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1

Control Strategy for Three Phase Voltage Source PWM Rectifier Based on the Space Vector Modulation

This paper proposes the space vector pulse width modulation (SVPWM) control scheme for three-phase voltage source PWM rectifier. The control system based on SVPWM includes two PI controllers which are used to regulate the AC currents and DC-link voltage. The proposed control can stabilize the minimum of the systems storage function at the desired equilibrium point determined by unity power factor and sinusoidal current on the AC side, and constant output voltage on the DC side. So the stab...

Miloud, Y.; Hartani, K.

2010-01-01

2

Control Strategy for Three Phase Voltage Source PWM Rectifier Based on the Space Vector Modulation

Directory of Open Access Journals (Sweden)

Full Text Available This paper proposes the space vector pulse width modulation (SVPWM control scheme for three-phase voltage source PWM rectifier. The control system based on SVPWM includes two PI controllers which are used to regulate the AC currents and DC-link voltage. The proposed control can stabilize the minimum of the systems storage function at the desired equilibrium point determined by unity power factor and sinusoidal current on the AC side, and constant output voltage on the DC side. So the stable state performance and robustness against the load?s disturbance of PWM rectifiers are both improved. The simulation result shows feasibility of this strategy.

MILOUD, Y.

2010-08-01

3

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, low total harmonic disto...

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

2012-01-01

4

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

5

High Performance FPGA Based Digital Space Vector PWM Three Phase Voltage Source Inverter

This paper focuses on the design of a low power and high performance FPGA based Digital Space Vector Pulse Width Modulation (DSVPWM) controller for three phase voltage source inverter. A new method is proposed to realize easy, accurate and high performance DSVPWM technique based on FPGA with low resource consumption and reduced execution time than conventional methods. Equations of SVPWM are relatively complicated and need a considerable time to execute on a typical microcontroller, therefore...

Bahram Rashidi; Mehran Sabahi

2013-01-01

6

High Performance FPGA Based Digital Space Vector PWM Three Phase Voltage Source Inverter

Directory of Open Access Journals (Sweden)

Full Text Available This paper focuses on the design of a low power and high performance FPGA based Digital Space Vector Pulse Width Modulation (DSVPWM controller for three phase voltage source inverter. A new method is proposed to realize easy, accurate and high performance DSVPWM technique based on FPGA with low resource consumption and reduced execution time than conventional methods. Equations of SVPWM are relatively complicated and need a considerable time to execute on a typical microcontroller, therefore a simple method is presented to minimize run time of instructions, e.g. the multiplication operation used in these equations is replaced by a proposed signed and unsigned shifter using 2 to 1 multiplexer unit. Total power consumption of controller is reduced to 37 mW at 100MHz clock frequency. The proposed DSVPWM technique algorithm was synthesized and implemented using Quartus II 9.1V and Cyclone II FPGA, to target device EP2C20F484C6. Also power is analyzed using XPower analyzer. Experimentation and results demonstrate that proposed method have high performance than other works.

Bahram Rashidi

2013-01-01

7

Three phase voltage source converter current analysis

International Nuclear Information System (INIS)

The proposed rectifier system consists of a three-phase diode bridge circuit as a main power circuit, A C reactors, and an additional circuit, which serves as an active filter with low switching frequencies and forced-commutation circuit for the diodes. These papers describe the operation principle, analysis of the waveforms of input voltage and current, the calculated of A C input current, multiple phase-shifted systems, and the experimental result. Avery conventional method was employed to analyze the input current equation; in that, the ripple output was neglected. The theory developed in this paper was verified twice; by calculation result and experiments. The calculated A C input the simple program using the algorithm of current equations calculated current waveforms presented in this paper. A switching circuit has been added to the diode rectifier, serving as an active filter and a forced-commutation circuit for diodes systems

8

A Comprehensive Study of Modulation Strategies for Three Phase Low Cost PWM Converter

A three phase voltage source converter using six power switches is a very important structure with wide variety of applications involving sophisticated ac drives, active power filters and power supplies etc. PWM voltage source inverters are also being incorporated in grid connected distributed power generating units to provide secure and reliable power to the utility grid. Due to the popularity of three-phase PWM converters there have been efforts in reducing the component count in these powe...

Bhattacharya, S.; Deb, P.; Biswas, Dr S. K.; Kar Chowdhury, Dr S.

2011-01-01

9

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

10

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

11

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

12

A Comprehensive Study of Modulation Strategies for Three Phase Low Cost PWM Converter

Directory of Open Access Journals (Sweden)

Full Text Available A three phase voltage source converter using six power switches is a very important structure with wide variety of applications involving sophisticated ac drives, active power filters and power supplies etc. PWM voltage source inverters are also being incorporated in grid connected distributed power generating units to provide secure and reliable power to the utility grid. Due to the popularity of three-phase PWM converters there have been efforts in reducing the component count in these power electronic converters as a cost effective substitute. These researches led to the development of four-switch converter topology. The four switches present in thepower circuit can be controlled in various ways to deliver the desired characteristics of sinusoidal source current, ability to deliver unity or even leading power factor, bidirectional power flow. To obtain such characteristics of the converter, various control techniques have been envisaged and implemented. The other PWM strategies have their own advantages and disadvantages. In this paper a study of the various control methods applied to four-switch PWM converter is presented are presented along with their performancecomparison.

S. BHATTACHARYA

2011-07-01

13

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

14

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

Directory of Open Access Journals (Sweden)

Full Text Available This papers deals with well – based mathematicalmodeling of variable speed alternator (Shaft Generator withPWM voltage source inverter used in ship. Detailed knowledge ofelectromagnetic characteristics of shaft generator is necessary fordesign complex ship's power system. Such knowledge isobtainable only by numerical simulations. The dynamic behaviorof shaft generators, SPWM voltage source inverter and theircontrollers during load variations are also discussed with the helpof MATLAB/SIMULINK. Elimination of harmonic contentsusing sinusoidal pulse width modulation also discussed here.

Sathish Kumar T

2012-07-01

15

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

16

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

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 c...

Gabriele Grandi; Jelena Loncarski

2013-01-01

17

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

18

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

19

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

20

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

21

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

22

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

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

Comparative Analysis of PWM Techniques for Three Level Diode Clamped Voltage Source Inverter

Multilevel inverters are increasingly being used in high-power medium voltage industrial drive applications due to their superior performance compared to conventional two-level inverters. Thre are a number of Pulse width modulation (PWM) techniques applied in recent years. The most widely applied PWM techniques are Sine Pulse Width Modulation (SPWM) and Space Vector Pulse Width Modulation (SVPWM). SPWM is the most simple modulation technique that can realize easily in analog circuit. Howe...

Zulkifilie Bin Ibrahim; Md. Liton Hossain; Ismadi Bin Bugis; Jurifa Mat Lazi; Nurazlin Mohd Yaakop

2014-01-01

25

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

26

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

27

Comparative analysis of SPWM and SVPWM control for three phase inverter

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 ...

Vinoth Kumar, K.; Prawin Angel Michael; John, Joseph P.; Suresh Kumar, S.

2010-01-01

28

Directory of Open Access Journals (Sweden)

Full Text Available ????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????PWM???????????????????????????????????

??

2014-12-01

29

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 us...

VISHNU MOHAN MISHRA; AMAR NATH TIWARI; NIKHLESH KUMAR SHARMA

2012-01-01

30

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

31

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the space vector definitions for the flux, current and the voltage in a three phase system. In this paper, a Space Vector PWM signal generation for a conventional 3-phase inverter by comparing the reference phase voltages with the reference voltage vector is presented. The sector in which the tip of the reference vector lies is found out and the proposed Space Vector-PWM (SVPWM method generates the inverter leg switching times, from the sampled reference phase voltage amplitudes in a sampling interval. Here Vdc is the conventional three phase inverter DC link voltage. To generate gating signals PIC ?- controller is used in addition to the interface circuit. The present work explains the gating signal generation and implementation by SVPWM using ?- controller.

B. Muralidhara,

2010-10-01

32

Research on Three-phase Voltage Type PWM Rectifier System Based on SVPWM Control

The fundamental principle of SVPWM is introduced in this study. The design on the structure of three-phase voltage type PWM rectifier system based on SVPWM control was also discussed. Then we calculate the DC capacitor and AC side inductance. The computer simulation tool MATLAB/Simulink is taken and the result is shown in the end. The result indicates that the design of such platform is feasible.

Haoran Shi; Wei Xu; Chenghua Fu; Yao Yang

2013-01-01

33

A new stationary frame control scheme for three-phase pulsewidth-modulation (PWM) rectifiers operating under unbalanced voltage dips conditions is proposed in this paper. The proposed control scheme regulates the instantaneous active power at the converter poles to minimize the harmonics of the input currents and the output voltage ripple. This paper's novelty is the development of a new current-reference generator implemented directly in stationary reference frame. This allows using proporti...

Roiu, Daniel; Tenconi, Alberto; Bojoi, Iustin Radu

2010-01-01

34

Comparative Analysis of PWM Techniques for Three Level Diode Clamped Voltage Source Inverter

Directory of Open Access Journals (Sweden)

Full Text Available Multilevel inverters are increasingly being used in high-power medium voltage industrial drive applications due to their superior performance compared to conventional two-level inverters. Thre are a number of Pulse width modulation (PWM techniques applied in recent years. The most widely applied PWM techniques are Sine Pulse Width Modulation (SPWM and Space Vector Pulse Width Modulation (SVPWM. SPWM is the most simple modulation technique that can realize easily in analog circuit. However, it has some drawbacks such as higher total harmonic distortion (THD, lower effective DC utilization and lower switching frequency. Space vector pulse width modulation (SVPWM is widely used because of their easier digital realization and better DC bus utilization and lower THD. The complexity is due to the difficulty in determining the reference vector location, on times calculation, and switching states selection. This paper presents a simple SVPWM algorithm for diode clamped three level inverters based on standard two-level SVPWM which can easily determine the location of reference vector, calculate the on-times, the selection of switching states. Three level diode clamped inverter (3LDCI using space vector modulation technique has been modeled and simulated using MATLAB/SIMULINK and Origin 6.1 with a passive R-L load that can be extended to any level. Simulation results are presented to verify the proposed SVPWM control in terms of THD. The results are compared with conventional sinusoidal pulse width modulation (SPWM where SVPWM shows better performance than SPWM in terms of THD.

Zulkifilie Bin Ibrahim

2014-07-01

35

A New PWM Modifying Technique for Reconstructing Three-phase Currents from DC Bus Current

Vector control is used to drive a DC brushless motor and generally needs current information. DC bus current detection is often adopted as a low cost method for reconstructing three-phase currents. PWM modifying techniques increase the DC pulse duration, thereby enabling easy detection of the DC bus current. However, these techniques have two problems: reducing a noise frequency and making the reconstructed current waveforms distorted by current ripple. In the techniques, modification signals are added to the three-phase voltage commands; the sum of the signals over a single cycle is zero. The authors examined several PWM modifying techniques from the points of view of noise and current distortion performance. One of the techniques had a good noise performance, and the frequency component of the noise was the same as the carrier frequency (fc). However, the reconstructed current waveforms were distorted. The total harmonic distortion (THD) varied from 1.7% to 4.1%. Another technique had a very poor noise performance, and the frequency component on the noise was one-fourth of fc. The authors developed a new PWM modifying method called “Half Pulse Shift”, which achieves the optimum noise and current distortion performance. The frequency component of the new method was two-thirds of fc, and the current waveforms were not distorted; the THD in the simulations and experiments was 0.5%-1.4% and 3.4%-3.6%, respectively.

Aoyagi, Shigehisa; Iwaji, Yoshitaka; Tobari, Kazuaki; Sakamoto, Kiyoshi

36

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

37

One-Stage High-Frequency-Isolated Three-Phase PWM Rectifier

The AC-DC converter, which has three-phase AC power as input and isolated DC power as output is used for the regulated DC power supply of the telecommunication power processing system for several kilowatt class applications. The conventional DC power supply for the telecommunication power system comprises a PWM rectifier with sinewave shaping input current unity power factor and a DC/DC converter connected to the PWM converter, which obtains DC48 V. Since power passes through these two power stage converters, the conversion power loss is difficult to provide high efficiency. In addition, the power components of the power converter make the compact design of the power supply difficult. To resolve these problems, this paper presents a new PWM rectifier as a one-stage power conversion scheme. It experiment, it is proved from a practical point of view that 92.1% of conversion efficiency and input current which can meet harmonics regulation of the Class A in IEC61000-3-2 are achieved.

Sato, Shinji

38

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

39

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

40

Energy Technology Data Exchange (ETDEWEB)

The paper presents a new variation of selective harmonic elimination pulse-width modulation (SHE-PWM) technique suitable for a high-power five-level converter used in constant frequency utility applications. The governing system of equations associated with the elimination of specific harmonics is defined based on an equal number of switching transitions when compared against the single-carrier sinusoidal PWM (SC-SPWM) technique. For this paper, it is assumed that the modulating signal (triangular carrier) of the equivalent SC-SPWM method has twenty per unit frequency. The switching transitions for every quarter period are therefore distributed between the converter levels according to the modulation index of SC-SPWM. It is confirmed that the proposed technique offers significantly higher converter bandwidth and higher dc bus utilization for the same switching transitions. Furthermore, the proposed SHE-PWM offers better harmonic performance compared to its SC-SPWM counterpart. Selected solutions for the switching transitions are presented and verified experimentally in order to confirm the effectiveness of the proposed technique. (author)

Dahidah, Mohamed S.A. [School of Electrical and Electronic Engineering, The University of Nottingham, Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor (Malaysia); Agelidis, Vassilios G. [School of Electrical and Information Engineering, The University of Sydney, NSW (Australia)

2008-11-15

41

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; Tang, Yuejin; Shi, Jing; Li, Zhi; Ren, Li; Cheng, Shijie

2010-02-01

42

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.

43

Analytical Modeling and Implementation of Three-Phase Four-Switch Space-Vector PWM Converter.

Czech Academy of Sciences Publication Activity Database

Prague : Institute of Thermomechanics AS CR, v. v. i., 2008, s. 49-52. ISBN 978-80-87012-13-0. [Symposium Electric Machines and Drives, Power Electronics and Drive Control. Prague (CZ), 30.09.2008-02.10.2008] R&D Projects: GA AV ?R IAA200760703 Institutional research plan: CEZ:AV0Z20570509 Keywords : four-switch PWM rectifier * space vector modulation * closed-form analytical solution Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

Paclt, Zden?k; Šimek, Petr; Škramlík, Ji?í; Valouch, Viktor; Klíma, J.

44

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

45

This paper presents a new control strategy for a three phase PWM converter, which consists of applying an adaptive nonlinear control. The input-output feedback linearization approach is based on the exact cancellation of the nonlinearity, for this reason, this technique is not efficient, because system parameters can vary. First a nonlinear system modelling is derived with state variables of the input current and the output voltage by using power balance of the input and output, the nonlinear adaptive backstepping control can compensate the nonlinearities in the nominal system and the uncertainties. Simulation results are obtained using Matlab/Simulink. These results show how the adaptive backstepping law updates the system parameters and provide an efficient control design both for tracking and regulation in order to improve the power factor.

Hadri-Hamida, A.; Allag, A.; Hammoudi, M. Y.; Mimoune, S. M.; Zerouali, S.; Ayad, M. Y.; Becherif, M.; Miliani, E.; Miraoui, A.

2009-04-01

46

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.

47

Energy Technology Data Exchange (ETDEWEB)

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 {alpha}-{beta} and rotating d-q reference frame, respectively. For both predictive current control algorithms, at the beginning of each switching period, the required rectifier average voltage vector allowing the cancellation of both tracking errors of current vector components at the end of the switching period, is computed and applied during a predefined switching period by means of SVM. The main advantages of the proposed predictive current control are that no need to use hysteresis comparators or PI controllers in current control loops, and constant switching frequency. Finally, the developed predictive current control algorithms were tested both in simulations and experimentally, and illustrative results are presented here. Results have proven excellent performance in steady and transient states, and verify the validity of the proposed predictive current control which is compared to other control strategies.

Bouafia, Abdelouahab, E-mail: bouafia_aou@yahoo.f [Laboratoire d' Electronique de Puissance et Commande Industrielle (LEPCI), Universite de Setif, Departement d' electronique, Route de Bejaia, Setif (Algeria); Gaubert, Jean-Paul, E-mail: Jean.Paul.Gaubert@univ-poitiers.f [Laboratoire d' Automatique et d' Informatique Industrielle (LAII), ESIP, Universite de Poitiers (France); Krim, Fateh, E-mail: krim_f@ieee.or [Laboratoire d' Electronique de Puissance et Commande Industrielle (LEPCI), Universite de Setif, Departement d' electronique, Route de Bejaia, Setif (Algeria)

2010-12-15

48

International Nuclear Information System (INIS)

In this paper a new control strategy for voltage-source converters (VSC) is introduced. The proposed strategy consists of a nonlinear feedback controller based on feedback linearization plus a feedforward compensation of the estimated load current. In our proposal an energy function and the direct-axis current are considered as outputs, in order to avoid the internal dynamics. In this way, a full linearization is obtained via nonlinear transformation and feedback. An estimate of the load current is feedforwarded to improve the performance of the whole system and to diminish the capacitor size. This estimation allows to obtain a more rugged and cheaper implementation. The estimate is calculated by using a nonlinear reduced-order observer. The proposal is validated through different tests. These tests include performance in presence of switching frequency, measurement filters delays, parameters uncertainties and disturbances in the input voltage.

49

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

50

Directory of Open Access Journals (Sweden)

Full Text Available Com o avanço da tecnologia dos dispositivos semicondutores de potência os inversores de frequência atuam de forma importante em toda indústria. O inversor de frequência convencional contém elementos armazenadores de energia no seu elo de corrente contínua. Estes elementos armazenadores de energia são capacitores eletrolíticos e possibilitam manter a tensão do elo de corrente contínua constante. Entretanto, quanto maior sua capacitância maior é a distorção da corrente de entrada. Com a substituição do banco de capacitores eletrolíticos por um capacitor de filme, diminui-se a distorção nas correntes de entrada, porém distorções indesejadas aparecem na tensão do elo de corrente contínua e também nas correntes de saída. Estas distorções são compostas por componentes harmônicas de baixas frequências. O conversor em matriz trifásico-trifásico por sua vez, possibilita a transferência direta de energia da entrada (rede diretamente para a saída (carga sem a necessidade de elementos armazenadores de energia como acontece no inversor de frequência. Entretando o desbalanceamento das tensões da entrada afetam diretamente a forma de onda das tensões da saída. Dessa maneira, este trabalho propõe um método de controle de corrente do conversor em matriz e do inversor de frequência sem banco de capacitores do elo de corrente contínua com objetivo de compensar o desbalanceamento das tensões de saída do conversor em matriz e compensar também as componentes harmônicas de baixa frequência que aparecem nas correntes de saída do inversor de frequência. O método proposto utiliza um controlador do tipo PI e modulação por vetores espaciais para que a frequência de acionamento das chaves dos conversores seja constante.Voltage source three-phase inverter plays an important role in modern industry. The conventional voltage source inverter has a large electrolytic capacitor as energy store element in order to keep the DC-link voltage constant. However, a large electrolytic capacitor increases the input current distortion. Replacing the large electrolytic capacitor by a small film capacitor, the input current quality is improved but the DC-link voltage and the output currents are distorted by low order harmonic components. The three phase to three phase matrix converter performs electric energy direct transfer from the input to the output with sinusoidal input current although the distortion and the unbalance of the input voltages affects directly the output of the matrix converter. This paper proposes a load current control method to the matrix converter and also to the voltage source inverter in absence of the dc-link capacitor in order to compensate the distortion caused by low order harmonics components in the output currents. The proposed load current control scheme employs just one PI controller and since that the space vector modulation is used in this control, the switching frequency of the converter is kept constant. Theorical foundation, simulations results and experimental results are presented.

M. E. Oliveira Filho

2010-10-01

51

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Com o avanço da tecnologia dos dispositivos semicondutores de potência os inversores de frequência atuam de forma importante em toda indústria. O inversor de frequência convencional contém elementos armazenadores de energia no seu elo de corrente contínua. Estes elementos armazenadores de energia sã [...] o capacitores eletrolíticos e possibilitam manter a tensão do elo de corrente contínua constante. Entretanto, quanto maior sua capacitância maior é a distorção da corrente de entrada. Com a substituição do banco de capacitores eletrolíticos por um capacitor de filme, diminui-se a distorção nas correntes de entrada, porém distorções indesejadas aparecem na tensão do elo de corrente contínua e também nas correntes de saída. Estas distorções são compostas por componentes harmônicas de baixas frequências. O conversor em matriz trifásico-trifásico por sua vez, possibilita a transferência direta de energia da entrada (rede) diretamente para a saída (carga) sem a necessidade de elementos armazenadores de energia como acontece no inversor de frequência. Entretando o desbalanceamento das tensões da entrada afetam diretamente a forma de onda das tensões da saída. Dessa maneira, este trabalho propõe um método de controle de corrente do conversor em matriz e do inversor de frequência sem banco de capacitores do elo de corrente contínua com objetivo de compensar o desbalanceamento das tensões de saída do conversor em matriz e compensar também as componentes harmônicas de baixa frequência que aparecem nas correntes de saída do inversor de frequência. O método proposto utiliza um controlador do tipo PI e modulação por vetores espaciais para que a frequência de acionamento das chaves dos conversores seja constante. Abstract in english Voltage source three-phase inverter plays an important role in modern industry. The conventional voltage source inverter has a large electrolytic capacitor as energy store element in order to keep the DC-link voltage constant. However, a large electrolytic capacitor increases the input current disto [...] rtion. Replacing the large electrolytic capacitor by a small film capacitor, the input current quality is improved but the DC-link voltage and the output currents are distorted by low order harmonic components. The three phase to three phase matrix converter performs electric energy direct transfer from the input to the output with sinusoidal input current although the distortion and the unbalance of the input voltages affects directly the output of the matrix converter. This paper proposes a load current control method to the matrix converter and also to the voltage source inverter in absence of the dc-link capacitor in order to compensate the distortion caused by low order harmonics components in the output currents. The proposed load current control scheme employs just one PI controller and since that the space vector modulation is used in this control, the switching frequency of the converter is kept constant. Theorical foundation, simulations results and experimental results are presented.

M. E., Oliveira Filho; A. J., Sguarezi Filho; J. R., Gazoli; E., Ruppert Filho.

2010-10-01

52

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

53

Energy Technology Data Exchange (ETDEWEB)

The core losses and the lower-order voltage harmonics of four different chorded motors fed from sinusoidal supply and inverter voltage supply were invigilated at no-load condition. All the four motors were tested with 4, 8 and 16 kHz switching frequencies and 30, 40, 50 and 60 Hz modulation frequencies The motor with 120 deg. coil pitch has the least core losses and the lower-order voltage harmonics under sinusoidal and pulse width modulation (PWM) voltage supplies at all switching and modulation frequencies. The drop in the core losses for this motor was 46% and 53% under sinusoidal and PWM voltage supplies, respectively. The motor with 120 deg. coil pitch is recommended to be used under sinusoidal and PWM voltage supplies.

