain nucleation. Diffusion controlled growth for both columnar and equiaxed phases, drag forces, species partitioning at the solid/liquid interface, heat of fusion, etc. are taken into account with the corresponding closure laws. A binary 'steel' (Fe-0.34 wt.% C) ingot casting as benchmark was simulated to demonstrate the model potentials. Preliminary results of the mixed columnar and equiaxed solidification including the motion of the columnar tip front, the occurrence of the CET, the formation of macrosegregations, and the resulting melt convection and grain sedimentation and their influence on the final macroscopic phase distribution are presented
1. K.Gurumoorthy,; 2.Dr.D.Prince Winston,; Lieutenant.J.Ganesan
2013-01-01
In the last decades, it has been observed that the harmonics distortions generated by the PV inverter are reduced by using Pulse with modulation technique. Harmonics reduction is the main consideration in three phase inductive load circuit.The performance of the three phase squirrel cage Induction motor was improved by the reduction of voltage harmonics and current harmonics. In this paper, the harmonic distortion of the three phase induction motor was measured in terms of THD by Simulation m...
Performance Analysis of Fuzzy Flatness Based Speed Control of Three Phase Induction Motor
Directory of Open Access Journals (Sweden)
C.SASIKUMAR, DR. C.MUNIRAJ
2013-05-01
Full Text Available Induction motor plays a vital role in engineering and industry. Induction motor offer a convenient means for controlling the operation of different equipment used in industry. Induction motor input supply will give from the voltage source inverter for its speed control purpose. If we connect induction motor directly to the AC supply its speed control will not applicable, so that we go inverter fed induction motor speed control. Gate pulse has been given by using FPGA processor. Fuzzy flatness program has been flashed in the FPGA processor for generating the gate pulse for VSI inverter. FPGA processor is directly fed to opto-coupler and the driver circuit and then it has given to VSI inverter. Her closed loop control has been achieved by using inductive type proximity sensor. In closed loop control when input voltage has been changed but speed of the induction motor has maintained constant. Fuzzy flatness based control is applied in the speed controller of induction motor. This method gives better efficiency of induction motor speed control. Fuzzy flatness controller method for induction motor gives better performance and reduces tracking error and reduces the torque ripple.
The PWM strategies of grid-connected distributed generation active NPC inverters
DEFF Research Database (Denmark)
Ma, Lin; Xinmin, Jin
2009-01-01
The Neutral Point Clamped topology due to high efficiency, low leakage current and EMI, its integration is widely used in the distributed generation (DG) systems. However the main disadvantage of the NPC inverter is given by an unequal distribution of the losses in the semiconductor devices, which leads to an unequal distribution of temperature. By using the Active NPC topology, the power losses distribution problem is alleviated. The modulation strategy is a key issue for losses distribution in this topology. In this paper two known strategies are discussed and a new proposed PWM strategy, namely the Adjustable Losses Distribution (ALD) PWM strategy is proposed for better losses distribution in the Active NPC (ANPC) topology. Simulations using Simulink and the PLECS toolbox have been done for evaluating efficiency of different NPC topologies and some experimental results are presented in this paper to validate the operation of the different strategies.
Performance of the Push-Pull LLC Resonant and PWM ZVS Full Bridge Topologies
Directory of Open Access Journals (Sweden)
S. Rama Reddy
2011-01-01
Full Text Available The soft switched PWM ZVS full bridge DC to DC converter and push-pull type LLC series resonant converter are compared for use in low output voltage power supply applications. It is shown that push-pull type LLC series resonant converter takes on the desirable characteristics of the conventional push-pull converter and LLC series resonant converter. Push-pull type has less conduction loss than that of full bridge converter. Analyses and simulation shows that for low power applications required turn ratio of the transformer is less so efficiency is more and switching stress is less for push-pull LLC series resonant converter than PWM ZVS full bridge DC to DC converter. The 48V DC is efficiently reduced to 12V DC using both DC to DC converters using 20KHZ switching frequency and all parameters are compared.
Modeling & Simulation of PWM Controlled Cycloconverter FED Split Phase Induction Motor
VINAMRA KUMAR GOVIL; YOGESH CHAURASIA
2013-01-01
Single Phase induction motors are widely accepted motor due to their energy efficient characteristics. To drive varying mechanical loads for long duty the machine needs to be controlled to increase its efficiency and minimize transient. To control the output parameters of the motor i.e., Speed and Electromagnetic torque the fixed frequency of the system is varied for which a Cycloconverter is employed along with PWM technique to increase the system efficiency. The Cycloconverter is built on w...
Closed loop control of ZVS half bridge DC-DC converter with DCS PWM Control
Directory of Open Access Journals (Sweden)
JANAPATI SIVAVARA PRASAD
2012-10-01
Full Text Available
The main drawback of the conventional symmetric control is that both primary switches in the converter operate at hard switching condition. Moreover, during the off-time period of two switches, the oscillation between the transformer leakage inductance and junction capacitance of the switches results in energy dissipation and electromagnetic interference (EMI emissions due to reverse recovery of MOSFETs body diodes. The asymmetric (complementary control was proposed to achieve ZVS operation for HB switches. However, asymmetric stresses distribution on the corresponding components may occur due to the asymmetric duty cycle distribution for the two primary switches. A new control scheme, to be known as duty-cycle shifted PWM (DCS PWM control, is proposed and applied to the conventional HB dc–dc converters to achieve ZVS for both the switches without adding extra components and without adding asymmetric penalties of the complementary control. The concept of this new control scheme is shifting one of the two symmetric PWM driving signals close to the other, such that ZVS may be achieved for the lagging switch due to the shortened resonant interval. Moreover, based on the DCS PWM control, a new half-bridge topology is proposed to achieve ZVS for both the main switches and auxiliary switch by adding an auxiliary switch and diode in the proposed half bridge. ZVS for the switch is achieved by utilizing the energy trapped in the leakage inductance. There are two control schemes. One is open loop and the other is closed loop. In open loop scheme, the given dc-dc converter is operating under disturbance. This disturbance effect is eliminated in closed loop scheme.
Softwareové fázové záv?sy PWM usm?r?ova?e.
Czech Academy of Sciences Publication Activity Database
Šimek, Petr; Škramlík, Ji?í; Valouch, Viktor
Brno : VUT FEKT Brno, 2009, s. 1-5. ISBN 978-80-214-3974-0. [Konference Elektrické pohony a výkonová elektronika - EPVE 09. Brno (CZ), 03.11.2009-04.11.2009] R&D Projects: GA MPO FT-TA5/123 Institutional research plan: CEZ:AV0Z20570509 Keywords : software phase lock loop * PWM rectifier * simulation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Space Vector PWM Control Synthesis for a H-Bridge Drive in Electric Vehicles
Abdelfatah, Kolli; Béthoux, Olivier; De Bernardinis, Alexandre; Labouré, Eric; Coquery, Gérard
2013-01-01
This paper deals with a synthesis of Space Vector PWM control methods applied for a H-bridge inverter feeding a 3-phase Permanent Magnet Synchronous Machine in Electric Vehicle application. First, a short survey of existing power converter architectures, especially those adapted to degraded operating modes, is presented. Standard SVPWM control methods are compared with three innovative ones using EV-drive specifications in the normal operating mode. Then, a rigorous analysis of the margins le...
High Frequency Soft Switching Of PWM Boost Converter Using Auxiliary Resonant Circuit
C. P. Sai Kiran; M. Vishnu Vardhan
2014-01-01
This thesis presents High frequency Soft Switching DC-DC boost Converter. The circuit consists of a general Boost Converter with an additional resonant circuit which has a switch, inductor, capacitor and a diode.In general Boost Converter circuits have snubber circuits where switching losses are dissipated in external passive resistors; which is known as hard switching. As the switching frequency of PWM converters is increased its switching losses and conduction losses also in...
SIMULATION AND ANALYSIS OF PWM-CONTROLLED QUASI-RESONANT CONVERTER FOR DRIVES
Helen Priscilla A.S.; Ms. Ashly Mary Tom
2012-01-01
This paper presents the development of a new resonant capacitor assisted pulse width modulationcontrolled quasi resonant converter with an auxiliary circuit which does the load regulation by controlling the ripple of the resonant voltage. This resonant converter is simulated through MATLAB/SIMULINK. This newly developed quasi resonant DC-DC converter can regulate its DC output under a principle of constant frequency soft switching commutation by a controllable PWM duty cycle control scheme. T...
Independent Control of Two Induction Motors Fed by a Five Legs PWM Inverter for Electric Vehicles
Tabbache, Bekheira; Rebaa, Kamel; Marouani, Khoudir; Benbouzid, Mohamed; Kheloui, Abdelaziz
2013-01-01
This paper deals with the implementation of an independent control of two induction motors fed by five legs PWM inverter. In this context, two Pulse Width Modulation techniques are presented in order to be included in the indirect field oriented control algoritm. Experiments and simulation are carried-out, on an induction motor drive, to show that the developed independ control of five legs inverter is effective and provides a simple configuration with high performance in terms of speed and t...
Rudolf Ribeiro Riehl; Ernesto Ruppert
2012-01-01
A proposta deste trabalho é apresentar uma nova metodologia para determinaçăo experimental das capacitancias parasitas do motor de induçăo trifásico de rotor em gaiola. As capacitancias parasitas fazem parte do circuito equivalente do motor para estudos de interferęncia eletromagnética causada no motor de induçăo em modo comum quando ele for acionado por inversor controlado por modulaçăo por largura de pulsos (MLP). Os procedimentos propostos para o desenvolvimento deste novo método consistem...
Modeling & Simulation of PWM Controlled Cycloconverter FED Split Phase Induction Motor
Directory of Open Access Journals (Sweden)
VINAMRA KUMAR GOVIL
2013-03-01
Full Text Available Single Phase induction motors are widely accepted motor due to their energy efficient characteristics. To drive varying mechanical loads for long duty the machine needs to be controlled to increase its efficiency and minimize transient. To control the output parameters of the motor i.e., Speed and Electromagnetic torque the fixed frequency of the system is varied for which a Cycloconverter is employed along with PWM technique to increase the system efficiency. The Cycloconverter is built on with IGBT due to its improved dynamic performance and efficiency and reduction in the level of audible noise. Low driving power and a simple drive circuit due to the input MOS gate structure. It can be easily controlled as compared to current controlled devices (Thyristor, BJT in high voltage and high current applications. With the help of PWM the output voltage control can be obtained without addition of any external components and PWM minimizes the lower order harmonics, while the higher order harmonics can be eliminated using a filter
Directory of Open Access Journals (Sweden)
B.S.V.S.R. Krishna
2012-06-01
Full Text Available Fluidization is an operation in which solid particles are kept under suspension supported by the upward flow of liquid/gas phase. In classic fluidization the solids density are higher than the liquid, where as in Inverse fluidization the solids density are lower than that of continuous liquid phase. The phase holdup measurements in three phase classic/inverse fluidized beds are very important and difficult to measure. The phase holdups can be estimated with the help of pressure drop data and height of the bed/solids mass balance with an assumption of axial uniform solid holdup. In most of the fluidized bed operations, such as Catalytic fluidized bed and slurry bubble columns the solids holdup varies axially. Such type of systems, holdups estimation is very difficult. The present study is focused on electrical conductivity method to get directly the cross sectional liquid holdup and pressure drop to solve the above problem of axial solid holdup variation and can readily be obtained the cross sectional three phase holdups. The averaged normalized conductance and the liquid holdup are related with liquid conductivity with a power law mode of equation. The dependency of conductivity on liquid also varies with electrode size and non-conducting medium (gas/solid. The experimental results showed that the conductivity method developed in this work was convenient for use and had a good accuracy in a wide range of liquid holdup (0.4 to 1 in the Gas-Liquid?Solid three-phase fluidized bed systems. The effect of temperature on conductivity of liquid phase was also verified and successfully correlated.
International Nuclear Information System (INIS)
A transformer-type superconducting fault current limiter (SFCL) can control fault current by adjusting a turn's ratio of the primary and secondary windings. In addition, by inserting a neutral line into the secondary winding, the power burden of the superconducting elements can be evenly distributed. We compared the operating and transient characteristics of the three-phase resistive and transformer-type SFCLs in the balanced and unbalanced faults that occur in power systems. In transformer-type SFCLs, where the primary and secondary windings of each phase were connected to one iron core, flux was induced to each winding of the normal phases by the fault current of the fault phase, thus causing simultaneous quench between superconducting elements. In the three-phase power systems, however, when faults occurred in more than two phases, the flux from fault current of the fault phase affected the other normal phase, thus decreasing the reduction ratio of fault current. We confirmed, however, that the fault current was reduced by 70% relative to cases without SFCLs. The results of the analysis of the transient characteristics of the three-phase transformer-type SFCL through the symmetrical component calculus showed that in the case of triple line-to-ground fault, a difference between positive and negative phase currents was large enough to cause an increase in the phase angle (?) between the generator creating the power and the motor acting as a load. Thus, we expect thator acting as a load. Thus, we expect that the transient stability deteriorates.
DESIGN AND DEVELOPMENT OF GAS-LIQUID CYLINDRICAL CYCLONE COMPACT SEPARATORS FOR THREE-PHASE FLOW
Energy Technology Data Exchange (ETDEWEB)
Dr. Ram S. Mohan; Dr. Ovadia Shoham
2001-10-30
This report presents a brief overview of the activities and tasks accomplished during the second half year (April 1, 2001-September 30, 2001) of the fourth project year budget period (October 1, 2000-September 30, 2001). An executive summary is presented initially followed by the tasks of the current budget period. Then, detailed description of the experimental and modeling investigations are presented. Subsequently, the technical and scientific results of the activities of this project period are presented with some discussions. The findings of this investigation are summarized in the ''Conclusions'' section followed by relevant references. The fourth project year activities are divided into three main parts, which are carried out in parallel. The first part is continuation of the experimental program that includes a study of the oil/water two-phase behavior at high pressures and control system development for the three-phase GLCC{copyright}. This investigation will be eventually extended for three-phase flow. The second part consists of the development of a simplified mechanistic model incorporating the experimental results and behavior of dispersion of oil in water and water in oil. This will provide an insight into the hydrodynamic flow behavior and serve as the design tool for the industry. Although useful for sizing GLCC{copyright} for proven applications, the mechanistic model will not provide detailed hydrodynamic flow behavior information needed to screen new geometric variations or to study the effect of fluid property variations. Therefore, in the third part, the more rigorous approach of computational fluid dynamics (CFD) will be utilized. Multidimensional multiphase flow simulation at high pressures and for real crude conditions will provide much greater depth into the understanding of the physical phenomena and the mathematical analysis of three-phase GLCC{copyright} design and performance.
Three-phase metal kinetics in terrestrial invertebrates exposed to high metal concentrations
Energy Technology Data Exchange (ETDEWEB)
Laskowski, Ryszard, E-mail: ryszard.laskowski@uj.edu.pl [Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Krakow (Poland); Bednarska, Agnieszka J. [Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Krakow (Poland); Spurgeon, David; Svendsen, Claus [Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxon, OX10 8BB (United Kingdom); Gestel, Cornelis A.M. van [Institute of Ecological Science, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands)
2010-08-15
Models of metal toxicokinetics are critically evaluated using both newly generated data in the NoMiracle project as well as those originating from older studies. The analysis showed that the most frequently used one-compartment two-phase toxicokinetic model, with one assimilation and one elimination rate constant, does not describe correctly certain data sets pertaining particularly to the pattern of assimilation of trace elements. Using nickel toxicokinetics in carabid beetles and earthworms as examples, we showed that Ni in fact exhibits a three-phase kinetics with a short phase of fast metal accumulation immediately after exposure, followed by partial elimination to an equilibrium concentration at a later stage of a metal exposure phase, and by final elimination upon transfer to an uncontaminated food/soil. A similar phenomenon was also found for data on cadmium kinetics in ground beetles and copper kinetics in earthworms in data already published in the literature that was not accounted for in the earlier analysis of the data. The three-phase model suggests that the physiology of controlling body metal concentrations can change shortly after exposure, at least in some cases, by increasing the elimination rate and/or decreasing metal assimilation. Hence, the three-phase model, that allows for different assimilation and/or elimination rates in different phases of exposure to a toxicant, may provide insight into temporal changes in the physiology of metal handling. Consequently, this alternative model should always be tested when describing metal toxicokinetics when temporal patterns of internal metal concentration exhibit an initial 'overshoot' in body metal concentrations.
