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1

Research on Passivity Based Controller of Three Phase Voltage Source PWM Rectifier

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, l...

Yin Hongren; De Zhang Li; Wang Mian; Wang Jiuhe

2012-01-01

2

Research on Passivity Based Controller of Three Phase Voltage Source PWM Rectifier

Directory of Open Access Journals (Sweden)

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.

Yin Hongren

2012-09-01

3

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, beca...

S Manivannan, S. Veerakuma; P Karuppusamy, A. Nandhakumar

2014-01-01

4

Directory of Open Access Journals (Sweden)

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.

S. Manivannan, S. Veerakuma

2014-01-01

5

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.

Miller, Stephanie Katherine Teixeira

6

This paper presents the analysis of a photovoltaicbases three-phase five level voltage source inverter(VSI) supplying induction motor driven waterpump. The VSI uses a unipolar PWM technique forproducing three phase 5 level voltage output andthis output is used to drive three-phase inductionmotor driving a pump load. Multilevel inverters areused for generating AC voltage from several levelsof DC voltages and enhance the performance of thesystem. The proposed system is used to reduce thefilteri...

Ajay Kumar Maurya, Kishore Chahar

2013-01-01

7

This paper proposes a novel method of suppressing the inrush current of transformers. A small-rated voltage-source PWM converter is connected in series to the transformers through a matching transformer. As the connected PWM converter performs a resistor for the source current, no inrush phenomena occurs. The required-ratings of the PWM converter, which performs the damping resistor for the inrush phenomena, is one-four-hundredth as compared to that of the main transformers in single-phase circuits. In three-phase circuits, it is one-nine-hundredth. The basic principle of the proposed method is discussed. Digital computer simulation is implemented to confirm the validity and excellent practicability of the proposed method using the PSCAD/EMTDC. A prototype experimental-model is constructed and tested. The experimental results demonstrate that the proposed method can perfectly suppress the inrush phenomena.

Yamada, Hiroaki; Tanaka, Toshihiko; Funabiki, Shigeyuki

8

Control and Modeling of Shaft Generator with PWM Voltage Source Inverter for ship

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...

Sathish Kumar T; Gowrishankar J

2012-01-01

9

Shunt PWM advanced var compensators based on voltage source inverters for Facts applications

Energy Technology Data Exchange (ETDEWEB)

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.

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

10

Modulation Index Effect on the 5-Level SHE-PWM Voltage Source Inverter

Directory of Open Access Journals (Sweden)

Full Text Available Harmonic content of the voltage source inverters is important and must be in the allowed ranges. Different method are proposed to decrease the Total Harmonic Distortion (THD and caused to be sinusoidal the output voltage of inverters. One of these methods is using multilevel structure. In this structure many important parameters which are effective on voltage source inverter operation that among them we can mention to modulation index (MI. Variation of modulation index can change the THD. One of the harmonic reduction methods is using multilevel structure. In this paper, a sample 5-level SHE-PWM voltage source inverter is presented and all equation and choosing switching angles for elimination desired harmonics from different order. To investigate the effective parameters on the inverter operation, a typical 5-level inverter is simulated in PSPICE software. The simulation has been done for different values of modulation and its effect on the inverter operation is evaluated.

Hassan Feshki Farahani

2011-02-01

11

Application of Electric Double Layer Capacitor to Single-Phase Composite PWM Voltage Source Inverter

This paper proposes an application of electric double layer capacitor (EDLC) to single-phase composite PWM voltage source inverter (VSI). The VSI consist of the normal single-phase bridge circuit and an additional arm. The two auxiliary self-turn-off devices of the arm avail to adopt a composite PWM control, which contributes to reduce the ripple in the ac output current. In the dc side, the dc current contains the ac component, which has twice the system frequency. Until now, LC series resonance circuit tuned to twice the utility frequency is necessary to connect to the smoothing capacitor in parallel. Hence, the smoothing capacitor is drastically reduced. The VSI is disadvantageous in maintenance to use storage battery in order to stabilize the dc voltage. This paper describes an application of EDLC to smoothing capacitor in the dc side of the PWM VSI. The EDLC absorbs the ac component with twice the utility frequency and the ripple caused by PWM switching included the dc pulsating current. The smooth dc current is obtained by using the EDLC. The experiment shows that the single-phase composite PWM VSI used for the utility connected residential photovoltaic power generation system (PV system).

Harada, Katsuhiko; Nonaka, Sakutaro

12

Simplified Three-Phase 18-Step Voltage-Source Inverter by Injecting Harmonics

A new method for reducing harmonics in the output voltage of a three-phase voltage source inverter is proposed. This method is applied to a conventional six-step inverter with a three-phase output transformer. In the proposed inverter, two capacitors are used as dc source; further, four auxiliary switching devices and a single-phase transformer are included in the inverter, and harmonics are injected to the neutral point of the three-phase transformer. As a result, the output voltage of the proposed inverter becomes almost equal to that of a conventional 18-step inverter, which has 18 switching devices and three three-phase output transformers. In this paper, the circuit performances and output voltage waveforms are discussed, and the optimum parameters are determined by taking into account the effect of harmonics reduction. Then, the characteristics of an inverter system connected to a grid are experimentally investigated. Furthermore, the ratings of several components are clarified by the theoretical results.

Masukawa, Shigeo

13

Current Tracking Control of Voltage Source PWM Inverters Using Adaptive Digital Signal Processing

An active filter (AF) is required to have a high control capability of tracking a time-varying current reference. However, a steady-state current error always exists if a conventional proportional and integral (PI) regulator is used because the current reference varies in time. This paper proposes the application of adaptive digital signal processing (ADSP) to the current control of voltage source PWM inverters. ADSP does not require any additional hardware. It can automatically minimize the mean square-error. Since the processing time available by a computer is limited, ADSP cannot eliminate higher order harmonics but can eliminate lower order harmonics such as 5th to 17th. Experimental results demonstrate that ADSP is useful for improving the reference tracking performance of voltage source inverters.

Fukuda, Shoji; Furukawa, Yuya

14

A Novel PWM Scheme for a Three-Level Voltage Source Inverter Fed Induction Motor

Directory of Open Access Journals (Sweden)

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.

J. Amarnath

2009-03-01

15

Analysis of Discontinuous Space Vector PWM Techniques for a Seven-Phase Voltage Source Inverter

Directory of Open Access Journals (Sweden)

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.

Mohd. Arif Khan

2012-03-01

16

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the analysis of a photovoltaicbases three-phase five level voltage source inverter(VSI supplying induction motor driven waterpump. The VSI uses a unipolar PWM technique forproducing three phase 5 level voltage output andthis output is used to drive three-phase inductionmotor driving a pump load. Multilevel inverters areused for generating AC voltage from several levelsof DC voltages and enhance the performance of thesystem. The proposed system is used to reduce thefiltering requirements and reduce the amplitude ofall harmonics at the output of the inverter. ThePower quality improves by reducing the harmonicslevel. The complete simulation model is simulatedin MATLAB/SIMULINK and validates thetheoretical considerations

Ajay Kumar Maurya, Kishore Chahar, Y. K. Chauhan

2013-03-01

17

Power electronics based microgrids consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of three-phase VSIs are derived. The proposed voltage and current inner control loops and the mathematical models of the VSIs were based on the stationary reference frame. A hierarchical control for the paralleled VSI system was developed based on three levels. The primary control includes the droop method and the ...

Vasquez, Juan Carlos; Guerrero, Josep M.; Savaghebi, Mehdi; Eloy-garcia, Joaquin; Teodorescu, Remus

2013-01-01

18

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. T...

Sunil Kumar Chaudhary; Jaffery, Z. A.

2012-01-01

19

Analysis of Peak-to-Peak Current Ripple Amplitude in Seven-Phase PWM Voltage Source Inverters

Directory of Open Access Journals (Sweden)

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.

Gabriele Grandi

2013-08-01

20

Power Electronic Transformer based Three-Phase PWM AC Drives

A Transformer is used to provide galvanic isolation and to connect systems at different voltage levels. It is one of the largest and most expensive component in most of the high voltage and high power systems. Its size is inversely proportional to the operating frequency. The central idea behind a power electronic transformer (PET) also known as solid state transformer is to reduce the size of the transformer by increasing the frequency. Power electronic converters are used to change the frequency of operation. Steady reduction in the cost of the semiconductor switches and the advent of advanced magnetic materials with very low loss density and high saturation flux density implies economic viability and feasibility of a design with high power density. Application of PET is in generation of power from renewable energy sources, especially wind and solar. Other important application include grid tied inverters, UPS e.t.c. In this thesis non-resonant, single stage, bi-directional PET is considered. The main objective of this converter is to generate adjustable speed and magnitude pulse width modulated (PWM) ac waveforms from an ac or dc grid with a high frequency ac link. The windings of a high frequency transformer contains leakage inductance. Any switching transition of the power electronic converter connecting the inductive load and the transformer requires commutation of leakage energy. Commutation by passive means results in power loss, decrease in the frequency of operation, distortion in the output voltage waveform, reduction in reliability and power density. In this work a source based partially loss-less commutation of leakage energy has been proposed. This technique also results in partial soft-switching. A series of converters with novel PWM strategies have been proposed to minimize the frequency of leakage inductance commutation. These PETs achieve most of the important features of modern PWM ac drives including 1) Input power factor correction, 2) Common-mode voltage suppression at the load end, 3) High quality output voltage waveform (comparable to conventional space vector PWM modulated two level inverter) and 4) Minimization of output voltage loss, common-mode voltage switching and distortion of the load current waveform due to leakage inductance commutation. All of the proposed topologies along with the proposed control schemes have been analyzed and simulated in MATLABSimulink. A hardware prototype has been fabricated and tested. The simulation and experimental results verify the operation and advantages of the proposed topologies and their control.

Basu, Kaushik

21

Directory of Open Access Journals (Sweden)

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

Sunil Kumar Chaudhary

2012-10-01

22

A current-error space-vector-based PWM hysteresis controller is proposed for three-level voltage source inverter fed induction motor drive applications. A hexagonal boundary for the current-error space vector is formed by sensing the current-error space vector along three different axes, which are 120 degrees apart and are orthogonal to machine phase axes. Only the adjacent inverter voltage vectors forming a triangular sector, in which tip of the machine voltage vector lies, are switched to k...

Tekwani, Pn; Kanchan, Rs; Gopakumar, K.

2005-01-01

23

Sine Carrier for Fundamental Fortification in Three Phase Z-Source PWM Inverters

Directory of Open Access Journals (Sweden)

Full Text Available This paper deals with a novel natural sampled pulse width modulation strategy for three phase Z-source inverter through carrier modification. The proposed sine carrier method, which uses the conventional sinusoidal reference signal and a sine carrier, has a better harmonic spectrum and a higher fundamental component compared to the conventional triangular carrier based PWM. The sine carrier PWM enhances the fundamental output voltage while keeping the total harmonic distortion lower without involving changes in device switching loss. The detailed comparison of harmonic content and fundamental component of the sine carrier PWM output with the results obtained for the conventional PWM is also presented. Microcontroller is chosen for the hardware implementation of the switching strategy, mainly due to its high computation speed which can ensure the accuracy of the instants that gating signals are generated.

Shajith Ali

2009-12-01

24

DEFF Research Database (Denmark)

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.

Vasquez, Juan Carlos; Guerrero, Josep M.

2013-01-01

25

Intelligent Optimize Design of LCL Filter for Three-Phase Voltage-Source PWM Rectifier

DEFF Research Database (Denmark)

Compared to traditional L filter, a LCL filter is more effective on reducing harmonic distortion at switch frequency. So it is important to choose the LCL filter parameters to achieve good filtering effect. This paper introduces some traditional design methods. Design of a LCL filter by genetic algorithm (GA) and particle swam optimization (PSO) are presented in this paper and comparison of the two intelligent optimization. Simulation result and calculate data are provided to prove that intelligent optimization are more effective and simple than traditional methods.

Sun, Wei; Chen, Zhe

2009-01-01

26

Intelligent Optimize Design of LCL Filter for Three-Phase Voltage-Source PWM Rectifier

Compared to traditional L filter, a LCL filter is more effective on reducing harmonic distortion at switch frequency. So it is important to choose the LCL filter parameters to achieve good filtering effect. This paper introduces some traditional design methods. Design of a LCL filter by genetic algorithm (GA) and particle swam optimization (PSO) are presented in this paper and comparison of the two intelligent optimization. Simulation result and calculate data are provided to prove that intel...

Sun, Wei; Chen, Zhe; Wu, Xiaojie

2009-01-01

27

Directory of Open Access Journals (Sweden)

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.

Zhongjiu Zheng

2011-08-01

28

Converter-flux-based current control of voltage source PWM rectifiers - analysis and implementation

Energy Technology Data Exchange (ETDEWEB)

Pulsewidth-modulated (PWM) rectifier technology is increasingly used in industrial applications like variable-speed motor drives, since it offers several desired features such as sinusoidal input currents, controllable power factor, bidirectional power flow and high quality DC output voltage. To achieve these features, however, an effective control system with fast and accurate current and DC voltage responses is required. From various control strategies proposed to meet these control objectives, in most cases the commonly known principle of the synchronous-frame current vector control along with some space-vector PWM scheme have been applied. Recently, however, new control approaches analogous to the well-established direct torque control (DTC) method for electrical machines have also emerged to implement a high-performance PWM rectifier. In this thesis the concepts of classical synchronous-frame current control and DTC-based PWM rectifier control are combined and a new converter-flux-based current control (CFCC) scheme is introduced. To achieve sufficient dynamic performance and to ensure a stable operation, the proposed control system is thoroughly analysed and simple rules for the controller design are suggested. Special attention is paid to the estimation of the converter flux, which is the key element of converter-flux-based control. Discrete-time implementation is also discussed. Line-voltage-sensorless reactive reactive power control methods for the L- and LCL-type line filters are presented. For the L-filter an open-loop control law for the d-axis current reference is proposed. In the case of the LCL-filter the combined open-loop control and feedback control is proposed. The influence of the erroneous filter parameter estimates on the accuracy of the developed control schemes is also discussed. A new zero vector selection rule for suppressing the zero-sequence current in parallel-connected PWM rectifiers is proposed. With this method a truly standalone and independent control of the converter units is allowed and traditional transformer isolation and synchronised-control-based solutions are avoided. The implementation requires only one additional current sensor. The proposed schemes are evaluated by the simulations and laboratory experiments. A satisfactory performance and good agreement between the theory and practice are demonstrated. (orig.)

Poellaenen, R.

2003-07-01

29

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 f...

Zhongjiu Zheng; Guofeng Li; Ninghui Wang

2011-01-01

30

Microcontroller based PWM controlled four switch three phase inverter fed induction motor drive

This paper presents PIC microcontroller based PWM inverter controlled four switch three phase inverter (FSTPI) fed Induction Motor drive. The advantage of this inverter that uses of 4 switches instead of conventional 6 switches is lesser switching losses, lower electromagnetic interference (EMI), less complexity of control algorithms and reduced interface circuits. Simulation and experimental work are carried out and results presented to demonstrate the feasibility of the proposed approach. S...

Mohanty Kant Nalin; Muthu Ranganath

2010-01-01

31

Microcontroller based PWM controlled four switch three phase inverter fed induction motor drive

Directory of Open Access Journals (Sweden)

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.

Mohanty Kant Nalin

2010-01-01

32

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...

Cavagnino, Andrea; Boglietti, Aldo; Bojoi, Iustin Radu; Tenconi, Alberto

2008-01-01

33

Three Phase Six-Switch PWM Buck Rectifier with Power Factor Improvement

DEFF Research Database (Denmark)

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.

Zafar Ullah Khan, M; Mohsin Naveed, M.

2013-01-01

34

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.

35

Directory of Open Access Journals (Sweden)

Full Text Available This paper explains that how to develop and design, control of single phase to three phase drive system. The proposed topology of drive system consisting of two parallel connected rectifiers, inverter and induction motor, connected through inductor and capacitor, where used to produce balanced output to the motor drive. The main objective of this proposed method is to reduce the circulating currents and harmonic distortions at the converter input side, here the control strategy of drive system is PWM (pulse width modulations techniques control strategy, the proposed topology also provides fault compensation in the case of short circuit faults and failure of switches for uninterrupted Power supplies. We also develop and simulate the MATLAB models for proposed drive system, by using MATLAB/ Simulink the output results simulate and observed.

Ramakrishna Manohar Anaparthi

2014-12-01

36

Directory of Open Access Journals (Sweden)

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.

VISHNU MOHAN MISHRA

2012-03-01

37

DEFF Research Database (Denmark)

A comparison between two current control methods of grid side inverter, PI current control and Robust Forward control is made. PI control is implemented in d-q synchronous frame while Forward is implemented in abc stationary frames.The report contains both simulations and experimental test wich were made at a reduced scale ( 2.2 kW). The constant power test showed that both method have good results which can respect existing grid codes. The constant power test showed that both method have good results which can respect existing grid codes.

Lar, Ionut Andrei; Radulescu, Mircea

2012-01-01

38

Iron Loss Calculation Method of Filter Inductor Core on a Single-Phase PWM Voltage Source Inverter

The authors have reported a novel iron loss calculation method based on a loss-map of the magnetic materials. A distinctive feature of this method is that the iron loss on the inductors can easily be calculated in many kinds of converters. In this paper, a novel iron loss calculation method of the ac filter inductor on the PWM inverter by using the loss-map is described. This method enables to calculate the iron loss due to the dynamic minor loops by using the loss map and executing the easy circuit-simulation. The relation between the control method for the PWM inverter and the iron loss is discussed. Finally, the effectiveness of this method is verified through 500W experimental set-up.

Iyasu, Seiji; Shimizu, Toshihisa; Ishii, Ken-Ichiro

39

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the comparison of Unipolar Inverted Sine Carrier Pulse Width Modulation (UISCPWM techniques for the Cascaded Multi Level Inverter (CMLI. Due to switch combination redundancies, there are certain degrees of freedom to generate the multilevel AC output voltage. This paper presents the use of Control Freedom Degree (CFD combination. The effectiveness of the pulse width modulation strategies developed using CFD are demonstrated using simulation. The results indicate that the chosen five level inverter triggered by the developed UISC phase shift PWM and UISC variable frequency PWM strategy with sine and stepped wave references and UISC alternate phase opposition disposition PWM strategy with 60 degree reference exhibit reduced harmonics and UISC carrier overlapping PWM provides higher fundamental RMS output voltage for all three chosen references. Simulations are performed using MATLAB-SIMULINK.

C. R. Balamurugan

2012-11-01

40

Energy Technology Data Exchange (ETDEWEB)

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.

Chen Lei, E-mail: stclchen1982@yahoo.com.c [R and D Center of Applied Superconductivity, Huazhong University of Science and Technology, Wuhan 430074 (China); Tang Yuejin; Shi Jing; Li Zhi; Ren Li; Cheng Shijie [R and D Center of Applied Superconductivity, Huazhong University of Science and Technology, Wuhan 430074 (China)

2010-02-01

41

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.

42

Power supplies used on the electric power environment test process for electronic products and audio-amplifiers are required to generate arbitrary ac voltage waveforms in the wide frequency range. Traditionally, analogue amplifier technologies have been used for those application even though those have the disadvantages of low-efficiency, bulky in volume, and heavy in weight. Recently, however, research on the arbitrary waveform power generator becomes to be attractive among power electronics engineers, because the audio amplifiers utilizes the D-Mode switching technologies have been move into the market. This paper presents an arbitrary ac power generator utilizes a novel instantaneous waveform control method for a single-phase voltage source PWM inverter. A remarkable feature of this control method is that an adaptive frequency band-pass filter based on a rotation frame transformation and a command generator on the rotation frame is used. The proposed method can suppress the resonance caused by the LC filter at the output line, and hence it enables to generate a rectangular voltage waveform without overshoot. The command generator generates both an instantaneous frame angle and accurate voltage commands on the rotating frame from one an analogue signal. The effectiveness of this method is verified through 500W experimental set-up.

Hashino, Satoshi; Wada, Keiji; Shimizu, Toshihisa

43

Comparative analysis of SPWM and SVPWM control for three phase inverter

Directory of Open Access Journals (Sweden)

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.

K. Vinoth Kumar

2010-07-01

44

This paper presents a three-phase PWM current source inverter-induction motor drive system with photovoltaic generation. The system is interacted to single-phase utility using PWM converter, and the photovoltaic arrays are connected to the dc link of the system by employing a step-down chopper. The chopper is operated on PWM switching, and contributes to maintain the maximum power of the arrays and to smooth the dc link current in the small dc reactor. The PWM converter can flow the power in bidirection between the system and the utility with a sinusoidal current in the ac side. In this paper, the system configuration and the control methods are shown. First of all, the PWM strategy of the chopper, which depends on the converter PWM operation, is explained in detail and the switching patterns are given. Next, the experimental and the theoretical results at the steady state operations are given, and it is shown that the use of the PWM chopper is effective for the improvement of the ac waveforms. Finally, the waveforms at the transient operation are given in the variable speed drive of the motor and the change of the sunlight quantity for the arrays. The results prove that the proposed system has good performances for the utilization of the photovoltaic power.

Neba, Yasuhiko; Esaki, Tomokazu

45

International Nuclear Information System (INIS)

This paper is concerned with the design and implementation of current control of three-phase PWM rectifier based on predictive control strategy. The proposed predictive current control technique operates with constant switching frequency, using space-vector modulation (SVM). The main goal of the designed current control scheme is to maintain the dc-bus voltage at the required level and to achieve the unity power factor (UPF) operation of the converter. For this purpose, two predictive current control algorithms, in the sense of deadbeat control, are developed for direct controlling input current vector of the converter in the stationary ?-? and rotating d-q reference frame, respectively. For both predictive current control algorithms, at the beginning of each switching period, the required rectifier average voltage vector allowing the cancellation of both tracking errors of current vector components at the end of the switching period, is computed and applied during a predefined switching period by means of SVM. The main advantages of the proposed predictive current control are that no need to use hysteresis comparators or PI controllers in current control loops, and constant switching frequency. Finally, the developed predictive current control algorithms were tested both in simulations and experimentally, and illustrative results are presented here. Results have proven excellent performance in steady and transient states, and verify the validity of the proposed pre verify the validity of the proposed predictive current control which is compared to other control strategies.

46

This paper proposes a new inrush current suppressor using a series-connected small-rated PWM converter for a transformer. The PWM converter is directly connected in series between the source and transformer without a matching transformer. The inrush phenomena of the matching transformer, thus, can be avoided. The control gain and required-ratings of the series-connected small-rated PWM converter is discussed in detail. The capacity of the dc capacitor of the PWM converter is also discussed considering the active power flows into the PWM converter. The PSCAD/EMTDC is used to verify the validity of the proposed inrush current suppressor. A prototype experimental model is constructed and tested. The experimental results demonstrate that the proposed suppressor can perfectly overcome the inrush phenomena of transformers.

Yamada, Hiroaki; Tanaka, Toshihiko; Funabiki, Shigeyuki

47

Three-phase Resonant DC-link Converter

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...

Munk-nielsen, Stig

1997-01-01

48

Optimum space vector PWM algorithm for three-level inverter

Directory of Open Access Journals (Sweden)

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.

B. Urmila

2011-09-01

49

International Nuclear Information System (INIS)

This paper proposes direct power control (DPC) for three-phase PWM rectifiers using a new switching table, without line voltage sensors. The instantaneous active and reactive powers, directly controlled by selecting the optimum state of the converter, are used as the PWM control variables instead of the phase line currents being used. The main goal of the control system is to maintain the dc-bus voltage at the required level, while input currents drawn from the power supply should be sinusoidal and in phase with respective phase voltages to satisfy the unity power factor (UPF) operation. Conventional PI and a designed fuzzy logic-based controller, in the dc-bus voltage control loop, have been used to provide active power command. A dSPACE based experimental system was developed to verify the validity of the proposed DPC. The steady-state, and dynamic results illustrating the operation and performance of the proposed control scheme are presented. As a result, it was confirmed that the novel DPC is much better than the classical one. Line currents very close to sinusoidal waveforms (THD < 2%) and good regulation of dc-bus voltage are achieved using PI or fuzzy controller. Moreover, fuzzy logic controller gives excellent performance in transient state, a good rejection of impact load disturbance, and a good robustness

50

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...

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

51

THREE-PHASE ACTIVE POWER FILTER CONTROLLER FOR BALANCED AND UNBALANCED NON-LINEAR LOAD

The active power filter produces equal but opposite harmonic currents to the point of connection with the nonlinear load. This results in a reduction of the original distortion and correction of the power factor. A threephase insulated gate bipolar transistor based current controlled voltage source inverter with a dc bus capacitor is used as an active filter. The firing pulses to the shunt active filter will be generated by using sine PWM method. The models for three-phase active power filter...

Nageswara Rao, G.; Dr.K. CHANDRA SEKHAR,; Sangameswara Raju, Dr P.

2010-01-01

52

Feedforward Synchronised PWM for Adjustable Speed AC Drives with Different Control Modes

DEFF Research Database (Denmark)

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.

Oleschuk, Valentin; Blaabjerg, Frede

2002-01-01

53

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.

Morimoto, Keiki; Doi, Toshimitsu; Manabe, Haruhiko; Ahmed, Tarek; Hiraki, Eiji; Lee, Hyun-Woo; Nakaoka, Mutsuo

54

A novel dynamic voltage restorer and its unbalanced control strategy based on space vector PWM

Energy Technology Data Exchange (ETDEWEB)

A novel dynamic voltage restorer which is composed of a conventional three-phase voltage source inverter and an emitter follower is presented in this paper to reduce the adverse effects on sensitive loads caused by three-phase supply voltage unbalance in distribution systems. The adverse effect caused by the negative sequence component of the supply voltage can be eliminated and the load voltage magnitude can be restored to specified value by using the three-phase voltage-source inverter. The emitter follower is capable of eliminating the adverse effect caused by the zero sequence component of the supply voltage. An unbalanced control strategy based on space vector PWM is presented to realize the fast dynamic response of the dynamic voltage restorer. Feasibility of this method is verified by digital simulation. (Author)

Hongfa Ding; Shu Shuangyan; Duan Xianzhong; Gao Jun [Huazhong Univ. of Science and Technology, Dept. of Electrical Power Engineering, Wuhan (China)

2002-11-01

55

Space Vector PWM Implementation for Z-Source Inverter

Directory of Open Access Journals (Sweden)

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.

K Veera Reddy

2014-06-01

56

THREE-PHASE ACTIVE POWER FILTER CONTROLLER FOR BALANCED AND UNBALANCED NON-LINEAR LOAD

Directory of Open Access Journals (Sweden)

Full Text Available The active power filter produces equal but opposite harmonic currents to the point of connection with the nonlinear load. This results in a reduction of the original distortion and correction of the power factor. A threephase insulated gate bipolar transistor based current controlled voltage source inverter with a dc bus capacitor is used as an active filter. The firing pulses to the shunt active filter will be generated by using sine PWM method. The models for three-phase active power filter controller for balanced and unbalanced non-linear load is made and is simulated using Matlab/simulink software.

