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.
Zulkifilie Bin Ibrahim; Md. Liton Hossain; Ismadi Bin Bugis; Nik Munaji Nik Mahadi; Ahmad Shukri Abu Hasim
2014-01-01
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 m...
Three phase voltage source converter current analysis
International Nuclear Information System (INIS)
The proposed rectifier system consists of a three-phase diode bridge circuit as a main power circuit, A C reactors, and an additional circuit, which serves as an active filter with low switching frequencies and forced-commutation circuit for the diodes. These papers describe the operation principle, analysis of the waveforms of input voltage and current, the calculated of A C input current, multiple phase-shifted systems, and the experimental result. Avery conventional method was employed to analyze the input current equation; in that, the ripple output was neglected. The theory developed in this paper was verified twice; by calculation result and experiments. The calculated A C input the simple program using the algorithm of current equations calculated current waveforms presented in this paper. A switching circuit has been added to the diode rectifier, serving as an active filter and a forced-commutation circuit for diodes systems
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.
Directory of Open Access Journals (Sweden)
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.
A Comprehensive Study of Modulation Strategies for Three Phase Low Cost PWM Converter
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S. BHATTACHARYA
2011-07-01
Full Text Available A three phase voltage source converter using six power switches is a very important structure with wide variety of applications involving sophisticated ac drives, active power filters and power supplies etc. PWM voltage source inverters are also being incorporated in grid connected distributed power generating units to provide secure and reliable power to the utility grid. Due to the popularity of three-phase PWM converters there have been efforts in reducing the component count in these power electronic converters as a cost effective substitute. These researches led to the development of four-switch converter topology. The four switches present in thepower circuit can be controlled in various ways to deliver the desired characteristics of sinusoidal source current, ability to deliver unity or even leading power factor, bidirectional power flow. To obtain such characteristics of the converter, various control techniques have been envisaged and implemented. The other PWM strategies have their own advantages and disadvantages. In this paper a study of the various control methods applied to four-switch PWM converter is presented are presented along with their performancecomparison.
Control and Modeling of Shaft Generator with PWM Voltage Source Inverter for ship
Sathish Kumar T; Gowrishankar J
2012-01-01
This papers deals with well – based mathematicalmodeling of variable speed alternator (Shaft Generator) withPWM voltage source inverter used in ship. Detailed knowledge ofelectromagnetic characteristics of shaft generator is necessary fordesign complex ship's power system. Such knowledge isobtainable only by numerical simulations. The dynamic behaviorof shaft generators, SPWM voltage source inverter and theircontrollers during load variations are also discussed with the helpof MATLAB/SIMULI...
Control and Modeling of Shaft Generator with PWM Voltage Source Inverter for ship
Directory of Open Access Journals (Sweden)
Sathish Kumar T
2012-07-01
Full Text Available This papers deals with well – based mathematicalmodeling of variable speed alternator (Shaft Generator withPWM voltage source inverter used in ship. Detailed knowledge ofelectromagnetic characteristics of shaft generator is necessary fordesign complex ship's power system. Such knowledge isobtainable only by numerical simulations. The dynamic behaviorof shaft generators, SPWM voltage source inverter and theircontrollers during load variations are also discussed with the helpof MATLAB/SIMULINK. Elimination of harmonic contentsusing sinusoidal pulse width modulation also discussed here.
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
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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.
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.
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
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede
2012-01-01
The virtual output impedance loop is known as an effective way to enhance the load sharing stability and quality of droop-controlled parallel inverters. This paper proposes an improved design of virtual output impedance loop for parallel three-phase voltage source inverters. In the approach, a virtual output impedance loop based on the decomposition of inverter output current is developed, where the positive- and negative-sequence virtual impedances are synthesized separately. Thus, the negative-sequence circulating current among the parallel inverters can be minimized by using a large negative-sequence virtual resistance even in the case of feeding a balanced three-phase load. Furthermore, to adapt to the variety of unbalanced loads, a dynamically-tuned negative-sequence resistance loop is designed, such that a good compromise between the quality of inverter output voltage and the performance of load sharing can be obtained. Finally, laboratory test results of two parallel three-phase voltage source inverters are shown to confirm the validity of the proposed method.
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.
DEFF Research Database (Denmark)
Vasquez, Juan Carlos; Guerrero, Josep M.
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 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. Also, a synchronization algorithm is presented in order to connect the MicroGrid to the grid. Experimental results are provided to validate the performance and robustness of the parallel VSI system control architecture.
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Omonowo David Momoh
2014-07-01
Full Text Available The analysis of a carrier-based PWM two level voltage source inverter for a nine phase induction machine drive system is presented in this paper. Methods for generating zero-sequence signals during balanced and unbalanced condition are established. Simulation results for the analysis are presented. Two fault conditions involving the voltage source inverter and the nine-phase squirrel cage induction machine load are investigated. For the two fault scenarios considered, the effects on the performance characteristics of the induction machine load are highlighted. The simulation results obtained show that the two imbalance conditions considered result in substantial oscillations on the electromagnetic torque of the machine with attendant reduction in the torque rating. There is also large slip in the rotor speed.
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Sunil Kumar Chaudhary
2012-10-01
Full Text Available The authors present the design, simulation and analysis of a single phase voltage source inverter using soft switching techniques. The performance of the inverter has been compared in terms of harmonic contents present in output voltage and current. The research works for a PWM inverter along with a LLCC filter has been investigated. This paper also investigated the performance of the same inverter with a feedback controller with a closed loop feedback path to maintain rated output voltage. This work is helpful for the inverter used in application where high quality ac wave is prime requirement
Control Schemes for Auxiliary Switches of Three-Phase PWM Resonant Snubber Inverters
Hoshi, Nobukazu; Oguchi, Kuniomi
Control schemes for auxiliary switches of PWM controlled three-phase resonant snubber inverters (RSIs) are proposed. The control schemes proposed in this paper are based on a conventional PWM technique. To avoid zero voltage switching lost conditions, the conventional PWM technique is modified in the proposed schemes. The proposed control schemes are so simple that they are suitable for digital control. In this paper, a CPLD (Complex Programmable Logic Device)-based control IC, which realizes the proposed control schemes, for three-phase auxiliary RSIs is also proposed and implemented. The IC generates gate-signals for main- and auxiliary-devices of the three-phase RSI based on the proposed control schemes. The effectiveness of the proposed control schemes were verified through the experiments. As the results, ZVS (Zero Voltage Switching) turn-on at the main devices was achieved and a smooth sinusoidal output current was obtained by use of the control IC.
Comparative Analysis of PWM Techniques for Three Level Diode Clamped Voltage Source Inverter
Zulkifilie Bin Ibrahim; Md. Liton Hossain; Ismadi Bin Bugis; Jurifa Mat Lazi; Nurazlin Mohd Yaakop
2014-01-01
Multilevel inverters are increasingly being used in high-power medium voltage industrial drive applications due to their superior performance compared to conventional two-level inverters. Thre are a number of Pulse width modulation (PWM) techniques applied in recent years. The most widely applied PWM techniques are Sine Pulse Width Modulation (SPWM) and Space Vector Pulse Width Modulation (SVPWM). SPWM is the most simple modulation technique that can realize easily in analog circuit. Howe...
Comparative analysis of SPWM and SVPWM control for three phase inverter
Vinoth Kumar, K.; Prawin Angel Michael; John, Joseph P.; Suresh Kumar, S.
2010-01-01
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 ...
Selvamuthukumaran, Rajasekar; Natarajan, Muraly; Perianayagam, Ajay-d-vimalraj; Mahalingam, Sudhakaran
2010-01-01
This paper investigates the performanceand comparison of two pulse-width-modulation (PWM)techniques by employing direct current control strategyapplied to three phase shunt hybrid active power filter(SHAPF). The objective of SHAPF is to eliminate linecurrent harmonics and to incur reactive powercompensation. The direct current control strategy isimplemented using Standard PWM (S-PWM) and aModified PWM (M-WM), in order to compensatecurrent harmonic and reactive power generated bydifferent load...
A Novel Three-Phase UPS Inverter Driven by Error-Tracking-Mode PWM Scheme
Ohshima, Masaaki; Nakamura, Fuminori; Tamai, Shinzo; Yamamoto, Yuushin; Yoshida, Kouichi
With prevalence of information technology into our modern society and advance of automation technology in modern production process, the UPS market is assumed to make sustainable expansion. Error-Tracking-Mode PWM scheme offers novel constantly-sampled current-regulated switching algorithm to voltage-source power converters. This paper proposes a UPS in which Error-Tracking-Mode PWM scheme is applied to the current minor loop. The upper voltage control loop (ac-AVR) is developed afresh, that makes best of the PWM attributes. The equivalent output impedance of the UPS is derived theoretically for not only small signal but also large signal operation, that value can be arbitrarily specified by the ac-AVR parameters. A 3 kVA experimental setup was designed and fabricated, which has demonstrated the theoretical characteristics satisfactorily. The paper discusses the experimental results in detail. The authors believe that the paper presents a clue to realize independent and autonomic operation of dispersed PWM converters.
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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.
Roiu, Daniel; Tenconi, Alberto; Bojoi, Iustin Radu
2010-01-01
A new stationary frame control scheme for three-phase pulsewidth-modulation (PWM) rectifiers operating under unbalanced voltage dips conditions is proposed in this paper. The proposed control scheme regulates the instantaneous active power at the converter poles to minimize the harmonics of the input currents and the output voltage ripple. This paper's novelty is the development of a new current-reference generator implemented directly in stationary reference frame. This allows using proporti...
Comparative Analysis of PWM Techniques for Three Level Diode Clamped Voltage Source Inverter
Directory of Open Access Journals (Sweden)
Zulkifilie Bin Ibrahim
2014-07-01
Full Text Available Multilevel inverters are increasingly being used in high-power medium voltage industrial drive applications due to their superior performance compared to conventional two-level inverters. Thre are a number of Pulse width modulation (PWM techniques applied in recent years. The most widely applied PWM techniques are Sine Pulse Width Modulation (SPWM 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 effective DC utilization and lower switching frequency. Space vector pulse width modulation (SVPWM is widely used because of their easier digital realization and better DC bus utilization and lower THD. The complexity is due to the difficulty in determining the reference vector location, on times calculation, and switching states selection. This paper presents a simple SVPWM algorithm for diode clamped three level inverters based on standard two-level SVPWM which can easily determine the location of reference vector, calculate the on-times, the selection of switching states. Three level diode clamped inverter (3LDCI using space vector modulation technique has been modeled and simulated using MATLAB/SIMULINK and Origin 6.1 with a passive R-L load that can be extended to any level. Simulation results are presented to verify the proposed SVPWM control in terms of THD. The results are compared with conventional sinusoidal pulse width modulation (SPWM where SVPWM shows better performance than SPWM in terms of THD.
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.
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2014-12-01
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Cavagnino, Andrea; Boglietti, Aldo; Bojoi, Iustin Radu; Tenconi, Alberto
2008-01-01
A performance analysis of three-phase and dual three-phase (DTP) induction pulsewidth modulation (PWM) inverter-fed motor drives is conducted in this paper. The focus is on the efficiency performance of high-frequency DTP machines compared to their three-phase counterparts in low/medium power applications. For this purpose, a DTP machine, having two sets of stator three-phase windings spatially shifted by 30 electrical degrees (asymmetrical six-phase winding configuration), was tested for bot...
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.
Three phase six-switch PWM buck rectifier with power factor improvement
International Nuclear Information System (INIS)
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 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.
Three phase six-switch PWM buck rectifier with power factor improvement
Zafarullah Khan, M.; Mohsin Naveed, M.; Akbar Hussain, D. M.
2013-06-01
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 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.
Benslimane, Tarak; Abdelkrim, Thameur
2012-01-01
OPEN SWITCH FAULTS DETECTION AND LOCALIZATION ALGORITHM FOR THREE PHASE SHUNT ACTIVE POWER FILTER BASED ON TWO LEVEL VOLTAGE SOURCE INVERTER IN MAIN POWER SUPPLY CONSTANT AND VARIABLE FREQUENCY CONDITIONS
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P.Manikandan
2014-02-01
Full Text Available It has been found that by using Pulse with modulation technique can greatly reduce the harmonics distortions generated by the PV inverter. Harmonics reduction is the main consideration in three phase squirrel cage induction motor. We can improve the performance of the three phase squirrel cage Induction motor by the reduction of THD. In this research work, the harmonic distortion of the three phase induction motor was measured in terms of THD by Simulation model and the results of the Multiple Pulse With Modulation and Sinusoidal Pulse With Modulation inputs were compared to discover the lowest THD value. By using the PWM technique on the Three Phase Induction motor there was reduction in the VTHD by 6.98% and CTHD by 3.12% which in turn reduces the iron, winding and stray losses occurred in three phase squirrel cage induction motor.
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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.
Energy Technology Data Exchange (ETDEWEB)
Dahidah, Mohamed S.A. [School of Electrical and Electronic Engineering, The University of Nottingham, Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor (Malaysia); Agelidis, Vassilios G. [School of Electrical and Information Engineering, The University of Sydney, NSW (Australia)
2008-11-15
The paper presents a new variation of selective harmonic elimination pulse-width modulation (SHE-PWM) technique suitable for a high-power five-level converter used in constant frequency utility applications. The governing system of equations associated with the elimination of specific harmonics is defined based on an equal number of switching transitions when compared against the single-carrier sinusoidal PWM (SC-SPWM) technique. For this paper, it is assumed that the modulating signal (triangular carrier) of the equivalent SC-SPWM method has twenty per unit frequency. The switching transitions for every quarter period are therefore distributed between the converter levels according to the modulation index of SC-SPWM. It is confirmed that the proposed technique offers significantly higher converter bandwidth and higher dc bus utilization for the same switching transitions. Furthermore, the proposed SHE-PWM offers better harmonic performance compared to its SC-SPWM counterpart. Selected solutions for the switching transitions are presented and verified experimentally in order to confirm the effectiveness of the proposed technique. (author)
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.
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
International Nuclear Information System (INIS)
The integrated voltage compensation type active superconducting fault current limiter (SFCL) is composed of three air-core superconducting transformers and a three-phase four-wire PWM converter. In order to realize the current-limiting characteristics of the integrated active SFCL, it is needed to control the three-phase four-wire PWM converter flexibly and reasonably. Thereby, the control strategy for the converter is analyzed in this paper. In dq0 reference frame, the mathematical model of the converter is founded. The double-loop control strategy, consisting of voltage outer loop and current inner loop, is presented. Moreover, the voltage balance control for the split DC link capacitors is also considered. Using MATLAB, the simulation model of the integrated active SFCL is built. According to the simulation results, it is known that, the presented control strategy is feasible and valid, and the converter can work well under unsymmetrical and symmetrical fault conditions, and then the fault current can be limited quickly and effectively.
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
Energy Technology Data Exchange (ETDEWEB)
Leon, Andres E.; Solsona, Jorge A.; Busada, Claudio; Chiacchiarini, Hector [Instituto de Investigaciones en Ingenieria Electrica (IIIE) UNS-CONICET, Universidad Nacional del Sur, Av. Alem 1253, Bahia Blanca 8000 (Argentina); Valla, Maria Ines [Laboratorio de Electronica Industrial, Control e Instrumentacion (LEICI) and CONICET, Facultad de Ingenieria, Universidad Nacional de La Plata, La Plata 1900 (Argentina)
2009-08-15
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. (author)
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 potência os inversores de frequência atuam de forma importante em toda indústria. O inversor de frequência convencional contém elementos armazenadores de energia no seu elo de corrente contínua. Estes elementos armazenadores de energia sã [...] o capacitores eletrolíticos e possibilitam manter a tensão do elo de corrente contínua constante. Entretanto, quanto maior sua capacitância maior é a distorção da corrente de entrada. Com a substituição do banco de capacitores eletrolíticos por um capacitor de filme, diminui-se a distorção nas correntes de entrada, porém distorções indesejadas aparecem na tensão do elo de corrente contínua e também nas correntes de saída. Estas distorções são compostas por componentes harmônicas de baixas frequências. O conversor em matriz trifásico-trifásico por sua vez, possibilita a transferência direta de energia da entrada (rede) diretamente para a saída (carga) sem a necessidade de elementos armazenadores de energia como acontece no inversor de frequência. Entretando o desbalanceamento das tensões da entrada afetam diretamente a forma de onda das tensões da saída. Dessa maneira, este trabalho propõe um método de controle de corrente do conversor em matriz e do inversor de frequência sem banco de capacitores do elo de corrente contínua com objetivo de compensar o desbalanceamento das tensões de saída do conversor em matriz e compensar também as componentes harmônicas de baixa frequência que aparecem nas correntes de saída do inversor de frequência. O método proposto utiliza um controlador do tipo PI e modulação por vetores espaciais para que a frequência 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.
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.
Hensgens, Nico H.; Silva Ferna?ndez, Marcelo Alexis; Oliver Rami?rez, Jesu?s Angel; Alou Cervera, Pedro; Garci?a Sua?rez, Oscar; Cobos Ma?rquez, Jose? Antonio
2012-01-01
Different possible input filter configurations for a modular three-phase PWM rectifier system consisting of three interleaved converter cells are studied. The system is designed for an aircraft application where MIL-STD-461E conducted EMI standards have to be met and system weight is a critical design issue. The importance of a LISN model on the simulated noise levels and the effect of interleaving and power unbalance between the different converter modules is discussed. The effect of the num...
Three-phase Resonant DC-link Converter
Munk-Nielsen, Stig
2005-01-01
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...
Dual-Three Phase Induction Machine Drives Control—A Survey
Bojoi, Radu; Farina, Francesco; Profumo, Francesco; Tenconi, Alberto
The paper aims to perform an overview on the state-of-the-art in the control of multi-phase drives employing dual-three phase induction machines. In particular, the paper is focused on modeling aspects, Pulse-Width Modulation (PWM) techniques for Voltage Source Inverters (VSI), Field Oriented Control (FOC) and Direct Torque Control (DTC) strategies for dual-three phase induction machines. Furthermore, the paper briefly presents the advantages of dual-three phase induction motor drives over the conventional three-phase drives and the different applications reported in the literature.
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.
Manikandan, P.; V.Neviya; LIEUTENANT.J. GANESAN
2014-01-01
It has been found that by using Pulse with modulation technique can greatly reduce the harmonics distortions generated by the PV inverter. Harmonics reduction is the main consideration in three phase squirrel cage induction motor. We can improve the performance of the three phase squirrel cage Induction motor by the reduction of THD. In this research work, the harmonic distortion of the three phase induction motor was measured in terms of THD by Simulation model and the results of the Multipl...
Silva Ferna?ndez, Marcelo Alexis; Hensgens, Nico H.; Oliver Rami?rez, Jesu?s Angel; Alou Cervera, Pedro; Garci?a Sua?rez, Oscar; Cobos Ma?rquez, Jose? Antonio
2011-01-01
An EMI filter for a three-phase buck-type medium power pulse-width modulation rectifier is designed. This filter considers differential mode noise and complies with MIL-STD-461E for the frequency range of 10kHz to 10MHz. In industrial applications, the frequency range of the standard starts at 150kHz and the designer typically uses a switching frequency of 28kHz because the fifth harmonic is out of the range. This approach is not valid for aircraft applications. In order to design the switchi...
Feedforward Synchronised PWM for Adjustable Speed AC Drives with Different Control Modes
DEFF Research Database (Denmark)
Oleschuk, Valentin; Blaabjerg, Frede
2002-01-01
This paper presents a novel method of direct synchronised pulswidth modulation (PWM) for three-phase voltage source inverters, feeding induction motors with different control regimes. It is based on the universal algorithm with either simplified algebraic or accurate trigonometric control functions, with vector approached for determination of the pulse patterns, with vector approach for determination of the pulse patterns. Different control modes of the drive system with synchronised PWM, including standard scalar V/F control, and also V2/F = constant and V/F2 = constant control regimes, have been analysed in the paper. Simulations give the behaviour of the PWM techniques proposed. Both continuous and discontinuous schemes of synchronised PWM, applied for the corresponding control regime, have been analysed and compared.
Space Vector PWM Implementation for Z-Source Inverter
Directory of Open Access Journals (Sweden)
K Veera Reddy
2014-06-01
Full Text Available Space Vector Modulation (SVM Technique has become the most popular and important PWM technique for three phase Voltage Source Inverters. 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. This paper presents implementation of Space Vector Modulation technique for Two Level Z Source Inverter using MATLAB.
Morimoto, Keiki; Doi, Toshimitsu; Manabe, Haruhiko; Ahmed, Tarek; Hiraki, Eiji; Lee, Hyun-Woo; Nakaoka, Mutsuo
This paper presents a new circuit topology of full-bridge soft-switching PWM inverter linked DC-DC power converter composed of conventional full-bridge high frequency PWM inverter with high frequency transformer and an active quasi-resonant snubber consisting of an additional power switching device in series with DC busline and a lossless capacitor in parallel with DC busline. Under this proposed high frequency soft-switching PWM inverter linked DC-DC converter, four power switches in the full-bridge arms and DC busline series switch can achieve ZVS at turn-off commutation. By developing the advanced soft-switching PWM high frequency inverter type DC-DC converter, although the conduction power loss of DC busline series power switch increases a little, the total turn-off switching loss of full-bridge high frequency inverter power modules can be sufficiently lowered more and more in the higher frequency range of 60kHz. As a result, when the switching frequency of high frequency inverter power stage using IGBT power modules is designed so as to be more than about 10kHz, the more the switching frequency of inverter increases, the more this high frequency soft-switching DC-DC converter has remarkable advantage as for the power conversion efficiency as compared with the conventional hard-switching PWM inverter DC-DC converter. Its practical effectiveness of high power density and high performance is actually proved for TIG arc welding equipment in industry.
Speed Control and THD for Three Phase Induction Motor Using Simulink
Directory of Open Access Journals (Sweden)
Priya Janak 1
2014-06-01
Full Text Available Sinusoidal Pulse Width Modulation variable speed drives are increasingly applied in many new industrial applications that require superior performance. Be it domestic application or industry, motion control is required everywhere. Recently, developments in power electronics and semiconductor technology have lead improvements in power electronic systems. Recent developments in speed control methods of the induction motor have led to their large scale use in almost all electrical drives. Variable voltage and frequency supply to ac drives is invariably obtained from a three-phase voltage source inverter, which is carrier-based sinusoidal PWM. Simulink is utilized with MATLAB to get a reliable and flexible simulation. PWM technique is proven to be an effective way of controlling speed of induction motor. In ac motor drives, SPWM inverters make it possible to control both frequency and magnitude of the voltage and current applied to a motor. As a result, PWM inverter-powered motor drives are more variable and offer in a wide range better efficiency and higher performance when compared to fixed frequency motor drives. Three phase voltage-fed PWM inverters are recently showing growing popularity for multi-megawatt industrial drive applications. Simulation results are obtained using MATLAB/Simulink environment for effectiveness of the study.