Three-phase metal kinetics in terrestrial invertebrates exposed to high metal concentrations
International Nuclear Information System (INIS)
Models of metal toxicokinetics are critically evaluated using both newly generated data in the NoMiracle project as well as those originating from older studies. The analysis showed that the most frequently used one-compartment two-phase toxicokinetic model, with one assimilation and one elimination rate constant, does not describe correctly certain data sets pertaining particularly to the pattern of assimilation of trace elements. Using nickel toxicokinetics in carabid beetles and earthworms as examples, we showed that Ni in fact exhibits a three-phase kinetics with a short phase of fast metal accumulation immediately after exposure, followed by partial elimination to an equilibrium concentration at a later stage of a metal exposure phase, and by final elimination upon transfer to an uncontaminated food/soil. A similar phenomenon was also found for data on cadmium kinetics in ground beetles and copper kinetics in earthworms in data already published in the literature that was not accounted for in the earlier analysis of the data. The three-phase model suggests that the physiology of controlling body metal concentrations can change shortly after exposure, at least in some cases, by increasing the elimination rate and/or decreasing metal assimilation. Hence, the three-phase model, that allows for different assimilation and/or elimination rates in different phases of exposure to a toxicant, may provide insight into temporal changes in the physiology of metal handling. Cges in the physiology of metal handling. Consequently, this alternative model should always be tested when describing metal toxicokinetics when temporal patterns of internal metal concentration exhibit an initial 'overshoot' in body metal concentrations.
DESIGN AND DEVELOPMENT OF GAS-LIQUID CYLINDRICAL CYCLONE COMPACT SEPARATORS FOR THREE-PHASE FLOW
Energy Technology Data Exchange (ETDEWEB)
Dr. Ram S. Mohan; Dr. Ovadia Shoham
2001-04-30
This report presents a brief overview of the activities and tasks accomplished during the first half year (October 1, 2000-March 31, 2001) of the fourth project year budget period (October 1, 2000-September 30, 2001). An executive summary is presented initially followed by the tasks of the current budget period. Then, detailed description of the experimental and modeling investigations are presented. Subsequently, the technical and scientific results of the activities of this project period are presented with some discussions. The findings of this investigation are summarized in the ''Conclusions'' section followed by relevant references. The fourth project year activities are divided into three main parts, which are carried out in parallel. The first part is continuation of the experimental program that includes a study of the oil/water two-phase behavior at high pressures and control system development for the three-phase GLCC{copyright}. This investigation will be eventually extended for three-phase flow. The second part consists of the development of a simplified mechanistic model incorporating the experimental results and behavior of dispersion of oil in water and water in oil. This will provide an insight into the hydrodynamic flow behavior and serve as the design tool for the industry. Although useful for sizing GLCC{copyright} for proven applications, the mechanistic model will not provide detailed hydrodynamic flow behavior information needed to screen new geometric variations or to study the effect of fluid property variations. Therefore, in the third part, the more rigorous approach of computational fluid dynamics (CFD) will be utilized. Multidimensional multiphase flow simulation at high pressures and for real crude conditions will provide much greater depth into the understanding of the physical phenomena and the mathematical analysis of three-phase GLCC{copyright} design and performance.
Energy Technology Data Exchange (ETDEWEB)
Hong, Chae Moon; Ahn, Byeong Cheol; Choi, So Young; Kim, Do Hoon; Lee, Sang Woo; Kwon, Tae Geon; Lee, Jaetae [Kyungpook National Univ., Daegu (Korea, Republic of)
2012-09-15
Bisphosphonate (BP) related osteonecrosis of the jaw (BRONJ) is a well known serious complication of BP treatment. This study was undertaken to evaluate the diagnostic usefulness of three phase bone scintigraphy in patients with BRONJ. Forty one patients (48 lesions)with clinically proven BRONJ (2 males, 39 females, age 74.3{+-}6.7 years)under went Tc 99m HDP bone scintigraphy. Visual interpretation and semiquantitative analysis of uptakes using lesion to contralateral uptake ratios during the blood pool phase (BUR)and during the osseous phase (OUR)were performed, and relations were sought between these and various clinical parameters. Three phase bone scintigraphy showed increased perfusion and blood pooling in 21 (63.6%)and 27 (81.8%)of 33 lesions, respectively. The osseous phase was positive for 45 (93.8%)of the 48 lesions. Of the four inflammatory clinical parameters of BRONJ [pus discharge, pain, swelling, and erythrocyte sedimentation rate (ESR)], patients with three or more parameters had more positive findings in vascular and blood pool phase images (p=0.033, p=0.027). By semiquantitative analysis, patients with a positive ESR had statistically higher BUR and OUR (both p<0.001). Higher stage BRONJ lesions had higher OUR than lower stage lesions (p=0.003). In addition, bone scintigraphy revealed three clinically covert BRONJ lesions without bone exposure, and four patients were up staged based on bone scintigraphy. Bone scintigraphy provides a relatively sensitive means of detecting BRONJ, so it was helpful for accurate BRONJ staging. Furthermore, Increased uptakes in vascular and blood pool phases of three phase bone scintigraphy were related to the inflammatory activity of BRONJ.
One-dimensional modelling of phase holdups in three-phase stratified flow
Energy Technology Data Exchange (ETDEWEB)
Khor, S.H.; Mendes-Tatsis, M.A.; Hewitt, G.F. [Imperial Coll. of Science, Technology and Medicine, Chemical Engineering and Chemical Technology Dept., London (United Kingdom)
1997-09-01
This paper reports an investigation of the application of the three-fluid model to estimate phase holdups in three-phase stratified flow. A computer code (PRESBAL) was developed and used to apply the three-fluid model with a variety of assumptions regarding modelling of wall and interface shear stresses. Alternative definitions of equivalent diameters were also investigated. Experimental data for oil-water-air stratified flow obtained from the high pressure multiphase flow WASP facility and the data published by others have been chosen to compare with the various predictions. (author)
Directory of Open Access Journals (Sweden)
Mihaela Popescu
2014-09-01
Full Text Available This paper analyses the influence of the prescribed DC-link voltage on the filtering efficiency, in terms of current harmonic distortion after compensation, in a three-phase three-wire shunt active power line conditioner. The AC voltage controller as nonlinear load and two configurations of the coupling filter are taken into consideration. It is pointed out that, for each rms current to be compensated, there is an optimal set value of the DC-link voltage which minimizes the supply current distortion after compensation. Experimental tests validate the simulation results.
Implementation of Single Phase Hybrid Active Power Filter for Single & Three Phase Systems
V. OBUL REDDY, POOJARI VIDYA SAGAR
2013-01-01
Abstract:This paper presents an implementation of hybrid active power filter for decreasing the distortions in currents in a single-phase and three phase systems. In this method, the active power filter is injecting equal but opposite current to mitigate the distortion current shape the supply current to a sinusoidal form and in phase with the supply voltage. To reduce switching stress, losses a single-switch parallel active power filter is used. for removing the high order and low order harm...
Skull base osteomyelitis: role of three phase and hybrid SPECT/CT bone scintigraphy
International Nuclear Information System (INIS)
Full text: Skull base osteomyelitis is the infection that has spread to the skull base, beyond the external auditory canal and seen in advanced stage of malignant otitis externa. Early diagnosis of this condition includes the use of bone scintigraphy since clinical assessment alone cannot differentiate the skull base osteomyelitis from the severe type of otitis externa in which there is no extension to the adjacent bone. Objective: To determine the role of three phase bone scintigraphy and delayed SPECT/CT in detection of skull base osteomyelitis in patients with malignant otitis externa. Material and Methods: Clinical records of 20 patients (14 Males and 6 Females; mean age 72 yrs) of otitis externa with suspected skull base involvement referred for bone scintigraphies were analyzed retrospectively. Three phase bone scintigraphy was acquired under dual detector gamma camera after intravenous injection of 20 mCi (740 MBq) 99mTc-MDP followed by SPECT/CT of the skull. Scintigraphic findings were compared with clinical symptoms, signs and diagnostic CT scan findings. Results: All the patients except one were diabetic and having elevated ESR. 18 patients presented with bilateral symptoms and rest unilateral. Cranial nerves were involved in 8 patients (40%). Ear discharge culture sensitivity report was found in three patients; it was positive for Pseudomonas aeruginosa for two patients and in Diptheroids for one. In 9 patients (45%) increased flow of tracer and 10 patients (50%) increased blood pool phase in the temporal region was found. Delayed phase images showed increased uptake in skull bone in 19 patients (95%). Hybrid SPECT/CT of the skull localized areas of increased tracer uptake to the mastoid part in 15 patients (75%), petrous part in 11 patients (55%), sphenoid in 3 patients (15%) and zygomatic bone in one patient (5%) with CT showing destructive changes in 5 patients (25%) which were corroborated with diagnostic CT findings. SPECT/CT along with three phase bone scan findings were suggestive of active inflammation in 10 patients (50%) which changed the management in 5 patients (25%). Conclusion: Three phase bone scintigraphy and Hybrid SPECT/CT is a sensitive modality in detection of skull base osteomyelitis in cases of malignant otitis externa
Modeling and Control of Three-Phase Shunt Active Power Filter
Directory of Open Access Journals (Sweden)
Moleykutty George
2008-01-01
Full Text Available In this research the performance of a three-phase shunt active power filter (APF using Model Reference Controller (MRC has been compared with that using instantaneous active and reactive (p-q theory. The novelty of this research lies in the application of MRC to generate the amplitude of the reference supply current required by the APF circuit and the successful implementation of the APF system for harmonic elimination. The entire system has been modeled using MATLAB 6.1 toolbox. Simulation results demonstrate the applicability of MRC for the control of APF.
Vector control of three-phase AC machines system development in the practice
Phung Quang, Nguyen
2015-01-01
This book addresses the vector control of three-phase AC machines, in particular induction motors with squirrel-cage rotors (IM), permanent magnet synchronous motors (PMSM) and doubly-fed induction machines (DFIM), from a practical design and development perspective. The main focus is on the application of IM and PMSM in electrical drive systems, where field-orientated control has been successfully established in practice. It also discusses the use of grid-voltage oriented control of DFIMs in wind power plants. This second, enlarged edition includes new insights into flatness-based nonlinear
Fault Strategy Analysis for Three-phase Cascaded Multi-level Inverter
Directory of Open Access Journals (Sweden)
E. Parimalasundar
2015-02-01
Full Text Available This study includes a multilevel cascaded inverter along with a control strategy. This proposed control scheme directs the inverter to support the grid under three - phase balanced voltage sags and during one or two - phase faults. Control of voltage between grid and Distributed Generation (DG system is a challenging subject. Integrating DG with the grid is the fundamental element of this study which depends on grid codes prescribed by the transmission system operators. These electrical dispatching standards endow smartness and flexibility of DGs. The proposed system is designed using MATLAB/Simulink tool. Simulated results show the feasibility of the proposed control scheme.
A note on stability in three-phase-lag heat conduction
Energy Technology Data Exchange (ETDEWEB)
Quintanilla, Ramon [Department of Applied Mathematics II, UPC Terrassa, Colom 11, 08222 Terrassa (Spain); Racke, Reinhard [Department of Mathematics and Statistics, University of Konstanz, 78457 Konstanz (Germany)
2008-01-15
In this note we consider two cases in the theory of the heat conduction models with three-phase-lag. For each one we propose a suitable Lyapunov function. These functions are relevant tools which allow to study several qualitative properties. We obtain conditions on the material parameters to guarantee the exponential stability of solutions. The spectral analysis complements the results and we show that if the conditions obtained to prove the exponential stability are not satisfied, then we can obtain the instability of solutions for suitable domains. We believe that this kind of results is fundamental to clarify the applicability of the models. (author)
Experimental and Computational Studies of Hydrodynamics in Three-Phase and Two-Phase Fluidized Beds
Bahary, Mitra
The objective of the present study was to investigate the hydrodynamics of three-phase fluidized beds, their rheology, and experimentally verify a predictive three fluid hydrodynamic model developed at the Illinois Institute of Technology, Chicago. The recent thorough reviews by L. S. Fan, B. L. Tarmy and C. A. Coulaloglou (1990) show that there exist no such models in the literature. The IIT hydrodynamic model computes the phase velocities and the volume fractions of gas, liquid, and particulate phases. Model verification involves a comparison of these computed velocities and volume fractions to experimental values. In this thesis, a three fluid model is presented. The input into the model can be particulate viscosities either measured with a Brookfield viscometer or derived using the mathematical techniques of kinetic theory of granular flows pioneered by Savage and others. The computer simulation of a three-phase fluidized bed in an asymmetric mode qualitatively predicts the gas, liquid and solid hold-ups (volume fractions) and flow patterns in the industrially important churn-turbulent (bubbly coalesced) regimes. The computations in a fluidized bed with a symmetric distributor incorrectly showed no bubble coalescence. A combination of X-ray and gamma -ray densitometers was used to measure the solids and the liquid volume fractions in a two dimensional bed in the bubble coalesced regime. There is a good agreement between the theory for an asymmetric distributor and the experiments. The porosity fluctuation signals inside two phase and three phase fluidized beds were detected by using a gamma-ray absorption technique and analyzed by means of the fast Fourier transform (FFT) power spectrum method. The measurements indicated that the bubble coalescence and break-up could be detected by using such techniques. The experimental and simulation porosity fluctuations and bubble frequencies show a fair comparison. A high resolution micro-imaging/measuring system apparatus was used to measure instantaneous and time averaged particle velocities. The fluctuations of particle velocities around their average values were found to be approximately Maxwellian. The measured time averaged velocities compare well with the predicted velocities for an asymmetric distributor used in this study. A Brookfield viscometer was used to measure the "apparent" bed viscosity in two three-phase fluidized beds. The viscosities were also calculated from measurements of particle oscillations (granular temperatures) using a high resolution micro-imaging/measuring system. To obtain these viscosities a dense phase kinetic theory formula derived in D. Gidaspow's book (1994) was used. There is an excellent agreement between the macroscopically measured viscosities using a Brookfield viscometer and those computed from particle fluctuations and collisions using kinetic theory.
Secondary Voltage Unbalance Compensation for Three-Phase Four-Wire Islanded Microgrids
DEFF Research Database (Denmark)
Tang, Fen; Zhou, Xiao
2014-01-01
This paper proposes a secondary voltage unbalance control approach that compensate voltage unbalances in three-phase four-wire islanded microgrid systems. It is implemented in the secondary control level of the microgrid hierarchical control structure. By sending information through low-bandwidth communication links to the primary control level, the required unbalanced factors at sensitive buses are achieved. Also, negative and zero sequence equivalent circuits and unbalance compensation principle are derived. Finally, real-time hardware-in-the-loop results show the feasibility of the proposed approach for different islanded scenarios.