G.NAGESWARA RAO

2010-09-01

57

Speed Control and THD for Three Phase Induction Motor Using Simulink

Directory of Open Access Journals (Sweden)

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.

Priya Janak 1

2014-06-01

58

DEFF Research Database (Denmark)

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.

Blaabjerg, Frede; Aquila, A. Dell?

2004-01-01

59

Directory of Open Access Journals (Sweden)

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.

Mechouma Rabiaa

2014-01-01

60

Directory of Open Access Journals (Sweden)

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 motor 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.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 this 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.

Rudolf Ribeiro Riehl

2012-04-01

61

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese 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.

Rudolf Ribeiro, Riehl; Ernesto, Ruppert.

2012-04-01

62

FPGA Based Three Phase Multilevel PWM Inverter

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents, a phase shifted carrier pulse width modulation is proposed, which can minimize the output total harmonic distortion and enhances the output voltages from five level inverter to multilevel topologies. Multilevel inverters are important for power electronics applications such as flexible AC transmission systems, renewable energy sources, unin terruptible power supplies and active power filters. Two novel methodologies adopting the phase shifted carrier pulse width modulation concept are proposed in this paper. The phase shifted carrier pulse width modulation cascaded multilevel inverter strategy minimized output total harmonic distortion and phase shifted carrier switching frequency optimal pulse width modulation cascaded multilevel inverters strategy enhances the output voltages. Field programmable gate array has been chosen to implement the pulse width modulation due its fast proto typing, simple hardware and software design. Simulation and Experimental results are provided.

Tamboli J. I.

2014-04-01

63

Pulse width Modulation Command Systems Used for the Optimization of Three Phase Inverters

This paper deals with a novel pulse width modulation (PWM) switching strategy for a voltage source inverter through carrier modification. The proposed discontinuous sine carrier PWM (DPWM1) method, which uses two modified sine waves, has a better spectral quality and a higher fundamental component. This improved waveform has been derived from the original sine PWM technique through the addition of the 17-percent third-harmonic component to the original sine reference.

Lucanu, M.; Tigaeru, L.; Ursaru, O.; Aghion, C.

2009-01-01

64

Three-phase Resonant DC-link Converter

DEFF Research Database (Denmark)

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.

Munk-Nielsen, Stig

1997-01-01

65

Comparative Study of Multicarrier PWM Techniques for a Modular Multilevel Inverter

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...

Rajan, M. S.; Seyezhai, R.

2014-01-01

66

Implementation of a Hybrid High Power Factor Three-Phase Unidirectional Rectifier

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 pr...

Ankusha Biradar,; Prof.Nagabhushan.Patil

2013-01-01

67

Modeling & Simulation of Fuel cell (Choi Model) based 3-Phase Voltage Source Inverter

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 ...

Gaurav Sachdeva

2011-01-01

68

Analysis of Input and Output Ripples of PWM AC Choppers

This paper presents an analysis of input and output ripples of PWM AC choppers. Expressions of input and output current and voltage ripples of single-phase PWM AC choppers are first derived. The derived expressions are then extended to three-phase PWM AC choppers. As input current and output voltage ripples specification alone cannot be used to determine the unique values of inductance and capacitance of the LC filters, an additional criterion based on the minimum reactive power is proposed. ...

Pekik Argo Dahono; Dessy Amirudin; Arwindra Rizqiawan; Deni

2008-01-01

69

Directory of Open Access Journals (Sweden)

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.

S. Elangovan

2014-07-01

70

Investigation of FPGA Based PWM Control Technique for AC Motors

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 harm...

Valantina Stephen; Padma Suresh

2013-01-01

71

Energy Technology Data Exchange (ETDEWEB)

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 to harmonic and reactive power compensation generated from any configuration of non-linear load. Under normal line conditions the UPS system works with universal filtering capabilities, such as compensating the input currents and output voltages. Two three-phase pulse width modulation (PWM) converters, called series and parallel active filters, are used to perform the series and parallel active power-line compensation. The series active power 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 power filter works as sinusoidal voltage source in phase with the input voltage, providing regulated and sinusoidal output voltages with low THD. Operation of a three-phase phase-locked loop (PLL) structure, used in the proposed line-interactive UPS implementation, is presented and experimentally verified under distorted utility conditions. The performance of the UPS system is evaluated in three-phase, four-wire systems. Digital simulations and experimental results are presented to confirm the theoretical studies. (author)

Oliveira da Silva, S.A. [CEFET-PR, Cornelio, Procopio (Brazil). Department of Electrical Engineering; Donoso-Garcia, P.; Cortizo, P.C.; Seixas, P.F. [Federal University of Minas Gerais, Belo Horizonte (Brazil). Department of Electronic Engineering

2004-07-01

72

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 Harmoni...

Naik R. L; Jangamshetti Suresh.H.

2014-01-01

73

Control to Three-phase Inverter by Sliding Mode

In this study, it is treated the modeling and the ordering of a three-phase inverter. The studied system is a load supplied with a three-phase inverter by means of a transformer. The ordering of the inverter is with PWM (pulse-width modulation/pulse-width Modulation) and its regulation is made by the sliding method. This method is presented in this document with its various laws. The simulation of the unit is made and the results presented.

Mouhamadou Thiam; Gustave Sow; Dorothé Azilinon; Lamine Thiaw; Fall, Salif S.; Momar Kassé; Alphousseyni Ndiaye

2014-01-01

74

Analysis of Model Predictive Current Control for Voltage Source Inverter

Directory of Open Access Journals (Sweden)

Full Text Available Model predictive control has become a promising control technology in power converter, because of the good dynamic response and accurate current tracking capability. This study mainly analyzes and verifies the Model Predictive Current control (MPC of a three-phase voltage sources converter. The MPC controller predicts the behavior of the converter for each possible voltage vector on each sampling interval. And a cost function is used to evaluate the voltage vector for the next sampling interval based the predicted load behavior. According to the assessment, an optimal voltage vector is selected and the corresponding switching state is applied to the converter during the next sampling interval. Finally, simulation and experimental results are demonstrated to validate the steady-state and dynamic performance of the proposed system.

Jingang Han

2013-09-01

75

Comparative Study of Multicarrier PWM Techniques for a Modular Multilevel Inverter

Directory of Open Access Journals (Sweden)

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.

M.S.Rajan

2014-01-01

76

Modeling & Simulation of Fuel cell (Choi Model based 3-Phase Voltage Source Inverter

Directory of Open Access Journals (Sweden)

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.

Gaurav Sachdeva

2011-10-01

77

Cascaded Nine Level Inverter Using Pulse Width Modulation And Hybrid PWM

Directory of Open Access Journals (Sweden)

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.

Rohini Sharma

2014-05-01

78

Single Phase Voltage Source Inverter Photovoltaic Application

Photovoltaic applications have been developing and spreading rapidly in recent times. This paper describes the control strategy of the Voltage Source Inverter that is the important tail end of many photovoltaic applications.In order to supply the grid with a sinusoidal line current without harmonic distortion, the inverter is connected to the supply network via a L-C-L filter. The output current is controlled by the hysteresis controller. To improve the behaviors of the L-C-L filter, active d...

Bauer, J.

2010-01-01

79

Single Phase Voltage Source Inverter Photovoltaic Application

Directory of Open Access Journals (Sweden)

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.

J. Bauer

2010-01-01

80

Analysis of Input and Output Ripples of PWM AC Choppers

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents an analysis of input and output ripples of PWM AC choppers. Expressions of input and output current and voltage ripples of single-phase PWM AC choppers are first derived. The derived expressions are then extended to three-phase PWM AC choppers. As input current and output voltage ripples specification alone cannot be used to determine the unique values of inductance and capacitance of the LC filters, an additional criterion based on the minimum reactive power is proposed. Experimental results are included in this paper to show the validity of the proposed analysis method.

Pekik Argo Dahono

2008-11-01

81

Analysis and Minimization of Output Current Ripple of Multiphase Carrier-Based PWM Inverters

Analysis and minimization of output current ripple of multiphase carrier-based PWM inverters are presented in this paper. Analytical expression of rms value of output current ripple of multiphase PWM inverters as a function of the reference signal is first derived. Based on this expression, it is shown that a pure sinusoidal signal is the optimum reference signal that results in minimum output current ripple. Different to three-phase PWM inverters, injection of harmonics into the sinusoidal r...

Pekik Argo Dahono

2010-01-01

82

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...

La Hidalga-w, F. J.; Malik, O.

2013-01-01

83

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

84

High performance direct instantaneous power control of PWM rectifiers

International Nuclear Information System (INIS)

This paper presents a new direct instantaneous power control (DPC) strategy for active rectifiers. In this novel scheme the PWM modulator has been utilized instead of the hysteresis comparators and switching table. The required converter voltage in each sampling period is directly calculated based on the reference and measured values of powers, system parameters, and the measured voltage of the AC source through simple equations which are wisely compensated for variations of the grid voltage during a sampling period. Then, the PWM generator generates the switching pulses for the voltage source converter. It is shown that the proposed DPC-PWM exhibits several features, such as a simple algorithm, constant switching frequency, robust to sampling frequency changes, robust to inductance values mismatch, and particularly it provides low sampling frequency. Extensive simulation and experimental results have proven the excellent performance and verify the validity and effectiveness of the proposed instantaneous power control scheme.

85

Generalized SVPWM Algorithm for Two Legged Three Phase Multilevel Inverter

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 ...

Devisree Sasi; Jisha Kuruvilla P; Anish Gopinath

2013-01-01

86

Comparison of a three phase single stage PV system in PSCAD and PowerFactory

The main objective of the project is to develop a Photovoltaic (PV) system using three phase Pulse Width Modulation (PWM) converter as the interfacing component in Power factory. Already existing model in Power factory tool uses static generator as the interfacing converter. Moreover the control technique implemented within the PV model is very basic. Aworking model is already available in PSCAD simulation tool using PWM converter but it is a very detailed one in terms of modeling which resul...

Jose, Della

2012-01-01

87

Control to Three-phase Inverter by Sliding Mode

Directory of Open Access Journals (Sweden)

Full Text Available In this study, it is treated the modeling and the ordering of a three-phase inverter. The studied system is a load supplied with a three-phase inverter by means of a transformer. The ordering of the inverter is with PWM (pulse-width modulation/pulse-width Modulation and its regulation is made by the sliding method. This method is presented in this document with its various laws. The simulation of the unit is made and the results presented.

Mouhamadou Thiam

2014-03-01

88

Directory of Open Access Journals (Sweden)

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.

Naik R. L

2014-07-01

89

Directory of Open Access Journals (Sweden)

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.

N. Belhaouchet

2008-03-01

90

Optimal condition of memristance enhancement circuit using external voltage source

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.

Tanaka, Hiroya; Tadokoro, Yukihiro; Iizuka, Hideo

2014-05-01

91

Power Loss Calculation and Thermal Modelling for a Three Phase Inverter Drive System

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...

Zhou, Z.; Khanniche, M. S.; Igic, P.; Towers, S. M.; Mawby, P. A.

2005-01-01

92

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...

V Arun, B. Shanthi

2013-01-01

93

Design of New Single-phase Multilevel Voltage Source Inverter

Multilevel inverters with more number of levels can produce high quality voltage waveforms. In this paper, a new single-phase structure for multilevel voltage source inverter is proposed which can generate a large number of levels with reduced number of IGBTs, gate driver circuits and diodes. Three algorithms for determination of dc voltage sources’ magnitudes are presented which provide odd and even levels at the output voltage waveform. A comparison is presented between proposed multileve...

Rasoul Shalchi Alishah; Daryoosh Nazarpour; Seyyed Hossein Hosseini; Mehran Sabahi

2014-01-01

94

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese 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 qu [...] aisquer 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. Abstract in english This paper presents a three-phase line-interactive uninterruptible power supply (UPS) system with active series-parallel power-line conditioning capabilities. Synchronous reference frame (SRF)-based controller is used for harmonic and reactive power compensation generated from any configuration of n [...] on-linear loads. Under normal line conditions the UPS system works with universal filtering capabilities, such as compensating the input currents and output voltages. Two three-phase pulsewidth modulation (PWM) converters, called series and parallel active filters, are used to perform the series and parallel active power-line compensation. The series active filter works as sinusoidal current source in phase with the input voltage, drawing from utility sinusoidal and balanced input currents with low total harmonic distortion (THD). The parallel active filter works as sinusoidal voltage source in phase with the input voltage, providing regulated and sinusoidal output voltages with low THD. The performance of the UPS system is evaluated in three-phase, four-wire systems. Experimental results are presented to confirm the theoretical studies.

Sérgio Augusto Oliveira da, Silva; Pedro F., Donoso-Garcia; Porfírio C., Cortizo; Paulo F., Seixas.

2005-06-01

95

Indirect Vector Control of Three Phase Induction Motor using PSIM

Directory of Open Access Journals (Sweden)

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.

Nagulapati Kiran

2014-03-01

96

Implementation of a Hybrid High Power Factor Three-Phase Unidirectional Rectifier

Directory of Open Access Journals (Sweden)

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.

Ankusha Biradar,

2013-03-01

97

Transistorized PWM inverter-induction motor drive system

This paper describes the development of a transistorized PWM inverter-induction motor traction drive system. A vehicle performance analysis was performed to establish the vehicle tractive effort-speed requirements. These requirements were then converted into a set of inverter and motor specifications. The inverter was a transistorized three-phase bridge using General Electric power Darlington transistors. The description of the design and development of this inverter is the principal object of this paper. The high-speed induction motor is a design which is optimized for use with an inverter power source. The primary feedback control is a torque angle control with voltage and torque outer loop controls. A current-controlled PWM technique is used to control the motor voltage. The drive has a constant torque output with PWM operation to base motor speed and a constant horsepower output with square wave operation to maximum speed. The drive system was dynamometer tested and the results are presented.

Peak, S. C.; Plunkett, A. B.

1982-01-01

98

Three phase downhole separator process

Three Phase Downhole Separator Process (TPDSP) is a process which results in the separation of all three phases, (1) oil, (2) gas, and (3) water, at the downhole location in the well bore, water disposal injection downhole, and oil and gas production uphole.

Cognata, Louis John (Baytown, TX)

2008-06-24

99

Design of New Single-phase Multilevel Voltage Source Inverter

Directory of Open Access Journals (Sweden)

Full Text Available Multilevel inverters with more number of levels can produce high quality voltage waveforms. In this paper, a new single-phase structure for multilevel voltage source inverter is proposed which can generate a large number of levels with reduced number of IGBTs, gate driver circuits and diodes. Three algorithms for determination of dc voltage sources’ magnitudes are presented which provide odd and even levels at the output voltage waveform. A comparison is presented between proposed multilevel inverter and conventional cascade topology. The proposed topology is analyzed by the experimental and simulation results.

Rasoul Shalchi Alishah

2014-07-01

100

Energy Technology Data Exchange (ETDEWEB)

In this paper, we study a new kind of continuous-alternating converters: a seven-level neutral point clamping (NPC) voltage source inverter (VSI). We propose this inverter for applications in high voltage and high power fields. In the first part, we develop the knowledge and the control models of this inverter using the connections functions of the semi-conductors. After that, we present two pulse width modulation (PWM) algorithms to control this converter using its control model. We propose these algorithms for digital implementation. This multilevel inverter is associated to the induction machine. The performances obtained are full of promise to use it in the high voltage and high power fields of electrical traction. (orig.)

Gheraia, H.; Berkouk, E.M. [ENP, Alger (Algeria). Lab. de Commande des Processus; Manesse, G. [CNAM-Paris (France). Lab. d' Electricite Industrielle

2001-08-01

101

Voltage Source Inverter/Converter for the Improvement of Power Quality Using Fuzzy Logic Controller

Directory of Open Access Journals (Sweden)

Full Text Available 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 harmonics generated by the non-linear load . This work is done to make an accurate comparison of the performance of fuzzy logic controller and classical control technique such as PI controller in compensating harmonics in the ac mains current. Fuzzy control rule design is based on the general dynamic behavior of the process. A novel control method is implemented for suppressing the harmonics. The compensation process is instantaneous, which is achieved without employing any complicated control logic. The control scheme is based on sensing line currents only; an approach different from convention ones, which are based on sensing harmonics of the nonlinear load. In the control scheme a hysteresis controller based on current control is employed to generate switching signals to the PWM converter.

T Jagan Mohan Rao

2014-05-01

102

A Comparative Study of Sinusoidal PWM and Space Vector PWM of a Vector Controlled BLDC Motor

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...

Lydia Anu Jose, K. B. Karthikeyan

2013-01-01

103

A Comparative Study of Sinusoidal PWM and Space Vector PWM of a Vector Controlled BLDC Motor

Directory of Open Access Journals (Sweden)

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.

LYDIA ANU JOSE, K.B.KARTHIKEYAN

2013-06-01

104

Investigation of FPGA Based PWM Control Technique for AC Motors

Directory of Open Access Journals (Sweden)

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.

Valantina Stephen

2013-02-01

105

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 s...

Chandra Babu Paduchuri; Subhransu Sekhar Dash; Subramani Chinnamuthu

2014-01-01

106

Energy Technology Data Exchange (ETDEWEB)

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.

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

107

A battery-based, low-noise voltage source

A highly stable, low-noise voltage source was designed to improve the stability of the electrode bias voltages of a Penning trap. To avoid excess noise and ground loops, the voltage source is completely independent of the public electric network and uses a 12 V car battery to generate output voltages of ±15 and ±5 V. First, the dc supply voltage is converted into ac-voltage and gets amplified. Afterwards, the signal is rectified, filtered, and regulated to the desired output value. Each channel can deliver up to 1.5 A. The current as well as the battery voltage and the output voltages can be read out via a universal serial bus (USB) connection for monitoring purposes. With the presented design, a relative voltage stability of 7×10-7 over 6.5 h and a noise level equal or smaller than 30 nV/?Hz is achieved.

Wagner, Anke; Sturm, Sven; Schabinger, Birgit; Blaum, Klaus; Quint, Wolfgang

2010-06-01

108

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

109

Performance Evaluation of Three Phase Bridge Module Type Diode Clamped Multilevel Inverter

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...

C R Balamurugan, S. P. Natarajan

2012-01-01

110

Shunt active filter algorithms for a three phase system fed to adjustable speed drive

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 bal...

Ch, Sujatha; Sravanthi.Kusam; Chandra Shek, Dr K.

2011-01-01

111

Analysis and Minimization of Output Current Ripple of Multiphase Carrier-Based PWM Inverters

Directory of Open Access Journals (Sweden)

Full Text Available Analysis and minimization of output current ripple of multiphase carrier-based PWM inverters are presented in this paper. Analytical expression of rms value of output current ripple of multiphase PWM inverters as a function of the reference signal is first derived. Based on this expression, it is shown that a pure sinusoidal signal is the optimum reference signal that results in minimum output current ripple. Different to three-phase PWM inverters, injection of harmonics into the sinusoidal reference signal is neither necessary nor useful. The rms values of output current ripple of 5-, 7-, and 9-phase PWM inverters under various reference signals are compared. Experimental results are included to show the validity of the analysis method.

Pekik Argo Dahono

2010-05-01

112

Measurements of power loss distribution in a typical stator core under PWM voltage excitation

International Nuclear Information System (INIS)

The pulse width modulated (PWM) inverter is widely used to feed small induction motors for variable speed and torque control. When a laminated stator core is energised in this way additional iron losses occur due to localised distorted flux. Flux density and power loss distribution under PWM and sinusoidal voltage excitations were measured in a typical induction motor stator core lamination at 1.3 T, 50 Hz by using a computer-aided magnetising system to set up flux distribution as would occur in a practical three-phase stator core. The iron loss increased 15-20% under PWM excitation. The loss increase under PWM excitation in the stator core laminations was 3% lower than in Epstein strips of the same electrical steel under the same conditions showing an effect of the magnetic circuit geometry

113

Measurements of power loss distribution in a typical stator core under PWM voltage excitation

Energy Technology Data Exchange (ETDEWEB)

The pulse width modulated (PWM) inverter is widely used to feed small induction motors for variable speed and torque control. When a laminated stator core is energised in this way additional iron losses occur due to localised distorted flux. Flux density and power loss distribution under PWM and sinusoidal voltage excitations were measured in a typical induction motor stator core lamination at 1.3 T, 50 Hz by using a computer-aided magnetising system to set up flux distribution as would occur in a practical three-phase stator core. The iron loss increased 15-20% under PWM excitation. The loss increase under PWM excitation in the stator core laminations was 3% lower than in Epstein strips of the same electrical steel under the same conditions showing an effect of the magnetic circuit geometry.

Tutkun, N. E-mail: tutkun@karaelmas.edu.tr; Moses, A.J

2003-06-01

114

Directory of Open Access Journals (Sweden)

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.

F. J. De la Hidalga-W

2013-01-01

115

Generalized SVPWM Algorithm for Two Legged Three Phase Multilevel Inverter

Directory of Open Access Journals (Sweden)

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.

Devisree Sasi

2013-07-01

116

Indirect Vector Control of Three Phase Induction Motor using PSIM

Directory of Open Access Journals (Sweden)

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

Nagulapati Kiran

2014-03-01

117

Three-phase electric drive with modified electronic smoothing inductor

DEFF Research Database (Denmark)

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.

Singh, Yash Veer; Rasmussen, Peter Omand

2010-01-01

118

Directory of Open Access Journals (Sweden)

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.

Valantina Stephen

2012-01-01

119

DEFF Research Database (Denmark)

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.

Mathe, Laszlo; Lungeanu, Florin

2010-01-01

120

Parallel operation of voltage-source converters: issues and applications

Energy Technology Data Exchange (ETDEWEB)

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)

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

121

Stable d-c high-voltage source

International Nuclear Information System (INIS)

The electric circuit is proposed and described of a stable high-voltage d-c source for supplying radiation detectors. The output of a stable a-c low-voltage source is connected to the input of an amplifier whose output is connected by capacitance of a capacitor to the transformer primary. A rectifier or a voltage multiplier with filter is connected to the transformer secondary, with a feedback inserted between the transformer secondary and the amplifier input circuit. (J.K.)

122

— 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 ...

M Neelu Kumar, P. Bhaskara Prasad

2013-01-01

123

Directory of Open Access Journals (Sweden)

Full Text Available In this study, a three-phase continuously controlled harmonic-free inductive static VAR compensator is presented. The compensator is built of a three-phase voltage source inverter based statcom. The phase currents of this compensator are linearly and continuously controlled by the statcom DC capacitor voltage. The control strategy is outlined by a process of forcing the capacitor voltage to follow a certain reference voltage which can be varied linearly from its maximum to its minimum values to produce balanced three-phase inductive currents varying in the range of zero to maximum value (I MAX The proposed compensator was verified on the computer program PSpice.

Abdulkareem Mokif Obais

2013-02-01

124

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: English Abstract in spanish 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.

Alberto, Berzov; Julio, Viola; José, Restrepo.

2012-09-01

125

Review of multilevel voltage source inverter topologies and control schemes

Energy Technology Data Exchange (ETDEWEB)

In this study, the most common multilevel inverter topologies and control schemes have been reviewed. Multilevel inverter topologies (MLIs) are increasingly being used in medium and high power applications due to their many advantages such as low power dissipation on power switches, low harmonic contents and low electromagnetic interference (EMI) outputs. The selected switching technique to control the inverter will also have an effective role on harmonic elimination while generating the ideal output voltage. Intensive studies have been performed on carrier-based, sinusoidal, space vector and sigma delta PWM methods in open loop control of inverters. The selection of topology and control techniques may vary according to power demands of inverter. This paper and review results constitute a useful basis for matching of inverter topology and the best control scheme according to various application areas.

Colak, Ilhami [Department of Electrical Education, Faculty of Technical Education, Gazi University, Besevler, Ankara 06500 (Turkey); Kabalci, Ersan, E-mail: kabalci@nevsehir.edu.t [Department of Technical Programs, Vocational Collage of Haci Bektas, Nevsehir University, Hacibektas, Nevsehir 50800 (Turkey); Bayindir, Ramazan [Department of Electrical Education, Faculty of Technical Education, Gazi University, Besevler, Ankara 06500 (Turkey)

2011-02-15

126

Review of multilevel voltage source inverter topologies and control schemes

International Nuclear Information System (INIS)

In this study, the most common multilevel inverter topologies and control schemes have been reviewed. Multilevel inverter topologies (MLIs) are increasingly being used in medium and high power applications due to their many advantages such as low power dissipation on power switches, low harmonic contents and low electromagnetic interference (EMI) outputs. The selected switching technique to control the inverter will also have an effective role on harmonic elimination while generating the ideal output voltage. Intensive studies have been performed on carrier-based, sinusoidal, space vector and sigma delta PWM methods in open loop control of inverters. The selection of topology and control techniques may vary according to power demands of inverter. This paper and review results constitute a useful basis for matching of inverter topology and the best control scheme according to various application areas.

127

Mitigation of Lower Order Harmonics with Filtered Svpwm In Multiphase Voltage Source Inverters

Directory of Open Access Journals (Sweden)

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.

K. Uday Kiran

2014-08-01

128

Multilevel cascade voltage source inverter with seperate DC sources

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.

Peng, Fang Zheng (Knoxville, TN); Lai, Jih-Sheng (Blacksburg, VA)

2002-01-01

129

Multilevel cascade voltage source inverter with separate DC sources

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations. 15 figs.

Peng, F.Z.; Lai, J.S.

1997-06-24

130

Power Quality Improvement using Dual Voltage Source Converter Based DVR

Directory of Open Access Journals (Sweden)

Full Text Available In any power system, The modelling and simulation of three and seven-level Dual Voltage Source Converter based dynamic voltage restorer (DVR aimed at correcting the supply voltage sag/swell and interruption in low voltage distribution networks. The proposed design models of DVSC based DVR are expected to be most powerful solutions to minimize supply voltage disturbances of the sensitive loads. A DVR is a VSC based power electronics device connected in series between the supply and the critical loads, which are to be protected from the supply side voltage quality problems, other than outages, by injecting the required compensating voltage through DVR into the distribution line. The proposed models of DVR together with the controllers are simulated by using MAT LAB Simulink and the results are presented to assess the performance of each device.

A.Suresh

2014-01-01

131

High-Speed Fuses in IGBT based Voltage Source Converters

DEFF Research Database (Denmark)

The demand for protection of power electronic applications has during the last couple of years increased regarding the high-power IGBT modules. Even with an active protection, a high power IGBT still has a risk of exhibiting a violent rupture in the case of a fault if IGBT fuses do not protect it. By introducing fuses into voltage source converters a better protection of IGBTs can be achieved. This paper is a complete overview of a research project carried out in cooperation by Aalborg University, Denmark and Cooper Bussmann International. This paper discusses three main issues regarding the IGBT fuse protection. First, the problem of adding inductance in the DC-link circuit is treated, second a short discussion of the protection of the IGBT module is done, and finally, the impact of the high frequency loading on the current carrying capability of the fuses is presented.