Deshmukh, Ram; Moses, A.J. [Wolfson Centre for Magnetics, Cardiff School of Engineering, Queens Building, Newport Road, Cardiff, CF24 3AA Wales (United Kingdom); Anayi, F. [Wolfson Centre for Magnetics, Cardiff School of Engineering, Queens Building, Newport Road, Cardiff, CF24 3AA Wales (United Kingdom)], E-mail: spefja@cardiff.ac.uk

2008-10-15

54

This paper presents a novel system prototype of auxiliary resonant DC link (ARDCL) assisted three phase double converter using IGBT power modules. In the ARDCL-based double converter, large current flows through the ARDCL circuit when the ARDCL circuit operates under heavier load current ranges. In addition to this, the gate pulse control timing sequences for switching power semiconductor devices used in the ARDCL circuit become more complicate actually. The active auxiliary resonant DC link snubber circuit has advantage point of small load currents which flow through the ARDCL circuit and does not actually require the complicated timing pulse control implementation for switching power semiconductor devices. In this paper, the system configuration double converter circuit and its operation principle are described for three phase voltage source type double soft-switching converter with a single ARDCL snubber. For a 10kVA prototype double converter system, conversion efficiency can be improved in addition to noise terminal voltage is reduced up to 20dBuV in maximum in the switching frequency range of 500kHz or more in comparison with the conventional three phase hard switching double converter system.

Sato, Shinji; Nagai, Shin-Ichiro; Yamamoto, Masayoshi; Rukonuzaaman, Md.; Nakaoka, Mutsuo

55

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

56

Space Vector PWM Implementation for Z-Source Inverter

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 S...

Veera Reddy, K.; Vinod, M.; Niranjan, M.; Durga Raj, M.; A V Ravi Kanth K

2014-01-01

57

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

58

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

59

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

60

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

61

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

62

Space Vector Pulse Width Modulation Scheme for a Seven-Phase Voltage Source Inverter

This paper analyses a simple space vector PWM (SVPWM) scheme for a seven-phase voltage source inverter. At first the conventional method of producing sinusoidal output voltage by utilizing six active and a zero space vectors are used to synthesis the input reference and then new PWM scheme called time equivalent space vector PWM is presented. A comparison of the proposed scheme with the conventional scheme is presented based on various performance indices. Extensive Simulation results are...

Mohd. Arif Khan; Atif Iqbal; Sk Moin Ahmad

2011-01-01

63

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

64

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

65

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

66

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

67

Space Vector Pulse Width Modulation Scheme for a Seven-Phase Voltage Source Inverter

Directory of Open Access Journals (Sweden)

Full Text Available This paper analyses a simple space vector PWM (SVPWM scheme for a seven-phase voltage source inverter. At first the conventional method of producing sinusoidal output voltage by utilizing six active and a zero space vectors are used to synthesis the input reference and then new PWM scheme called time equivalent space vector PWM is presented. A comparison of the proposed scheme with the conventional scheme is presented based on various performance indices. Extensive Simulation results are provided to validate the findings

Mohd. Arif Khan

2011-09-01

68

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

69

A controllable DC high voltage source

International Nuclear Information System (INIS)

The paper introduces a controllable DC High voltage source. Because of adopting the oscillation circuit of signal amplitude regulated and the step of deep negative feedback, there is a good following quality between output high voltage and the control digit signal. The result of application shows that performance of DC High voltage source is steady and reliable. (authors)

70

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

71

Inverted sine carrier for fundamental fortification in PWM inverters and FPGA based implementations

This paper deals with a novel natural sampled pulse width modulation (PWM) switching strategy for voltage source inverter through carrier modification. The proposed inverted sine carrier PWM (ISCPWM) method, which uses the conventional sinusoidal reference signal and an inverted sine carrier, has a better spectral quality and a higher fundamental component compared to the conventional sinusoidal PWM (SPWM) without any pulse dropping. The ISCPWM strategy enhances the fundamental output voltage...

Jeevananthan S.; Nandhakumar R.; Dananjayan P

2007-01-01

72

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

73

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

74

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

75

Soft Commutated Three-Phase Dc-Dc Converter

High efficient DC-DC Converters find its application in electric power generation, transmission, distribution and Uninterruptable power supplies (UPS). Three phase converter system as compared with single phase converter system increases power density with reduced switching stresses, efficient usage of the transformer magnetic core and smaller filter design as the frequency of the system is higher. Inorder to make use of the above mentioned advantages a ZVS-PWM three- phase current-fed push-p...

Silpa.P.T; Rajeenamol P.T

2014-01-01

76

This paper proposes a new circuit topology of the three-phase soft switching PWM inverter and PFC converter using IGBT power modules, which has the improved active auxiliary switch and edge resonant bridge leg-commutation-link soft-switching snubber circuit with pulse current regenerative feedback loop as compared with the typical auxiliary resonant pole snubber discussed previously. This three-phase soft switching PWM double converter is more suitable and acceptable for a large capacity uninterruptible power supply, PFC converter, utility-interactive bi-directional converter and so forth. In this paper, the soft switching operation and optimum circuit design of the novel type active auxiliary edge resonant bridge leg commutation link snubber treated here are described for high power applications. Both the main active power switches and the auxiliary active power switches achieve soft switching under the principles of ZVS or ZCS in this three-phase inverter switching. This three-phase soft switching commutation scheme can effectively minimize the switching surge related electromagnetic noise and the switching power losses of the power semiconductor devices; IGBTs and modules used here. This three-phase inverter and rectifier coupled double converter system does not need any sensing circuit and its peripheral logic control circuits to detect the voltage or the current and does not require any unwanted chemical electrolytic capacitor to make the neutral point of the DC power supply voltage source. The performances of this power conditioner are proved on the basis of the experimental and simulation results. Because the power semiconductor switches (IGBT module packages) have the relation of the trade-off in the switching fall time and tail current interval characteristics as well as the conductive saturation voltage characteristics, this three-phase soft-switching PWM double converter can perform to improve actual efficiency in the output power ranges with a trench gate controlled MOS power semiconductor devices which is much more improved to the low saturation voltage. The effectiveness of this is verified from a practical point of view.

Nakamura, Mantaro; Yamazaki, Takayuki; Fujii, Yuma; Ahmed, Tarek; Nakaoka, Mutsuo

77

Voltage Source Converters with Energy Storage Capability

This project deals with voltage source converters with energy storage capability. The main objective is to study the possible benefits of energy storage to a power system with a VSC as the interface between them. First of all, a converter control system is proposed for a two level VSC. In the conventional converter control, the control system usually takes the voltage measured at the point where the converter is connected and calculates the reference voltage for the converter; with a modulati...

Xie, Hailian

2006-01-01

78

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

79

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

80

The Application of FPGA in PWM Controlled Resonant Converter for an Ozone Generator

Pulse Width Modulation (PWM) is a very common technique used in many different applications. The Conventional method its generation is the heart of the inverter system. This paper present methodology to generate Sinusoidal PWM (SPWM) signal for three-phase inverter based on EP20K200EFC484-2x Altera Field Programmable Gate Array (FPGA). Designing a PWM inverter drive using FPGA has several advantages, such as: it's quick, very modifiable, and very suitable for prototyping. In this paper...

Mochammad Facta; Tole Sutikno; Zainal Salam

2013-01-01

81

Indirect Vector Control of Three Phase Induction Motor using PSIM

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, cu...

Nagulapati Kiran

2014-01-01

82

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

83

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

84

Behavior of three-phase induction motors with variable stator coil winding pitch

A pulse-width modulation (PWM) inverter and sinusoidal output voltage supplies feeding four different chorded three-phase induction motors were tested for low-order odd voltage harmonic components and efficiency at different loads. The total harmonic distortion due to the third, fifth, and ninth harmonics was lowest in a motor with 160° coil pitch energized by both sinusoidal and PWM voltages. The efficiencies of the motor with the short-chorded winding were as much as 5% and 16% higher than that of the full-pitched motor under sinusoidal and PWM excitation, respectively, due to harmonic cancellation.

Deshmukh, R.; Moses, A. J.; Anayi, F.

2006-04-01

85

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

86

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents multicarrier PWM strategies for three phase diode clamped seven level Z-source inverter. Multilevel inverters posses the advantage of reduced harmonics,high power capability and high voltage level. Impedance network in the diode clamped multilevel inverter circuit will perform boost operation. This paper focuses on multicarriersinusoidal pulse width modulation (MCSPWM strategy for the three phase seven level Z-source diode clamped inverter. Performance parameters of three phase seven level Z-source diode clamped inverter have been analyzed. A simulation model of three phase seven level Z-source diode clamped inverter developed using MATLAB/SIMULINK and its performance has been analyzed.

V.Arun#1 , B.Shanthi

2013-06-01

87

Optimal condition of memristance enhancement circuit using external voltage source

Directory of Open Access Journals (Sweden)

Full Text Available Memristor provides nonlinear response in the current-voltage characteristic and the memristance is modulated using an external voltage source. We point out by solving nonlinear equations that an optimal condition of the external voltage source exists for maximizing the memristance in such modulation scheme. We introduce a linear function to describe the nonlinear time response and derive an important design guideline; a constant ratio of the frequency to the amplitude of the external voltage source maximizes the memristance. The analysis completely accounts for the memristance behavior.

Hiroya Tanaka

2014-05-01

88

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

89

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

90

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

91

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

92

A COMPREHENSIVE ANALYSIS OF SPACE VECTOR PWM TECHNIQUE BASED ON PLACEMENT OF ZERO-SPACE VECTOR

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, the effect of placement of zero-space vector for the implementation of space vector based Pulse Width Modulation techniques for 3-phase Voltage Source Inverter is presented. Several pulse width modulation (PWM control strategies have been proposed for 3-phase voltage source inverter (VSI in the past. It is known that space vector modulation (SVM offers a degree of freedom in its implementation with regard to the placement of the zero-space vector. Apart from constructing a consistent theoretical framework, simulation results with conventional continuous SVM and various discontinuous SVM techniques are presented and all the cases are compared in this paper.

G.SAMBASIVA RAO,

2011-04-01

93

A high-precision voltage source for EIT.

Electrical impedance tomography (EIT) utilizes electrodes placed on the surface of a body to determine the complex conductivity distribution within the body. EIT can be performed by applying currents through the electrodes and measuring the electrode voltages or by applying electrode voltages and measuring the currents. Techniques have also been developed for applying the desired currents using voltage sources. This paper describes a voltage source for use in applied-voltage EIT that includes the capability of measuring both the applied voltage and applied current. A calibration circuit and calibration algorithm are described which enables all voltage sources in an EIT system to be calibrated to a common standard. The calibration minimizes the impact of stray shunt impedance, passive component variability and active component non-ideality. Simulation data obtained using PSpice are used to demonstrate the effectiveness of the circuits and calibration algorithm. PMID:16636413

Saulnier, Gary J; Ross, Alexander S; Liu, Ning

2006-05-01

94

Soft Commutated Three-Phase Dc-Dc Converter

Directory of Open Access Journals (Sweden)

Full Text Available High efficient DC-DC Converters find its application in electric power generation, transmission, distribution and Uninterruptable power supplies (UPS. Three phase converter system as compared with single phase converter system increases power density with reduced switching stresses, efficient usage of the transformer magnetic core and smaller filter design as the frequency of the system is higher. Inorder to make use of the above mentioned advantages a ZVS-PWM three- phase current-fed push-pull dc-dc converter with active clamping was developed. This converter topology allows the reuse of the energy from the leakage inductances and reduces the electromagnetic interferences (EMI. The topology was designed and simulated using MATLAB/SIMULINK. The input supply voltage used for the converter is 120V DC.

Silpa.P.T

2014-08-01

95

Rotation magnetization reversal fluxgate excited by the voltage source

Fluxgate with rotation magnetization reversal of the isotropic disk core under the harmonic voltage source excitation has been analysed and the model of the response on the measured field components has been developed. When the excitation frequency is a half of the excitation circuit resonance frequency, the fluxgate sensitivity increases quadratically with the frequency and can exceed the sensitivity of the current driven fluxgate.

Pavlyk, L. P.; Ubizskii, S. B.

2010-01-01

96

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 ...

Abdulkareem Mokif Obais; Jagadeesh Pasupuleti

2013-01-01

97

Comparative analysis of third harmonic injection PWM and SPWM control techniques for UPS inverter

Energy Technology Data Exchange (ETDEWEB)

Pulse width modulation (PWM) techniques for uninterruptible power supply (UPS) applications were investigated. The results of analytical and simulation studies were studied in order to determine the equivalence between sinusoidal PWM and third harmonic PWM control technologies in relation to the high conversion factor (CF) and total harmonic distortion (THD) of UPS applications. The inverter simulation used a 3-phase 3-wire topology with a 3-level voltage source inverter. PI controller compensators were included in each of the voltage and current controllers. A voltage major loop controller was used to ensure sinusoidal output voltage. The capacitor voltage, inductor current, and load current were used as feedback control signals. Fourier transform equations were used to characterize harmonic components for double variable controlled waveforms. Results of the study demonstrated that THD-PWMs reduced the peak size of the envelope of each phase leg voltage and increased the modulation index without causing modulation. 9 refs., 1 tab., 12 figs.

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

2008-07-01

98

PWM Converter Power Density Barriers

Power density of power electronic converters has roughly doubled every 10 years since 1970. Behind this trajectory is the continuous advancement of power semiconductor devices, which has increased the converter switching frequencies by a factor of 10 every decade. However, today's cooling concepts and passive components are major barriers for a continuation of this trend. To identify such technological barriers, this paper investigates the volume of the cooling system and passive components as a function of the switching frequency for power electronic converters and determines the switching frequency that minimizes the total volume. A power density limit of 28kW/dm3 at 300kHz is calculated for an isolated DC-DC converter, 44kW/dm3 at 820kHz for a three-phase unity power factor PWM rectifier, and 26kW/dm3 at 21kHz for a sparse matrix converter. For single-phase AC-DC conversion a general limit of 35kW/dm3 results from the DC link capacitor. These power density limits highlight the need to broaden the scope of power electronics research to include cooling systems, high frequency electromagnetics, interconnection and packaging technology, and multi-domain modelling and simulation to ensure further advancement along the power density trajectory.

Kolar, Johann W.; Drofenik, Uwe; Biela, Juergen; Heldwein, Marcelo; Ertl, Hans; Friedli, Thomas; Round, Simon

99

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

100

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

101

Power Quality Improvement using Dual Voltage Source Converter Based DVR

In any power system, The modelling and simulation of three and seven-level Dual Voltage Source Converter based dynamic voltage restorer (DVR) aimed at correcting the supply voltage sag/swell and interruption in low voltage distribution networks. The proposed design models of DVSC based DVR are expected to be most powerful solutions to minimize supply voltage disturbances of the sensitive loads. A DVR is a VSC based power electronics device connected in series between the supply and the critic...

Suresh, A.; Govindaraj, V.

2014-01-01

102

EMI in Induction Motor Drive Fed from IGCT Voltage Source.

Czech Academy of Sciences Publication Activity Database

Cambridge, MA : Electromagnetics Academy, 2007, s. 93-97. ISBN 978-1-934142-02-8. [Progress In Electromagnetics Research Symposium 2007. Prague (CZ), 27.08.2007-30.08.2007] R&D Projects: GA ?R GA102/06/0112 Institutional research plan: CEZ:AV0Z20570509 Keywords : electromagnetic interference (EMI) * induction motor drive * IGCT voltage source inverter Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

Bartoš, Stanislav; Jehli?ka, Vladimír; Škramlík, Ji?í; Valouch, Viktor

103

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

104

New Space Vector Selection Scheme for VSI Supplied Dual Three-Phase Induction Machine

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a novel space vector selection scheme applicable for the control of dual three-phase induction motor drives supplied from a six-phase voltage source inverter (VSI. The vector selection method is based on the vector space decomposition technique (VSD. Unique vector selection pattern simplifies problems related to complicated implementation of standard VSD in commercially available digital signals processors (DSP. The proposed vector selection scheme is verified through a theoretical analysis, computer simulations and practical experimental results conducted on a dual three-phase test rig prototype with control algorithm implemented in Texas Instrument?s TMS320F2808 DSP.

MILICEVIC, D.

2013-02-01

105

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Este artículo presenta el diseño y validación de un nuevo algoritmo de modulación por ancho de pulso (PWM) híbrido que supera el desempeño armónico de varios algoritmos de modulación empleados en procesos de conversión de potencia en accionamientos eléctricos AC. A partir del análisis armónico de lo [...] s algoritmos PWM más comunes en la literatura, se establece una metodología para diseñar un esquema de modulación híbrido que ofrece un desempeño armónico superior; este desempeño es verificado teórica y experimentalmente utilizando el factor de distorsión armónica total F DIST y el índice de distorsión armónica de corriente V WTHD. Abstract in english This paper presents a novel hybrid modulation algorithm which improves the harmonic performance of eight of the most common pulse width modulation (PWM) algorithms for voltage source inverters (VSI) in the electric drive field. From harmonic analysis of these eight algorithms, a methodology was esta [...] blished for designing a hybrid modulation scheme offering superior harmonic performance. The algorithm so designed was validated theoretically by calculating the total harmonic distortion factor F DIST and experimentally by measuring the weighted total harmonic distortion factor V WTHD.

Diana Jimena, López Mesa; Guillermo Alberto, Camacho Muñoz; Jaime Oscar, Díaz Chávez; Carlos Alberto, Gaviria López; Gilberto, Bolaños Pantoja.

2009-04-01

106

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

107

Analysis and Control of Pulse-Width Modulated AC to DC Voltage Source Converters.

The pulse width modulated AC to DC voltage source converter is comprehensively analyzed in the thesis. A general mathematical model of the converter is first established, which is discontinuous, time-variant and non-linear. The following three techniques are used to obtain closed form solutions: Fourier analysis, transformation of reference frame and small signal linearization. Three models, namely, a steady-state DC model, a low frequency small signal AC model and a high frequency model, are consequently developed. Finally, three solution sets, namely, the steady-state solution, various dynamic transfer functions and the high frequency harmonic components, are obtained from the three models. Two control strategies, the Phase and Amplitude Control (PAC) and a new proposed strategy, Predicted Current Control with a Fixed Switching Frequency (PCFF), are investigated. Based on the transfer functions derived from the above mentioned analysis, regulators for a closed-loop control are designed. A prototype circuit is built to experimentally verify the theoretical predictions. The analysis and experimental results show that both strategies produce nearly sinusoidal line current with unity power factor on the utility side in both rectifying and regenerating operations and concurrently provide a regulated DC output voltage on the load side. However the proposed PCFF control has a faster and improved dynamic response over the PAC control. Moreover it is also easier to be implemented. Therefore, the PCFF control is preferable to the PAC control. As an example of application, a configuration of variable DC supply under PCFF control is proposed. The quasi-optimal dynamic response obtained shows that the PWM AC to DC converter lays the foundation for building a four-quadrant, fast-dynamic system, and the PCFF control is an effective strategy for improving dynamic performances not only as applied to the AC to DC converter, but also as applied to the DC to DC chopper or other circuits.

Wu, Rusong

108

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

109

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

110

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

111

A fixed frequency sliding mode control for voltage source inverter

Energy Technology Data Exchange (ETDEWEB)

The sliding mode control theory is applied to a sinusoidal output voltage single-phase inverter with linear and non-linear loads, for fixed switching frequency operation (PWM), and only requiring the output voltage measurement. Modulation and compensation strategies are proposed, as well the design methodology of the principal parameters of the inverter and control loop. Simulation and experimental results are shown, emphasizing the robustness of the control to uncertainty model or un-modeled dynamics. The design methodology is validated by experimental results and the performance obtained with a inverter prototype. The simulation results confirm the analysis and the proposed theoretical strategy. (author) 10 refs., 14 figs.

Batistela, Nelson Jhoe; Perin, Arnaldo Jose [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Engenharia Eletrica

1995-12-31

112

DESIGN THREE PHASE OVERCURRENT RELAYS

Directory of Open Access Journals (Sweden)

Full Text Available A new design of three phase overcurrent relay described in this paper. The performance of the new design shows the ability to obtain any shape of characteristic with high accuracy and distinguish between transient and steady state fault. This design used more precise and flexible model Sachdev linear model for get any characteristic, also fast measurement theory to measure load current for less than half cycle and good hardware system design controlled by Pentium version 4 processor.

Mohammed Y Suliman,

2013-05-01

113

The Application of FPGA in PWM Controlled Resonant Converter for an Ozone Generator

Directory of Open Access Journals (Sweden)

Full Text Available Pulse Width Modulation (PWM is a very common technique used in many different applications. The Conventional method its generation is the heart of the inverter system. This paper present methodology to generate Sinusoidal PWM (SPWM signal for three-phase inverter based on EP20K200EFC484-2x Altera Field Programmable Gate Array (FPGA. Designing a PWM inverter drive using FPGA has several advantages, such as: it's quick, very modifiable, and very suitable for prototyping. In this paper, the PWM signal is used control switching action conducted by MOSFET as part of power electronics devices in resonant power converter which has 24 volt DC input voltage. As the result, by using resonant oscillation controlled by FPGA the high sinusoidal voltage until 1.0 kV peak-to peak has been generated in the load side.

Mochammad Facta

2013-07-01

114

Directory of Open Access Journals (Sweden)

Full Text Available The aim of study of this paper is design and implementation of a simple and efficient soft switched Pulse Width Modulation (PWM for three-phase induction motor drives. Soft-switching techniques have gained popularity in recent times because they offer many advantages over hard-switched Pulse Width Modulated inverters such as higher efficiency, higher power density and better performances. The quasi-resonant DC-link is being designed, the simulation and experimental results prove that it achieves soft switching of all the main switches and resonant circuit switches at the same time it posses all the capabilities of conventional sinusoidal modulated PWM inverter. Finally, the efficiency of the Soft Switched Sinusoidal PWM (SSSPWM inverter calculated from experimental results is compared with the conventional Hard Switched Sinusoidal PWM (HSSPWM inverter, under identical load conditions. It is of great significance to improve the efficiency by reducing switching losses, high power density, high reliability and low electro management interference.