Optimal power flow based on glow worm-swarm optimization for three-phase islanded microgrids
DEFF Research Database (Denmark)
Quang, Ninh Nguyen; Sanseverino, Eleonora Riva
2014-01-01
This paper presents an application of the Glowworm Swarm Optimization method (GSO) to solve the optimal power flow problem in three-phase islanded microgrids equipped with power electronics dc-ac inverter interfaced distributed generation units. In this system, the power injected by the distributed generation units and the droop control parameters are considered as variables to be adjusted by a superior level control. Two case studies with different optimized parameters have been carried out on a 6-bus test system. The obtained results showed the effectiveness of the proposed approach and overcomes the problem of OPF in islanded microgrids showing loads unbalance.
Coriolis mass flow metering for three-phase flow: A case study
Henry, M.; Tombs, M; Zamora, M; Zhou, F.
2013-01-01
Previous work has described the use of Coriolis mass flow metering for two-phase (gas/liquid) flow. As the Coriolis meter provides both mass flow and density measurements, it is possible to resolve the mass flows of the gas and liquid in a two-phase mixture if their respective densities are known. To apply Coriolis metering to a three-phase (oil/water/gas) mixture, an additional measurement is required. In the work described in this paper, a water cut meter is used to indicate what proportion...
Modeling of a three-phase reactor for bitumen-derived gas oil hydrotreating
Chacón, R.; CANALE, A.; A. Bouza; Y. Sánchez
2012-01-01
A three-phase reactor model for describing the hydrotreating reactions of bitumen-derived gas oil was developed. The model incorporates the mass-transfer resistance at the gas-liquid and liquid-solid interfaces and a kinetic rate expression based on a Langmuir-Hinshelwood-type model. We derived three correlations for determining the solubility of hydrogen (H2), hydrogen sulfide (H2S) and ammonia (NH3) in hydrocarbon mixtures and the calculation of the catalyst effectiveness factor was include...
Next-generation three-phase inverters. Phase one annual report, 1996
Energy Technology Data Exchange (ETDEWEB)
Wesley, A; Wills, R [Advanced Energy Systems Inc., Wilton, NH (United States)
1997-07-01
The PV-MaT 4A subcontract addresses the cost effective manufacture of PV related end-products. Advanced Energy Systems Inc. (AES Inc.) has undertaken NREL contract No. ZAF-4-14271-10, {open_quotes}Next Generation Three Phase Inverter{close_quotes}, to combine leading industry skill with state-of-the-art technologies to realize cutting-edge PV inverter related products. To this end, in phase one of the PV-MaT contract, AES Inc. has made significant inroads toward establishing low cost manufacture of an intelligent controller PV-hybrid product.
Directory of Open Access Journals (Sweden)
Mohammad Sarvi, Iman Soltani
2013-07-01
Full Text Available In this paper has used positive, negative and combined switching strategies for three phase ac/ac matrix converter.the author compares these strategies. The performance comparison of these three strategies is made under balanced operation. The simulation of three phase matrix converter feeding a three phase load was accomplished by means of the matlab/simulink software. After the simulation the comparison of the waveforms THD in three switching sequence is done. It must be mentioned that the duty cycle of the whole switches in the converter is according to Venturini switching algorithm.
Three-phase bone studies in hemiplegia with reflex sympathetic dystrophy and the effect of disuse
International Nuclear Information System (INIS)
Eighty-five patients with cerebral vascular accidents were assessed with three-phase bone scintigraphy of the hands and with whole-body delayed bone imaging. Nine patients (10%) had normal three-phase bone images. Fifty-five patients (65%) showed decreased blood flow and blood-pool images of the hands and wrists with normal delayed bone scintigrams, indicating the effect of paralysis or disuse. Twenty-one patients (25%) had diffuse increased uptake with periarticular accentuation, felt to be bone-scintigraphic evidence of reflex sympathetic dystrophy of the hands and wrists; in two patients this occurred before its clinical appearance. Thriteen of the 21 reflex sympathetic dystrophy syndromes (RDS)-involved limbs (62%) had increased blood flow, whereas 8 (38%) had decreased flow. Gross limb blood flow appears to be related to the degree of muscle activity, but flow may be altered by the presence of sympathetic changes. A possible dissociation between whole-limb flow and bone blood flow in paralyzed limbs involved with RDS is discussed
Development of theory-based health messages: three-phase programme of formative research.
Epton, Tracy; Norman, Paul; Harris, Peter; Webb, Thomas; Snowsill, F Alexandra; Sheeran, Paschal
2015-09-01
Online health behaviour interventions have great potential but their effectiveness may be hindered by a lack of formative and theoretical work. This paper describes the process of formative research to develop theoretically and empirically based health messages that are culturally relevant and can be used in an online intervention to promote healthy lifestyle behaviours among new university students. Drawing on the Theory of Planned Behaviour, a three-phase programme of formative research was conducted with prospective and current undergraduate students to identify (i) modal salient beliefs (the most commonly held beliefs) about fruit and vegetable intake, physical activity, binge drinking and smoking, (ii) which beliefs predicted intentions/behaviour and (iii) reasons underlying each of the beliefs that could be targeted in health messages. Phase 1, conducted with 96 pre-university college students, elicited 56 beliefs about the behaviours. Phase 2, conducted with 3026 incoming university students, identified 32 of these beliefs that predicted intentions/behaviour. Phase 3, conducted with 627 current university students, elicited 102 reasons underlying the 32 beliefs to be used to construct health messages to bolster or challenge these beliefs. The three-phase programme of formative research provides researchers with an example of how to develop health messages with a strong theoretical- and empirical base for use in health behaviour change interventions. PMID:24504361
Measurement and PC-SAFT modelling of three-phase behaviour.
Rodríguez-Palmeiro, Iago; Rodríguez, Oscar; Soto, Ana; Held, Christoph
2015-01-21
Modelling of multi-component systems with complex interactions is an ongoing challenge in thermodynamics due to their great relevance in industry and academia. Systems that build three liquid phases are found in many interesting applications (separation processes, triphasic catalysis…). Among them, the surfactant flooding method for enhanced oil recovery is noticeable. In this method, a stable solution of water, surfactants, co-surfactants, salts and other components is injected into the reservoir. The optimal formulation of this surfactant system is associated with a three-phase behaviour in which the interfacial tension becomes significantly low. In this work, the PC-SAFT equation of state was used for the first time to predict the equilibrium involved in triphasic systems using solely pure-component parameters. The model without any fitting parameter was able to predict the three-phase behaviour. A great agreement between experimental and predicted compositions for (water + [C10mim][NTf2] + n-dodecane) and (water + [C12mim][NTf2] + n-dodecane) ternary systems at 298.15 K and atmospheric pressure was found. At 348.15 K slightly higher deviations were found, which can be compensated by the introduction of just one binary interaction parameter. The success of this achievement could mean an important advancement in upstream oil operations, enabling a faster and cheaper method to carry out an initial screening of potential surfactants. PMID:25464376
An Improved Control Strategy for the Three-Phase Grid-Connected Inverter
DEFF Research Database (Denmark)
Yao, Zhilei; Xiao, Lan
2015-01-01
An improved control strategy for the three-phase grid-connected inverter with space vector pulse width modulation (SVPWM) is proposed. When the grid current contains harmonics, the d- and q-axis grid currents will be interacted, and then the waveform quality of the grid current will be poorer. As the reference output voltage cannot directly reflect the change of the reference grid current, the dynamic response of the grid-connected inverter is slow. In order to solve the aforementioned problems, the d- and q-axis grid currents in the decoupled components of the grid current controller can be substituted by the d- and q-axis reference grid currents, respectively. The operating principles of the traditional and proposed control methods are illustrated. Experimental results for a 15-kVA three-phase grid-connected inverter with SVPWM verify the theoretical analysis. Compared with the traditional control strategy, the grid-connected inverter with the improved control strategy has high waveform quality of the grid current, small ripple power, and fast dynamic response.
Improved modeling of new three-phase high voltage transformer with magnetic shunts
Directory of Open Access Journals (Sweden)
Chraygane M.
2015-03-01
Full Text Available This original paper deals with a new approach for the study of behavior in nonlinear regime of a new three-phase high voltage power supply for magnetrons, used for the microwave generators in industrial applications. The design of this system is composed of a new three-phase leakage flux transformer supplying by phase a cell, composed of a capacitor and a diode, which multiplies the voltage and stabilizes the current. Each cell. in turn, supplies a single magnetron. An equivalent model of this transformer is developed taking into account the saturation phenomenon and the stabilization process of each magnetron. Each inductance of the model is characterized by a non linear relation between flux and current. This model was tested by EMTP software near the nominal state. The theoretical results were compared to experimental measurements with a good agreement. Relative to the current device, the new systemprovides gains of size, volume, cost of implementation and maintenance which make it more economical.
Design and Development of Gas-Liquid Cylindrical Cyclone Compact Separators for Three-Phase Flow
Energy Technology Data Exchange (ETDEWEB)
Mohan, R.S.; Shoham, O.
2001-01-18
The objective of this five-year project (October 1997 - September 2002) was to expand the current research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project was executed in two phases. Phase I (1997 - 2000) focused on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC) Separator. The activities of this phase included the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase II (2000 - 2002), the developed GLCC separator will be tested under high pressure and real crude conditions. This is crucial for validating the GLCC design for field application and facilitating easy and rapid technology deployment. Design criteria for industrial applications will be developed based on these results and will be incorporated into the mechanistic model by TUSTP.
Assessment of three-phase relative permeability models using laboratory hysteresis data
Energy Technology Data Exchange (ETDEWEB)
Element, D.; Masters, J.; Sargent, N. [ECL Technology Ltd., Dorset (United Kingdom); Jayasekera, T. [United Kingdom Dept. of Trade and Industry, London (United Kingdom)
2003-09-01
Hysteresis models are important in determining gas relative permeabilities in water-alternating-gas (WAG) injection wells. This study presents the analysis of a comprehensive laboratory study that provides calibration data for applying numerical simulation hysteresis models. WAG flooding causes lower gas mobilities which improves gas sweep and incremental recovery for WAG based in-situ oil recovery (IOR) processes. Calibration data is required to assess the numerical simulations of the process. Three-phase hysteresis models were developed to include the hysteresis effect, the trapping of gas, and the reduction of water relative permeability in the presence of trapped gas. Secondary and tertiary WAG floods were examined in both water-wet and intermediate wet Berea cores. Four separate sets of measured data were derived and in-situ saturation profiles were measured along with mass balance and pressure drop data. Hysteresis models can include: irreversibility of hysteresis cycles; potential for reduced residual oil saturation with trapping of gas by water; reduction in water and gas permeability; variation in fractional flow with trapped gas saturation; and, variation in land trapping factor between hysteresis cycles. Results confirm the need for three-phase hysteresis models. 15 refs., 6 tabs., 17 figs.
Flexible voltage support control for three-phase distributed generation inverters under grid fault
DEFF Research Database (Denmark)
Camacho, Antonio; Castilla, Miguel
2013-01-01
Ancillary services for distributed generation systems become a challenging issue to smartly integrate renewable energy sources into the grid. Voltage control is one of these ancillary services which can ride through and support the voltage under grid faults. Grid codes from the Transmission System Operators describe the behavior of the energy source, regulating voltage limits and reactive power injection to remain connected and support the grid under fault. On the basis that different kinds of voltage sags require different voltage support strategies, a flexible control scheme for three phase grid connected inverters is proposed. In three phase balanced voltage sags, the inverter should inject reactive power in order to raise the voltage in all phases. In one or two phase faults, the main concern of the distributed generation inverter is to equalize voltages by reducing the negative symmetric sequence and clear the phase jump. Due to system limitations, a balance between these two extreme policies is mandatory. Thus, over-voltage and undervoltage can be avoided, and the proposed control scheme prevents disconnection while achieving the desired voltage support service. The main contribution of this work is the introduction of a control algorithm for reference current generation that provides flexible voltage support under grid faults. Two different voltage sags have been experimentally tested to illustrate the behavior of the proposed voltage support control scheme.
A NOVEL CURRENT CONTROL TECHNIQUE FOR THREE PHASE SHUNT ACTIVE POWER FILTER
Directory of Open Access Journals (Sweden)
Rekha Soni*
2015-07-01
Full Text Available In this paper a novel control algorithm is implemented for three phase shunt active power filter based on adaptive hysteresis current controller. Harmonics is the predominant power quality issues which have adverse effect on the power system. The most of power quality issues in power system is created due to non linear loads. The shunt active power filter is extensively employed to eliminate harmonic current and reactive power compensation. The performance of shunt active power filter depends on the control strategy used for the shunt active filter. Hysteresis Current Controller is widely used due to its simplicity, fast and accurate response and ease in implementation but this leads to high switching losses and injects high frequency harmonic into the system due to its variable switching frequency. This paper provide the frame work for adaptive current controller SAPF which overcome the problem of hysteresis current control scheme. The proposed three phase SAPF is found to be effective which meets IEEE 519 standard recommended on harmonics levels. The simulation results, obtaining using Matlab/Simulink show the effectiveness of proposed control algorithm of the shunt active power filter.
A Novel Harmonic Elimination Approach in Three-Phase Multi-Motor Drives
DEFF Research Database (Denmark)
Davari, Pooya; Yang, Yongheng
2015-01-01
Power electronics technology has been widely used for decades in the modern motor drive systems. Beyond the control flexibility, the power electronics devices (e.g., diode rectifiers) are also the main harmonic source to the grid due to their nonlinearity, which deteriorate the power grid quality and may cause unnecessary losses in power system transformers. Both degradations are apt to occur in motor drive applications. As a consequence, it calls for advanced and intelligent control strategies for the power electronics based drive systems like adjustable speed drives in industry. At present, many industrial drives are still equipped with three-phase diode rectifiers. Thus, it is difficult to implement the prior-art harmonic control strategies for active front-ends. Moreover, the total cost and complexity has become an obstacle for these harmonic elimination approaches in multiple drive systems. Therefore, in this paper, a new cost-effective harmonic mitigation approach has been proposed for multipledrives. The proposed approach can control the generated current harmonics by benefiting of the nonlinearity of the drive units and through a novel current modulation scheme. Simulation and experimental results have validated the effectiveness of the proposed approach in terms of harmonic elimination in three-phase multi-drive systems.
Noise and Vibration Monitoring for Premium Efficiency IE 3 Three-Phase Induction Motors
Directory of Open Access Journals (Sweden)
NISTOR, C. G.
2015-08-01
Full Text Available The paper presents the original SV-100 platform that enables low-cost and very high accuracy determinations of noise and vibration levels. The aim of the proposed platform is to achieve an effective integration of the two topics of this analysis: vibrations and noises. To the best of our knowledge, no low price, dedicated compact platform with embedded measuring instruments exists. For proving the practical utility of the proposed platform, two induction motors of 7.5 kW and 11 kW, respectively, in single-layer winding, at 1000 rpm, with IE3 premium efficiency were analyzed. This analysis is required because, according to IEC60034-30 standard, the IE3 efficiency standard has become mandatory for induction motors of rated power greater than 7.5 kW. Therefore, in order to improve the motor operating efficiency, the power losses caused by noises and vibrations have to be reduced. Several variants of supply were studied, i.e., by the three-phase 50 Hz network and by a three-phase inverter at 40, 50 and 60 Hz, respectively. The experimental determinations of noises are presented comparatively, by using a Bruel&Kjaer sonometer and by using the new platform SV-100. The results are compared with the IEC60034 standard.
Strictly hyperbolic models of co-current three-phase flow withgravity
Energy Technology Data Exchange (ETDEWEB)
Juanes, Ruben; Patzek, Tadeusz W.