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.
Current Controlled Voltage Source (CCVS)
Svoboda, James A.
This interactive website from professor James A. Svoboda of Clarkson University describes a circuit that contains a Current Controlled Voltage Source (CCVS). The gain of the CCVS can be changed using the scrollbar.
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 determinação experimental das capacitancias parasitas do motor de indução trifásico de rotor em gaiola. As capacitancias parasitas fazem parte do circuito equivalente do motor para estudos de interferência eletromagnética causada no mo [...] tor de indução em modo comum quando ele for acionado por inversor controlado por modulação por largura de pulsos (MLP). Os procedimentos propostos para o desenvolvimento deste novo método consistem em: a) determinação dos parâmetros do circuito equivalente do motor de indução trifásico, em regime permanente, através de ensaio em laboratório; b) estabelecer configurações de ligações entre o inversor MLP e o motor para medições das grandezas de interesse que são as seguintes: tensões de modo comum e de eixo, correntes de fuga e de eixo, através de circuito de medição 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 expressão matemática da definição de capacitancia; d) utilizar o software Pspice para simular o sistema motor de indução trifásico, alimentado por inversor MLP, com os circuitos equivalentes em baixas e altas frequências; 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.
Paul, R. N.; Arya, L. D.; Verma, H. K.
2012-09-01
In three-phase squirrel-cage ac traction motor, temperature-rise calculation during variable-voltage and variable-frequency starting is of vital importance and has to be predicted and critically examined. Under voltage source inverter supply with PWM, the generation of harmonics by inverter supply reduces the output during starting due to higher harmonic losses, thereby reducing the starting tractive effort in kN on locomotive wheel. Stator and rotor temperature-rises during starting have been determined for average acceleration torque in segmental zone (calculated from variable acceleration) which have been presented in the paper with both copper and aluminium alloy rotor bars.
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
Voltage Controlled Voltage Source (VCVS)
Dorf, Richard C.
Hosted by Clarkson University, this applet demonstrates a circuit that contains a voltage controlled voltage source (VCVS). The gain may be modified using the scroll bar. Even though brief, this resource can be used in a variety of different technical education classrooms.
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.
Synchronized Scheme of Continuous Space-Vector PWM with the Real-Time Control Algorithms
DEFF Research Database (Denmark)
Oleschuk, V.; Blaabjerg, Frede
2004-01-01
This paper describes in details the basic peculiarities of a new method of feedforward synchronous pulsewidth modulation (PWM) of three-phase voltage source inverters for adjustable speed ac drives. It is applied to a continuous scheme of voltage space vector modulation. The method is based on a representation of the pulse patterns as a function of the fundamental and switching frequencies of the drive system. Accurate trigonometric algorithms of vector PWM have been analysed, and also compared with the algebraic ones based on linear approximation of the durations of active switching states from their position inside clock-intervals. In order to provide smooth shock-less pulse-ratio changing and quarter-wave symmetry of the voltage waveforms, special synchronising signals are formed on the boundaries of the 60 clock-intervals. The process of gradual transition from continuous to discontinuous synchronous PWM at higher values of the fundamental frequency has also been described. Results of analysis of the spectral characteristics of the output voltage of the inverter show advantage of synchronous PWM in comparison with conventional asynchronous modulation at low indices of the frequency ratio between the switching and the fundamental frequency. Special attention has been given to the analysis and comparison of the computational effectiveness of the proposed algorithms of synchronized modulation. 0
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.
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.
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...
Inverted sine carrier for fundamental fortification in PWM inverters and FPGA based implementations
Jeevananthan S.; Nandhakumar R.; Dananjayan P.
2007-01-01
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...
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
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
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...
Voltage Source Converters with Energy Storage Capability
Xie, Hailian
2006-01-01
This project deals with voltage source converters with energy storage capability. The main objective is to study the possible benefits of energy storage to a power system with a VSC as the interface between them. First of all, a converter control system is proposed for a two level VSC. In the conventional converter control, the control system usually takes the voltage measured at the point where the converter is connected and calculates the reference voltage for the converter; with a modulati...
Modeling & Simulation of Fuel cell (Choi Model based 3-Phase Voltage Source Inverter
Directory of Open Access Journals (Sweden)
Gaurav Sachdeva
2011-10-01
Full Text Available 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 IM load. Simulations have been performed using PSIM 7.0.5 and MATLAB 7.0.4.
Nakamura, Mantaro; Yamazaki, Takayuki; Fujii, Yuma; Ahmed, Tarek; Nakaoka, Mutsuo
This paper proposes a new circuit topology of the three-phase soft switching PWM inverter and PFC converter using IGBT power modules, which has the improved active auxiliary switch and edge resonant bridge leg-commutation-link soft-switching snubber circuit with pulse current regenerative feedback loop as compared with the typical auxiliary resonant pole snubber discussed previously. This three-phase soft switching PWM double converter is more suitable and acceptable for a large capacity uninterruptible power supply, PFC converter, utility-interactive bi-directional converter and so forth. In this paper, the soft switching operation and optimum circuit design of the novel type active auxiliary edge resonant bridge leg commutation link snubber treated here are described for high power applications. Both the main active power switches and the auxiliary active power switches achieve soft switching under the principles of ZVS or ZCS in this three-phase inverter switching. This three-phase soft switching commutation scheme can effectively minimize the switching surge related electromagnetic noise and the switching power losses of the power semiconductor devices; IGBTs and modules used here. This three-phase inverter and rectifier coupled double converter system does not need any sensing circuit and its peripheral logic control circuits to detect the voltage or the current and does not require any unwanted chemical electrolytic capacitor to make the neutral point of the DC power supply voltage source. The performances of this power conditioner are proved on the basis of the experimental and simulation results. Because the power semiconductor switches (IGBT module packages) have the relation of the trade-off in the switching fall time and tail current interval characteristics as well as the conductive saturation voltage characteristics, this three-phase soft-switching PWM double converter can perform to improve actual efficiency in the output power ranges with a trench gate controlled MOS power semiconductor devices which is much more improved to the low saturation voltage. The effectiveness of this is verified from a practical point of view.
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.
Synchronised PWM Schemes for Three-level Inverters with Zero Common-mode Voltage
DEFF Research Database (Denmark)
Oleschuk, Valentin; Blaabjerg, Frede
2002-01-01
This paper presents results of analysis and comparison of novel synchronised schemes of pulsewidth modulation (PWM), applied to three-level voltage source inverters with control algorithms providing elimination of the common-mode voltage. The proposed approach is based on a new strategy of digital PWM with synchronous smooth pulses-ratio changing and a quarter-wave symmetry of the voltage waveforms. Three basic versions of both algebraic and trigonometric synchronised PWM have been analysed. Simulations give the behaviour of the proposed methods and show some advantage of synchronised PWM in comparison with asynchronous at low ratios between the switching and fundamentsl frequencies.
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.
Autonomous Three-Phase Induction Generator Supplying Unbalanced Loads
ION, C. P.; Marinescu, C.
2013-01-01
This paper presents a control method for a stand-alone micro hydro with induction generator (IG) supplying unbalanced three-phase loads. Besides voltage and frequency regulation, the phase balancing is ensured for this particular operating regime. The proposed control topology relies on a combination between a voltage source inverter (VSI) and a dump load (DL). The VSI imposes the system frequency and performs the unbalances compensation, while the DL deals with the voltage regulation. Ex...
Cascaded Nine Level Inverter Using Pulse Width Modulation And Hybrid PWM
Directory of Open Access Journals (Sweden)
Rohini Sharma
2014-05-01
Full Text Available The multilevel voltage source converters typically synthesize the staircase voltage wave from several levels of dc voltage sources. This paper presents a PWM modulation and hybrid modulation using cascaded topology which allows one to achieve high-quality output voltages and input currents and also outstanding availability due to their intrinsic component redundancy. The simulation results reveal that method can effectively eliminate harmonics in the output waveform of the inverter, and also low THD (Total Harmonics Distortion.
Directory of Open Access Journals (Sweden)
Naik R. L
2014-07-01
Full Text Available This paper presents harmonic and power quality analysis of two level and three level Diode Clamped Voltage Source Inverter (DCVSI. Purpose of analysis is to investigate performance of VSI in WECS in terms of power quality fed to grid, filter requirement and DC bus utilization. Modulation strategy used is Space Vector PWM (SVPWM for two levels and three levels DCVSI as it is readily available for digital implementation. Performance evaluation of VSI is measured through Weighted Total Harmonic Distortion (WTHD, IEC 1000-3-4 Regulation and Filtering Ratio (FR. Voltage Source Inverter and LCL filter are modeled in terms of switching function and state space technique respectively. These models integrated and simulated using MATLAB-SIMULINK. It is observed from simulation that DCVSI has better WTHD and higher DC Bus Utilization. Further it is also observed that DCVSI experiences lower switching loss and less filtering requirement.
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.
Dynamic Performance of a Back-to-Back HVDC Station Based on Voltage Source Converters
Khatir, Mohamed; Zidi, Sid-Ahmed; Hadjeri, Samir; Fellah, Mohammed-Karim
2010-01-01
The recent developments in semiconductors and control equipment have made the voltage source converter based high voltage direct current (VSC-HVDC) feasible. This new DC transmission is known as "HVDC Light or "HVDC Plus by leading vendors. Due to the use of VSC technology and pulse width modulation (PWM) the VSC-HVDC has a number of potential advantages as compared with classic HVDC. In this paper, the scenario of back-to-back VSC-HVDC link connecting two adjacent asynchronous AC networks is studied. Control strategy is implemented and its dynamic performances during disturbances are investigated in MATLAB/Simulink program. The simulation results have shown good performance of the proposed system under balanced and unbalanced fault conditions.
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.
Pinto, J. G.; Exposto, Bruno; Monteiro, V. Tor; Monteiro, Lu S. F. C.; Couto, Carlos; Afonso, Jo O. L.
2012-01-01
This paper presents the comparison between two three-phase Shunt Active Power Filters (SAPFs), one with Current-Source Inverter (CSI) and the other with Voltage-Source Inverter (VSI), which are used to compensate current harmonics and to control reactive power. The control algorithm of both SAPFs is based on the Instantaneous Reactive Power Theory (p-q Theory). The comparison here presented focuses on the Total Harmonic Distortion (THD) and RMS ...
Optimum space vector PWM algorithm for three-level inverter
Urmila, B.; Subba Rayudu, D.
2011-01-01
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 ...
La Hidalga-w, F. J.; Malik, O.
2013-01-01
This work shows that the direct PWM output electric signal, with a duty cycle controlled by light intensity, can beobtained using a circuit containing a saw-tooth voltage generator connected in series with a dc voltage source and ametal (semitransparent gate) oxide semiconductor capacitor (MOS-C).The internal PWM signal conversion occurs by the use of non-equilibrium physical processes in the semiconductorsubstrate of the MOS-C. The 10-20 V amplitude limited square PWM output signal is obtain...
Performance analysis of samarium cobalt P.M. synchronous motor fed from PWM inverters
International Nuclear Information System (INIS)
This paper presents an analysis and performance of samarium cobalt permanent magnet (P.M.) synchronous motors fed from two types of voltage source pulse width modulated (PWM) inverters. The analysis and test results on the steady state performance of a P.M. motor fed from PWM inverters are presented. PWM inverters are used in variable voltage variable frequency applications to avoid a double conversion process of ordinary inverters. In drives, they are used for voltage and speed regulation of motors. Use of modulation technique in inverters also allow to eliminate or minimize selected harmonics from the inverter output voltage
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.
Optimal condition of memristance enhancement circuit using external voltage source
Directory of Open Access Journals (Sweden)
Hiroya Tanaka
2014-05-01
Full Text Available Memristor provides nonlinear response in the current-voltage characteristic and the memristance is modulated using an external voltage source. We point out by solving nonlinear equations that an optimal condition of the external voltage source exists for maximizing the memristance in such modulation scheme. We introduce a linear function to describe the nonlinear time response and derive an important design guideline; a constant ratio of the frequency to the amplitude of the external voltage source maximizes the memristance. The analysis completely accounts for the memristance behavior.
The Application of FPGA in PWM Controlled Resonant Converter for an Ozone Generator
Mochammad Facta; Tole Sutikno; Zainal Salam
2013-01-01
Pulse Width Modulation (PWM) is a very common technique used in many different applications. The Conventional method its generation is the heart of the inverter system. This paper present methodology to generate Sinusoidal PWM (SPWM) signal for three-phase inverter based on EP20K200EFC484-2x Altera Field Programmable Gate Array (FPGA). Designing a PWM inverter drive using FPGA has several advantages, such as: it's quick, very modifiable, and very suitable for prototyping. In this paper...
Directory of Open Access Journals (Sweden)
V.Arun#1 , B.Shanthi
2013-06-01
Full Text Available 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 phase seven level Z-source diode clamped inverter have been analyzed. A simulation model of three phase seven level Z-source diode clamped inverter developed using MATLAB/SIMULINK and its performance has been analyzed.
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 señal 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.
Autonomous Three-Phase Induction Generator Supplying Unbalanced Loads
Directory of Open Access Journals (Sweden)
ION, C. P.
2013-05-01
Full Text Available This paper presents a control method for a stand-alone micro hydro with induction generator (IG supplying unbalanced three-phase loads. Besides voltage and frequency regulation, the phase balancing is ensured for this particular operating regime. The proposed control topology relies on a combination between a voltage source inverter (VSI and a dump load (DL. The VSI imposes the system frequency and performs the unbalances compensation, while the DL deals with the voltage regulation. Experiments have yielded the reliability of this configuration during generator loading and unbalanced loads supply.
Power Loss Calculation and Thermal Modelling for a Three Phase Inverter Drive System
Zhou, Z; M. S. Khanniche; P. Igic; S. M. Towers; Mawby, P.A.
2005-01-01
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 accur...
V Arun, 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 potência série e paralelo. Um controlador baseado no sistema de eixo de referência síncrona (SRF é usado na compensação de potência reativa e harmônica geradas por quaisquer configurações de cargas não lineares. Sob condições normais da rede elétrica o SEI trabalha na compensação das correntes de entrada e das tensões de saída. Dois conversores controlados em tensão e modulados por largura de pulso (PWM, chamados de filtros ativos série e paralelo, são usados para realizar o condicionamento ativo de potência série e paralelo. O filtro ativo série trabalha como uma fonte de corrente senoidal em fase com a tensão de entrada, drenando da rede correntes senoidais, balanceadas com baixas taxas de distorção harmônica (TDH. O filtro ativo paralelo trabalha como uma fonte de tensão senoidal em fase com a tensão de entrada, fornecendo para a carga tensões reguladas, senoidais e com baixas taxas de distorção harmônica. O desempenho do SEI é avaliado para sistemas trifásicos com quatro fios. Resultados experimentais são apresentados para confirmar os estudos teóricos.
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.
Valantina Stephen; Padma Suresh, L.; 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...
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
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.
Soft Commutated Three-Phase Dc-Dc Converter
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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.
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.
Power Quality Improvement using Dual Voltage Source Converter Based DVR
Suresh, A.; Govindaraj, V.
2014-01-01
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 critic...
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
Stabilized voltage sources for a slow neutron diffraction analyzer
International Nuclear Information System (INIS)
An unified voltage source (UVS) and filament voltage source (FVS) are described' The sources are used for a slow neutron diffraction analyzer. FVS supplies the filament of a gun cathode and provides beam currents upto 2 mA at electric currents upto 5A and voltages upto 8V. FVS is built by a compensation scheme with continuous control. It possesses a control element with high output power and trigger protection. The range of the EVS protection circuit operation threshold control is 1-5 A, instability of output voltage doesn't exceed 1 mV, the load power consumption doesn't exceed 40 W. UVS is also built according to compensation principle with continuous control and non-regulated power supply of a negative feedback amplifier. The output voltage is controlled within the limits of 5-250 V, maximum load current is 5 mA, instability of output voltage doesn't exceed 50 mV, maximum power consumption is 1.5 W. Simplicity of the UVS circuit is reached by application of the minimum number of active and passive elements, and reliability - by the circuit protection from overloads. Operation of the slow neutron diffraction analyzer, a control unit of which is built on the base of the above voltage sources, proves their reliability and convenience. Diffraction patterns of good quality are obtained
New Space Vector Selection Scheme for VSI Supplied Dual Three-Phase Induction Machine
Milicevic, D.; Katic, V.; Corba, Z.; Greconici, M.
2013-01-01
This paper presents a novel space vector selection scheme applicable for the control of dual three-phase induction motor drives supplied from a six-phase voltage source inverter (VSI). The vector selection method is based on the vector space decomposition technique (VSD). Unique vector selection pattern simplifies problems related to complicated implementation of standard VSD in commercially available digital signals processors (DSP). The proposed vector selection scheme is verified throu...
New Space Vector Selection Scheme for VSI Supplied Dual Three-Phase Induction Machine
Directory of Open Access Journals (Sweden)
MILICEVIC, D.
2013-02-01
Full Text Available This paper presents a novel space vector selection scheme applicable for the control of dual three-phase induction motor drives supplied from a six-phase voltage source inverter (VSI. The vector selection method is based on the vector space decomposition technique (VSD. Unique vector selection pattern simplifies problems related to complicated implementation of standard VSD in commercially available digital signals processors (DSP. The proposed vector selection scheme is verified through a theoretical analysis, computer simulations and practical experimental results conducted on a dual three-phase test rig prototype with control algorithm implemented in Texas Instrument?s TMS320F2808 DSP.
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.
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.
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.
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)
Performance Evaluation of Three Phase Bridge Module Type Diode Clamped Multilevel Inverter
C R Balamurugan, S. P. Natarajan
2012-01-01
This work proposes three phase five level Bridge module type Diode Clamped Multilevel Inverter (DCMLI) using various modulating techniques for induction motor load. These Pulse Width Modulating (PWM) techniques include Carrier Overlapping (CO) strategy, Variable Frequency (VF) strategy, Phase Shift (PS) strategy and Sub-Harmonic Pulse Width Modulation (SHPWM) i.e. Phase Disposition (PD) strategy, Phase Opposition Disposition (POD) strategy and Alternate Phase Opposition Disposition (APOD) str...
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...
Comparative analysis of third harmonic injection PWM and SPWM control techniques for UPS inverter
Energy Technology Data Exchange (ETDEWEB)
Wanjekeche, T.; Nicolae, D.V.; Jimoh, A.A. [Tshwane Univ. of Technology, Pretoria (South Africa). Dept. of Electrical Engineering
2008-07-01
Pulse width modulation (PWM) techniques for uninterruptible power supply (UPS) applications were investigated. The results of analytical and simulation studies were studied in order to determine the equivalence between sinusoidal PWM and third harmonic PWM control technologies in relation to the high conversion factor (CF) and total harmonic distortion (THD) of UPS applications. The inverter simulation used a 3-phase 3-wire topology with a 3-level voltage source inverter. PI controller compensators were included in each of the voltage and current controllers. A voltage major loop controller was used to ensure sinusoidal output voltage. The capacitor voltage, inductor current, and load current were used as feedback control signals. Fourier transform equations were used to characterize harmonic components for double variable controlled waveforms. Results of the study demonstrated that THD-PWMs reduced the peak size of the envelope of each phase leg voltage and increased the modulation index without causing modulation. 9 refs., 1 tab., 12 figs.
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.
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.
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.
Indirect Vector Control of Three Phase Induction Motor using PSIM
Directory of Open Access Journals (Sweden)
Nagulapati Kiran
2014-03-01
Full Text Available This paper presents the implementation of indirect vector control of three phase Induction Motor using Hysteresis Band PWM current control and Synchronous Current Control in PSIM environment. In any machine drive system, current control directly influences both flux and torque developed directly. In Hysteresis current control method, actual current tracks the command current within a hysteresis band. There is no difficulty in current control tracking when CEMF is low, but at higher speeds, current controller gets saturated due to higher CEMF and hense becomes difficult to track due to which there will be a phase lag with respect to command current. All such problems are solved using Synchronous Current Control.Â
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.
A Comparative Study of Sinusoidal PWM and Space Vector PWM of a Vector Controlled BLDC Motor
Lydia Anu Jose, K. B. Karthikeyan
2013-01-01
This paper focuses on the vector control of a BLDC motor with two different concepts of Pulse Width Modulation- the Sinusoidal PWM and the Space Vector Modulation strategy. The paper deals with the basics of a BLDC motor, its dynamic modeling and its speed control using two different strategies of Pulse Width Modulation. The vector control is one of the methods used in variable frequency drives or variable speed drives to control the torque (and thus the speed) of three-phase AC electric moto...
A Comparative Study of Sinusoidal PWM and Space Vector PWM of a Vector Controlled BLDC Motor
Directory of Open Access Journals (Sweden)
LYDIA ANU JOSE, K.B.KARTHIKEYAN
2013-06-01
Full Text Available This paper focuses on the vector control of a BLDC motor with two different concepts of Pulse Width Modulation- the Sinusoidal PWM and the Space Vector Modulation strategy. The paper deals with the basics of a BLDC motor, its dynamic modeling and its speed control using two different strategies of Pulse Width Modulation. The vector control is one of the methods used in variable frequency drives or variable speed drives to control the torque (and thus the speed of three-phase AC electric motors by controlling the current. The results prove that the Space Vector Modulation technique helps to improve the performance and thus the efficiency of the system.
Investigation of FPGA Based PWM Control Technique for AC Motors
Directory of Open Access Journals (Sweden)
Valantina Stephen
2013-02-01
Full Text Available This paper proposes a Random Frequency PWM synchronized for a three phase inverter implemented with use of FPGA and applied to a 1-hp induction motor drive system for the reduction of harmonics and improvement of fundamental peak voltage. For providing alternating output voltage with a specific magnitude and frequency to industrial applications, three-phase inverter is preferred. The gating signals to the inverter are produced by means of Random Frequency PWM to significantly reduce harmonics in comparison to currently used PWMs. FPGA is used to produce gating signals to the switches in a three-phase bridge inverter since a faster speed of operation is needed. The simulation is carried on VHSIC Hardware Description Language (VHDL using ModelSim. Then, this VHDL model is imported into Matlab environment and co-simulated using HDL Cosimulation toolbox. The simulation and experimental results are presented with a view to determine whether Random Frequency PWM performs better in terms of fundamental voltage and Total Harmonic Distortion.