Iov, Florin; Blaabjerg, Frede

2005-01-01

132

Low-cost PWM speed controller for an electric mini-baja type vehicle

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...

Samuel Euzédice de Lucena; Márcio Abud Marcelino; Francisco José Grandinetti

2007-01-01

133

DEFF Research Database (Denmark)

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.

Mathe, Laszlo; Cornean, Horia

2011-01-01

134

Performance of voltage source multilevel inverter - fed induction motor drive using Simulink

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...

Neelashetty Kashappa; Ramesh Reddy K.

2011-01-01

135

Performance of voltage source multilevel inverter - fed induction motor drive using Simulink

Directory of Open Access Journals (Sweden)

Full Text Available This paper deals with performance of voltage source multilevel inverter-fed induction motor drive. A Voltage source inverter (VSI is compared with multilevel inverter. A conventional Voltage Source Inverter-fed induction motor drive is modeled and simulated using Matlab/ Simulink and the results are presented. Multilevel inverter employing Selective Harmonic Elimination (SHE method is also simulated and the corresponding results are presented. The FFT spectrum for the outputs is analyzed to study the reduction in harmonics.

Neelashetty Kashappa

2011-06-01

136

Three phase AC motor controller

A motor controller for a three phase AC motor (10) which is adapted to operate bidirectionally from signals received either from a computer (30) or a manual control (32). The controller is comprised of digital logic circuit means which implement a forward and reverse command signal channel (27, 29) for the application of power through the forward and reverse power switching relays (16, 18, 20, 22). The digital logic elements are cross coupled to prevent activation of both channels simultaneously and each includes a plugging circuit (65, 67) for stopping the motor upon the removal of control signal applied to one of the two channels (27, 29) for a direction of rotation desired. Each plugging circuit (65, 67) includes a one-shot pulse signal generator (88, 102) which outputs a single pulse signal of predetermined pulsewidth which is adapted to inhibit further operation of the application of power in the channel which is being activated and to apply a reversal command signal to the other channel which provides a reversed phase application of power to the motor for a period defined by the pulse-width output of the one-shot signal generator to plug the motor (10) which will then be inoperative until another rotational command signal is applied to either of the two channels.

Vuckovich, Michael (Elizabeth, PA); Wright, Maynard K. (Bethel Park, PA); Burkett, John P. (South Huntington Township, Westmoreland County, PA)

1984-03-20

137

Component-Minimized Buck-Boost Voltage Source Inverters

DEFF Research Database (Denmark)

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.

Gao, F.; Loh, P.C.

2007-01-01

138

Directory of Open Access Journals (Sweden)

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.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 second 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.

Robinson F. de Camargo

2004-09-01

139

Modeling and Simulation of DSP Controlled SV PWM Three Phase VSI

Directory of Open Access Journals (Sweden)

Full Text Available The present research is concerned with the development of two space vector pulse width modulated VSI models using the software package Matlab. The theoretical principles underlying the space vector modulation technique are presented but have been limited to the few relations needed for the model implementation. The first model, the formulation of which is based on the concept of switching function associated with the semiconductor power switches, is a switched mode inverter while the second model, the sine mode inverter, is formulated in terms of the duty times cycles of the pole switches is a nearly perfect sine wave space vector controlled generator. By comparison to the switched mode inverter, the sine mode inverter exhibits a larger bandwidth to frequency demand. The reliability of the sine mode model has been checked against the experimental results available in the literature provided by Analog Device Corporation.

A. Saadoun

2007-01-01

140

This paper presents the comparison of Unipolar Inverted Sine Carrier Pulse Width Modulation (UISCPWM) techniques for the Cascaded Multi Level Inverter (CMLI). Due to switch combination redundancies, there are certain degrees of freedom to generate the multilevel AC output voltage. This paper presents the use of Control Freedom Degree (CFD) combination. The effectiveness of the pulse width modulation strategies developed using CFD are demonstrated using simulation. The results indicate that th...

Balamurugan, C. R.; Natarajan, S. P.; Bensraj, R.

2012-01-01

141

Three-phase power supply, output 60v and 100a, with unit power factor and low RFI level

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, ...

João Batista Vieira Júnior; Luiz Carlos de Freitas; Adriano Alves Pereira; Lúcio dos Reis Barbosa; Carlos Henrique Gonçalves Treviso

2003-01-01

142

Developing a voltage-source shunt active power filter for improving power quality

Energy Technology Data Exchange (ETDEWEB)

Active filters are controlled current or voltage sources that can be used, for example, to compensate current harmonics, interharmonics and reactive power. They offer a wide and/or selectable filtering bandwidth and they are small in size. In addition, active filters can solve almost all the problems that exist with conventional passive filters. This thesis is concerned with developing a digitally controlled three-phase voltage-source shunt active power filter. First, the current compensation characteristic of the active power filter is studied and methods to improve this by compensating and minimizing effects caused by control system delays are investigated and proposed. Computational and prediction-based delay compensation methods are presented. Also, two methods in which the effect of the processing delay is eliminated by applying current-sensorless control and modified main circuit structure are proposed. Both the theoretical study and the experimental results presented show that all the studied methods provide effective compensation characteristics. The use of the LCL-type supply filter in an active power filter is studied by comparing an active and a passive resonance damping method and by assessing the suitability of each for the active power filter application. The results presented show that both of the damping methods provide the fast dynamic responses required in using the active power filter as well as efficient current ripple attenuation. In addition, the results obtained show that the passive damping method increases the power losses only slightly. In contrast, the active damping requires several current sensors and more complicated control than the passively damped system. The power loss profile of the active filter is determined and the effect of replacing the antiparallel silicon diodes in the IGBT bridge with their silicon carbide (SiC) counterparts is studied. The calculation and measurement results show that SiC diodes provide a reduction in the semiconductor power losses of the active filter. The reduction is important, since this would make it possible to reduce the cooling or to increase the switching frequency. The higher switching frequency would enable the use of smaller filter chokes. A comparison of the digitally controlled and vector-modulated voltage-source and currentsource active power filters is presented. The main circuit configurations and space-vector modulation techniques used are discussed as well as the load current detection -based control systems. In addition, the filtering characteristics, power loss distributions, and efficiencies of both systems are studied and compared in various operating points. Finally, a case study in which a combined active and passive compensator is applied to mitigate the voltage flicker problem caused by a resistance spot welding process is presented. The compensation characteristic of the solution is considered comprehensively, using simulations and practical measurements. Furthermore, the resulting flicker severity indices are assessed. The results show that the compensator offers a great reduction of the voltage drops causing the flicker. (orig.)

Routimo, M.

2008-07-01

143

Sliding mode Control using 3D-SVM for Three-phase Four-Leg Shunt Active Filter

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 perf...

Bouzidi Mansour; Benaissa Abdelkader; Barkat Said

2013-01-01

144

This paper proposes a system, based on a selfexcited induction generator with a shunt electronic converter, to feed isolated three-phase and single-phase linear or nonlinear loads. The electronic converter is composed by a three-phase four-wire voltage source inverter (VSI) and, connected to its dc side, two dc/dc converters. The VSI compensates the current harmonics, the reactive power and the load unbalances. The first of the dc/dc converters is a battery charger/discharger and the other co...

Barrado Rodrigo, Jose? Antonio; Grin?o? Cubero, Robert; Valderrama Blavi, Hugo

2007-01-01

145

Asymmetrical three-phase induction motor performance through the use of dynamic capacitance witching

Energy Technology Data Exchange (ETDEWEB)

This paper presents a performance analysis for the asymmetrical three-phase induction motor fed by a single phase voltage source. High load diversity can be a constant through the working period of an induction motor. So the switching of capacitance along with load variation is a good strategy to keep the motor asymmetry balanced with the load instantaneous condition. Theoretical results of such switching are presented for a 2 HP asymmetrical induction motor. This analysis allowed us to get satisfactory conclusions on the performance of the asymmetrical motor when applied a dynamic capacitance switching system. (orig.)

Neto, L.M.; Teixcira, H.B.; Camacho, J.R. [Universidade Federal de Uberlandia, School of Electrical Engineering, Uberlandia (Brazil); Mendonca, R.G. de [CEFET-GO - Jatai Decentralized Unity, Electrotechnical Coordination, Jatai (Brazil)

2000-08-01

146

Three-Phase Grid-Connected of Photovoltaic Generator Using Nonlinear Control

DEFF Research Database (Denmark)

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.

Yahya, A.; El Fadil, H.

2014-01-01

147

PERFORMANCE ANALYSIS OF SENSORLESS BLDC MOTOR DRIVE SYSTEM USING ASYMMETRIC PWM CONTROL TECHNIQUE

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...

Meenakshi, R.; Sella Kumar, S.; Sasikumar, Dr M.

2012-01-01

148

PWM Algorithms for Multilevel Inverter Supplied Multiphase Variable-Speed Drives

Multiphase variable speed drives are nowadays regarded as serious contenders for various applications, due to the certain advantages that they possess when compared to threephase drives. On the other hand, the multilevel (predominantly three-level) voltage source inverter (VSI) has become an industrially accepted technology for medium-voltage three-phase drives. The logical next step is to integrate multilevel VSI and multiphase drive technologies, since benefits of each can then be combined....

Martin Jones; Obrad Dordevic; Nandor Bodo; Emil Levi

2012-01-01

149

Shunt active filter algorithms for a three phase system fed to adjustable speed drive

Directory of Open Access Journals (Sweden)

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.

Sujatha.CH

2011-10-01

150

Directory of Open Access Journals (Sweden)

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.

Robinson F. de Camargo

2005-12-01

151

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish 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.

O., Malik; F. J., De la Hidalga-W..

2013-02-01

152

The Investigation of Sinusoidal Single Phase Voltage Source Inverter Output Filter

The results of output filter investigation of single phase sine voltage source inverter (VSI) are presented. The operating principle, construction and a most widely used topology of single phase voltage source inverter is discussed. The results obtained using modeling and experimental investigation are presented. The Total Harmonic Distortion of the inverter output voltage and maximal current of the output capacitor were analyzed using Matlab Simulink software. The 1 kW inverter prototype ...

Andrius Platakis; Vytautas Bleizgys; Tadas Lipinskis

2011-01-01

153

Directory of Open Access Journals (Sweden)

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.

M.NEELU KUMAR, P.BHASKARA PRASAD, PADMA LALITHA

2013-11-01

154

DEFF Research Database (Denmark)

This paper presents detailed description of one-stage and two-stage schemes of a novel method of synchronous, pulsewidth modulation (PWM) for voltage source inverters for ac drive application. The proposed control functions provide accurate realization of different versions of voltage space vector modulation with synchronization of the voltage waveform of the inverter and with smooth pulse-ratio changing. Voltage spectra do not contain even harmonic and sub-harmonics (combined harmonics) during the whole control range including the zone of overmodulation. Examples of determination of the basic control parameters of the inverters with low switching frequency, as wel1 as results of its simulations, are presented.

Oleschuk, V.; Blaabjerg, Frede

2002-01-01

155

International Nuclear Information System (INIS)

This paper presents a new zero voltage transition (ZVT), power factor corrected three phase ac-ac converter with single phase high frequency (HF) link. It is a two stage converter; the first stage is a boost integrated bridge converter (combination of a 3 ph boost converter and a bridge converter) operated at fixed frequency and that operates in two modes at ZVT for all switches and establishes a 1 ph square wave HF link. The second stage is a bi-directional pulse width modulation (PWM) 3 ph bridge that converts the 1 ph HF link to a 3 ph voltage using a novel switching strategy. The converter modes of operation and key equations are outlined. Simulation of the overall system is conducted using Simulink. The switching strategy and its corresponding control circuit are clearly described. Experimental verification of the simulation is conducted for a prototype of 100 V, 500 W at 10 kHz link frequency

156

Energy Technology Data Exchange (ETDEWEB)

This paper presents a new zero voltage transition (ZVT), power factor corrected three phase ac-ac converter with single phase high frequency (HF) link. It is a two stage converter; the first stage is a boost integrated bridge converter (combination of a 3 ph boost converter and a bridge converter) operated at fixed frequency and that operates in two modes at ZVT for all switches and establishes a 1 ph square wave HF link. The second stage is a bi-directional pulse width modulation (PWM) 3 ph bridge that converts the 1 ph HF link to a 3 ph voltage using a novel switching strategy. The converter modes of operation and key equations are outlined. Simulation of the overall system is conducted using Simulink. The switching strategy and its corresponding control circuit are clearly described. Experimental verification of the simulation is conducted for a prototype of 100 V, 500 W at 10 kHz link frequency. (author)

Abdelhamid, Tamer H.; Sabzali, Ahmad J. [Electrical Engineering Department, College of Technological Studies (Kuwait)

2008-05-15

157

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)

158

CONCEPTUAL THREE PHASE ITERATIVE MODEL OF KDD

Directory of Open Access Journals (Sweden)

Full Text Available KDD process includes how data is stored and accessed, how andwhat algorithms can apply to large amount of data efficiently,how results can be interpreted and visualized. KDD is theprocess of identifying valid, interesting and understandablepatterns in data. In this paper we will describe conceptual threePhase Iterative Model of KDD. The main layers of this purposedmodel are: Philosophy Layer, Technique Layer and ApplicationLayer. We will also perform the comparison of Tradition KDDModel with Three Phase Iterative Model.

Simmi Bagga

2012-02-01

159

A Transformerless Hybrid Filter Using a Three-Level Diode-Clamped PWM Converter

This paper deals with a transformerless hybrid active filter integrated into a medium-voltage three-phase diode rectifier used as the front end of an adjustable-speed motor drive. The hybrid filter is formed by a single LC filter tuned to the 7th-harmonic frequency per phase and a small-rated active filter based on a three-phase three-level diode-clamped PWM converter. A three-phase downscaled system rated at 400V and 15kW is designed, constructed, and tested to verify the filtering performance of the hybrid filter. Experimental results show that the current THD (total harmonic distortion) gets less than 5%, and that the voltage-balancing control proposed in this paper works properly even in transient states.

Hatada, Takaaki; Akagi, Hirofumi

160

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...

Rathika, P.; Devaraj, D.

2011-01-01

161

Assessment of the impact that individual voltage source has on a generator’s stability

DEFF Research Database (Denmark)

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.

Dmitrova, Evgeniya; Jóhannsson, Hjörtur

2012-01-01

162

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.

163

Low-cost PWM speed controller for an electric mini-baja type vehicle

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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.

Samuel Euzédice de, Lucena; Márcio Abud, Marcelino; Francisco José, Grandinetti.

2007-03-01

164

Low-cost PWM speed controller for an electric mini-baja type vehicle

Directory of Open Access Journals (Sweden)

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.

Samuel Euzédice de Lucena

2007-03-01

165

A Single Phase to Three Phase PFC Half-Bridge Converter Using BLDC Drive with SPWM Technique.

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...

Srinu Duvvada; Manmadha Kumar B

2014-01-01

166

The overview of damping methods for three-phase grid-tied inverter with LLCL-filter

DEFF Research Database (Denmark)

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.

Huang, Min; Blaabjerg, Frede

2014-01-01

167

Sliding mode Control using 3D-SVM for Three-phase Four-Leg Shunt Active Filter

Directory of Open Access Journals (Sweden)

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.

Bouzidi Mansour

2013-02-01

168

Directory of Open Access Journals (Sweden)

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 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 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.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 specification 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.

Leandro Michels

2005-06-01

169

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese 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.

Leandro, Michels; Robinson F. de, Camargo; Fernando, Botterón; Humberto, Pinheiro.

2005-06-01

170

Methods, systems and apparatus for adjusting duty cycle of pulse width modulated (PWM) waveforms

Embodiments of the present invention relate to methods, systems and apparatus for controlling operation of a multi-phase machine in a vector controlled motor drive system when the multi-phase machine operates in an overmodulation region. The disclosed embodiments provide a mechanism for adjusting a duty cycle of PWM waveforms so that the correct phase voltage command signals are applied at the angle transitions. This can reduce variations/errors in the phase voltage command signals applied to the multi-phase machine so that phase current may be properly regulated thus reducing current/torque oscillation, which can in turn improve machine efficiency and performance, as well as utilization of the DC voltage source.

Gallegos-Lopez, Gabriel; Kinoshita, Michael H; Ransom, Ray M; Perisic, Milun

2013-05-21

171

Comparative Analysis of Three Topologies of Three-Phase Five Level Inverter

Directory of Open Access Journals (Sweden)

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.

H. S. Sangolkar, P. A. Salodkar

2014-06-01

172

Performance Evaluation of Three Phase Bridge Module Type Diode Clamped Multilevel Inverter

Directory of Open Access Journals (Sweden)

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.

C.R. Balamurugan, S. P. Natarajan, R.Bensraj

2012-06-01

173

Three-phase fractionation of polydisperse fluids

It is shown that the van der Waals free-energy of polydisperse fluids, as introduced previously (L. Bellier-Castella, H. Xu and M. Baus, {J. Chem. Phys.} {113}, 8337 (2000)), predicts that for certain thermodynamic states (e.g. low temperatures and large polydispersities) the ordinary two-phase coexistences become metastable relative to a fractionation of the system into three phases, reducing thereby the polydispersity of each of the coexisting phases.

Bellier-Castella, L; Xu, H

2001-01-01

174

Three-Phase Shunt Active Power Filter

Active power filters have been widely used for harmonic elimination. The performance of a conventional three-phase shunt Active Power Filter (APF) using Synchronous Detection Method (SDM) has been compared with Nonlinear Autoregressive-Moving Average (NARMA)-L2 based APF. The novelty of this study lies in the application of NARMA-L2 control to generate the amplitude of the reference supply current required by the APF circuit and the successful implementation of the APF system for harmonic eli...

Moleykutty George; Basu, Kartik P.

2008-01-01

175

UNIVERSAL THREE-PHASE FERRORESONANCE STABILIZERS

A comparative analysis has been carried out on two options of three-phase parametric current sources (inductive-capacitive stabilizers). Their capacities to operate in voltage stabilizer mode have been studied. Such capacities were proven and their conditions were defined. Theoretical results were experimentally checked and confirmed with satisfactory accuracy. Based on theoretical and experimental studies it was proven that the considered systems can operate in both modes-as current and volt...

GEORGI GEORGIEV; NADEZHDA EVSTATIEVA

2013-01-01

176

UNIVERSAL THREE-PHASE FERRORESONANCE STABILIZERS

Directory of Open Access Journals (Sweden)

Full Text Available A comparative analysis has been carried out on two options of three-phase parametric current sources (inductive-capacitive stabilizers. Their capacities to operate in voltage stabilizer mode have been studied. Such capacities were proven and their conditions were defined. Theoretical results were experimentally checked and confirmed with satisfactory accuracy. Based on theoretical and experimental studies it was proven that the considered systems can operate in both modes-as current and voltage stabilizers.

GEORGI GEORGIEV

2013-03-01

177

Indirect current control with separate IZ drop compensation for voltage source converters

Energy Technology Data Exchange (ETDEWEB)

Indirect Current Control (ICC) of boost type Voltage Source Converters (VSCs) using separate compensation of line IZ voltage drop is presented. A separate bi-directional VSC is used to produce the compensation voltage. This simplifies the ICC regulator scheme as the power flow is controlled through single modulation index. Experimental verification is provided for bi-directional control of the power flow.

Kanetkar, V.R. [Asea Brown Boveri Ltd., Vadodara (India). Corporate R and D; Dawande, M.S. [R.K.N. Engineering Coll., Nagpur (India). Dept. of Electrical Engineering; Dubey, G.K. [Indian Inst. of Tech., Kanpur (India). Dept. of Electrical Engineering

1995-12-31

178

Analisis Harmonisa Inverter PWM Satu Fasa

Pada tesis ini dianalisis harmonisa inverter PWM satu fasa. Inverter PWM satu fasa yang akan ditinjau adalah inverter satu fasa jembatan penuh (konvensional) dan inverter komposit. Analisis difokuskan pada penentuan pola penyaklaran yang optimum agar pembangkitan harmonisa dan switching losses inverter rendah. Untuk menentukan pola penyaklaran optimum maka dilakukan analisis yang berbasis pada rangkaian ekivalen harmonisa inverter satu fasa. Dengan menggunakan pola penyaklaran optimum, kedua ...

Rejeki Simanjorang

2008-01-01

179

Directory of Open Access Journals (Sweden)

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.

Chandra Babu Paduchuri

2014-01-01

180

Directory of Open Access Journals (Sweden)

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.

B. Santhosh Kumar

2014-02-01

181

Three phase full wave dc motor decoder

A three phase decoder for dc motors is disclosed which employs an extremely simple six transistor circuit to derive six properly phased output signals for fullwave operation of dc motors. Six decoding transistors are coupled at their base-emitter junctions across a resistor network arranged in a delta configuration. Each point of the delta configuration is coupled to one of three position sensors which sense the rotational position of the motor. A second embodiment of the invention is disclosed in which photo-optical isolators are used in place of the decoding transistors.

Studer, P. A. (inventor)

1977-01-01

182

The Investigation of Sinusoidal Single Phase Voltage Source Inverter Output Filter

Directory of Open Access Journals (Sweden)

Full Text Available The results of output filter investigation of single phase sine voltage source inverter (VSI are presented. The operating principle, construction and a most widely used topology of single phase voltage source inverter is discussed. The results obtained using modeling and experimental investigation are presented. The Total Harmonic Distortion of the inverter output voltage and maximal current of the output capacitor were analyzed using Matlab Simulink software. The 1 kW inverter prototype was built for experimental investigation. The inverter switches are realized using IGBT transistors. The toroidal iron powder core with distributed air gap was used as the core of the inductor. The experimental investigation of inductor core losses and maximal current of output filter capacitor were performed.Article in Lithuanian

Andrius Platakis

2011-08-01

183

Voltage Source Inverter/Converter for the Improvement of Power Quality Using Fuzzy Logic Controller

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...

Jagan Mohan Rao, T.; Anil Kumar, P.

2014-01-01

184

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 ...

Javad Faiz; Ghazanfar Shahgholian; Mehdi Ehsan

2011-01-01

185

Selective Harmonic Virtual Impedance for Voltage Source Inverters with LCL filter in Microgrids

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...

Savaghebi, Mehdi; Vasquez, Juan Carlos; Jalilian, Alireza Jalilian; Guerrero, Josep M.; Lee, Tzung-lin

2012-01-01

186

MODELING AND SIMULATION OF A NOVEL SERIES/PARALLEL VOLTAGE SOURCES MULTILEVEL INVERTER

In this paper, a new topology of cascaded multilevel inverter with a high number of steps associated with a low number of switches is presented. A multilevel voltage is obtained by cascading two H-bridges and an inverter. Voltage sources are connected in series/parallel by the switching devices. The size, complexity and power consumption in the gate driving circuits is also reduced. Reduction of rating of the switches is another advantage. The total harmonic distortion (THD) is reduced with m...

N.SANTHOSH SINGH.B,; Brahmaiah, Dr B.

2011-01-01

187

Cross connected multilevel voltage source inverter topologies for medium voltage applications

Multilevel voltage source inverters where first introduced in the early 1980s. Since then, they have been continuously developed, offering a wide new research area in power electronics. The popularity of multilevel solutions come from the advantages that they offer: improved output quality, voltage sharing in high voltage applications, increased power density or reduction of filtering costs. Two completely new and innovative cross-connected topological families for advanced multilevel voltage...

Chaudhuri, Toufann

2008-01-01

188

The Initial Parameters Design of the Voltage Source Converter Fed SMES

Directory of Open Access Journals (Sweden)

Full Text Available The initial parameters of the superconducting magnetic energy storage (SMES fed by a voltage source converter (VSMES are studied and the setting rules are designed in this paper. A time-domain simulation model is established by using the software PSCAD/EMTDC. Based on this model, the application of the VSMES in the power system is used to test the designed rules. The simulation results are valuable for the further research of the initial parameters design of the VSMES.

Xudong Song

2010-08-01

189

The Initial Parameters Design of the Voltage Source Converter Fed SMES

The initial parameters of the superconducting magnetic energy storage (SMES) fed by a voltage source converter (VSMES) are studied and the setting rules are designed in this paper. A time-domain simulation model is established by using the software PSCAD/EMTDC. Based on this model, the application of the VSMES in the power system is used to test the designed rules. The simulation results are valuable for the further research of the initial parameters design of the VSMES.

Xudong Song; Zhi Xu; Tieyuan Xiang

2010-01-01

190

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...

Rabie, Amiri; Karim, Fellah Mohammed; Samir, Hadjeri; Ahmed, Zidi Sid; Mohamed, Khatir

2009-01-01

191

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 t...

Tian Yizhi; Chao Qin

2013-01-01

192

A low-power circuit for piezoelectric vibration control by synchronized switching on voltage sources

In the paper, a vibration damping system powered by harvested energy with implementation of the so-called SSDV (synchronized switch damping on voltage source) technique is designed and investigated. In the semi-passive approach, the piezoelectric element is intermittently switched from open-circuit to specific impedance synchronously with the structural vibration. Due to this switching procedure, a phase difference appears between the strain induced by vibration and the resu...

Shen, Hui; Qiu, Jinhao; Ji, Hongli; Zhu, Kongjun; Balsi, Marco; Giorgio, Ivan; Isola, Francesco

2010-01-01

193

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.

194

Variable speed wind turbine generator system with current controlled voltage source inverter

Energy Technology Data Exchange (ETDEWEB)

highlights: {yields} Current controlled voltage source inverter scheme for wind power application. {yields} Low voltage ride through of wind farm. {yields} 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 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.

Muyeen, S.M., E-mail: muyeen0809@yahoo.co [Dept. of Electrical Engineering, Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Al-Durra, Ahmed [Dept. of Electrical Engineering, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Tamura, J. [Dept. of EEE, Kitami Institute of Technology, 165 Koen-cho, Kitami 090-8507 (Japan)

2011-07-15

195

Three-Phase Shunt Active Power Filter

Directory of Open Access Journals (Sweden)

Full Text Available Active power filters have been widely used for harmonic elimination. The performance of a conventional three-phase shunt Active Power Filter (APF using Synchronous Detection Method (SDM has been compared with Nonlinear Autoregressive-Moving Average (NARMA-L2 based APF. The novelty of this study lies in the application of NARMA-L2 control to generate the amplitude of the reference supply current required by the APF circuit and the successful implementation of the APF system for harmonic elimination. The entire system has been modeled using MATLAB 6.1 toolbox. Simulation results demonstrate the applicability of NARMA-L2 controller for the control of APF.

Moleykutty George

2008-01-01

196

Three Phase Active Conditioner for Harmonics Mitigation

Directory of Open Access Journals (Sweden)

Full Text Available The Shunt Active Power Filter is a very essential tool to remove harmonic currents and to reimburse reactive power for nonlinear loads. The fundamental standard of process of a Shunt Active Power Filter is to introduce an appropriate non-sinusoidal current (compensating current into the system at the point of common coupling. This research work focuses on the time-domain approach for three-phase Shunt Active Power Filters through an effective algorithm. A fundamental outline and evaluation of the performance of existing improved algorithms for active power filters are presented. An enhanced approach based on time domain technique is proposed based on various complicated power quality problems and various compensation functions. It is observed that the proposed algorithm provides has shorter response time delay when compared with the conventional approaches. Therefore, the proposed approach can accurately attain various compensating current references.