2002-11-18
We study the character of the equations in the traditional formulation of one-dimensional immiscible three-phase flow with gravity, in the limit of negligible capillarity. We restrict our analysis to co-current flow required for a displacement process; in cases of mixed co-current and counter-current flow, capillarity effects cannot be dropped from the formulation. The model makes use of the classical multiphase extension of Darcy's equation. It is well known that, if relative permeabilities are taken as fixed functions of saturations, the model yields regions in the saturation space where the system of equations is locally elliptic. We regard elliptic behavior as a nonphysical artifact of an incomplete formulation, and derive conditions on the relative permeabilities that ensure strict hyperbolicity of the governing equations. The key point is to acknowledge that a Darcy-type formulation is insufficient to capture all the physics of three-phase flow and that, consequently, the relative permeabilities are functionals that depend on the fluid viscosity ratio and the gravity number. The derived conditions are consistent with the type of displacements that take place in porous media. By means of an illustrative example, we show how elliptic behavior can be removed, even when using simplistic relative permeability models.
Direct Torque Control of Four Switch Three Phase Inverter fed Induction Motor Sensorless Speed Drive
Directory of Open Access Journals (Sweden)
Mohamed K Metwally
2014-10-01
Full Text Available This paper presents sensorless speed control of induction motor (IM using four switch three phase inverter (FSTPI with direct torque and flux control (DTFC. The proposed sensorless DTFC system consists of an adaptive observer of rotor flux to accurately estimate stator resistance and speed simultaneously, without affecting drive performances. The switching technique for DTFC of IM using FSTPI in low power application is based on the principle of similarity between FSTPI and SSTPI (six switch three phase inverter, where the ?? plan is divided into 6 sectors and the formation of the voltage space vector is done in the same way as for SSTPI by using effective (mean vectors. This approach allows using the well-known established switching table of SSTPI for FSTPI. The simulation results indicates that the sensorless speed control of FSTPI fed IM with DTFC and adaptive observer provides accurate estimate, good trajectory tracking with different dynamics performance. The experimental results verify the effectiveness of the proposed method at different operating points.
A dual-path, current-sensing resistor-free boost LED driver with fast PWM dimming
International Nuclear Information System (INIS)
A boost LED driver featuring a high PWM dimming ratio and optimized efficiency is presented. This LED driver, which has a low dropout voltage and is able to drive 3–7 LEDs in series with constant output current and fast PWM dimming, provides an alternative technique for brightness adjustment. A dual-path control scheme with automatic switching and state maintenance is proposed. Meanwhile, a cascode current mirror structure is applied with the output transistor multiplexed as an LED PWM dimming transistor. Implemented in 0.5 ?m 25 V BCD process, the measurement results show that a voltage conversion range of 5 V input to 6–24 V output with constant output current is obtained. With automatically switching dual-path control and an optimized current mirror, the response time during PWM dimming is reduced to as low as 240 ns and the efficiency keeps above 89% over a wide PWM dimming ratio - 250 mA output current. (semiconductor integrated circuits)
Adaptive Phase Synchronization Techniques for Unbalanced and Distorted Three-Phase Voltage System
Woinowsky-Krieger, Alexis
Interfacing and operating AC power electronic systems requires rapid and accurate estimation of the phase angle of the power source, and specifically of the positive sequence of the three-phase utility grid voltage. This is needed to ensure reliable operation of the power control devices and of the resulting power flow. However, the quality of this information is undermined by various distortions and unbalanced conditions of the three-phase grid voltage. Phase estimation and power control can both be performed in real time by a DSP, but a DSP typically has limited computational resources, especially in regards to speed and memory, which motivates the search for computationally efficient algorithms to accomplish these tasks. In contrast to conventional PLL techniques, recent approaches have used adaptive amplitude estimation to enhance the acquisition of the phase information, resulting in faster response and improved performance. This thesis presents a novel technique to estimate the phase of the positive sequence of a three-phase voltage in the presence of frequency variations and unbalanced conditions, referred to as hybrid negative sequence adaptive synchronous amplitude estimation with PLL, or H-NSASAE-PLL. The key feature consists of a feedback structure which embeds a positive sequence PLL and an adaptive synchronous negative sequence estimator to enhance the performance of the PLL. The resulting benefits include faster estimation of the phase of the positive sequence under unbalanced conditions with zero steady state error, simplified tuning of PLL parameters to address a wide range of application requirements, robust performance with respect to distortions and PLL parameters, a structure of minimal dynamical order (fifth) to estimate the main signal parameters of interest, simplified discretization, and reduced computational costs, making the proposed technique suitable for real time execution on a DSP. The H-NSASAE-PLL is developed in the Matlab/Simulink environment, and a specialized test signal generator is developed to evaluate it's performance. The overall system is executed, and experimental results are produced, in real time, on a dSPACE DS1104 controller board.
Scientific Electronic Library Online (English)
Igor V., Andrianov; Jan, Awrejcewicz; Galina A., Starushenko.
2013-01-01
Full Text Available A modified three-phase composite model yielding reliable effective characteristics of composite structures has been proposed. In particular, the problem of effective heat transfer coefficient of the composite structure with periodically located inclusions of circular cross-sections located on a squa [...] re net is solved. Advantages of the proposed model in comparison to the classical three-phase model are illustrated and discussed.
LAZAR, G. A.; ALEXA, D.; A Lazar; BUZATU, N. R.; MOISA, M.
2010-01-01
The paper presents the design and analysis of a three-phase static converter, composed of a Rectifier with Near Sinusoidal Input Currents (RNSIC), which ensures the DC bus voltage level for a three phase Incomplete Bridge Inverter (IBI), used to drive an asynchronous motor. The proposed circuit has a low input current harmonic content, can ensure the load overcurrent protection and has a better reliability. The converter can be designed to provide any required output maximum power under a ...
Efficient Voltage Regulation in Three Phase A.C. Transmission Lines Using Static VAR Compensator
Directory of Open Access Journals (Sweden)
AVNEESH KUMAR VISHWAKARMA
2013-05-01
Full Text Available Due to the rapid technological progress, the consumption of electric energy increases continuously. But the transmission systems are not extended to the same extent because building of new lines is difficult for environmental as well as political reasons. Hence, the systems are driven closer to their limits resulting in congestions and critical situations endangering the system security. Power Flow Control devices such as Flexible AC Transmission Systems (FACTS provide the opportunity to in?uence power ?ows and voltages and therefore to enhance system security, e.g. by resolving congestions and improving the voltage pro?le. From the last few years static var compensator plays an important role in voltage regulation in AC Transmission Systems. This paper deals with the designing and implementation of Static Var compensator for Efficient Voltage regulation in three phase A.C. transmission lines in MATLAB Simulink platform.
Three-phase permeabilities and other characteristics of 260-mD fired Berea
Energy Technology Data Exchange (ETDEWEB)
Maloney, D.; Brinkmeyer, A.
1992-04-01
A laboratory investigation was conducted to determine relative permeabilities and other characteristics of a 260-mD fired Berea sandstone. The mineralogical and physical characteristics of the sample were characterized by XRD tests, thin section analyses, mercury injection tests, and centrifuge capillary pressure and wettability tests. Two-phase oil/water relative permeabilities were measured under several stress conditions. Resistivity characteristics of the sample were also evaluated during several of the oil/water tests. Oil/gas and gas/water relative permeabilities were measured during steady-state tests. Three-phase steady-state oil/gas/water tests were performed for six DDI saturation trajectories (decreasing brine and oil saturations, increasing gas saturation) in which the sample was not cleaned between saturation trajectories.
Neuro-Fuzzy based Controller for a Three- Phase Four-Wire Shunt Active Power Filter
Directory of Open Access Journals (Sweden)
Mridul Jha
2011-10-01
Full Text Available This paper describes the application of a novel neuro-fuzzy based control strategy which is used in order to improve the Active Power Filter (APF dynamics to minimize the harmonics for wide range of variations of load current under various conditions. To improve dynamic behavior of a three phase four-wire shunt active power filter and its robustness under range of load variations, adaptive hysteresis band with instantaneous p-q theory is used with the inclusion of neural network filter for reference current generation and fuzzy logic controller for DC voltage control. The proposed control scheme for “split-capacitor” converter topology is simple and also capable of maintaining the compensated line currents balanced, irrespective of unbalancing in the source voltages & deviation in the capacitor voltages. The results presented in MATLAB-SIMULINK software in this paper clearly reflect the effectiveness of the proposed APF to meet the IEEE-519 standard recommendations on harmonic levels.
Novel hybrid methods applied for the numerical simulation of three-phase biotechnological flows
Energy Technology Data Exchange (ETDEWEB)
Diez Robles, Lucia
2009-07-01
Granular Activated Sludge (GAS) is na novel biological secondary treatment of wastewater which presents multiple advantages with respect to Conventional Activated Sludge (CAS). For fluid mechanical analysis of the bioreactor in which GAS is cultivated, two strategies are adopted: numerical analysis which is carried out in the present thesis and optical in situ measurements which validate the numerical results. The Eulerian-Eulerian multi-fluid approach does not offer a satisfactory description of the three-phase flow as there is a lack of appropriate mathematical models and the solution of the equation systems is problematic. Hybrid methods are here developed in order to complement the classical numerical techniques. These improve the convergence of the numerical simulation, generate results more in accordance with the experimental results and reduce the CPU time required for the calculations. An additional momentum exchange between the dispersed phases is also proposed for the consideration of the four-way coupling case. (orig.)
Directory of Open Access Journals (Sweden)
Zulkarnain Lubis
2009-01-01
Full Text Available Problem statement: With emphasis on a cleaner environment and efficient operation, vehicles today rely more and more heavily on electrical power generation for success. Approach: Mathematical modeling the components of the HEV as the three phase induction motor couple to DC motor in hybrid electric vehicle was introduced. The controller of Induction Motor (IM was designed based on input-output feedback linearization technique. It allowed greater electrical generation capacity and the fuel economy and emissions benefits of hybrid electric automotive propulsion. Results: A typical series hybrid electric vehicle was modeled and investigated. Conclusion: Various tests, such as acceleration traversing ramp and fuel consumption and emission were performed on the proposed model of 3 phase induction motor coupler DC motor in electric hybrid vehicles drive.
Power Controllability of Three-phase Converter with Unbalanced AC Source
DEFF Research Database (Denmark)
Ma, Ke; Chen, Wenjie
2015-01-01
Three-phase DC-AC power converters suffer from power oscillation and overcurrent problems in case of unbalanced AC source voltage that can be caused by grid/generator faults. Existing solutions to handle these problems are properly selecting and controlling the positive and negative sequence currents. In this work a new series of control strategies which utilize the zerosequence components are proposed to enhance the power control ability under this adverse condition. It is concluded that by introducing proper zero sequence current controls and corresponding circuit configurations, the power converter can enable more flexible control targets, achieving better performances in the delivered power and load current when suffering from unbalanced AC voltage.
Modeling of a three-phase reactor for bitumen-derived gas oil hydrotreating
Scientific Electronic Library Online (English)
R., Chacón; A., Canale; A., Bouza; Y., Sánchez.
2012-03-01
Full Text Available A three-phase reactor model for describing the hydrotreating reactions of bitumen-derived gas oil was developed. The model incorporates the mass-transfer resistance at the gas-liquid and liquid-solid interfaces and a kinetic rate expression based on a Langmuir-Hinshelwood-type model. We derived thre [...] e correlations for determining the solubility of hydrogen (H2), hydrogen sulfide (H2S) and ammonia (NH3) in hydrocarbon mixtures and the calculation of the catalyst effectiveness factor was included. Experimental data taken from the literature were used to determine the kinetic parameters (stoichiometric coefficients, reaction orders, reaction rate and adsorption constants for hydrodesulfuration (HDS) and hydrodenitrogenation (HDN)) and to validate the model under various operating conditions. Finally, we studied the effect of operating conditions such as pressure, temperature, LHSV, H2/feed ratio and the inhibiting effect of H2S on HDS and NH3 on HDN.
Bhat, Abdul Hamid; Langer, Nitin
2014-12-01
In this paper, parameter plane synthesis of a three-phase neutral-point clamped bidirectional rectifier has been performed. The converter involves one outer-loop PI voltage controller and two inner-loop PI current controllers for the closed-loop control. D-partition technique has been employed for the precise design of the voltage controller. An experimental prototype of the converter has been developed, and the experimental investigation of the converter performance in closed loop has been carried out. DSP DS1104 of dSPACE has been used for real-time implementation of the designed controller. The converter gives a very good performance in steady state and dynamic state (for rectification as well as inversion modes of operation) using the designed controller parameters.
Radwaste Three Phase Plan: backfit modifications and evaluations at San Onofre units 2 and 3
International Nuclear Information System (INIS)
The Radwaste Three Phase Plan was developed to provide a comprehensive, integrated program to perform recommended modifications to the radwaste systems at San Onofre Nuclear Generating Station, Units 2 and 3. The Radwaste Task Force was also created to ensure operation of radwaste systems as described in the FSAR and consistent with the established operating philosophy. The modifications are required due to the impact of changes in burial site disposal requirements and additional regulatory requirements, the need to correct design and operation inadequacies discovered during start-up and initial plant operation, and to increase the operational flexibility of the radwaste systems. The changes recommended in Phase I are well into various stages of engineering and construction; Phase II evaluations are now underway; and the final scope of Phase III tasks will be identified as the Phase II evaluations are completed
Four quadrant control circuit for a brushless three-phase dc motor
Nola, Frank J. (inventor)
1987-01-01
A control circuit is provided for a brushless three-phase dc motor which affords four quadrant control from a single command. The control circuit probes acceleration of the motor in both clockwise and counterclockwise directions and braking and generation in both clockwise and counterclockwise directions. In addition to turning on individual transistors of the transistor pairs connected to the phase windings of the motor for 120 deg periods while the other transistor of that pair is off, the control circuit also provides, in a future mode of operation, turning the two transistors of each pair on and off alternately at a phase modulation frequency during such a 120 deg period. A feedback signal is derived which is proportional to the motor current and which has a polarity consistent with the command signal, such that negative feedback results.
A Compact Three-Phase Single-Input/Dual-Output Matrix Converter
DEFF Research Database (Denmark)
Liu, Xiong; Wang, Peng
2012-01-01
This paper presents a novel matrix converter with one ac input and two ac outputs. The presented topology is based on the traditional indirect matrix converter, but with its rear-end six-switch inverter replaced by a compact nine-switch inverter. With only three extra switches added, the proposed converter can produce two sets of three-phase ac outputs, whose amplitudes, frequencies, and phases can appropriately be regulated. Features such as sinusoidal input and outputs, unity input power factor and minimum commutation count are all retained by the proposed topology, despite having an additional output. Its modulation is realized by the computationally less intensive carrier-based method, whose unique carrier requirements can easily be managed within a programmable logic device. Mathematical proof for validating sinusoidal input and outputs achieved by this modulation technique is also discussed, before being verified in simulation and experimentally, together with other findings.
Modeling of a three-phase reactor for bitumen-derived gas oil hydrotreating
Directory of Open Access Journals (Sweden)
R. Chacón
2012-03-01
Full Text Available A three-phase reactor model for describing the hydrotreating reactions of bitumen-derived gas oil was developed. The model incorporates the mass-transfer resistance at the gas-liquid and liquid-solid interfaces and a kinetic rate expression based on a Langmuir-Hinshelwood-type model. We derived three correlations for determining the solubility of hydrogen (H2, hydrogen sulfide (H2S and ammonia (NH3 in hydrocarbon mixtures and the calculation of the catalyst effectiveness factor was included. Experimental data taken from the literature were used to determine the kinetic parameters (stoichiometric coefficients, reaction orders, reaction rate and adsorption constants for hydrodesulfuration (HDS and hydrodenitrogenation (HDN and to validate the model under various operating conditions. Finally, we studied the effect of operating conditions such as pressure, temperature, LHSV, H2/feed ratio and the inhibiting effect of H2S on HDS and NH3 on HDN.