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.
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...
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.
Diode-assisted buck-boost voltage source inverters
DEFF Research Database (Denmark)
Gao, F.; Loh, P.C.
2007-01-01
This paper proposes buck-boost voltage source inverters with a unique X-shape diode-capacitor network inserted between inverter circuitry and dc source for producing a large voltage boost gain. Comparing with other voltage buck-boost techniques, the presented topologies with only a little more passive components can significantly enhance voltage boost capability for dc-ac inversion. With different front-end circuitries, the diode-assisted buck-boost inverters can show different operational principle and voltage boost ratio. Carefully analyzing the operational principle for the inherent energy charging and discharging processes of passive components reveals that the dc-link voltage can alternate between two levels, which therefore demonstrate the phenomena that the specified modulation schemes should note. A modulation scheme that can achieve optimized harmonic switching is first designed with symmetrical state placement in each switching sequence to avoid unnecessary voltage stress across both passive and active components. To reduce the total commutation count, the designed modulation scheme is then modified without increasing voltage stress. All theoretical findings were verified experimentally using a number of scale-down laboratory prototypes.
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...
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.
Directory of Open Access Journals (Sweden)
F. J. De la Hidalga-W
2013-01-01
Full Text Available This work shows that the direct PWM output electric signal, with a duty cycle controlled by light intensity, can beobtained using a circuit containing a saw-tooth voltage generator connected in series with a dc voltage source and ametal (semitransparent gate oxide semiconductor capacitor (MOS-C.The internal PWM signal conversion occurs by the use of non-equilibrium physical processes in the semiconductorsubstrate of the MOS-C. The 10-20 V amplitude limited square PWM output signal is obtained by the amplification ofthe sensor signal with a standard 60 dB transimpedance amplifier. The amplified output signal presents positive andnegative PWM waveforms that can be easily separated using diodes. The duty of the positive part is proportional tothe light intensity, whereas the negative part is inversely proportional to the intensity. The frequency operating rangeof this proposed instrument varies from 1 Hz to a few kilohertz. The duty cycle of the PWM output signal varies from2% to 98% when the incident light intensity varies in the microwatts range. These new transducers or sensors couldbe useful for automatic control, robotic applications, dimmer systems, feedback electronic systems, and non-contactoptical position sensing for nulling and centering measurements.
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.
The Application of FPGA in PWM Controlled Resonant Converter for an Ozone Generator
Directory of Open Access Journals (Sweden)
Mochammad Facta
2013-07-01
Full Text Available Pulse Width Modulation (PWM is a very common technique used in many different applications. The Conventional method its generation is the heart of the inverter system. This paper present methodology to generate Sinusoidal PWM (SPWM signal for three-phase inverter based on EP20K200EFC484-2x Altera Field Programmable Gate Array (FPGA. Designing a PWM inverter drive using FPGA has several advantages, such as: it's quick, very modifiable, and very suitable for prototyping. In this paper, the PWM signal is used control switching action conducted by MOSFET as part of power electronics devices in resonant power converter which has 24 volt DC input voltage. As the result, by using resonant oscillation controlled by FPGA the high sinusoidal voltage until 1.0 kV peak-to peak has been generated in the load side.
Directory of Open Access Journals (Sweden)
S. Senguttuvan
2014-08-01
Full Text Available The aim of study of this paper is design and implementation of a simple and efficient soft switched Pulse Width Modulation (PWM for three-phase induction motor drives. Soft-switching techniques have gained popularity in recent times because they offer many advantages over hard-switched Pulse Width Modulated inverters such as higher efficiency, higher power density and better performances. The quasi-resonant DC-link is being designed, the simulation and experimental results prove that it achieves soft switching of all the main switches and resonant circuit switches at the same time it posses all the capabilities of conventional sinusoidal modulated PWM inverter. Finally, the efficiency of the Soft Switched Sinusoidal PWM (SSSPWM inverter calculated from experimental results is compared with the conventional Hard Switched Sinusoidal PWM (HSSPWM inverter, under identical load conditions. It is of great significance to improve the efficiency by reducing switching losses, high power density, high reliability and low electro management interference.
Component-Minimized Buck-Boost Voltage Source Inverters
DEFF Research Database (Denmark)
Gao, F.; Loh, P.C.
2007-01-01
This paper presents the design of buck-boost B4 inverters that can be derived from either ?uk- or SEPIC-derived buck-boost B6 inverters. Unlike traditional inverters, the integration of front-end voltage boost circuitry and inverter circuitry allows it to perform buck-boost voltage inversion. In order to form a distinct neutral potential in the corresponding voltage boost circuitry for correct B4 inverter operation, necessary modifications are derived step by step. The resulted dc networks with symmetrical placement of passive components allow complete charging and equal energy distribution between capacitors. Modulation wise, the proposed buck-boost B4 inverters can be controlled using a carefully designed carrier-based pulse-width modulation (PWM) scheme that will always ensure balanced threephase outputs as desired, while simultaneously achieving minimal voltage stress across semiconductors. Besides the advantage of reduced active components, buck-boost B4 inverters use a little more passive components when compared with buck-boost B6 inverters, which would allow a selectable tradeoff in practice. Moreover, analysis for discontinuous conduction mode of inductor current reveals the additional voltage relationship between dc input and ac output which is beyond the expectation when continuous inductor current is assumed. These theoretical findings, together with the inverter practicality, have been confirmed in Matlab/PLECS simulations and experimentally using laboratory implemented inverter prototypes.
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.
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 propõe uma metodologia de projeto aprimorada para determinação dos componentes auxiliares para o conversor ZVT CC-CC PWM snubber assisted auxiliary switch. O procedimento de projeto proposto é baseado na redução das perdas de condução no circuito auxiliar. Isto é somente possível devido [...] à localização 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 relação 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 relação ao conversor ZVT PWM com fonte auxiliar de tensão 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).
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 propõe uma metodologia de projeto aprimorada para determinação dos componentes auxiliares para o conversor ZVT CC-CC PWM snubber assisted auxiliary switch. O procedimento de projeto proposto é baseado na redução das perdas de condução no circuito auxiliar. Isto é somente possível devido à localização 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 relação 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 relação ao conversor ZVT PWM com fonte auxiliar de tensão constante (true PWM ZVS pole.
Three-phase power supply, output 60v and 100a, with unit power factor and low RFI level
Directory of Open Access Journals (Sweden)
João 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.
Shunt active filter algorithms for a three phase system fed to adjustable speed drive
Directory of Open Access Journals (Sweden)
Sujatha.CH
2011-10-01
Full Text Available This paper presents the simulation of Shunt Active Power filter by using two different control schemes, Indirect current control technique and Synchronous detection technique by using ANN. These two control techniques are working under both balanced and unbalanced three phase voltage source conditions and it is feeding to aadjustable speed drive the torque speed characteristics of a motor is presented. Indirect current control technique is implemented under dynamic load condition and load balanced condition. The equal current distribution method of synchronous detection theory is used here to calculate the three phase compensating currents to be provided by the active filter. For calculating sequence currents neural network is used. Neural network is used for estimation of distorted waves, delay less harmonic filtering.
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.
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
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.
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 propõe dois novos algoritmos de limitação para inversores de tensão trifásicos a quatro braços. Estes baseiam-se na limitação do vetor de comando dentro da região de operação linear do inversor. O primeiro algoritmo utiliza um elipsóide inscrito no dodecaedro definido pelas extremidades [...] dos possíveis vetores de comutação do inversor, e o segundo é baseado nos planos limites desse poliedro. Uma descrição detalhada, abordando os principais pontos requeridos para a implementação digital, da modulação space vector e dos algoritmos de limitação são apresentados. Ainda, as tensões de saída e as correntes nos indutores são dinamicamente reguladas, por meio de servo controladores MIMO em eixos síncronos dq0. Estes controladores são projetados usando a técnica do regulador linear quadrático discreto de regime permanente, o qual assegura estabilidade para o sistema em toda a faixa de operação. Além disso, para prover transições suaves entre os diferentes modos de operação do inversor, são propostos algoritmos MIMO não lineares para limitar a sobrecarga da ação integral, quando o vetor de comando for limitado, e atualizar dinamicamente as variáveis dos servo controladores. Finalmente, são 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.
Four-switch three-phase space-vector PWM AC-DC converter.
Czech Academy of Sciences Publication Activity Database
Klíma, J.; Škramlík, Ji?í; Valouch, Viktor
2008-01-01
Ro?. 95, ?. 4 (2008), s. 383-397. ISSN 0020-7217 Institutional research plan: CEZ:AV0Z20570509 Keywords : AC-DC converter * space-vector pulsewidth modulation * rectifier Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.567, year: 2008
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
Zidani, Fatiha; DIALLO, Demba; Benbouzid, Mohamed; Naït-Saïd, 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 ...
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
Ahmed, Waheed; Usman Ali, Syed M.
2013-12-01
We have performed comparative studies of Space Vector Pulse Width Modulation (SVPWM) and Sinusoidal Pulse Width Modulation (SPWM) techniques utilizing MATLAB tools. During these investigations, we carried out intensive simulations, comprehensively analyzed the obtained results and compared the harmonic density, power factor (PF), & switching losses of SVPWM and SPWM. It has been observed during investigations that if the switching frequency is high then losses due to harmonics are negligible, thus based on obtained results we suggested that the SVPWM technique is a more reliable solution. Because SVPWM utilizes DC bus voltage more efficiently, generates less Total Harmonic Distortion (THD) and has higher output quality it provides flexible control of output voltage and output frequency for Variable Speed Drive (VSD).
P. Rathika; D Devaraj
2011-01-01
This paper presents a fuzzy logic based three phase four wire four-leg shunt active power filter to suppress harmonic currents. Modified instantaneous p-q theory is adopted for calculating the compensating current. Fuzzy-adaptive hysteresis band technique is applied for the current control to derive the switching signals for the voltage source inverter. A fuzzy logic controller is developed to control the voltage of the DC capacitor. Computer simulations are carried out on a sample power syst...
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.
PERFORMANCE ANALYSIS OF SENSORLESS BLDC MOTOR DRIVE SYSTEM USING ASYMMETRIC PWM CONTROL TECHNIQUE
Meenakshi, R.; Sella Kumar, S.; Sasikumar, Dr M.
2012-01-01
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 beca...
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.
A Single Phase to Three Phase PFC Half-Bridge Converter Using BLDC Drive with SPWM Technique.
Srinu Duvvada; Manmadha Kumar B
2014-01-01
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 ach...
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)
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 tensão 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 implementação em tempo real. A operação do retificador com resposta de tempo mínimo é obtida utilizando o método de desacoplamento por retroação de estados no domínio discreto, sem a necessidade de um controlador de corrente adicional no eixo d. Além disso, são desenvolvidos servos controladores de corrente e tensão a fim de garantir fator de deslocamento unitário e regulação de tensão no barramento CC respectivamente. Finalmente, resultados experimentais são 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.
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 señales, y el receptor o dispositivo de salida. Diversos sistemas de control automático o con retroalimentación requieren una señal eléctrica de salida en forma de pulsos con modulac [...] ión en su ancho (PWM). Generalmente la señal analógica de salida se transforma usando un convertidor de señal PWM. En este trabajo se muestra que una señal 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 señal a PWM se logra explotando los procesos físicos fuera de equilibrio que se presentan dentro del sustrato de silicio del MOS-C. La señal cuadrada PWM, cuya amplitud está limitada a 10-20 V, se obtiene mediante la amplificación de la señal de transductor usando un amplificador estándar de transimpedancia de 60 dB. La señal 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 señal 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.
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
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.
Directory of Open Access Journals (Sweden)
M.NEELU KUMAR, P.BHASKARA PRASAD, PADMA LALITHA
2013-11-01
Full Text Available — Artificial neural-networks (ANN are one of those words that are getting fashionable in the new era of technology. Current regulated PWM voltage source inverters used for synchronizing the utility grid with distributed generation source. Using ANN application with hysteresis current controller improving grid stability, active and reactive power control through voltage and frequency control etc., to the utility grid. ANN hysteresis current controller results are compared with conventional hysteresis controller. The studied system is modeled and simulated in the MATLAB.
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.
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.
Control of direct three-phase to single-phase converters under balanced and unbalanced operations
International Nuclear Information System (INIS)
In this paper, a new control method based on pulse width modulation (PWM) technique is presented for direct three-phase to single-phase converters. This control method can be easily developed to direct three-phase to n-phase converters based on the exact principle of operation. The results of the proposed control method have been presented for two conventional topologies of direct three-phase to single-phase converters with four and six power switches. The suggested control method does not depend on the balanced or unbalanced input voltages. In balanced operation, the maximum output/input voltage transfer ratios are 0.5 and 1.5 for converters with four and six power switches, respectively. Also, the proposed method has no restrictions in frequency transformation. Another advantage of the proposed control method in comparison with the conventional control methods is dv/dt reduction in switches and loads. The operation and performance of the proposed control method has been verified by the simulation and experimental results.
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.
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.
Three-phase Brushless DC Motor Control
Fang, Xinwei
2012-01-01
With the increasing demand of using electric power and unpleasant of using brush motor; the usage of Three-phase Brushless Motor has been significantly developed in industry. However, with market-standard motor driver, there are many inconveniences for small institutions or companies in either application developments or education purposes. For instance, the size and the price of driver. Therefore, the object of this thesis was design modular sections (Software program, PCB driver and PCB con...
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...
Performance Evaluation of Three Phase Bridge Module Type Diode Clamped Multilevel Inverter
Directory of Open Access Journals (Sweden)
C.R. Balamurugan, S. P. Natarajan, R.Bensraj
2012-06-01
Full Text Available This work proposes three phase five level Bridge module type Diode Clamped Multilevel Inverter (DCMLI using various modulating techniques for induction motor load. These Pulse Width Modulating (PWM techniques include Carrier Overlapping (CO strategy, Variable Frequency (VF strategy, Phase Shift (PS strategy and Sub-Harmonic Pulse Width Modulation (SHPWM i.e. Phase Disposition (PD strategy, Phase Opposition Disposition (POD strategy and Alternate Phase Opposition Disposition (APOD strategy. The Total Harmonic Distortion (THD, VRMS (fundamental, crest factor, form factor and distortion factor are evaluated for various modulation indices. Simulation is performed using MATLAB-SIMULINK. It is observed thatPODPWM/PSPWM methods provide output with relatively low distortion for R Load. It is also observed that PSPWM method provides output with relatively low distortion for IM load. COPWM is also found to perform better since it provides relatively higher fundamental RMS output voltage for Induction Motor (IM load and R load.
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.
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
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
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...
Blahník, Vojt?ch; Peroutka, Zden?k; Talla, Jakub
2014-03-01
This paper introduces the advanced control of single-phase voltage-source active rectifier. This control provide direct control of trolley-wire current and active damping of low-frequency disturbances at the converter ac side. Our proposed control strategy combines PR controller with feed-forward model and low-frequency harmonic compensator based on resonant controllers. Achieved experimental results show excellent converter behavior, where converter is fed by strongly distorted supply voltage.
Rabie, Amiri; Karim, Fellah Mohammed; Samir, Hadjeri; Ahmed, Zidi Sid; Mohamed, Khatir
2009-01-01
Voltage Source Converter (VSC) based HVDC transmission technology hasbeen selected as the basis for several recent projects due to its controllability,compact modular design, ease of system interface, and low environmentalimpact. This paper investigates the dynamic performance of a 200MW,±100kV VSC-HVDC transmission system under some faulted conditionsusing MATLAB/Simulink. Simulation results confirm the satisfactoryperformance of the proposed system under active and reactive powervariations...
Directory of Open Access Journals (Sweden)
Amiri RABIE
2009-12-01
Full Text Available Voltage Source Converter (VSC based HVDC transmission technology hasbeen selected as the basis for several recent projects due to its controllability,compact modular design, ease of system interface, and low environmentalimpact. This paper investigates the dynamic performance of a 200MW,±100kV VSC-HVDC transmission system under some faulted conditionsusing MATLAB/Simulink. Simulation results confirm the satisfactoryperformance of the proposed system under active and reactive powervariations and fault conditions.
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.
Resonant Demagnetization PWM Forward Converter
B?LG?N, Bülent
2003-01-01
In this paper, a new approach to demagnetization process of a PWM forward converter (FC) is proposed. According to this approach, the demagnetization winding and diode of a conventional FC are removed, and an external capacitor is added in parallel with the secondary diode. This replacement changes the linear demagnetization process of a conventional FC into a resonant demagnetization process. The theoretical performance results of the proposed resonant demagnetization forward conve...
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).
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)
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.
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)
Low-cost PWM speed controller for an electric mini-baja type vehicle
Directory of Open Access Journals (Sweden)
Samuel Euzédice de Lucena
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.
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.
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.
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
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 tensões senoidais através de modulação por largura de pulso (PWM) digital. O propósito desta metodologia é o de determinar os parâmetros do filtro que assegure a especif [...] icação da máxima taxa de distorção harmônica total (THD) admissível nas tensões de saída do inversor PWM, para cargas lineares e não-lineares. A metodologia proposta é discutida em detalhes, incluindo a descrição das etapas necessárias para a derivação do procedimento de projeto para diferentes topologias de inversores de tensão e o procedimento para obtenção das curvas necessárias para o projeto. Finalizando, são apresentados alguns exemplos de projeto para topologias de inversores monofásicos e trifásicos com saída a três fios e a quatro fios. Resultados experimentais são 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.
Design, Control, and Modeling of a New Voltage Source Converter for HVDC System
Mohan, Madhan; Singh, Bhim; Ketan Panigrahi, Bijaya
2013-05-01
Abstract: A New Voltage Source Converter (VSC) based on neutral clamped three-level circuit is proposed for High Voltage DC (HVDC) system. The proposed VSC is designed in a multipulse configuration. The converter is operated by Fundamental Frequency Switching (FFS). A new control method is developed for achieving all the necessary control aspects of HVDC system such as independent real and reactive power control, bidirectional real and reactive power control. The basic of the control method is varying the pulse width and by keeping the dc link voltage constant. The steady state and dynamic performances of HVDC system interconnecting two different frequencies network are demonstrated for active and reactive power control. Total number of transformers used in this system are reduced to half in comparison with the two-level VSCs for both active and reactive power control. The performance of the HVDC system is improved in terms of reduced harmonics level even at fundamental frequency switching. The harmonic performance of the designed converter is also studied for different value of the dead angle (?), and the optimized range of the dead angle is achieved for varying reactive power requirement. Simulation results are presented for the designed three level multipulse voltage source converters with the proposed control algorithm.
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.
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.
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)
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.
Simulation of Five Phase Voltage Source Inverter with Different Excitation for Star Connected Load
Directory of Open Access Journals (Sweden)
M.A Inayathullaah
2014-07-01
Full Text Available In order to reduce the torque ripple and harmonics for smooth operation of the machine and to reduce the amount of heat generated the motor has to be supplied with multi phase supply greater than three phase supply. Selection of even number of phases should be avoided, because it decreases the performance of the motor as poles coincide with each other. So, Five Phase Supply is preferred. A five phase five leg 10 switch inverter fed five phase star connected load operating with five different excitation is simulated and compared with that of three phase conventional inverter.
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
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.
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.
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
Influence of current limitation on voltage stability with voltage sourced converter HVDC
DEFF Research Database (Denmark)
Zeni, Lorenzo; Jóhannsson, Hjörtur
2013-01-01
A first study of voltage stability with relevant amount of Voltage Sourced Converter based High Voltage Direct Current (VSC-HVDC) transmission is presented, with particular focus on the converters’ behaviour when reaching their rated current. The detrimental effect of entering the current limitation on the Power-Voltage (PV) curves at a load bus is exemplified on a three-bus system, proposing a method to model the converters in current limiting mode through ideal current sources. The influence of the current magnitude and angle on the reduced stability margin is analysed and results show that, when the current limit is reached, despite the detrimental effect brought about by an increased equivalent transmission impedance, the loss of stability margin can be minimised by proper control of the converter.
Influence of current limitation on voltage stability with Voltage Sourced Converter HVDC
DEFF Research Database (Denmark)
Zeni, Lorenzo; Johannsson, Hjortur
2013-01-01
A first study of voltage stability with relevant amount of Voltage Sourced Converter based High Voltage Direct Current (VSC-HVDC) transmission is presented, with particular focus on the converters' behaviour when reaching their rated current. The detrimental effect of entering the current limitation on the Power-Voltage (PV) curves at a load bus is exemplified on a three-bus system, proposing a method to model the converters in current limiting mode through ideal current sources. The influence of the current magnitude and angle on the reduced stability margin is analysed and results show that, when the current limit is reached, despite the detrimental effect brought about by an increased equivalent transmission impedance, the loss of stability margin can be minimised by proper control of the converter.
Konishi, Hiroo; Takahashi, Choei; Kishibe, Hideto; Sato, Hiromichi
The stable operating power limits of a small scale HVDC system composed of voltage source converters (VSC-HVDC system) are analyzed with a simple model. The VSC-HVDC system could operate where the AC system must be somewhat larger in capacity than the VSC-HVDC system capacity. The stable operating power limits were between one and two times the SCR (short circuit ratio). When the inverter of the VSC-HVDC system was operated with lead reactive (capacitive) power control conditions, the stable operating limits were increased through AC voltage stabilization. When the inverter was a STATCOM operation, it could operate regardless of the SCR but regions within allowable AC voltage variations.
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.
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.
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.
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.)
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.
International Nuclear Information System (INIS)
This paper focuses on the detection of a rotor cage fault in a three-phase PWM feed induction motor. In inverter-fed machines there are some difficulties for the detection of a rotor cage fault. These difficulties are due to the fault signature that will be contained in the currents or voltages applied to the machine. In this way, a new approach based on the current and a virtual flux is proposed. The use of the virtual flux allows the improving of the signal to noise ratio. This approach also allows the identification of a rotor cage fault independently of the type of control used in the ac drive. The theoretical principle of this method is discussed. Simulation and experimental results are presented in order to show the effectiveness of the proposed approach
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.
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 propõe uma solução para a conexão direta de geradores de indução trifásicos em uma rede monofásica com regulação de vazão o que faz com que, a velocidade do gerador de indução se mantenha acima de sua velocidade síncrona. Para que a conexão 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 tensão sintetizada pelo conversor em relação a tensão da rede monofásica de forma que o fator de potência na rede monofásica seja unitário. Em relação ao conversor de potência, espera-se que o mesmo produza tensões senoidais, com freqüência e amplitude fixas para que o gerador de indução 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.