P.M. Balasubramaniam

2012-09-01

197

Cascaded Multilevel Inverter with PWM Control Method

Directory of Open Access Journals (Sweden)

Full Text Available A hybrid cascaded multilevel inverter with PWM method is presented in this paper. It consists of a standard 3-leg inverter (one leg for each phase and Hbridge in series with each inverter leg. It can use only a single DC power source to supply a standard 3-leg inverter along with three full H-bridges supplied by capacitors. Multilevel carrier- based PWM method is used to produce a five-level phase voltage. The inverter can be used in hybrid electric vehicles (HEV and electric vehicles (EV. A simulation model based on PSIM and MATLAB/SIMULINK is developed. An experimental 5 kW prototype inverter is built and tested. The results experimentally validate the proposed PWM hybrid cascaded multilevel inverter.

M.Kiran Kumar #1 , M.Saikiran *2 , Ch.Venkateswarlu

2013-05-01

198

PWM inverter system for wind power generators

Energy Technology Data Exchange (ETDEWEB)

This paper reports on an experiment on PWM (Pulse Width Modulation) converter to be used for Tokai Wind Turbines. This generating system, firstly stores direct current in a storage battery by wind turbine generators, then converts the direct current into the alternating current by the PWM inverter, and supply it for the individual load. In this experiment a GTO (Gate Turn Off) thyrister was used to construct a PWM inverter system. The GTO used is GFT 50B12 suppled by Hitachi, Ltd. with rated output voltage 100 V and output current 5 A. Results of experiments shows that: 1. A sinusoidal A.C. with high accuracy could be obtained even in a small output D.C. voltage. 2. Conversion efficiency was approximately 75 - 85 %. (6 figs, 6 refs)

Okabe, Takatsugu; Mizutani, Yoshibumi

1987-03-20

199

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)

200

PWM Switching Strategy for Torque Ripple Minimization in BLDC Motor

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.

Salah, Wael A.; Ishak, Dahaman; Hammadi, Khaleel J.

2011-05-01

201

Cascaded Multilevel Inverter with PWM Control Method

A hybrid cascaded multilevel inverter with PWM method is presented in this paper. It consists of a standard 3-leg inverter (one leg for each phase) and Hbridge in series with each inverter leg. It can use only a single DC power source to supply a standard 3-leg inverter along with three full H-bridges supplied by capacitors. Multilevel carrier- based PWM method is used to produce a five-level phase voltage. The inverter can be used in hybrid electric vehicles (HEV) and electric vehicles (EV)....

M Kiran Kumar, M. Saikiran

2013-01-01

202

Directory of Open Access Journals (Sweden)

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.

Javad Faiz

2011-01-01

203

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish 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.

C, Núñez-Gutiérrez; J, Lira-Pérez; V.M., Cárdenas-Galindo; R, Alvarez-Salas.

2009-03-01

204

System For Characterizing Three-Phase Brushless dc Motors

System of electronic hardware and software developed to automate measurements and calculations needed to characterize electromechanical performances of three-phase brushless dc motors, associated shaft-angle sensors needed for commutation, and associated brushless tachometers. System quickly takes measurements on all three phases of motor, tachometer, and shaft-angle sensor simultaneously and processes measurements into performance data. Also useful in development and testing of motors with not only three phases but also two, four, or more phases.

Howard, David E.; Smith, Dennis A.

1996-01-01

205

A Three-Phase Dual-Input Matrix Converter for Grid Integration of Two AC Type Energy Resources

DEFF Research Database (Denmark)

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.

Liu, Xiong; Wang, Peng

2013-01-01

206

Directory of Open Access Journals (Sweden)

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.

P.Narasimhulu

2014-09-01

207

Directory of Open Access Journals (Sweden)

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.

SAFDAR FASAL T K, UNNIKRISHNAN L

2013-07-01

208

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese 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.

Ricardo Q., Machado; Amílcar F. Q., Gonçalves; Simone, Buso; José A., Pomilio.

2009-09-01

209

Directory of Open Access Journals (Sweden)

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.

Ricardo Q. Machado

2009-09-01

210

Directory of Open Access Journals (Sweden)

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.

Tian Yizhi

2013-01-01

211

Selective Harmonic Virtual Impedance for Voltage Source Inverters with LCL filter in Microgrids

DEFF Research Database (Denmark)

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.

Savaghebi, Mehdi; Vasquez, Juan Carlos

2012-01-01

212

MODELING AND SIMULATION OF A NOVEL SERIES/PARALLEL VOLTAGE SOURCES MULTILEVEL INVERTER

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, a new topology of cascaded multilevel inverter with a high number of steps associated with a low number of switches is presented. A multilevel voltage is obtained by cascading two H-bridges and an inverter. Voltage sources are connected in series/parallel by the switching devices. The size, complexity and power consumption in the gate driving circuits is also reduced. Reduction of rating of the switches is another advantage. The total harmonic distortion (THD is reduced with more number of steps in output voltage without using pulse width modulation techniques. The proposed setup configures theoretical approach along with simulations carried on MATLAB/SIMULINK environment. Simulation results are shown and compared with theoretical results.

N.SANTHOSH SINGH.B,

2011-06-01

213

This paper investigates advantages of new combination of the induction generator for wind power and the power electronic equipment. Induction generator is popularly used for the wind power generation. The disadvantage of it is impossible to generate power at the lower rotor speed than the synchronous speed. To compensate this disadvantage, expensive synchronous generator with the permanent magnets is sometimes used. In proposed scheme, the diode rectifier is used to convert the real power from the induction generator to the intermediate dc voltage, while only the reactive power necessary to excite the induction generator is supplied from the voltage source converter (VSC). This means that the rating of the expensive VSC is minimized and total cost of the wind power generation system is decreased compared to the system with synchronous generator. Simulation study to investigate the control strategy of proposed system is performed. The results show the reduction of the VSC rating is prospective.

Morizane, Toshimitsu; Kimura, Noriyuki; Taniguchi, Katsunori

214

Estimation of the Plant Time Constant of Current-Controlled Voltage Source Converters

DEFF Research Database (Denmark)

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.

Vidal, Ana; Yepes, Alejandro G.

2014-01-01

215

Three phase power conversion system for utility interconnected PV applications

Omnion Power Engineering Corporation has developed a new three phase inverter that improves the cost, reliability, and performance of three phase utility interconnected photovoltaic inverters. The inverter uses a new, high manufacturing volume IGBT bridge that has better thermal performance than previous designs. A custom easily manufactured enclosure was designed. Controls were simplified to increase reliability while maintaining important user features.

Porter, David G.

1999-03-01

216

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, the four-leg voltage source converter (VSC with capacitor in its parallel, was functioned as a distribution static compensator (DSTATCOM. In three-phase four-wire distribution system, DSTATCOM was proposed for obtaining load balancing, harmonic current reduction and voltage regulation. The proposed technology was based on synchronous reference frame (SRF Theory. This theory was used for generating a reference current or gate pulse for VSC of DSTATCOM. Performance analysis of DSTATCOM under linear non linear loads was carried out and the Simulink results were shown. The analysis was carried out in MATLAB environment using Simulink and SimPowerSystem toolbox. The proposed SRF based DSTATCOM model was seen to be very effective to enhance the power quality of a three phase four wire distribution system.

Juhi Choudhary*

2014-12-01

217

An improved fault-tolerant control scheme for PWM inverter-fed induction motor-based EVs.

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

Tabbache, Bekheïra; Benbouzid, Mohamed; Kheloui, Abdelaziz; Bourgeot, Jean-Matthieu; Mamoune, Abdeslam

2013-11-01

218

PERFORMANCE ANALYSIS OF SENSORLESS BLDC MOTOR DRIVE SYSTEM USING ASYMMETRIC PWM CONTROL TECHNIQUE

Directory of Open Access Journals (Sweden)

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.

R.Meenakshi

2012-05-01

219

Z-source inverter with a new space vector PWM algorithm for high voltage gain

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a methodology to apply a novel space vector pulse width modulation control for three phase Z-source inverter. The space vector modulation for the conventional voltage source inverter is modified so that the additional shoot-through states are inserted within the zero states. So zero voltage time period is diminished for generating a shoot-through time, and active states are unchanged. The shoot-through states are evenly distributed to each phase within zero state. The shoot-through time is used for controlling the dc link voltage boost and hence the output voltage boost of the inverter. This new method provides a high voltage gain at higher modulation index. The proposed algorithm is verified with simulation and experiment. MatLab/Simulink is used for simulating the complete circuit with RL load. The frequency spectra of the output voltage and current are explored.

U. Shajith Ali

2011-06-01

220

Matlab/Simulink Based Analysis of Voltage Source Inverter With Space Vector Modulation

Space vector modulation (SVM) is the best modulation technique to drive 3-phase load such as 3-phase induction motor. In this paper, the pulse width modulation strategy with SVM is analyzed in detail. The modulation strategy uses switching time calculator to calculate the timing of voltage vector applied to the three-phase balanced-load. The principle of the space vector modulation strategy is performed using Matlab/Simulink. The simulation result indicates that this algorithm is flexible and...

Auzani Jidin; Tole Sutikno

2009-01-01

221

Self oscillating PWM modulators, a topological comparison

DEFF Research Database (Denmark)

High precision control of the output voltage or current of a switch mode converter with fast response is required for a number of applications. Dependent on the type of application, the desired precision and transient response can be difficult, if not impossible, to achieve with standard PWM control caused by limitations in dynamic capabilities which often limits fast tracking of a reference signal, or fast settling during load steps due to too small achievable control loop bandwidth. Achievable open loop bandwidth for standard voltage and current mode PWM modulators is typical in the fs/10 or fs/ð range respectively, where fs is the switching frequency of the converter. For some applications this will require unacceptable high switching frequency to achieve enough control loop bandwidth for the desired dynamic performance. With self oscillating modulators, the open loop bandwidth is equal to fs which makes this type of modulators an excellent choice for a wide range of applications. Self oscillating PWM modulators can be made in a number of ways, either as voltage or current mode modulators, and the self oscillating behavior can be achieved either by using hysteresis control or by shaping the open loop function of the modulator so its gain and phase response causes a closed loop natural oscillation. The two main types of self oscillating modulators have many similarities, but differences in dynamic performance and linearity are present. The work presented is related to the author's work with switch mode audio power amplifiers, where linear tracking of the reference signal is of major importance. Use of the modulator topologies presented are not limited to this kind of equipment, but can be used in a very wide range of applications from very low to very high power levels.

Poulsen, SØren; Andersen, Michael Andreas E.

2004-01-01

222

Harmonic Filtering Performance of a Hybrid Active Filter for a Three-Phase 12-Pulse Diode Rectifier

This paper describes a hybrid active filter for harmonic-current compensation of a three-phase 12-pulse diode rectifier used as the front end of a medium-voltage motor drive system. This hybrid filter is characterized by the direct series connection of a simple LC filter and a small-rated active filter. This circuit configuration brings low cost, small size, and light weight to the hybrid filter. The authors design, construct, and test a three-phase experimental system rated at 400V and 15kW, which is a downscaled model of the medium-voltage motor drive system. In this experiment, the LC filter is tuned to the 11th harmonic frequency, and the active filter is based on a three-level diode-clamped PWM converter with a dc capacitor voltage as low as 28V. This hybrid filter is connected on either the first or fourth winding of a line-frequency transformer with a first ?-winding voltage of 400V in the primary, and a second ?-winding voltage of 220V, a third Y-winding voltage of 220V, and a fourth ?-winding voltage of 400V in the secondary. Experimental results show that the hybrid filter performs satisfactory filtering in a range from the no-load to full-load conditions.

Isozaki, Kohei; Akagi, Hirofumi

223

7 CFR 3403.4 - Three-phase program.

...Continued) COOPERATIVE STATE RESEARCH, EDUCATION...DEPARTMENT OF AGRICULTURE SMALL BUSINESS INNOVATION RESEARCH...Three-phase program. The Small Business Innovation Research...of performance of the small business concern with a...

2010-01-01

224

Power angle control of grid-connected voltage source converter in a wind energy application

Energy Technology Data Exchange (ETDEWEB)

In this thesis, the connection of a voltage source converter to the grid in a wind energy application is examined. The possibility of using a cheap control system without grid current measurements, is investigated. The control method is based on controlling the voltage angle of the inverter, which governs the active power flow. The highest frequency of the power variation, coming from wind turbine, is approx. 5 Hz. Since the proposed control method easily can handle such power variations it is very well suited for wind turbine applications. The characteristics of the system depend on the DC-link capacitor, the grid filter inductance and resistance. Large values of the resistance damp the system well but increase the energy losses. A high inductance leads to a reduced harmonic level on the grid but makes the system slower. By using feed-forward of the generator/rectifier current signal, the performance is increased compared to an ordinary PI-control. Combining the Linear Quadratic (LQ) control method with Kalman filtered input signals, a robust control method with a good performance is obtained. The LQ controller controls both the phase displacement angle and the modulation index, resulting in higher bandwidth, and the typical power angle resonance at the grid frequency disappears. 22 refs, 109 figs, 14 tabs

Svensson, Jan [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

1995-12-31

225

We propose a novel inverter that can be operated either as a Current Source Inverter (CSI) or as a Voltage Source Inverter (VSI) by changing only the control signals. It is proper to apply it to the interconnecting system with renewal energy, such as photovoltaic cells or wind generation systems, to a grid. This inverter is usually operated as the CSI connected to the grid. Even if the energy source has a lower voltage than the grid, the energy can be supplied to the grid through the proposed inverter. The power factor can be briefly maintained at almost unity. When power supply from the grid is interrupted, the proposed circuit should be operated as the VSI in the stand-alone operation mode. In this way, the circuit can maintain a constant output voltage to the loads. In this paper, the proposed circuit configuration and the control schemes for both the CSI and the VSI are described. Further, the circuit characteristics for both are discussed experimentally.

Teruya, Daisuke; Masukawa, Shigeo; Iida, Shoji

226

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

Dai, NingYi; Lam, Chi-Seng; Zhang, WenChen

2014-01-01

227

This paper presents a medium-voltage motor drive with a three-phase modular multilevel PWM inverter and focuses on its control method and operating performance. This motor drive is particularly suitable for fans, blowers, pumps, and compressors, in which the load torque is proportional to the square of the rotating speed. Particular attention is paid to the dc-capacitor voltage fluctuation of each chopper-cell because it may affect the voltage rating of the power switching devices used. This paper describes the theoretical equations related to the amount of the voltage fluctuation. A downscaled model rated at 400V and 15kW is designed and built to confirm the validity and effectiveness of the nine-level (17-level in line-to-line) PWM inverter that is intended for use in medium-voltage motor drives to achieve energy savings.

Hagiwara, Makoto; Nishimura, Kazutoshi; Akagi, Hirofumi

228

Single-Chip Microcomputer Control Of The PWM Inverter

A single-chip microcomputer-based con-troller for a pulsewidth modulated 1.7 KVA inverter of an airconditioner is presented. The PWM pattern generation and the system control of the airconditioner are achieved by software of the 8-bit single-chip micro-computer. The single-chip microcomputer has the disadvantages of low processing speed and small memory capacity which can be overcome by the magnetic flux control method. The PWM pattern is generated every 90 psec. The memory capacity of the PWM look-up table is less than 2 kbytes. The simple and reliable control is realized by the software-based implementation.

Morimoto, Masayuki; Sato, Shinji; Sumito, Kiyotaka; Oshitani, Katsumi

1987-10-01

229

Three-phase relative permeability of Asphalt Ridge tar sand

Energy Technology Data Exchange (ETDEWEB)

Two-phase relative permeabilities for Asphalt Ridge tar sand have been measured at 350/degree/F (177/degree/C). This temperature was chosen to obtain data appropriate for simulating high temperature operation. A modified equation of Stone (1973) was then used to calculate three-phase relative permeability from the measured two-phase relative permeability data. The measured two-phase relative permeability data show lower values than were predicted using typical tar sand properties. The estimated three-phase relative permeability values calculated from the measured two-phase data are lower than those values determined from estimated two-phase values. Simulations of the wet-forward tar sand combustion model, using the new three-phase relative permeability values, were compared with previous simulations and experimental data. The new three-phase relative permeability values improved the model's ability to predict experimental results. More experimental data, using three-phase relative permeability at different temperatures, may further improve model results. 5 refs., 18 figs., 5 tabs.

Sullivan, S.; Vaughn, P.

1988-08-01

230

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

231

A Composite PWM Control Strategy for Boost Converter

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.

Qingfeng, Liu; Zhaoxia, Leng; Jinkun, Sun; Huamin, Wang

232

Adaptive Harmonic Elimination Technique in Single Phase PWM Inverters

High frequency PWM inverters produce an output voltage spectrum at the fundamental reference frequency and around the switching frequency. Thus ideally PWM inverters do not introduce any significant lower order harmonics. However, in real systems, due to dead-time effect, device drops and other non-idealities lower order harmonics are present. In order to attenuate these lower order harmonics and hence to improve the quality of output current, this paper presents an \\emph{adaptive harmonic e...

Kulkarni, Abhijit; John, Vinod

2011-01-01

233

This study presents a shunt-Connected Voltage Source Convertor (VSC) to mitigate balanced and unbalanced voltage sag and regulate the grid voltage at a fixed level by inserting required reactive power at the Point of Common Coupling (PCC). Moreover, an inner Vector Current-Controller (VCC) and outer voltage controller (VVC) are applied together to calculates the current references for the VCC. Furthermore, an inductor/ capacitor/inductor (LCL) filter is replaced with the simple L-filter in be...

Abdollah Shokri; Hussain Shareef; Azah Mohamed; Shervin Shokri

2013-01-01

234

This paper presents a structured development of a compound state space model of an inverter driven power grid. It allows to perform stability investigations on power grids, depending on the inverter parameters influencing their dynamich behavior and on the grid structure. The general approach is to separate the active components, i.e. the inverters, from the passive components, i.e. the grid, and model them separately. A state space model of a single voltage source inverter is developed and t...

Jostock, Markus; Sachau, Ju?rgen

2012-01-01

235

Matlab/Simulink Based Analysis of Voltage Source Inverter With Space Vector Modulation

Directory of Open Access Journals (Sweden)

Full Text Available Space vector modulation (SVM is the best modulation technique to drive 3-phase load such as 3-phase induction motor. In this paper, the pulse width modulation strategy with SVM is analyzed in detail. The modulation strategy uses switching time calculator to calculate the timing of voltage vector applied to the three-phase balanced-load. The principle of the space vector modulation strategy is performed using Matlab/Simulink. The simulation result indicates that this algorithm is flexible and suitable to use for advance vector control. The strategy of the switching minimizes the distortion of load current as well as loss due to minimize number of commutations in the inverter.

Auzani Jidin

2009-04-01

236

Three-Phase Flow and Capillarity in Porous Media

Energy Technology Data Exchange (ETDEWEB)

Multiphase flow occurs in most production operations on the reservoir rock of an oil field. Three-phase flow occurs in many oil recovery processes, such as gas or water alternating gas injection into water flooded reservoirs, thermal oil recovery and surfactant flooding. In this doctoral thesis, three-phase flow in porous media is modeled using the method of characteristics and simple wave theory. The general mathematical methods are used to model different flow processes: secondary migration of hydrocarbons, gravity segregated three-phase flow, and displacement experiments for relative permeabilities. The main conclusions from applying the methods to the migration process through a water-saturated carrier bed to a partially permeable seal are: (1) the three-phase solutions are generally dominated by the very low gas viscosity and gas density, (2) countercurrent flow and interference between the gas and oil mobilities can lead to trapping in situations where the permeability contrast between the seal and the carrier bed is insufficient to trap oil alone, (3) zones in which pressures exceed those from hydrostatic gradients (overpressured zones) exist even when the permeability contrast between the seal and the carrier bed is modest. The discussion of gravity segregated flow identifies stable displacement fronts, which usually occur only for a single value of the gas-water injection ratio. The new method developed for interpreting displacement experiments, with capillary pressure included, is based on the travelling wave solution of the flow equations. 185 refs., 69 figs., 5 tabs.

Helset, H.M.

1996-06-01

237

A cascaded three-phase symmetrical multistage voltage multiplier

International Nuclear Information System (INIS)

A cascaded three-phase symmetrical multistage Cockcroft-Walton voltage multiplier (CW-VM) is proposed in this report. It consists of three single-phase symmetrical voltage multipliers, which are connected in series at their smoothing columns like string of batteries and are driven by three-phase ac power source. The smoothing column of each voltage multiplier is charged twice every cycle independently by respective oscillating columns and discharged in series through load. The charging discharging process completes six times a cycle and therefore the output voltage ripple's frequency is of sixth order of the drive signal frequency. Thus the proposed approach eliminates the first five harmonic components of load generated voltage ripples and sixth harmonic is the major ripple component. The proposed cascaded three-phase symmetrical voltage multiplier has less than half the voltage ripple, and three times larger output voltage and output power than the conventional single-phase symmetrical CW-VM. Experimental and simulation results of the laboratory prototype are given to show the feasibility of proposed cascaded three-phase symmetrical CW-VM

238

Three phase partitioning for extraction of oil from soybean.

Three phase partitioning, a method generally used for protein separation, has been evaluated for extraction of oil from soybean. 82% oil was extracted within 1 h using this process which required simultaneous addition of t-butanol (1:1, v/v) and 30% ammonium sulphate to the soybean slurry. PMID:12365503

Sharma, Aparna; Khare, S K; Gupta, Munishwar N

2002-12-01

239

Controlling An Inverter-Driven Three-Phase Motor

Control system for three-phase permanent-magnet motor driven by linecommutated inverter uses signals generated by integrating back emf of each phase of motor. High-pass filter network eliminates low-frequency components from control loop while maintaining desired power factor.

Dolland, C.

1984-01-01

240

Hepatic abscess : three-phase helical CT appearance

International Nuclear Information System (INIS)

The purpose of this study was to evaluate the enhancement patterns and morphologic features of hepatic abscesses, as seen on three-phase helical CT images. Three-phase helical CT images of 22 clinically and pathologically proven hepatic abscesses more than 3 cm in diameter in 21 patients were retrospectively reviewed. Three-phase helical CT scans were obtained at 30 sec(hepatic arterial phase, AP), 70 sec(portal venous phase, PP) and 3 min(equilibrium phase, EP) after the start of intravenous infusion of contrast material. We analyzed the number of abscess layers and their enhancement patterns during each phase, and evaluated the size and shape of abscess, the CT attenuation and presence of septae in the abscess cavity, and the thickness and maturation of the granulation layer and collagenous wall. AP images showed that 13 abscesses(59%) had four layers; on PP images, half the abscesses were seen to have three layers, while EP images showed that two-thirds had two layers. Among the 13 abscesses with four layers seen on AP images, all abscess cavities and granulation layers were hypo- and hyperattenuating, respectively, during all three phases. Most hypoattenuating collagenous walls seen on AP images became iso- or hyperattenuating on EP images, while hyperattenuating hyperperfusion zones seen on AP images became isoattenuating during later phases. The degree of maturation of the collagenous wall correlated with the number of abscess layers. As seen on AP, PP and EP thbscess layers. As seen on AP, PP and EP three-phase helical CT images, hepatic abscess frequently had four, three, or two layers respectively. More mature collagenous walls tended to have more abscess layers

241

Directory of Open Access Journals (Sweden)

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.

P. Rathika

2011-09-01

242

Double storey three phase saturated cores fault current limiter

A novel saturated-cores Fault-Current-Limiter (FCL) configuration is described. This FCL is based on two parallel planes of iron rectangular cores, on which three-phase coils are mounted and connected in series to the grid. Two DC coils are mounted in between the planes on perpendicular core limbs connecting the two AC planes. The DC coils are set to magnetically saturate the AC cores. The transition to three-dimensional, double-storey design enables handling three-phase symmetrical faults while offering better decoupling between the AC and DC circuits. At the same time, it shortens the AC limb lengths and enables deeper magnetic saturation levels in comparison to other saturated cores FCL designs. Hence, this FCL configuration exhibits lower insertion impedance and higher ratio of fault to nominal state impedance in comparison with other designs.

Wolfus, Y.; Nikulshin, Y.; Friedman, A.; Yeshurun, Y.

2014-05-01

243

Description of the three-phase contact line expansion

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 experimen...

Váchová Tereza; Brabcová Zuzana; Basa?ová Pavlína

2014-01-01

244

Peripheral cholangiocarcinoma : three-phase helical CT appearance

International Nuclear Information System (INIS)

To analyze the enhancement patterns and morphology of peripheral cholangiocar-cinomas (CCs), as seen on three-phase helical CT. Three-phase helical CT scans of 25 cases of 24 patients with pathologically-proven CCs were retrospectively reviewed. After intravenous administration of contrast media, scans of the hepatic arterial phase (HAP) were obtained at 30 seconds, of the portal venous phase (PVP) at 70 seconds, and of the delayed phase (DP) at 3 minutes. Linear, dense, marginal enhancement was seen in 17 CCs (68%), mainly on HAP images (64%) while thick, band-like, peripheral enhancement was seen in 18 (72%), on either PVP (52%) or DP (44%). Internal enhancement was observed in 23 CCs (92%) on PVP (68%) and/or DP (88%), and 19 CCs (76%) among them showed incomplete enhancement of stippled and/or septated patterns. Most (76%) were seen throughout all three phases to be hypoattenuating, as compared to the surrounding parenchyma. On HAP, wedge-shaped parenchymal enhancement was demonstrated at the periphery of 19 CCs (76%) suggesting impaired portal flow. Associated morphologic findings were satellate nodules (n=15, 60%), lymphadenopathy (n=14, 56%), focal dilatation of intrahepatic ducts around the tumor (44%), umbilication of the liver surface (50%), and clonorchiasis (44%). On three-phase helical CT, peripheral cholangiocarcinoma showed linear marginal enhancement on HAP, thick peripheral enhancement on PVP and/or DP, stippled and septated enhancing foci on DP, and ed and septated enhancing foci on DP, and peritumoral wedge enhancement on HAP. Associated findings such as satellite nodules, focal dilatation of the intrahepatic ducts, umbilication of the tumor, and clonorchiasis were helpful

245

Differential Protection for Arbitrary Three-Phase Power Transformers

This thesis describes how to provide standardized, current based, differential protection for any three-phase power transformer, including phase-shifting transformers with variable phase angle shift and transformers of all construction types and internal on-load tap-changer configurations. The use of standard transformer differential protection for such applications is considered impossible in the protective relaying standards and practices currently applied. The first part of ...

Gajic?, Zoran

2008-01-01

246

Backstepping controller of five-level three-phase inverter

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 des...

Majdoul R.; Abouloifa A.; Abdelmounim E.; Aboulfatah M.; Touati A.; Moutabir A.

2014-01-01

247

Three Phase High Power Quality Two- Stage Boost Rectifier

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...

Nammalvar, P.; Annapoorani, S.