Choudhury, A.; Geeta, M.; Nestler, B.
2013-01-01
We utilize a quantitative phase-field model to simulate three-phase eutectic growth and the oscillatory instabilities at large spacings. We analyze the effect of symmetry in the selection of the oscillatory mode for the case of directional solidification. Going further from our previous article (Choudhury A. et al., Phys. Rev. E, 83 (2011) 051608), we manipulate the symmetry elements in a given configuration through the use of solid-solid anisotropy. Characteristic modes are compared between the case of isotropic surface energies and those retrieved in the presence of solid-solid anisotropy. We end with certain general arguments with regards to the growth rate of oscillatory modes and symmetry elements of the obtained microstructure depending on the symmetry elements of the starting configuration.
Power loss benchmark of nine-switch converters in three-phase online-UPS application
DEFF Research Database (Denmark)
Qin, Zian; Loh, Poh Chiang
2014-01-01
Three-phase online-UPS is an appropriate application for the nine-switch converter, where its high voltage stress of the power device caused by the reduced switch feature can be relieved significantly. Its power loss and loss distribution still have the flexibility from the control point of view due to its asymmetrical structure, which are critical indicators for efficiency and reliability. They are therefore analyzed mathematically in this paper, in terms of conduction loss and switching loss. Moreover, various modulation strategies that fit for the nine-switch converter as well as parameters like modulation index and phase angle of the load are taken into account. The benchmark of power loss will become a guidance for the users to make best use of the advantages and bypass the disadvantages of nine-switch converters. The results are finally verified on a 1.5 kW prototype.
Modeling of a three-phase reactor for bitumen-derived gas oil hydrotreating
International Nuclear Information System (INIS)
A three-phase reactor model for describing the hydrotreating reactions of bitumen-derived gas oil was developed. The model incorporates the mass-transfer resistance at the gas-liquid and liquid-solid interfaces and a kinetic rate expression based on a Langmuir-Hinshelwood-type model. We derived three correlations for determining the solubility of hydrogen (H2), hydrogen sulfide (H2S) and ammonia (NH3) in hydrocarbon mixtures and the calculation of the catalyst effectiveness factor was included. Experimental data taken from the literature were used to determine the kinetic parameters (stoichiometric coefficients, reaction orders, reaction rate and adsorption constants for hydrodesulfuration (HDS) and hydrodenitrogenation (HDN)) and to validate the model under various operating conditions. Finally, we studied the effect of operating conditions such as pressure, temperature, LHSV, H2/feed ratio and the inhibiting effect of H2S on HDS and NH3 on HDN. (author)
High Performance Speed Sensorless Control of Three-Phase Induction Motor Based on Cloud Computing
Directory of Open Access Journals (Sweden)
Z. M. Salem
2012-10-01
Full Text Available Induction motor is a cast of alternating current motor where charge endures allotted to the rotor close-at-hand deputation of conductive charge. These motors are broadly applied in industrial claim due to they are arduous along with adhere no contacts. The speed controller of deltoid phase induction motor is applied to alleviate the aberration of speed. The central constructivist of this paper is to accrue the performance of speed sensorless control of three phase induction motor. To increase its performance, this paper presents a modified method for speed controller of an indirect vector-controlled induction motor drive using cloud computing technique. Our methodology depends on speed sensorless scheme to obtain the speed signal feedback; the speed estimator is based on model reference adaptive control that uses the stator current and rotor flux as state variables for estimating the speed. In this method, the stator current error is represented as a function of first degree of the estimated speed error. An analysis and simulation of the tried algorithm is birthed and applied easing a TMS320C31 floating-point notational alert Processor. And accumulate the action of the three phase induction motor we conceived our appraisals affixed to the accountant based on cloud computing tactics. This intelligent policy uses the guidelines of the speed controller efficiently. Simulation and experimental results depicted that the motor speed is decelerated articulately to destine its illusion apprise without above and inferior smack and with about zero steady state error. The apprised accelerate alert and its dispatching buoy amassed off line from burlesque. After effects display an advantageous affinity among the accounted speed alert and it's dispatching allocated as well as aped speed flares
Directory of Open Access Journals (Sweden)
Eduardo Pérez Lobato
2006-08-01
Full Text Available This paper presents the use of a microcontroller to demodulate two Pulse Width Modulated (PWM signals which are being generated by a digital accelerometer, to obtain their pulse widths and transmit them serially to a parallel port of a general purpose computer.Esta publicación presenta el uso de un microcontrolador para demodular dos seńales PWM que están siendo generadas por un acelerómetro digital, obtener sus anchos y enviarlas en forma serial al puerto paralelo de un computador de propósitos generales.
Scientific Electronic Library Online (English)
Eduardo, Pérez Lobato; Marcelo, Muńoz Tapia; Jorge, Ramírez Fernández.
2006-08-01
Full Text Available Esta publicación presenta el uso de un microcontrolador para demodular dos seńales PWM que están siendo generadas por un acelerómetro digital, obtener sus anchos y enviarlas en forma serial al puerto paralelo de un computador de propósitos generales. [...] Abstract in english This paper presents the use of a microcontroller to demodulate two Pulse Width Modulated (PWM) signals which are being generated by a digital accelerometer, to obtain their pulse widths and transmit them serially to a parallel port of a general purpose computer. [...
Wang, Ping-Chieh; Uang, Chii-Maw; Hong, Yi-Jian; Ho, Zu-Sheng
2011-10-01
Saving energy, White-light LED plays a main role in solid state lighting system. Find the best energy saving driven solution is the engineer endless hard work. Besides DC and AC driving, LED using Pulse Width Modulation (PWM) operation is also a valuable research topic. The most important issue for this work is to find the drive frequency and duty for achieving both energy saving and better feeling on the human vision sensation. In this paper, psychophysics of human vision response to the lighting effect, including Persistence of vision, Bloch's Law, Broca-Sulzer Law, Ferry-Porter Law, Talbot-Plateau Law, and Contrast Sensitivity, will be discussed and analyzed. From the human vision system, we found that there are three factors: the flash sensitivity, the illumination intensity and the background environment illumination, that are used to decide the frequency and duty of the PWM driving method. A set of controllable LED lamps with adjustable frequency and duty is fitted inside a non-closed box is constructed for this experiment. When the background environment illumination intensity is high, the variation of the flash sensitivity and illumination intensity is not easy to observe. Increasing PWM frequency will eliminate flash sensitivity. When the duty is over 70%, the vision sensitivity is saturated. For warning purpose, the better frequency range is between 7Hz to 15Hz and the duty cycle can be lower down to 70%. For general lighting, the better frequency range is between 200Hz to 1000Hz and the duty cycle can also be lower down to 70%.
Scientific Electronic Library Online (English)
LIVIU S., BOCII; VALENTIN, MULLER.
2013-06-01
Full Text Available Este documento estabelece um modelo matemático de máquina de induçăo conectado a um inversor de frequęncia necessário para ajustar o motor de acionamento elétrico. O modelo matemático baseado na Teoria de Park permite a análise de todo o espectro (carro elétrico com inversor de frequęncia) para diri [...] gir o ônibus elétrico feito em ASTRA Bus Arad (Romęnia). Para remover harmônicas de ordem mais alta, a forma de onda da tensăo de alimentaçăo PWM é utilizado, definido no caso geral. Características de funcionamento do motor de acionamento elétrico săo definidas para frequęncia sub-nominal (f Abstract in english This paper establishes a mathematical model of induction machine connected to a frequency inverter necessary to adjust the electric motor drive. The mathematical model based on the Park's theory allows the analysis of the whole spectrum (electric car – frequency inverter) to drive the electric troll [...] ey bus made on ASTRA Bus Arad (Romania). To remove higher order harmonics, the PWM waveform of supply voltage is used, set in the general case. Operating characteristics of electric motor drive are set to sub-nominal frequency (f
Directory of Open Access Journals (Sweden)
LIVIU S. BOCÎI
2013-06-01
Full Text Available This paper establishes a mathematical model of induction machine connected to a frequency inverter necessary to adjust the electric motor drive. The mathematical model based on the Park's theory allows the analysis of the whole spectrum (electric car – frequency inverter to drive the electric trolley bus made on ASTRA Bus Arad (Romania. To remove higher order harmonics, the PWM waveform of supply voltage is used, set in the general case. Operating characteristics of electric motor drive are set to sub-nominal frequency (f Bele 2007.Este documento estabelece um modelo matemático de máquina de induçăo conectado a um inversor de frequęncia necessário para ajustar o motor de acionamento elétrico. O modelo matemático baseado na Teoria de Park permite a análise de todo o espectro (carro elétrico com inversor de frequęncia para dirigir o ônibus elétrico feito em ASTRA Bus Arad (Romęnia. Para remover harmônicas de ordem mais alta, a forma de onda da tensăo de alimentaçăo PWM é utilizado, definido no caso geral. Características de funcionamento do motor de acionamento elétrico săo definidas para frequęncia sub-nominal (f
Voltage peaks of low voltage induction motors due to PWM inverter supply
Kawkabani, B.; Simond, J.-J.; Kehtari, F.
1995-01-01
In industrial variable speed drives, the supply of low voltage induction motors by IGBT-PWM inverters through screened cables may cause dangerous over-voltage surges at the motors terminals. These voltage peaks of about twice the de link voltage, with a short rise time of about 200 nsec, increase the armature insulation stress and may damage the motor insulation. The prsent study provides a theoretical approach to this matter and is completed by tests performed on two 3 and 7.5 kW drives, wit...
A new ZCZVT commutation cell for PWM DC-AC converters
Scientific Electronic Library Online (English)
C. M. de O., Stein; H. L., Hey; J. R., Pinheiro; H., Pinheiro; H. A., Gründling.
2004-06-01
Full Text Available Este artigo propőe um novo circuito auxiliar para inversores PWM que permite que a entrada em conduçăo e o bloqueio das chaves principais ocorram com corrente e tensăo nulas. A entrada em conduçăo das chaves principais com corrente nula reduz os efeitos indesejados referentes ŕs indutâncias intrínse [...] cas do circuito. Uma vez que o circuito auxiliar controla o di/dt e o dv/dt, as perdas de recuperaçăo reversa dos diodos principais săo minimizadas. A célula de comutaçăo ZCZVT, ativada somente durante as comutaçőes, é localizada fora do caminho principal do fluxo de potęncia. Adicionalmente, as chaves auxiliares comutam em ZCS e usam o mesmo sinal de terra das chaves principais superiores. Devido ŕ açăo do circuito auxiliar, as perdas de comutaçăo săo praticamente eliminadas. A operaçăo com comutaçőes suaves é garantida para toda a faixa de carga sem mudanças na estratégia de comando. A operaçăo de um inversor ponte-completa ZCZVT PWM é analizada e, baseado nesta análise, é proposto um procedimento de projeto do circuito auxiliar. Para demonstrar a viabilidade do circuito de comutaçăo proposto, săo apresentados resultados experimentais obtidos em um protótipo. Abstract in english This paper proposes a new auxiliary commutation cell for PWM inverters that allows the main switches to be turned on and off at zero voltage and zero current. The main switches zero current turn-on reduces the undesired effects of parasitic inductances related to the circuit layout. The main diodes [...] reverse recovery losses are minimized since di/dt and dv/dt are controlled. The ZCZVT commutation cell is located out of the main power path of the converters and is activated only during switching transitions. Additionally, the auxiliary switches are turned on and off at ZCS and use the same ground signals of the upper main switches. The commutation losses are practically reduced to zero. Soft switching operation is guaranteed for full load range without changes in command strategy. The operation of the ZCZVT PWM full-bridge DC-AC Converter is analyzed and an auxiliary commutation cell design procedure based on the analysis is proposed. Experimental results are presented to demonstrate the feasibility of the proposed commutation cell.
Elimination of output voltage oscillations in DC-DC converter using PWM with PI controller
Sreenivasappa Veeranna Bhupasandra; Udaykumar Yaragatti
2010-01-01
In this paper the SIMULINK model of a PWM controlled DC-DC converter is modeled using switching function concept to control the speed of the DC motor. The presence of the voltage oscillation cycles due to higher switching frequency in the DC-DC converter is identified. The effect of these oscillations on the output voltage of the converter, Armature current, Developed torque and Speed of the DC motor is analyzed. In order to minimize the oscillation cycles the PI controller is proposed in the...
Design of a ZVS PWM inverter for a brushless DC motor in an EMA application
Bell, J. Brett; Nelms, R. M.; Shepherd, Michael T.
1993-01-01
The Component Development Division of the Propulsion Laboratory at Marshall Space Flight Center (MSFC) is currently investigating the use of electromechanical actuators for use in space transportation applications such as Thrust Vector Control (TVC). These high power servomechanisms will require rugged, reliable, and compact power electronic modules capable of modulating several hundred amperes of current at up to 270 Vdc. This paper will discuss the design and implementation of a zero-voltage-switched PWM (Pulse Width Modulation) inverter which operates from a 270 Vdc source at currents up to 100 A.
A Passivity-based Control for DC Motor Drive System with PWM
Directory of Open Access Journals (Sweden)
Honghua Wang
2012-12-01
Full Text Available This paper investigates a passivity-based control (PBC for DC Motor drive system with PWM. In the paper, the port-controlled Hamiltonian system with dissipation (PCHD model of the system is built and the interconnection and damping assignment passivity-based control (IDA-PBC method is used for the design of the controller. The system simulation model is built based on MATLAB/Simulink and the simulation results validate that the DC Motor drive system based on PBC controller has excellent dynamic performances such as robustness and transient response, compared with the traditional PI controller.
Directory of Open Access Journals (Sweden)
H. Ben Attia Sethom
2008-06-01
Full Text Available This paper presents a method to detect and localize intermittent misfiring default on a Pulse Width Modulation (PWM inverter supplying a squirrel cage induction machine. The proposed method is based on the Discrete Wavelet Transform (DWT technique to analyse stator current signals. The intermittent misfiring detection is performed thanks to the Daubechies wavelet mother in high frequency bands of the stator current signal. The localisation of the phase where the intermittent misfiring occurs is determined by a statistic approach. This approach is based on the computing of mean power characteristics of the detail signals which are obtained from the stator current wavelet decomposition.
Efficiency studies of hysteretic and PWM boost converters: Controller- and battery-type effects
Sanchez, Juan Herminio, III
A continuous conduction boost converter is studied as a function of four battery types and two controllers. The battery types are alkaline, NiCd, NiMH, and sealed lead-acid. The controllers implement voltage-mode pulse-width modulation (PWM) and hysteretic current-mode (HCM) control schemes, respectively. The boost converter is designed to produce an output of 3W at 12V DC with battery voltages ranging from 6V to 3V. The study focuses on converter efficiency as affected by battery type, controller type, and the combined effects of battery type and controller type. Computer simulations predict and experimental results verify that differences in converter efficiency between the different battery types are due to differences in capacity, current-handling capabilities, and sustained voltage levels. The HCM controller uses a control scheme, in which the switching frequency decreases as battery voltage decreases, resulting in lower MOSFET switching losses. This effect partially compensates for the increased conduction losses in converter components as more current is drawn from batteries at lower input voltages. The PWM controller has a fixed switching frequency (50 kHz) and both its switching and conduction losses increase with decreasing input voltage. Efficiency levels of 88% are achieved for higher battery voltages, decreasing to 80% for lower voltages. A difference of up to 2% higher efficiency is observed in the HCM over the PWM. The major power losses are due to the combination of the inductor's ESR and the resistance of the wire used to increase the Hall-effect current sensor turns-ratio (increasing from 400mW to 1.2W). Simulations predict that in the absence of this resistance, efficiency levels of 95% can be achieved. Conduction losses through the rectifier are in the range of 40mW to 50mW for both controllers. MOSFET switching losses amount to 50mW for both controllers at high input voltages, increasing to 100mW for the PWM, but only to 65mW for the HCM at lower input voltages. The advantage of the proposed HCM scheme is expected to have a larger impact on converter efficiency at higher frequencies where switching losses are higher.