Directory of Open Access Journals (Sweden)
Ricardo Q. Machado
2009-09-01
Full Text Available 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.Este artigo propõe uma solução para a conexão direta de geradores de indução trifásicos em uma rede monofásica com regulação de vazão o que faz com que, a velocidade do gerador de indução se mantenha acima de sua velocidade síncrona. Para que a conexão entre gerador e rede monofásica seja satisfatória 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 tensão sintetizada pelo conversor em relação a tensão da rede monofásica de forma que o fator de potência na rede monofásica seja unitário. Em relação ao conversor de potência, espera-se que o mesmo produza tensões senoidais, com freqüência e amplitude fixas para que o gerador de indução opere balanceado. O artigo descreve a estratégia de controle do inversor, o critério de projeto dos controladores e apresenta alguns resultados experimentais.
Push-Pull Converter Fed Three-Phase Inverter for Residential and Motor Load
Directory of Open Access Journals (Sweden)
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.
Energy Technology Data Exchange (ETDEWEB)
Singh, Bhim; Kasal, Gaurav Kumar [Department of Electrical Engineering, Indian Institute of Technology, Delhi, Hauz-Khas, New Delhi 110016 (India)
2008-06-15
This paper deals with a neural network-based solid state voltage controller for an isolated asynchronous generator (IAG) driven by constant speed prime mover like diesel engine, bio-gas or gasoline engine and supplying three-phase four-wire loads. The proposed control scheme uses an indirect current control and a fast adaptive linear element (adaline) based neural network reference current extractor, which extracts the real positive sequence current component without any phase shift. The neutral current of the source is also compensated by using three single-phase bridge configuration of IGBT (insulated gate bipolar junction transistor) based voltage source converter (VSC) along-with single-phase transformer having self-supported dc bus. The proposed controller provides the functions as a voltage regulator, a harmonic eliminator, a neutral current compensator, and a load balancer. The proposed isolated electrical system with its controller is modeled and simulated in MATLAB along with Simulink and PSB (Power System Block set) toolboxes. The simulated results are presented to demonstrate the capability of an isolated asynchronous generating system driven by a constant speed prime mover for feeding three-phase four-wire loads. (author)
Nonlinear control of voltage source converters in AC-DC power system.
Dash, P K; Nayak, N
2014-07-01
This paper presents the design of a robust nonlinear controller for a parallel AC-DC power system using a Lyapunov function-based sliding mode control (LYPSMC) strategy. The inputs for the proposed control scheme are the DC voltage and reactive power errors at the converter station and the active and reactive power errors at the inverter station of the voltage-source converter-based high voltage direct current transmission (VSC-HVDC) link. The stability and robust tracking of the system parameters are ensured by applying the Lyapunov direct method. Also the gains of the sliding mode control (SMC) are made adaptive using the stability conditions of the Lyapunov function. The proposed control strategy offers invariant stability to a class of systems having modeling uncertainties due to parameter changes and exogenous inputs. Comprehensive computer simulations are carried out to verify the proposed control scheme under several system disturbances like changes in short-circuit ratio, converter parametric changes, and faults on the converter and inverter buses for single generating system connected to the power grid in a single machine infinite-bus AC-DC network and also for a 3-machine two-area power system. Furthermore, a second order super twisting sliding mode control scheme has been presented in this paper that provides a higher degree of nonlinearity than the LYPSMC and damps faster the converter and inverter voltage and power oscillations. PMID:24906895
Dai, NingYi; Lam, Chi-Seng; Zhang, WenChen
2014-01-01
In order to utilize the energy from the renewable energy sources, power conversion system is necessary, in which the voltage source inverter (VSI) is usually the last stage for injecting power to the grid. It is an economical solution to add the function of power quality conditioning to the grid-connected VSI in the low-voltage distribution system. Two multifunctional VSIs are studied in this paper, that is, inductive-coupling VSI and capacitive-coupling VSI, which are named after the fundamental frequency impedance of their coupling branch. The operation voltages of the two VSIs are compared when they are used for renewable energy integration and power quality conditioning simultaneously. The operation voltage of the capacitive-coupling VSI can be set much lower than that of the inductive-coupling VSI when reactive power is for compensating inductive loads. Since a large portion of the loads in the distribution system are inductive, the capacitive-coupling VSI is further studied. The design and control method of the multifunctional capacitive-coupling VSI are proposed in this paper. Simulation and experimental results are provided to show its validity. PMID:25177725
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.
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.
7 CFR 3403.4 - Three-phase program.
2010-01-01
...STATE RESEARCH, EDUCATION, AND EXTENSION SERVICE, DEPARTMENT OF AGRICULTURE SMALL BUSINESS INNOVATION RESEARCH GRANTS PROGRAM Program Description...Three-phase program. The Small Business Innovation Research Grants Program is...
Scientific Electronic Library Online (English)
C, Núñez-Gutiérrez; J, Lira-Pérez; V.M., Cárdenas-Galindo; R, Alvarez-Salas.
2009-03-01
Full Text Available Este trabajo presenta la aplicación de un procesador digital de señales (DSP) para el control de un rectificador PWM trifásico para aplicaciones industriales, al cual se le amplían sus funciones para tener capacidad de compensar caídas de voltaje instantáneas. El estudio resalta las ventajas que ofr [...] ece el DSP para controlar el rectificador haciendo uso de la transformación del sistema de un marco de referencia fijo a uno síncrono (teoría D-Q) y controladores clásicos. Se presenta el análisis del sistema, así como resultados de simulación y experimentales para validar la operación del DSP como elemento controlador del sistema. Abstract in english This work presents the application of a digital signal processor (DSP) for the control of a three-phase PWM rectifier for industrial applications, to which are extended their functions to have capacity to compensate voltage sags. The study stands out the advantages that the DSP offers to control, ba [...] sed on the system transformation from fix reference frame to synchronous reference frame (D-Q theory) and classical controllers. The analysis of the system is presented, as well as simulation and experimental results to validate the operation of the DSP as system element controller.
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
A novel approach for pulsed high-power high-tension voltage source with inductive energy storage
International Nuclear Information System (INIS)
This paper introduces a novel approach for the pulsed high-power high-tension voltage source with inductive energy storage developed for auxiliary heat system in fusion engineering. The technical design of a prototype for 1 MW IC RH system and the principle experiment results are given. This new type power HV modulator is rather attractive because of its simplicity of construction, ease of maintenance, high reliability, low cost, low influence for local network
A New Generalized Discontinuous-PWM Strategy for Active Power Filters
DEFF Research Database (Denmark)
Asiminoaei, Lucian; Rodriguez, Pedro
2007-01-01
Classical discontinuous pulse width modulations (DPWM's) may not be efficiently applied in active power filters, because it is hard to predict the peak values of the inverter current, and consequently it is difficult to calculate the position of the clamped interval, that minimizes the switching losses in any operating point. This paper proposes a new discontinuous pulse width modulation strategy applied to shunt active power filters. The proposed modulation strategy detects the current vector position relative to the inverter voltage reference and determines instantaneously the optimum clamped duration on each phase. It achieves a clamped voltage pattern, with variable lengths depending on the magnitude of the inverter current. This property adaptively reduces the current stress and minimizes the inverter switching losses, regardless of its application. The proposed modulation strategy is described, analyzed and validated on a three-phase voltage source inverter, rated at 7 kVA, 400 V, controlled as an active power filter.
Liang, Yiqiao
Reactive power compensation and harmonic reduction are two relevant research problems that exist in modern electric power systems. With the advancement of modern power electronics technology in both circuits and devices, new and better solutions are being proposed and applied to solve these two problems. To compensate reactive power, a cascading voltage source inverter with a Phase-Shift, Unipolar SPWM switching scheme is proposed. The main circuit of this inverter is composed of several identical voltage source H-bridge inverters connected in cascade form. Advantages of this scheme include use of identically rated storage capacitors, similarly rated switches and diodes, quick system response to load changes, and easily achievable redundancy. To solve the harmonic reduction problem, the flying capacitor multilevel voltage source inverter is adopted to construct a novel power line conditioner. The Phase Shift SPWM switching scheme is also employed to operate the switches of this inverter. As a result, it is possible to extend the new power line conditioner to distribution systems or industrial applications where voltage usually ranges from 4.16kV to 13.8kV. It is shown that the proposed power line conditioner not only balances the unbalanced load, but simultaneously compensates the reactive power as well.
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.
An improved fault-tolerant control scheme for PWM inverter-fed induction motor-based EVs.
Tabbache, Bekheïra; 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
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
Directory of Open Access Journals (Sweden)
P. Rathika
2011-09-01
Full Text Available This paper presents a fuzzy logic based three phase four wire four-leg shunt active power filter to suppress harmonic currents. Modified instantaneous p-q theory is adopted for calculating the compensating current. Fuzzy-adaptive hysteresis band technique is applied for the current control to derive the switching signals for the voltage source inverter. A fuzzy logic controller is developed to control the voltage of the DC capacitor. Computer simulations are carried out on a sample power system to demonstrate the suitability of the proposed control strategy, for harmonic reduction under three different conditions namely, ideal, unbalance, unbalance and distorted source voltage conditions. The proposed control strategy is found to be effective to reduce the harmonics and compensate reactive power and neutral current and balance load currents under ideal and non-ideal source voltage conditions.
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.
Zhang, Jianghan; Luo, Hui; Zhao, Jin; Wu, Feng
2015-02-01
This paper develops a novel method for the detection and isolation of open-transistor faults in voltage-source inverters feeding induction motors. Based on analyzing the load currents trajectories after Concordia transformation, six diagnostic signals each of which indicates a certain switch are extracted and a fuzzy rule base is designed to perform fuzzy reasoning in order to detect and isolate 21 fault modes including single- and double-transistor faults. In addition, the fuzzy rules are rearranged and each of them is set to a reasonable value representing the fault modes. The simulation and experiment are carried out to demonstrate the effectiveness of the proposed fuzzy approach.
Capillary instability in models for three-phase flow
Azevedo, A. V.; Marchesin, D.; Plohr, B.; Zumbrun, K.
Standard models for immiscible three-phase flow in porous media exhibit unusual behavior associated with loss of strict hyperbolicity. Anomalies were at one time thought to be confined to the region of nonhyperbolicity, where the purely convective form of the model is ill-posed. However, recent results have revealed that diffusion terms, which are usually neglected, can have a significant effect. The delicate interplay between convection and diffusion determines a larger region of diffusive linear instability. For artificial and numerical diffusion, these two regions usually coincide, but in general they do not.Accordingly, in this paper, we investigate models of immiscible three-phase flow that account for the physical diffusive effects caused by capillary pressure differences among the phases. Our results indicate that, indeed, the locus of instability is enlarged by the effects of capillarity, which therefore entails complicated behavior even in the region of strict hyperbolicity. More precisely, we demonstrate the following results.(1) For general immiscible three-phase flow models, if there is stability near the boundary of the saturation triangle, then there exists a Dumortier-Roussarie-Sotomayor (DRS) bifurcation point within the region of strict hyperbolicity. Such a point lies on the boundary of the diffusive linear instability region. Moreover, as we have shown in previous works, existence of a DRS point (satisfying certain nondegeracy conditions) implies nonuniqueness of Riemann solutions, with corresponding nontrivial asymptotic dynamics at the diffusive level and ill-posedness for the purely convective form of the equations.(2) Models employing the interpolation formula of Stone (1970) to define the relative permeabilities can be linearly unstable near a corner of the saturation triangle. We illustrate this instability with an example in which the two-phase permeabilities are quadratic.Results (1) and (2) are obtained as consequences of more general theory concerning Majda-Pego stability and existence of DRS points, developed for any two-component system and applied to three-phase flow. These results establish the need for properly modelling capillary diffusion terms, for they have a significant influence on the well-posedness of the initial-value problem. They also suggest that generic immiscible three-phase flow models, such as those employing Stone permeabilities, are inadequate for describing three-phase flow.
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.
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.
Backstepping controller of five-level three-phase inverter
Directory of Open Access Journals (Sweden)
Majdoul R.
2014-01-01
Full Text Available Multilevel converters are becoming increasingly used in many industrial applications due to the many advantages that they offer. The improvements in the output signal quality, lower Total Harmonic Distortion (THD and many other properties make multilevel converters very attractive for connecting photovoltaic generators to medium voltage grid directly or to be used in a local power supply. In this paper, we focus on the implementation of a three-phase five-level diode clamped inverter and design of a performing nonlinear controller using the Backstepping approach. The control objective is to generate, at the system output, sinusoidal three-phase voltages with amplitude and frequency fixed by the reference signal independently of load variations. The performance study of the multilevel inverter and the designed controller are made by simulations in Matlab/Simulink environment.
Direct Torque Control of Three-Phase Flux Reversal Machine
D S Phani Gopal Cheerla, L. Malleswari
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.
Nonlinear acoustic wave generation in a three-phase seabed
Kukarkin, A. B.; Pushkina, N. I.; Zhileikin, Ya M.
2015-01-01
Generation of an acoustic wave by two pump sound waves is studied in a three-phase marine sediment that consists of a solid frame and the pore water with air bubbles in it. To avoid shock-wave formation the interaction is considered in the frequency range where there is a significant amount of sound velocity dispersion. Nonlinear equations are obtained to describe the interaction of acoustic waves in the presence of air bubbles. An expression for the amplitude of the generat...
CONCEPTUAL THREE PHASE KDD MODEL AND FINANCIAL RESEARCH
Directory of Open Access Journals (Sweden)
Dr. Simmi Bagga
2013-02-01
Full Text Available KDD model becomes used in financial process. Data Mining tools can be used to improve the efficiency of the professionals. The integration of Data Mining tools with the traditional financial research methods is relatively a new concept. If Data Mining tools for Financial are developed then it make the process fast, cheaper and relatively much more efficient. In this paper we have discussed the three phase model of KDD on Financial Research.
Direct Torque Control of Three-Phase Flux Reversal Machine
Directory of Open Access Journals (Sweden)
D S PHANI GOPAL CHEERLA, L.MALLESWARI, DR. G R K MURTHY
2013-05-01
Full Text Available 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.
Advanced nonlinear control of three phase series active power filter
Abouelmahjoub Y.; Abouloifa A.; Giri F.; Chaoui F.Z.; Kissaoui M.
2014-01-01
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 ...
Acoustic wave front reversal in a three-phase media
Pushkina, N. I.
2015-01-01
Acoustic wave front conjugation 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...
Three Phase High Power Quality Two- Stage Boost Rectifier
Nammalvar, P.; Annapoorani, S.
2012-01-01
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 co...
Evaluation of Three-Phase Transformerless Photovoltaic Inverter Topologies
Kerekes, Tamas; Liserre, Marco; Teodorescu, Remus; Klumpner, C.; Sumner, M.
2009-01-01
This paper analyzes and compares three transformerless photovoltaic inverter topologies for three-phase grid connection with the main focus on the safety issues that result from the lack of galvanic isolation. A common-mode model, valid at frequencies lower than 50 kHz, is adopted to study the leakage current paths. The model is validated by both simulation and experimental results. These will be used to compare the selected topologies, and to explain the influence of system unbalance and the...
Precise derating of three phase induction motors with unbalanced voltages
International Nuclear Information System (INIS)
Performance analysis of three phase induction motors under supply voltage unbalance conditions is normally conducted using the well-known symmetrical components analysis. In this analysis, the voltage unbalance level at the terminals of the machine is assessed by means of the NEMA or IEC definitions. Both definitions lead to a relatively large error in predicting the performance of a machine. A method has recently been proposed in which, in addition to the voltage unbalance factor (VUF), the phase angle has been taken into account in the analysis. This means that the voltage unbalance factor is regarded as a complex value. This paper shows that although the use of the complex VUF reduces the computational error considerably, it is still high. This is proven by evaluating the derating factor of a three phase induction motor. A method is introduced to determine the derating factor precisely using the complex unbalance factor for an induction motor operating under any unbalanced supply condition. A practical case for derating of a typical three phase squirrel cage induction motor supplied by an unbalanced voltage is studied in the paper
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.
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 implementação experimental de um conversor trifásico em matriz. As chaves bidirecionais empregadas na construção do protótipo foram construídas com a utilização de componentes discretos como IGBT's e diodos rápidos. Aspectos relacionados a proteção con [...] tra sobre tensão e curto circuito, processo de comutação das chaves bidirecionais e filtro de entrada são apresentados neste trabalho juntamente com resultados experimentais da operação 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.
Directory of Open Access Journals (Sweden)
Milton E. de Oliveira Filho
2012-06-01
Full Text Available 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-directional switches, and input filter are addressed in this paper.Este trabalho apresenta aspectos relacionados a implementação experimental de um conversor trifásico em matriz. As chaves bidirecionais empregadas na construção do protótipo foram construídas com a utilização de componentes discretos como IGBT's e diodos rápidos. Aspectos relacionados a proteção contra sobre tensão e curto circuito, processo de comutação das chaves bidirecionais e filtro de entrada são apresentados neste trabalho juntamente com resultados experimentais da operação do conversor.
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
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.
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.
Nonlinear acoustic wave generation in a three-phase seabed
Kukarkin, A B; Zhileikin, Ya M
2015-01-01
Generation of an acoustic wave by two pump sound waves is studied in a three-phase marine sediment that consists of a solid frame and the pore water with air bubbles in it. To avoid shock-wave formation the interaction is considered in the frequency range where there is a significant amount of sound velocity dispersion. Nonlinear equations are obtained to describe the interaction of acoustic waves in the presence of air bubbles. An expression for the amplitude of the generated wave is obtained and numerical analysis of its dependence on distance and on the resonance frequency of bubbles is performed.
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.)
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.
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.
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
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.
Experimental dynamic evaluation of three-phase reactors
Scientific Electronic Library Online (English)
F. G., Sales; L. C. A., Maranhão; 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.
Three-phase bone scintigraphy of Kienboeck disease
International Nuclear Information System (INIS)
Thirty-three joints in 31 patients with Kienboeck disease were evaluated with three-phase bone scintigraphy. Follow-up studies were performed in 19 cases of them. The patients with increased ulnar blood flow on arterial phase and ample perfusion on venous phase in angiograms showed good clinical prognosis. This ample ulnar blood flow and perfusion might be essential for the recovery of this disease. Although staging was possible using static images alone, blood pool images provided more information about the present condition of lesions, such as hyperemic state and remodeling reactions. Blood pool image was indispensable for staging and analyzing lesions and evaluating post-operative course. Increased lunate perfusion in venous phase of angiograms and localized lunate uptake in blood pool images were the favorable signs, which were shown in most cases with good prognosis. It is concluded that three-phase bone scintigraphy gives useful information for evaluating Kienboeck disease which can not be obtained by conventional bone scintigraphy. (author)
Three phase skeletal scintigraphy for evaluation of composite tissue grafts
International Nuclear Information System (INIS)
Three phase skeletal scintigraphy consisting of a radionuclide angiogram, and early post-injection ''blood pool'' image, and images obtained three to four hours after injection was performed in five patients to evaluate the viability of free composite tissue grafts of the tensor fascha lata or the lattissimus dorsi. In four of five patients who showed normal perfusion pattern during the radionuclide angiogram and normal soft tissue distribution of tracer during the ''blood pool'' image viabiliy of the graft was correctly determined. The one patient who showed a normal perfusion pattern in the radionuclide angiogram with absence of tissue perfusion seen in the ''blood pool'' image went on to develop gangrene and infection of the composite tissue graft. Normal metabolic bone activity was shown in the delayed images of those patients who had successful grafts which included bony structures. Three phase radionuclide imaging therefore appears to be of value in evaluating composite tissue grafts and has predictive value in assessing post-operative graft viability
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
Advanced computational model for three-phase slurry reactors
International Nuclear Information System (INIS)
In the second year of the project, the Eulerian-Lagrangian formulation for analyzing three-phase slurry flows in a bubble column is further developed. The approach uses an Eulerian analysis of liquid flows in the bubble column, and makes use of the Lagrangian trajectory analysis for the bubbles and particle motions. An experimental set for studying a two-dimensional bubble column is also developed. The operation of the bubble column is being tested and diagnostic methodology for quantitative measurements is being developed. An Eulerian computational model for the flow condition in the two-dimensional bubble column is also being developed. The liquid and bubble motions are being analyzed and the results are being compared with the experimental setup. Solid-fluid mixture flows in ducts and passages at different angle of orientations were analyzed. The model predictions were compared with the experimental data and good agreement was found. Gravity chute flows of solid-liquid mixtures is also being studied. Further progress was also made in developing a thermodynamically consistent model for multiphase slurry flows with and without chemical reaction in a state of turbulent motion. The balance laws are obtained and the constitutive laws are being developed. Progress was also made in measuring concentration and velocity of particles of different sizes near a wall in a duct flow. The technique of Phase-Doppler anemometry was used in these studies. The general objective of this project is to provide the needed fundamental understanding of three-phase slurry reactors in Fischer-Tropsch (F-T) liquid fuel synthesis. The other main goal is to develop a computational capability for predicting the transport and processing of three-phase coal slurries. The specific objectives are: (1) To develop a thermodynamically consistent rate-dependent anisotropic model for multiphase slurry flows with and without chemical reaction for application to coal liquefaction. Also establish the material parameters of the model. (2) To provide experimental data for phasic fluctuation and mean velocities, as well as the solid volume fraction in the shear flow devices. (3) To develop an accurate computational capability incorporating the new rate-dependent and anisotropic model for analyzing reacting and nonreacting slurry flows, and to solve a number of technologically important problems related to Fischer-Tropsch (F-T) liquid fuel production processes. (4) To verify the validity of the developed model by comparing the predicted results with the performed and the available experimental data under idealized conditions
Intelligent Positioning Fuzzy Servomechanism Under PWM Nonlinear Loads
Scientific Electronic Library Online (English)
D., Rangel; A. L., Rivera; P.D., Alaníz; R., Castañeda; V.M., Castaño.
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.
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.