2012-01-01

248

CONCEPTUAL THREE PHASE KDD MODEL AND FINANCIAL RESEARCH

Directory of Open Access Journals (Sweden)

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.

Dr. Simmi Bagga

2013-04-01

249

Three-Phase Harmonic Analysis Method for Unbalanced Distribution Systems

Directory of Open Access Journals (Sweden)

Full Text Available Due to the unbalanced features of distribution systems, a three-phase harmonic analysis method is essential to accurately analyze the harmonic impact on distribution systems. Moreover, harmonic analysis is the basic tool for harmonic filter design and harmonic resonance mitigation; therefore, the computational performance should also be efficient. An accurate and efficient three-phase harmonic analysis method for unbalanced distribution systems is proposed in this paper. The variations of bus voltages, bus current injections and branch currents affected by harmonic current injections can be analyzed by two relationship matrices developed from the topological characteristics of distribution systems. Some useful formulas are then derived to solve the three-phase harmonic propagation problem. After the harmonic propagation for each harmonic order is calculated, the total harmonic distortion (THD for bus voltages can be calculated accordingly. The proposed method has better computational performance, since the time-consuming full admittance matrix inverse employed by the commonly-used harmonic analysis methods is not necessary in the solution procedure. In addition, the proposed method can provide novel viewpoints in calculating the branch currents and bus voltages under harmonic pollution which are vital for harmonic filter design. Test results demonstrate the effectiveness and efficiency of the proposed method.

Jen-Hao Teng

2014-01-01

250

EMC Increasing of PWM Rectifier in Comparison with Classical Rectifier

Directory of Open Access Journals (Sweden)

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.

R. Dolecek

2008-12-01

251

In this master thesis it has been investigated to utilize the matrix as a shunt active power filter and an adjustable speed drive and then compare the matrix converter with the Back-to-Back voltage source converter in terms of active filtering capability and reactive power compensation.In first steps to utilize the matrix converter as a motor drive and a shunt active power filter the control systems for the Permanent magnet synchronous machine, shunt active power filter and 3-phase LC-filter ...

Ali, Imran

2013-01-01

252

Energy Technology Data Exchange (ETDEWEB)

A three-phase transformerless power electronic conversion system is used as an interface between a photovoltaic (PV) array and the utility line. A high efficiency is obtained because a conventional power transformer is not applied and because of a high array voltage. A maximum power point tracker (MPPT) is used for optimal utilization of the PV-array, which results in a high yield of the system. The power electronic converter is based on the topology of a Pulse Width Modulated Current Source Inverter (PWM-CSI). The inverter is operated at a high switching frequency (20 kHz), so that waveforms with a low distortion are generated, while the power factor is near unity. On the ac side as well as on the dc side the harmonics and the ripple components are considered. Performance measurements on a 1kVA-prototype system show that the efficiency of the system increases from 65% at 20% load to 85% at full load. From 20% to full load, the power factor exceeds 0.95. 11 figs., 4 refs.

Veltman, A.T. [Netherlands Energy Research Foundation, Petten (Netherlands); De Haan, S.W.H. [Technische Univ. Eindhoven (Netherlands)

1991-06-01

253

A Single Phase to Three Phase PFC Half-Bridge Converter Using BLDC Drive with SPWM Technique.

Directory of Open Access Journals (Sweden)

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.

Srinu Duvvada

2014-07-01

254

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese 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.

Milton E. de, Oliveira Filho; Alfeu J., Sguarezi Filho; Ernesto, Ruppert.

2012-06-01

255

An NPC/H-bridge modular photovoltaic grid connected inverter with new-phase shifted PWM technique

Energy Technology Data Exchange (ETDEWEB)

The commonly used topologies for converting direct current power generated by solar panels to high quality alternating current power at the interface to the grid are the high- frequency and line frequency voltage source grid interface system. These topologies utilize transformers which come with negative features such as increase in cost, size and weight of the whole inverter. In addition, the efficiency and reliability of the system is reduced. A novel option for inverters is the multilevel concept as it is based on low frequency switching and provides voltage or current of low sharing between the power semiconductors. The key topologies which have been suggested for multilevel converters are diode clamped or neutral point clamped (NPC); capacitor clamped of flying capacitors (FC); and cascaded H-bridge inverters with separate direct current sources. The cascaded H-bridge converter demonstrates superior qualities among the multilevel converter topologies as a result of its modularity and flexibility. This paper investigated the operating principle of a cascaded NPC/H-bridge inverter for photovoltaic-grid application. The superior characteristics of the model were analyzed using the state space techniques and double Fourier principle. A new and improved phase sifted PWM technique was proposed and its performance was compared. The main system configuration, mathematical modeling, and simulation model were presented. The state space equation showed that the model has 8 different operating modes which can be utilized to realize 5 level voltages per cell. 13 refs., 1 tab., 6 figs.

Wanjekeche, T.; Nicolae, D.V.; Jimoh, A.A. [Tshwane Univ. of Technology, Pretoria (South Africa). Dept. of Electrical Engineering

2010-08-13

256

Recent wind farm grid codes require wind generators to ride through voltage sags, which means that normal power production should be re-initiated once the nominal grid voltage is recovered. However, fixed speed wind turbine generator system using induction generator (IG) has the stability problem similar to the step-out phenomenon of a synchronous generator. On the other hand, doubly fed induction generator (DFIG) can control its real and reactive powers independently while being operated in variable speed mode. This paper proposes a new control strategy using DFIGs for stabilizing a wind farm composed of DFIGs and IGs, without incorporating additional FACTS devices. A new current controlled voltage source converter (CC-VSC) scheme is proposed to control the converters of DFIG and the performance is verified by comparing the results with those of voltage controlled voltage source converter (VC-VSC) scheme. Another salient feature of this study is to reduce the number of proportionate integral (PI) controllers used in the rotor side converter without degrading dynamic and transient performances. Moreover, DC-link protection scheme during grid fault can be omitted in the proposed scheme which reduces overall cost of the system. Extensive simulation analyses by using PSCAD/EMTDC are carried out to clarify the effectiveness of the proposed CC-VSC based control scheme of DFIGs.

Okedu, Kenneth Eloghene; Muyeen, S. M.; Takahashi, Rion; Tamura, Junji

257

Voltage Sag Mitigation by PWM Autotransformer Technique

Directory of Open Access Journals (Sweden)

Full Text Available The objective of this research is to develop a novel voltage control scheme that can compensate for voltagesag and swell conditions in three-phase power systems. Faults occurring in power distribution systems or facilities inplants cause the voltage sag or swell. If a fault occurs, it can damage the power system or user's facility. Sensitivity tovoltage sags and swells varies within different applications. For sensitive loads, even voltage sags of short durationcan cause serious problems in the entire system. Normally, a voltage interruption triggers a protection device, whichcauses shutdown of the entire system.

ASHOK L. VAGHAMSHI

2012-06-01

258

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.)

259

Three Phase Probabilistic Load Flow in Radial Distribution Networks

Energy Technology Data Exchange (ETDEWEB)

Probabilistic load flow is a helpful tool in accounting for inconsistent or unknown loads and generation. This is especially true with the push for renewable generation and demand response. This paper proposes an improved version of the probabilistic load flow solution for balanced distribution systems and takes the next step by applying it to unbalanced three phase systems. It is validated by comparing the solutions to that obtained by Monte Carlo simulation. The proposed method provides an accurate and practical way for finding the solution to the stochastic problems occurring in power distribution system analysis today.

Melhorn, Alexander C [ORNL; Dimitrovski, Aleksandar D [ORNL; Tomsovic, Kevin L [ORNL

2012-01-01

260

DEFF Research Database (Denmark)

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.

Teodorescu, Remus; Blaabjerg, Frede

2004-01-01

261

ZAD strategy with lateral PWM applied to a Boost converter

Directory of Open Access Journals (Sweden)

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.

Andr\\u00E9s Amador

2012-01-01

262

Simulation of Single-Phase Cascade Multilevel PWM Inverters

This paper presents simulation of a single –phase cascade multilevel PWM inverter topology.Solution is based on series connection of 3 level diodeclamped inverters modules and flying capacitor invertermodules, which gives possibility for flexible operation ofinverter at various high voltage.

Felicia ?chiop; Adrian ?chiop

2008-01-01

263

Compensation on Hall effect sensor of PWM switching control

International Nuclear Information System (INIS)

In this paper, it mainly investigates the relationship between switching frequency and measured currents of Hall effect sensor. How to effectively measure the current waveforms to improve the PWM switching control performance is the main subject of concern. A compensation circuit is designed to enlarge the operational range of Hall effect sensor, and the measurement error can be reduced without additional temperature sensor

264

Simulation of Single-Phase Cascade Multilevel PWM Inverters

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents simulation of a single –phase cascade multilevel PWM inverter topology.Solution is based on series connection of 3 level diodeclamped inverters modules and flying capacitor invertermodules, which gives possibility for flexible operation ofinverter at various high voltage.

Felicia ?chiop

2008-05-01

265

Stator insulation systems for medium voltage PWM drives fed motors

International Nuclear Information System (INIS)

This paper presents the partial results of a research project that studied the impact of medium voltage PWM ASD (adjustable speed drives) on motor stator insulation system. The findings from this study/ investigation have aided designers to improve the robustness of the insulation system used for ASD-fed motors, based on accelerated laboratory tests. (author)

266

Color adjustable LED driver design based on PWM

Light-emitting diode (LED) is a liquid cold source light source that rapidly develops in recent years. The merits of high brightness efficiency, long duration, high credibility and no pollution make it satisfy our demands for consumption and natural life, and gradually replace the traditional lamp-house-incandescent light and fluorescent light. However, because of the high cost and unstable drive circuit, the application range is restricted. To popularize the applications of the LED, we focus on improving the LED driver circuit to change this phenomenon. Basing on the traditional LED drive circuit, we adopt pre-setup constant current model and introduce pulse width modulation (PWM) control method to realize adjustable 256 level-grays display. In this paper, basing on human visual characteristics and the traditional PWM control method, we propose a new PWM control timing clock to alter the duty cycle of PWM signal to realize the simple gamma correction. Consequently, the brightness can accord with our visual characteristics.

Du, Yiying; Yu, Caideng; Que, Longcheng; Zhou, Yun; Lv, Jian

2012-10-01

267

Inverter Output Filter Effect on PWM Motor Drives of a Flywheel Energy Storage System

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.

Santiago, Walter

2004-01-01

268

Advanced computational model for three-phase slurry reactors

International Nuclear Information System (INIS)

In the first year of the project, solid-fluid mixture flows in ducts and passages at different angle of orientations were analyzed. The model predictions are compared with the experimental data and good agreement was found. Progress was also made in analyzing the gravity chute flows of solid-liquid mixtures. An Eulerian-Lagrangian formulation for analyzing three-phase slurry flows in a bubble column is being developed. The approach uses an Eulerian analysis of gas liquid flows in the bubble column, and makes use of the Lagrangian particle tracking procedure to analyze the particle motions. Progress was also made in developing a rate dependent thermodynamically consistent model for multiphase slurry flows in a state of turbulent motion. The new model includes the effect of phasic interactions and leads to anisotropic effective phasic stress tensors. Progress was also made in measuring concentration and velocity of particles of different sizes near a wall in a duct flow. The formulation of a thermodynamically consistent model for chemically active multiphase solid-fluid flows in a turbulent state of motion was also initiated. 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 to 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

269

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

270

DEFF Research Database (Denmark)

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.

Wang, Xiongfei; Blaabjerg, Frede

2014-01-01

271

This paper is aimed at the characterization of Electric Power Drive Systems based on the Induction Machine fed by Multi-level Voltage-source inverters, to be used within instantaneous torque and flux control methodologies. The input/output transfer function for a N-level inverter is discussed and the correspondent available output voltage vectors, as well as the input sequences that give them rise, represented in the stationary Park reference plane. Concerning the induction machine characterization, an analytical study on the torque and stator flux instantaneous behavior is made, demonstrating that the first one highly depends on the delivered torque and speed. In consequence, a sampling scale predictive model of the induction machine is deduced in order to make possible the optimal choice of the inverter configuration for a sampling period. Finally, a DEADBEAT based control law is discussed and simulated as an illustration example of both the voltage-inverter and induction machine models presented within this paper.

Martins, C. A.; Meynard, T. A.; Roboam, X.; Carvalho, A. S.

1999-01-01

272

Advanced nonlinear control of three phase series active power filter

Directory of Open Access Journals (Sweden)

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.

Abouelmahjoub Y.

2014-01-01

273

Transient three-phase three-component flow. Pt. 3

International Nuclear Information System (INIS)

A mathematical model of a transient three-dimensional three-phase three-component flow described by three-velocity fields in porous body is presented. A combination of separated mass and energy equations together with mixture momentum equations for the flow is used. The mixture equations are used in diffusion form with the assumption that the diffusion velocity can be calculated from empirical correlations. An analytical coupling between the governing equations is developed for calculation of the pressure field. The system is discretized semiimplicitly in 3D-cylindrical space and different solution methods for the algebraic problem are presented. Finally, numerical examples and comparisons with experimental data demonstrate that the method presented is a powerful tool for numerical multiphase flow simulation. (orig.)

274

Three-phase unbalanced load flow tool for distribution networks

Energy Technology Data Exchange (ETDEWEB)

This work develops a three-phase unbalanced load flow tool tailored for radial distribution networks based on Matlab {sup registered}. 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 system 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 solutions tool in the sense of resulting bus voltage magnitudes is compared and validated with IEEE 13-bus test feeder. (orig.)

Demirok, Erhan; Sera, Dezso; Teodorescu, Remus [Aalborg Univ. (Denmark). Dept. of Energy Technology; Kjaer, Soeren B. [Danfoss Solar Inverters A/S, Sonderborg (Denmark)

2012-07-01

275

Simplified three-phase transformer model for electromagnetic transient studies

Energy Technology Data Exchange (ETDEWEB)

This paper presents a simplified high-frequency model for three-phase, two- and three-winding transformers. The model is based on the classical 60-Hz equivalent circuit, extended to high frequencies by the addition of the winding capacitances and the synthesis of the frequency-dependent short-circuit branch by an RLC equivalent network. By retaining the T-form of the classical model, it is possible to separate the frequency-dependent series branch from the constant-valued shunt capacitances. Since the short-circuit branch can be synthesized by a minimum-phase-shift rational approximation, the mathematical complications of fitting mutual impedance or admittance functions are avoided and the model is guaranteed to be numerically absolutely stable. Experimental tests were performed on actual power transformers to determine the parameters of the model. EMTP simulation results are also presented.

Chimklai, S.; Marti, J.R. [Univ. of British Columbia, Vancouver, British Columbia (Canada)

1995-07-01

276

One dimensional speckle fields generated by three phase level diffusers

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.

Cabezas, L.; Amaya, D.; Bolognini, N.; Lencina, A.

2015-02-01

277

Analysis of Dither in PWM Control on Electro-hydraulic Proportional Valve

Directory of Open Access Journals (Sweden)

Full Text Available Plus with modulation (PWM is widely used in proporational control systems for it is efficient, flexible and anti-interference. Due to the friction and hysteresis of electromagnet, hysteresis exists when hydraulic valve in steady-state, and hysteresis influences the dynamic characteristics of the valve seriously,the hysteresis can be improved by superimposing dithers with certain frequency and amplitude to the valve coil. Aiming at the character of anti-unloading power driver circuit ,this paper analyzed the parasitic dither which exists in ±24V PWM control?besides?the experiment shows that in a high frequency PWM, dither with independent frequency and amplitude can be generated by changing the frequency of the PWM, in this way, the dithers and average current of coil can be adjusted separately by changing PWM frequency and PWM duty cycle.

Guoping LIU

2013-11-01

278

Area Equalization PWM Techniques for Single-Phase Full Bridge Inverter with Fluctuating DC Input

An extension of equal sampling technique (EST) based pulse width modulation (PWM) is presented for the single-phase inverter to reduce lower order harmonics caused by the fluctuating dc input. In the EST, which has been proposed earlier for constant dc, the width of PWM pulses is determined by making the area of the PWM signal equal to the area under the sampled reference waveform. The concept of equal area criterion equally applicable for fluctuating dc input with required modifications of t...

Pavankumar, G.; Dananjayan, P.; Jeevananthan, S.

2007-01-01

279

Controlling DC Motor using Microcontroller (PIC16F72) with PWM

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...

Shruti Shrivastava, Jageshwar Rawat

2012-01-01

280

Space Vector PWM Control of Dual Inverter Fed Open-End Winding Induction Motor Drive

A space vector PWM technique is developed based on the combination of space vectors from dual inverters feeding the induction motor from both ends (open-end winding without neutral point). A total of 64 voltage space vector combinations are available for PWM voltage control of the inverter fed machine with open-end winding. A space phasor based PWM scheme is proposed with minimum number of switching in a cycle per inverter coupled with equal number of switching for each inverter.

Shivakumar, Eg; Gopakumar, K.; Sinha, Sk; Pittet, Andrei; Ranganathan, Vt

2001-01-01

281

Description of the three-phase contact line expansion

Directory of Open Access Journals (Sweden)

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.

Váchová Tereza

2014-03-01

282

Description of the three-phase contact line expansion

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.

Váchová, Tereza; Brabcová, Zuzana; Basa?ová, Pavlína

2014-03-01

283

Bone graft viability evaluated by three phase bone scan

International Nuclear Information System (INIS)

Bone defects resulting war injury can be replaced by microvascular bone grafts from fibula. Aim: The aim of this study was to assess the value of three phase (3P) bone scintigraphy in the early detection of the bone graft complications. Method: 3P bone scans were performed in four patients (two after mandible reconstruction with micro vascular fibular bone grafts, one after fibular transplantation for ulnar and one with humeral reconstruction). First dynamic phase scan was performed immediately after iv injection of 740 MBq Tc-99m DPD, acquiring 15 two seconds duration frames. Second, early static scan was performed during next 300 seconds, and third, delayed scan three hours later. All scans were obtained under the bone graft region. The scans were evaluated using ROI under graft region and the corresponding contra lateral area. Blood flow in graft region was determined using first phase scan, and tracer uptake in the same region was determined using second and third phase scans. Results: in all patients blood flow in graft region was particularly normal. Tracer uptake in one of two patients with mandible reconstruction was diffusely increased in graft, strongly suggesting infection; In the other patient delayed scan showed no tracer uptake in graft center .Both patients with ulnar and humeral reconstruction showed only slightly decreased tracer uptake in bone grafts. 3 phase bone scintigraphy may play a role in the evaluation of bone graft viability by pre evaluation of bone graft viability by predicting the infection and necrosis. (authors)

284

Three-phase inverter for small high speed motors

A high-frequency three-phase inverter is being developed to drive a miniature centrifugal compressor which is a key component in a long-life space-borne cryocooler. The inverter is a unique transformer-coupled design, tailored to the low-voltage high-current characteristic of the compressor's induction motor. The design and performance demonstration of a breadboard model of the inverter are described. The cryocooler uses a reverse-Brayton cycle with turbomachines to provide 5 watt of cooling at 70 K. The design target for input power to the compressor motor is 175 watts. Line-to-neutral phase voltage waveforms to be supplied by the inverter have an amplitude of 15 volt-rms at a frequency of 8 kHz. DC power at 28 volt is supplied to the inverter. The breadboard inverter was tested with a preliminary development model of the compressor. It drove the compressor over a range of operating conditions encompassing frequencies of 5 to 9 kHz at powers of 56 to 437 watt. Inverter efficiencies, calculated from experimentally verified loss models, ranged from 89 to 95 percent over the tests. The design target on efficiency is 90 percent. The inverter was demonstrated to supply starting current adequate to overcome the starting friction of the compressor's self-acting gas bearings by a safe margin.

Mccormick, John A.; Valenzuela, Javier A.

1991-01-01

285

ISOBUTANOL FROM SYNGAS IN A THREE PHASE SYSTEM

Energy Technology Data Exchange (ETDEWEB)

With growing interest in oxygenates as octane booster for automotive fuels, various synthesis routes for these chemicals are being investigated. Among others, alternative routes to isobutene, the C4-components in MTBE-synthesis are under investigation. A promising path to isobutene is the heterogeneously catalyzed CO-hydrogenation to isobutanol with following dehydration (Fig. 1). As shown by thermodynamical studies, the heterogeneously catalyzed CO-hydrogenation to isobutanol is not expected to experience any thermodynamic constraints. However, heterogeneous hydrogenation of CO is a very exothermic process, a problem which can only be partly solved when being conducted in a plug flow reactor. When carried out in reaction vessels with moving catalyst bed (e.g. three phase stirred tank), heat transfer problems can be resolved, along with additional benefits connected with this reactor type. Several heterogeneous catalytic systems have been under investigation for their capability of isobutanol synthesis from syngas. Most promising catalysts for an active and selective isobutanol synthesis from CO are modified high temperature methanol catalysts.

Peter Tijrn

2002-12-29

286

Clinical significant of three phase radionuclide bone scan

International Nuclear Information System (INIS)

Three phase radionuclide bone scan, consisting of a radionuclide angiogram, an immediate postinjection blood pool image, and 4hr delayed images, was randomly performed in 182 patients, who had been suffered from either local pain or tenderness. Authors analysed 3 phase bone scan in 74 patients with correct diagnosis proven surgically or clinically, from July 1987 to August, 1988. The results were as follows: 1. Overall sensitivity of 3 phase bone scan was 85.4%: sensitivity in patients with an osseous lesion was 90.4% as opposed to 72.7% in patients with a nonosseous lesion. 2. There was no difference in the detection rate of the osseous lesions between the 3 phase bone scan and the delayed image bone scan. However, because the detection rate was higher on the 3 phase bone scan than it was on only the delayed image bone scan (55%) in instance of the nonosseous lesion, we would suggest that 3 phase bone scan might be obtained in cases suspected of the nonosseous lesions. 3. When the presumptive diagnosis was a bone tumor, sensitivity and specificity for malignancy were 67%, 100% respectively. 4. In differentiating osteomyelitis from cellulitis, sensitivity was 94%, specificity was 100%. 5. 3 phase bone scan was able to provide the precise information about either vasculaturity or localization of lesion in some cases of soft tissue mass and avascular necrosis of hips

287

Deterministic approach to microscopic three-phase traffic theory

A deterministic approach to three-phase traffic theory is presented. Two different deterministic microscopic traffic flow models are introduced. In an acceleration time delay model (ATD-model), different time delays in driver acceleration associated with driver behavior in various local driving situations are explicitly incorporated into the model. Vehicle acceleration depends on local traffic situation, i.e., whether a driver is within the free flow, or synchronized flow, or else wide moving jam traffic phase. In a speed adaptation model (SA-model), driver time delays are simulated as a model effect: Rather than driver acceleration, vehicle speed adaptation occurs with different time delays depending on one of the three traffic phases in which the vehicle is in. It is found that the ATD- and SA-models show spatiotemporal congested traffic patterns that are adequate with empirical results. It is shown that in accordance with empirical results in the ATD- and SA-models the onset of congestion in free flow at a...

Kerner, B S; Kerner, Boris S.; Klenov, Sergey L.

2005-01-01

288

A three-phase approach for operating theatre schedules.

In this paper we develop a three-phase, hierarchical approach for the weekly scheduling of operating rooms. This approach has been implemented in one of the surgical departments of a public hospital located in Genova (Genoa), Italy. Our aim is to suggest an integrated way of facing surgical activity planning in order to improve overall operating theatre efficiency in terms of overtime and throughput as well as waiting list reduction, while improving department organization. In the first phase we solve a bin packing-like problem in order to select the number of sessions to be weekly scheduled for each ward; the proposed and original selection criterion is based upon an updated priority score taking into proper account both the waiting list of each ward and the reduction of residual ward demand. Then we use a blocked booking method for determining optimal time tables, denoted Master Surgical Schedule (MSS), by defining the assignment between wards and surgery rooms. Lastly, once the MSS has been determined we use the simulation software environment Witness 2004 in order to analyze different sequencings of surgical activities that arise when priority is given on the basis of a) the longest waiting time (LWT), b) the longest processing time (LPT) and c) the shortest processing time (SPT). The resulting simulation models also allow us to outline possible organizational improvements in surgical activity. The results of an extensive computational experimentation pertaining to the studied surgical department are here given and analyzed. PMID:17608057

Testi, Angela; Tanfani, Elena; Torre, Giancarlo

2007-06-01

289

A microcontroller based voltage space vector modulator suitable for induction motor drives

Pulse width modulation techniques (PWM), introduced two decades ago, are the most used methods to control the voltage and frequency supplied to electrical AC machines. This paper describes a pulse width modulator based on the voltage space vectors technique that accepts voltage demands in dq coordinates and generates three phase PWM waveforms to drive a variable frequency voltage source inverter. A scheme based on a high performance 16 bit standard microcontroller with minimum of additional h...

Minas, Grac?a; Martins, Ju?lio S.; Couto, Carlos

1999-01-01

290

Effects of 60Co ?-rays on PWM and LPS induced lymphocytes

International Nuclear Information System (INIS)

The relationship between lymphocytes induced by PWM and LPS was investigated by means of 3H-TdR and 14C-UR incorporation. The study showed that in votro, PWM-induced cells were able to promote the stimulating effect of LPS to B lymphocyte. The stimulating effect of PWM-induced cells was obviously weakened after PWM cells being irradiated with ?-rays. When PWM-induced cells and LPS-induced cells were incubated together, with one kind of cells exposed to 60Co ?-rays, incorporation value of 3H-TdR became much smaller and the synergetic function disappeared, especially, when PWM-induced cells were irradiated. For patients suffering from carcinoma of nasopharynx, when treated with 60Co ?-rays, the incorporation value in LPS-induced cells approached normal level, while the incorporation value in PWM-induced cells reduced significantly and the stimulating effect of PWM-induced cells on LPS-induced cells became much weaker. The fact described above demonstrated that PWM-induced cells have the function of T-helper cells and play a more important role in the synergy than LPS induced cells

291

Analysis and Design of a Higher Current ZVS-PWM Converter for Industrial Applications

Directory of Open Access Journals (Sweden)

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.

Navid Golbon

2013-03-01

292

Soft Switched Multi-Output PWM DC-DC Converter

Directory of Open Access Journals (Sweden)

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.

Rashmi Sharma

2013-07-01

293

Energy Technology Data Exchange (ETDEWEB)

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)

Suul, Jon Are

2012-03-15

294

Single Phase Bidirectional PWM Converter for Microgrid System

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 ...

Kalavalli, C.; Parkavikathirvelu, K.; Balasubramanian, R.

2013-01-01

295

CARRIER OVERLAPPING PWM METHODS FOR ASYMMETRICAL MULTILEVEL INVERTER

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...

Seyezhai, Dr R.

2011-01-01

296

Voltage Balancing in Diode Clamped Multilevel Inverter Using Sinusoidal PWM

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...

Shalini, S.

2013-01-01

297

Power electronic converters PWM strategies and current control techniques

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.