Performance of the Push-Pull LLC Resonant and PWM ZVS Full Bridge Topologies
S. RAMA REDDY; Deepak Kumar Nayak
2011-01-01
The soft switched PWM ZVS full bridge DC to DC converter and push-pull type LLC series resonant converter are compared for use in low output voltage power supply applications. It is shown that push-pull type LLC series resonant converter takes on the desirable characteristics of the conventional push-pull converter and LLC series resonant converter. Push-pull type has less conduction loss than that of full bridge converter. Analyses and simulation shows that for low power applications require...
Comparison of Performance of VSI and Z-Source Inverter for Space Vector PWM
Directory of Open Access Journals (Sweden)
E. Sai Prateek
2014-05-01
Full Text Available Z-Source Inverters have the ability to boost the dc link voltage, thus increasing the output ac voltage beyond the values reached by conventional inverters. The enhanced ratio from ac output voltage to dc link voltage is possible due to an impedance network connected between the dc power supply and the main converter. The space vector pulse width modulation techniques gives more dc bus utilisation and low harmonics than other pulse width modulation techniques. In this paper space vector pwm is implemented for conventional VSI and Zsource inverter. The results are supported by SIMULINK simulation
Scientific Electronic Library Online (English)
Pedro A, Vargas V; José G, Contreras.
2007-08-01
Full Text Available Este artículo presenta el análisis de la conmutación a cero voltaje (ZVS) y conmutación a cero corriente (ZCS) de un convertidor AC-DC trifásico con una sola etapa de procesamiento de potencia. Se deriva un criterio para activar los transistores del inversor DC-AC en puente completo (FB), utilizando [...] modulación de ancho de pulso (PWM) por desplazamiento de fase, con el propósito de lograr la conmutación ZVS de la rama en adelanto del FB, y el ajuste del voltaje DC de salida. La conmutación ZCS de la rama en atraso del FB, se conseguirá utilizando un circuito resonante auxiliar simple. Un análisis matemático y gráfico permite obtener un criterio para ajustar el tiempo muerto de la rama en adelanto y la selección de los componentes del circuito resonante auxiliar. Las características del convertidor fueron verificadas, mediante simulación y resultados experimentales para una fuente trifásica conmutada de 1,5 kW, frecuencia de conmutación de 50 kHz y voltaje de salida DC de 60V Abstract in english In this paper, analysis of a Zero Voltage-Current Switching (ZVCS) with a single stage of power processing converter is presented. A drive strategy for the activation of Full Bridge (FB) inverter using Phase Shift (FS) pulse width modulation (PWM), is describe in order to achieve ZVS in a leading le [...] g and adjustment of the output DC voltage. A simple auxiliary circuit is used to achieve ZCS in a lagging leg. A mathematical and graphic analysis is made in order to obtain a approach to adjust the die time of a leading leg and the selection of the components of the auxiliary circuit. Experimental results are included for a 1.5kW, 50kHz and 60V output three phase AC-DC converter which confirms the performance of de proposed topology
Coupled LBM-DEM Three-phase Simulation on Gas Flux Seeping from Marine Sediment
Kano, Y.; Sato, T.
2014-12-01
One of the main issues of the geological storage of CO2 under the seabed is a risk of CO2 leakage. Once CO2seeps into the ocean, it rises in water column dissolving into seawater, which results in the acidification of seawater and/or returning to the air. Its behaviour significantly depends on flow rate and bubble size (Kano et al., 2009; Dewar et al., 2013). As for porous media, bubble size is generally predicted through simple force balance based on flow rate, surface tension and channel size which is estimated by porosity and grain size. However, in shallow marine sediments, grains could be mobilised and displaced by buoyant gas flow, which causes distinctive phenomena such as blow-out or formation of gas flow conduit. As a result, effective gas flux into seawater can be intermissive, and/or concentrated in narrow area (QICS, 2012; Kawada, 2013). Bubble size is also affected by these phenomena. To predict effective gas flux and bubble size into seawater, three-phase behaviour of gas-water-sediment grains should be revealed. In this presentation, we will report the results of gas-liquid-solid three-phase simulations and their comparisons with experimental and observation data. Size of solid particles is based on grain size composing marine sediments at some CCS project sites. Fluid-particle interactions are solved using the lattice Boltzmann method (LBM), while the particle-particle interactions are treated by coupling with the Discrete Element method (DEM). References: Dewar, M., Wei, W., McNeil, D., Chen, B., 2013. Small-scale modelling of the physiochemical impacts of CO2leaked from sub-seabed reservoirs or pipelines within the North Sea and surrounding waters. Marine Pollution Bulletin 73(2), 504-515. Kano, Y., Sato, T., Kita, J., Hirabayashi, S., Tabeta, S., 2009. Model prediction on the rise of pCO2 in uniform flows by leakage of CO2purposefully stored under the seabed. Int. J. Greenhouse Gas Control, Vol. 3(5), 617-625. Kawada, R. 2014. A study on the mechanism which determines the size of bubbles seeping from sand sediment. Graduation thesis. Faculty of Engineering, The University of Tokyo. (in Japanese). QICS, 2012. QICS: Quantifying and Monitoring Potential Ecosystem Impacts of Geological Carbon Storage. (accessed Aug.06.14)
Improved Design Methods for Robust Single- and Three-Phase ac-dc-ac Power Converters
DEFF Research Database (Denmark)
Qin, Zian
2015-01-01
As the ac-dc-ac converters are widely used interfaces in energy conversion system, they play an important role in reducing cost of energy. Therefore, the objective of this thesis is to study and propose advanced design for robust ac-dc-ac converters, where the voltage stress, the efficiency, the energy density, the cost, the loss distribution, and thermal performance of the converters will all be taken into account. The thesis contains four parts and seven chapters. The first part – “Preamble” contains only Chapter 1, which presents the introduction and motivation of the whole project as well as the background, the emerging challenges, and the structure of the thesis. The second part – “Single-Phase AC-DC-AC converters” covers three chapters. Chapter 2 and Chapter 3 propose new modulation methods for single-phase B6 and H6 converters, respectively, to retain the same DC-link voltage with two full-bridges connected back-to-back, and at the same time improve the thermal distribution between the switches, the harmonics, and hence the control flexibility. Chapter 4 studies the active power decoupling methods for single-phase inverters or rectifiers, which is similar to the single-phase ac-dc-ac converter. With active power decoupling the ripple power in the converter can be compensated in a more efficient and more compact way. The third part – “Three-Phase AC-DC-AC Converters” is composed of two chapters. Chapter 5 studies the nine-switch converter, which is a reduced switch version of two three-phase full-bridges connected back-to-back. Application criteria of the nine-switch converter are investigated to reduce the relatively high stress introduced by the less number of switches. Chapter 6 proposes a rotating speed controller design method to improve the thermal loading of the wind power converter in a system level. The fourth part – “Conclusions” has only Chapter 7, which gives the conclusion and the contributions in the thesis as well as the proposals for the future work. Several approaches are proposed in this thesis to achieve a robust design of ac-dc-ac power converters including: 1. new modulation schemes of single-phase B6 and H6 converters for improved performance, 2. an optimal active power decoupling approach for kW-scale single-phase converters to achieve high power density and high efficiency, 3. application criteria of nine-switch converters for improved performance in terms of loss and temperature, 4. a new rotating speed controller design method for power levelling of wind power converters.
Ribereau, P.; Guillou, A.; Naveau, P.
2008-12-01
Since the pioneering work of Landwehr et al. (1979), Hosking et al. (1985) and their collaborators, the Probability Weighted Moments (PWM) method has been very popular, simple and efficient to estimate the parameters of the Generalized Extreme Value (GEV) distribution when modeling the distribution of maxima (e.g., annual maxima of precipitations) in the Identically and Independently Distributed (IID) context. When the IID assumption is not satisfied, a flexible alternative, the Maximum Likelihood Estimation (MLE) approach offers an elegant way to handle non-stationarities by letting the GEV parameters to be time dependent. Despite its qualities, the MLE applied to the GEV distribution does not always provide accurate return level estimates, especially for small sample sizes or heavy tails. These drawbacks are particularly true in some non-stationary situations. To reduce these negative effects, we propose to extend the PWM method to a more general framework that enables us to model temporal covariates and provide accurate GEV-based return levels. Theoretical properties of our estimators are discussed. Small and moderate sample sizes simulations in a non-stationary context are analyzed and two brief applications to annual maxima of CO2 and seasonal maxima of cumulated daily precipitations are presented.
Conversores de freqüencia VSI-PWM submetidos a afundamentos temporários de tensăo ("voltage sags")
Scientific Electronic Library Online (English)
Paulo C. A., Leăo; José C. de, Oliveira; Kleiber D., Rodrigues.
2003-03-01
Full Text Available Este artigo tem por objetivo analisar a interdependęncia entre a operaçăo de conversores de freqüęncia tipo VSI-PWM e uma das manifestaçőes mais comuns para a perda de qualidade de um suprimento elétrico, qual seja, a ocorręncia do fenômeno denominado por afundamento temporário de tensăo ou "voltage [...] sag". Săo apresentados resultados de simulaçőes, realizadas no Simulador Saber, de um sistema típico submetido a afundamentos de tensőes simétricos e assimétricos. Resultados de ensaios em laboratório também săo fornecidos com vistas ŕ validaçăo dos resultados computacionais. Aspectos relacionados com a capacidade "ride-through" dos conversores e correspondentes arranjos de proteçăo săo também considerados. Abstract in english This paper aims at analyzing the relationship between VSI-PWM frequency converters behavior and a very common type of power quality disturbance, i.e. the well known voltage sag effect. By using a proper model into the Saber Simulator, simulation results for a typical system under symmetrical and asy [...] mmetrical sag phenomenon conditions are shown. Experimental results are also given in order to validate the computational behaviour. The converter ride-through capability as well as the protection units interaction are also included into the analysis.
Control of synchrotron electromagnet power supply using a current type PWM converter
International Nuclear Information System (INIS)
Together with actualization of large volume semiconductor switching element, direct current (DC) source for electromagnet excitation of an accelerator is changing from thyristor rectification source to PWM converter source using GTO and IGBT, which is a direct converter of alternating current (AC) power to DC power as well as the thyristor rectification source in difference from conventional DC-DC converter. And that, it has an advantage that it can not only convert AC power to DC one, but also compensate loss factor and harmonic wave of the converter simultaneously and actualize a precise control because of its possibility of setting short sampling time. At present a basic experiment was carried out under consideration on application of a current type PWM converter to a source for synchrotron electromagnet excitation. And, two kinds of comparative investigation on two freedoms PI control system and repeating control system with minor loop were carried out. As a result, it was found that as a problem on follow-delay against a target value could be compensated more easily than two freedoms control system using a target value filter could, compensation of outer disturbance such as source voltage variation, load variation, and so forth, and that a repeating control system with minor loop could compensate a follow-delay problem at each repeating, and also compensate outer disturbance on source voltage and load variations due to minor loop. (G.K.)
Vector control of three-phase induction motor using artificial intelligent technique
Directory of Open Access Journals (Sweden)
Arunima Dey
2009-06-01
Full Text Available The controllability of torque in an induction motor without any peak overshoot and less ripples with good transient and steady state responses form the main criteria in the designing of a controller. Though PI controller is able to achieve these but with certain drawbacks as the gains can not be increased beyond certain limit so as to have an improved response. Moreover, it introduces non linearity into the system making it more complex for analysis. Also it deteriorates the controller performance. With the advent of artificial intelligent techniques, these drawbacks can be mitigated. One such technique is the use of Fuzzy Logic in the design of controller either independently or in hybrid with PI controller. This paper proposes a unique set of fuzzy logics for the speed controller design to be used in vector controlled three phase induction motor. The results obtained from the model using proposed Fuzzy Logic Controller and PI Controller are compared. It can be concluded that use of Fuzzy logic improves and smoothens out the ripples in the motor torque and stator currents. It also facilitates in limiting the magnitude of the torque and current values within the specified range in any kind of disturbance, either provided by the speed removal or by sudden application and removal of load torque. This has been verified through the simulation results of the model built completely in a MATLAB/SIMULINK environment.
Modular Plug’n’Play Control Architectures for Three-phase Inverters in UPS Applications
DEFF Research Database (Denmark)
Zhang, Chi; Guerrero, Josep M.
2015-01-01
In this paper a control strategy for the parallel operation of three-phase inverters in a modular online uninterruptable power supply (UPS) system is proposed. The UPS system is composed of a number for DC/ACs with LC filter connected to the same AC critical bus and an AC/DC that forms the DC bus. The proposed control is designated in two layers, individual layer and recovery layer. In individual layer, virtual impedance concept is employed in order to achieve active power sharing while individual reactive power is calculated to modify output voltage phases to achieve reactive power sharing among different modules. Recovery layer is mainly responsible for guaranteeing synchronization capability with the utility and voltage recovery. With the proposed control, improved voltage transient performance can be achieved and also DC/AC modules are allowed to be plugged in and out flexibly while controlling the AC critical bus voltage. Detailed control architecture, regarding individual layer and recovery layer, are presented in this paper. Also an experimental setup was built to validate the proposed control approach under several scenarios-case study.
Dynamics of double emulsion break-up in three phase glass capillary microfluidic devices.
Nabavi, Seyed Ali; Gu, Sai; Vladisavljevi?, Goran T; Ekanem, Ekanem E
2015-07-15
Pinch-off of a compound jet in 3D glass capillary microfluidic device, which combines co-flowing and countercurrent flow focusing geometries, was investigated using an incompressible three-phase axisymmetric Volume of Fluid-Continuum Surface Force (VOF-CSF) numerical model. The model showed good agreement with the experimental drop generation and was capable of predicting formation of core/shell droplets in dripping, narrowing jetting and widening jetting regimes. In dripping and widening jetting regimes, the presence of a vortex flow around the upstream end of the necking thread facilitates the jet break-up. No vortex flow was observed in narrowing jetting regime and pinch-off occurred due to higher velocity at the downstream end of the coaxial thread compared to that at the upstream end. In all regimes, the inner jet ruptured before the outer jet, preventing a leakage of the inner drop into the outer fluid. The necking region moves at the maximum speed in the narrowing jetting regime, due to the highest level of shear at the outer surface of the thread. However, in widening jetting regime, the neck travels the longest distance downstream before it breaks. PMID:25828435
Promoting Professional Development: Three Phases of Articulation in Nursing Education and Practice
Directory of Open Access Journals (Sweden)
Sister Rosemary Donley
2008-09-01
Full Text Available In this article the authors present the evolution of career ladders in nursing education and practice and discuss their development, maturation, and institutionalization in three phases over a span of forty years. In phase one, academic career ladders were spiral staircases, complex, confusing, and poorly articulated entry and exit pathways. Phase two saw the maturation of career ladders across all levels of nursing education and practice. In phase three, academic and clinical career ladders, built upon theoretical perspectives, have enriched academic programs and clinical practice and increasingly are being integrated into the curriculum, clinical advancement programs, and the magnet hospital movement. The authors conclude by discussing continuing questions, such as the amount of clinical experience needed in an educational program and the amount of clinical practice needed before seeking an advanced degree. They highlight the need for more research and dialogue about the amount, type, and measurement of clinical work and argue that these studies are needed to better inform decisions about professional legislation, accreditation, certification, education, healthcare outcomes, and future-oriented career ladders.