S. Senguttuvan

2014-08-01

115

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

116

An imroved design for ZVT DC-DC PWM converters with snubber assisted auxiliary switch

Directory of Open Access Journals (Sweden)

Full Text Available This paper proposes an improved design to calculate the snubber auxiliary elements of ZVT DC-DC PWM converters with snubber assisted auxiliary switch. The proposed improved design guidelines are based on the reduction of the conduction losses through the auxiliary circuit. It is accomplished by the unique location of the turn-off snubber capacitor, which is shared by both active switches. By means of this improved design guidelines the converter efficiency can be increased. An efficiency comparative analysis is carried out and the experimental results, obtained from 1 kW, 100 kHz laboratory prototypes, show a relevant improvement in converter efficiency compared to the original converter design. In addition, experimental results also confirm that with the improved design the ZVT PWM converters with snubber assisted auxiliary switch can be competitive with ZVT PWM converters with constant auxiliary voltage source (True PWM ZVS pole.Este artigo propõe uma metodologia de projeto aprimorada para determinação dos componentes auxiliares para o conversor ZVT CC-CC PWM snubber assisted auxiliary switch. O procedimento de projeto proposto é baseado na redução das perdas de condução no circuito auxiliar. Isto é somente possível devido à localização do capacitor snubber de bloqueio, o qual é compartilhado por ambas as chaves ativas. Através do procedimento de projeto proposto o rendimento do conversor pode ser aumentado. Uma análise comparativa do rendimento é apresentada e os resultados experimentais, obtidos de protótipos de laboratório de 1 kW, 100 kHz, mostram uma melhoria relevante em relação ao rendimento apresentado pelo projeto original. Além disso, os resultados experimentais também confirmam que o projeto proposto para o conversor ZVT snubber assisted auxiliary switch torna-o competitivo em relação ao conversor ZVT PWM com fonte auxiliar de tensão constante (true PWM ZVS pole.

J. Russi

2005-03-01

117

An imroved design for ZVT DC-DC PWM converters with snubber assisted auxiliary switch

Scientific Electronic Library Online (English)

Full Text Available Este artigo propõe uma metodologia de projeto aprimorada para determinação dos componentes auxiliares para o conversor ZVT CC-CC PWM snubber assisted auxiliary switch. O procedimento de projeto proposto é baseado na redução das perdas de condução no circuito auxiliar. Isto é somente possível devido [...] à localização do capacitor snubber de bloqueio, o qual é compartilhado por ambas as chaves ativas. Através do procedimento de projeto proposto o rendimento do conversor pode ser aumentado. Uma análise comparativa do rendimento é apresentada e os resultados experimentais, obtidos de protótipos de laboratório de 1 kW, 100 kHz, mostram uma melhoria relevante em relação ao rendimento apresentado pelo projeto original. Além disso, os resultados experimentais também confirmam que o projeto proposto para o conversor ZVT snubber assisted auxiliary switch torna-o competitivo em relação ao conversor ZVT PWM com fonte auxiliar de tensão constante (true PWM ZVS pole). Abstract in english This paper proposes an improved design to calculate the snubber auxiliary elements of ZVT DC-DC PWM converters with snubber assisted auxiliary switch. The proposed improved design guidelines are based on the reduction of the conduction losses through the auxiliary circuit. It is accomplished by the [...] unique location of the turn-off snubber capacitor, which is shared by both active switches. By means of this improved design guidelines the converter efficiency can be increased. An efficiency comparative analysis is carried out and the experimental results, obtained from 1 kW, 100 kHz laboratory prototypes, show a relevant improvement in converter efficiency compared to the original converter design. In addition, experimental results also confirm that with the improved design the ZVT PWM converters with snubber assisted auxiliary switch can be competitive with ZVT PWM converters with constant auxiliary voltage source (True PWM ZVS pole).

J., Russi; M. L., Martins; H. A., Gründling; H., Pinheiro; J. R., Pinheiro; H. L., Hey.

2005-03-01

118

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

119

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

120

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

121

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

122

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

123

A classification methodology for zero-voltage transition PWM converters

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este artigo propõe uma metodologia de classificação para a técnica de comutação suave conhecida como ZVT. Esta classificação é baseada nos diferentes modos de implementação da fonte auxiliar de tensão. Os méritos e limitações de cada classe são apresentados. As particularidades e características de [...] cada classe são discutidas e analisadas experimental-mente em protótipos de laboratório de 1kW/100kHz. Por meio do critério de classificação proposto, qualquer topologia ZVT pode ser classificada, mesmo aquelas inéditas na literatura. Além disso, é apresentada uma visão geral dos principais con-versores ZVT PWM propostos nas últimas décadas. Abstract in english This paper presents a classification methodology of the ZVT soft-transition technique, which is based on different ways of implementation of the auxiliary circuit voltage source. The merits and limitations of each class are presented and their key features and characteristics are discussed and exper [...] imentally analyzed on the 1kW/100kHz laboratory prototypes. By means of the proposed classification criteria, any ZVT topology can be classified, even the unpublished ones. Additionally, an overview of the main ZVT PWM converters proposed in the last decades is also presented.

M. L., Martins; J. L., Russi; H. L., Hey.

2005-03-01

124

A classification methodology for zero-voltage transition PWM converters

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a classification methodology of the ZVT soft-transition technique, which is based on different ways of implementation of the auxiliary circuit voltage source. The merits and limitations of each class are presented and their key features and characteristics are discussed and experimentally analyzed on the 1kW/100kHz laboratory prototypes. By means of the proposed classification criteria, any ZVT topology can be classified, even the unpublished ones. Additionally, an overview of the main ZVT PWM converters proposed in the last decades is also presented.Este artigo propõe uma metodologia de classificação para a técnica de comutação suave conhecida como ZVT. Esta classificação é baseada nos diferentes modos de implementação da fonte auxiliar de tensão. Os méritos e limitações de cada classe são apresentados. As particularidades e características de cada classe são discutidas e analisadas experimental-mente em protótipos de laboratório de 1kW/100kHz. Por meio do critério de classificação proposto, qualquer topologia ZVT pode ser classificada, mesmo aquelas inéditas na literatura. Além disso, é apresentada uma visão geral dos principais con-versores ZVT PWM propostos nas últimas décadas.

M. L. Martins

2005-03-01

125

RANDOM PWM ALGORITHMS FOR VSI FED INDUCTION MOTOR DRIVES WITH FIXED SWITCHING FREQUENCY

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents two random PWM algorithms for voltage source inverter fed induction motor drives with fixed switching frequency for reduced harmonic distortion and acoustical noise. Moreover, the proposed algorithms use the concept of imaginary switching times, which reduces the complexity involved in the classical space vector approach. The first algorithm is developed by randomizing the time durations of zero voltage vector times and second algorithm is developed by using the variable delay technique. To validate theeffectiveness of the proposed algorithm, numerical simulation studies have been carried out on v/f controlled induction motor drives at different modulation indices and results are presented and compared.

K. SATYANARAYANA,

2010-12-01

126

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

127

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

128

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

129

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

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a three-phase rectifier, unit power factor, non-dissipative commutation in DC-DC converter and synchronized control in frequency, working with 89% of global efficiency and low level do RFI. The proposed structure allows the operation with high switching frequency. The output voltage is controlled by PWM with a constant frequency. The operation principle, theoretical analysis from DC converter, relevant equations, current balance control technique and experimental results, are shown in this paper.

João Batista Vieira Júnior

2003-01-01

130

In this paper, a three-phase two leg neutral point clamped (NPC) converter is presented for power factor correction and dc-link voltage regulation. The adopted converter has simpler circuit configuration and less number of power switches compared to three-level PWM converter. In this circuit configuration, only eight power switches and four clamping diodes with voltage stress of half the dc bus voltage are used. A simplified space vector pulse width modulation scheme (SVPWM) is also adopted t...

Bogimi Sirisha; Satish Kumar, P.; Susheela, N.

2012-01-01

131

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

132

Scientific Electronic Library Online (English)

Full Text Available Este artigo propõe dois novos algoritmos de limitação para inversores de tensão trifásicos a quatro braços. Estes baseiam-se na limitação do vetor de comando dentro da região de operação linear do inversor. O primeiro algoritmo utiliza um elipsóide inscrito no dodecaedro definido pelas extremidades [...] dos possíveis vetores de comutação do inversor, e o segundo é baseado nos planos limites desse poliedro. Uma descrição detalhada, abordando os principais pontos requeridos para a implementação digital, da modulação space vector e dos algoritmos de limitação são apresentados. Ainda, as tensões de saída e as correntes nos indutores são dinamicamente reguladas, por meio de servo controladores MIMO em eixos síncronos dq0. Estes controladores são projetados usando a técnica do regulador linear quadrático discreto de regime permanente, o qual assegura estabilidade para o sistema em toda a faixa de operação. Além disso, para prover transições suaves entre os diferentes modos de operação do inversor, são propostos algoritmos MIMO não lineares para limitar a sobrecarga da ação integral, quando o vetor de comando for limitado, e atualizar dinamicamente as variáveis dos servo controladores. Finalmente, são apresentados resultados experimentais obtidos de um protótipo de 15 kVA, totalmente controlado por um DSP TMS320F241, para validar os algoritmos propostos e demostrar o desempenho do sistema como um todo. Abstract in english This paper proposes two novel limiting algorithms for three-phase four-leg voltage source inverters to constrain the command vector inside the dodecahedron defined by the boundaries of the inverter linear operating range. The first algorithm uses an inscribed ellipsoid on the dodecahedron, and the s [...] econd one is based on the polyhedron boundary planes. A detailed description, with the key points required for a digital implementation of space vector and limiting algorithms, is given. In addition, the output voltages and the inductors currents are dynamically regulated by means of MIMO servo controller in dq0 coordinates. These controllers are designed using optimal discrete linear quadratic regulator technique, which ensures stability for the system at all operating conditions. In order to provide smooth transitions among the different modes of operation, nonlinear MIMO anti-windup algorithms are proposed to dynamically update the controllers servo variables. Finally, experimental results on a 15 kVA PWM inverter fully controlled by a DSP controller, TMS320F241, has been used to validate the feasibility of the proposed algorithm and to demonstrate the performance of the overall system.

Robinson F. de, Camargo; Fernando, Botterón; Humberto, Pinheiro; José R., Pinheiro; Hilton, Gründling; Hélio, Hey.

2004-09-01

133

Four-switch three-phase space-vector PWM AC-DC converter.

Czech Academy of Sciences Publication Activity Database

Ro?. 95, ?. 4 (2008), s. 383-397. ISSN 0020-7217 Institutional research plan: CEZ:AV0Z20570509 Keywords : AC-DC converter * space-vector pulsewidth modulation * rectifier Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.567, year: 2008

Klíma, J.; Škramlík, Ji?í; Valouch, Viktor

2008-01-01

134

Software Phase Lock Loops Applied in Three-Phase PWM Rectifier.

Czech Academy of Sciences Publication Activity Database

Košice : Technical University of Košice, 2011, s. 227-232. ISBN 978-80-553-0734-3. [International Conference on Electrical Drives and Power Electronics - EDPE 11 /17./. Stará Lesná, The High Tatras (SK), 28.10.2011-30.10.2011] R&D Projects: GA MPO(CZ) FR-TI1/330 Institutional research plan: CEZ:AV0Z20570509 Keywords : phase lock loop * unsymmetrical voltage system * harmonics Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

Šimek, Petr; Škramlík, Ji?í; Valouch, Viktor; Bejvl, Martin

135

This paper investigates the use of fuzzy logic for fault detection and diagnosis in a pulsewidth modulation voltage source inverter (PWM-VSI) induction motor drive. The proposed fuzzy technique requires the measurement of the output inverter currents to detect intermittent loss of firing pulses in the inverter power switches. For diagnosis purposes, a localization domain made with seven patterns is built with the stator Concordia current vector. One is dedicated to the healthy domain and the ...

Zidani, Fatiha; Diallo, Demba; Benbouzid, Mohamed; Nai?t-sai?d, Rachid

2008-01-01

136

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

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 shoo...

Shajith Ali, U.; Kamaraj, V.

2011-01-01

137

Input/output harmonic free current link three-phase AC power supply

The three-phase current link AC to AC power supply, a relatively new topology for AC power supply application, has several potential advantages such as smaller number of magnetic components, lower switching frequency and more rugged operation. Despite this, it has received very little attention by the researchers, and the majority of work found in the literature is confined to the application of voltage type converters in this area. This thesis presents a comprehensive systematic approach for steady state/dynamic analysis and design of three-phase current link AC to AC power supplies. Concept of PWM methods in three-phase current type converters (CTC) is explained and the associated constraints in PWM pattern generation are addressed. Several PWM techniques are described and their performance from different aspects are compared. A steady state analysis is presented based on the Fourier representation of PWM waveforms which allows an accurate prediction of the relationships between the fundamental/harmonic components of the waveforms and other system parameters. Expressions governing various steady state characteristics of the system are derived. A dynamic model using the concept of local average of signals is established. The agreement between the dynamic behavior of switching system and derived model is illustrated. Phenomenon of multiple crossing is explained and the necessary requirement for avoiding such a phenomenon is obtained. The concept of internal model controllers is introduced and its application in the inverter control system for achieving zero steady state error is described. A detailed design procedure is presented. Root-locus method is used to design the system controllers. The applicability of different models in different design problems is discussed. All s-domain designs are verified by time-domain simulations. Experiments are conducted on a 2 KVA, 60 Hz to 50 Hz power supply. A 32 bit DSP-base high performance controller is used to implement the control system. The predicted steady state and dynamic results as well as the time-domain simulations are experimentally verified.

Karshenas, Hamid Reza

138

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

139

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

140

Scientific Electronic Library Online (English)

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 cont [...] a 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. Abstract in english 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; Fernando, Botterón; Marcelo Hey, Duarte; Jéferson, Marques; Humberto, Pinheiro.

2005-12-01

141

Scientific Electronic Library Online (English)

Full Text Available Cualquier sistema de instrumentación consiste de tres elementos: el sensor o dispositivo de entrada, el procesador de señales, y el receptor o dispositivo de salida. Diversos sistemas de control automático o con retroalimentación requieren una señal eléctrica de salida en forma de pulsos con modulac [...] ión en su ancho (PWM). Generalmente la señal analógica de salida se transforma usando un convertidor de señal PWM. En este trabajo se muestra que una señal de salida PWM, con una razón ancho-de-pulso/período (duty cycle) controlado por la intensidad de la iluminación, puede obtenerse directamente utilizando un circuito que contiene un capacitor metal (compuerta semitransparente) -óxido-semiconductor (MOS-C) conectado en serie con una fuente de DC y un generador de funciones que proporciona un voltaje periódico en forma de dientes de sierra. Internamente, la conversión de señal a PWM se logra explotando los procesos físicos fuera de equilibrio que se presentan dentro del sustrato de silicio del MOS-C. La señal cuadrada PWM, cuya amplitud está limitada a 10-20 V, se obtiene mediante la amplificación de la señal de transductor usando un amplificador estándar de transimpedancia de 60 dB. La señal de salida amplificada presenta una forma de onda PWM positiva y negativa que pueden separarse usando diodos. La razón ancho-de-pulso/período de la parte positiva es proporcional a la intensidad de la iluminación, mientras que la parte negativa es inversamente proporcional a dicha intensidad. La frecuencia de operación de este instrumento se encuentra en el rango de 1 Hz hasta algunos kilohertz. La razón ancho-de-pulso/período de la señal de salida PWM varía entre 2 y 98% cuando la potencia de la iluminación es del orden de microwatts. Este nuevo transductor o sensor podría ser útil para aplicaciones en control automático, en robótica, control de iluminación, sistemas de retroalimentación, y para la detección óptica de posición sin contacto para mediciones de centrado y anulación. Finalmente, se presenta una descripción detallada de los principios físicos y de operación de este nuevo transductor. Abstract in english This work shows that the direct PWM output electric signal, with a duty cycle controlled by light intensity, can be obtained using a circuit containing a saw-tooth voltage generator connected in series with a dc voltage source and a metal (semitransparent gate) oxide semiconductor capacitor (MOS-C). [...] The internal PWM signal conversion occurs by the use of non-equilibrium physical processes in the semiconductor substrate of the MOS-C. The 10-20 V amplitude limited square PWM output signal is obtained by the amplification of the sensor signal with a standard 60 dB transimpedance amplifier. The amplified output signal presents positive and negative PWM waveforms that can be easily separated using diodes. The duty of the positive part is proportional to the light intensity, whereas the negative part is inversely proportional to the intensity. The frequency operating range of this proposed instrument varies from 1 Hz to a few kilohertz. The duty cycle of the PWM output signal varies from 2% to 98% when the incident light intensity varies in the microwatts range. These new transducers or sensors could be useful for automatic control, robotic applications, dimmer systems, feedback electronic systems, and non-contact optical position sensing for nulling and centering measurements.

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

2013-02-01

142

Energy Technology Data Exchange (ETDEWEB)

The analysed results of both voltage regulation and current-harmonic suppression of a self- excited induction generator (SEIG), under unbalanced and/or nonlinear loading conditions using a current-controlled voltage source inverter (CC-VSI) are presented. A hybrid induction-machine model based on the three-phase a-b-c and the d-q frames of reference is employed to describe the dynamic performance of the studied system. The three-phase a-b-c induction-machine model is employed to derive dynamic equations of the SEIG under nonlinear loading conditions. The synchronously rotating reference frame based on a d-q axis model is used to decompose three-phase load currents into active and reactive power currents. The three-phase a-b-c stator voltages of the SEIG and the DC bus voltage of the inverter are simultaneously controlled by a proportional-integral (PI) voltage controller and a harmonic compensator. The simulated results show that the performance of the SEIG under unbalanced and/or nonlinear loading conditions has been effectively improved by the proposed compensating scheme. (Author)

Kuo, S. -C.; Wang, L. [Department of Electrical Engineering, National Cheng Kung University, 1 University Road, Tainan, Taiwan 70101 (China)

2001-09-01

143

FPGA Implementation of a General Space Vector Approach on a 6-Leg Voltage Source Inverter

A general algorithm of a Space Vector approach is implemented on a 6-leg VSI controlling a PM synchronous machine with three independent phases. In this last case, the necessity of controlling the zero-sequence current motivates the choice of a special family of vectors, different of this one used in Pulse Width Modulation (PWM) intersective strategy and in common Space Vector PWM (SVPWM). To preserve the parallelism of the algorithm and fulfill the execution time constraints, the implementat...

Sandulescu, Paul; Idkhajine, Lahoucine; Colas, Fre?de?ric; Kestelyn, Xavier; Semail, Eric; Bruyere, Antoine

2011-01-01

144

Inverted sine carrier for fundamental fortification in PWM inverters and FPGA based implementations

Directory of Open Access Journals (Sweden)

Full Text Available This paper deals with a novel natural sampled pulse width modulation (PWM switching strategy for voltage source inverter through carrier modification. The proposed inverted sine carrier PWM (ISCPWM method, which uses the conventional sinusoidal reference signal and an inverted sine carrier, has a better spectral quality and a higher fundamental component compared to the conventional sinusoidal PWM (SPWM without any pulse dropping. The ISCPWM strategy enhances the fundamental output voltage particularly at lower modulation index ranges while keeping the total harmonic distortion (THD lower without involving changes in device switching losses. The presented mathematical preliminaries for both SPWM and ISCPWM give a conceptual understanding and a comparison of the strategies. The detailed comparison of the harmonic content and fundamental component of the ISCPWM output for different values of modulation index with the results obtained for the SPWM is also presented. Finally, the proposed modulator has been implemented in field programmable gate array (FPGA- Xilinx Spartan 3 and tested with the proto-type inverter.

Jeevananthan S.

2007-01-01

145

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

146

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)

147

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

148

Application of Discontinuous PWM Modulation in Active Power Filters

DEFF Research Database (Denmark)

Classical discontinuous pulsewidth modulations (DPWMs) may not be efficiently applied in active power filters (APFs), because it is hard to predict the peak values of the inverter current, and consequently it is difficult to calculate the position of the clamped interval, that minimizes the switching losses in any operating point. This paper proposes a new DPWM strategy applied to shunt APFs. The proposed modulation strategy detects the current vector position relative to the inverter voltage reference and determines instantaneously the optimum clamped duration on each phase. It achieves a clamped voltage pattern, with variable lengths depending on the magnitude of the inverter current. This property adaptively reduces the current stress and minimizes the inverter switching losses, regardless of its application. The proposed modulation strategy is described, analyzed and validated on a three-phase voltage source inverter, rated at 7 kVA 400 V, controlled as an APF. Udgivelsesdato: July

Blaabjerg, Frede; Asiminoaei, Lucian

2008-01-01

149

Exposed high-voltage source effect on the potential of an ionospheric satellite

A pulsed, high-voltage source, which is able to draw a current from the surrounding plasma, is seen to induce large changes in the potential of an ionospheric satellite (the Iowa Plasma Diagnostics Package flown on Space Shuttle flight STS-51F). This, in turn, may affect the operation of other instruments that use the chassis of the satellite as a ground for electrical circuits. The magnitude of the change in satellite potential is dependent upon both the orientation of the high-voltage source, relative to the plasma flow, and the characteristics of the high-voltage source. When the satellite is grounded to the Shuttle Orbiter, this effect is sufficient to change the potential of the Orbiter by a small, but noticeable, amount.

Tribble, A. C.; D'Angelo, N.; Murphy, G. B.; Pickett, J. S.; Steinberg, J. T.

1988-01-01

150

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

151

DIGITAL CONTROL OF MULTI LEVEL CASCADE INVERTER WITH VARIABLE DC VOLTAGE SOURCES

Directory of Open Access Journals (Sweden)

Full Text Available Cascade inverters have been widely an applied for the covering of high voltage and high power systems. The input power sources for an inverters needs separate DC voltage sources, if the fluctuations occur at the input voltage, The traditional method are difficult to implement conducting angels of switches to minimize the harmonic distortion of output voltage on a single chip, A switching control algorithm is proposed and validated for multilevel inverter with fluctuating DC voltage sources. In this paper simple control algorithm will proposed for multilevel inverter with variable DC voltage sources, we considered as a DC voltage ripples 10%, 15% and 20% for 27-level & 31-level inverter and the total harmonic distortion has Analyzed, the Simulations results are presented to the superiority of the proposed system.

S.NARASIMHA

2015-01-01

152

PWM Inverter control and the application thereof within electric vehicles

An inverter (34) which provides power to an A.C. machine (28) is controlled by a circuit (36) employing PWM control strategy whereby A.C. power is supplied to the machine at a preselectable frequency and preselectable voltage. This is accomplished by the technique of waveform notching in which the shapes of the notches are varied to determine the average energy content of the overall waveform. Through this arrangement, the operational efficiency of the A.C. machine is optimized. The control circuit includes a micro-computer and memory element which receive various parametric inputs and calculate optimized machine control data signals therefrom. The control data is asynchronously loaded into the inverter through an intermediate buffer (38). In its preferred embodiment, the present invention is incorporated within an electric vehicle (10) employing a 144 VDC battery pack (32) and a three-phase induction motor (18).

Geppert, Steven (Bloomfield Hills, MI)

1982-01-01

153

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

154

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

155

Investigation of voltage source design's for Electrical Impedance Mammography (EIM) Systems.