Monmasson, Eric

2013-01-01

298

A quantitative dimming method for LED based on PWM

Traditional light sources were required to provide stable and uniform illumination for a living or working environment considering performance of visual function of human being. The requirement was always reasonable until non-visual functions of the ganglion cells in the retina photosensitive layer were found. New generation of lighting technology, however, is emerging based on novel lighting materials such as LED and photobiological effects on human physiology and behavior. To realize dynamic lighting of LED whose intensity and color were adjustable to the need of photobiological effects, a quantitative dimming method based on Pulse Width Modulation (PWM) and light-mixing technology was presented. Beginning with two channels' PWM, this paper demonstrated the determinacy and limitation of PWM dimming for realizing Expected Photometric and Colorimetric Quantities (EPCQ), in accordance with the analysis on geometrical, photometric, colorimetric and electrodynamic constraints. A quantitative model which mapped the EPCQ into duty cycles was finally established. The deduced model suggested that the determinacy was a unique individuality only for two channels' and three channels' PWM, but the limitation was an inevitable commonness for multiple channels'. To examine the model, a light-mixing experiment with two kinds of white LED simulated variations of illuminance and Correlation Color Temperature (CCT) from dawn to midday. Mean deviations between theoretical values and measured values were obtained, which were 15lx and 23K respectively. Result shows that this method can effectively realize the light spectrum which has a specific requirement of EPCQ, and provides a theoretical basis and a practical way for dynamic lighting of LED.

Wang, Jiyong; Mou, Tongsheng; Wang, Jianping; Tian, Xiaoqing

2012-10-01

299

Design and Implementation of carrier based Sinusoidal PWM Inverter

Directory of Open Access Journals (Sweden)

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].

PANKAJ H ZOPE

2013-04-01

300

Directory of Open Access Journals (Sweden)

Full Text Available This study presents a shunt-Connected Voltage Source Convertor (VSC to mitigate balanced and unbalanced voltage sag and regulate the grid voltage at a fixed level by inserting required reactive power at the Point of Common Coupling (PCC. Moreover, an inner Vector Current-Controller (VCC and outer voltage controller (VVC are applied together to calculates the current references for the VCC. Furthermore, an inductor/ capacitor/inductor (LCL filter is replaced with the simple L-filter in between the VSC and the network and it is constructed to reduce the voltage sag. Likewise, to make up for the unbalanced dips, the positive and negative sequence components related to the grid voltage should be managed distinctly. The positive and negative sequence components related to the grid voltage should be managed distinctly. This is achieved through the application of two independent controllers for the two sequences with an identical cascade structure which has been explicated above. Simulation results designate proper functioning of the control system which has been proposed.

Abdollah Shokri

2013-08-01

301

ADVANCED COMPUTATIONAL MODEL FOR THREE-PHASE SLURRY REACTORS

Energy Technology Data Exchange (ETDEWEB)

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.

Goodarz Ahmadi

2004-10-01

302

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

303

Hysteresis in Analytical Solutions for Three-phase Flow

Hysteresis in relative permeability is a widely-recognized phenomenon that impacts oil recovery in water and gas (WAG) injection. Several authors (1-3) have constructed analytical solutions for two-phase oil/water or gas/water flow in enhanced oil recovery however, analytical solutions have not previously been constructed for the three-phase flow problem for immiscible water, oil and gas including hysteresis. In this work analytical solutions are constructed for water and gas floods in a previously water-flooded oil reservoir with and without hysteresis. A simplified model is used in the analysis that qualitatively captures the behavior of oil-phase hysteresis for repeated water imbibition and drainage cycles. Many of the displacements considered have a reversal of flow direction within the displacement, requiring a matching condition to be enforced between the imbibition and drainage relative permeability curves at the point of flow reversal. A suitable matching criterion for the hysteretic curves is presented. A single water/gas injection mixture is considered, with varying initial oil and water volumes present in the reservoir. When hysteresis occurs in a displacement the entire saturation path depends on the initial volumes of oil and water present at the onset of WAG flooding. When hysteresis is ignored most of the displacement is identical for a large range of initial oil and water mixtures, with only the velocity of the leading shock changing. For the displacements which only encounter drainage of the water phase, solutions with and without hysteresis are identical. 1) K. M. Furati, ``Effects of Relative Permeability History Dependence on Two-Phase Flow in Porous Media,'' Transport in Porous Media 28: 181-203, 1997. 2) B. Plohr, D. Marchesin, P. Bedrikovetsky and P. Krause, ``Modeling hysteresis in porous media flow via relaxation,'' Computational Geosciences 5: 225-256, 2001. 3) F. M. Van Kats and C. J. Van Duijn, ``A Mathematical Model for Hysteretic Two-Phase Flow in Porous Media,'' Transport in Porous Media 43: 239-263, 2001.

Lambers, J. V.; LaForce, T.

2011-12-01

304

...Low- and medium-voltage circuits serving three-phase alternating current...Low- and medium-voltage circuits serving three-phase alternating current...Low- and medium-voltage power circuits serving three-phase...

2010-07-01

305

Research on a New Control Strategy of Three Phase Inverter for Unbalanced Loads

Directory of Open Access Journals (Sweden)

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.

Chunxi LIU

2010-01-01

306

High flexibility and low cost digital implementation for modern PWM strategies

DEFF Research Database (Denmark)

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.

Mathe, Laszlo; Sera, Dezso

2011-01-01

307

Generalisation of Helmholtz-Thevenin theorem to three-phase electrical circuits

The scope of this paper is to determine the generalized form for equivalent tension generator theorem (Helmholtz-Thevenin theorem) for three-phase electrical circuit. Any complicated electrical power systems we can reduce depending on any three-phase electrical consumer to a three-phase electrical generator that has certain internal impedance. Starting with this assumption, we have demonstrated the way to obtain the electromotive voltages for an equivalent generator and its internal impedances.

Mihai, Gheorghe

2009-01-01

308

Research on a New Control Strategy of Three Phase Inverter for Unbalanced Loads

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...

Liu, Chunxi; Weiming Ma; Hu, Wenhua

2010-01-01

309

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...

Vandoorn, Tine L.; Kooning, Jeroen D. M.; Jan Van de Vyver; Lieven Vandevelde

2013-01-01

310

This paper deals with a fault detection technique for insulated-gate bipolar transistors (IGBTs) open-circuit faults in voltage source inverter (VSI)-fed induction motor drives. The novelty of this idea consists in analyzing the pulse-width modulation (PWM) switching signals and the line-to-line voltage levels during the switching times, under both healthy and faulty operating conditions. The proposed method requires line-to-line voltage measurement, which provides information about switching states and is not affected by the load. The fault diagnosis scheme is achieved using simple hardware and can be included in the existing inverter system without any difficulty. In addition, it allows not only accurate single and multiple faults diagnosis but also minimization of the fault detection time to a maximum of one switching period (T(c)). Simulated and experimental results on a 3-kW squirrel-cage induction motor drive are displayed to validate the feasibility and the effectiveness of the proposed strategy. PMID:22153956

Trabelsi, Mohamed; Boussak, Mohamed; Gossa, Moncef

2012-03-01

311

Spread Spectrum Modulation by Using Asymmetric-Carrier Random PWM

DEFF Research Database (Denmark)

This paper presents a new fixed carrier frequency random PWM method, where a new type of carrier wave is proposed for modulation. Based on simulations and experimental measurements, it is shown that the spread effect of the discrete components from the motor current spectra and acoustic spectra is very effective and is independent from the modulation index. The flat motor current spectrum generates an acoustical noise close to the white noise, which improves the acoustical performance of the drive. The new carrier wave is easy to implement digitally, without employing any external circuits. The modulation method can be used in both open and closed loop motor control applications.

Mathe, Laszlo; Lungeanu, Florin

2012-01-01

312

Simulink Implementation of PWM Strategies for Diode Clamped MLI

Directory of Open Access Journals (Sweden)

Full Text Available Multilevel inverters has got more concern over conventional two level inverters because of their features like yielding output with low harmonics, output tending to sinusoidal, the voltage stress across each switching device is low. The diode clamped inverter is widely multilevel inverter configuration due to ease of operation when compared to other topologies. The variation in output voltage magnitude and frequency is achieved using various modulation strategies. In this paper various PWM strategies are implemented for three level and five level diode clamped MLI and results are compared.

V.Harish

2014-04-01

313

Full Wave Mode ZVT-PWM DC-DC Converters

Energy Technology Data Exchange (ETDEWEB)

This paper proposes a full wave model ZVT-PWM boost converter. The converter with the auxiliary switch in a full wave mode makes possible soft switching operation of all switches including the auxiliary switch whereas the auxiliary switch is turned of with hard switching in the conventional converter. Therefore, the proposed converter reduces the turn-off switching loss and switching noise of the auxiliary switch without additional passive and/or active elements and high power density system can be realized. (author). 5 refs., 10 figs., 2 tabs.

Kim, Tae Woo; Ahn, Hee Wook; Kim, Hack Sung [Kumoh National University of Technology, Kumi (Korea)

2001-06-01

314

The performance of different current controller structures for Voltage Source Converters (VSC) under weak grid conditions caused by large grid impedance is investigated. The VSC is synchronized to the grid by a Phase Locked Loop (PLL). Current control techniques and PLL techniques for handling both symmetrical and asymmetrical conditions are presented and discussed. The investigated current control structures are; the conventional Proportional Integral (PI)-controller in the synchronous rotat...

Midtsund, Tarjei

2010-01-01

315

The performance of different current controller structures for Voltage Source Converters (VSC) under weak grid conditions caused by large grid impedance is investigated. The VSC is synchronized to the grid by a Phase Locked Loop (PLL). Current control techniques and PLL techniques for handling both symmetrical and asymmetrical conditions are presented and discussed. The investigated current control structures are; the conventional Proportional Integral (PI)-controller in the synchronous rotat...

Midtsund, Tarjei

2010-01-01

316

HF common mode EMC modeling of AC three-phase motors

The research presented in this report addresses the problem of electromagnetic compatibility (EMC) in AC motors, which are supplied by PWM inverters, through the predictive modeling of the common mode impedance as well as aspect related to bearing voltage. We begin with identification of the parameters that govern the propagation path of common mode currents in the metallic parts of induction machines using finite element (FE) method. From analysis of the results, a circuit model was proposed...

Boucenna, Nidhal

2014-01-01

317

30 CFR 77.901 - Protection of low- and medium-voltage three-phase circuits.

...Protection of low- and medium-voltage three-phase circuits. 77.901 Section...Protection of low- and medium-voltage three-phase circuits. (a) Low- and...voltage equal to the phase-to-phase voltage of the system. (c)...

2010-07-01

318

Directory of Open Access Journals (Sweden)

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.

Md. Aziz Ul Huq

2013-05-01

319

Distortion-Free 1-Bit PWM Coding for Digital Audio Signals

Directory of Open Access Journals (Sweden)

Full Text Available Although uniformly sampled pulse width modulation (UPWM represents a very efficient digital audio coding scheme for digital-to-analog conversion and full-digital amplification, it suffers from strong harmonic distortions, as opposed to benign non-harmonic artifacts present in analog PWM (naturally sampled PWM, NPWM. Complete elimination of these distortions usually requires excessive oversampling of the source PCM audio signal, which results to impractical realizations of digital PWM systems. In this paper, a description of digital PWM distortion generation mechanism is given and a novel principle for their minimization is proposed, based on a process having some similarity to the dithering principle employed in multibit signal quantization. This conditioning signal is termed “jither” and it can be applied either in the PCM amplitude or the PWM time domain. It is shown that the proposed method achieves significant decrement of the harmonic distortions, rendering digital PWM performance equivalent to that of source PCM audio, for mild oversampling (e.g., ×4 resulting to typical PWM clock rates of 90 MHz.

John Mourjopoulos

2007-01-01

320

Distortion-Free 1-Bit PWM Coding for Digital Audio Signals

Directory of Open Access Journals (Sweden)

Full Text Available Although uniformly sampled pulse width modulation (UPWM represents a very efficient digital audio coding scheme for digital-to-analog conversion and full-digital amplification, it suffers from strong harmonic distortions, as opposed to benign non-harmonic artifacts present in analog PWM (naturally sampled PWM, NPWM. Complete elimination of these distortions usually requires excessive oversampling of the source PCM audio signal, which results to impractical realizations of digital PWM systems. In this paper, a description of digital PWM distortion generation mechanism is given and a novel principle for their minimization is proposed, based on a process having some similarity to the dithering principle employed in multibit signal quantization. This conditioning signal is termed "jither" and it can be applied either in the PCM amplitude or the PWM time domain. It is shown that the proposed method achieves significant decrement of the harmonic distortions, rendering digital PWM performance equivalent to that of source PCM audio, for mild oversampling (e.g., resulting to typical PWM clock rates of 90 MHz.

Mourjopoulos John

2007-01-01

321

PWM Based Automatic Closed Loop Speed Control of DC Motor

Directory of Open Access Journals (Sweden)

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.

Atul Kumar Dewangan, Nibbedita Chakraborty, Sashi Shukla, Vinod Yadu

2012-04-01

322

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

323

Instantaneous Power Compensation in Three-Phase Systems by Using p-q-r Theory

DEFF Research Database (Denmark)

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.

Kim, Hyosung; Blaabjerg, Frede

2002-01-01

324

Adaptive nonlinear control of single-phase to three-phase UPS system

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 control...

Kissaoui M.; Abouloifa A.; Giri F.; Chaoui F.Z.; Abouelmahjoub Y.

2014-01-01

325

A PWM transistor inverter for an ac electric vehicle drive

A prototype system consisting of closely integrated motor, inverter, and transaxle has been built in order to demonstrate the feasibility of a three-phase ac transistorized inverter for electric vehicle applications. The microprocessor-controlled inverter employs monolithic power transistors to drive an oil-cooled, three-phase induction traction motor at a peak output power of 30 kW from a 144 V battery pack. Transistor safe switching requirements are discussed, and a circuit is presented for recovering trapped snubber inductor energy at transistor turn-off.

Slicker, J. M.

1981-01-01

326

A PWM transistor inverter for an ac electric vehicle drive

A prototype system consisting of closely integrated motor, inverter, and transaxle has been built in order to demonstrate the feasibility of a three-phase ac transistorized inverter for electric vehicle applications. The microprocessor-controlled inverter employs monolithic power transistors to drive an oil-cooled, three-phase induction traction motor at a peak output power of 30 kW from a 144 V battery pack. Transistor safe switching requirements are discussed, and a circuit is presented for recovering trapped snubber inductor energy at transistor turn-off.

Slicker, J. M.

1981-10-01

327

Multicarrier trapezoidal PWM strategies based on control freedom degree for MSMI

This work proposes an additional clew for the carrier based PWM methods on control of multilevel inverters which is based on the combination of the Control Freedom Degree (CFD) and novel carrier/reference signals for multilevel cascaded inverter. The significance of the proposed CFD clew on multilevel PWM techniques are verified and well demonstrated by simulation for chosen five level inverter. This paper presents a novel approach for controlling the harmonics of output voltage of chosen Cas...

Bensraj, R.; Natarajan, S. P.; Padmathilagam, V.

2010-01-01

328

Telah dilakukan perancangan sebuah pemanas air (heater) yang suhunya dikendalikan dengan menggunakan PWM. Sebagai pusat pengendalian dari seluruh alat yang dirancang digunakan mikrokontroler ATmega8535. Selain itu sistem yang dirancang dilengkapi dengan sebuah sensor suhu jenis LM35 yang digunakan untuk mendeteksi setiap perubahan temperatur yang terjadi pada heater yang hasilnya akan ditampilkan ke LCD. PWM merupakan sebuah metode untuk membangkitkan sinyal keluaran yang pe...

Gultom, Leothamrin

2011-01-01

329

Led spectral and power characteristics under hybrid PWM/AM dimming strategy

In order to dim LEDs the pulse width modulation (PWM) or amplitude modulation (AM) dimming scheme is typically used. Previous studies show that these dimming schemes can have opposite effects on diodes peak wavelength shift. An experimental study was conducted to test the behavior of InGaN diodes and phosphor-converted white diodes under hybrid PWM/AM modulation. Feed forward control schemes that provide stable peak wavelength position during dimming and the ability to compensate the thermall...

Beczkowski, Szymon; Munk-nielsen, Stig

2010-01-01

330

Parametric algorithms for frequency estimation in PWM converter systems

Energy Technology Data Exchange (ETDEWEB)

Proper estimation of voltage parameters has a significant meaning for power converters control systems. One of the measured parameter, directly associated with control process, is frequency of the basic voltage component at the converter output. Unfortunately, power converters generate a wide spectrum of harmonics as well as interharmonics, that makes difficulties in estimation this frequency. Measurement carried out in industrial applications exhibits complex nature of investigated signals often corrupted by resonances or overvoltages phenomena. It entails searching a new digital algorithms for frequency measurement. This work presents algorithm using modification of high-resolution Prony method connected with digital filtering. The investigations was based on simulations and real measured signals recorded in two different commercial PWM converters. Obtained results indicate accuracy of the method as well as its fast response. (author)

Lobos, T.; Hejke, I.; Rezmer, J.; Sikorski, T.; Kostyla, P. [Dept. of Electrical Engineering, Wroclaw University of Technology, Wyb. Wyspianskiego 27, 50-370 Wroclaw (Poland)

2009-11-15

331

Single Phase Bidirectional PWM Converter for Microgrid System

Directory of Open Access Journals (Sweden)

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.

C.Kalavalli

2013-06-01

332

CARRIER OVERLAPPING PWM METHODS FOR ASYMMETRICAL MULTILEVEL INVERTER

Directory of Open Access Journals (Sweden)

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.

DR.R.SEYEZHAI

2011-08-01

333

Voltage Balancing in Diode Clamped Multilevel Inverter Using Sinusoidal PWM

Directory of Open Access Journals (Sweden)

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.

S.Shalini

2013-12-01

334

Soft switching PWM isolated boost converter for fuel cell application

Energy Technology Data Exchange (ETDEWEB)

This presentation introduced a newly developed soft switching, isolated boost type converter for fuel cell applications. With a simple PWM control circuit, the converter achieves zero voltage switching the main switch. Since the auxiliary circuit is soft switched, the converter can operate at high powers which make it suitable for fuel cell applications. In particular, the converter is suitable for the interface of fuel cell and inverters because of its high voltage gain and isolation between input and output sources. In addition, the input current of the converter (current drained from the fuel cell) is almost constant since it is a boost type converter. The converter was analyzed and the simulation results validate the theoretical analysis.

Rezaei, M.; Adib, E. [Isfahan Univ. of Technology, Isfahan (Iran, Islamic Republic of)

2009-07-01

335

Novel, Four-Switch, Z-Source Three-Phase Inverter

DEFF Research Database (Denmark)

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.

Antal, Robert; Muntean, Nicolae

2010-01-01

336

Investigation of a three-phase-single-phase induction electric drive under stochastic loads

Directory of Open Access Journals (Sweden)

Full Text Available A control system for a three-phase-single- phase induction electric drive with a controlled phase-shifting module is developed and studied to result in a symmetric regime under stochastic load variations.

Yu.V. Shurub

2014-04-01

337

A reverse mode of three-phase asynchronous motors with hexaphase windings

Directory of Open Access Journals (Sweden)

Full Text Available A reverse operation feasibility in three-phase asynchronous motors with the stator hexaphase windings is proved. In the reverse mode, the hexaphase windings are shown to keep all their declared advantages.

V.D. Lushchyk

2014-04-01

338

Fast Unbalanced Three-phase Adjustment Base on Single-phase Load Switching

Directory of Open Access Journals (Sweden)

Full Text Available To balance three-phase loads in distribution network with abundant of single-phase loads, a new wiring method and three-phase loads adjustment policy was proposed in this paper. In the wiring method, a single-phase load was connected with phase A, B and C of trunk line by a controller. When the load of trunk line was unbalanced, the controller will switch the connected single-phase loads from one phase to another to balance it. The minimum count of loads adjustment algorithm and the most balance adjustment algorithm were proposed, which can adjust the three-phase load of trunk line to roughly balance automatically. This method can solve the serious three-phase unbalance problems of the trunk lines with aboundant of single-phase loads. It may instead of capacitive compensation in low voltage distribution network to improve power quality and reduce network losses.

Yanwei Zheng

2013-08-01

339

ELECTROMAGNETIC CALCULATION OF THREE-PHASE ASYNCHRONOUS MOTORS WITH A SIX-PHASE WINDING

Directory of Open Access Journals (Sweden)

Full Text Available Features of electromagnetic computation of three-phase asynchronous motors with a six-phase winding in the stator are described. Experimental data on a conveyor motor with two six-phase windings are given.

S.Yu. Polez?n

2013-02-01

340

ELECTROMAGNETIC CALCULATION OF THREE-PHASE ASYNCHRONOUS MOTORS WITH A SIX-PHASE WINDING

Features of electromagnetic computation of three-phase asynchronous motors with a six-phase winding in the stator are described. Experimental data on a conveyor motor with two six-phase windings are given.

Yu Polez?n, S.; Kiryanov, V. V.; Lushchyk, V. D.

2013-01-01

341

Efficiency analysis on a two-level three-phase quasi-soft-switching inverter

DEFF Research Database (Denmark)

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.

Geng, Pan; Wu, Weimin

2013-01-01

342

The effects of viscous forces on three-phase relative permeability

Energy Technology Data Exchange (ETDEWEB)

The overall objective of Three-Phase Relative Permeability Project (BE9) is to develop guidelines for improving the accuracy of three-phase relative permeability determinations. This report summarizes previous studies and explains the progress made at NIPER on studying the effect of variations in viscous forces on three-phase relative permeabilities by changing the viscosity of both wetting and nonwetting phases. Significant changes were observed due to viscosity variations. An increase in oil viscosity reduced the relative permeability to gas; an increase in brine/(wetting-phase) viscosity reduced the relative permeability to brine. A slight increase in gas relative permeability was also observed. These observations suggest that the viscosities of both oil and water influence three-phase permeability data. During this study, data scatter was sometimes encountered which was comparable to that of published results. The causes of this scatter are outlined in this report and remedial attempts are discussed. 20 refs., 16 figs., 5 tabs.

Maloney, D.R.; Mahmood, S.M.; Honarpour, M.M.

1989-04-01

343

Fuzzy Logic Controller Based Three-phase Shunt Active Filter for Line Harmonics Reduction

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...

Sharmeela, C.; Mohan, M. R.; Uma, G.; Baskaran, J.

2007-01-01

344

The excellent insulation properties of compressed sulphur hexaflouride are adversely affected by metallic particle contamination in practical gas insulated systems. The movement of such particles is random and the particles play a crucial role in determining the insulation behavior of GIS. A Three-phase enclosure-type gas insulated bus (GIB) has widely been applied to minimize the installation space of a substation. To determine the particle trajectories in a three-phase common enclosure Gas ...

Kamakshaiah, S.; Amarnath, J.; Venu Gopala Rao, M.

2008-01-01

345

Energy Technology Data Exchange (ETDEWEB)

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.

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

346

Genetic Algorithm based Steady-State Analysis of Three-Phase Self-Excited Induction Generators

This paper presents a genetic algorithm based steady-state analysis of a three-phase self-excited induction generator (SEIG) for wind energy conversion. A generalized mathematical model based on inspection is developed for a three-phase induction generator for steady-state analysis. The proposed mathematical model is quite general in nature and can be implemented for any type of load such as resistive or reactive load. The proposed model completely avoids the tedious work of segregating rea...

S. Singaravelu,; Sasikumar, S.

2012-01-01

347

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

348

A Novel Unit Power Factor Rectifier Based on Three-phase Digital PLL

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 ...

Xuegui Zhu; Zhihong Fu; Xiangfeng Su

2013-01-01

349

Towards assessing online uncertainty for three-phase flow metering in the oil and gas industry

A new three-phase (oil/water/gas) flow metering system has been developed for use in the oil and gas industries, based on Coriolis mass flow metering. To obtain certification for use in the Russian oil and gas industries, trials have taken place at the UK and Russian national flow laboratories, NEL in Glasgow and VNIIR in Kazan, respectively. The metrology of three-phase flow is complex, and the uncertainty of each measurement varies dynamically with the operating point, as ...

Henry, M. P.; Tombs, M. S.; Zhou, F. B.

2014-01-01

350

Diagnosis of Three-Phase Electrical Machines Using Multidimensional Demodulation Techniques

This paper deals with the diagnosis of three-phase electrical machines and focuses on failures that lead to stator- current modulation. To detect a failure, we propose a new method based on stator-current demodulation. By exploiting the configuration of three-phase machines, we demonstrate that the demodulation can be efficiently performed with low-complexity multidimensional transforms such as the Concordia transform (CT) or the principal component analysis (PCA). From a practical point of v...

Choqueuse, Vincent; Benbouzid, Mohamed; Amirat, Yassine; Turri, Sylvie

2012-01-01

351

Single phase inverter for a three phase power generation and distribution system

A breadboard design of a single-phase inverter with sinusoidal output voltage for a three-phase power generation and distribution system was developed. The three-phase system consists of three single-phase inverters, whose output voltages are connected in a delta configuration. Upon failure of one inverter the two remaining inverters will continue to deliver three-phase power. Parallel redundancy as offered by two three-phase inverters is substituted by one three-phase inverter assembly with high savings in volume, weight, components count and complexity, and a considerable increase in reliability. The following requirements must be met: (1) Each single-phase, current-fed inverter must be capable of being synchronized to a three-phase reference system such that its output voltage remains phaselocked to its respective reference voltage. (2) Each single-phase, current-fed inverter must be capable of accepting leading and lagging power factors over a range from -0.7 through 1 to +0.7.

Lindena, S. J.

1976-01-01

352

A pulse width modulation (PWM) scheme for multilevel inverters is proposed. The proposed PWM scheme generates the inverter leg switching times, from the sampled reference phase voltage amplitudes and centres the switching times for the middle vectors, in a sampling interval, as in the case of conventional space vector PWM (SVPWM). The SVPWM scheme, presented for multilevel inverters, can also work in the overmodulation range, using only the sampled amplitudes of reference phase voltages. The ...

Kanchan, Rs; Baiju; Mohapatra, Kk; Ouseph, Pp; Gopakumar, K.

2005-01-01

353

We develop miniature high-voltage sources from polymer solar cells (PSCs) with charge-transporting molybdenum oxide (MoOx) integrated in a serial architecture through sacrificial layer (SL)-assisted patterning. The MoOx layer, being patterned by the lift-off process of the SL of a hydrophobic fluorinated-polymer, as a hole transporting layer plays a critical role on the reduction of the dark current and the increase of a high open circuit voltage of an integrated PSC array. The underlying mechanism lies primarily on the elimination of the lateral charge pathways in the MoOx layer in the presence of the electrode interconnection. Two miniature voltage sources consisting of 20 PSCs and 50 PSCs are demonstrated in the operation of a liquid crystal display and an organic field-effect transistor, respectively. Our SL-assisted integration approach will be directly applicable for implementing the self-power sources made of the PSCs into a wide range of the electronic and optoelectronic devices.