Determination of nickel, vanadium and iron in crude oil by three-phase plasma arc spectrometry
International Nuclear Information System (INIS)
Three-phase plasma arc (TPPA) with ultrasonic nebulizer is developed for simultaneous determination of trace elements in crude oil samples. Ultrasonic nebulizer is used instead of pneumatic nebulizer in order to minimize the problems caused by the oil viscosity during the operation. This system was used for determination of some trace elements (V, Ni, and Fe) in a crude oil samples. Methyl isobutyl ketone (MIBK) was used to dilute the oil samples. The TPPA instrument offers several advantages including a low cost power supply with no radio frequency, linear dynamic ranges from 4 to 5 of orders of magnitude, and detection limits (0.121, 0.313 and 0.242 (?g/ml) for Ni, V and Fe respectively. The average concentrations were 31 ± 0.45 (?g/ml) for Ni, 40 ± 0.88 (?g/ml) for V and 8 ± 0.74 (?g/ml) for Fe at Balaaiem fields and 2 ± 0.05 (?g/ml) for Ni, 4.8 ± 0.25 (?g/ml) for V and 2 ± 0.10 (?g/ml) for Fe at Wastern Desert fields
Determination of Nickel, Vanadium and Iron in Crude Oil by Three-Phase Plasma Arc Spectrometry
Ghatass, Zekry F.
2002-12-01
Three-phase plasma arc (TPPA) with ultrasonic nebulizer is developed for simultaneous determination of trace elements in crude oil samples. Ultrasonic nebulizer is used instead of pneumatic nebulizer in order to minimize the problems caused by the oil viscosity during the operation. This system was used for determination of some trace elements (V, Ni, and Fe) in a crude oil samples. Methyl isobutyl ketone (MIBK) was used to dilute the oil samples. The TPPA instrument offers several advantages including a low cost power supply with no radio frequency, linear dynamic ranges from 4 to 5 of orders of magnitude, and detection limits (0.121, 0.313 and 0.242 (?g/ml) for Ni, V and Fe respectively. The average concentrations were 31 ± 0.45 (?g/ml) for Ni, 40 ± 0.88 (?g/ml) for V and 8 ± 0.74 (?g/ml) for Fe at Balaaiem fields and 2 ± 0.05 (?g/ml) for Ni, 4.8 ± 0.25 (?g/ml) for V and 2 ± 0.10 (?g/ml) for Fe at Wastern Desert fields.
Mulchandani, Ketan; Kar, Jayaranjan R; Singhal, Rekha S
2015-07-01
Commercial exploitation of microalgae for biofuel and food ingredients is hindered due to laborious extraction protocols and use of hazardous chemicals. Production of lipids in the microalga grown in modified BG11 medium was evaluated to arrive at the appropriate harvesting conditions. The use of three phase partitioning (TPP) as a green approach for extraction of lipids from Chlorella saccharophila was investigated. Cells disrupted by probe sonication were used for separation of lipids by TPP. The TPP-optimized conditions of 30 % ammonium sulfate, using slurry/t-butanol of 1:0.75 for 60 min at 25 to 35 °C, showed a lipid recovery of 69.05?±?3.12 % (w/w) as against 100 % (w/w) by using chloroform-methanol extraction. Subsequently, parameters of high-pressure homogenization for cell disruption were optimized for maximum recovery of lipids by TPP. A final recovery of 89.91?±?3.69 % (w/w) lipids was obtained along with ?1.26 % w/w carotenoids of dry biomass in the t-butanol layer and protein content of ?12 % w/w of dry biomass in the middle protein layer due to ammonium sulfate precipitation, after performing TPP under the optimized conditions. Graphical Abstract ?. PMID:25969157
Impulse Three Phase Power Supply Used for a Gliding Plasma Discharge
Salazar-Torres, J. A.; Pacheco-Sotelo, J.; Valdivia-Barrientos, R.; Pacheco-Pacheco, M.; Ramos-Flores, F.; Soria-Arguello, G.; Ibańez-Olvera, M.
2015-03-01
Power sources used for generating plasma have different configurations depending on the particular application; the aim here comprises the maximum energy transfer to the plasma discharge reaching. This work shows the performance and versatility of a simple impulse phase power source, applied to gliding arc plasma discharge. It is capable of changing the operating frequency from 5 kHz up to 150 kHz and the duty cycle from 1% to 33% in all three phases, each one connected to three divergent tungsten electrodes. This allows a soft start plasma ignition until the full load is reached. This converter uses a sequential logic circuits composed by flip-flops, gates drivers, IGBT's and high voltage ferrite transformers. These features facilitate the maximum energy transfer to the plasma without using more complex electronic structures. The effect of frequency, duty cycle, voltage and current wave form signals is here described. This power supply has the adaptability to work whit different type of gas such as Argon, Helium, Air and Nitrogen. A Matlab Simulink simulation validates the experimental results. The main features and advantages of this configuration are also defined.
Influence of structured packing on gas holdup in a three-phase bubble column
DEFF Research Database (Denmark)
Monsalvo, Matias Alfonso; Böhm, Ursula
2007-01-01
In this work, the influence of structured packing on gas holdup in gas-liquid-solid dispersions has been studied. The experiments were carried out in an empty column and in column containing structured packing operating under identical conditions. Glass beads and silicon carbide particles were used as the solid material and the volumetric fraction of solids was varied from 0% to around 10%. The liquid viscosity was strongly modified using water, CMC solution and glycerol. The experimental results obtained with both columns were compared with previous results obtained in two-phase bubble columns. The influence of structured packing on the total gas holdup for different superficial gas velocities was found to be similar with and without suspended solids. Therefore, the results obtained in this work were analysed on the basis of correlations derived earlier for gas-liquid dispersions. Excepting the results obtained with glycerol, these correlations can predict the gas holdup of three-phase bubble columns with reasonable accuracy. (C) 2007 Elsevier Ltd. All rights reserved.
MICROGRID INVERTER OPERATION IN THREE PHASE GRID-CONNECTED AND DISCONNECTED MODES
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ASWATHY JEEVAN
2013-11-01
Full Text Available A Microgrid consists of interconnected distributed generators, loads and intermediate storage units. Microgrid inverter is used for the complex control of Microgrid. This paper introduces two modes of operation for Microgrid inverter. They are Grid Connected and Grid-Disconnected modes of operation. When a Microgrid is grid-connected, it behaves as a controllable load or source. During this mode of operation, the primary function of the Microgrid is to satisfy its entire load requirement. When in Grid- Connected operation, it uses current tracking by adjusting the output current to the grid to achieve energy transmission. The Microgrid should disconnect when an abnormal condition occurs in the grid. It uses voltage close loop control, by adjusting the output voltage to ensure stable load voltage when it is disconnected. Microgrid inverter switches smoothly between two modes, when grid fails or recovers. TheMicrogrid inverter used in this is a three phase inverter. This is mainly for high power applications. This increases feasibility, power and effectiveness of control strategy
Mat Rani, Ruzanita; Ismail, Wan Rosmanira
2013-04-01
Operator allocation is one of the most important decisions that can affect productivity in labor-intensive manufacturing system. Improper decision on operator allocation will reduce company's throughput and increase waste. Therefore, all factors such as operators' performance and operational constraints need to be considered in making the best operator allocation decision. Most of previous studies used two phases methodology. In two phases methodology, they used operational constraints and treated all operators to have the same level of performance for making decision on operator allocation. Therefore, in this paper a three-phase methodology is proposed to determine the optimal operator allocation. This methodology advances the existing approach on operator allocation by combining operators' performance and operational constraints. The methodology starts with evaluating the operators' performance. Then, it is followed with determining inputs and outputs for operator allocation alternatives and it ends with determining the optimal operator allocation. This paper will give ideas and directions to the management of the manufacturing company in determining the optimal operator allocation decision.
Sagu, Sorel Tchewonpi; Nso, Emmanuel Jong; Homann, Thomas; Kapseu, César; Rawel, Harshadrai M
2015-09-15
The stems of Abrus precatorius were used to extract a beta-amylase enriched fraction. A three phase partitioning method and a Doehlert design with 3 variables (ratio of crude extract/t-butanol, the ammonium sulphate saturation and pH) were used. The data was fitted in a second-order polynomial model and the parameters were optimized to enrich beta-amylase. Experimental responses for the modulation were recovery of activity and the purification factor. The optimal conditions were: a ratio of crude extract/t-butanol of 0.87 (v/v), saturation in ammonium sulphate of 49.46% (w/v) and a pH of 5.2. An activity recovery of 156.2% and a purification factor of 10.17 were found. The enriched enzyme was identified as a beta-amylase and its molecular weight was 60.1kDa. Km and Vmax values were 79.37mg/ml and 5.13U/ml, respectively and the highest activity was registered at a temperature of 70°C and a pH between 6 and 6.5. A significant stabilization of the beta-amylase was observed up to 65°C. PMID:25863622
Optimal Power Flow in three-phase islanded microgrids with inverter interfaced units
DEFF Research Database (Denmark)
Sanseverino, Eleonora Riva; Quang, Ninh Nguyen
2015-01-01
In this paper, the solution of the Optimal Power Flow (OPF) problem for three phase islanded microgrids is studied, the OPF being one of the core functions of the tertiary regulation level for an AC islanded microgrid with a hierarchical control architecture. The study also aims at evaluating the contextual adjustment of the droop parameters used for primary voltage and frequency regulation of inverter interfaced units. The work proposes a mathematical method for the OPF solution also considering the droop parameters as variables. The output of the OPF provides an iso-frequential operating point for all the generation units and a set of droop parameters for primary regulation. In this way, secondary regulation can be neglected in the considered hierarchical control structure. Finally, the application section provides the solution of the OPF problem over networks of different sizes and a stability analysis of the microgrid system using the optimized droop parameters, thus giving rise to the optimized management of the system with a new hierarchical control architecture.
ADVANCED DIAGNOSTIC TECHNIQUES FOR THREE-PHASE SLURRY BUBBLE COLUMN REACTORS(SBCR)
Energy Technology Data Exchange (ETDEWEB)
M.H. Al-Dahhan; L.S. Fan; M.P. Dudukovic
2002-07-25
This report summarizes the accomplishment made during the third year of this cooperative research effort between Washington University, Ohio State University and Air Products and Chemicals. Data processing of the performed Computer Automated Radioactive Particle Tracking (CARPT) experiments in 6 inch column using air-water-glass beads (150 {micro}m) system has been completed. Experimental investigation of time averaged three phases distribution in air-Therminol LT-glass beads (150 {micro}m) system in 6 inch column has been executed. Data processing and analysis of all the performed Computed Tomography (CT) experiments have been completed, using the newly proposed CT/Overall gas holdup methodology. The hydrodynamics of air-Norpar 15-glass beads (150 {micro}m) have been investigated in 2 inch slurry bubble column using Dynamic Gas Disengagement (DGD), Pressure Drop fluctuations, and Fiber Optic Probe. To improve the design and scale-up of bubble column reactors, a correlation for overall gas holdup has been proposed based on Artificial Neural Network and Dimensional Analysis.
Predictive Duty Cycle Control of Three-Phase Active-Front-End Rectifiers
DEFF Research Database (Denmark)
Song, Zhanfeng; Tian, Yanjun
2016-01-01
This paper proposed an on-line optimizing duty cycle control approach for three-phase active-front-end rectifiers, aiming to obtain the optimal control actions under different operating conditions. Similar to finite control set model predictive control strategy, a cost function previously constructed based on the desired control performance is adopted here, which is essential for the solving process of the optimizing problem. On the other hand, differently, with respect to the proposed strategy, duty cycle signals are optimized, instead of possible switching states. The determination of optimal duty cycles is made by predicting the effect of duty cycles on instantaneous current variations and minimizing the cost function. Due to the adoption of behavior prediction, the proposed controller inherits the excellent dynamic characteristics of predictive controllers. Moreover, the application of optimal duty cycles determined by cost function minimization automatically ensures optimum operations of converters within each sampling period. Improved transient and steady-state features of the proposed strategy are confirmed by experimental validations and in-depth comparisons with linear controllers, deadbeat predictive controllers, and finite control set model predictive control strategies.
Analytical Solution to the Riemann Problem of Three-Phase Flow in Porous Media
Energy Technology Data Exchange (ETDEWEB)
Juanes, Ruben; Patzek, Tadeusz W.
2002-09-26
In this paper we study one-dimensional three-phase flow through porous media of immiscible, incompressible fluids. The model uses the common multiphase flow extension of Darcy's equation, and does not include gravity and capillarity effects. Under these conditions, the mathematical problem reduces to a 2 x 2 system of conservation laws whose essential features are: (1) the system is strictly hyperbolic; (2) both characteristic fields are nongenuinely nonlinear, with single, connected inflection loci. These properties, which are natural extensions of the two-phase flow model, ensure that the solution is physically sensible. We present the complete analytical solution to the Riemann problem (constant initial and injected states) in detail, and describe the characteristic waves that may arise, concluding that only nine combinations of rarefactions, shocks and rarefaction-shocks are possible. We demonstrate that assuming the saturation paths of the solution are straightlines may result in inaccurate predictions for some realistic systems. Efficient algorithms for computing the exact solution are also given, making the analytical developments presented here readily applicable to interpretation of lab displacement experiments, and implementation of streamline simulators.
Modeling of a three-phase reactor for bitumen-derived gas oil hydrotreating
Energy Technology Data Exchange (ETDEWEB)
Chacon, R.; Canale, A.; Bouza, A. [Departamento de Termodinamica y Fenomenos de Transporte. Universidad Simon Bolivar, Caracas (Venezuela, Bolivarian Republic of); Sanchez, Y. [Departamento de Procesos y Sistemas. Universidad Simon Bolivar (Venezuela, Bolivarian Republic of)
2012-01-15
A three-phase reactor model for describing the hydrotreating reactions of bitumen-derived gas oil was developed. The model incorporates the mass-transfer resistance at the gas-liquid and liquid-solid interfaces and a kinetic rate expression based on a Langmuir-Hinshelwood-type model. We derived three correlations for determining the solubility of hydrogen (H{sub 2}), hydrogen sulfide (H{sub 2}S) and ammonia (NH{sub 3}) in hydrocarbon mixtures and the calculation of the catalyst effectiveness factor was included. Experimental data taken from the literature were used to determine the kinetic parameters (stoichiometric coefficients, reaction orders, reaction rate and adsorption constants for hydrodesulfuration (HDS) and hydrodenitrogenation (HDN)) and to validate the model under various operating conditions. Finally, we studied the effect of operating conditions such as pressure, temperature, LHSV, H{sub 2}/feed ratio and the inhibiting effect of H{sub 2}S on HDS and NH{sub 3} on HDN. (author)
Protection and Control of Three-Phase Induction Motor using Crouzet Millenium PLC
Directory of Open Access Journals (Sweden)
K.L.Priyanka
2014-12-01
Full Text Available Induction Motors (IM are used in many industrial applications in a wide range of operating areas as they have simple and robust structure, and low production costs. The knowledge about fault behavior of an Induction Motor drive is extremely important from standpoint of improved system design, protection, and fault tolerant control. Here different problems are dealt such as overvoltage, overcurrent, over speed which are being faced by IM’s during their course of operation. There are various methods for fault detection and protection of Induction Motors. Some of them are Online fault detection, Stator fault monitoring techniques, Microcontroller based protection system and Programmable Logic Controller (PLC based protection system. In this context, protection for three-phase Induction Motor is enabled using Crouzet Millenium PLC. The PLC correlates the operational parameters of the 3-Ř Induction Motor with the desired values preset by the user in the PLC that continuously monitor the system and isolate it during fault conditions. Thus, PLC proves an effective tool in industrial control of electric drives.