According to Jossient, interesting characteristics of breast tissues mostly lie above 1MHz; therefore a wideband excitation source covering higher frequencies (i.e. above 1MHz) is required. The main objective of this research is to establish a feasible bandwidth envelope that can be used to design a constant EIM voltage source over a wide bandwidth with low output impedance for practical implementation. An excitation source is one of the major components in bio-impedance measurement systems. In any bio-impedance measurement system the excitation source can be achieved either by injecting current and measuring the resulting voltages, or by applying voltages and measuring the current developed. This paper describes three voltage source architectures and based on their bandwidth comparison; a differential voltage controlled voltage source (VCVS) is proposed, which can be used over a wide bandwidth (>15MHz). This paper describes the performance of the designed EIM voltage source for different load conditions and load capacitances reporting signal-to-noise ratio of approx 90dB at 10MHz frequency, signal phase and maximum of 4.75k? source output impedance at 10MHz. Optimum data obtained using Pspice® is used to demonstrate the high-bandwidth performance of the source. PMID:23366207

Qureshi, Tabassum R; Chatwin, Chris R; Zhou, Zhou; Li, Nan; Wang, W

2012-01-01

156

High-frequency, three-phase current controller implementation in an FPGA

Energy Technology Data Exchange (ETDEWEB)

Three phase rectifiers with switching frequencies of 500 kHz or more require high speed current controllers. At such high switching frequencies analog controllers as well as high speed digital signal processing (DSP) systems have limited performance. In this paper, two high speed current controller implementations using two different field-programmable gate arrays (FPGA) - one for switching frequencies up to 1 MHz and one for switching frequencies beyond 1 MHz - are presented to overcome this performance limitation. Starting with the digital system design all the blocks of the signal chain, containing analog-to-digital (A/D) interface, digital controller implementation using HW-multipliers and implementation of a novel high speed, high resolution pulse width modulation (PWM) are discussed and compared. Final measurements verify the performance of the controllers. (author)

Hartmann, M.; Round, S. D.; Kolar, J. W.

2008-07-01

157

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

158

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

159

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

160

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

161

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

162

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

163

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

164

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

165

Three Phase to Three Phase Direct Matrix Converter using SPWM Technique

The principle of three phase SPWM AC-AC matrix converter using 9 bidirectional switching devices is explained. IGBT-power diode combination is used is main power switching device. Constant voltage and frequency sinusoidal supply voltage can be converted to variable voltage and frequency voltage using this converter. The working is described based on the working three phase to single phase matrix converter. MATLAB/ Simulink software is used for the simulation. The operation is analyzed for var...

Sharon D. Ronald,; A. Sheela,; S. Josephin Mary,

2013-01-01

166

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

167

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

168

Novel voltage source converter based HVDC transmission system for offshore wind farms

Offshore wind farms have recently emerged as promising renewable energy sources. For increasing distances between offshore generation and onshore distribution grid, HVDC transmission systems based on voltage source converters can be a feasible and competitive solution. This thesis presents a comprehensive evaluation of a novel integrated wind farm topology that includes the generator drive system, the turbine interconnection and the HVDC transmission. In the proposed concept, every wind turbi...

Meier, Stephan

2005-01-01

169

Optimal Control of Input Rectifier in Voltage-Source Inverter Supplied from Unbalanced Power Grid.

Czech Academy of Sciences Publication Activity Database

Montréal : IEEE, 2006, s. 1042-1045. ISBN 1-4244-0497-5. [International Symposium on Industrial Electronics 2006. Montreal (CA), 09.07.2006-13.07.2006] R&D Projects: GA ?R(CZ) GA102/06/0215 Institutional research plan: CEZ:AV0Z20570509 Keywords : unbalanced voltage supply * voltage- source inverter * pulse width modulation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

Chomát, Miroslav; Schreier, Lud?k; Bendl, Ji?í

170

Voltage Balancing of 4-level Capacitor-Clamped Voltage Source Inverter.

Czech Academy of Sciences Publication Activity Database

Prague : Institute of Thermomechanics AS CR, v. v. i., 2008, s. 32-40. ISBN 978-80-87012-13-0. [Symposium Electric Machines and Drives, Power Electronics and Drive Control. Prague (CZ), 30.09.2008-02.10.2008] R&D Projects: GA MPO FT-TA4/077 Institutional research plan: CEZ:AV0Z20570509 Keywords : capacitor-clamped voltage source inverter * multilevel inverter * capacitor balancing Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

Kokeš, Petr; Semerád, Radko

171

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

172

Control of a PWM Rectifier with Extended Functions in a Signal Digital Processor

Directory of Open Access Journals (Sweden)

Full Text Available 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, based 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

2009-01-01

173

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

174

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.

175

Three Phase to Three Phase Direct Matrix Converter using SPWM Technique

Directory of Open Access Journals (Sweden)

Full Text Available The principle of three phase SPWM AC-AC matrix converter using 9 bidirectional switching devices is explained. IGBT-power diode combination is used is main power switching device. Constant voltage and frequency sinusoidal supply voltage can be converted to variable voltage and frequency voltage using this converter. The working is described based on the working three phase to single phase matrix converter. MATLAB/ Simulink software is used for the simulation. The operation is analyzed for various modulation indexes and input voltages. The results are compared and the optimum condition for favorable operation is obtained.

Sharon D. Ronald,

2013-05-01

176

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)

177

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

178

Although power semiconductor devices such as IGBTs and GTOs have been widely used for high power industrial applications, turn-off losses of those devices due to the current tail characteristics dominate their total switching losses. A soft switching technique is very effective in cutting down the switching losses. We have proposed an energy storage system using a current-source inverter (CSI) and a zero-current switching bi-directional DC-DC converter with a simple L-C resonant circuit in our previous works. However, based on those works, the CSI circuit is turned on and off with a hard switching technique. Improvements of efficiency and performance of CSI are indispensable to implement the proposed system. This paper proposed a soft-switching bi-directional circuit topology. The switching losses of CSI are reduced by adding a commutation circuit. In order to verify effectiveness of the proposed system, the system is analyzed in terms of the characteristics of switching losses and conversion efficiency, through a theoretical approach and computer simulations based on an instantaneous value analysis model.

Kinjyo, Tatsuto; Senjyu, Tomonobu; Urasaki, Naomitsu; Fujita, Hideki

179

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

180

Design, Control, and Modeling of a New Voltage Source Converter for HVDC System

Abstract: A New Voltage Source Converter (VSC) based on neutral clamped three-level circuit is proposed for High Voltage DC (HVDC) system. The proposed VSC is designed in a multipulse configuration. The converter is operated by Fundamental Frequency Switching (FFS). A new control method is developed for achieving all the necessary control aspects of HVDC system such as independent real and reactive power control, bidirectional real and reactive power control. The basic of the control method is varying the pulse width and by keeping the dc link voltage constant. The steady state and dynamic performances of HVDC system interconnecting two different frequencies network are demonstrated for active and reactive power control. Total number of transformers used in this system are reduced to half in comparison with the two-level VSCs for both active and reactive power control. The performance of the HVDC system is improved in terms of reduced harmonics level even at fundamental frequency switching. The harmonic performance of the designed converter is also studied for different value of the dead angle (?), and the optimized range of the dead angle is achieved for varying reactive power requirement. Simulation results are presented for the designed three level multipulse voltage source converters with the proposed control algorithm.

Mohan, Madhan; Singh, Bhim; Ketan Panigrahi, Bijaya

2013-05-01

181

This paper describes the modeling and control of a three-phase grid-connected converter fed by a photovoltaic array. The converter is composed of an isolated DC-DC converter and a three-phase DC-AC voltage source inverter The converters are modeled in order to obtain small-signal transfer functions that are used in the design of three closed-loop controllers: for the output voltage of the PV array, the DC link voltage and the output currents. Simulated and experimental results are presented.E...

Marcelo Gradella Villalva; Marcos Fernando Espindola; Thais Gama de Siqueira; Ernesto Ruppert

2011-01-01

182

The circuit presented in this paper aims at providing three 40 Vpp 50Hz AC voltages sources with 120-degree phase separation between them. This is a fully analogue circuit that uses standard, low-cost electronic components without resorting to a microcontroller as previously proposed by Shirvasar et al [1]. This circuit may serve as a basis for a low-voltage 3P-AC power supply that students may safely use to realize experiments, i.e. about the principles and applications of three-phase AC power lines, without the risk of electric shocks.

Llopis, Francisco

2013-01-01

183

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

184

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, a three-phase two leg neutral point clamped (NPC converter is presented for power factor correction and dc-link voltage regulation. The adopted converter has simpler circuit configuration and less number of power switches compared to three-level PWM converter. In this circuit configuration, only eight power switches and four clamping diodes with voltage stress of half the dc bus voltage are used. A simplified space vector pulse width modulation scheme (SVPWM is also adopted to track the line current commands. A reference voltage vector is generated on the ac terminal for drawing the sinusoidal line currents with unity power factor. This algorithm reduces the time required to calculate the switching time durations of voltage vectors. The simulation results have been presented to verify the validity and effectiveness of the proposed control strategy.

Bogimi Sirisha

2012-03-01

185

International Nuclear Information System (INIS)

This paper focuses on the detection of a rotor cage fault in a three-phase PWM feed induction motor. In inverter-fed machines there are some difficulties for the detection of a rotor cage fault. These difficulties are due to the fault signature that will be contained in the currents or voltages applied to the machine. In this way, a new approach based on the current and a virtual flux is proposed. The use of the virtual flux allows the improving of the signal to noise ratio. This approach also allows the identification of a rotor cage fault independently of the type of control used in the ac drive. The theoretical principle of this method is discussed. Simulation and experimental results are presented in order to show the effectiveness of the proposed approach

186

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

187

FPGA Techniques Based New Hybrid Modulation Strategies for Voltage Source Inverters.

This paper corroborates three different hybrid modulation strategies suitable for single-phase voltage source inverter. The proposed method is formulated using fundamental switching and carrier based pulse width modulation methods. The main tale of this proposed method is to optimize a specific performance criterion, such as minimization of the total harmonic distortion (THD), lower order harmonics, switching losses, and heat losses. The proposed method is articulated using fundamental switching and carrier based pulse width modulation methods. Thus, the harmonic pollution in the power system will be reduced and the power quality will be augmented with better harmonic profile for a target fundamental output voltage. The proposed modulation strategies are simulated in MATLAB r2010a and implemented in a Xilinx spartan 3E-500 FG 320 FPGA processor. The feasibility of these modulation strategies is authenticated through simulation and experimental results. PMID:25821852

Sudha, L U; Baskaran, J; Elankurisil, S A

2015-01-01

188

Influence of current limitation on voltage stability with Voltage Sourced Converter HVDC

DEFF Research Database (Denmark)

A first study of voltage stability with relevant amount of Voltage Sourced Converter based High Voltage Direct Current (VSC-HVDC) transmission is presented, with particular focus on the converters' behaviour when reaching their rated current. The detrimental effect of entering the current limitation on the Power-Voltage (PV) curves at a load bus is exemplified on a three-bus system, proposing a method to model the converters in current limiting mode through ideal current sources. The influence of the current magnitude and angle on the reduced stability margin is analysed and results show that, when the current limit is reached, despite the detrimental effect brought about by an increased equivalent transmission impedance, the loss of stability margin can be minimised by proper control of the converter.

Zeni, Lorenzo; Johannsson, Hjortur

2013-01-01

189

Influence of current limitation on voltage stability with voltage sourced converter HVDC

DEFF Research Database (Denmark)

A first study of voltage stability with relevant amount of Voltage Sourced Converter based High Voltage Direct Current (VSC-HVDC) transmission is presented, with particular focus on the converters’ behaviour when reaching their rated current. The detrimental effect of entering the current limitation on the Power-Voltage (PV) curves at a load bus is exemplified on a three-bus system, proposing a method to model the converters in current limiting mode through ideal current sources. The influence of the current magnitude and angle on the reduced stability margin is analysed and results show that, when the current limit is reached, despite the detrimental effect brought about by an increased equivalent transmission impedance, the loss of stability margin can be minimised by proper control of the converter.

Zeni, Lorenzo; Jóhannsson, Hjörtur

2013-01-01

190

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

191

Design of a high voltage source to fabricate fiber optic arc induced gratings

In this paper we propose a high voltage source which is controlled by a communication port I/O of a data acquisition card. The graphical programming language LabView is employed for this task. We make use of this source to produce optical fiber gratings by inducing an electric arc with the point by point procedure. It has a control section to modify the arc duration time and thus the voltage and current applied to the fiber by means of two electrodes. The experimental setup by which we characterized the gratings is depicted and we also present the transmitting spectrum. The gratings were fabricated with SMF-28 fiber but microstructured fiber can be exploited too. These gratings can be used with optical fiber lasers as optical filters and in the implementation of optical sensors.

Mata-Chavez, R. I.; Estudillo-Ayala, J. M.; Hernández-Garcia, J. C.; Rojas-Laguna, R.; Anzueto-Sanchez, G.; Martínez-Ríos, A.; Trejo-Duran, M.; Alvarado-Méndez, E. A.; Andrade-Lucio, J. A.

2007-03-01

192

The stable operating power limits of a small scale HVDC system composed of voltage source converters (VSC-HVDC system) are analyzed with a simple model. The VSC-HVDC system could operate where the AC system must be somewhat larger in capacity than the VSC-HVDC system capacity. The stable operating power limits were between one and two times the SCR (short circuit ratio). When the inverter of the VSC-HVDC system was operated with lead reactive (capacitive) power control conditions, the stable operating limits were increased through AC voltage stabilization. When the inverter was a STATCOM operation, it could operate regardless of the SCR but regions within allowable AC voltage variations.

Konishi, Hiroo; Takahashi, Choei; Kishibe, Hideto; Sato, Hiromichi

193

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

194

An Impedance-Based Stability Analysis Method for Paralleled Voltage Source Converters

DEFF Research Database (Denmark)

This paper analyses the stability of paralleled voltage source converters in AC distributed power systems. An impedance-based stability analysis method is presented based on the Nyquist criterion for multiloop system. Instead of deriving the impedance ratio as usual, the system stability is assessed based on a series of Nyquist diagrams drawn for the terminal impedance of each converter. Thus, the effect of the right half-plane zeros of terminal impedances in the derivation of impedance ratio for paralleled source-source converters is avoided. The interaction between the terminal impedance of converter and the passive network can also be predicted by the Nyquist diagrams. This method is applied to evaluate the current and voltage controller interactions of converters in both grid-connected and islanded operations. Simulations and experimental results verify the effectiveness of theoretical analysis.

Wang, Xiongfei; Blaabjerg, Frede

2014-01-01

195

A very low noise, high accuracy, programmable voltage source for low frequency noise measurements

In this paper an approach for designing a programmable, very low noise, high accuracy voltage source for biasing devices under test in low frequency noise measurements is proposed. The core of the system is a supercapacitor based two pole low pass filter used for filtering out the noise produced by a standard DA converter down to 100 mHz with an attenuation in excess of 40 dB. The high leakage current of the supercapacitors, however, introduces large DC errors that need to be compensated in order to obtain high accuracy as well as very low output noise. To this end, a proper circuit topology has been developed that allows to considerably reduce the effect of the supercapacitor leakage current on the DC response of the system while maintaining a very low level of output noise. With a proper design an output noise as low as the equivalent input voltage noise of the OP27 operational amplifier, used as the output buffer of the system, can be obtained with DC accuracies better that 0.05% up to the maximum output of 8 V. The expected performances of the proposed voltage source have been confirmed both by means of SPICE simulations and by means of measurements on actual prototypes. Turn on and stabilization times for the system are of the order of a few hundred seconds. These times are fully compatible with noise measurements down to 100 mHz, since measurement times of the order of several tens of minutes are required in any case in order to reduce the statistical error in the measured spectra down to an acceptable level.

Scandurra, Graziella; Giusi, Gino; Ciofi, Carmine

2014-04-01

196

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

197

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

198

Energy Technology Data Exchange (ETDEWEB)

The pulse width modulated (PWM) inverter power supplies have been used increasingly to drive many electromagnetic devices for various purposes. When typical magnetic cores are energized by such voltage waveforms, additional iron losses occur due to distorted flux waveform. Most of these losses are due to an increase in frequency dependent losses. It should be noted that core geometry may also affect total power loss increase under PWM voltage excitation. This is because of a different magnetization process with respect to sinusoidal excitation. The effects of geometrical factors on magnetic properties of wound toroidal cores made of 3% grain oriented electrical steel were investigated. The results indicated that geometrical factors affect an iron loss increase under PWM voltage excitation as well as under sinusoidal excitation. The aspect ratio is particularly important in this regard.

Tutkun, N. E-mail: n_tutkun@yahoo.com; Moses, A.J

2004-10-01

199

Evolutionary Computing Based Area Integration PWM Technique for Multilevel Inverters

The existing multilevel carrier-based pulse width modulation (PWM) strategies have no special provisions to offer quality output, besides lower order harmonics are introduced in the spectrum, especially at low switching frequencies. This paper proposes a novel multilevel PWM strategy to corner the advantages of low frequency switching and reduced total harmonic distortion (THD). The basic idea of the proposed area integration PWM (AIPWM) method is that the area of the required sinusoidal (fun...

Jeevananthan, S.

2007-01-01

200

Design and Implementation of Three Phase Unbalanced Voltage Motor Controller

Directory of Open Access Journals (Sweden)

Full Text Available A state-of-the-art-technology was used to design the unbalanced three phase motor controller. The fluctuation of line voltage has been questioned in recent times due to the use of heavy powered machine with three phases. This paper is focused on deriving a control scheme to drive a three phase motor that could be used in industry or households. The very simple circuitry has been employed in this design. To do this, extensive MATLAB analysis and PSpice software was conducted in order to optimize the control system and finally the results are practically verified.

M. A. A. Mashud

2013-09-01

201

Sensorless digital control of grid connected three phase converters for renewable sources

Energy Technology Data Exchange (ETDEWEB)

Power electronic converters have become popular in the field of power transformation for renewable energy. Power electronics converters achieve high efficiency, and the price of their components is falling, thus making them even more beneficial for renewable energy applications. Those systems coupled to the grid need to withstand certain utility-defined circumstances which may occur during operation. Additionally the new net regulations for large generation plants specify that during specified severe grid disturbances the relatively delicate converters should stay connected supporting the system. For PV inverters the forthcoming standards may optionally add the possibility of reactive power compensation where for wind-power those standards are already in use. This thesis focuses on reliable, sensor-less control of the PWM converters coping with varying grid conditions and existing problems. The thesis presents a variety of digital control solutions for interfacing PWM converter with the grid, synchronization, sensor less operation and grid impedance detection. The introductory chapter gives the fundamental theory about three-phase converters and control.The following chapters deal with unbalanced condition and symmetric component decomposition, which is the tool to cope with unbalanced grid voltages or currents. A sensor-less operation method using dual frame virtual flux model is presented with good results. In addition sensor-less synchronization to the grid is shown. Moreover an algorithm based on virtual flux for grid inductance estimation is also successfully demonstrated. Knowing the grid inductance is important during weak grid operation, since it is needed in order to provide unity power factor to the point of common connection. At the end of the thesis, a control algorithm for voltage harmonic compensation during stand alone operation is presented. The presented algorithm gives the possibility to supply high quality power in isolated islands, where the load is unknown. Furthermore, this algorithm can be successfully used for UPS applications. The last chapter applies the voltage harmonic control to the Z-source converter having the possibility of achieving higher ac voltage than in conventional VSI, results are promising. (Author)

Kulka, Arkadiusz

2009-03-15

202

Nonlinear control of voltage source converters in AC-DC power system.

This paper presents the design of a robust nonlinear controller for a parallel AC-DC power system using a Lyapunov function-based sliding mode control (LYPSMC) strategy. The inputs for the proposed control scheme are the DC voltage and reactive power errors at the converter station and the active and reactive power errors at the inverter station of the voltage-source converter-based high voltage direct current transmission (VSC-HVDC) link. The stability and robust tracking of the system parameters are ensured by applying the Lyapunov direct method. Also the gains of the sliding mode control (SMC) are made adaptive using the stability conditions of the Lyapunov function. The proposed control strategy offers invariant stability to a class of systems having modeling uncertainties due to parameter changes and exogenous inputs. Comprehensive computer simulations are carried out to verify the proposed control scheme under several system disturbances like changes in short-circuit ratio, converter parametric changes, and faults on the converter and inverter buses for single generating system connected to the power grid in a single machine infinite-bus AC-DC network and also for a 3-machine two-area power system. Furthermore, a second order super twisting sliding mode control scheme has been presented in this paper that provides a higher degree of nonlinearity than the LYPSMC and damps faster the converter and inverter voltage and power oscillations. PMID:24906895

Dash, P K; Nayak, N

2014-07-01

203

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

204

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

205

DEFF Research Database (Denmark)

The classical discontinuous pulsewidth modulations (DPWMs) cannot be efficiently applied in active power filters (APFs) because it is difficult to predict the peak values of the inverter current. Consequently, it is difficult to calculate the optimal position of the clamped interval to minimize the switching losses in any operating point. This paper proposes a new DPWM strategy for shunt APFs. The proposed modulation strategy detects the current vector position relative to the inverter voltage reference and determines the optimum clamped duration for each phase, in terms of switching power losses. It achieves a clamped voltage pattern, with variable lengths depending on the magnitude of the inverter current. This property reduces the current stress and minimizes the inverter switching losses. The proposed modulation strategy is described, analyzed, and validated on a three-phase voltage source inverter, rated at 3 kVA, 400 V, controlled as an APF. Udgivelsesdato: January

Blaabjerg, Frede; Asiminoaei, Lucian

2008-01-01

206

A New Generalized Discontinuous-PWM Strategy for Active Power Filters

DEFF Research Database (Denmark)

Classical discontinuous pulse width modulations (DPWM's) may not be efficiently applied in active power filters, because it is hard to predict the peak values of the inverter current, and consequently it is difficult to calculate the position of the clamped interval, that minimizes the switching losses in any operating point. This paper proposes a new discontinuous pulse width modulation strategy applied to shunt active power filters. The proposed modulation strategy detects the current vector position relative to the inverter voltage reference and determines instantaneously the optimum clamped duration on each phase. It achieves a clamped voltage pattern, with variable lengths depending on the magnitude of the inverter current. This property adaptively reduces the current stress and minimizes the inverter switching losses, regardless of its application. The proposed modulation strategy is described, analyzed and validated on a three-phase voltage source inverter, rated at 7 kVA, 400 V, controlled as an active power filter.

Asiminoaei, Lucian; Rodriguez, Pedro

2007-01-01

207

Research on coordinate transformation of the three-phase circuit

The different three-phase circuit coordinate transformation matrixes are given in relevant literatures , which may cause some difficulties to understand and apply the coordinate transformation. The paper presents a general expression of the coordinate transformation matrixes in three-phase circuit and points out that the coordinate transformation matrixes having different specific expressions are due to existing the parameters which can be selected in the general expression. On this basis, th...

Tian Ming Xing; yan hong; Yuan Dong Sheng

2013-01-01

208

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

209

Numerical Iterative Methods Solving three-phase Multilevel Voltage Converter.

Czech Academy of Sciences Publication Activity Database

Vol. IEEE CACSC CFP10CAC-CDR. Yokohama : IEEE, 2010, s. 1801-1806. ISBN 978-1-4244-5355-9. [The 10th IEEE International Symposium on Computer-Aided Control System Design. Yokohama, Kanagawa (JP), 08.09.2010-10.09.2010] R&D Projects: GA MŠk(CZ) 1M0567 Grant ostatní: GA ?R(CZ) GPP103/10/P323 Institutional research plan: CEZ:AV0Z10750506 Keywords : multilevel converter * numerical methods * optimal PWM * selective harmonic elimination Subject RIV: BC - Control Systems Theory

Kujan, Petr

210

This paper presents some implementation details of a three-phase to three-phase matrix converter prototype. The bidirectional semiconductor switches were built using discrete IGBTs and fast diodes. Design aspects such as protection against overvoltage and short-circuit, commutation process of bi-directional switches, and input filter are addressed in this paper.Este trabalho apresenta aspectos relacionados a implementação experimental de um conversor trifásico em matriz. As chaves bidireci...