Cho, Seong-Min; Keum, Chang-Min; Park, Hea-Lim; Kim, Min-Hoi; Bae, Jin-Hyuk; Lee, Sin-Doo

2014-04-01

354

A new method for the experimental determination of three-phase relative permeabilities

International Nuclear Information System (INIS)

Petroleum reservoirs under primary, secondary or tertiary recovery processes usually experience simultaneous flow of three fluids phases (oil, water and gas). Reports on some mathematical models for calculating three-phase relative permeability are available in the Literature. Nevertheless, many of these models were designed based on certain experimental conditions and reservoir rocks and fluids. Therefore, special care has to be taken when applying them to specific reservoirs. At the laboratory level, three-phase relative permeability can be calculated using experimental unsteady-state or steady state methodologies. This paper proposes an unsteady-state methodology to evaluate three-phase relative permeability using the equipment available at the petrophysical analysis Laboratory of the Instituto Colombiano del Petroleo (ICP) of Ecopetrol S.A. Improvements to the equipment were effected in order to achieve accuracy in the unsteady-state measurement of three-phase relative permeability. The target of improvements was directed toward to the attainment of two objectives:1) the modification of the equipment to obtain more reliable experimental data and 2) the appropriate interpretation of the data obtained. Special attention was given to the differential pressure and uncertainty measurement in the determination of fluid saturation in the rock samples. Three experiments for three-phase relative permeability were conducted using a sample A and reservoir rock from the Colomsample A and reservoir rock from the Colombian Foothills. Fluid tests included the utilization of synthetic brine, mineral oil, reservoir crude oil and nitrogen. Two runs were conducted at the laboratory conditions while one run was conducted at reservoir conditions. Experimental results of these tests were compared using 16 mathematical models of three-phase relative permeability. For the three-phase relative permeability to oil, the best correlations between experimental data and tests using Blunt, Hustad Hasen, and Baker's models were obtained at oil saturations between 40% and 70%

355

...Low- and medium-voltage circuits serving...or mobile three-phase alternating current...Low- and medium-voltage circuits serving...or mobile three-phase alternating current...Low- and medium-voltage circuits supplying...or mobile three-phase alternating...

2010-07-01

356

The comparing results of carcinoma between three-phase and delayed whole body bone scan

International Nuclear Information System (INIS)

Purpose: Three phase bone scan is an imaging technology in nuclear medicine, which composed of blood flow phase, blood pool phase and delayed phase and the last one is often performed in routine works in department of nuclear medicine. The purpose of this study is to evaluate the merit of three-phase bone scan.Methods: In this study, we chose 54 patients who were having an regional pain which caused by benign or malignant carcinoma that diagnosed by CT, X-ray, ECT, MRI or other examinations. The imaging were acquired simultaneously from both anterior and posterior views, after a bolus injection of 1110 MBq technetium-99m-labelled methylene diphosphonate (MDP), blood phase contains 20 frame sand 3 seconds per frame, blood pool phase contains 5 frames and 1 minute per frame, delayed phase was performed 2.5 hour later. According to the results of three-phase bone scan, the patients were divided into 2 groups: normal and abnormal groups. The abnormal group includes early phase positive,delay positive and all three phase positive sets. The comparing among the 3 sets were analyzed by chi-square test and other statistic means.Results: There were 54 patients who had suffered lung cancer, breast cancer and other cancer,involved in this study, 34 males and 20 females, ranged age 17 to 88 years, were normal in 15 cases,positive in 22 cases, the results in delayed phase were positive in 9 cases, blood flow and blood pool phase showed blood flow changes in 4 cases and soft tissue d flow changes in 4 cases and soft tissue tumors were seen in 4 cases. Three phase bone scan was more sensitive than delayed whole body bone scan in detecting the abnormal sites (p0.05) The sensitivity of detecting tumors in blood flow and blood pool phase,delayed phase were respectively lower than in three phase bone scan (p<0.001).Conclusion: It is more sensitivity of detecting tumor lesions in three phase bone scan than in delayed phase whole body bone scan and the changes of blood flow and soft tissue can be seen in three phase bone scan. So it is more suitable way to improve the sensitivity of detecting abnormal sites in three-phase bone scan. (authors)

357

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)

358

Early Hepatocellular Carcinoma: Three-Phase Helical CT Features of 16 Patients

International Nuclear Information System (INIS)

To evaluate the three-phase helical CT features of early hepatocellular carcinomas, based on the new Japanese classification. Over the course of an eight-year period, we collected 16 pathologically proven early hepatocellular carcinomas from 16 patients having undergone a three-phase helical CT prior to surgery. The three-phase CT images were acquired at 20 35 sec (arterial phase), 70 sec (portal phase), and 180 sec (equilibrium phase) from the beginning of intravenous injection of contrast material. All the CT images were retrospectively analyzed by two radiologists in consensus, based on their description of morphologic (size, margin, fibrous capsule and mosaic pattern) and enhancement patterns of tumors. Only seven (44%) of the 16 early hepatocellular carcinomas having undergone a CT were described (mean diameter, 1.2 cm; range, 0.4 2.5 cm). All the tumors had an ill-defined margin with no fibrous capsule. The mosaic pattern was found in only one tumor. Only three (43%) of the seven tumors detected on CT were hyperattenuating during the arterial phase. The four remaining tumors (25%) were hypoattenuating throughout the three phases. Despite the higher resolution provided by the three phase scans, the contrast-enhanced CT provides only limited detection of the variable morphologic and enhancement features of early hepatocellular carcinomas

359

Two- and three-phase mixing in a concentric draft tube gas-lift fermentor.

Two- and three-phase mixing studies were carried out in a 44-L concentric draft tube gas-lift fermentor. It was proposed to use the fermentor for the production of solvents using immobilized bacteria. Bubble size, gas holdup, liquid velocities, circulation, and mixing times were determined for various superficial gas velocities in distilled water, starch, carboxymethyl cellulose, and ethanol solutions. The observed trends for two phase mixing were similar to other studies but the results were found to be more sensitive to liquid properties. This was possibly due to the large value of downcomer to riser area used in this study. Mixing in three phases highlighted the difficulty in predicting the effect of adding solids to the gas-liquid system. Results showed that the gas-lift fermentor was ideally suited to dealing with three phases but more work is necessary before accurate models can be developed to account for the effect of solids. PMID:18600726

Kennard, M; Janekeh, M

1991-12-20

360

Adaptive nonlinear control of single-phase to three-phase UPS system

Directory of Open Access Journals (Sweden)

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.

Kissaoui M.

2014-01-01

361

Chaotic Recurrence Analysis of Oil-Gas-Water Three-phase Flow in Vertical Upward Pipe

Directory of Open Access Journals (Sweden)

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.

Ling-Fu Kong

2011-01-01

362

Proposed Method for Shoot-Through in Three Phase ZSI and Comparison of Different Control Techniques

Directory of Open Access Journals (Sweden)

Full Text Available This paper presented the new methodology for different control techniques applied to three phase Z-source inverter for minimisation of switching losses. The procedure for proposed control techniques and its effects on the performance of operation of three phase Z-source inverter are analyzed. The graphs for voltage gain and voltage stress are drawn for different control methods. The flow-chart for the symmetrical and unsymmetrical control techniques for creating pulse signals for switches of three phase inverter are shown. All the methods are studied and compared with each other. The Total harmonic distortion (THD of output voltage of both the control methods has been analyzed using FFT analysis. The experiments done and the results shown for capacitor voltage, load current and load line voltage for simple boost and constant boost control techniques are presented using MATLAB/ Simulink.

Byamakesh Nayak

2014-07-01

363

A Fully Equivalent Global Pressure Formulation for Three-Phase Compressible Flow

We introduce a new global pressure formulation for immiscible three-phase compressible flows in porous media which is fully equivalent to the original equations, unlike the one introduced in \\cite{CJ86}. In this formulation, the total volumetric flow of the three fluids and the global pressure follow a classical Darcy law, which simplifies the resolution of the pressure equation. However, this global pressure formulation exists only for Total Differential (TD) three-phase data, which depend only on two functions of saturations and global pressure: the global capillary pressure and the global mobility. Hence we introduce a class of interpolation which constructs such TD-three-phase data from any set of three two-phase data (for each pair of fluids) which satisfy a TD-compatibility condition.

Chavent, Guy

2009-01-01

364

Uncertainty Assessment of Interpolation-Based Three Phase Relative Permeability Models

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.

Ranaee, Ehsan; Giovanni, Porta; Monica, Riva; Alberto, Guadagnini

2013-04-01

365

THRIVE : a data reduction program for three-phase PDV/PDI and VISAR measurements.

Energy Technology Data Exchange (ETDEWEB)

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.

Jones, Scott Christopher; Dolan, Daniel H.

2008-06-01

366

Phase holdups in three-phase fluidized beds in the presence of disc promoter

Energy Technology Data Exchange (ETDEWEB)

Three-phase fluidized beds are found to have wide applications in process industries. The present investigation essentially comprises of the studies on gas holdup, liquid holdup and bed porosity in three-phase fluidized beds with coaxially placed disc promoter. Holdup data were obtained from bed expansion and pressure drop measurements. Analysis of the data was done to elucidate the effects of dynamic and geometric parameters on gas holdup, liquid holdup and bed porosity. Data were correlated and useful equations were obtained from empirical modeling. (author)

Murty, M.S.N. [Department of Chemical Engineering, GVP College of Engineering, Visakhapatnam 530 048 (India); Ramesh, K.V.; Venkateswarlu, P. [Department of Chemical Engineering, Andhra University, Visakhapatnam 530 003 (India); Prabhakar, G. [Department of Chemical Engineering, Sri Venkateswara University, Tirupati 517 502 (India)

2011-02-15

367

Stator Winding Fault Diagnosis Of Three-Phase Induction Motor By Park’s Vector Approach

Through this paper issue of on-line detection of short winding fault in three-phase induction motors is presented, and a technique, based on the computer-aided monitoring of the stator current Park’s Vector, is proposed. The park's vector model is realized by employing Virtual instrumentation. The Virtual Instrumentation is acquired by programming in Lab-view software. Laboratory analysis was performed on a 0.5 hp three phase induction motor. The motor was originally evaluated under optimum...

S M Shashidhara, Dr P. S. Raju

2013-01-01

368

Field results on developed three-phase four-wire shunt active power filters

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...

Pinto, J. G.; Neves, Pedro; Gonc?alves, Domingos; Afonso, Joa?o L.

2009-01-01

369

Fast Unbalanced Three-phase Adjustment Base on Single-phase Load Switching

To balance three-phase loads in distribution network with abundant of single-phase loads, a new wiring method and three-phase loads adjustment policy was proposed in this paper. In the wiring method, a single-phase load was connected with phase A, B and C of trunk line by a controller. When the load of trunk line was unbalanced, the controller will switch the connected single-phase loads from one phase to another to balance it. The minimum count of loads adjustment algorithm and the most bala...

Yanwei Zheng; Lisheng Zou; Jian He; Yongyi Su; Zhiquan Feng

2013-01-01

370

Area Based Approach for Three Phase Power Quality Assessment in Clarke Plane

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents an area-based approach for electric power quality analysis. Some specific reference signals have been defined and areas formed by the real power system data with the reference signal have been calculated wherefrom contributions of fundamental waveform and harmonic components have been assessed separately. Active power, reactive power and total harmonic distortion factors have been measured. Clarke transformation technique has been used for analysis in three-phase system, which has reduced the computational effort to a great extent. Distortion factors of individual phase of a three-phase system have also been assessed.

S. CHATTOPADHYAY

2008-03-01

371

A Novel Three-phase Rectifier Based on Improved PID Control Algorithm

The three-phase rectifier based on traditional PID control algorithm can improve its harmonic effect, and increase its power factor, but it can’t overcome the problems of selection difficulty of the PID parameters and can realize the online self-turning function of the PID parameters. In order to deal with the questions, the three phase rectifier based on neural network PID control algorithm is designed in this paper. In this paper, the PID parameters of the novel rectifier can realize t...

Zhang Kai; Jiang Jing; Zhang Shutuan

2013-01-01

372

On Determination of Arc Currents in Three-Phase Single-Chamber Plasma Generators

Two methods of determining the arc currents in three-phase single-chamber alternating-current generators are presented. In the first method, the current traversing one of the electrode spacings in a three-phase network is disregarded. The second method is based on the consideration of the general mechanisms of the gas flows around arcs. In this method, the volt-ampere characteristic of an arc discharge is constructed from the calculated values of the voltage drop across the arc that are closest to the measured values of this drop.

Kovshechnikov, V. B.; Antonov, G. G.; Ufimtsev, A. A.; Surov, A. V.

2014-05-01

373

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.

Piyarat, Wekin; Kinnares, Vijit

374

DEFF Research Database (Denmark)

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.

Xiao, Lei; Huang, Shoudao

2013-01-01

375

Controlador repetitivo para inversores PWM com referência de freqüência variável

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese 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.

Leandro, Michels; Márcio, Stefanello; Hilton A., Gründling.

2009-09-01

376

Energy Technology Data Exchange (ETDEWEB)

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.

Garza Macias, Anibal [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1988-12-31

377

A predictive control algorithm for an active three-phase power filter

Directory of Open Access Journals (Sweden)

Full Text Available The paper deals with grid connection circuits for active filters, structures of active power filter control systems, and methods based on full capacity components determination. The existing structures of active power filter control and control algorithm adjustment for valve commutation loss reduction are analyzed. A predictive control algorithm for an active three-phase power filter is introduced.

R.V. Vlasenko

2014-09-01

378

Three-phase diode rectifiers with low harmonics current injection methods

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.

Pejovic, Predrag

2007-01-01

379

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.)

380

Three-phase scintigraphy in epicondylitis of the lateral lower humerus

Energy Technology Data Exchange (ETDEWEB)

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.

Koppers, B.; Riel, K.

1982-08-01

381

Directory of Open Access Journals (Sweden)

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.

Angelo A. Beltran Jr

2014-04-01

382

High Frequency Soft Switching Of PWM Boost Converter Using Auxiliary Resonant Circuit

Directory of Open Access Journals (Sweden)

Full Text Available This thesis presents High frequency Soft Switching DC-DC boost Converter. The circuit consists of a general Boost Converter with an additional resonant circuit which has a switch, inductor, capacitor and a diode.In general Boost Converter circuits have snubber circuits where switching losses are dissipated in external passive resistors; which is known as hard switching. As the switching frequency of PWM converters is increased its switching losses and conduction losses also increases. This restricts the use of PWM technique. New Zero Voltage Transition-Zero Current Transition (ZVT-ZCT PWM converter equipped with the snubber provides the most desirable features of both ZVT and ZCT converters presented previously. Moreover all semiconductors devices operate with soft switching and hence losses are reduced.

C. P. Sai Kiran

2014-10-01

383

Area Equalization PWM Techniques for Single-Phase Full Bridge Inverter with Fluctuating DC Input

Directory of Open Access Journals (Sweden)

Full Text Available An extension of equal sampling technique (EST based pulse width modulation (PWM is presented for the single-phase inverter to reduce lower order harmonics caused by the fluctuating dc input. In the EST, which has been proposed earlier for constant dc, the width of PWM pulses is determined by making the area of the PWM signal equal to the area under the sampled reference waveform. The concept of equal area criterion equally applicable for fluctuating dc input with required modifications of the governing equations. Simulation results show that EST is triumphant in reducing lower order harmonics. Potential applications of the proposed technique are in fixed and variable frequency inverters for power supplies and ac motor drives which experience voltage ripple in the dc-link either when fed from a weak ac system or when insufficient filtering is employed.

G Pavankumar

2007-01-01

384

EVALUATION OF VARIOUS UNIPOLAR MULTICARRIER PWM STRATEGIES FOR FIVE LEVEL FLYING CAPACITOR INVERTER

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the comparison of unipolar multicarrier Pulse Width Modulation (PWM techniques for the Flying Capacitor Multi Level Inverter (FCMLI. Due to switch combination redundancies, there are certain degrees of freedom to generate the five level AC output voltage. This paper presents the use of Control Freedom Degree (CFD combination. The effectiveness of the PWM strategies developed using CFD are demonstrated by simulation and experimentation. The results indicate that the multilevel inverter triggered by the developed USHPWM strategy exhibits reduced harmonics. PWM strategies developed are implemented in real time using dSPACE/Real Time Interface (RTI. The simulation and experimental output closely match with each other validating the strategies presented.

B. SHANTHI

2012-06-01

385

Synchronization of the distributed PWM carrier waves for modular multilevel converters

DEFF Research Database (Denmark)

The half-bridge modular multilevel converter has proven itself to be a suitable solution for HVDC application. In order to achieve high modularity and fault tolerance, distributed control strategy is one possible solution and is discussed in this paper. When distributed control strategy is used, there is a central controller and a local controller in each sub-module (SM). A problem appears when implementing the modulation using this type of control strategy; this is the lack of synchronization between the internal clocks of the different submodules controllers of the MMC. This will cause a drift between the PWM outputs of each sub-module increasing the total harmonic distortion of the output voltage. This paper presents a solution to synchronize the PWM outputs of the MMC submodules using EtherCAT communication protocol focusing on phase shifted PWM modulation technique.

Burlacu, Paul Dan; Mathe, Laszlo

2014-01-01

386

Isolated PDM and PWM DC-AC SICAMs[Pulse Density Modulated; Pulse Width Modulated

Energy Technology Data Exchange (ETDEWEB)

In this report a class of isolated PDM and PWM DC-AC SICAMs is described, which introduce the audio reference only in the output stage. AC-DC power supply is implemented in its simplest form: diode rectifier followed by a medium-size charge-storage capacitor. Isolation from the AC mains is achieved using a high frequency (HF) transformer, receiving the HF voltage pulses from the input 'inverter' stage and transferring them to the output 'rectifier+inverter' stage, which can use either PDM or PWM. The latter stage is then interfaced to the load using an output low-pass filter. Each of the dedicated stages is discussed in detail. Measurements on the master/slave PWM DC-AC SICAM prototype are presented to help benchmarking the performance of this class of SICAMs and identify the advantages and drawbacks. (au)

Ljusev, P.

2004-03-15

387

Led spectral and power characteristics under hybrid PWM/AM dimming strategy

DEFF Research Database (Denmark)

In order to dim LEDs the pulse width modulation (PWM) or amplitude modulation (AM) dimming scheme is typically used. Previous studies show that these dimming schemes can have opposite effects on diodes peak wavelength shift. An experimental study was conducted to test the behavior of InGaN diodes and phosphor-converted white diodes under hybrid PWM/AM modulation. Feed forward control schemes that provide stable peak wavelength position during dimming and the ability to compensate the thermally induced color shifts and the decrease of the luminous flux are investigated.

Beczkowski, Szymon; Munk-Nielsen, Stig

2010-01-01

388

AC Motor Drive Fed by Renewable Energy Sources with PWM

Directory of Open Access Journals (Sweden)

Full Text Available In this fast aproaching nature of technology the ned of Electricity becomes a mandatory in developing technology. The ned of Electricity increases the power demand where the power demand met by the conventional sources of energy has some disadvantage of polution, this disadvantage can be decreased by the use of the Renewable energy sources like Fuel Cel and available solar energy. When a FUEL cel produces AC power, basicaly two stages are required for conversion first a bosting stage and second is inversion stage. In this paper the Bost inverter topology is achieved where in the conventional methods the normal DC - AC power conversion method is used where as in this paper the PWM based DC - AC inverter has ben used which is useful in reducing the harmonics in the output of the Inverter. The voltage controled output is produced in the bost inverter the curent controled output is taken from dc-dc bidirectional converter. The Fuel cel canot be relied as a whole so a Solar PV module is conected acros the Load so while the Sunlight days the PV arays generate power and in the night time the Fuel cel is used to generate power for the load. Since, the Fuel cel and PV arays can generate power in Partial load they are prefered than any other sources. When the output from the Solar PV aray is low or when the sunlight available is not eficient in generating the power a automatic switch over is provided in the junction betwen the Solar PV aray and Fuel cel so that whenever it hapens the switch automaticaly switch over to another source. The simulation results are presented to confirm the operational feature of the proposed system.

J. Pavalam

2014-01-01

389

Fracture healing: Quantitative three-phase bone scintigraphy as a prognostic factor

International Nuclear Information System (INIS)

Aim: Careful clinical examination and conventional radiography, together with other standard methods for evaluation of bone fracture healing, are frequently inconclusive. Furthermore, it is difficult to predict the complications of healing on the basis of clinical and radiographic findings only. Bone scintigraphy plays an important role in detecting bone fractures. This method is very sensitive, but not enough specific. The aim of this work was to evaluate the role of three-phase bone scintigraphy in the healing prognosis of long bone fractures. Material and Methods: We evaluated the three elements (perfusion, blood pool and static image) of three-phase bone scintigraphy in early prognosis of the course of fracture healing in patients with fractures of femur or tibia. Three-phase bone scintigraphy was performed in 73 patients. The patients were divided into 4 groups according to X-ray and clinical examination: 1) Non operated patients with stable fracture, 2) Operated patients with unstable fracture (infection), 3) Fractures with delayed union, 4) Patients with pseudoarthrosis. Using region of interest (ROI) method we compared the activity on the site of fracture with the activity on the symmetrical place in the healthy bone. The relative indices for each group of patients and for each element of three-bone scintigraphy were calculated in order to make possible the follow up of the fracture healing and to obtain data for prognosis and evaluation of possible complicatiosis and evaluation of possible complications. Results: The most valuable results were obtained by quantitative analysis of perfusion data immediately after trauma and 2-3 weeks later. Our results show a high diagnostic accuracy in identifying infection by perfusion scintigrams immediately after trauma. The perfusion indices obtained immediately and after 2-3 weeks could predict delayed union after the trauma. Quantitative analysis of blood pool phase gave no data of clinical significance in distinguishing various pathologies. Conclusion: Our results indicate that the three-phase bone scintigraphy is a useful method when complications of fracture healing are expected. In these cases radiography gives only a partial insight into the state of bone union, but no information about the healing process. So, the increasing use of three-phase bone scintigraphy is quite understandable. Nevertheless, as most of the fractures heal regularly, we would not advise the three-phase bone scintigraphy as a routine procedure

390

Simulation of a three-phase three-dimensional reacting flow in an FCC industrial riser

Energy Technology Data Exchange (ETDEWEB)

This study used a three-dimensional and three-phase flow model to predict the dynamic behavior of a fluid catalytic cracking (FCC) industrial reactor. It took into account heat transfer, feedstock vaporization and cracking reactions. The Eulerian/Eulerian-Lagrangian approach was used to simulate the dynamic three-phase flow inside the riser. The catalytic cracking reactions were predicted using the 4-lump model. A commercial CFD code (Fluent) was used to obtain the numerical data, and appropriate user defined functions were implemented to model the heterogeneous kinetics and the catalyst deactivation. Results show nonuniform tendencies inside the reactor, emphasizing the importance of a sophisticated model in FCC process predictions. (author)

Lopes, Gabriela Cantarelli; Rosa, Leonardo Machado da; Mori, Milton; Nunhez, Jose Roberto [Universidade Estadual de Campinas (FEQ/UNICAMP), SP (Brazil). Fac. de Engenharia Quimica], E-mails: gacleq@feq.unicamp.br, mori@feq.unicamp.br, leorosa@feq.unicamp.br, nunhez@feq.unicamp.br; Martignoni, Waldir Pedro [PETROBRAS, Rio de Janeiro, RJ (Brazil). Gerencia de Otimizacao], E-mail: martignoni@petrobras.com.br

2011-04-15

391

Application of Generalized Instantaneous Reactive Power Theory for Three-Phase Four-Wire System

Directory of Open Access Journals (Sweden)

Full Text Available In this paper a concept of generalized theory of instantaneous imaginary power is proposed for a three-phase four-wire system. Unlike instantaneous reactive power theory in which a complexmathematical transformation is used for controlling action of shunt active power filters. The proposed control strategy is simple and further to reduced its complexity the line current vector is decomposed into two orthogonal components without mathematical transformations. The developed control strategy has been tested for three-phase four-wire system feeding non-linear load. The obtained results show satisfactory performance for a number of actual system conditions such as load changing of non-linear load. The THD (total harmonic distortion on supply side with shunt active power filter complies with IEEE harmonic standard, which validates the satisfactory implementation of proposed theory.

Ajay Kumar Maurya

2012-12-01

392

Dynamic\tmodelling of catalytic three-phase reactors for hydrogenation and oxidation processes

Directory of Open Access Journals (Sweden)

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.

Salmi T.

2000-01-01

393

A Comparision of Three Phase 27 Level Inverter Scheme under No Load and Multiple Load Conditions

Directory of Open Access Journals (Sweden)

Full Text Available Multilevel inverters have been used in the industrial as well as the drive applications. Here three phase system of the 27 level inverter scheme with and without loads have been presented by combining the three single phase inverters of various and asymmetrical voltage ranges. Here capacitors, batteries may be used for multiple dc sources in order to achieve high voltage output. It is shown that by implementing the single phase model in the three phase system the harmonic content is lowered even in the loaded conditions than compared to the single phase system. The proposed method can be validated and simulation is carried out with the help of MATLAB/Simulink software.

C. Kannan

2014-12-01

394

Performance Evaluation of an Extended Gain Three-Phase Grid Connected Boost-inverter

Directory of Open Access Journals (Sweden)

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.

DR. A.ELSEROUGI

2013-05-01

395

Analysis of three-phase power-supply systems using computer-aided design programs

International Nuclear Information System (INIS)

A major concern of every designer of large, three-phase power-supply systems is the protection of system components from overvoltage transients. At present, three computer-aided circuit design programs are available in the Magnetic Fusion Energy (MFE) National Computer Center that can be used to analyze three-phase power systems: MINI SCEPTRE, SPICE I, and SPICE II. These programs have been used at Lawrence Livermore Laboratory (LLL) to analyze the operation of a 200-kV dc, 20-A acceleration power supply for the High Voltage Test Stand. Various overvoltage conditions are simulated and the effectiveness of system protective devices is observed. The simulated overvoltage conditions include such things as circuit breaker openings, pulsed loading, and commutation voltage surges in the rectifiers. These examples are used to illustrate the use of the computer-aided, circuit-design programs discussed in this paper

396

Deformation of an Elastic Substrate by a Three-Phase Contact Line

Young’s classic analysis of the equilibrium of a three-phase contact line ignores the out-of-plane component of the liquid-vapor surface tension. While it is expected that this unresolved force is balanced by the elastic response of the solid, a definitive analysis has remained elusive because of an apparent divergence of stress at the contact line. While a number of theories have been presented to cut off the divergence, none of them have provided reasonable agreement with experimental data. We measure surface and bulk deformation of a thin elastic film near a three-phase contact line using fluorescence confocal microscopy. The out-of-plane deformation is well fit by a linear elastic theory incorporating an out-of-plane restoring force due to the surface tension of the solid substrate. This theory predicts that the deformation profile near the contact line is scale-free and independent of the substrate elastic modulus.

Jerison, Elizabeth R.; Xu, Ye; Wilen, Larry A.; Dufresne, Eric R.