Evaluation of Three-Phase Transformerless Photovoltaic Inverter Topologies
DEFF Research Database (Denmark)
Kerekes, Tamas; Liserre, Marco
2009-01-01
This paper analyzes and compares three transformerless photovoltaic inverter topologies for three-phase grid connection with the main focus on the safety issues that result from the lack of galvanic isolation. A common-mode model, valid at frequencies lower than 50 kHz, is adopted to study the leakage current paths. The model is validated by both simulation and experimental results. These will be used to compare the selected topologies, and to explain the influence of system unbalance and the neutral conductor inductance on the leakage current. It will be demonstrated that the later has a crucial influence. Finally, a comparison of the selected topologies is carried out, based on the adopted modulation, connection of the neutral and its inductance, effects of unbalance conditions, component ratings, output voltage levels, and filter size. Udgivelsesdato: September
Novel Three-Phase Clustering based on Support Vector Technique
Directory of Open Access Journals (Sweden)
Ping Ling
2013-04-01
Full Text Available As an important issue of machine learning, clustering receives much care in recent years. Among all clustering approaches, most of them conduct clustering operations on overall data. That is, they learn label information from all data. That comes across critical challenge in times of high-sized datasets. This paper proposes a novel Three-phase Labeling algorithm (TPL based on SVC to overcome this problem. TPL consists of selecting data representatives (Data representatives, clustering (Data representatives and then classifying non-Data representatives respectively. Support vector clustering process is modified to select qualified Data representatives in first phase. Spectrum technique governs the second-phase clustering task. Therein, the geometric properties of feature space, a new metric, and a tuning strategy of Kernel scale are used. In experiments on real datasets, TPL achieves clear improvement in accuracy and efficiency over its counterparts, and demonstrates highly competitive clustering performance in comparison with some state of the arts.
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.
Structure of barium in three phases under pressure
Jona, F.; Marcus, P. M.
2006-04-01
A first-principles calculation of the structure of barium under pressure was done with a procedure which finds the equilibrium structure by minimizing the Gibbs free energy at zero temperature with respect to structure at each pressure. The calculated structures agree with measurements at the 1% level in three phases, Ba I (body-centered cubic), Ba II and V (hexagonal close-packed), over a range of pressure from 0 to 900 kbar. The fit to experiment is closer than that of two previous calculations, one of which used molecular dynamics under an applied stress to find equilibrium structure, and the other minimized the energy at constant volume. Hexagonal close-packed barium is shown to be metastable in the pressure range of the incommensurate Ba IV phase.
Three-Phase Unbalanced Load Flow Tool for Distribution Networks
DEFF Research Database (Denmark)
Demirok, Erhan; Kjær, SØren BækhØj
2012-01-01
This work develops a three-phase unbalanced load flow tool tailored for radial distribution networks based on Matlab®. The tool can be used to assess steady-state voltage variations, thermal limits of grid components and power losses in radial MV-LV networks with photovoltaic (PV) generators where most of the systems are single phase. New ancillary service such as static reactive power support by PV inverters can be also merged together with the load flow solution tool and thus, the impact of the various reactive power control strategies on the steady-state grid operation can be simply investigated. Performance of the load flow solution tool in the sense of resulting bus voltage magnitudes is compared and validated with IEEE 13-bus test feeder.
One dimensional speckle fields generated by three phase level diffusers
International Nuclear Information System (INIS)
Speckle patterns have usually been obtained by using ground glass as random diffusers. Liquid-crystal spatial light modulators have opened the possibility of engineering tailored speckle fields obtained from designed diffusers. In this work, one-dimensional Gaussian speckle fields with fully controllable features are generated. By employing a low-cost liquid-crystal spatial light modulator, one-dimensional three phase level diffusers are implemented. These diffusers make it possible to control average intensity distribution and statistical independence among the generated patterns. The average speckle size is governed by an external slit pupil. A theoretical model to describe the generated speckle patterns is developed. Experimental and theoretical results confirming the generation of one-dimensional speckle fields are presented. Some possible applications of these speckles, such as atom trapping and super-resolution imaging, are briefly envisaged. (paper)
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.
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)
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.
One dimensional speckle fields generated by three phase level diffusers
Cabezas, L.; Amaya, D.; Bolognini, N.; Lencina, A.
2015-02-01
Speckle patterns have usually been obtained by using ground glass as random diffusers. Liquid-crystal spatial light modulators have opened the possibility of engineering tailored speckle fields obtained from designed diffusers. In this work, one-dimensional Gaussian speckle fields with fully controllable features are generated. By employing a low-cost liquid-crystal spatial light modulator, one-dimensional three phase level diffusers are implemented. These diffusers make it possible to control average intensity distribution and statistical independence among the generated patterns. The average speckle size is governed by an external slit pupil. A theoretical model to describe the generated speckle patterns is developed. Experimental and theoretical results confirming the generation of one-dimensional speckle fields are presented. Some possible applications of these speckles, such as atom trapping and super-resolution imaging, are briefly envisaged.
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
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.
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.)
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)
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.
Three-phase flow simulations in discrete fracture networks
Geiger, S.; Niessner, J.; Matthai, S. K.; Helmig, R.
2006-12-01
Fractures are often the key conduits for fluid flow in otherwise low permeability rocks. Their presence in hydrocarbon reservoirs leads to complex production histories, unpredictable coupling of wells, rapidly changing flow rates, possibly early water breakthrough, and low final recovery. Recently, it has been demonstrated that a combination of finite volume and finite element discretization is well suited to model incompressible, immiscible two-phase flow in 3D discrete fracture networks (DFN) representing complexly fractured rocks. Such an approach has been commercialized in Golder Associates' FracMan Reservoir Edition software. For realistic reservoir simulations, however, it would be desirable if a third compressible gas phase can be included which is often present at reservoir conditions. Here we present the extension of an existing node-centred finite volume - finite element (FEFV) discretization for the efficient and accurate simulations of three-component - three-phase flow in geologically realistic representations of fractured porous media. Two possible types of fracture networks can be used: In 2D, they are detailed geometrical representations of fractured rock masses mapped in field studies. In 3D, they are geologically constrained, stochastically generated discrete fracture networks. Flow and transport can be simulated for fractures only or for fractures and matrix combined. The governing equations are solved decoupled using an implicit-pressure, explicit-saturation (IMPES) approach. Flux and concentration terms can be treated with higher-order accuracy in the finite volume scheme to preserve shock fronts. The method is locally mass conservative and works on unstructured, spatially refined grids. Flash calculations are carried out by a new description of the Black-Oil model. Capillary and gravity effects are included in this formulation. The robustness and accuracy of this formulation is shown in several applications. First, grid convergence is demonstrated for structured and unstructured finite element meshes. Then we use 2D discrete fracture models in more complex geometries to illustrate the effect of mesh quality. Finally, we show an application of the proposed method to the simulation of three-component - three-phase flow in a detailed 2D representation of fractured chalk mapped in the Bristol Channel, U.K and a 3D discrete fracture network.
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.
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede
2014-01-01
This paper investigates the active damping of LCL-filter resonance within single-loop grid current control of grid-connected voltage source converters. First, the basic analysis in the continuous s-domain reveals that the grid-current-feedback active damping forms a virtual impedance across the grid-side inductor, and the use of a high-pass filter with a negative sign shapes the virtual impedance by an RL damper paralleled by a negative inductance. It is further found that such a negative virtual inductance plays a critical role in mitigating the phase lag caused by the time delay in a digital control system. The instability induced by the negative virtual resistance, which is commonly experienced in the feedback-type active damping, can thus be avoided. A systematic design method of the highpass filter is also proposed by the help of root locus analysis in the discrete z-domain. Lastly, experimental tests are presented to validate the theoretical analysis.
Sudha Rani, G.; RASOOL AHEMMED.SK; Lavanya, N.
2013-01-01
This paper attempts to analyse the dominant harmonics present in sinusoidal PWM inverter output with AC source . A new technique for reducing this harmonics in PWM inverter output by modifying the reference waveform is proposed, by using MATLAB simulations.
Description of the three-phase contact line expansion
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Váchová Tereza
2014-03-01
Full Text Available Knowledge of bubble-particle interaction is important in many industrial processes such as in flotation. While the collision (first interaction sub-process between bubbles and particles is influenced only by hydrodynamic forces, the bubble behaviour during the attachment (second sub-process is influenced both by hydrodynamic and surface forces. This work is focused on the study of the three-phase contact (TPC line expansion during bubble adhesion on hydrophobic surface and on its experimental and mathematical description. The experiments were carried out in pure water where mobile bubble surface is expected. The rising bubble was studied in dynamic arrangement, whereas the stationary bubble was analysed in static arrangement. The attachment process was recorded using a high-speed digital camera and evaluated using image analysis. The diameter of the expanding TPC line as well as the dynamic contact angle was determined. Two approaches - the hydrodynamic and the molecular-kinetic - were used for mathematical description of the TPC line expansion. According to our results, the hydrodynamic model is suitable for the description of the initial fast phase of the expansion. The molecular-kinetic model was assessed as appropriate for almost whole range of TPC expansion. Parameters of the model were evaluated and compared for both types of arrangement.
Description of the three-phase contact line expansion
Váchová, Tereza; Brabcová, Zuzana; Basa?ová, Pavlína
2014-03-01
Knowledge of bubble-particle interaction is important in many industrial processes such as in flotation. While the collision (first interaction sub-process) between bubbles and particles is influenced only by hydrodynamic forces, the bubble behaviour during the attachment (second sub-process) is influenced both by hydrodynamic and surface forces. This work is focused on the study of the three-phase contact (TPC) line expansion during bubble adhesion on hydrophobic surface and on its experimental and mathematical description. The experiments were carried out in pure water where mobile bubble surface is expected. The rising bubble was studied in dynamic arrangement, whereas the stationary bubble was analysed in static arrangement. The attachment process was recorded using a high-speed digital camera and evaluated using image analysis. The diameter of the expanding TPC line as well as the dynamic contact angle was determined. Two approaches - the hydrodynamic and the molecular-kinetic - were used for mathematical description of the TPC line expansion. According to our results, the hydrodynamic model is suitable for the description of the initial fast phase of the expansion. The molecular-kinetic model was assessed as appropriate for almost whole range of TPC expansion. Parameters of the model were evaluated and compared for both types of arrangement.
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 m³ s-1 and the liquid phase flow (Q [...] L) varying in the range from 4.25x10-6 m³ s-1 to 0.50x10-6 m³ 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.
Mathematical modeling of a three-phase trickle bed reactor
Directory of Open Access Journals (Sweden)
J. D. Silva
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 m³ s-1 and the liquid phase flow (Q L varying in the range from 4.25x10-6 m³ s-1 to 0.50x10-6 m³ 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 Upward Flow in a Vertical Pipe
International Nuclear Information System (INIS)
Many specialized technologies need to be developed to deal with the mobilization, retrieval, transport and reliable delivery of large amounts of toxic and radioactive waste to pretreatment facilities. At these facilities the waste is prepared for long term, unsupervised storage. At Hanford as well as other DOE nuclear sites, there are many underground storage tanks that are holding many millions of gallons of toxic and radioactive waste. A class of these storage tanks can utilize pneumatic conveying for the retrieval of scarified solids that are occasionally laced with sticky sludge, followed by slurry transport to pretreatment facilities. The formation of a thin liquid film that travels upwards along the internal wall of a vertical retrieval pipe may prevent those particles that are laced with the sticky sludge from adhering to it and eventually causing instability and blockage. In this paper we develop an approach to the design of a three-phase gas-solid-liquid flow system that could transport scarified solid particles, including sticky particles, pneumatically through a vertical pipe. A liquid film is introduced and maintained along the pipe's inner wall to act as a lubricant that ensure that sticky particles will continue to be transported without permanently adhering to the pipe wall. The system's operating conditions are within the boundaries of the annular dispersed region on a typical flow pattern map of vertical flow of a gas-liquid mixture. High gas superficof a gas-liquid mixture. High gas superficial velocities combined with low liquid superficial velocities, conditions that satisfy the requirement and geometry of our proposed system, characterize such a region
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.
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.
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 Novel SVPWM Technology Used in PWM Rectifiers of WPGS
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Zhang Junli
2013-04-01
Full Text Available In order to achieve the transformation of electrical energy in Variable Speed Constant Frequency (VSCF Wind Power Generation System (WPGS, a novel Space Vector Pulse Width Modulation (SVPWM pulse trigger technology applied in high efficient PWM rectifier is proposed. Rectifier is an important part of WPGS and its performance affects the harmonic content and power factor of the power energy delivered to the grid. In order to improve the performance of PWM rectifier, a novel SVPWM pulse generator technology is proposed. Compared with other kinds of PWM pulse generator systems, Space Vector Pulse Width Modulation (SVPWM has many advantages such as clear physical concept, simple algorithm, suitable for digital implementation, high voltage utilization, low harmonic content, low switches losses and simple hardware circuit.
Neural network based PWM AC chopper fed induction motor drive
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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. .
Realise of PWM-generating based on FPGA
International Nuclear Information System (INIS)
The power supply digital controllers of Shanghai Synchrotron Radiation Facility(SSRF) make use of the PWM (pulse width modulation) wave as the feedback to the power-electrical devices, so as to obtain constant current of high accuracy and stability. The design of PWM wave generation structure in FPGA is good for a compact controller,and the reduction of the usage of Integrated Circuits (ICs) decreases the interference from the noise among the ICs, hence better performance of the controller. In addition, FPGA can be programmed circularly at any time,so as to optimize the structure design and make a maximum use of the advantage of FPGA. As a part of transplanting the complete function of the DSP (digital signal processor/processing), realizing the generation of PWM wave in FPGA is feasible. In this paper, we report progress in this regard at SSRF. (authors)
Research on a New Control Strategy of Three Phase Inverter for Unbalanced Loads
Directory of Open Access Journals (Sweden)
Chunxi LIU
2010-01-01
Full Text Available One of the very important functions of three-phase inverter is to maintain the symmetric three-phase output voltage when the three-phase loads are unbalanced. Although the traditional symmetrical component decomposing and superimpose theory can keep the voltage balance through compensating the positive-, negative- and zero-sequence components of the output voltage of inverter, however, this method is time-consuming and not suitable for control. Aiming at high power medium frequency inverter source, a P+Resonant (Proportion and Resonant controller which ensured a balanced three phase output voltage under unbalanced load is proposed in this paper. The regulator was proved to be applicable to both three-phase three-wire system and three-phase four-wire system and developed two methods of realization. The simulation results verified that this method can suppressed effectively the output voltage distorted caused by the unbalanced load and attained a high quality voltage waveforms.
Research on a New Control Strategy of Three Phase Inverter for Unbalanced Loads
Chunxi LIU; Weiming Ma; Hu, Wenhua
2010-01-01
One of the very important functions of three-phase inverter is to maintain the symmetric three-phase output voltage when the three-phase loads are unbalanced. Although the traditional symmetrical component decomposing and superimpose theory can keep the voltage balance through compensating the positive-, negative- and zero-sequence components of the output voltage of inverter, however, this method is time-consuming and not suitable for control. Aiming at high power medium frequency inverter s...
Tine L. Vandoorn; Jeroen D. M. De Kooning; Jan Van de Vyver; Lieven Vandevelde
2013-01-01
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 f...
Three-phase Magnitude-phase Detection Based on T/4 Time-lapse Elimination Method
Xiaoying Zhang; Zheng Jiang; Ning Ding
2014-01-01
Affected by the negative sequence component and harmonic component of three-phase grid, the conventional three-phase software phase-locked loop (SPLL) circuits were unable to extract the magnitude-phase information of three-phase fundamental positive sequence component accurately, and the dynamic response speed was slow. In order to solve this problem, this paper intro...
Inverter Output Filter Effect on PWM Motor Drives of a Flywheel Energy Storage System
Santiago, Walter
2004-01-01
NASA Glenn Research Center (GRC) has been involved in the research and development of high speed flywheel systems for small satellite energy storage and attitude control applications. One research and development area has been the minimization of the switching noise produced by the pulsed width modulated (PWM) inverter that drives the flywheel permanent magnet motor/generator (PM M/G). This noise can interfere with the flywheel M/G hardware and the system avionics hampering the full speed performance of the flywheel system. One way to attenuate the inverter switching noise is by placing an AC filter at the three phase output terminals of the inverter with the filter neutral point connected to the DC link (DC bus) midpoint capacitors. The main benefit of using an AC filter in this fashion is the significant reduction of the inverter s high dv/dt switching and its harmonics components. Additionally, common mode (CM) and differential mode (DM) voltages caused by the inverter s high dv/dt switching are also reduced. Several topologies of AC filters have been implemented and compared. One AC filter topology consists of a two-stage R-L-C low pass filter. The other topology consists of the same two-stage R-L-C low pass filter with a series connected trap filter (an inductor and capacitor connected in parallel). This paper presents the analysis, design and experimental results of these AC filter topologies and the comparison between the no filter case and conventional AC filter.
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.
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.
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.
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.
Simple PWM modulator topology with excellent dynamic behavior
DEFF Research Database (Denmark)
Poulsen, SØren; 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.
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, Electric al Engineering
PWM Rectifier in Comparison to Phase Contolled Rectifier.
Czech Academy of Sciences Publication Activity Database
Lettl, Ji?í
Brno : VUT FEKT Brno, 2008, s. 1-6. ISBN 978-80-7204-603-4. [EPVE 2008. Brno (CZ), 11.11.2008-12.11.2008] Institutional research plan: CEZ:AV0Z20570509 Keywords : PWM rectifier * electromagnetic compatibility * harmonic analysis Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
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
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…
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.
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 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
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
Instantaneous Power Compensation in Three-Phase Systems by Using p-q-r Theory
DEFF Research Database (Denmark)
Kim, Hyosung; Blaabjerg, Frede
2002-01-01
Three linearly independent instantaneous powers have been defined in the time domain in three-phase four-wire systems with the use of p-q-r theory. Any three-phase circuit can be transformed into three single-phase circuits by the p-q-r transformation Thus the instantaneous powers in any three-phase systems can be analysed as the same way of instantaneous power in single-phase systems.This paper analyses the instantaneous powers spectrally in the frequency domain for single-phase systems and three-phase systems. Each instantaneous power in three-phase systems has its own spectral pattern that is characterized by the spectral distribution of the system voltages and currents. The instantaneous power in single-phase systems has its own spectral pattern different from that of three-phase systems.From the spectral analysis of the instantaneous powers, powers are newly defined in the frequency domain. The definition of the powers is consistent through single-phase systems and three-phase systems and is well agreed with the traditional definition of powers in sinusoidal single-phase systems. Based on the defined powers, some useful power quality factors are defined to evaluate power qualities for various circuit conditions.
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 à rede alimentado por um conjunto fotovoltaico. O conversor é composto de um estágio CC-CC isolado um estágio CC-CA. São obtidas funções de transferência com as quais são projetados três sistemas de controle em malha f [...] echada: um para a tensão de entrada do arranjo de painéis solares, um para a tensão do do barramento de tensão 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.
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.
Novel, Four-Switch, Z-Source Three-Phase Inverter
Antal, Robert; Muntean, Nicolae; Boldea, Ion; Blaabjerg, Frede
2011-01-01
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 ...
PWM Technique to Overcome the Effect of High PAPR in Wireless Systems
Omar Daoud
2014-01-01
Many current communication systems suffer from perf ormance degradation due to the high sensitivity to high power peaks especially in the nonlinear device s. The author introduces a new concept based on the Pulse Width Modulation (PWM), namely MIMO-OFDM syst em based PWM (MO-PWM) to overcome this deficiency. Here, the peak-to-average power ratio ( PAPR) problem in Orthogonal Frequency Division Multiplexing (OFDM) technique is used as a criterio n to check the validi...
Controlling DC Motor using Microcontroller (PIC16F72) with PWM
Shruti Shrivastava, Jageshwar Rawat, Amit Agrawal
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...
Controlling DC Motor using Microcontroller (PIC16F72 with PWM
Directory of Open Access Journals (Sweden)
Shruti Shrivastava, Jageshwar Rawat, Amit Agrawal
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. Togenerate PWM signals we use PIC16F72 microcontroller.
Prediction of power losses in silicon iron sheets under PWM voltage supply
International Nuclear Information System (INIS)
The behavior of iron losses in silicon iron steels submitted to a PWM voltage is studied. The influence of modulation parameters (the depth of modulation and the number of eliminated harmonics) is clarified. In particular, the idea of an equivalent alternating pulse voltage that gives the same iron losses as the PWM voltage is established. An estimation formula for iron losses under the PWM voltage is developed based on the loss separation model and the voltage form factor. ((orig.))
Analysis and Design of a Higher Current ZVS-PWM Converter for Industrial Applications
Navid Golbon; Gerry Moschopoulos
2013-01-01
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...
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.
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.
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.
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.
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.
Apparent permeability of electrical steel under PWM magnetisation
International Nuclear Information System (INIS)
In recent years much attention has been paid to material performance under pulse width modulation (PWM) excitation conditions, which is of increasing importance to motor applications particularly in energy efficient variable speed drive systems. It is well known that in general, losses increase significantly with reducing modulation index, the increase depending on parameters such as silicon contents, thickness and grain size. The effect of the PWM waveform on permeability has attracted little attention until now. So in this paper its influence on the permeability of electrical steel is analysed and characterised. A prediction approach based on the permeability under sine wave excitation and total harmonic distortion is introduced which results in errors below 10% for non-electrical steel at 1.5 T
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.
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...
Fuzzy Logic Closed Loop Control of 5 level MLI Driven Three phase Induction motor
Mulukutla Venkata Subramanyam; Prasad, P. V. N.; Poornachandra Rao, G.
2013-01-01
This paper deals about fuzzy logic control of closed loop controlled five level Multi Level Inverter (MLI) driven three phase induction motor. Three phase Induction motor is most widely used drive in Industries, so needs proper control of speed. Induction motor is fed from five level multilevel inverter which is controlled by fuzzy logic. The closed loop consists of two loops. First inner loop is current loop and second outer loop is speed loop. The torque is varied at different times and cor...
Direct torque control for dual three-phase induction motor drives
Farina, Francesco; Profumo, Francesco; Griva, Giovanni Battista; Tenconi, Alberto; Bojoi, Iustin Radu
2005-01-01
A direct torque control (DTC) strategy for dual three-phase induction motor drives is discussed in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees. The DTC strategy is based on a predictive algorithm and is implemented in a synchronous reference frame aligned with the machine stator flux vector. The advantages of the discussed control strategy are constant inverter switching frequency, good transient and steady-state per...
POWER FACTOR IMPROVEMENT IN THREE PHASE AC-AC CONVERTER THROUGH MODIFIED SPWM
P.VASUKI,; Mahalakshmi, R.
2011-01-01
Recently, a new generation of ac-ac single-phase and three-phase power converters with more commutations per half cycle has been proposed for ac power due to the increasing availability and power capability of high frequency controlled-on and off power emiconductor switching devices. This paper presents three phase ac-acconverter whose control strategy is based on modified sinusoidal ulse-width modulation switching technique. As majority of the industrial loads are being inductive, the pow...