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

2012-01-01

211

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

212

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

213

Three-phase flow measurement in the petroleum industry

International Nuclear Information System (INIS)

The problem of how to accurately measure the flowrate of oil–gas–water mixtures in a pipeline remains one of the key challenges in the petroleum industry. This paper discusses why three-phase flow measurement is still important and why it remains a difficult problem to solve. The measurement strategies and principal base technologies currently used by commercial manufacturers are described, and research developments that could influence future flowmeter design are considered. Finally, future issues, which will need to be addressed by manufacturers and users of three-phase flowmeters, are discussed. (topical review)

214

Class D amplifier power stage with PWM feedback loop

This paper presents a Second-Order Pulse Width Modulation (PWM) feedback loop to improve Power Supply Rejection (PSR) of any open-loop PWM Class-D amplifiers (CDAs). PSR of the audio amplifier has always been a key parameter in mobile phone applications. In contrast to Class AB amplifiers, the poor PSR performance has always been the major drawback for CDAs with half-bridge connected power stage. The proposed PWM feedback loop is fabricated using GLOBALFOUNDRIES' (GF’s) 0.18 µm CMOS p...

Lam, C. K.; Tan, M. T.; Cox, Stephen M.; Yeo, K. S.

2013-01-01

215

REDUCED-PARTS THREE-PHASE UNINTERRUPTIBLE POWER SUPPLY

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, a three-phase on-lineuninterruptible power supply with reducednumber of switches topology is presented. The newtopology has less number of power electronicdevices as well as control functions. Differentoperating modes of the system are investigated aswell. Simulation and experimental results arepresented, which show the viability of the proposedtopology.

R?ZVAN DANIEL ALBU

2008-05-01

216

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

217

Evolutionary Computing Based Area Integration PWM Technique for Multilevel Inverters

Directory of Open Access Journals (Sweden)

Full Text Available The existing multilevel carrier-based pulse width modulation (PWM strategies have no special provisions to offer quality output, besides lower order harmonics are introduced in the spectrum, especially at low switching frequencies. This paper proposes a novel multilevel PWM strategy to corner the advantages of low frequency switching and reduced total harmonic distortion (THD. The basic idea of the proposed area integration PWM (AIPWM method is that the area of the required sinusoidal (fundamental output and the total area of the output pulses are made equal. An attempt is made to incorporate two soft computing techniques namely evolutionary programming (EP and genetic algorithm (GA in the generation and placement of switching pulses. The results of a prototype seven-level cascaded inverter experimented with the novel PWM strategies are presented.

S. Jeevananthan

2007-06-01

218

PWM Control and Experiment of Modular Multilevel Converters

A modular multilevel converter (MMC) is one of the next-generation multilevel PWM converters intended for high- or medium-voltage power conversion without transformers. The MMC consists of cascade connection of multiple bidirectional PWM chopper-cells, thus requiring voltage-balancing control of their chopper-cells. However, no paper or article has been presented or published on the voltage-balancing control with theoretical and experimental verifications. This paper deals with two types of modular multilevel PWM converters with focus on their circuit configurations and voltage-balancing control. Combination of averaging and balancing controls enables the MMCs to achieve voltage balancing without any external circuit. The viability of the MMCs as well as the effectiveness of the PWM control method is confirmed by simulation and experiment.

Hagiwara, Makoto; Akagi, Hirofumi

219

Optimized Hybrid Phase Disposition PWM Control Method for Multilevel Inverter

This paper presents a new variation of hybrid phase disposition pulse width modulation technique suitable for cascaded multilevel inverter. A hybrid PDPWM is developed based on low frequency PWM and high frequency Sinusoidal PWM. An optimized sequential switching scheme introduced in this proposed method to equalize electro static and electro magnetic stress among the power devices. It is confirmed that the proposed technique offers significantly lower switching losses and switching transitio...

Govindaraju, C.; K Baskaran, Dr

2010-01-01

220

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

221

Flow coupling during three-phase gravity drainage.

We measure the three-phase oil relative permeability k(ro) by conducting unsteady-state drainage experiments in a 0.8 m water-wet sand pack. We find that when starting from capillary-trapped oil, k(ro) shows a strong dependence on both the flow of water and the water saturation and a weak dependence on oil saturation, contrary to most models. The observed flow coupling between water and oil is stronger in three-phase flow than two-phase flow, and cannot be observed in steady-state measurements. The results suggest that the oil is transported through moving gas-oil-water interfaces (form drag) or momentum transport across stationary interfaces (friction drag). We present a simple model of friction drag which compares favorably to the experimental data. PMID:21797432

Dehghanpour, H; Aminzadeh, B; Mirzaei, M; DiCarlo, D A

2011-06-01

222

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

223

Accurate parameter estimation for unbalanced three-phase system.

Smart grid is an intelligent power generation and control console in modern electricity networks, where the unbalanced three-phase power system is the commonly used model. Here, parameter estimation for this system is addressed. After converting the three-phase waveforms into a pair of orthogonal signals via the ? ?-transformation, the nonlinear least squares (NLS) estimator is developed for accurately finding the frequency, phase, and voltage parameters. The estimator is realized by the Newton-Raphson scheme, whose global convergence is studied in this paper. Computer simulations show that the mean square error performance of NLS method can attain the Cramér-Rao lower bound. Moreover, our proposal provides more accurate frequency estimation when compared with the complex least mean square (CLMS) and augmented CLMS. PMID:25162056

Chen, Yuan; So, Hing Cheung

2014-01-01

224

International Nuclear Information System (INIS)

Dielectric-barrier discharges (DBDs) in atmospheric pressure air have been studied by using a power-frequency voltage source. In this paper the electrical characteristics of DBDs using glass and alumina dielectrics have been investigated experimentally. According to the Lissajous figures of voltage-charges, it is discovered that the discharge power for an alumina dielectric is much higher than that for a glass dielectric at the same applied voltage. Also, the voltage-current curves of the glass and alumina dielectrics confirm the fact that the dielectric barriers behave like semiconducting materials at certain applied voltages. (low temperature plasma)

225

This paper develops a novel method for the detection and isolation of open-transistor faults in voltage-source inverters feeding induction motors. Based on analyzing the load currents trajectories after Concordia transformation, six diagnostic signals each of which indicates a certain switch are extracted and a fuzzy rule base is designed to perform fuzzy reasoning in order to detect and isolate 21 fault modes including single- and double-transistor faults. In addition, the fuzzy rules are rearranged and each of them is set to a reasonable value representing the fault modes. The simulation and experiment are carried out to demonstrate the effectiveness of the proposed fuzzy approach.

Zhang, Jianghan; Luo, Hui; Zhao, Jin; Wu, Feng

2015-02-01

226

Direct Torque Control of Three-Phase Flux Reversal Machine

In this paper the mathematical model of three phase Flux Reversal Machine (FRM), electrical gear ratio of the machine and the Direct torque control of FRM is discussed. The mathematical equations are similar to that of permanent magnet synchronous machine (PMSM). The machine model is also simulated using MATLAB for the case of machine working as a motor. Output speed, flux locus and inverter output voltages are acquired at the steady state conditions.

D S Phani Gopal Cheerla, L. Malleswari

2013-01-01

227

Direct Torque Control of Three-Phase Flux Reversal Machine

Directory of Open Access Journals (Sweden)

Full Text Available In this paper the mathematical model of three phase Flux Reversal Machine (FRM, electrical gear ratio of the machine and the Direct torque control of FRM is discussed. The mathematical equations are similar to that of permanent magnet synchronous machine (PMSM. The machine model is also simulated using MATLAB for the case of machine working as a motor. Output speed, flux locus and inverter output voltages are acquired at the steady state conditions.

D S PHANI GOPAL CHEERLA, L.MALLESWARI, DR. G R K MURTHY

2013-05-01

228

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 the thes...

Gajic?, Zoran

2008-01-01

229

Simple dynamic hysteresis modelling of three phase power transformer

A model has been developed by using the transformation of B in B— H curve into magnetic flux ?. A coefficient D, which is related to the hysteresis phenomenon, is derived under sinusoidal and non-sinusoidal flux waveform conditions according to the power loss. From the dynamic hysteresis expression, a three phase three-limb transformer model has been developed for the analytical solution of both fundamental ferroresonance and harmonics.

Wu, Z. Q.; Shirkoohi, G. H.; Cao, J. Z.

1996-07-01

230

Carbon in Detonation Products. A "Three-Phase" Modelisation

Condensed carbon is a common and rather abundant component in reactive mixtures formed in shock compressed energetic materials. However, there still remain some questions about its molecular forms in these mixtures. The choice of an accurate model to be used in high pressure, high temperature simulations is essential to ensure better prediction of energetic substances performances and constitutes a major difficulty. We describe the main theoretical features of a three-phase equation of state ...

Turkel, M. -l; Charlet, F.

1995-01-01

231

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

232

Energy Technology Data Exchange (ETDEWEB)

Investigations have been made on pulse width modulation (PWM) inverter technologies with regard to PWM waveform generating methods, the evaluating and analyzing method, and the current status of PWM inverters applied widely in industrial fields. This paper describes the main circuitry systems of PWM inverters including the voltage type inverter, the current type inverter, the multi-level inverter, and the multi-functional inverter. It also mentions different types of power devices, and configuration elements such as the drive circuit, the snapper circuit and circuit parts. Descriptions are then given on control systems with respect to methods for classifying and analyzing different types of PWM systems, modulation systems for multi-level inverters, the resonant type modulation system, modulation systems for multi-functional inverters, and other modulation systems. Configuration of control circuitry using CPU and the latest control devices are also described. The paper then describes the following methods: a loss calculation method, a torque ripple reducing method, a waveform improving method, reducing and evaluating methods for electromagnetic disturbances, a harmonics removing method, a noise reducing method, and a method to evaluate equivalent disturbance current. Finally, the paper introduces examples of the PWM systems applied practically in the railways and industrial fields. 218 refs., 144 figs., 20 tabs.

NONE

1997-05-30

233

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

234

This paper presents an efficient and reliable Genetic Algorithm-based solution for Specific Harmonic Elimination (SHE) switching pattern. This method eliminates considerable amount of lower order line voltage harmonics in Pulse Width Modulation (PWM) inverter. The determination of pulse pattern for the elimination of some lower order harmonics of a PWM inverter necessitates solving a system of nonlinear transcendental equations. Genetic Algorithm is used to solve nonlinear transcendental equa...

Vargese Jegathesan; Jovitha Jerome

2008-01-01

235

An effective system control method is presented for applying a three-phase current-source PWM converter with a deadbeat controller to active power filters (APFs). In the shunt-type configuration, the APF is controlled such that the current drawn by the APF from the utility is equal to the current harmonics and reactive current required for the load. To attain the time-optimal response of the APF supply current, a two-dimensional deadbeat control scheme is applied to APF current control. Further more, in order to cancel both the delay in the two-dimensional deadbeat control scheme and the delay in DSP control strategy, an adaptive Line Enhancer (ALE) is introduced in order to predict the desired value of three sampling periods ahead. ALE has another function of bringing the robustness to the deadbeat control system. Due to the ALE, settling time is made short in a transient state. On the other hand, total harmonic distortion (THD) of source currents can be reduced as much as possible compared to the case that ideal identification of controlled system could be made. The experimental results obtained from the DSP-based APF are also reported. The compensating ability of this APF is very high in accuracy and responsiveness although the modulation frequency is rather low.

Nishida, Katsumi; Konishi, Yoshihiro; Nakaoka, Mutsuo

236

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

237

Scientific Electronic Library Online (English)

Full Text Available Este trabalho apresenta aspectos relacionados a implementação experimental de um conversor trifásico em matriz. As chaves bidirecionais empregadas na construção do protótipo foram construídas com a utilização de componentes discretos como IGBT's e diodos rápidos. Aspectos relacionados a proteção con [...] tra sobre tensão e curto circuito, processo de comutação das chaves bidirecionais e filtro de entrada são apresentados neste trabalho juntamente com resultados experimentais da operação do conversor. Abstract in english This paper presents some implementation details of a three-phase to three-phase matrix converter prototype. The bidirectional semiconductor switches were built using discrete IGBTs and fast diodes. Design aspects such as protection against overvoltage and short-circuit, commutation process of bi-dir [...] ectional switches, and input filter are addressed in this paper.

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

2012-06-01

238

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents some implementation details of a three-phase to three-phase matrix converter prototype. The bidirectional semiconductor switches were built using discrete IGBTs and fast diodes. Design aspects such as protection against overvoltage and short-circuit, commutation process of bi-directional switches, and input filter are addressed in this paper.Este trabalho apresenta aspectos relacionados a implementação experimental de um conversor trifásico em matriz. As chaves bidirecionais empregadas na construção do protótipo foram construídas com a utilização de componentes discretos como IGBT's e diodos rápidos. Aspectos relacionados a proteção contra sobre tensão e curto circuito, processo de comutação das chaves bidirecionais e filtro de entrada são apresentados neste trabalho juntamente com resultados experimentais da operação do conversor.

Milton E. de Oliveira Filho

2012-06-01

239

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

240

Voltage Sag Mitigation by PWM Autotransformer Technique

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 t...

Vaghamshi, Ashok L.; Hetul P Vyas, Darshit T. Brahmbhatt

2012-01-01

241

Experimental dynamic evaluation of three-phase reactors

The hydrodynamic parameters were determined for two different three-phase systems (fluidized-bed and trickle-bed) through the experimental evaluation of the dynamic residence time distribution in the gas or liquid phase. For different fluid phase flow rates the fluidized-bed system was operated with a tracer in the gas phase and in the trickle-bed with a tracer in the liquid phase. The analysis of the processes was achieved through the application of different models representing the dynamic ...

Sales, F. G.; Maranha?o, L. C. A.; Pereira, J. A. F. R.; Abreu, C. A. M.

2005-01-01

242

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.)

243

Three-Phase Load Flow for Unbalanced Systems.

Traditionally, transmission systems are assumed to be balanced in power system analysis. A single phase positive sequence circuit is used in transmission system load flow analysis to simplify the study. However, when untransposed transmission lines are used in a power system due to economic considerations, space limitation; or when large unbalanced load is on the system; or when an unbalance contingency occurs on the system, this assumption may not hold true. The unbalance condition in some isolated systems are so precarious that disaster can result. One such incident occurred on a generator unit of the third nuclear power plant of Taipower in 1985. In that particular case, the turbine blades were broken and a spark ignited the liquid hydrogen when the blade vibration resonated with the 120.5 Hz rotor current. One cause of this rotor current generation is system unbalance. The unbalanced three-phase load flow program is needed in today's power system analysis. An advanced three-phase unbalanced transmission load flow program, capable of locating the unbalanced problem of large electric network systems, was proposed to be developed and tested in this research. Features of this program include simultaneous power flow of multiple voltage levels on an individual phase basis; PV bus generator, cogenerator, transformer simulation, and load modeling. It is found that delta-grounded wye step-up transformer reduces the convergence speed greatly. When too many delta-grounded wye step-up transformers exist in a large scale system and a quick approximate result of the unbalance conditions is needed, these step-up transformers can be substituted by grounded-wye to grounded-wye type transformers. This is tested on a Taipower system case which included 345KV, 161KV and 69KV feeders, network transformers, 34 PV bus generators and 188 three-phase buses. Impending unbalance problems in Taipower system were located. When not too many delta-grounded wye type transformers are in the system, as in another 345KV case with 9 delta-grounded wye type step-up transformers, the three-phase unbalanced transmission load flow analysis system would provide transmission system engineers with the capability to study actual system conditions that cannot be simulated by using existing analysis packages.

Chang, Yih-Ping

244

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

245

Experimental dynamic evaluation of three-phase reactors

Directory of Open Access Journals (Sweden)

Full Text Available The hydrodynamic parameters were determined for two different three-phase systems (fluidized-bed and trickle-bed through the experimental evaluation of the dynamic residence time distribution in the gas or liquid phase. For different fluid phase flow rates the fluidized-bed system was operated with a tracer in the gas phase and in the trickle-bed with a tracer in the liquid phase. The analysis of the processes was achieved through the application of different models representing the dynamic behavior of tracers present in the gas and liquid phases with a simulation of experimental operations of the three-phase reactors. The transfer functions developed for the two systems made it possible to estimate the hydrodynamic parameters providing the gas holdup (2.22 x 10-2 to 8.42 x 10-2 and the gas phase Peclet number (54.18 to 41.20 for the fluidized-bed and the liquid holdup (0.16 to 0.25, the liquid phase Peclet number (20.37 to 4.52 and wetting efficiency (0.34 to 0.56 for the trickle-bed.

F. G. Sales

2005-09-01

246

Experimental dynamic evaluation of three-phase reactors

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The hydrodynamic parameters were determined for two different three-phase systems (fluidized-bed and trickle-bed) through the experimental evaluation of the dynamic residence time distribution in the gas or liquid phase. For different fluid phase flow rates the fluidized-bed system was operated with [...] a tracer in the gas phase and in the trickle-bed with a tracer in the liquid phase. The analysis of the processes was achieved through the application of different models representing the dynamic behavior of tracers present in the gas and liquid phases with a simulation of experimental operations of the three-phase reactors. The transfer functions developed for the two systems made it possible to estimate the hydrodynamic parameters providing the gas holdup (2.22 x 10-2 to 8.42 x 10-2) and the gas phase Peclet number (54.18 to 41.20) for the fluidized-bed and the liquid holdup (0.16 to 0.25), the liquid phase Peclet number (20.37 to 4.52) and wetting efficiency (0.34 to 0.56) for the trickle-bed.

F. G., Sales; L. C. A., Maranhão; J. A. F. R., Pereira; C. A. M., Abreu.

2005-09-01

247

A fuzzy controlled three-phase centrifuge for waste separation

International Nuclear Information System (INIS)

The three-phase centrifuge technology discussed in this paper was developed by Neal Miller, president of Centech, Inc. The three-phase centrifuge is an excellent device for cleaning up oil field and refinery wastes which are typically composed of hydrocarbons, water, and solids. The technology is unique. It turns the waste into salable oil, reusable water, and landfill-able solids. No secondary waste is produced. The problem is that only the inventor can set up and run the equipment well enough to provide an optimal cleanup. Demand for this device has far exceeded a one man operation. There is now a need for several centrifuges to be operated at different locations at the same time. This has produced a demand for an intelligent control system, one that could replace a highly skilled operator, or at least supplement the skills of a less experienced operator. The control problem is ideally suited to fuzzy logic, since the centrifuge is a highly complicated machine operated entirely by the skill and experience of the operator. A fuzzy control system was designed for and used with the centrifuge

248

A Novel SVPWM Technology Used in PWM Rectifiers of WPGS

Directory of Open Access Journals (Sweden)

Full Text Available In order to achieve the transformation of electrical energy in Variable Speed Constant Frequency (VSCF Wind Power Generation System (WPGS, a novel Space Vector Pulse Width Modulation (SVPWM pulse trigger technology applied in high efficient PWM rectifier is proposed. Rectifier is an important part of WPGS and its performance affects the harmonic content and power factor of the power energy delivered to the grid. In order to improve the performance of PWM rectifier, a novel SVPWM pulse generator technology is proposed. Compared with other kinds of PWM pulse generator systems, Space Vector Pulse Width Modulation (SVPWM has many advantages such as clear physical concept, simple algorithm, suitable for digital implementation, high voltage utilization, low harmonic content, low switches losses and simple hardware circuit.

Zhang Junli

2013-04-01

249

Energy Technology Data Exchange (ETDEWEB)

In this paper the hybrid wind farm connected to a weak grid is investigated. By combining different electrical wind power plant systems a cost-efficient solution is obtained. The point of common connection voltage level can be controlled by injecting reactive power from a phase-compensating capacitor battery and a voltage source inverter (VSI). If the short-circuit impedance ratio is lower than 1, the demanded reactive power injection to keep the voltage at nominal level is unrealistic. For short-circuit impedance ratios of 2 or higher the demanded reactive power level is acceptable. When using both induction generators and thyristor inverters the reactive power injector VSI size should be about 0.2 pu. If the hybrid farm consists of THYs, IGs and VSIs and the active power is equally shared between the systems, the VSI had to be scaled up by 5% to handle both active and reactive power. 7 refs, 10 figs, 2 tabs

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

1996-12-01

250

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

251

Design of a 0.5V Op-Amp Based on CMOS Inverter Using Floating Voltage Sources

This letter presents a 0.5V low-voltage op-amp in a standard 0.18?m CMOS process for switched-capacitor circuits. Unlike other two-stage 0.5V op-amp architectures, this op-amp consists of CMOS inverters that utilize floating voltage sources and forward body bias for obtaining high-speed operation. And two improved common-mode rejection circuits are well combined to achieve low power and chip area reduction. Simulation results indicate that the op-amp has an open-loop gain of 62dB, and a high unity gain bandwidth of 56MHz. The power consumption is only 350?W.

Wang, Jun; Lee, Tuck-Yang; Kim, Dong-Gyou; Matsuoka, Toshimasa; Taniguchi, Kenji

252

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

253

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

254

ADVANCED COMPUTATIONAL MODEL FOR THREE-PHASE SLURRY REACTORS

Energy Technology Data Exchange (ETDEWEB)

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.

Goodarz Ahmadi

2000-11-01

255

ADVANCED COMPUTATIONAL MODEL FOR THREE-PHASE SLURRY REACTORS

Energy Technology Data Exchange (ETDEWEB)

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.

Goodarz Ahmadi

2001-10-01

256

Novel Three-Phase Clustering based on Support Vector Technique

Directory of Open Access Journals (Sweden)

Full Text Available As an important issue of machine learning, clustering receives much care in recent years. Among all clustering approaches, most of them conduct clustering operations on overall data. That is, they learn label information from all data. That comes across critical challenge in times of high-sized datasets. This paper proposes a novel Three-phase Labeling algorithm (TPL based on SVC to overcome this problem. TPL consists of selecting data representatives (Data representatives, clustering (Data representatives and then classifying non-Data representatives respectively. Support vector clustering process is modified to select qualified Data representatives in first phase. Spectrum technique governs the second-phase clustering task. Therein, the geometric properties of feature space, a new metric, and a tuning strategy of Kernel scale are used. In experiments on real datasets, TPL achieves clear improvement in accuracy and efficiency over its counterparts, and demonstrates highly competitive clustering performance in comparison with some state of the arts.

Ping Ling

2013-04-01

257

Dewetting of the three-phase contact line on solids.