2011-05-01

397

Ranking of three-phase bone scintigraphy for early diagnosis of Sudeck's astrophy

International Nuclear Information System (INIS)

In a prospective study the value of the three-phase bone scintigraphy in the early diagnosis of Sudeck's atrophy was analysed. 137 patients with the clinical suspicion on Sudeck's atrophy in stage I were examined. By means of the clinical course and additional examinations (block response), pain experts confirmed the diagnosis separately. With the findings of hyperperfusion of all 5 phalanges, homogeneous hyperaemia of the affected hand or the foot and periarticular increased uptake of the whole extremity a reliable diagnosis of Sudeck's atrophy was possible. The sensitivity was 95.9%, the specificity 100%. With bone scintigraphy Sudeck's atrophy could be clearly differentiated from an inactivity atrophy. Three-phase bone scintigraphy is an excellent tool for the objective diagnosis of Sudeck's atrophy in stage I. (orig.)

398

Adaptive RBF Neural Network Control for Three-Phase Active Power Filter

Directory of Open Access Journals (Sweden)

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.

Juntao Fei

2013-05-01

399

Dynamic D-Q Axis Modeling Of Three-Phase Asynchronous Machine Using Matlab

Directory of Open Access Journals (Sweden)

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.

SHAKUNTLA BOORA, S.K AGARWAL, K.S SANDHU

2013-08-01

400

Simulation of Three Phase Three Level Rectifier Achieved by NPC Phenomenon

Directory of Open Access Journals (Sweden)

Full Text Available A novel topology of a three phase three level Rectifier achieve by NPC phenomenon is presented in this paper. Switches control by pulse width modulation technique used. The implementation is by using NPC (Neutral point controlling clamping. The input voltage is given to all three phases is 55 volt each and the output boost voltage we get up to 600volt. The final output is due to the two lower outputs at two capacitors and one common output (as we say three levels of rectifier. The voltage across these two capacitors (lower levels is about 300volt. And hence we are getting a common output, at third level of 600volt

Samuel William

2014-09-01

401

Modeling and control of three phase rectifier with electronic smoothing inductor

DEFF Research Database (Denmark)

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.

Singh, Yash Veer; Rasmussen, Peter Omand

2011-01-01

402

A New Soft-Switched Three-Phase Four-Wire Shunt Active Power Filter

Directory of Open Access Journals (Sweden)

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.

Mohammad Reza Moradian

2010-07-01

403

A novel process for extraction of edible oils. Enzyme assisted three phase partitioning (EATPP)

Energy Technology Data Exchange (ETDEWEB)

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)

Gaur, R.; Sharma, A.; Khare, S.K.; Gupta, M.N. [Indian Institute of Technology, New Delhi (India). Chemistry Department

2007-02-15

404

A novel process for extraction of edible oils: Enzyme assisted three phase partitioning (EATPP).

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, 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. PMID:16574406

Gaur, Ruchi; Sharma, Aparna; Khare, S K; Gupta, Munishwar Nath

2007-02-01

405

International Nuclear Information System (INIS)

The present thesis deals with the calculation of the thermodynamic equilibrium state of the three-phase system gas-solution-solid. It presents the essential mathematical formalisms that describe the interactions of solution-gas, solution-solution, solution-solid, and solution-solid matrix as well as the boundary conditions and side constraints for the application of these relationships according to current knowledge. These expressions are used in the newly developed computer model KOMPLEX3 by incorporating the gas and solid phases besides the liquid phase in the calculations. The three-phase model KOMPLEX3 is able to quantify interactions between basic chemical and/or physico-chemical processes. (orig./BBR)

406

Transient analysis of three-phase induction machine using different reference frames

Directory of Open Access Journals (Sweden)

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.

Vivek Pahwa

2009-10-01

407

Simulation study of three-phase induction motor with variations in moment of inertia

Directory of Open Access Journals (Sweden)

Full Text Available Transient performance of any electrical machine is greatly affected by sudden changes in its supply system, operating speed, shaft load including any variations in moment of inertia due to gear arrangement applications. D, q- axis modeling which is universally acceptable to determine such analysis may be adopted using stator reference frame/rotor reference frame/synchronously rotating reference frame. In this paper, rotor reference frame is used for the simulation study of three phase induction motor. MATLAB/SIMULINK based modeling is adopted to compare the transient performance of three-phase induction motor including main flux saturation with and without the moment of inertia (MOI of the system attached to the motor. Simulated results have been compared and verified with experimental results on a test machine set-up. A close agreement between the simulated and experimental results proves the validity of proposed modeling.

K. S. Sandhu

2009-08-01

408

Phase Angle Balance Control for Harmonic Filtering of A Three Phase Shunt Active Filter System

This paper proposes a new strategy for harmonic filtering of a three-phase shunt active filter system. The shunt harmonic filter's control objective is defined as: balance the phase angle of the input current with the phase angle of the line frequency component of the load current. This objective is achieved in discreet implementation without sensing the input voltages. The controller uses a phase shifting method on the sensed input current and then applies the resistor emulator type input cu...

Chattopadhyay, Souvik; Ramanarayanan, V.

2002-01-01

409

A variable frequency three phase inverter for use with Philips cryogenerators

International Nuclear Information System (INIS)

This report describes a solid state inverter designed to power the helium circulators on the cryogenerators used on the Rapid Cycling Vertex Detector at the Rutherford Laboratory. In these cryogenerators cold helium is pumped around the refrigeration loop by a small three phase induction motor. The motor requires a supply of 220 volts, 40 mA per phase, and varying in frequency between 200 and 300 Hz, depending on the length and general characteristics of the loop and transfer line. (author)

410

DETECTING STATOR AND ROTOR WINDING FAULTS IN THREE-PHASE INDUCTION MACHINES

The purpose of this work is to investigate the efficiency of existing methods for on-line fault detection when applied to three-phase induction motors, spc:cifically to test known theoretical calculations of harmonics developed by certain types of faults experimentally. The work involves the development of equipment and test procedures needed and research of existing methods of fault detection. The experiments are cor~ductedb y planting a fault in a test induction machine and then performing ...

Robertson, Jeffrey C.; Ong, Chee Mun

1995-01-01

411

Comparative Study of Controller Design for Four Quadrant Operation of Three Phase BLDC Motor

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...

Suganya, Ms K.

2014-01-01

412

Secondary Voltage Unbalance Compensation for Three-Phase Four-Wire Islanded Microgrids

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...

Tang, Fen; Zhou, Xiao; Meng, Lexuan; Guerrero, Josep M.; Vasquez, Juan Carlos

2014-01-01

413

Measuring the three-phase contact angle of nanoparticles at fluid interfaces.

We report a generic technique to image and study the wettability of spherical nanoparticles adsorbed at liquid surfaces and demonstrate that nanoparticle monolayers can be imprinted at air-water and oil-water interfaces and their three-phase contact angle at the original liquid interface can be determined by an atomic force microscopy scan on a replica of the interface; the technique is tested using four different types of nanoparticles, the smallest one having a radius of 37 nm. PMID:20023808

Arnaudov, Luben N; Cayre, Olivier J; Cohen Stuart, Martien A; Stoyanov, Simeon D; Paunov, Vesselin N

2010-01-14

414

Low interfacial tensions in three-phase systems obtained with oil-water surfactant mixtures

We have studied the quaternary mixture brine-toluene-SDS-butanol, in the domain where it gives three phases, a microemulsion in contact with an organic and an aqueous phase, and measured three low interfacial tensions ?mo, ?XXX and ?ow. We find ?ow stays equal to the largest of the two others and conclude that the origin of low interracial tensions between the microemulsion and organic or aqueous phases are due to different phenomena.

Pouchelon, A.; Meunier, J.; Langevin, D.; Chatenay, D.; Cazabat, A. M.

1980-12-01

415

Directory of Open Access Journals (Sweden)

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.

Tine L. Vandoorn

2013-12-01

416

Design of Nine Level Inverter Topology for Three Phase Induction Motor Drives

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...

Sudhakar, G.; Prabhakaran, S.

2014-01-01

417

A New Soft-Switched Three-Phase Four-Wire Shunt Active Power Filter

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 thre...

Mohammad Reza Moradian; Khalil Rahimi; Majid Pakdel

2010-01-01

418

Adaptive RBF Neural Network Control for Three-Phase Active Power Filter

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...

Juntao Fei; Zhe Wang

2013-01-01

419

Direct control strategy for a four-level three-phase flying-capacitor inverter

A direct predictive control strategy is proposed for a three-phase four-level flying-capacitor (FC) inverter in this paper. The balancing of the FC voltages, a challenge in applications with small capacitors and low switching frequencies, is done without any modulation, simply using tables calculated offline. These allow the realization of fast-dynamics output currents with reduced dv/dt in the output voltages and reduced switching frequencies. Moreover, no interharmonics are created when ope...

Defay?, Francois; Llor, Ana-maria; Fadel, Maurice

2010-01-01

420

A new three-phase doubly salient permanent magnet machine for wind power generation

This paper presents a new three-phase 12/8-pole doubly salient permanent-magnet (DSPM) machine for application to wind power generation. The key is to design and analyze the proposed DSPM generator, namely, the design of a new machine structure to achieve high power density and high robustness and the device of system operation to attain high efficiency. By using finite element analysis, the static characteristics of the proposed generator are given. Hence, the evaluation of system performanc...

Fan, Y.; Chau, Kt; Cheng, M.

2006-01-01

421

Comparison of single and three-phase permanent magnet motor drives

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...

Santander, Eduardo; Ben Ahmed, Hamid; Multon, Bernard; Soulard, Juliette; Rakotovao, M.; Barrere, Franck

1998-01-01

422

Controlling a Four-Quadrant Brushless Three-Phase dc Motor

Control circuit commutates windings of brushless, three-phase, permanent-magnet motor operating from power supply. With single analog command voltage, controller makes motor accelerate, drive steadily, or brake regeneratively, in clockwise or counterclockwise direction. Controller well suited for use with energy-storage flywheels, actuators for aircraft-control surfaces, cranes, industrial robots, and other electromechanical systems requiring bidirectional control or sudden stopping and reversal.

Nola, F. J.

1986-01-01

423

Problem statement: With emphasis on a cleaner environment and efficient operation, vehicles today rely more and more heavily on electrical power generation for success. Approach: Mathematical modeling the components of the HEV as the three phase induction motor couple to DC motor in hybrid electric vehicle was introduced. The controller of Induction Motor (IM) was designed based on input-output feedback linearization technique. It allowed greater electrical generation capacity a...

Zulkarnain Lubis; Abdalla, A. N.; Mortaza; Ruzlaini Ghon

2009-01-01

424

Design and Research on the LCL Filter in Three-Phase PV Grid-Connected Inverters

Aiming at the problem of filtering in the three-phase PV grid-connected inverters, the mathematics models for L filter and LCL filter are established. The values of capacitances and inductances are calculated by analyzing the related constraint conditions for the main parameters of LCL filter. There are two ways to increase the value of damping resistor of the filter capacitor. The impacts on the stability and filtering property, in both ways, are analyzed. The simulation result indicated tha...

Xu Renzhong; Xia Lie; Zhang Junjun; Ding Jie

2013-01-01

425

Electromagnetic field in a cryoturbogenerator in the presence of an abrupt three-phase short circuit

International Nuclear Information System (INIS)

A solution is given for the nonsteady-state problem of the electromagnetic field in a cryoturbogenerator (CTG) with conducting shells; it is used for direct determination of the currents in the windings and shells of a cryogenic machine during transients. The course of the abrupt three-phase short-circuit process is analyzed for one variant of a large CTG in the presence of a shielding shell and an electrically conducting excitation-winding form

426

Modeling and Control of Three-Phase Shunt Active Power Filter

In this research the performance of a three-phase shunt active power filter (APF) using Model Reference Controller (MRC) has been compared with that using instantaneous active and reactive (p-q) theory. The novelty of this research lies in the application of MRC to generate the amplitude of the reference supply current required by the APF circuit and the successful implementation of the APF system for harmonic elimination. The entire system has been modeled using MATLAB 6.1 toolbox. Simulatio...

Moleykutty George; Basu, Kartik P.

2008-01-01

427

Activation of Alpha Chymotrypsin by Three Phase Partitioning Is Accompanied by Aggregation

Precipitation of alpha chymotrypsin in the simultaneous presence of ammonium sulphate and t-butanol (three phase partitioning) resulted in preparations which showed self aggregation of the enzyme molecules. Precipitation with increasing amounts of ammonium sulphate led to increasing size of aggregates. While light scattering estimated the hydrodynamic diameter of these aggregates in the range of 242–1124 nm; Nanoparticle tracking analysis (NTA) gave the value as 130–462 nm. Scanning elect...

Rather, Gulam Mohmad; Mukherjee, Joyeeta; Halling, Peter James; Gupta, Munishwar Nath

2012-01-01

428

Slip Compensation in Efficiency-Optimized Three-Phase Induction Motor Drive Systems

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...

Assbeihat, Jamal M.; Mohammad Alia; Rateb Issa; Hussein Sarhan

2011-01-01

429

Designing a Three Phase Inverter for a Permanent Magnet Synchronous Motor

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...

Dautermann, Lars

2013-01-01

430

A new Lagrangian formulation with complex currents is developed and yields a direct and simple method for modeling three-phase permanent-magnet and induction machines. The Lagrangian is the sum a mechanical one and of a magnetic one. This magnetic Lagrangian is expressed in terms of rotor angle, complex stator and rotor currents. A complexification procedure widely used in quantum electrodynamic is applied here in order to derive the Euler-Lagrange equations with complex sta...

Basic, Duro; Malrait, Franc?ois; Rouchon, Pierre

2008-01-01

431

Absorption in a three-phase fluidized bed II: Mass transfer investigations

The absorption of carbon dioxide in aqueous diethanolamine solutions was carried out in a three-phase fluidized bed with inert spherical packing. The rate of absorption was calculated on the basis of measuring the concentration change in the liquid phase on-line by a conductivity probe. It was shown that the Danckwerts plot method might be successfully used to simultaneously determine the effective interfacial area and both the gas and liquid-side mass transfer coefficients. While the gas-sid...

Pejanovi? Sr?an M.; Gari?-Grulovi? Radmila V.; Bozalo Predrag R.

2003-01-01

432

Transient analysis of three-phase induction machine using different reference frames

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...

Vivek Pahwa; Sandhu, K. S.

2009-01-01

433

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...

Aslan Sabahaldeen Jalal Abdi

2011-01-01

434

A Protection Scheme for Three-Phase Induction Motor from Incipient Faults Using Embedded Controller

This study presents a protection scheme for three-phase induction motor from incipient faults using embedded microcontroller. The induction motor experiences several types of electrical faults like over/under voltage, over load, phase reversing, unbalanced voltage, single phasing and earth fault. Due to these electrical faults, the windings of the motor get over heated which lead to insulation failure and thus reduce the life time of the motor. To analyze the behavior of induction motor durin...

Sudha, M.; Anbalagan, P.

2009-01-01

435

Simulation study of three-phase induction motor with variations in moment of inertia

Transient performance of any electrical machine is greatly affected by sudden changes in its supply system, operating speed, shaft load including any variations in moment of inertia due to gear arrangement applications. D, q- axis modeling which is universally acceptable to determine such analysis may be adopted using stator reference frame/rotor reference frame/synchronously rotating reference frame. In this paper, rotor reference frame is used for the simulation study of three phase inducti...

Sandhu, K. S.; Vivek Pahwa

2009-01-01

436

Stator Winding Fault Diagnosis Of Three-Phase Induction Motor By Park’s Vector Approach

Directory of Open Access Journals (Sweden)

Full Text Available Through this paper issue of on-line detection of short winding fault in three-phase induction motors is presented, and a technique, based on the computer-aided monitoring of the stator current Park’s Vector, is proposed. The park's vector model is realized by employing Virtual instrumentation. The Virtual Instrumentation is acquired by programming in Lab-view software. Laboratory analysis was performed on a 0.5 hp three phase induction motor. The motor was originally evaluated under optimum circumstances and Park's vector model was sketched. Subsequently, the short winding fault is reproduced in the motor. The motor was scrutinized again under erroneous condition and Park's vector model was sketched. Both plots were then scrutinized. It is ascertained that current park's vector pattern of healthy motor was perfect circle meanwhile current park's vector pattern under faulty condition was elliptical in shape. Experimental conclusion, derived by employing a distinct fault producing test rig, illustrate the efficiency of the suggested modus operandi, for determining the presence of short winding fault in running three-phase induction machines.

S.M.SHASHIDHARA, DR. P.S.RAJU

2013-07-01

437

Detection of stator winding faults in induction motors using three-phase current monitoring.

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

Sharifi, Rasool; Ebrahimi, Mohammad

2011-01-01

438

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

439

Energy Technology Data Exchange (ETDEWEB)

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 ({delta}) between the generator creating the power and the motor acting as a load. Thus, we expect that the transient stability deteriorates.

Cho, Y.S. [Dept. of Electrical Eng., Chosun University, Gwangju 501-759 (Korea, Republic of); Choi, H.S., E-mail: hyosang@chosun.ac.k [Dept. of Electrical Eng., Chosun University, Gwangju 501-759 (Korea, Republic of); Jung, B.I. [Dept. of Electrical Eng., Chosun University, Gwangju 501-759 (Korea, Republic of)

2010-11-01

440

Directory of Open Access Journals (Sweden)

Full Text Available This work presents the comparative study of the different PWM techniques to reduce the common-mode voltage (CMV at the output of neutral point diode clamped inverter for variable speed drives. Here the comparative study is done by the phase opposition disposed (POD, sinusoidal pulse width modulation (SPWM, phase disposition (PD, phase shift (PS space vector modulation (SVM techniques are proposed. A good trade-off between the quality of the output voltage and the partial magnitude of the CMV is achieved in this work. The scheme is proposed for three-level inverter. This work realizes the implementation of Three-level diode clamped MLI for three-phase (Y-? induction motor with the implementation of a space vector modulation technique without any additional control algorithm to reduce CMV within the range + Vdc/6. The Simulation with a 1HP induction motor drive system is setup in Matlab-2011b and the same results validated effectively by hardware – FPGA-SPARTEN III processor and its shows that the CM voltage is effectively reduced and the maximum output voltage is not affected.

Bharati Raja

2012-12-01

441

This paper establishes a mathematical model of induction machine connected to a frequency inverter necessary to adjust the electric motor drive. The mathematical model based on the Park's theory allows the analysis of the whole spectrum (electric car – frequency inverter) to drive the electric trolley bus made on ASTRA Bus Arad (Romania). To remove higher order harmonics, the PWM waveform of supply voltage is used, set in the general case. Operating characteristics of elec...

Boci?i, Liviu S.; VALENTIN MÜLLER

2013-01-01

442

DEVELOPMENT OF DIRECT TORQUE CONTROL MODELWITH USING SVI FOR THREE PHASE INDUCTION MOTOR

Directory of Open Access Journals (Sweden)

Full Text Available Direct torque control method is one of the best control strategies which allow a torque control in steady state and transient operation of induction motor. The main aim of direct torque control strategies is to effectively control the torque and flux of induction motor. Direct torque control method made the motor more accurate and fasttorque control, high dynamic speed response and simple to control. This paper present the principle of the direct torque control for voltage source inverter fed induction motor drive, and switching table, amplitude selection of the hysterics band of torque and flux. and also this method based on space vector modulation And its considered as an alternative to field oriented control technique. direct torque control methods is the first technology to control the ‘real’ motor control variable of torque and flux. and its has also more advantage such as it not required a feedback device and also not need external excitation. The performance of direct torque controlmethod has been demonstrated by simulation using a simulation package in matlab.

MUKESH KUMAR ARYA

2011-08-01

443

Performance Analysis of Fuzzy Flatness Based Speed Control of Three Phase Induction Motor

Directory of Open Access Journals (Sweden)

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.

C.SASIKUMAR, DR. C.MUNIRAJ

2013-05-01

444

Simulation Model of Space Vector Modulated Control Matrix Converter-fed Induction Motor

Matrix converters as induction motor drivers have received considerable attention in recent years because of its good alternative to Voltage Source Inverter Pulse Width Modulation (VSI-PWM) converters. This study focus on developing a mathematical model for a Space Vector Modulated (SVM) direct controlled matrix converter. The mathematical expressions relating the input and output of the three phase matrix converter are implemented by using MATLAB/SIMULINK. The duty cycles of the switches are...

Abdalla, A. N.; Ruzlaini Ghoni; Zakaria, N. F.

2011-01-01

445

Energy Technology Data Exchange (ETDEWEB)

This work introduces a new power supply by PWM, operating at constant frequency, with soft communication. The new topology uses only two active switches and absorbs the transformer leakage inductance. Besides, the soft communication takes place with no conduction loss penalty, in comparison with conventional hard switch PWM converters. Principle of operation, analysis, design and experimentation results taken from laboratory prototype rated at 400 W/48 v, 40 Khz, using IGBT are presented. (author) 10 refs., 71 figs.

Barbosa, Peter Mantovanelli

1993-10-01

446

DESIGN AND DEVELOPMENT OF GAS-LIQUID CYLINDRICAL CYCLONE COMPACT SEPARATORS FOR THREE-PHASE FLOW

Energy Technology Data Exchange (ETDEWEB)

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.

Dr. Ram S. Mohan; Dr. Ovadia Shoham

2001-04-30

447

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.

448

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

449

Energy Technology Data Exchange (ETDEWEB)

Bisphosphonate (BP) related osteonecrosis of the jaw (BRONJ) is a well known serious complication of BP treatment. This study was undertaken to evaluate the diagnostic usefulness of three phase bone scintigraphy in patients with BRONJ. Forty one patients (48 lesions)with clinically proven BRONJ (2 males, 39 females, age 74.3{+-}6.7 years)under went Tc 99m HDP bone scintigraphy. Visual interpretation and semiquantitative analysis of uptakes using lesion to contralateral uptake ratios during the blood pool phase (BUR)and during the osseous phase (OUR)were performed, and relations were sought between these and various clinical parameters. Three phase bone scintigraphy showed increased perfusion and blood pooling in 21 (63.6%)and 27 (81.8%)of 33 lesions, respectively. The osseous phase was positive for 45 (93.8%)of the 48 lesions. Of the four inflammatory clinical parameters of BRONJ [pus discharge, pain, swelling, and erythrocyte sedimentation rate (ESR)], patients with three or more parameters had more positive findings in vascular and blood pool phase images (p=0.033, p=0.027). By semiquantitative analysis, patients with a positive ESR had statistically higher BUR and OUR (both p<0.001). Higher stage BRONJ lesions had higher OUR than lower stage lesions (p=0.003). In addition, bone scintigraphy revealed three clinically covert BRONJ lesions without bone exposure, and four patients were up staged based on bone scintigraphy. Bone scintigraphy provides a relatively sensitive means of detecting BRONJ, so it was helpful for accurate BRONJ staging. Furthermore, Increased uptakes in vascular and blood pool phases of three phase bone scintigraphy were related to the inflammatory activity of BRONJ.

Hong, Chae Moon; Ahn, Byeong Cheol; Choi, So Young; Kim, Do Hoon; Lee, Sang Woo; Kwon, Tae Geon; Lee, Jaetae [Kyungpook National Univ., Daegu (Korea, Republic of)

2012-09-15

450

Three phase dynamic CT with double spiral CT: utility of determination of stomach cancer stage

International Nuclear Information System (INIS)

To evaluate the utility of three phases of spiral CT in the diagnosis of stomach cancer. Between August 1994 and March 1995, thirty eight patients with stomach cancer, demonstrated on spiral CT, underwent surgery. Twenty-eight cases were advanced and ten were early. There were 27 men, and 11 women, and their average age was 52.8 years old (33-77). After ingestion of 600-700ml of water, 120-140ml of nonionic contrast material was injected intravenously. Spiral CT scanning was performed in 10mm slice thickness and of 10mm/sec table speed. Three phase image were obtained at 25sec (arterial phase), 60-65sec (venous phase) and 4min (equilibrium phase) after the start of bolus injection. On each phase, CT findings were compared with pathologic results, and tumor detectibility, depth of tumor invasion and lymph node metastasis was analysed. Thirty of the 38 carcinomas (79%) were detected on the arterial phase, 33 (81%) on the venous phase and 30 (79%) on the equilibrium phase. Depth of tumor invasion was measured accurately in 27 of 38 cases (71%) : T1-4/10 (40%), T2-8/11 (73%), T3-13/15 (87%), T4-2/2 (100%). We overstaged one case of T1 as T2 and two cases of T2 as T3, and understaged one case of T2 as T1 and two cases of T3 as T2. Among the 16 enlarged lymph nodes larger than 8mm, 13 cases were positive on pathologic examination and the sensitivity was 65%. With three-phase spiral CT scanning, we obtained 71% accuracy of depth of tumor invasion. The venous phase is most usumor invasion. The venous phase is most useful for tumor detection and for determining depth of tumor invasion and lymph node metastasis

451

Next-generation three-phase inverters. Phase one annual report, 1996

Energy Technology Data Exchange (ETDEWEB)

The PV-MaT 4A subcontract addresses the cost effective manufacture of PV related end-products. Advanced Energy Systems Inc. (AES Inc.) has undertaken NREL contract No. ZAF-4-14271-10, {open_quotes}Next Generation Three Phase Inverter{close_quotes}, to combine leading industry skill with state-of-the-art technologies to realize cutting-edge PV inverter related products. To this end, in phase one of the PV-MaT contract, AES Inc. has made significant inroads toward establishing low cost manufacture of an intelligent controller PV-hybrid product.

Wesley, A; Wills, R [Advanced Energy Systems Inc., Wilton, NH (United States)

1997-07-01

452

Simulation of the Double-closed Loop Three-phase Asynchronous Variable Voltage Control System

Directory of Open Access Journals (Sweden)

Full Text Available When controlling the voltage and speed of the asynchronous motor, to expand the speed control range and reduce the speed fluctuation, the speed control system adopts two feedback control loops, i.e. the speed feedback control loop and the current feedback control loop. The principle and components of the double-closed loop three-phase asynchronous variable voltage control system are studied, and the simulation model and the test result based on MATLAB/Simulink are provided in this article through the system modeling and the parameter setup of the main circuit and the control circuit.

Shuhua Jiang

2011-09-01

453

Modeling of a three-phase reactor for bitumen-derived gas oil hydrotreating

A three-phase reactor model for describing the hydrotreating reactions of bitumen-derived gas oil was developed. The model incorporates the mass-transfer resistance at the gas-liquid and liquid-solid interfaces and a kinetic rate expression based on a Langmuir-Hinshelwood-type model. We derived three correlations for determining the solubility of hydrogen (H2), hydrogen sulfide (H2S) and ammonia (NH3) in hydrocarbon mixtures and the calculation of the catalyst effectiveness factor was include...

Chaco?n, R.; Canale, A.; Bouza, A.; Sa?nchez, Y.

2012-01-01

454

Secondary Voltage Unbalance Compensation for Three-Phase Four-Wire Islanded Microgrids

DEFF Research Database (Denmark)

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 microgri