Directory of Open Access Journals (Sweden)
Wang Changzhou
2012-11-01
Full Text Available The traditional large electroslag remelting furnaces have many shortages, such as high short-network impedance and inductance, long maintenance time for electrode replacement, low stiffness of driveline, and low control accuracy of remelting speed. The present research was aimed to solve these problems through structure modification and constant remelting speed control for a 120-t electroslag remelting (ESR furnace. Based on the technique of three-phase double electrodes in series, the short-network system and the structure of the 120-t ESR furnace were improved; and a continuous feeding system for the self-consumption electrode was proposed. A self-designed fully hydraulic driveline system with three degrees of freedom was successfully applied to the 120-t ESR furnace. An electrode auto-replacement system and the S-style speed-control curve of electrode-feeding system were designed on the basis of the soft measurement/sensing model on the remaining electrode length so as to obtain a high accuracy control system for constant remelting speed. The experiment products showed good surface quality and cross-sectional results, indicating good system control, and verifying the effectiveness of the structure modification of the furnace.
Magnetic field structure of resonant, three phase conductor configurations in TEXTOR
International Nuclear Information System (INIS)
Plasma-wall interaction in large tokamaks poses serious problems the solution of which requires (1) control of the energy exhaust, (2) control of the particle exhaust, (3) screening of the plasma core against impurities, (4) shielding of the first wall against hot charge exchange neutrals and against high convective or conductive power loads. Owing to the difficulties of divertors by engineering reasons already, the concept of a cool plasma mantle realized by impurity line radiation or by magnetic field ergodization in the vicinity of the plasma edge was considered. Ergodization in a well defined plasma region acts like a limiter, the shadow region of which is determined by the magnetic field structure. This definition of the plasma aperture requires conductor configurations which are based on helical windings having the same pitch as the field lines at the resonant (q = 3) surface. The magnetic field structure generated by resonant conductor configurations was analyzed already by field line tracing. Here configurations with the poloidal and toroidal mode numbers, m=18 and n=6, respectively, are investigated mainly by Fourier-analysis. To achieve an almost uniform power deposition at the 'first' wall, the perturbation pattern should not be static like in previous and present experiments but rotating. Therefore the compensated conductor doublets needed for DC-operation are replaced by triplets allowing e.g. for three-phase AC-operation. (author) 6 refs., 4 figs
Lack of hypervascularity on three phase bone scan: Osteoid osteoma revisited
International Nuclear Information System (INIS)
Osteoid osteoma is a benign skeletal neoplasm of unknown aetiology that is composed of osteoid and woven bone. The tumor is usually smaller than 1.5 cm in diameter. Osteoid osteoma can occur in any bone, but in approximately two thirds of patients, the appendicular skeleton is involved. The skull and facial bones are involved exceptionally. Radionuclide Scans virtually always show increased uptake of isotope. The average time from the onset of symptoms to diagnosis is reported to be 28 months with spinal tumours. Radionuclide bone scanning reduces the time to diagnosis in 66% of patients. The sensitivity of radionuclide bone scans is extremely high as it can demonstrate the tumour before abnormal radiographic findings are apparent. Classically a three phase bone scan shows increased vascularity and increased uptake in an osteoid osteoma. But it is not always the case. We present here a pictorial assay of our experience in imaging osteoid osteoma in twenty six patients. It is evident that scintigraphic evidence of hypervascularity is not always present in osteoid osteomas. (author)
Energy Technology Data Exchange (ETDEWEB)
Xiao, Bailu [ORNL; Hang, Lijun [ORNL; Riley, Cameron [University of Tennessee, Knoxville (UTK); Tolbert, Leon M [ORNL; Ozpineci, Burak [ORNL
2013-01-01
A three-phase modular cascaded H-bridge multilevel inverter for a grid-connected photovoltaic (PV) system is presented in this paper. To maximize the solar energy extraction of each PV string, an individual maximum power point tracking (MPPT) control scheme is applied, which allows the independent control of each dc-link voltage. PV mismatches may introduce unbalanced power supplied to the three-phase system. To solve this issue, a control scheme with modulation compensation is proposed. The three-phase modular cascaded multilevel inverter prototype has been built. Each H-bridge is connected to a 185 W solar panel. Simulation and experimental results are presented to validate the proposed ideas.
Compensation Of Single-Phase and Three-Phase Voltage Sag and Swell Using Dynamic Voltage Restorer
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Haniyeh Marefatjou
2012-10-01
Full Text Available DVR is a equipment which was connected in series and adjusting the loading voltage by feeding the voltage in system. The first installation was in 1996. usually DVR installed between sensitive loads feeder and source in distribution system .The main duty, fast support load voltage (by fast detection algorithm during disturbance to avoid any disconnection. in this paper approaches to compensate for voltage sag and swell as a common disturbance in voltage transmission and distribution networks is presented. A dynamic voltage restorer based on the dq0 algorithm for three-phase and dynamic voltage restorer based on the average detection method for single-phase are discussed, also in this paper we compare the two methods used to compensate the single-phase and three-phase process. result of three-phase and single-phase voltage sag and swell simulation has been presented by MATLAB/SIMULINK.
Directory of Open Access Journals (Sweden)
Rathnakannan Kailasam
2008-01-01
Full Text Available This paper describes the modelling and the analysis of control logic for a Nano-Device- based PWM controller. A comprehensive simple SPICE schematic model for Single Electron transistor has been proposed. The operation of basic Single Electron Transistor logic gates and SET flip flops were successfully designed and their performances analyzed. The proposed design for realizing the logic gates and flip-flops is used in constructing the PWM controller utilized for switching the buck converter circuit. The output of the converter circuit is compared with reference voltage, and when the error voltage and the reference are matched the latch is reset so as to generate the PWM signal. Due to the simplicity and accuracy of the compact model, the simulation time and speed are much faster, which makes it potentially applicable in large-scale circuit simulation. This study confirms that the SET-based PWM controller is small in size, consumes ultra low power and operates at high speeds without compromising any performance. In addition these devices are capable of measuring charges of extremely high sensitivity.
100 kV/2A three-phase constant-current repetitive-rate charging equipment
Tan Yu Gang; Chen Li Dong; Guo Zhi Gang; Zou Xiao Bing; Luo Min; Cao Shao Yun; Chang An Bi
2002-01-01
A 100 kV/2A three-phase constant-current repetitive-rate charging equipment was designed and constructed. A three-phase L-C converter is adopted as constant-current power source. Six Insulated Gate Bipolar Transistors (IGBTs) are connected in parallel to control the stop of charge. A Programmable Logical Controller (PLC) is the central element of the control unit. The equipment is used in the repetitive-rate discharge features test of the switch. It works stably under the conditions of 2A charging current, 10 Hz operating voltage, 100 kV repetitive rate and 1 mu F capacitor
Introduction to modern traffic flow theory and control the long road to three-phase traffic theory
Kerner, Boris S
2009-01-01
This in-depth treatment explains the nature of traffic breakdown and the resulting congestion in vehicular traffic on the basis of three-phase traffic theory, in a manner consistent with real measured traffic data. The author also addresses freeway traffic control methods within the framework of the theory. He demonstrates and explains why the earlier theoretical basis of transportation engineering, research and teaching cannot adequately describe traffic breakdown as observed in measured traffic data. Links between three-phase traffic theory and earlier traffic flow theories are discussed. La
Use of Analytical Solutions to Optimize Simulation of Multicomponent Three-Phase Displacements
Laforce, Tara
2010-05-01
The conservation law for oil/water/gas flow in porous media can be highly sensitive to numerical dispersive effects, particularly in systems with substantial partitioning of components between the gas and oil phases. As a consequence, it is not typically possible to perform field-scale simulations with a sufficiently fine-grid to accurately model compositional displacements such as CO2 injection into oil fields for storage or enhanced oil recovery (EOR). The purpose of this study is to use analytical results to demonstrate the numerical errors in water and gas injection simulations in one dimension (1D) and to discuss the applicability of simplified models in obtaining an accurate simulated solution. Recently analytical solutions have become available for simultaneous water and gas (sWAG) flooding for three-phase multicomponent compositional systems (LaForce and Orr, 2009). This work showed the surprising result that excessive water injection can interfere with the development of multicontact miscibility (MCM) between the oil and gas phases. Multicontact miscibility occurs when a combination of thermodynamics and flow through porous media cause the formation of a single hydrocarbon phase. When MCM occurs hydrocarbons are displaced from the reservoir much more efficiently than in an immiscible gas or water flood. This presentation will compare and contrast the predicted displacements to a variety of models for sWAG flooding, including injection of water and a first-contact miscible (FCM) gas, three-phase compositional systems with developed miscibility and inert water (the aqueous phase contains only water, and water exists in only the aqueous phase) and compositional systems with developed miscibility in which all of the hydrocarbon components partition between all of the phases, but the water remains in the aqueous phase. Simulated solutions for each of the models are compared with the analytical solutions for various injection mixtures. This analysis can be used to determine when compositional simulation is necessary to achieve accurate results and when it is not worth the computational cost. The key results of this work are: 1) In compositional models where water is inert the analytical displacements using MCM and FCM models are nearly identical. In this case, 1D simulations using the MCM model are less accurate than the simulations of the simpler FCM system due to increased numerical dispersion in the compositional displacement. In this case the FCM model should be used for simulation in the reservoir. 2) In compositional models where there is a substantial partitioning of hydrocarbons into the aqueous phase the presence of excessive water can cause miscibility to fail to develop in compositional systems. For these displacements use of the FCM model will give an incorrect displacement and the fully compositional model must be used in simulations. However, when miscibility is developed, numerical effects again cause the 1D MCM simulation to be less accurate than the FCM solution. Reference: LaForce, T., and Orr, F.M, Jr. (2009) "Four-Component Gas/Water/Oil Displacements in One Dimension: Part III Development of Miscibility," Transport in Porous Media, 10.1007/s11242-008-9311-z
NUMERICAL ANALYSES FOR TREATING DIFFUSION IN SINGLE-, TWO-, AND THREE-PHASE BINARY ALLOY SYSTEMS
Tenney, D. R.
1994-01-01
This package consists of a series of three computer programs for treating one-dimensional transient diffusion problems in single and multiple phase binary alloy systems. An accurate understanding of the diffusion process is important in the development and production of binary alloys. Previous solutions of the diffusion equations were highly restricted in their scope and application. The finite-difference solutions developed for this package are applicable for planar, cylindrical, and spherical geometries with any diffusion-zone size and any continuous variation of the diffusion coefficient with concentration. Special techniques were included to account for differences in modal volumes, initiation and growth of an intermediate phase, disappearance of a phase, and the presence of an initial composition profile in the specimen. In each analysis, an effort was made to achieve good accuracy while minimizing computation time. The solutions to the diffusion equations for single-, two-, and threephase binary alloy systems are numerically calculated by the three programs NAD1, NAD2, and NAD3. NAD1 treats the diffusion between pure metals which belong to a single-phase system. Diffusion in this system is described by a one-dimensional Fick's second law and will result in a continuous composition variation. For computational purposes, Fick's second law is expressed as an explicit second-order finite difference equation. Finite difference calculations are made by choosing the grid spacing small enough to give convergent solutions of acceptable accuracy. NAD2 treats diffusion between pure metals which form a two-phase system. Diffusion in the twophase system is described by two partial differential equations (a Fick's second law for each phase) and an interface-flux-balance equation which describes the location of the interface. Actual interface motion is obtained by a mass conservation procedure. To account for changes in the thicknesses of the two phases as diffusion progresses, a variable grid technique developed by Murray and Landis is employed. These equations are expressed in finite difference form and solved numerically. Program NAD3 treats diffusion between pure metals which form a two-phase system with an intermediate third phase. Diffusion in the three-phase system is described by three partial differential expressions of Fick's second law and two interface-flux-balance equations. As with the two-phase case, a variable grid finite difference is used to numerically solve the diffusion equations. Computation time is minimized without sacrificing solution accuracy by treating the three-phase problem as a two-phase problem when the thickness of the intermediate phase is less than a preset value. Comparisons between these programs and other solutions have shown excellent agreement. The programs are written in FORTRAN IV for batch execution on the CDC 6600 with a central memory requirement of approximately 51K (octal) 60 bit words.
Characterization of a three-phase response in gloved cold-stressed fingers.
Shitzer, A; Endrusick, T L; Stroschein, L A; Wallace, R F; Gonzalez, R R
1998-07-01
Seven gloves were studied worn by eight sedentary subjects (six men and two women) exposed to cold-dry, C D, (mean dry bulb temperature Tdb = -17.2 degrees C; mean dew point temperature Tdp = -25.1 degrees C), and cold-wet, C-W, (Tdh = 0 degrees C; Tdp = -8.4 degrees C) conditions. Mean endurance times were 75 min for the C-D and 162 min for the C W conditions. A three-phase response pattern of the temperature in the fingers was characterized. Phase I comprised an initial period during which finger temperature remained close to the pre-exposed level, due to delayed vasoconstriction in the finger. Phase II involved an exponential-like decrease of finger temperature indicative of the onset of vasoconstriction in the finger. Phase III manifested periodic finger temperature changes due to cold induced vasodilatation (CIVD). Mean wave patterns for phase III indicated approximately 3.5 waves x h(-1) in the C D but only about 2 waves x h(-1) in the C-W condition. Extension of endurance time, due to CIVD, was defined as the difference in time between the actual end of the experiment and the time the finger-tip would have reached the set temperature endurance limit as extrapolated by a continued exponential drop. Three overall response patterns of fingers in the cold were characterized: type A exhibiting all 3 phases; type B1 or B2 exhibiting either phases I+ II or phases II+ III; and type C showing only phase II. Considerable inter- and intra-subject variability was found. In both test conditions the final physiological thermal states of the subjects were between comfortable and slightly uncomfortable but acceptable and thus did not correlate with the responses in the fingers. PMID:9694315
Numerical analysis of a three-phase system with a fluctuating water table
International Nuclear Information System (INIS)
Numerical simulations are presented of a one-dimensional, multiphase flow system that involves the redistribution of aqueous-phase liquids and nonaqueous-phase liquids (NAPLs) by a fluctuating water table. The numerical analyses were completed using an integrated-volume, finite-difference-based solution scheme of the governing multiphase conservation equations and constitutive theory. Conservation equations were solved for two components water and oil, with the assumption of a passive gas-phase. Nonlinearities introduced into the governing conservation equations through the constitutive theory were handled with a multivariable Newton-Raphson iterative scheme. The functional relationships between the phase relative permeability, the phase saturation, and phase pressures in porous media were described with a general theoretical model that includes the effects of air and oil occlusion during imbibition. Parameters required for the theoretical model were defined for two-phase systems (e.g., air- water, air-oil, and oil-water). The theoretical model assumes that wettability decreases in the following order: water, oil, air. Results from the numerical simulations are compared against measurements taken from a previous multiphase flow experiment. The experiment involved subjecting an initially water-drained, three-phase system (i.e., air-oil-water), to a fluctuating water table. The experimental objective was to quantify the entrapment of air and NAPL by phases of greater wettability under dynamic conditions. Comparison of numerical and experimental results were made for two ratios of imbibition to drainage characteristic, curve-shape parameters and two models for relative permeability in two-phase systems. A description of the numerical methods used to solve the governing conservation and constitutive equations for multiphase hysteretic conditions is given