Liquid adsorption on a substrate has great applications in inkjet printing as well as micro/nano fabrication. In this letter, we focus on obtaining a better understanding of the pinning-dewetting phenomenon through solubility measurements during droplet evaporation. The physical adsorption/penetration of liquid on the substrate material is considered to be responsible for the pinning of the three-phase contact line. Once the adsorption surrounding the contact line reaches equilibrium, dewetting occurs and the droplet shrinks. The absorption kinetics of water molecules on different substrates was monitored. An analytical technique was developed to measure the threshold adsorption density of trace solvents on these substrates including different polymers, silicon, and gold. PMID:20426433

Fang, Xiaohua; Pimentel, Miguel; Sokolov, Jonathan; Rafailovich, Miriam

2010-06-01

258

Mucormycosis and bone scintillography of three phases. Case description

International Nuclear Information System (INIS)

The purpose of presenting this work, besides the interest that shows the mucormycosis pathology not so frequent, it is to carry out a clinical correlation photographic with the imagenology, particularly with the bone scintillography. In the Nuclear Medicine Service it is carried out bone scintillography of three phases previous endovenous administration of 30 mCi (1110 MBq) of 99m Tc-MDP. The images are obtained with a gamma camera model Elscint APEX SPX, first each 2 seconds during the first minute, then early image to the 5 minutes and finally the late ones to the 3 hs. The bone scintillography in the phases 2 and 3 detects bigger radioactive density in left hemi side, with increment of the osteoblast activity mainly in the medial border and the floor of the orbit, in the malar bone and a little more tenuous in the superior maxillary. (Author)

259

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

260

Acoustic wave front conjugation in a three-phase media

Acoustic wave front reversal is studied in a sandy marine sediment that contains air bubbles in its fluid fraction. The considered phase conjugation is a four-wave nonlinear parametric sound interaction process caused by nonlinear bubble oscillations which are known to be dominant in acoustic nonlinear interactions in three-phase marine sediments. Two various mechanisms of phase conjugation are studied. One of them is based on the stimulated Raman-type sound scattering on resonance bubble oscillations. The second one is associated with sound interactions with bubble oscillations which frequencies are far from resonance bubble frequencies. Nonlinear equations to solve the wave-front conjugation problem are derived, expressions for acoustic wave amplitudes with a reversed wave front are obtained and compared for various frequencies of the excited bubble oscillations.

Pushkina, N I

2015-01-01

261

Three-phase radionuclide bone imaging in sports medicine

Energy Technology Data Exchange (ETDEWEB)

Three-phase radionuclide bone (TPB) imaging was performed on 238 patients with sports-related injuries. A wide variety of lesions was encountered, but the most frequent lesions seen were stress fractures of the lower part of the leg at the junction of the middle and distal thirds of the posterior tibial cortex (42 of 79 lesions). There were no differences in the type, location, or distribution of lesions between males and females or between competitive and noncompetitive athletes. In 110 cases, bone stress lesions were often diagnosed when radiographs were normal, whereas subacute or chronic soft-tissue abnormalities had few specific scintigraphic features. TPB imaging provides significant early diagnostic information about bone stress lesions. Normal examination results (53 cases) exclude underlying osseous pathologic conditions.

Rupani, H.D.; Holder, L.E.; Espinola, D.A.; Engin, S.I.

1985-07-01

262

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.)

263

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 inter...

Md. Aziz Ul Huq; Md Abul. Bashar; Farruk Ahmed

2013-01-01

264

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents an efficient and reliable Genetic Algorithm-based solution for Specific Harmonic Elimination (SHE switching pattern. This method eliminates considerable amount of lower order line voltage harmonics in Pulse Width Modulation (PWM inverter. The determination of pulse pattern for the elimination of some lower order harmonics of a PWM inverter necessitates solving a system of nonlinear transcendental equations. Genetic Algorithm is used to solve nonlinear transcendental equations for PWM-SHE. In this proposed method, harmonics up to 17th are eliminated using Genetic Algorithm without using Dual transformer. Simulations using Matlab 7.0 and PSIM 6.1 are carried out so as to validate the solution.

Vargese Jegathesan

2008-01-01

265

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

266

Directory of Open Access Journals (Sweden)

Full Text Available Compared with the three-phase, two-split-capacitor active power filter (3P2C-APF, the three-phase, four-leg active power filter (3P4L-APF has been widely used in three-phase, four-wire grid utility for power quality control due to its numerous advantages, such as higher current output capability, particularly in phase N, lower current and easier voltage control on the DC-side. However, designing the grid-connecting interface, which is between the voltage source converter (VSC and grid utility, is rather difficult due to the higher requirement for current ripple filtering in phase N, cross-coupling in four phases and lack of relevant design methodology and specification. In this paper, a four-branch LCL-type (4B-LCL grid-connecting interface is proposed for 3P4L-APF, which features better current ripple filtering performance without decreasing the current output capability in all phases. First, this paper describes the mathematical models of 4B-LCL in the fully-complex-vector form from the zero and non-zero sequence perspective, resulting in two independent and uniform equivalent circuits without cross coupling terms. Then, the 4B-LCL parameter design method based on the most comprehensive performance index is proposed, including three main stages as the specification: performance index requirement determination, fulfillment of that requirement, and verification. Finally, the validity and effectiveness of the proposed design are proven by the simulated and experimental results of a 3P4L-APF with 4B-LCL.

Wu Cao

2015-02-01

267

Simple PWM modulator topology with excellent dynamic behavior

DEFF Research Database (Denmark)

This paper proposes a new PWM modulator topology. The modulator is used in switch mode audio power amplifiers, but the topology can be used in a wide range of applications. Due to excellent transient behavior, the modulator is very suited for VRMs or other types of DC-DC or DC-AC applications.

Poulsen, SØren; Andersen, Michael Andreas E.

2004-01-01

268

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)

269

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

270

Control Strategy of PWM Rectifiers Connected to Unbalanced Grids.

Czech Academy of Sciences Publication Activity Database

-, ?. 11 (2013). ISSN 2172-038X. [International Conference on Renewable Energies and Power Quality (ICREPQ´13). Bilbao, 20.03.2013-22.03.2013] Institutional support: RVO:61388998 Keywords : electric power system * PWM rectifier * dc voltage ripple Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

Bejvl, Martin; Švec, J.; Tlustý, J.; Valouch, V.

271

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

272

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...

Mechouma Rabiaa; Azoui Boubekeur

2014-01-01

273

Boosted PWM open loop control of hydraulic proportional valves

International Nuclear Information System (INIS)

This paper presents an innovative open loop control technique for direct single stage hydraulic proportional valves whose response rate is significantly higher than that obtained by standard open loop control techniques, even comparable to more costly commercial closed loop systems. Different from standard open loop techniques, which provide the coil with a constant current proportional to the target position, the control strategy proposed in this paper employs the peak and hold (P and H) technique, widely used in Diesel engine modern supply systems, to boost the duty cycle value of the pulse width modulation (PWM) signal for a short time, namely during the spool displacement, while maintaining a lower duty cycle for holding the spool in the required opening position. The developed 'boosted PWM' technique only requires a low cost microcontroller, such as a peripheral interface controller (PIC) equipped with a metal oxide semiconductor (MOS) power driver. The PWM parameters are calibrated as a function of the spool displacement so as to maximize the response rate without introducing overshoots: the collected data are stored in the PIC. Different valve opening procedures with step response have been compared to demonstrate the merits of the proposed boosted PWM technique. No overshoots have been registered. Moreover, the proposed method is characterized by a significantly higher response rate with respect to a standard open loop control, which approximately has the same control, which approximately has the same cost. Similar experimental tests show that the proposed boosted PWM technique has a response rate even higher than that provided by the more costly commercial closed loop system mounted on the valve, and it produces no overshoots

274

Modelling and Simulation of SVPWM Inverter Fed Permanent Magnet Brushless DC Motor Drive

Variable speed drives with Pulse Width Modulation are increasingly applied in many new industrial applications for more efficient performance. Recently, developments in power electronics and semiconductor technology have lead to widespread use of power electronic converters in the power electronic systems. A number of Pulse width modulation (PWM) schemes are used to obtain variable voltage and frequency supply from a three-phase voltage source inverter. Among the different PWM techniques prop...

DEVISREE SASI; Jisha Kuruvilla, P.

2013-01-01

275

Energy Technology Data Exchange (ETDEWEB)

In this thesis the sensorless control of a permanent magnet synchronous motor (PMSM) is studied. The study has two main purposes. The first is to find a simple and effective method to estimate the rotor position and angular speed of the PMSM. The second is to test the applicability of a matrix converter in sensorless PMSM drives. A matrix converter (MC) enables a direct frequency conversion without DC-link with energy storage. In this thesis two matrix converter topologies, direct and indirect, are studied. The vector modulation and the current commutation strategies of a matrix converter are described. Non-ideal properties of frequency converters such as dead times, overlapping times and voltage losses over semiconductors are disturbances for a control system and position estimator. These non-idealities are studied and the properties of a conventional voltage source inverter are compared to direct and indirect MC topologies. The rotor position and angular speed of the PMSM can be estimated by various methods. Estimators can be divided into model based estimators and signal injection estimators. Model based estimators calculate mechanical quantities using the mathematical representation of the motor. Injection methods usually exploit the saliency of the PMSM. Injected voltage creates currents which are modulated by the rotor position. The position information can be extracted from measured currents. In this thesis the best features of model based and injection estimators are combined. In the proposed hybrid method signal injection is used at low speeds and the transition to model based estimator is performed when the speed increases. The estimator methods used in the hybrid estimator are selected by a comparative analysis and simulations. The most important criteria in the selection of the estimator method in this thesis are: simple algorithm and no need for modification of the modulator software or frequency converter. The suitability of the proposed hybrid estimator is tested by simulations and experimental tests in various operating conditions. To test the performance of the matrix converter the experiments are carried out using both MC topologies and a conventional voltage source converter. The results obtained show that a matrix converter can be used in PMSM drives where the speed and position of the PMSM are not measured. The proposed estimator method is stable over the nominal speed range including the zero speed region with full load torque. (orig.)

Eskola, M.

2006-07-01

276

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

277

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.

1991-07-01

278

Mathematical modeling of a three-phase trickle bed reactor

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The transient behavior in a three-phase trickle bed reactor system (N2/H2O-KCl/activated carbon, 298 K, 1.01 bar) was evaluated using a dynamic tracer method. The system operated with liquid and gas phases flowing downward with constant gas flow Q G = 2.50 x 10-6 m³ s-1 and the liquid phase flow (Q [...] L) varying in the range from 4.25x10-6 m³ s-1 to 0.50x10-6 m³ s-1. The evolution of the KCl concentration in the aqueous liquid phase was measured at the outlet of the reactor in response to the concentration increase at reactor inlet. A mathematical model was formulated and the solutions of the equations fitted to the measured tracer concentrations. The order of magnitude of the axial dispersion, liquid-solid mass transfer and partial wetting efficiency coefficients were estimated based on a numerical optimization procedure where the initial values of these coefficients, obtained by empirical correlations, were modified by comparing experimental and calculated tracer concentrations. The final optimized values of the coefficients were calculated by the minimization of a quadratic objective function. Three correlations were proposed to estimate the parameters values under the conditions employed. By comparing experimental and predicted tracer concentration step evolutions under different operating conditions the model was validated.

J. D., Silva; C. A. M., Abreu.

2012-09-01

279

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

280

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

281

A microfabricated device and method for proportioning and mixing electrokinetically manipulated biological or chemical materials is disclosed. The microfabricated device mixes a plurality of materials in volumetric proportions controlled by the electrical resistances of tributary reagent channels through which the materials are transported. The microchip includes two or more tributary reagent channels combining at one or more junctions to form one or more mixing channels. By varying the geometries of the channels (length, cross section, etc.), a plurality of reagent materials can be mixed at a junction such that the proportions of the reagent materials in the mixing channel depend on a ratio of the channel geometries and material properties. Such an approach facilitates voltage division on the microchip without relying on external wiring schemes and voltage division techniques external to the microchip. Microchannel designs that provide the necessary voltage division to accomplish electrokinetic valving operations using a single voltage source and a switch are also described. In addition, microchannel designs that accomplish fluidic operation utilizing a minimal number of fluidic reservoirs are disclosed.

Jacobson, Stephen C. (Knoxville, TN); Ramsey, J. Michael (Knoxville, TN)

2000-01-01

282

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

283

Three Phase Upward Flow in a Vertical Pipe

International Nuclear Information System (INIS)

Many specialized technologies need to be developed to deal with the mobilization, retrieval, transport and reliable delivery of large amounts of toxic and radioactive waste to pretreatment facilities. At these facilities the waste is prepared for long term, unsupervised storage. At Hanford as well as other DOE nuclear sites, there are many underground storage tanks that are holding many millions of gallons of toxic and radioactive waste. A class of these storage tanks can utilize pneumatic conveying for the retrieval of scarified solids that are occasionally laced with sticky sludge, followed by slurry transport to pretreatment facilities. The formation of a thin liquid film that travels upwards along the internal wall of a vertical retrieval pipe may prevent those particles that are laced with the sticky sludge from adhering to it and eventually causing instability and blockage. In this paper we develop an approach to the design of a three-phase gas-solid-liquid flow system that could transport scarified solid particles, including sticky particles, pneumatically through a vertical pipe. A liquid film is introduced and maintained along the pipe's inner wall to act as a lubricant that ensure that sticky particles will continue to be transported without permanently adhering to the pipe wall. The system's operating conditions are within the boundaries of the annular dispersed region on a typical flow pattern map of vertical flow of a gas-liquid mixture. High gas superficof a gas-liquid mixture. High gas superficial velocities combined with low liquid superficial velocities, conditions that satisfy the requirement and geometry of our proposed system, characterize such a region

284

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

285

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

286

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

287

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

288

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

289

Investigation of PWM-controlled MOSFET with inductive load

This report is the basis for a Bachelor of Science thesis in engineering done at Volvo Powertrain in Gothenburg. The problem consisted of investigating a circuit with a PWM-controlled MOSFET driving a DC-motor. The problem was to investigate what caused the circuit to break the transistor. Finally an improvement of the circuit is designed making the MOSFET withstand the stressful conditions exposed to. An overall description of the problems with switching an inductive load using a MOSFET as...

Ljunggren, Tobias

2002-01-01

290

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

291

Current Constraints of PWM Rectifier under Unbalanced Voltage Supply.

Czech Academy of Sciences Publication Activity Database

Palm Springs, California : IEEE, 2010, s. 895-900. ISBN 978-1-4244-4783-1. ISSN 1048-2334. [Annual IEEE Applied Power Electronics Conference and Exposition - APEC 2010 /25./. Palm Springs, California (US), 21.02.2010-25.02.2010] R&D Projects: GA ?R GA102/09/1273 Institutional research plan: CEZ:AV0Z20570509 Keywords : PWM rectifiers * electric drives * DC-link voltage Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering www. apec -conf.org

Chomát, Miroslav; Schreier, Lud?k; Bendl, Ji?í

292

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

293

Dynamics of IGBT based PWM Converter A Case Study

Directory of Open Access Journals (Sweden)

Full Text Available Optimizing the efficiency and dynamics of power converters is a critical tradeoff in power electronics. The increase of switching frequency can improve the dynamics of power converters, but theefficiency may be degraded as well as the switching losses. As power semiconductor devices like diodes, MOSFETS, IGBTs, Thyristors, BJTs have their own characterstics and dynamic responses. It is desired toanalyze and observe the dynamics of different semiconductor devices before they actually employed in the model. Inclusion of different PWM techniques help in the removal of power line interferences like harmonic losses, unwanted ripples, chopped frequencies, spikes. In this paper, we have studied and analyzed the dynamics of IGBT based PWM converter with subjected to different conditions like transient state, steady state feeding the RLC load. Snubber circuits are used to reduce the switching losses. The IGBT based PWM converter reflects the better dynamics with improved efficiency and reduced harmonics as compared to some other power semiconductor devices when FFT is performed and subjected to standard parameterized RLC load understeady state and transient analysis.

Vijay Shukla

2012-04-01

294

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

295

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

296

Transient performance and phase sequence of the ferroresonant type dc to three-phase ac converter

The paper introduces the transient performance of a ferroresonant type dc to three-phase ac converter. The phase converter is a hybrid type of system which consists of a single-phase SCR inverter and a ferroresonant single- to three-phase converter. The phase converter has a number of equilibrium states so that the performance depends upon the non-linearity of a ferroresonance. In order to achieve stable three-phase output voltages, the transient states have been calculated and the initial conditions leading to the three-phase oscillation have been investigated.

Yamada, S.; Tamai, S.; Bessho, K.; Nafalski, A.

1984-02-01

297

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

298

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

299

Directory of Open Access Journals (Sweden)

Full Text Available Abstract: Problem statement: Static Synchronous Compensator (STATCOM and Static Synchronous Series Compensator (SSSC have been individually applied to improve stability of power system. Approach: This study presents the coordination of a STATCOM and SSSC for improving power system stability. The swing curves of the three phase faulted power system with various cases are tested and compared. Results: The swing curve of system without FACTS devices has undamped oscillation. The system with a STATCOM or a SSSC can increase damping of power system whereas the system with coordination of a STATCOM and a SSSC provides the best results of stability improvement Conclusion: From the simulation results, the stability of power system can be much better improved by coordination control of a STATCOM and a SSSC.

Prechanon Kumkratug

2011-01-01

300

Implementation and Analytical Model of Three-Phase Four-Switch Power Factor Corrector.

Czech Academy of Sciences Publication Activity Database

Sevilla : EA4EPQ, 2007, s. 1-4. ISBN 978-84-611-4707-6. [International Conference on Renewable Energies and Power Quality - ICREPQ 07. Sevilla (ES), 28.03.2007-30.03.2007] R&D Projects: GA AV ?R IAA200760703 Institutional research plan: CEZ:AV0Z20570509 Keywords : SV PWM * four-switch converter * AD-DC power converter s Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

Klíma, J.; Škramlík, Ji?í; Valouch, Viktor

301

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

302

Three-Phase and Six-Phase AC at the Lab Bench

Utility companies generate three-phase electric power, which consists of three sinusoidal voltages with phase angles of 0 degrees, 120 degrees, and 240 degrees. The ac generators described in most introductory textbooks are single-phase generators, so physics students are not likely to learn about three-phase power. I have developed a simple way…

Caplan, George M.

2009-01-01

303

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

304

A REVIEW ON OPTIMIZATION OF ENERGY BY USING PWM INVERTER

Directory of Open Access Journals (Sweden)

Full Text Available An important part of uninterruptable powersupply is the DC to AC inverter which converts the DCvoltage from a battery to an AC voltage that is required tooperate electronic circuits. These inverters are bulky innature & consume most of the power. Therefore poweravailable at the output of inverter is less. So it is the goal ofthis paper to develop a DC/AC inverter capable ofproducing a pure sine wave which will consume less power.In this paper, we detail how the inverter’s controls wereimplemented with a digital approach using amicrocontroller for the control system and how effective andenergy efficient a PWM (Pulse Width Modulation invertercan be.

Mr. Ravindra Patil. ,Prof. M.H. Nerkar,Mr. Prashant Chaudhari

2013-01-01

305

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

306

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

307

Three-phase equilibria have been studied for the ternary system polystyrene (Mw=1.73×104)+polystyrene (Mw=7.19×105)+methylcyclohexane by numerical analyses of Gibbs free energy and experimental measurements. The calculation showed that the three-phase equilibrium appears at the temperature range from 21.4 to 23.4 °C. At these two temperatures two phases of the three coexisting phases coalesce into one phase and phase equilibria are represented by a tie line with one end being a critical point. The intersection of the two tie lines gives compositions the solution of which can give rise to the entire three-phase coexistence curve. The coexistence curve measurements were made for two solutions with different compositions near the calculated intersection. By a refractive index method coexistence curves were obtained in a temperature-total polymer composition diagram. The three-phase region was observed in a very narrow temperature range from 24.1 to 24.7 °C. The two solutions could give rise to almost entire three-phase coexistence curve and two critical points were predicted to be just above and below the three-phase region from strong opalescence. The mechanism of the three-phase separation was explained as due to the heterogeneous double plait point.

Dobashi, Toshiaki; Nakata, Mitsuo

1986-05-01

308

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

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 ...

Antal, Robert; Muntean, Nicolae; Boldea, Ion; Blaabjerg, Frede

2011-01-01

309

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

310

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

311

An Improved Switching Period Optimization Space Vector PWM Strategy

Directory of Open Access Journals (Sweden)

Full Text Available In order to improve the performance of space vector PWM (pulse width modulation, the optimization is widely used. The switching period optimization space vector PWM can reduce both total harmonic distortion and spectrum peaks, so it has important application prospects and has been widely discussed among several types of optimization strategies. Aiming at the characteristic of uncontrollable switching frequency, the study proposes an improved optimization method that can be used in both steady and non-steady states. The method uses a time window with adaptive width to control the average switching period and divides the value range of reference voltage vectors into two kinds of regions: R and Q based on period coefficients. Switching periods are dependent in the same time window, while independent in different windows. The total extra time between specified periods and optimal periods in region R can be made full use of in region Q. A simulation platform was built in software MATLAB/Simulink. The simulation result verifies excellent performance on harmonic distortion and amplitude peak reduction. The improved strategy has widespread applications in electric vehicles, industry automation and drives, household appliances and so on.

Guoqiang Chen

2014-01-01

312

Directory of Open Access Journals (Sweden)

Full Text Available The motivation of the presented research is based on the needs for development of new methods and tools for adequate simulation of Flexible Alternating Current Transmission System (FACTS devices and High Voltage Direct Current Transmission (HVDC system as part of real electric power systems (EPS. For that, a hybrid approach for advanced simulation of the FACTS and HVDC based on Voltage Source is proposed. The presented simulation results of the developed hybrid model of VSC confirm the achievement of the desired properties of the model and the effectiveness of the proposed solutions.

Ufa Ruslan A.

2014-01-01

313

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este artigo descreve a modelagem e o controle de um conversor trifásico conectado à rede alimentado por um conjunto fotovoltaico. O conversor é composto de um estágio CC-CC isolado um estágio CC-CA. São obtidas funções de transferência com as quais são projetados três sistemas de controle em malha f [...] echada: um para a tensão de entrada do arranjo de painéis solares, um para a tensão do do barramento de tensão contínua e outro para as correntes trifásicas de saída. Abstract in english This paper describes the modeling and control of a three-phase grid-connected converter fed by a photovoltaic array. The converter is composed of an isolated DC-DC converter and a three-phase DC-AC voltage source inverter The converters are modeled in order to obtain small-signal transfer functions [...] that are used in the design of three closed-loop controllers: for the output voltage of the PV array, the DC link voltage and the output currents. Simulated and experimental results are presented.

Marcelo Gradella, Villalva; Marcos Fernando, Espindola; Thais Gama de, Siqueira; Ernesto, Ruppert.