Three-phase Magnitude-phase Detection Based on T/4 Time-lapse Elimination Method
Directory of Open Access Journals (Sweden)
Xiaoying Zhang
2014-02-01
Full Text Available Affected by the negative sequence component and harmonic component of three-phase grid, the conventional three-phase software phase-locked loop (SPLL circuits were unable to extract the magnitude-phase information of three-phase fundamental positive sequence component accurately, and the dynamic response speed was slow. In order to solve this problem, this paper introduces T/4 time-lapse elimination detection, a novel method of detecting three-phase magnitude-phase based on double d-q synchronous reference frame, functioning in decoupling positive and negative sequences of fundamental wave. When the voltage (or current fundamental positive and negative sequence components are separated, the positive sequence component as well as the magnitude and phase position of negative sequence component from three-phase fundamental can be detected, so it is effective to restrain the impact on detection precision from negative sequence component. To verify the performance of this novel method, simulation experiments like transient response under normal grid condition, dynamic response under three-phase unbalance with harmonic pollution condition and dynamic response under phase jump condition are carried out. The simulation results verify that the proposed method overcomes the shortcoming of conventional three-phase phase-locked loop and tracks accurately the magnitudes and phases of the foundational positive-sequence voltage under harmonic pollution condition. And the results also verify that the proposed method can suppress odd harmonic propagation and has a higher detecting precision comparing with T/16 time-lapse elimination method. The improved T/4 time-lapse elimination detection can be wildly applied in three-phase power electronic devices.
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
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.
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)
Voltage Balancing in Diode Clamped Multilevel Inverter Using Sinusoidal PWM
Shalini, S.
2013-01-01
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...
Neural network based PWM AC chopper fed induction motor drive
Venkatesan Jamuna; Sathi Reddy Rama
2009-01-01
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 driv...
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
Single Phase Bidirectional PWM Converter for Microgrid System
Kalavalli, C.; Parkavikathirvelu, K.; 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 ...
CARRIER OVERLAPPING PWM METHODS FOR ASYMMETRICAL MULTILEVEL INVERTER
Seyezhai, Dr R.
2011-01-01
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 Pu...
HIGH EFFICIENCY BRIDGELESS PWM CUK CONVERTER WITH SOFT SWITCHING TECHNIQUE
ANJAN KUMAR SAHOO, SARIKA KALRA, NITIN SINGH
2013-01-01
High efficiency bridgeless single-phase ac-dc PWM cuk converter with soft-switching (ZVS) technique is proposed. This paper emphasizes more on the converter efficiency. The conduction losses and input current harmonics of the proposed converter is very less due to the absence of the input diode bridge and also during each switching cycle, only two semiconductor switches are present in the current path unlike other conventional Cuk converters. Soft switching (ZVS)technique is applied by using ...
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
The analysis of magnesium oxide hydration in three-phase reaction system
International Nuclear Information System (INIS)
In order to investigate the magnesium oxide hydration process in gas–liquid–solid (three-phase) reaction system, magnesium hydroxide was prepared by magnesium oxide hydration in liquid–solid (two-phase) and three-phase reaction systems. A semi-empirical model and the classical shrinking core model were used to fit the experimental data. The fitting result shows that both models describe well the hydration process of three-phase system, while only the semi-empirical model right for the hydration process of two-phase system. The characterization of the hydration product using X-Ray diffraction (XRD) and scanning electron microscope (SEM) was performed. The XRD and SEM show hydration process in the two-phase system follows common dissolution/precipitation mechanism. While in the three-phase system, the hydration process undergo MgO dissolution, Mg(OH)2 precipitation, Mg(OH)2 peeling off from MgO particle and leaving behind fresh MgO surface. - Graphical abstract: There was existence of a peeling-off process in the gas–liquid–solid (three-phase) MgO hydration system. - Highlights: • Magnesium oxide hydration in gas–liquid–solid system was investigated. • The experimental data in three-phase system could be fitted well by two models. • The morphology analysis suggested that there was existence of a peel-off process
Design and Implementation of carrier based Sinusoidal PWM Inverter
Directory of Open Access Journals (Sweden)
PANKAJ H ZOPE
2013-04-01
Full Text Available SPWM or sinusoidal pulse width modulation is widely used in power electronics to digitize the power so that a sequence of voltage pulses can be generated by the on and off of the power switches. The pulse width modulation inverter has been the main choice in power electronic for decades, because of its circuit simplicity and rugged control scheme SPWM switching technique is commonly used in industrial applications SPWM techniques are characterized by constant amplitude pulses with different duty cycle for each period. The width of this pulses are modulated to obtain inverter output voltage control and to reduce its harmonic content. Sinusoidal pulse width modulation or SPWM is the mostly used method in motor control and inverter application. In this development a unipolar and bipolar SPWM voltage modulation type is selected because this method offers the advantage of effectively doubling the switching frequency of the inverter voltage, thus making the output filter smaller, cheaper and easier to implement. Conventionally, to generate this signal, triangle wave as a carrier signal is compared with the sinusoidal wave, whose frequency is the desired frequency. In this paper single-phase inverters and their operating principles are analyzed in detail. The concept of Pulse Width Modulation (PWM for inverters is described with analyses extended to different kinds of PWM strategies. Finally the simulation results for a single-phase inverter (unipolar using the PWM strategies described are presented [1],[2],[3].
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.
Development of a PWM precision spraying controller for unmanned aerial vehicles
This paper presents a new pulse width modulation (PWM) controller for unmanned aerial vehicle (UAV) precision sprayer for agriculture using a TL494 fix-frequency pulse width modulator together with a data acquisition board and developed software. The PWM controller was implemented through the guidan...
Directory of Open Access Journals (Sweden)
G.SUDHA RANI
2013-04-01
Full Text Available This paper attempts to analyse the dominant harmonics present in sinusoidal PWM inverter output with AC source . A new technique for reducing this harmonics in PWM inverter output by modifying the reference waveform is proposed, by using MATLAB simulations.
PID Controller Design for UPS Three-Phase Inverters Considering Magnetic Coupling
Directory of Open Access Journals (Sweden)
Yu Zhang
2014-11-01
Full Text Available In three-phase inverters used in uninterruptible power supplies (UPSs, three-limb inductors and three-limb transformers are commonly used in consideration of cost and size. However, magnetic coupling exists between the three phases of the inverter, which can result in complex models. When instantaneous feedback control strategies are introduced to achieve high quality output waveforms, the transient analysis of the closed-loop inverters becomes difficult. In this paper, the phenomenon of magnetic coupling in three-phase inverters due to three-limb inductors and three-limb transformers is analyzed. A decoupled dynamic model is derived based on the instantaneous symmetrical components transformation, which comprises three decoupled equivalent circuits of instantaneous symmetrical components. Analyses based on this model indicate that magnetic coupling may have a significant impact on the performance of three-phase inverters under unbalanced load conditions and transient responses. For three-phase inverters in UPSs with Proportional-Integral-Differential (PID closed-loop control strategies, the interactive influence between instantaneous closed-loop regulation and magnetic coupling is researched. Finally, a method of reliability analysis and PID controller design for inverters with magnetic coupling is derived. Simulation and experiment results validate the model and conclusions.
International Nuclear Information System (INIS)
Objective: To investigate the difference between the early phases and delay phase of three-phase bone scintigraphy on hemiplegic patients with earlier complex regional pain syndrome (CRPS). Methods: Twenty-nine stroke patients with hemiplegia complicating CRPS received three-phase bone scintigraphy after intravenous injection of 99Tcm-methylene diphosphonate (MDP). The region of interest (ROI) technique was used to obtain the radioactive counts of involved joints and contralateral sites on wrists, metacarpophalangeal, proximal interphalangeal and distal interphalangeal joints. The total counts of these four sites in each patient were then obtained and the total uptake ratios of involved joints/contralateral joints for each phase were calculated to compare the difference among the three phases. Wilcoxon test and ANOVA were used in data analyses. Results: The involved joints of hemiplegic side displayed higher tracer uptake. There were significant differences of the radioactive counts between involved joints and uninvolved ones in the perfusion, pool and delay phase (Wilcoxon test, Z: -4.73 to -2.10, P<0.05). There was no significant difference of total uptake ratios of involved joints/contralateral joints among the three phases (ANOVA, F = 0. 807, P < 0.05). Conclusions: Due to higher bone seeking agent accumulation on three-phase bone scintigraphy, both early phases and delay phase imaging showed similar value in stroke patients with hemiplegia complicating earlier CRPS. (authors)
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.
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.
DEFF Research Database (Denmark)
Xiao, Lei; Huang, Shoudao
2013-01-01
Unbalanced grid voltage will cause large dc-bus voltage ripple and introduce high harmonic current components on the grid side. This will severely threaten the safety of the grid-connected voltage source converter (VSC) and consequently, affect the healthy operation condition of the load. In this study, a new proportional-integral-resonant (PI-RES) controller-based, space vector modulated direct power control topology is proposed to suppress the dc-bus voltage ripple and in the same time, controlling effectively the instantaneous power of the VSC. A special ac reactive power reference component is introduced in the controller, which is necessary in order to reduce the dc-bus voltage ripple and active power harmonics at the same time. The proposed control topology is implemented in the lab. Simulation and experimental results are provided to validate its performance and the analysis presented in this study.
Piyarat, Wekin; Kinnares, Vijit
This paper presents a performance evaluation and a simple speed control method of an asymmetrical parameter type two-phase induction motor drive using a three-leg VSI (Voltage Source Inverter). The two-phase induction motor is adapted from an existing single-phase induction motor resulting in impedance unbalance between main and auxiliary windings. The unbalanced two-phase inverter outputs with orthogonal displacement based on a SPWM (Sinusoidal Pulse Width Modulation) method are controlled with appropriate amplitudes for improving the motor performance. Dynamic simulation of the proposed drive system is given. A simple speed controller based on a slip regulation method is designed. The overall system is implemented on a DSP (Digital Signal Processor) board. The validity of the proposed system is verified by simulation and experimental results.
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.
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.
Fast asymmetrical three-phase load flow based on symmetrical component
International Nuclear Information System (INIS)
This paper deals with the three-phase asymmetrical load-flow problem. It presents a solution of this problem in the sequence domain, which is more efficient than standard solutions in both the phase and the sequence domain. It specially copes with asymmetrical states of unbalanced power systems. The efficiency is achieved by introducing the following basic advancements of the standard asymmetrical load-flow calculations: 1 - Elimination of phase-shifts from the sequence circuits of three-phase transformers; 2 - Enhancement of the standard classification of power systems buses to provide a correct treatment of Q limits enforcement; 3 - Synthesizing of buses of the generators and step-up transformers in the transformers high voltage buses; thus, reducing the form of the three-phase asymmetrical load-flow models to the form of symmetrical models. The efficiency of the presented solution in memory, CPU time and robustness is confirmed on the basis of several examples. (Original)
A Novel Unit Power Factor Rectifier Based on Three-phase Digital PLL
Directory of Open Access Journals (Sweden)
Xuegui Zhu
2013-07-01
Full Text Available A novel three-phase phase-locked loop solution is proposed based on D-Q transformation aiming at the AC-DC rectifier with high efficiency and high power factor. The phase-locked loop is implemented digitally using the Xilinx blockset integrated with Matlab/Simulink. The three-phase digital phase-locked loop (TDPLL is elaborately designed with the parameters defined in detail. The AC-DC converter (rectifier model with the TDPLL is built and simulated in the high-speed VHS-ADC simulation platform from Canada. The simulation and test results show the TDPLL is locked right after the different three-phase voltage disturbances and very suitable for control of the rectifier with high parallelism through space vector pulse width modulation (SVPWM.
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.
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.
Uncertainty Assessment of Interpolation-Based Three Phase Relative Permeability Models
Ranaee, Ehsan; Giovanni, Porta; Monica, Riva; Alberto, Guadagnini
2013-04-01
A major element affecting uncertainty associated with prediction of three-phase flow in reservoirs is the parameterization of relative permeability. The latter are typically obtained through interpolation of two phase relative permeability data because of intrinsic difficulties related to direct measurements. Here, we discuss and analyze the saturation history dependency of water, oil and gas relative permeabilities and distinguish key features of three- and two- phase flow configurations. We start by investigating the advantages and limitations of several methodologies available in the literature and widely adopted in three-phase flow simulation. This analysis is performed by comparing model outcomes against experimental data published in the literature. The results provided by considering Corey-type equations as input to the aforesaid models is compared against the use of linear interpolation of two-phase measurements from oil-water and oil-gas environment. Our results show that available models typically fail to reproduce the set of experimental results ever the full range of saturations. This analysis suggests that not only saturation history but also wettability, residual oil and trapping behavior of oil during drainage and imbibition are key elements distinguishing between the physics of two- and three-phase settings. These effects should be taken in account to predict three-phase relative permeability. We then propose an alternative formulation to compute oil relative permability under three-phase conditions. Our model takes into account (i) the dependence of three-phase oil relative permeability on the saturation path, and (ii) the effect of wettability observed for three-phase systems. The model is based on a sigmoid-type interpolation of the oil relative permeability-saturation data in a two-phase oil-water system. Three-phase oil relative permeability is then computed through an additional interpolation between the oil-water effective sigmoid curve and the oil-gas two-phase data. Model results are compared with experimental data for secondary water injection and primary gas injection. Sensitivity of the model outcome to the sigmoid interpolation parameters is considered through an uncertainty quantification study. Keywords: oil relative permeability, WAG, cycle dependency, trapped oil.
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...
Field results on developed three-phase four-wire shunt active power filters
Pinto, J. G.; Neves, Pedro; Gonçalves, Domingos; João 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...
Fuzzy Logic Closed Loop Control of 5 level MLI Driven Three phase Induction motor
Directory of Open Access Journals (Sweden)
Mulukutla Venkata Subramanyam
2013-02-01
Full Text Available This paper deals about fuzzy logic control of closed loop controlled five level Multi Level Inverter (MLI driven three phase induction motor. Three phase Induction motor is most widely used drive in Industries, so needs proper control of speed. Induction motor is fed from five level multilevel inverter which is controlled by fuzzy logic. The closed loop consists of two loops. First inner loop is current loop and second outer loop is speed loop. The torque is varied at different times and corresponding change in speed and Total Harmonic Distortion (THD is observed. The MLI is controlled by Sinusoidal Pulse Width Modulation (SPWM Technique
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.
TORQUE ANALYSIS OF THREE-PHASE INDUCTION MOTOR UNDER VOLTAGE UNBALANCE USING 2D FEM
Directory of Open Access Journals (Sweden)
ALI EBADI,
2011-02-01
Full Text Available Because of various techno-economic benefits, three-phase induction motors are used extensively in industry, commercial and residential applications and most of them are connected to electric power distribution system directly, thus they will be affected by voltage quality problems. An important voltage quality problem in power systems is voltage unbalance. Therefore, it is very important to studyperformance of these motors under unbalanced voltages. In this paper, Two-Dimensional Finite Element Method is employed to analyze the performance of a three-phase squirrel cage induction motor undervoltage unbalance, focusing on electromagnetic torque.
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.
Kerner, B S; Brakemeier, A
2007-01-01
A testbed for wireless vehicle communication based on a microscopic model in the framework of three-phase traffic theory is presented. In this testbed, vehicle motion in traffic flow and analyses of a vehicle communication channel access based on IEEE 802.11e mechanisms, radio propagation modeling, message reception characteristics as well as all other effects associated with ad-hoc networks are integrated into a three-phase traffic flow model. Based on simulations of this testbed, some statistical features of ad-hoc vehicle networks as well as the effect of C2C communication on increase in the efficiency and safety of traffic are studied.
THD Analysis of Cascaded Mli for Various PWM Techniques
Directory of Open Access Journals (Sweden)
K.L.Dheeraj
2014-05-01
Full Text Available Cascaded inverters are ideal for connecting renewable energy sources with an AC grid, because of the need for separate dc sources, which is the case in applications such as photo voltaics or fuel cells. The inverter could be controlled to either regulate the power factor of the current drawn from the source or the bus voltage of the electrical system where the inverter was connected. The modulation techniques are crucial in operating any inverter at desired conditions. In this paper different pwm techniques are implemented for three level and five level cascaded mli and THD variation is analysed with variation of modulation index.
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...
Pengaruh Penambahan PWM (Pulse Width Modulation Pada Generator HHO Tipe Dry Cell
Directory of Open Access Journals (Sweden)
Fungky Dyan Pertiwi
2013-09-01
Full Text Available Generator HHO memanfaatkan proses elektrolisis air agar mendapatkan gas H2. Namun, pada praktiknya pemakaian arus dari aki yang besar dan temperatur tinggi membuat bejana generator menjadi cepat rusak, sehingga dibutuhkan tambahan rangkaian elektronika PWM pada pengujian generator HHO guna mengatasi permasalahan tersebut. Penelitian menggunakan elektroda plat berjumlah 9 berdimensi 120mm 120mm, tebal 1mm dan dibatasi oleh o-ring dengan diameter 126mm, tebal 3mm. Pengujian dilakukan secara eksperimen dengan 2 kelompok yaitu kelompok control yang mana pengujian tanpa menggunakan PWM serta kelompok uji dimana pengujian menggunakan PWM dengan variasi duty cycle 30%, 50% dan 70%. Pengujian dilakukan hingga temperatur elektrolit 93oC. Hasil uji didapatkan bahwa arus, laju produksi dan efisiensi terbesar didapatkan pada pengujian tanpa PWM yang mencapai 60,6A, 6,033 10-6kg/s dan 25,69%. Namun, pada pengambilan data kedua efisiensi turun menjadi 19,74%. Penambahan PWM pada pengujian berpengaruh pada arus dan temperatur yang stabil meskipun laju produksi dan efisiensi lebih kecil daripada pengujian tanpa PWM. Pengujian dengan PWM pada duty cycle 70% menghasilkan laju produksi dan efisiensi terbesar yang mencapai 1,843 10-6 kg/s dan 15,19%.
Three-phase scintigraphy in epicondylitis of the lateral lower humerus
International Nuclear Information System (INIS)
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. (orig.)
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.
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.
Analysis of a Three Phase Induction Motor Directly from Maxwell's Equations
Bhattacharjee, Shayak
2011-01-01
The torque developed in a three phase AC squirrel cage motor is usually expressed in terms of resistances and reactances of the stator, the rotor, and the motor as a whole. We use Maxwell's equations to find the torque in terms of geometrical parameters. This allows us to estimate the torque developed by a motor without knowing the details of its circuitry.
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…
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.
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.
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
Analysis of Dc/Dc converters with PWM and sliding mode controls
International Nuclear Information System (INIS)
Static and dynamic performances of D C/D C converters with PWM and sliding mode controllers are investigated. To improve the performance of the PWM controller, a linear compensator is proposed and used. For sliding controller, important parameters such as sliding coefficients and filter time constant are carefully computed and used. Finally, a D C/D C buck converter with PWM and sliding controller is designed, modeled and constructed. Theoretical and experimental results are compared and the distinguished features and limitations of each control technique are presented
A new PWM based control method for forced commutated cycloconverters
International Nuclear Information System (INIS)
Highlights: ? A new control method is proposed for three-phase to single-phase cycloconverters from balanced and unbalanced input voltages. ? The proposed method has no limitation on frequency conversion and is independent of the load. ? In proposed method, the low order harmonics are not generated in the input and output quantities. ? The proposed method can be easily extended to three-phase to n-phase cycloconverters. ? We demonstrate real experimental results of the power converter. - Abstract: In this paper, a new control method is proposed for three-phase to single-phase cycloconverters for synthesizing the desired output voltage from balanced and unbalanced input voltages. The theoretical analysis of the proposed control method is given for both of the conventional topologies of three-phase to single-phase cycloconverters. Using the proposed control method, the maximum output/input voltage transfer ratios are 0.5 and 1.5 for conventional cycloconverters that consist of three and six bidirectional switches, respectively. The proposed control method has no limitation on frequency conversion and is independent of the load. In other words, using the proposed control method, the three-phase to single-phase cycloconverter can operate as a generalized transformer. Using the proposed control method, the low order harmonics are not generated in the input and output quantities. As a result, the size of the required filters is decreased. The proposed control metheased. The proposed control method can be easily extended to three-phase to n-phase cycloconverters based on the same principle of the operation. The simulation and experimental results verify the operation and performance of the proposed control method.
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 ...
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.
An algorithm for estimating fault location in an unbalanced three-phase power system
Energy Technology Data Exchange (ETDEWEB)
Soliman, S.A. [University of Qatar, Doha (Qatar). Electrical Engineering Department; Abdel-Rahman, M.H. [University of Mansoura (Egypt). Electrical Engineering Department; Al-Attar, E.; El-Hawary, M.E. [SNC/Lavalin, Halifax, Nova Scotia (Canada)
2002-10-01
A new algorithm for estimating fault location on a transmission line, as well as the fault type, is studied and tested using simulation data obtained from the Electromagnetic Transient Program (EMTP). The proposed algorithm is based on the least absolute value estimation approach (LAV), and uses digitized samples of post-fault voltage and current waveforms at the relay locations. The proposed algorithm is applied to two different model of the transmission line. The first model is a three phase long transmission line, while the second model is a three phase three terminals transmission line. The measurements taken at the relay location do not need to be synchronized. Effects of critical parameters on the behavior of the proposed algorithm and on the estimated fault location are examined. A computational comparison between the proposed algorithm and the least errors square (LES) is presented in the paper. (author)
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.
Dynamic D-Q Axis Modeling Of Three-Phase Asynchronous Machine Using Matlab
Directory of Open Access Journals (Sweden)
SHAKUNTLA BOORA, S.K AGARWAL, K.S SANDHU
2013-08-01
Full Text Available Abstract:This paper presents a dynamic d-q axis model of three- phase asynchronous motor in synchronously rotating frame. The systems of differential equations representing the dynamic state behaviours of the machine as developed are implemented in MATLAB/SIMULINK. The effects of the stepped sequence of mechanical loading on the motor output variables namely: three-phase stator currents (ia, ib and ic, electromechanical torque and rotor speed, d-q stator and rotor currents (iqs, ids, iqr and idr, d-q voltages (vqs and vds are examined. The results obtained clearly show the elegance of the d-q axis transformation theory in machine modelling and the inherent limitations of the direct-on-line starting of 3-hp and 2250-hp asynchronous motors.
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.
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.