2011-06-01

314

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes the modeling and control of a three-phase grid-connected converter fed by a photovoltaic array. The converter is composed of an isolated DC-DC converter and a three-phase DC-AC voltage source inverter The converters are modeled in order to obtain small-signal transfer functions that are used in the design of three closed-loop controllers: for the output voltage of the PV array, the DC link voltage and the output currents. Simulated and experimental results are presented.Este artigo descreve a modelagem e o controle de um conversor trifásico conectado à rede alimentado por um conjunto fotovoltaico. O conversor é composto de um estágio CC-CC isolado um estágio CC-CA. São obtidas funções de transferência com as quais são projetados três sistemas de controle em malha fechada: um para a tensão de entrada do arranjo de painéis solares, um para a tensão do do barramento de tensão contínua e outro para as correntes trifásicas de saída.

Marcelo Gradella Villalva

2011-06-01

315

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

316

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

317

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

318

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

319

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

320

Control of a Three Phase Induction Motor using Single Phase Supply

Directory of Open Access Journals (Sweden)

Full Text Available In Industrial applications, two forms of electrical energy are used: Direct Current (DC and Alternating Current (AC. Usually constant voltage, constant frequency Single-Phase or Three-Phase AC is readily available. However, for different applications different forms, magnitudes and/or frequencies are required. This paper proposes how the Three-Phase inductive load is run by a Single-Phase supply by using Cycloconverter and a Scott-T connected Transformer. The controlling of a ThreePhase Induction Motor is done by Frequency variable method. Single-Phase to Three-Phase for motors offered by using high in performance, low on maintenance and is used to reduce of breakdown of electrical equipment, our range is also suitable for saving energy and require low maintenance.

G. R. Sreehitha, A. Krishna Teja, Kondenti. P. Prasad Rao

2012-06-01

321

An Improved Model Describing Mass Transfer In Three-Phase Fluidized Beds

A model for describing mass transfer in three-phase fluidized beds has been developed and tested using experimental data. The presence of two distinguishable mass transfer zones in three-phase fluidized beds led to the idea of interfacing a plug flow model (PFM) with an axial dispersion model (ADM) at the separation boundary between these zones to yield the proposed model. The model reported here has been valildated at a wide range of operating conditions and proved to perform better th...

Asfour, Abdel Fattah A.

1990-01-01

322

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

323

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

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...

Shakuntla Boora, S. K. Agarwal

2013-01-01

324

A testbed for wireless vehicle communication based on a microscopic model in the framework of three-phase traffic theory is presented. In this testbed, vehicle motion in traffic flow and analyses of a vehicle communication channel access based on IEEE 802.11e mechanisms, radio propagation modeling, message reception characteristics as well as all other effects associated with ad-hoc networks are integrated into a three-phase traffic flow model. Based on simulations of this t...

Kerner, B. S.; Klenov, S. L.; Brakemeier, A.

2007-01-01

325

The aim of the study is to develop a simple and direct approach for unbalanced radial distribution system three-phase load flow solution .The special topological characteristics of unbalanced radial distribution networks have been fully utilized to make the direct three phase load flow solution possible. Two developed matrices-the node-injection to line section-current matrix and the line section-current to node-voltage matrix - and a simple matrix multiplication are used to obtain the three ...

Subrahmanyam, J. B. V.; Pandukumar, C. Radhakrishna K.

2010-01-01

326

A new PWM based control method for forced commutated cycloconverters

International Nuclear Information System (INIS)

Highlights: ? A new control method is proposed for three-phase to single-phase cycloconverters from balanced and unbalanced input voltages. ? The proposed method has no limitation on frequency conversion and is independent of the load. ? In proposed method, the low order harmonics are not generated in the input and output quantities. ? The proposed method can be easily extended to three-phase to n-phase cycloconverters. ? We demonstrate real experimental results of the power converter. - Abstract: In this paper, a new control method is proposed for three-phase to single-phase cycloconverters for synthesizing the desired output voltage from balanced and unbalanced input voltages. The theoretical analysis of the proposed control method is given for both of the conventional topologies of three-phase to single-phase cycloconverters. Using the proposed control method, the maximum output/input voltage transfer ratios are 0.5 and 1.5 for conventional cycloconverters that consist of three and six bidirectional switches, respectively. The proposed control method has no limitation on frequency conversion and is independent of the load. In other words, using the proposed control method, the three-phase to single-phase cycloconverter can operate as a generalized transformer. Using the proposed control method, the low order harmonics are not generated in the input and output quantities. As a result, the size of the required filters is decreased. The proposed control metheased. The proposed control method can be easily extended to three-phase to n-phase cycloconverters based on the same principle of the operation. The simulation and experimental results verify the operation and performance of the proposed control method.

327

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

328

PWM Switching Frequency Effects on Eddy Current Sensors for Magnetically Suspended Flywheel Systems

A flywheel magnetic bearing (MB) pulse width modulated power amplifier (PWM) configuration is selected to minimize noise generated by the PWMs in the flywheel position sensor system. Two types of noise are addressed: beat frequency noise caused by variations in PWM switching frequencies, and demodulation noise caused by demodulation of high order harmonics of the switching voltage into the MB control band. Beat frequency noise is eliminated by synchronizing the PWM switch frequencies, and demodulation noise is minimized by selection of a switching frequency which does not have harmonics at the carrier frequency of the sensor. The recommended MB PWM system has five synchronized PWMs switching at a non-integer harmonic of the sensor carrier.

Jansen, Ralph; Lebron, Ramon; Dever, Timothy P.; Birchenough, Arthur G.

2003-01-01

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

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

331

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

332

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

333

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)

334

A dual two-level inverter fed induction motor with open-end windings is capable of generating a three-level output voltage. Several, sine-triangle and space vector pulse width modulation (PWM) switching strategies are presented for the dual-inverter scheme either using space-vector or carrier-based implementation. In this paper, a hybrid PWM switching strategy for the dual-inverter scheme is proposed employing sine-triangle PWM (SPWM) and space vector PWM (SVPWM) for the individual inverters. SPWM is theoretically analyzed and space vector based implementation of SPWM is presented using a simple offset-time concept. This is exploited to implement the hybrid PWM switching strategy for the dual two-level inverter. The implementation of the hybrid PWM switching strategy proposed in this paper do not require any look-up tables, the switching is totally automatic obviating the time-consuming task of sector identification. The implementation of the hybrid PWM scheme requires only the three instantaneous phase reference voltages corresponding to the reference space vector. The third harmonic component in the voltage appearing across the motor phase windings in the induction motor is significantly reduced (by 50%) with the use of the proposed hybrid PWM scheme as compared to the use of the PWM scheme presented earlier. Also, the percentage weighted total harmonic distortion (%WTHD) of the output voltage is significantly reduced in the entire range of speed of the induction motor driven by the dual-inverter scheme.

Srinivas, S.; Ramachandrasekhar, K.

2010-06-01

335

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

336

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

Directory of Open Access Journals (Sweden)

Full Text Available A novel three-phase phase-locked loop solution is proposed based on D-Q transformation aiming at the AC-DC rectifier with high efficiency and high power factor. The phase-locked loop is implemented digitally using the Xilinx blockset integrated with Matlab/Simulink. The three-phase digital phase-locked loop (TDPLL is elaborately designed with the parameters defined in detail. The AC-DC converter (rectifier model with the TDPLL is built and simulated in the high-speed VHS-ADC simulation platform from Canada. The simulation and test results show the TDPLL is locked right after the different three-phase voltage disturbances and very suitable for control of the rectifier with high parallelism through space vector pulse width modulation (SVPWM.

Xuegui Zhu

2013-07-01

337

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

338

Fast asymmetrical three-phase load flow based on symmetrical component

International Nuclear Information System (INIS)

This paper deals with the three-phase asymmetrical load-flow problem. It presents a solution of this problem in the sequence domain, which is more efficient than standard solutions in both the phase and the sequence domain. It specially copes with asymmetrical states of unbalanced power systems. The efficiency is achieved by introducing the following basic advancements of the standard asymmetrical load-flow calculations: 1 - Elimination of phase-shifts from the sequence circuits of three-phase transformers; 2 - Enhancement of the standard classification of power systems buses to provide a correct treatment of Q limits enforcement; 3 - Synthesizing of buses of the generators and step-up transformers in the transformers high voltage buses; thus, reducing the form of the three-phase asymmetrical load-flow models to the form of symmetrical models. The efficiency of the presented solution in memory, CPU time and robustness is confirmed on the basis of several examples. (Original)

339

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

340

This paper presents results from the implementation and testing of a PC based monitoring and fault identification scheme for a three-phase induction motor using artificial neural networks (ANNs). To accomplish the task, a hardware system is designed and built to acquire three-phase voltages and currents from a 1/3 HP squirrel-cage, three-phase induction motor. A software program is written to read the voltages and currents, which are first used to train a feed-forward neural network structure using the JavaNNS program. The trained network is placed in a LabVIEW based program formula node that monitors the voltages and currents online and displays the fault conditions and turns the motor off. The complete system is successfully tested in real time by creating different faults on the motor. PMID:17336306

Kolla, Sri R; Altman, Shawn D

2007-04-01

341

Note: A simple correlation to locate the three phase coexistence line in methane-hydrate simulations

In this Note, the three phases coexistence (hydrate-water-methane) temperature is determined by using direct coexistence simulations for a force field in which methane is described by a single Lennard-Jones site, and water is described by either SPC or SPC/E models. Results were obtained for two pressures: 100 and 400 bars. The results of this note along with those obtained in our previous work [M. M. Conde and C. Vega, J. Chem. Phys. 133, 064507 (2010)], 10.1063/1.3466751 allow to present the three phases coexistence line for a number of water models: SPC, SPC/E, TIP4P, TIP4P/2005, and TIP4P/Ice. A correlation between the three phases coexistence temperature T3 of the methane hydrate and the melting point of ice at normal pressure Tm of the water model is found. Models with a good prediction of the melting temperature of ice Ih, have also good predictions of the three phases coexistence line. Models with a bad prediction of the melting temperature of ice Ih, provide poor estimates of T3. As a rule of thumb, the three phase coexistence line of the methane hydrate at 100 bars for a water-methane force field is located approximately at about 15(7) K above the melting temperature of ice Ih of the considered water model. In summary, when modeling the methane-hydrate, if you are looking for a three phases coexistence line in good agreement with experiment, you need first a water model that describes accurately the melting temperature of ice Ih.

Conde, M. M.; Vega, C.

2013-02-01

342

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 TDPLL is built and simulated in the high-speed VHS-ADC simulation p...

Xuegui Zhu; Zhihong Fu; Xiangfeng Su

2013-01-01

343

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

344

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

345

Juvenile Dermatomyositis Diagnosed by 99mTc-HDP Three-phase Bone Scintigraphy

International Nuclear Information System (INIS)

Juvenile dermatomyositis is a common inflammatory muscle disease of childhood, characterized by weakness in proximal muscles and specific skin rash. In case of juvenile dermatomyositis without characteristic clinical features, non-invasive imaging tools such as 99mTc-HDP three-phase bone scan are very helpful in diagnostic workup of myopathies. We report a case of 13-year old female with juvenile dermatomyositis, in which 99mTc-HDP three-phase bone scan was useful in diagnosis and assessing therapy response

346

Juvenile Dermatomyositis Diagnosed by {sup 99m}Tc-HDP Three-phase Bone Scintigraphy

Energy Technology Data Exchange (ETDEWEB)

Juvenile dermatomyositis is a common inflammatory muscle disease of childhood, characterized by weakness in proximal muscles and specific skin rash. In case of juvenile dermatomyositis without characteristic clinical features, non-invasive imaging tools such as {sup 99m}Tc-HDP three-phase bone scan are very helpful in diagnostic workup of myopathies. We report a case of 13-year old female with juvenile dermatomyositis, in which {sup 99m}Tc-HDP three-phase bone scan was useful in diagnosis and assessing therapy response.

Kim, Ja Hye; Song, Ho Chun; Yoo, Su Ung; Ha, Jung Min; Chong, A Ri; Oh, Jong Ryool; Min, Jung Joon; Bom, Hee Seung; Jeong, Eun Hui; Lee, Min Chul [Chonnam National University Hospital, Gwangju (Korea, Republic of)

2009-12-15

347

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

348

Three-Phase Modulated Pole Machine Topologies Utilizing Mutual Flux Paths

DEFF Research Database (Denmark)

This paper discusses three-phase topologies for modulated pole machines (MPMs). The authors introduce a new threephase topology, which takes advantage of mutual flux paths; this is analyzed using 3-D finite-element methods and compared to a three-phase topology using three single-phase units stacked axially. The results show that the new “combined-phase MPM” exhibits a greater torque density, while offering a reduction in the number of components. The results obtained from two prototypes are also presented to verify the concept; the results show that the “combined-phase” machine could provide both performance and constructional benefits over prior MPM topologies.

Washington, Jamie G.; Atkinson, Glynn J.

2012-01-01

349

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

350

The analysis of magnesium oxide hydration in three-phase reaction system

In order to investigate the magnesium oxide hydration process in gas-liquid-solid (three-phase) reaction system, magnesium hydroxide was prepared by magnesium oxide hydration in liquid-solid (two-phase) and three-phase reaction systems. A semi-empirical model and the classical shrinking core model were used to fit the experimental data. The fitting result shows that both models describe well the hydration process of three-phase system, while only the semi-empirical model right for the hydration process of two-phase system. The characterization of the hydration product using X-Ray diffraction (XRD) and scanning electron microscope (SEM) was performed. The XRD and SEM show hydration process in the two-phase system follows common dissolution/precipitation mechanism. While in the three-phase system, the hydration process undergo MgO dissolution, Mg(OH)2 precipitation, Mg(OH)2 peeling off from MgO particle and leaving behind fresh MgO surface.

Tang, Xiaojia; Guo, Lin; Chen, Chen; Liu, Quan; Li, Tie; Zhu, Yimin

2014-05-01

351

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.)

352

Teaching Qualitative Research for Human Services Students: A Three-Phase Model

Qualitative research is an inherent part of the human services profession, since it emphasizes the great and multifaceted complexity characterizing human experience and the sociocultural context in which humans act. In the department of human services at Emek Yezreel College, Israel, we have developed a three-phase model to ensure a relatively…

Goussinsky, Ruhama; Reshef, Arie; Yanay-Ventura, Galit; Yassour-Borochowitz, Dalit

2011-01-01

353

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

354

A novel adaptive HBCC technique for three-phase shunt APF

Energy Technology Data Exchange (ETDEWEB)

This paper proposes an important improvement of the hysteresis band current control (HBCC) technique for three-phase shunt active power filter (APF) to eliminate harmonics and to compensate the reactive power generated by three-phase rectifier. In this technique, a simple and quick prediction of the hysteresis band is added to a phase-locked-loop (PLL) control to ensure constant switching frequency and synchronization of modulation pulses independently on system parameters. This allows the advantages of quick response, good current tracking accuracy and minimal ripple in three-phase systems. This technique is robust and it is characterized by the simplicity, this aspect is very significant for a practice realization because it constitutes the factors which determine the cost and the reliability of industrial assembly. The proposed technique determines the switching signals of the three-phase shunt APF and the algorithm which is based on the dc bus capacitors voltage regulation using proportional-integral (PI) controller is used to determine the suitable current reference signals. The behavior of the proposed technique has been fully verified by digital simulation, where the obtained results show that the proposed technique can improve shunt APF performances noticeably. (author)

Belhaouchet, N.; Rahmani, L.; Begag, S. [Department of Electrotechnic, Ferhat Abbas University-Setif (Algeria)

2009-07-15

355

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

356

A three-phase model for mixed columnar-equiaxed solidification

A three-phase model for mixed columnar-equiaxed solidification is presented in this article. The three phases are the parent melt as the primary phase, as well as the solidifying columnar dendrites and globular equiaxed grains as two different secondary phases. With an Eulerian approach, the three phases are considered as spatially coupled and interpenetrating continua. The conservation equations of mass, momentum, species, and enthalpy are solved for all three phases. An additional conservation equation for the number density of the equiaxed grains is defined and solved. Nucleation of the equiaxed grains, diffusion-controlled growth of both columnar and equiaxed phases, interphase exchanges, and interactions such as mass transfer during solidification, drag force, solute partitioning at the liquid/solid interface, and release of latent heat are taken into account. Binary steel ingots (Fe-0.34 wt pct C) with two-dimensional (2-D) axis symmetrical and three-dimensional (3-D) geometries as a benchmark were simulated. It is demonstrated that the model can be used to simulate the mixed columnar-equiaxed solidification, including melt convection and grain sedimentation, macrosegregation, columnar-to-equiaxed-transition (CET), and macrostructure distribution. The model was evaluated by comparing it to classical analytical models based on limited one-dimensional (1-D) cases. Satisfactory results were obtained. It is also shown that in order to apply this model for industrial castings, further improvements are still necessary concerning some details.

Wu, Menghuai; Ludwig, Andreas

2006-05-01

357

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

358

International Nuclear Information System (INIS)

The method for simultaneous extraction and back extraction in liquid three-phase system has been worked out. The equipment designed for that process has been also subject of the patent. The interesting component is extracted first to intermediate phase consists of magnetic solvent keeping two extracting phases separately. The intermediate magnetic liquid has been kept in its position using a stable magnet maintained on the surface of the extraction vessel. Then the component pass from intermediate phase to the third phase as a result of back extraction. Mixing in the extraction and back extraction zones is organized by means of rotating shaft going along the whole apparatus. The extraction and back extraction processes occur simultaneously as a result of continuous flow of solvent in their zones. The single extraction back extraction facilities can be joined in larger batteries. 3 figs

359

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

360

DEFF Research Database (Denmark)

Two existing methods to implement resampling modulation technique for modular multilevel converter (MMC) (the sampling frequency is a multiple of the carrier frequency) are: the software solution (using a microcontroller) and the hardware solution (using FPGA). The former has a certain level of inaccuracy in terms of switching instant, while the latter is inflexible with higher cost. In order to overcome these drawbacks, this paper proposes an alternative solution, which uses high frequency saw-tooth carrier and two independent comparators, usually available in microcontrollers, to create the proper switching instances needed for the resampling modulation technique. The software implementation of the proposed phase shifted PWM (PS-PWM) method, and its application in a distributed control system for MMC, are fully discussed in this paper. Simulation and experiment results show that the proposed solution can realize the resampled uniform PWM and provide high effective sampling frequency and low time delay, which is critical for the distributed control of MMC.

Huang, Shaojun; Mathe, Laszlo

2013-01-01

361

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

362

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

363

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

364

Dispersion and holdup in a three-phase fluidized-bed bioreactor

Energy Technology Data Exchange (ETDEWEB)

Axial dispersion and phase holdup measurements were made using electroconductivity in a fermenting fluidized-bed bioreactor (FBR) and in a model nonfermenting three-phase FBR. Multiple axial conductivity probes were used to nonintrusively monitor the bed conductivity. The gas phase holdup was estimated from a ratio of the average bed conductivity and bulk conductivity. The solid fraction in the three-phase FBR can be estimated from the two-phase liquid-solid FBR. The response to a salt pulse was used to estimate the liquid axial dispersion coefficient. Particle Peclet numbers on the order of 10/sup /minus/2/ were estimated as a function of flow rates and compared to literature correlations. 10 refs., 7 figs.

Davison, B.H.

1988-01-01

365

Dispersion and holdup in a three-phase fluidized-bed bioreactor

Energy Technology Data Exchange (ETDEWEB)

Axial dispersion and phase holdup measurements were made using electroconductivity in a fermenting fluidized-bed bioreactor (FBR) and in a model nonfermenting three-phase FBR. Multiple axial conductivity probes were used to nonintrusively monitor the bed conductivity. The gas phase holdup was estimated from a ratio of the average bed conductivity and bulk conductivity. The solid fraction in the three-phase FBR can be estimated from the two-phase liquid-solid FBR. The response to a salt pulse was used to estimate the liquid axial dispersion coefficient. Particle Peclet numbers on the order of 10{sup {minus}2} were estimated as a function of flowrates and compared to literature correlations.

Davison, B.H. (Oak Ridge National Lab., TN (United States))

1989-01-01

366

Modeling of an immobilized-cell three-phase fluidized-bed bioreactor

Energy Technology Data Exchange (ETDEWEB)

A mathematical model of a three-phase, tapered, fluidized-bed bioreactor has been developed. This model includes the effects of the tapered bed, a variable dispersion coefficient, and the concentration profile inside the biocatalyst bead on the reaction rate within the bed. Parameters in this model were obtained by adjusting them, within a realistic range, such that the square of the difference between the values predicted by the model and those obtained experimentally was minimized. The model was found to predict experimentally obtained concentration profiles quite accurately. It also demonstrates the need to include the effects of variable dispersion in three-phase systems where the gas phase is being generated inside the reactor, as the dispersion coefficient varied by more than an order of magnitude across the bed.

Petersen, J.N. [Washington State Univ., Pullman, WA (United States); Davison, B.H. [Oak Ridge National Lab., TN (United States)

1991-12-31

367

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

368

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

369

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

370

Voltage stability studies (VSS) of the electric network is a crucial factor to make the system operate in stable region and to prevent power blackouts. There are several commercial tools available for VSS of electric transmission systems (TS) but not many for distribution systems (DS). With increasing penetration of distributed renewable generations and meshed network within DS, shipboard power system (SPS) and microgrid, these VSS tools need to be extended for DS. Due to inherent characteristic like high R/X ratio, three phase and unbalanced operation, DS or SPS requires different mathematical approach than TS. Unbalanced three phase power flow and continuation power flow tools were developed using current injection and corrector predictor methods in this work for VSS. Maximum loading point for given DS or SPS can be computed using developed tools to guide required preventive and corrective actions. Developed tool was tested and validated for several different test cases.

Toppo, Shilpa

371

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The dynamic modelling principles for typical catalytic three-phase reactors, batch autoclaves and fixed (trickle) beds were described. The models consist of balance equations for the catalyst particles as well as for the bulk phases of gas and liquid. Rate equations, transport models and mass balanc [...] es were coupled to generalized heterogeneous models which were solved with respect to time and space with algorithms suitable for stiff differential equations. The aspects of numerical solution strategies were discussed and the procedure was illustrated with three case studies: hydrogenation of aromatics, hydrogenation of aldehydes and oxidation of ferrosulphate. The case studies revealed the importance of mass transfer resistance inside the catalyst pallets as well as the dynamics of the different phases being present in the reactor. Reliable three-phase reactor simulation and scale-up should be based on dynamic heterogeneous models.

T., Salmi; J., Wärnå; S., Toppinen; M., Rönnholm; J.P., Mikkola.

1023-10-01

372

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

373

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

374

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

375

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

376

Combination of ultrasonic nebulizer and plasma excitation sources for spectrochemical analysis offers desirable features of low detection limits, high sample through out, wide dynamic range of operation, acceptable precision and accuracy, and simultaneous quantitative analytic capabilities. Moreover, the ultrasonic nebulizer does not require sample preconcentration. Recently we have developed a three phase plasma arc (TPPA) for atomic emission spectrochemical analysis. In the present work, to increase the analytical utility of the three-phase plasma system, ultrasonic nebulizer was used for sample introduction. The effects of the argon gas flow rate, current, excitation temperature have been studied. The analytical calibration curves are obtained for Ca, Cr, Fe, Mg and Mn and detection limits have been calculated. The present technique is used to determine the concentration of elements the Ca, Cr, Fe, Mg and Mn in airborne samples.