A New Soft-Switched Three-Phase Four-Wire Shunt Active Power Filter
Directory of Open Access Journals (Sweden)
Mohammad Reza Moradian
2010-07-01
Full Text Available This paper presents a new soft switched topology for losses reduction in a three-phase four-wire shunt active power filter (SAPF. The soft-switching technique not only offers a reduction in switching loss and thermal requirement, but also allows the possibility of high frequency and snubberless operation. Improved circuit performance and efficiency as well as reduction of EMI emission can be achieved. The resonant dc link inverter with low voltage stress is used for power converter of a three-phase four-wire shunt active power filter. It is assumed that the active power filter is connected to a load that can be unbalanced and may also draw harmonic currents. The p-q theory is used for controlling the SAPF. The proposed topology and operation principle of the control method is discussed in detail, finally the feasibility of such a scheme is demonstrated through simulation studies.
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
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.
Toppo, Shilpa
Voltage stability studies (VSS) of the electric network is a crucial factor to make the system operate in stable region and to prevent power blackouts. There are several commercial tools available for VSS of electric transmission systems (TS) but not many for distribution systems (DS). With increasing penetration of distributed renewable generations and meshed network within DS, shipboard power system (SPS) and microgrid, these VSS tools need to be extended for DS. Due to inherent characteristic like high R/X ratio, three phase and unbalanced operation, DS or SPS requires different mathematical approach than TS. Unbalanced three phase power flow and continuation power flow tools were developed using current injection and corrector predictor methods in this work for VSS. Maximum loading point for given DS or SPS can be computed using developed tools to guide required preventive and corrective actions. Developed tool was tested and validated for several different test cases.
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., Wärnå; 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.
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)
Adaptive RBF Neural Network Control for Three-Phase Active Power Filter
Directory of Open Access Journals (Sweden)
Juntao Fei
2013-05-01
Full Text Available An adaptive radial basis function (RBF neural network control system for three?phase active power filter (APF is proposed to eliminate harmonics. Compensation current is generated to track command current so as to eliminate the harmonic current of non?linear load and improve the quality of the power system. The asymptotical stability of the APF system can be guaranteed with the proposed adaptive neural network strategy. The parameters of the neural network can be adaptively updated to achieve the desired tracking task. The simulation results demonstrate good performance, for example showing small current tracking error, reduced total harmonic distortion (THD, improved accuracy and strong robustness in the presence of parameters variation and nonlinear load. It is shown that the adaptive RBF neural network control system for three?phase APF gives better control than hysteresis control.
Optimisation of an asymmetric three phase-shift distributed feedback semiconductor laser
Fernandes, C. A. F.; Morgado, J. A. P.; Boavida, J. B. M.
2009-01-01
Abstract This paper shows that accurately optimised asymmetric three phase-shift (3PS)-distributed feedback (DFB) laser structures can strongly improve the stability of the single-longitudinal mode (SLM) operation, described by the mode selectivity and the flatness of the photon density profile, through an extended range of current injection, when compared to optimised symmetric 3PS-DFB structures reported elsewhere. This study reveals its importance in modern high bit-rate opti...
A parametric study on unbalanced three phase islanded microgrids with inverter interfaced units
Sanseverino, Eleonora Riva; Quang, Ninh Nguyen; Zizzo, Gaetano; Di Silvestre, Maria Luisa; Guerrero, Josep M.
2013-01-01
In this paper, the solution of the power flow for unbalanced three phase microgrids systems is proposed. The study aims at the integration of inverter interfaced units using the control law used for primary voltage and frequency regulation, so as to take into account possible small variations of these parameters to account for sudden load changes. The proposed study deals with unbalanced systems which is the typical case of small distribution systems and shows how the power losses term varies...
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.
Transient analysis of three-phase induction machine using different reference frames
Vivek Pahwa; Sandhu, K. S.
2009-01-01
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 a...
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...
Aslan Sabahaldeen Jalal Abdi
2011-01-01
The objective of this work is to investigate the performance of a conventional three phase induction motor supplied by unbalanced voltages. An effort to study the motor steady state performance under this disturbance is introduced. Using per phase equivalent circuit analysis with the concept of symmetrical components approach, the steady state performance is theoretically calculated. Also, a model for the induction motor with the MATLAB/Simulink SPS tools has been implemented and steady state...
Analysis of three-phase rectifiers with constant-voltage loads
Caliskan, Vahe; Perreault, David J.; Kassakian, John G.; Jahns, Thomas M.
2003-01-01
This work presents a quantitative analysis of the operating characteristics of three-phase diode bridge rectifiers with AC-side reactance and constant-voltage loads. We focus on the case where the AC-side currents vary continuously (continuous AC-side conduction mode). This operating mode is of particular importance in alternators and generators, for example. Simple approximate expressions are derived for the line and output current characteristics as well as the input power factor. Expressio...
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...
Chaotic Recurrence Analysis of Oil-Gas-Water Three-phase Flow in Vertical Upward Pipe
Ling-Fu Kong; Na Xie; Ying-Wei Li
2011-01-01
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 s...
Harmonic Wave Analysis and Suppression Research on Three-phase SPWM Inverter
Qiang Chen; Heping Liu; Hongbing Li; Hui Xie
2013-01-01
The output voltage of the Sinusoidal Pulse Width Modulation (SPWM) inverter contains various ultra harmonics. It increases the system’s power consumption and generates the harmonic interference. By establishing the mathematical model of the three-phase inverter and doing the FFT transformation on the output voltage, it analyses the relation between the output voltage and the combined conduction states of the inverter’s switches during one waveform cycle, it also analyzes the main pa...
Design of Nine Level Inverter Topology for Three Phase Induction Motor Drives
Sudhakar, G.; Prabhakaran, S
2014-01-01
A new approach of nine levels cascaded H-bridge multilevel inverter is proposed for three phase induction motor drives. Multilevel inverter is used synthesize a nearby sinusoidal voltage from various levels of dc voltages and the proposed cascade H bridge inverter is used to reduce the number of switches. The proposed nine level cascaded H-bridge multilevel inverters require less number of components to obtain same number of voltage levels when compared to diode clamped and flying capacitor t...
Three phase four wire shunt active power filter from theory to industrial facility tests
Exposto, Bruno; Gonçalves, Henrique; Pinto, J. G.; João 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...
Slip Compensation in Efficiency-Optimized Three-Phase Induction Motor Drive Systems
Assbeihat, Jamal M.; 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...
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...
Comparative Analysis of Three Topologies of Three-Phase Five Level Inverter
H S Sangolkar, P. A. Salodkar
2014-01-01
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 sinu...
Design of Three Phase Matrix Converter AC-AC Utility Power Supply using SPWM Technique
Directory of Open Access Journals (Sweden)
Sagar. S. Pawar
2015-04-01
Full Text Available This paper describes the control analysis and design of an three phase matrix AC-AC utility power supply .The SPWM modulation techniques is used to control the desired output voltage and gives the control output voltage and reduced input harmonic distortions .In this Matrix converter Input is directly connected to output no DC link components is required. Simulation had been done using mat lab simulink and Simulated results are observed
Comparative Study of Controller Design for Four Quadrant Operation of Three Phase BLDC Motor
Suganya, Ms K.
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...
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...
TORQUE ANALYSIS OF THREE-PHASE INDUCTION MOTOR UNDER VOLTAGE UNBALANCE USING 2D FEM
ALI EBADI,; MOHAMMAD MIRZAIE,; SAYYED ASGHAR GHOLAMIAN
2011-01-01
Because of various techno-economic benefits, three-phase induction motors are used extensively in industry, commercial and residential applications and most of them are connected to electric power distribution system directly, thus they will be affected by voltage quality problems. An important voltage quality problem in power systems is voltage unbalance. Therefore, it is very important to studyperformance of these motors under unbalanced voltages. In this paper, Two-Dimensional Finite Eleme...
A New Topology of Three-Phase Four-Wire UPQC with a Simplified Control Algorithm
Yash Pal; Swarup, A.; Singh, B.
2012-01-01
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...
Adaptive Control for ZVS Three Phase Full Active Bridge Converter with ARCN
Molina Garcia, Jose Maria; García Suárez, Oscar; Asensi Orosa, Rafael; Alou Cervera, Pedro; Oliver Ramírez, Jesús Angel; Cobos Márquez, José Antonio
2012-01-01
This paper presents an adaptive control for the auxiliary circuit, called ARCN (Auxiliary Resonant Commutating Network), used to achieve ZVS in full active bridge converters under a wide load range. Depending on the load conditions, the proposed control adapts the timing of the ARCN to minimize the losses. The principle of operation and implementation considerations are presented for a three phase full active bridge converter, proposing different methods to implement the control according to ...
Adaptive RBF Neural Network Control for Three-Phase Active Power Filter
Juntao Fei; Zhe Wang
2013-01-01
An adaptive radial basis function (RBF) neural network control system for three?phase active power filter (APF) is proposed to eliminate harmonics. Compensation current is generated to track command current so as to eliminate the harmonic current of non?linear load and improve the quality of the power system. The asymptotical stability of the APF system can be guaranteed with the proposed adaptive neural network strategy. The parameters of the neural network can be adaptively updated to a...
Electrical Discharge Machining Flyback Converter using UC3842 Current Mode PWM Controller
Directory of Open Access Journals (Sweden)
Nazriah Mahmud
2014-10-01
Full Text Available This paper presents a current mode Pulse Width Modulation (PWM controlled Flyback converter using UC3842 for Electrical Discharge Machining current generator control circuit. Circuit simplicity and high efficiency can be achieved by a Flyback converter with current mode PWM controller. The behaviors of the system's operation is analyzed and discussed by varying the load resistance. Matlab sofware is used to simulate the Flyback converter where a prototype has been built and tested to verify it's performance.
Soft Switching Full-Bridge PWM DC/DC Converter Using Secondary Snubber
Jaroslav Dudrik; Vladimír Ruš?in; Marcel Bodor; Daniel Nistor Trip; Pavol Špánik
2009-01-01
A novel full-bridge PWM DC/DCconverter with controlled secondary side rectifier usingsecondary snubber is presented in this paper.Limitation of the circulating current as well as softswitching for all power switches of the inverter isachieved for full load range from no-load to shortcircuit by using controlled rectifier and snubber on thesecondary side. Phase shift PWM control strategy isused for the converter. The principle of operation isexplained and analyzed and the experimental resultson...
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; Camargo, Robinson F.; 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 tensões senoidais através de modulação por largura de pulso (PWM) digital. O propósito desta metodologia é o de determinar os parâmetros do filtro que assegure a especificação da máxima taxa de distorção harmônica total (THD) admissível nas tensões de saída do inversor PWM, para cargas lineares e não-lineares. A metodologia proposta é discutida ...
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
International Nuclear Information System (INIS)
The minimum and maximum excitation capacitance required for a self excited single phase induction generator using a three phase machine has been determined by an eigenvalue and eigenvalue sensitivity approach. It is observed that the required minimum capacitance reduces with the increase in load. Traditionally, the minimum and maximum capacitances required for a self excited induction generator (SEIG) were solved by a high order non-linear polynomial equation based on a per phase equivalent circuit model. The advantage of this proposed method is its simplicity since the complicated solution procedure of the high order polynomial is avoided. The generator consists of a three phase star connected induction machine with three capacitors connected in series and parallel with a single phase load. The developed dynamic model of the SEIG is based on the stationary reference frame d-q axes theory, and the equations of the excitation capacitors are described by a three phase abc model assuming a constant speed prime mover. The capacitance values obtained by the proposed method have been compared with those obtained by the conventional method and verified experimentally to confirm the validity and the accuracy of the proposed method
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.
Nucleation of the CO2 hydrate from three-phase contact lines.
Bai, Dongsheng; Chen, Guangjin; Zhang, Xianren; Wang, Wenchuan
2012-05-22
Using molecular dynamics simulations on the microsecond time scale, we investigate the nucleation and growth mechanisms of CO(2) hydrates in a water/CO(2)/silica three-phase system. Our simulation results indicate that the CO(2) hydrate nucleates near the three-phase contact line rather than at the two-phase interfaces and then grows along the contact line to form an amorphous crystal. In the nucleation stage, the hydroxylated silica surface can be understand as a stabilizer to prolong the lifetime of adsorbed hydrate cages that interact with the silica surface by hydrogen bonding, and the adsorbed cages behave as the nucleation sites for the formation of an amorphous CO(2) hydrate. After nucleation, the nucleus grows along the three-phase contact line and prefers to develop toward the CO(2) phase as a result of the hydrophilic nature of the modified solid surface and the easy availability of CO(2) molecules. During the growth process, the population of sI cages in the formed amorphous crystal is found to increase much faster than that of sII cages, being in agreement with the fact that only the sI hydrate can be formed in nature for CO(2) molecules. PMID:22551251
Detection of stator winding faults in induction motors using three-phase current monitoring.
Sharifi, Rasool; Ebrahimi, Mohammad
2011-01-01
The objective of this paper is to propose a new method for the detection of inter-turn short circuits in the stator windings of induction motors. In the previous reported methods, the supply voltage unbalance was the major difficulty, and this was solved mostly based on the sequence component impedance or current which are difficult to implement. Some other methods essentially are included in the offline methods. The proposed method is based on the motor current signature analysis and utilizes three phase current spectra to overcome the mentioned problem. Simulation results indicate that under healthy conditions, the rotor slot harmonics have the same magnitude in three phase currents, while under even 1 turn (0.3%) short circuit condition they differ from each other. Although the magnitude of these harmonics depends on the level of unbalanced voltage, they have the same magnitude in three phases in these conditions. Experiments performed under various load, fault, and supply voltage conditions validate the simulation results and demonstrate the effectiveness of the proposed technique. It is shown that the detection of resistive slight short circuits, without sensitivity to supply voltage unbalance is possible. PMID:21074767
Voltage Balancing in Diode Clamped Multilevel Inverter Using Sinusoidal PWM
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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.
Single Phase Bidirectional PWM Converter for Microgrid System
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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
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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.
HIGH EFFICIENCY BRIDGELESS PWM CUK CONVERTER WITH SOFT SWITCHING TECHNIQUE
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ANJAN KUMAR SAHOO, SARIKA KALRA, NITIN SINGH
2013-06-01
Full Text Available High efficiency bridgeless single-phase ac-dc PWM cuk converter with soft-switching (ZVS technique is proposed. This paper emphasizes more on the converter efficiency. The conduction losses and input current harmonics of the proposed converter is very less due to the absence of the input diode bridge and also during each switching cycle, only two semiconductor switches are present in the current path unlike other conventional Cuk converters. Soft switching (ZVStechnique is applied by using an auxiliary circuit to improve the efficiency of the proposed converter. Output voltage regulating control technique is provided to regulate the output which also ultimately improves the efficiency. Power factor is almost unity due to less input current harmonics. The circuit configuration, principle of operation, design procedure and simulation results are presented.
Nodular hepatocellular carcinoma : contrast enhancement patterns on three - phase spiral CT
International Nuclear Information System (INIS)
To evaluate contrast enhancement patterns of nodular hepatocellular carcinomas (HCCs) on three-phase spiral CT. A retrospective analysis of contrast enhancement patterns was performed in 48 patients with HCC. Three-phase dynamic CT images of hepatic arterial dominant phase, portal dominant phase, and delayed phase were obtained at 30, 65 and 360 seconds after the initiation of injection of contrast material, respectively. Iodized-oil CT was performed two weeks after angiography and infusion of iodized-oil. Masses were divided into three groups, according to size ; 1-20mm (n=34), 21-40mm (n=26), and over 40mm (n=19). Contrast enhancement patterns of tumors compared with attenuation of surrounding liver parenchyma, were cheracterized as one of four types, as follows : high, iso, low and mixed attenuation. Seventy-three of 79 HCC nodules detected on iodized-oil CT (92%) were detected on three-phase spiral CT. In the 1-20mm group, masses showed high-attenuation in the arterial dominant phase(19/34, 55.9%), and iso-attenuation in the portal dominant phase(16/34, 47.1 %) and delayed phase(18/34, 52.9%). In the 21-40mm group, masses showed high-attenuation in the arterial dominant phase(21/26, 80.8 %), low-attenuation in the portal dominant phase(13/26, 50%) and delayed phase(21/26, 80.8 %). In the over 40m group, the masses showed mixed-attenuation in the arterial dominant phase(9/19, 47.4%), low-attenuation in the portal dominant phase(12/19, 63.2%), and delayed phase(16/1hase(12/19, 63.2%), and delayed phase(16/19, 84.2 %). The most common enhancement pattern was high(arterial dominant)-iso(portal dominant)-iso(delayed) in the 1-20 mm group (8/34, 23.5 %), high-low-low in the group 21-40 mm (8/26, 30.8%), and mixed-low-low in the over 40mm group (5/19, 26.3%). Hepatocellular carcinomas showed variable enhancing patterns according to the size of the tumor on three-phase spiral CT. Understanding these enhancing characteristics of HCCs on three-phase spiral CT may be helpful in their diagnosis
Energy Technology Data Exchange (ETDEWEB)
Kwon, Ju Bae; Kim, Yong Soo; Rhim, Hyun Chul; Koh, Byung Hee; Cho, On Koo; Kim, Bong Soo; Park, Dong Woo; Park, Choong Ki [Hanyang Univ. College of Medicine, Seoul (Korea, Republic of)
2001-01-01
To determine the number of multiple alternating layers of liver abscess, and changes in this number, as revealed by spiral CT, and to ascertain which factors are related to changes occurring during the three phase of this modality. Using three-phase sprial CT imagingewe studied 26 cases of liver abscess (pyogenic: amebi = 23:3). The number of layers comprising the abscess, as seen on postcontrast CT scans, was determined during the arterial (30sec), portal (70sec),and delayed (220sec) phase, and all cases were assigned to one of to groups according to changes in the number of layers observed during the three phases. With regard to underlying disease, the two groups were compared in terms of the presence of abscess and of diabetes mellitus, CT interval (time from oneset of symptoms to CT scanning), microbial agent (pyogenic vs. amebic), and the largest diameter of abscess as revealed by CT. Except in one case, three or four alternating layers (in 13(50%) and 7(27%) cases, respectively) were seen only during the arterial and portal phase. During each of the three phase and especially the delayed phase, where it was present in 25 of cases (96%)-two alternating layers (2:2:2) was the most common pattern, with a 3:3:3 pattern occurring in one case. All 12 cases (46%) in the unchanging-layer group showed one of three two patterns. All changing-layer group cases (14;54%) demonstrated three or four layers during the arterial and portal phase but only two during the delayed phase. The CT interval was the only significantly different factor between the two groups. During the first week, the number of cases in the unchanging-layer group was much higher than in the changing layergroup (86%, 14%), but during the second week this situation reversed (25%, 75%). Our study reveals that on three-phase dynamic CT images, a characteristic enhancement feature of liver abscess is three or four layers during the arterial and portal phases, with reduction to two layers during the delayed phase. This change, as revealed by sprial CT, is rare during the week following the oneset of symptoms, but common during the second week.
A Mean Field Model With Two Order Parameters for Three-Phase Coexistence Near the Tricritical Point
SAL?HO?LU, S.
1998-01-01
This study gives a mean field model with two order parameters for three-phase coexistence near the multicritical point. The critical exponents calculated from our model are the tricritical exponents for the order parameters, susceptibility and the specific heat. Hence, our mean field model describes adequately the tricritical behaviour of a system in the region of three-phase coexistence.
Performance Analysis of Fuzzy Flatness Based Speed Control of Three Phase Induction Motor
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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.
Srinivas, S.; Ramachandrasekhar, K.
2010-06-01
A dual two-level inverter fed induction motor with open-end windings is capable of generating a three-level output voltage. Several, sine-triangle and space vector pulse width modulation (PWM) switching strategies are presented for the dual-inverter scheme either using space-vector or carrier-based implementation. In this paper, a hybrid PWM switching strategy for the dual-inverter scheme is proposed employing sine-triangle PWM (SPWM) and space vector PWM (SVPWM) for the individual inverters. SPWM is theoretically analyzed and space vector based implementation of SPWM is presented using a simple offset-time concept. This is exploited to implement the hybrid PWM switching strategy for the dual two-level inverter. The implementation of the hybrid PWM switching strategy proposed in this paper do not require any look-up tables, the switching is totally automatic obviating the time-consuming task of sector identification. The implementation of the hybrid PWM scheme requires only the three instantaneous phase reference voltages corresponding to the reference space vector. The third harmonic component in the voltage appearing across the motor phase windings in the induction motor is significantly reduced (by 50%) with the use of the proposed hybrid PWM scheme as compared to the use of the PWM scheme presented earlier. Also, the percentage weighted total harmonic distortion (%WTHD) of the output voltage is significantly reduced in the entire range of speed of the induction motor driven by the dual-inverter scheme.
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...
International Nuclear Information System (INIS)
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 sensitivintigraphy 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
Three-phase metal kinetics in terrestrial invertebrates exposed to high metal concentrations
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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.
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.
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.
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.
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.
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.
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.
Neuro-Fuzzy based Controller for a Three- Phase Four-Wire Shunt Active Power Filter
Mridul Jha; Dubey, S. P.
2011-01-01
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 r...
Sharing of nonlinear load in parallel-connected three-phase converters
DEFF Research Database (Denmark)
Borup, Uffe; Blaabjerg, Frede
2001-01-01
In this paper, a new control method is presented which enables equal sharing of linear and nonlinear loads in three-phase power converters connected in parallel, without communication between the converters. The paper focuses on solving the problem that arises when two converters with harmonic compensation are connected in parallel. Without the new solution, they are normally not able to distinguish the harmonic currents that flow to the load and harmonic currents that circulate between the converters. Analysis and experimental results on two 90-kVA 400-Hz converters in parallel are presented. The results show that both linear and nonlinear loads can be shared equally by the proposed concept.
Fault Detection, Isolation and Control Reconfiguration of Three-Phase PMSM Drives
Meinguet, Fabien; Kestelyn, Xavier; Semail, Eric; Gyselinck, Johan
2011-01-01
This paper deals with on-line software fault detection and isolation method for a drive composed of a fourleg inverter and a three-phase permanent magnet synchronous machine. The considered faults are single-phase open-circuit and current sensor outage. The method is based on the monitoring of the abc currents with phase-locked loops and the 'CUSUM' algorithm for the decision system. The impact of the considered faults is examined: first, in case there is no modification of the control and th...
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...
A small and wide-range three-phase current sensor using a MI element
International Nuclear Information System (INIS)
This paper describes a compact three-phase electric current sensor using a magneto-impedance (MI) sensor for wide-range current sensing. The MI sensor is composed of a thin-film MI element and a bias coil. Double shields are used for high shielding performance maintaining compact size. Discrete sampling being employed and sensors being intermittently driven in a 3 ms period can achieve a low power consumption of 20 mW. Two kinds of alternating bias are used in the system to achieve a wide measurement range of 1:600. Furthermore, using optimized carrier electric current is shown to decrease the temperature dependence of the MI sensor
A laboratory grid simulator based on three-phase four-leg inverter : Design and implementation
DEFF Research Database (Denmark)
Li, Fei; Wang, Xiongfei
2011-01-01
This paper presents the design and implementation of a laboratory grid simulator which is used to test the grid-connected devices according to the strict standards. Three-phase four-leg inverter with direct voltage control in Natural Frame is adopted in this grid simulator, which significantly reduces the computing and realizing complexities. Proportional and resonant controller is utilized to regulate the output voltage. Furthermore, various feedback variables in the inner control loop are discussed and compared. The capacitor current feedback was identified to guarantee better stability and power quality. Experimental results verify the functionality and performances of the designed grid simulator.
Automatic start control for a three-phase electric motor using infrared sensors
Echenique Lima, Mario; Ramírez Arenas, Francisco; Rodríguez Pedroza, Griselda
2006-02-01
We introduce equipment for the automatic activation of a three-phase electric motor (1Hp, 3A, 240V AC) using 2 infrared sensors monitored by a Microchip microcontroller PIC16F62x@4Mhz for the control of a filling system. This project was carried out to Fabrica de Chocolates y Dulces Costanzo, where the automatization of cacao grain supply was required for a machine in charge of cleaning the cacao from its rind. This process demanded the monitoring of the filling level to avoid the spill of toasted cacao.
Comparative Study of Controller Design for Four Quadrant Operation of Three Phase BLDC Motor
Directory of Open Access Journals (Sweden)
Ms.K.Suganya*1
2014-03-01
Full Text Available 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 characteristics of the three control methods are investigated intensely and the advantages, disadvantages of each are compared to the others with the help of MATLAB simulink software.
A parametric study on unbalanced three phase islanded microgrids with inverter interfaced units
DEFF Research Database (Denmark)
Sanseverino, Eleonora Riva; Quang, Ninh Nguyen
2013-01-01
In this paper, the solution of the power flow for unbalanced three phase microgrids systems is proposed. The study aims at the integration of inverter interfaced units using the control law used for primary voltage and frequency regulation, so as to take into account possible small variations of these parameters to account for sudden load changes. The proposed study deals with unbalanced systems which is the typical case of small distribution systems and shows how the power losses term varies as the regulators parameters vary as well, thus showing that these are sensitive parameters that could have an important role in optimal management of such systems.
Gas hold-up in a three-phase reciprocating plate column
Nikolic, Ljubisa B.; Nikolic, Vesna D.; Veljkovic, Vlada B.; Skala, Dejan U.
2005-01-01
The influence of the geometry of a reciprocating plate column (diameter), superficial gas velocity, vibration intensity and content of the solid phase in the column on the gas hold-up in a three phase column (G–L–S) were investigated in this study. For comparison, the gas hold-up was also analyzed in a gas–liquid system (G–L) in the same type of column. Good agreement between the experimentally determined values of the gas hold-up and those calculated on the basis of the derived corre...
Somalia’s “Pirate Cycle”: The Three Phases of Somali Piracy
Lucas, Edward R.
2013-01-01
This article provides a theoretical framework for examining Somali piracy from its origins in the 1990s to the present. This analysis provides both a detailed description of the changing nature of piracy, as well as explanations for why these changes have occurred. The increase in pirate activity off Somalia from 1991 to 2011 did not occur in a steady linear progression, but took place in three separate phases. These three phases can be viewed in terms of a “cycle of piracy,” based on a t...
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...
Controlador repetitivo para inversores PWM com referência de freqüência variável
Scientific Electronic Library Online (English)
Leandro, Michels; Márcio, Stefanello; Hilton A., Gründling.
2009-09-01
Full Text Available Controladores repetitivos têm se mostrado eficazes na rejeição de distúrbios cíclicos em inversores de tensão modulados por largura de pulso. Contudo, observa-se que estes controladores têm seu desempenho comprometido caso seu período não seja sincronizado com o período do sinal de referência, o que [...] restringe o seu uso em aplicações de freqüência variável. Para mitigar este problema, é proposta uma modificação nestes controladores para adequá-los à aplicações com referência senoidal de freqüência 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 especifiações distintas, são 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)
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.
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.
Plutonium partitioning in three-phase systems with water, granite grains, and different colloids.
Xie, Jinchuan; Lin, Jianfeng; Zhou, Xiaohua; Li, Mei; Zhou, Guoqing
2014-01-01
Low-solubility contaminants with high affinity for colloid surfaces may form colloid-associated species. The mobile characteristics of this species are, however, ignored by the traditional sorption/distribution experiments in which colloidal species contributed to the immobile fraction of the contaminants retained on the solids as a result of centrifugation or ultrafiltration procedures. The mobility of the contaminants in subsurface environments might be underestimated accordingly. Our results show that colloidal species of (239)Pu in three-phase systems remained the highest percentages in comparison to both the dissolved species and the immobile species retained on the granite grains (solid phase), although the relative fraction of these three species depended on the colloid types. The real solid/liquid distribution coefficients (K s/d) experimentally determined were generally smaller than the traditional K s/d (i.e., the K s+c/d in this study) by ~1,000 mL/g for the three-phase systems with the mineral colloids (granite particle, soil colloid, or kaolinite colloid). For the humic acid system, the traditional K s/d was 140 mL/g, whereas the real K s/d was approximately zero. The deviations from the real solid/liquid K s/d were caused by the artificially increased immobile fraction of Pu. One has to be cautious in using K s/d-based transport models to predict the fate and transport of Pu in the environment. PMID:24562456
Four-branch Star Hybrid Power Filter for Three-phase Four-wire Systems
DEFF Research Database (Denmark)
Blaabjerg, Frede; Teodorescu, Remus
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 can work either as a passive filter or as a hybrid filter. The paper analyzes the proposed topology and derives fundamental concepts about the control of the resulting hybrid power filter. From this analysis, a specifc implementation of a three-phase four-wire hybrid power filter is presented as an illustrative application of the filtering topology. An extensive evaluation using simulation and experimental results is conducted in order to verify and validate the good performance of the proposed four-branch star passive/hybrid power filter.
Rana, Sohel; Alagirusamy, Ramasamy; Joshi, Mangala
2011-08-01
In the present work, single-walled carbon nanotubes were dispersed within the matrix of carbon fabric reinforced epoxy composites in order to develop novel three phase carbon/epoxy/single-walled carbon nanotube composites. A combination of ultrasonication and high speed mechanical stirring at 2000 rpm was used to uniformly disperse carbon nanotubes in the epoxy resin. The state of carbon nanotube dispersion in the epoxy resin and within the nanocomposites was characterized with the help of optical microscopy and atomic force microscopy. Pure carbon/epoxy and three phase composites were characterized for mechanical properties (tensile and compressive) as well as for thermal and electrical conductivity. Fracture surfaces of composites after tensile test were also studied in order to investigate the effect of dispersed carbon nanotubes on the failure behavior of composites. Dispersion of only 0.1 wt% nanotubes in the matrix led to improvements of 95% in Young's modulus, 31% in tensile strength, 76% in compressive modulus and 41% in compressive strength of carbon/epoxy composites. In addition to that, electrical and thermal conductivity also improved significantly with addition of carbon nanotubes. PMID:22103118
Modeling and analysis of airlift system operating in three-phase flow
Hu, Dong; Kang, Yong; Tang, Chuan-lin; Wang, Xiao-chuan
2015-03-01
Based on the momentum theorem, the fluid governing equation in a lifting pipe is proposed by use of the method combining theoretical analysis with empirical correlations related to the previous research, and the performance of an airlift pump can be clearly characterized by the triangular relationship among the volumetric flux of air, water and solid particles, which are obtained respectively by using numerical calculation. The meso-scale river sand is used as tested particles to examine the theoretical model. Results of the model are compared with the data in three-phase flow obtained prior to the development of the present model, by an independent experimental team that used the physical conditions of the present approach. The analytical error can be controlled within 12% for predicting the volumetric flux of water and is smaller than that (±16%) of transporting solid particles in three-phase flow. The experimental results and computations are in good agreement for air-water two-phase flow within a margin of ±8%. Reasonable agreement justifies the use of the present model for engineering design purposes.
Fluid dynamics and mixing in three-phase coal and oil residue hydrogenation sieve cascade reactors
Energy Technology Data Exchange (ETDEWEB)
Bakopoulos, A.
2001-09-01
The present process integration work employs two modified versions of the Bergius three-phase hydrogenation technology including the application of sieve cascade reactors. The first process operates at medium pressures (7-20 MPa and 470 {degree}C) for hydroprocessing of oil refinery vacuum and or atmospheric residue to lighter products, and the second for synthetic fuel production by the direct thermal and catalytic coal liquefaction at higher operating pressures (30 MPa and 470 {degree}C). Technical problems for the design of large-scale multistage reactors are analyzed. Fluid dynamics, in one-stage bubble columns, are presented including the theoretical prediction of Newtonian non-settling slurry circulatory flow. and the liquid slurry and gas dispersion mixing efficiency of the sieve cascade reactor. Scale-up methodologies are proposed for columns up to 4 m in diameter, and up to 50 m in height, based on measurements and operating experience with larger three-phase petrochemical reactors, and the existing cold flow mathematical models in slurry bubble columns. The basic geometrical parameters of the oil residue or coal hydrogenation multistage reactor are discussed, and the influence analyzed of the sieve tray geometry and stage number at high pressures and temperatures on the fluid dynamics, mixing, gas hold up and interfacial area. Evidence is established that the installation of suitably designed sieve trays, operated above the minimum required liquid and gas superficial velocity, can eliminate deficiencies in the existing gas distribution designs.
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.
Superconducting properties of barium in three phases under high pressure from first principles
International Nuclear Information System (INIS)
Electron—phonon coupling (EPC) in the three high-pressure phases of Ba is investigated using a pseudopotential plane-wave method based on density functional perturbation theory. The calculated values of superconducting critical temperature Tc of Ba—I and Ba—II under pressure are consistent well with the trends observed experimentally. Moreover, Ba—V is found to be superconducting with a maximum Tc exceeding 7.8 K at 45 GPa. With the increase of pressure, the values of Tc increase in Ba I and Ba—II but the value of Tc decreases in Ba—V. For Ba—I at pressures below 2 GPa, the increases of logarithmic average frequency ?log and electron—phonon coupling parameters ? both contribute to the enhancement of Tc. For all the three phases at pressures above 2 GPa, Tc is found to be primarily determined by ?. Further investigation reveals that for all the three phases, the change in ? with pressure can be explained mainly by change in the phonon frequency Thus for Ba—II and Ba—V, although they exhibit completely different superconducting behaviors, their superconductivities have the same origin; the pressure dependence of Tc is determined finally by the pressure dependence of phonon frequency. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
Design and Development of Gas-Liquid Cylindrical Cyclone Compact Separators for Three-Phase Flow
Energy Technology Data Exchange (ETDEWEB)
Mohan, R.S.; Shoham, O.
2001-01-10
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.
Effective properties of three-phase electro-magneto-elastic multifunctional composite materials
Lee, Jaesang; Boyd, James G., IV; Lagoudas, Dimitris C.
2003-08-01
Coupling between the electric field, magnetic field, and strain of composite materials is achieved when electro-elastic (piezoelectric) and magneto-elastic (piezomagnetic) particles are joined by an elastic matrix. Although the matrix is neither piezoelectric nor piezomagnetic, the strain field in the matrix couples the E field of the piezoelectric phase to the B field of the piezomagnetic phase. This three-phase electro-magneto-elastic composite should have greater ductility and formability than a two-phase composite in which E and B are coupled by directly bonding two ceramic materials with no compliant matrix. A finite element analysis and homogenization of a representative volume element is used to determine the effective electric, magnetic, mechanical, and coupled-field properties of an elastic (epoxy) matrix reinforced with piezoelectric and piezomagnetic fibers. The effective magnetoelectric moduli of this three-phase composite are, however, less than the effective magnetoelectric coefficients of a two-phase piezoelectric/piezomagnetic composite, because the epoxy matrix is not stiff enough to transfer significant strains between the piezomagnetic and piezoelectric fibers.
Molecular dynamics simulation of CO2 hydrates: Prediction of three phase coexistence line
Míguez, J. M.; Conde, M. M.; Torré, J.-P.; Blas, F. J.; Piñeiro, M. M.; Vega, C.
2015-03-01
The three phase equilibrium line (hydrate-liquid water-liquid carbon dioxide) has been estimated for the water + carbon dioxide binary mixture using molecular dynamics simulation and the direct coexistence technique. Both molecules have been represented using rigid nonpolarizable models. TIP4P/2005 and TIP4P/Ice were used for the case of water, while carbon dioxide was considered as a three center linear molecule with the parameterizations of MSM, EPM2, TraPPE, and ZD. The influence of the initial guest occupancy fraction on the hydrate stability has been analyzed first in order to determine the optimal starting configuration for the simulations, paying attention to the influence of the two different cells existing in the sI hydrate structure. The three phase coexistence temperature was then determined for a pressure range from 2 to 500 MPa. The qualitative shape of the equilibrium curve estimated is correct, including the high pressure temperature maximum that determines the hydrate re-entrant behaviour. However, in order to obtain quantitative agreement with experimental results, a positive deviation from the classical Lorentz-Berthelot combining rules must be considered.
Fuzzy Logic Controller Based Three-phase Shunt Active Filter for Line Harmonics Reduction
Directory of Open Access Journals (Sweden)
C. Sharmeela
2007-01-01
Full Text Available 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 six controllable switches. The AC side of the inverter is connected in parallel with the other nonlinear loads through a filter inductance. The DC side of the inverter is connected to a filter capacitor. The Fuzzy Controller (FC is used to shape the current through the filter inductor such that the line current is in phase with and of the same shape as the input voltage. The results of the computer simulation prove that the injected harmonics are greatly reduced, system efficiency and power factor are improved.
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
International Nuclear Information System (INIS)
Homogenization of linear viscoelastic heterogeneous media is here extended from two phase inclusion-matrix media to three phase inclusion-matrix media. Each phase obeying to a compressible Maxwellian behaviour, this analytic method leads to an equivalent elastic homogenization problem in the Laplace-Carson space. For some particular microstructures, such as the Hashin composite sphere assemblage, an exact solution is obtained. The inversion of the Laplace-Carson transforms of the overall stress-strain behaviour gives in such cases an internal variable formulation. As expected, the number of these internal variables and their evolution laws are modified to take into account the third phase. Moreover, evolution laws of averaged stresses and strains per phase can still be derived for three phase media. Results of this model are compared to full fields computations of representative volume elements using finite element method, for various concentrations and sizes of inclusion. Relaxation and creep test cases are performed in order to compare predictions of the effective response. The internal variable formulation is shown to yield accurate prediction in both cases. (authors)
Design for size and weight reduction of lap-winding type three-phase variable inductor
Nakamura, Kenji; Honma, Koya; Ohinata, Takashi; Arimatsu, Kenji; Ichinokura, Osamu
2015-05-01
Variable inductors have a simple structure that consists of only magnetic core and primary dc and secondary ac windings, but can control effective inductance of the secondary ac winding by the primary dc current due to magnetic saturation effect. Hence, the variable inductors can be applied as a var compensator in electric power systems. In a previous paper, a lap-winding type three-phase variable inductor, which has the primary dc and secondary ac windings concentrically arranged on the same leg, was presented. It has a good controllability and low distortion current. This paper describes size and weight reduction of the lap-winding type three-phase variable inductor by focusing on the leg width. First, an initial design method of the leg width considering the influence of the dc-biased magnetization is presented. Next, a detailed design of the leg width for the size and weight reduction of the proposed variable inductor is described. Finally, characteristics of the size- and weight-reduced variable inductor were compared to those of the previous variable inductor. It is demonstrated that the core diameter is reduced by about 6% and the weight is decreased by about 50% in comparison with the previous variable inductor.
POWER FACTOR IMPROVEMENT IN THREE PHASE AC-AC CONVERTER THROUGH MODIFIED SPWM
Directory of Open Access Journals (Sweden)
P.VASUKI,
2011-02-01
Full Text Available Recently, a new generation of ac-ac single-phase and three-phase power converters with more commutations per half cycle has been proposed for ac power due to the increasing availability and power capability of high frequency controlled-on and off power emiconductor switching devices. This paper presents three phase ac-acconverter whose control strategy is based on modified sinusoidal ulse-width modulation switching technique. As majority of the industrial loads are being inductive, the power factor is less. To improve the power factor, the delayed current is shifted to the input voltage, through a modification of the classical sinusoidal pulse width modulation switching technique. In this way, the decrease in the phase angle between the input current and voltage is feasible, and consequently, high cost compensation capacitors can be avoided. The improvement of power factor through this switching technique on the proposed converter is investigated and verified via simulation using the software Matlab/Simulink.
Prediction of Riser Gas Holdup in Three- Phase External Loop Air Lift Fluidized Bed Reactor
Directory of Open Access Journals (Sweden)
Sivakumar Venkatachalam
2010-07-01
Full Text Available Hydrodynamics is an important issue for design and development of three phase external-loop airlift fluidized bed. This paper deals on the experimental investigations on the effect of superficial gas and liquid velocities and properties of solids on the riser gas holdup of a three phase external-loop airlift fluidized bed reactor and it was characterized using Newtonian and non Newtonian systems. Water, 65% and 85% of glycerol and n-butanol were used as Newtonian liquids and different concentration of Carboxyl Methyl Cellulose (CMC i.e., 0.2%, 0.5% and 1% were used as non Newtonian liquids. Spherical glass beads, bearl saddles and rasching rings of different sizes were used as solid phase. The phase flow rates and properties of solid particle had significant effect on the hydrodynamic characteristics of the external-loop airlift fluidized bed reactor such as riser gas holdup. Unified correlations have been developed to estimate the riser gas holdup as a function of superficial phase velocities, properties of solid particle and physical properties of both Newtonian and Non-Newtonian liquid systems. The predicting ability of the correlations were tested with the experimental data and found to be good fit with an absolute average relative error (AARD of ± 9.7 % for riser gas holdup.
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.
Molecular dynamics simulation of CO2 hydrates: Prediction of three phase coexistence line.
Míguez, J M; Conde, M M; Torré, J-P; Blas, F J; Piñeiro, M M; Vega, C
2015-03-28
The three phase equilibrium line (hydrate-liquid water-liquid carbon dioxide) has been estimated for the water + carbon dioxide binary mixture using molecular dynamics simulation and the direct coexistence technique. Both molecules have been represented using rigid nonpolarizable models. TIP4P/2005 and TIP4P/Ice were used for the case of water, while carbon dioxide was considered as a three center linear molecule with the parameterizations of MSM, EPM2, TraPPE, and ZD. The influence of the initial guest occupancy fraction on the hydrate stability has been analyzed first in order to determine the optimal starting configuration for the simulations, paying attention to the influence of the two different cells existing in the sI hydrate structure. The three phase coexistence temperature was then determined for a pressure range from 2 to 500 MPa. The qualitative shape of the equilibrium curve estimated is correct, including the high pressure temperature maximum that determines the hydrate re-entrant behaviour. However, in order to obtain quantitative agreement with experimental results, a positive deviation from the classical Lorentz-Berthelot combining rules must be considered. PMID:25833594
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.
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.
Comparison of Ion Transfer Thermodynamics at Microfluidic and Droplet-Based Three Phase Electrodes
International Nuclear Information System (INIS)
Highlights: • Ion transfer processes at microfluidic three phase electrodes were studied. • The voltammetric peak potentials depend on ion hydrophobicity and concentration. • The model developed for droplet based systems can be used also in microfluidics. • The volumetric flow rate does not affect the recorded peak potentials. • Gibbs energies of ion transfer from water to N-octyl-2-pyrrolidone were determined. - Abstract: We have investigated whether the thermodynamic model developed for ion transfer processes across the liquid|liquid interface at a droplet-based three phase electrode (TPE) can be applied to a microfluidic system. We have compared effect of ion transfer potential and ion concentration on the voltammetric peak potential recorded at droplet and microfluidic TPEs. The results were analyzed in terms of the Nernst-like equation derived for droplet TPE. As a model reaction, electrooxidation of decamethylferrocene coupled to anion transfer from aqueous electrolyte solution to N-octyl-2-pyrrolidone (NOP) has been chosen. We have found that both ion effect and concentration effect are the same in the two systems and agree with the Nernst equation. This allows microfluidic TPEs to be used in electroanalysis. Additionally, Gibbs energies of transfer for different inorganic anions have been determined for the studied NOP water biphasic system
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.
PWM Technique to Overcome the Effect of High PAPR in Wireless Systems
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Omar Daoud
2014-07-01
Full Text Available Many current communication systems suffer from perf ormance degradation due to the high sensitivity to high power peaks especially in the nonlinear device s. The author introduces a new concept based on the Pulse Width Modulation (PWM, namely MIMO-OFDM syst em based PWM (MO-PWM to overcome this deficiency. Here, the peak-to-average power ratio ( PAPR problem in Orthogonal Frequency Division Multiplexing (OFDM technique is used as a criterio n to check the validity of the proposed work. Moreover, the proposed system work has been impleme nted over Field Programmable Gate Array (FPGA, which is designed to characterize both of the compl exity and the speed issues. The systems performance based MO-PWM and validity h ave been checked based on a numerical analysis and a conducted simulation. The simulation results show that the MO-PWM can clearly reduce the PAPR values nevertheless the used OFDM systems’ specific ations, and gives a promising results over some techniques found in the literature, such as clippin g, SLM and PTS under same bandwidth occupancy and system’s specifications.
Half bridge ZVS DC-DC converter with DCS PWM active clamp technique
Directory of Open Access Journals (Sweden)
JANAPATI SIVAVARA PRASAD
2012-10-01
Full Text Available
Half bridge (HB dc–dc converter is an attractive topology for middle power level applications owing to its simplicity. This paper presents 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 one of the two 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, an active clamp branch comprising an auxiliary switch and a diode is added across the isolation transformer primary winding in the half bridge converter to achieve ZVS for the other main switch by utilizing energy stored in the transformer leakage inductance. Moreover, the auxiliary switch also operates at ZVS and ZCS conditions. In addition, the proposed topology with DCS PWM control eliminates the ringing resulting from the oscillation between the transformer leakage inductance and the switches junction capacitances during the off-time period. Therefore, the proposed converter has a potential to operate at higher efficiencies and switching frequencies.