Ghatass, Z. F.; Roston, G. D.; Mohamed, M. M.

2002-12-01

377

International Nuclear Information System (INIS)

Combination of ultrasonic nebulizer and plasma excitation sources for spectrochemical analysis offers desirable features of low detection limits, high sample through out, wide dynamic range of operation, acceptable precision and accuracy, and simultaneous quantitative analytic capabilities. Moreover, the ultrasonic nebulizer does not require sample preconcentration. Recently we have developed a three phase plasma arc (TPPA) for atomic emission spectrochemical analysis. In the present work, to increase the analytical utility of the three-phase plasma system, ultrasonic nebulizer was used for sample introduction. The effects of the argon gas flow rate, current, excitation temperature have been studied. The analytical calibration curves are obtained for Ca, Cr, Fe, Mg and Mn and detection limits have been calculated. The present technique is used to determine the concentration of elements the Ca, Cr, Fe, Mg and Mn in airborne samples

378

Effect of gas density on the hydrodynamics of bubble columns and three-phase fluidized beds

Energy Technology Data Exchange (ETDEWEB)

The effects of gas density on the hydrodynamics of coarse-particle three-phase fluidized beds was evaluated by employing four gases (helium, air, carbon dioxide and sulphur hexafluoride). Experiments were conducted at ambient temperature and pressure in a bubble column, then in a three-phase fluidized bed in order to provide additional understanding of the relative contribution of particles to the bubble break-up mechanism with increasing gas density. Results showed that the dispersed bubble flow regime was sustained to higher gas velocities and higher gas holdups for the denser gases; apparently due to enhanced bubble breakup and not to the formation of smaller bubbles at the distributor. The effects of gas density on phase holdups was essentially independent of liquid Reynolds number and solids concentration. 32 refs., 2 tabs., 7 figs.

Macchi, A.; Bi, H.; Grace, J. R. [British Columbia University, Dept. of Chemical and Biological Engineering, Vancouver, BC (Canada); McKnight, C. A.; Hackman, L. [Syncrude Canada, Edmonton, AB (Canada)

2003-08-01

379

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

380

Optimisation of an asymmetric three phase-shift distributed feedback semiconductor laser

Abstract This paper shows that accurately optimised asymmetric three phase-shift (3PS)-distributed feedback (DFB) laser structures can strongly improve the stability of the single-longitudinal mode (SLM) operation, described by the mode selectivity and the flatness of the photon density profile, through an extended range of current injection, when compared to optimised symmetric 3PS-DFB structures reported elsewhere. This study reveals its importance in modern high bit-rate opti...

Fernandes, C. A. F.; Morgado, J. A. P.; Boavida, J. B. M.

2009-01-01

381

International Nuclear Information System (INIS)

A 44-year-old female underwent three-phase bone scintigraphy for an evaluation of right hip joint pain. The blood-flow and blood-pool images show a pelvic blush with a photopenic center (doughnut) prior to bladder filling. On the three hour delayed image, the pelvic uptake disappeared. The scintigraphic findings indicated the possibility of an early pregnancy. However, plain radiography demonstrated an intrauterine device. A uterine doughnut developed as a result of photon attenuation of intrauterine device

382

Economic Design of Three-Phase Induction Motor by Particle Swarm Optimization

A Particle Swarm Optimization (PSO) based design of three-phase induction motors are proposed. The induction motor design is treated as a non-linear and multivariable constrained optimization problem. The annual material cost and the total annual cost of the motor are chosen as two different objective functions. The PSO is used to find a set of optimal design variables of the motor which are then used to predict performance indices and the objective functions. The proposed method is demonstra...

Srikrishna Subramanian; Ramachandran Bhuvaneswari; Sakthivel, Vadugapalayam P.

2010-01-01

383

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

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

2009-01-01

384

Three-phase full-wave rectifier study with experimental measurements

Energy Technology Data Exchange (ETDEWEB)

The present paper is an experimental study of the harmonic absorbed currents by three-phase rectifiers. Laboratory tests have been performed with a rectifier to characterize its absorbed harmonic currents (magnitude and phase angle). From these results, a database that characterizes rectifier harmonic behavior experimentally and allows the rectifier currents to be easily calculated is proposed. The database applicability is experimentally studied in two laboratory tests. The results are validated with PSpice simulations. (author)

Sainz, Luis; Mesas, Juan Jose [Department of Electrical Engineering, ETSEIB-UPC, Av. Diagonal 647, 08028 Barcelona (Spain); Ferrer, Albert [Department of Applied Mathematics I, EPSEB-UPC, Av. Doctor Maranon, 44-50, 08028 Barcelona (Spain)

2009-04-15

385

Renewable Distributed Generation Models in Three-Phase Load Flow Analysis for Smart Grid

The paper presents renewable distributed generationÂ (RDG) models as three-phase resource in load flow computation and analyzes their effect when they are connected in composite networks. The RDG models that have been considered comprise of photovoltaic (PV) and wind turbine generation (WTG). The voltage-controlled node and complex power injection node are used in the models. These improvement models are suitable for smart grid power system analysis. The combination of IEEE transmission an...

Nor, K. M.; Syafii Ghazali

2013-01-01

386

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

387

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

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 str...

Salmi T.; Wärnå J.; Toppinen S.; Rönnholm M.; Mikkola J.P.

2000-01-01

388

Power Controllability of Three-phase Converter with Unbalanced AC Source

Three-phase DC-AC power converters suffer from power oscillation and overcurrentt problems in case of unbalanced AC source voltage that can be caused by grid/generator faults. Existing solutions to handle these problems are properly selecting and controlling the positive and negative sequence currents. In this work a new series of control strategies which utilize the zero-sequence components are proposed to enhance the power control ability under this adverse conditions. It is concluded that ...

Ma, Ke; Liserre, Marco; Blaabjerg, Frede

2013-01-01

389

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

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 thr...

Shuhua Jiang

2011-01-01

390

Simulation Of Three-Phase Distillation Column Using Bubble Point And (^-0 Approach

Most of organic compounds are partially miscible in water and due to their solubility criteria split into two liquid phases. So design of equipments that separate two liquid phase systems differ from one liquid phase system equipments. A mathematical model and a computer program have been developed to simulate three-phase distillation columns. The proposed procedure is based on linearization of equations and solving them by Newton-Raphson method. Average liquid compositions are chosen as i...

Lashkari, Siamak

1995-01-01

391

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

392

The traditional large electroslag remelting furnaces have many shortages, such as high short-network impedance and inductance, long maintenance time for electrode replacement, low stiffness of driveline, and low control accuracy of remelting speed. The present research was aimed to solve these problems through structure modification and constant remelting speed control for a 120-t electroslag remelting (ESR) furnace. Based on the technique of three-phase double electrodes in series, the short...

Wang Changzhou; Song Jinchun

2012-01-01

393

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

394

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

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...

Ajay Kumar Maurya; Chauhan, Yogesh K.

2012-01-01

395

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

396

Three phase four wire shunt active power filter from theory to industrial facility tests

Non-linear loads are very common in present industrial facilities, office buildings and even in our homes. This loads present several Power Quality problems to the electrical grid. The conventional solutions do not solve these problems in a suitable way. Therefore, it is necessary to find new solutions such as Active Power Filters. This paper presents and discusses the main steps that are necessary to implement a Three Phase Four Wire Shunt Active Power Filte...

Exposto, Bruno; Gonc?alves, Henrique; Pinto, J. G.; Afonso, Joa?o L.; Couto, Carlos

2011-01-01

397

Analysis of RF conducted emission due to PWM and resonant DC-DC converters

Energy Technology Data Exchange (ETDEWEB)

Analysis and modeling of common mode conducted ElectroMagnetic Interference (EMI) in the Radio Frequency (RF) range (10 KHZ--30MHZ) of a ZVT (DC-DC boost Zero Voltage Transition) PWM converter and a conventional PWM (DC-DC boost) converter are compared. Noise signal measurement is carried out by means of a LISN (Line Impedance Stabilization Network). To compute the noise spectrum of LISN output in RF range, direct simulation of equivalent noise circuits is implemented as well as an analysis in the frequency domain.

Mahdavi, J. [Sharif Univ. of Technology, Tehran (Iran, Islamic Republic of). Dept. of Electrical Engineering; Shahintabe, A. [Islamic Azad Univ., Tehran (Iran, Islamic Republic of). Dept. of Electrical Engineering; Farhadi, A. [Electric Power Research Center, Tehran (Iran, Islamic Republic of). Dept. of Electronics

1995-12-31

398

Elimination of output voltage oscillations in DC-DC converter using PWM with PI controller

Directory of Open Access Journals (Sweden)

Full Text Available In this paper the SIMULINK model of a PWM controlled DC-DC converter is modeled using switching function concept to control the speed of the DC motor. The presence of the voltage oscillation cycles due to higher switching frequency in the DC-DC converter is identified. The effect of these oscillations on the output voltage of the converter, Armature current, Developed torque and Speed of the DC motor is analyzed. In order to minimize the oscillation cycles the PI controller is proposed in the PWM controller.

Sreenivasappa Veeranna Bhupasandra

2010-01-01

399

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

400

Synchronized PWM Scheme for Dual Inverter-Fed Drives with Zero Common-Mode Voltages

DEFF Research Database (Denmark)

Abstract - Novel method of direct synchronized pulsewidth modulation is applied for control of a dual inverter-fed opened winding induction motor drive with zero common-mode voltages. New strategy and algorithms of synchronized PWM provide symmetry of the phase voltage of the system during the whole control range including the zone of overmodulation. Spectra of the phase voltage do not contain even harmonics and sub-harmonics (combined harmonics), which is especially important for the drive systems with increased power rating. Simulations gave the behaviour of dual inverter-fed system with the proposed synchronized PWM scheme.

Oleschuk, Valentin; Blaabjerg, Frede

2005-01-01

401

Soft Switching Full-Bridge PWM DC/DC Converter Using Secondary Snubber

Directory of Open Access Journals (Sweden)

Full Text Available A novel full-bridge PWM DC/DCconverter with controlled secondary side rectifier usingsecondary snubber is presented in this paper.Limitation of the circulating current as well as softswitching for all power switches of the inverter isachieved for full load range from no-load to shortcircuit by using controlled rectifier and snubber on thesecondary side. Phase shift PWM control strategy isused for the converter. The principle of operation isexplained and analyzed and the experimental resultson a 1kW, 50 kHz laboratory model of the converterare presented.

Jaroslav Dudrik

2009-05-01

402

Directory of Open Access Journals (Sweden)

Full Text Available The aim of the study is to develop a simple and direct approach for unbalanced radial distribution system three-phase load flow solution .The special topological characteristics of unbalanced radial distribution networks have been fully utilized to make the direct three phase load flow solution possible. Two developed matrices-the node-injection to line section-current matrix and the line section-current to node-voltage matrix - and a simple matrix multiplication are used to obtain the three phase load flow solution. Due to the distinctive solution techniques of the proposed method, the time-consuming Lower Upper decomposition and forwardbackward substitution of the Jacobian matrix or admittance matrix required in the traditional load flow methods became not necessary. Therefore, the proposed method is observed as robust and time-efficient. Results obtained on 8 node and IEEE 13 node test systems demonstrate the validity of the proposed method. The proposed method has got good potential for the usage in distribution automation applications.

J.B.V. Subrahmanyam

2010-08-01

403

Measurement of Reactive Power in Three-Phase Electric Power Systems by Use of Walsh Functions

Directory of Open Access Journals (Sweden)

Full Text Available Normal 0 false false false MicrosoftInternetExplorer4 Normal 0 false false false MicrosoftInternetExplorer4 Normal 0 false false false MicrosoftInternetExplorer4 This paper presents a new method for measuring of three-phase reactive power (RP in three-phase systems. Extraction of three-phase reactive power RP from entire instantaneous power signal is achieved by multiplication the phase instantaneous powers with the Walsh function(WF. This method simplifies the multiplication procedure required for the evaluation the tree-phase reactive power components due to the use of the peculiar properties of the WF. In contrast to the existing methods involving phase shift operation between the input voltage and current signals proposed measurement approach does not require the phase shift of the phase current signals to the 90 degrees with respect to the voltage signals. Limitations and proposals for future performance enhancements of the suggested method are also discussed. Validity and effectiveness of the suggested method have been tested by use of a simulation tools developed on the base of “Matlab 6.5”. The results obtained demonstrate that the computational demands can be substantially reduced by using the proposed method.

Adalet Abiyev

2010-12-01

404

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

405

Energy Technology Data Exchange (ETDEWEB)

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. (author)

Mahato, S.N.; Sharma, M.P. [Alternate Hydro Energy Centre, Indian Institute of Technology, Roorkee 247 667 (India); Singh, S.P. [Department of Electrical Engineering, Indian Institute of Technology, Roorkee 247 667 (India)

2008-05-15

406

Energy Technology Data Exchange (ETDEWEB)

To determine the number of multiple alternating layers of liver abscess, and changes in this number, as revealed by spiral CT, and to ascertain which factors are related to changes occurring during the three phase of this modality. Using three-phase sprial CT imagingewe studied 26 cases of liver abscess (pyogenic: amebi = 23:3). The number of layers comprising the abscess, as seen on postcontrast CT scans, was determined during the arterial (30sec), portal (70sec),and delayed (220sec) phase, and all cases were assigned to one of to groups according to changes in the number of layers observed during the three phases. With regard to underlying disease, the two groups were compared in terms of the presence of abscess and of diabetes mellitus, CT interval (time from oneset of symptoms to CT scanning), microbial agent (pyogenic vs. amebic), and the largest diameter of abscess as revealed by CT. Except in one case, three or four alternating layers (in 13(50%) and 7(27%) cases, respectively) were seen only during the arterial and portal phase. During each of the three phase and especially the delayed phase, where it was present in 25 of cases (96%)-two alternating layers (2:2:2) was the most common pattern, with a 3:3:3 pattern occurring in one case. All 12 cases (46%) in the unchanging-layer group showed one of three two patterns. All changing-layer group cases (14;54%) demonstrated three or four layers during the arterial and portal phase but only two during the delayed phase. The CT interval was the only significantly different factor between the two groups. During the first week, the number of cases in the unchanging-layer group was much higher than in the changing layergroup (86%, 14%), but during the second week this situation reversed (25%, 75%). Our study reveals that on three-phase dynamic CT images, a characteristic enhancement feature of liver abscess is three or four layers during the arterial and portal phases, with reduction to two layers during the delayed phase. This change, as revealed by sprial CT, is rare during the week following the oneset of symptoms, but common during the second week.

Kwon, Ju Bae; Kim, Yong Soo; Rhim, Hyun Chul; Koh, Byung Hee; Cho, On Koo; Kim, Bong Soo; Park, Dong Woo; Park, Choong Ki [Hanyang Univ. College of Medicine, Seoul (Korea, Republic of)

2001-01-01

407

Nodular hepatocellular carcinoma : contrast enhancement patterns on three - phase spiral CT

International Nuclear Information System (INIS)

To evaluate contrast enhancement patterns of nodular hepatocellular carcinomas (HCCs) on three-phase spiral CT. A retrospective analysis of contrast enhancement patterns was performed in 48 patients with HCC. Three-phase dynamic CT images of hepatic arterial dominant phase, portal dominant phase, and delayed phase were obtained at 30, 65 and 360 seconds after the initiation of injection of contrast material, respectively. Iodized-oil CT was performed two weeks after angiography and infusion of iodized-oil. Masses were divided into three groups, according to size ; 1-20mm (n=34), 21-40mm (n=26), and over 40mm (n=19). Contrast enhancement patterns of tumors compared with attenuation of surrounding liver parenchyma, were cheracterized as one of four types, as follows : high, iso, low and mixed attenuation. Seventy-three of 79 HCC nodules detected on iodized-oil CT (92%) were detected on three-phase spiral CT. In the 1-20mm group, masses showed high-attenuation in the arterial dominant phase(19/34, 55.9%), and iso-attenuation in the portal dominant phase(16/34, 47.1 %) and delayed phase(18/34, 52.9%). In the 21-40mm group, masses showed high-attenuation in the arterial dominant phase(21/26, 80.8 %), low-attenuation in the portal dominant phase(13/26, 50%) and delayed phase(21/26, 80.8 %). In the over 40m group, the masses showed mixed-attenuation in the arterial dominant phase(9/19, 47.4%), low-attenuation in the portal dominant phase(12/19, 63.2%), and delayed phase(16/1hase(12/19, 63.2%), and delayed phase(16/19, 84.2 %). The most common enhancement pattern was high(arterial dominant)-iso(portal dominant)-iso(delayed) in the 1-20 mm group (8/34, 23.5 %), high-low-low in the group 21-40 mm (8/26, 30.8%), and mixed-low-low in the over 40mm group (5/19, 26.3%). Hepatocellular carcinomas showed variable enhancing patterns according to the size of the tumor on three-phase spiral CT. Understanding these enhancing characteristics of HCCs on three-phase spiral CT may be helpful in their diagnosis

408

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

409

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

410

Three phase matrix converters have received considerable attention in recent years because they may become a good alternative to voltage-source inverter pulse width-modulation (VSI-PWM) converters. In fact, the matrix converter provides bidirectional power flow, sinusoidal input/output waveforms, and controllable input power factor. Furthermore, the matrix converter allows a compact design due to the lack of dc-link capacitors for energy storage. The matrix converters are more sensitive to in...

Joshi R; Gupta R.; Wadhwani A

2007-01-01

411

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

412

Energy Technology Data Exchange (ETDEWEB)

This paper presents a novel, self-regulated, self-excited, single-phase induction generator with a three-phase auxiliary winding. Its steady-state performance is theoretically analyzed using the method of symmetrical coordinates, and the results are confirmed through experiments. In addition to the advantage of balanced three-phase excitation, the new generator has good winding utilisation. (orig.)

Fukami, Tadashi; Hanaoka, Ryoichi; Miyamoto, Toshio [Kanazawa Institute of Technology, Division of Electrical Engineering, Ishikawa (Japan); Naoe, Nobuyuki [Kanazawa Technical College, Department of Electrical Engineering, Ishikawa (Japan)

2000-08-01

413

Research on the Novel Charge-discharge System of Storage Battery

At present, the issue of low power factor and harmonic pollution in traditional charge-discharge system is serious, with the development of PWM rectifier technology, A novel main circuit topology of charge-discharge system with a three-phase voltage source PWM rectifier (VSR) and Bi-directional DC-DC converter are applied in this paper. It can be used as battery charging power supply, but also as a discharge load of battery. Regenerative energy is feedback to power grid and the purpose of ene...

Zheng Zheng; Wenbin Zhou; Hui He

2013-01-01

414

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

415

The comparison of radiosensitivity of human lymphocytes stimulated with PHA Con A and PWM

International Nuclear Information System (INIS)

The transformation, DNA strand breaks and its repair ability in human peripheral blood lymphocytes stimulated with PHA, Con A and PWM were respectively assessed following exposure to 60Co gamma rays by 3H-thymidine uptake and hydroxylapatite chromatography. It was showed the transformation of lymphocytes stimulated with PHA, Con A and PWM were suppressed by gamma rays and the dose-effect curves were biphase within the range of 0?8 Gy. The lymphocytes stimulated with PWM was the most resistant to gamma rays. The extent of DNA strand breaks in lymphocytes induced by gamma rays was linearly related to the dose within the range of 0?30 Gy and was identical in three kinds of lymphocytes. After post-irradiation incubation of 37 deg C, the DNA strand breaks could be repaired incompletely and after maxium repair the strand breaks were observed again. The repair ratio of strand breaks in the lymphocytes stimulated with PWM was the highest in the cells with three mitogens. The results showed that the difference of radiation effect on the transformation is probably related to the repair ability of DNA strand breaks

416

Sensorless Position Measurement Based on PWM Eddy Current Variation for Switched Reluctance Motor

This paper proposes a new method for indirect sensing of the rotor position in a switched reluctance motor. The method operates with the rotor eddy current losses produced by the PWM converter switching, regardless of magnetic saturation. Experimental results concerning sensivity and performances are schown in a 6/4 30W 3000rpm SRM.

Laurent, Philippe; Multon, Bernard; Hoang, Emmanuel; Gabsi, Mohamed

1994-01-01

417

Analytical Modelling of Periodical PWM Converter Fed R-L Load.

Czech Academy of Sciences Publication Activity Database

Orlando, Florida : International Institute of Informatics and Systemics, 2003, s. 406-411. ISBN 980- 6560 -01-9. [World Multiconference on Systemics, Cybernetics and Informatics - SCI 2003 /7./. Orlando, Florida (US), 27.07.2003-30.07.2003] Institutional research plan: CEZ:AV0Z2057903 Keywords : analytical model * periodical PWM * Laplace transform Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

Klíma, J.; Schreier, Lud?k

418

Three-phase metal kinetics in terrestrial invertebrates exposed to high metal concentrations

Energy Technology Data Exchange (ETDEWEB)

Models of metal toxicokinetics are critically evaluated using both newly generated data in the NoMiracle project as well as those originating from older studies. The analysis showed that the most frequently used one-compartment two-phase toxicokinetic model, with one assimilation and one elimination rate constant, does not describe correctly certain data sets pertaining particularly to the pattern of assimilation of trace elements. Using nickel toxicokinetics in carabid beetles and earthworms as examples, we showed that Ni in fact exhibits a three-phase kinetics with a short phase of fast metal accumulation immediately after exposure, followed by partial elimination to an equilibrium concentration at a later stage of a metal exposure phase, and by final elimination upon transfer to an uncontaminated food/soil. A similar phenomenon was also found for data on cadmium kinetics in ground beetles and copper kinetics in earthworms in data already published in the literature that was not accounted for in the earlier analysis of the data. The three-phase model suggests that the physiology of controlling body metal concentrations can change shortly after exposure, at least in some cases, by increasing the elimination rate and/or decreasing metal assimilation. Hence, the three-phase model, that allows for different assimilation and/or elimination rates in different phases of exposure to a toxicant, may provide insight into temporal changes in the physiology of metal handling. Consequently, this alternative model should always be tested when describing metal toxicokinetics when temporal patterns of internal metal concentration exhibit an initial 'overshoot' in body metal concentrations.

Laskowski, Ryszard, E-mail: ryszard.laskowski@uj.edu.pl [Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Krakow (Poland); Bednarska, Agnieszka J. [Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Krakow (Poland); Spurgeon, David; Svendsen, Claus [Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxon, OX10 8BB (United Kingdom); Gestel, Cornelis A.M. van [Institute of Ecological Science, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands)

2010-08-15

419

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 second half year (April 1, 2001-September 30, 2001) of the fourth project year budget period (October 1, 2000-September 30, 2001). An executive summary is presented initially followed by the tasks of the current budget period. Then, detailed description of the experimental and modeling investigations are presented. Subsequently, the technical and scientific results of the activities of this project period are presented with some discussions. The findings of this investigation are summarized in the ''Conclusions'' section followed by relevant references. The fourth project year activities are divided into three main parts, which are carried out in parallel. The first part is continuation of the experimental program that includes a study of the oil/water two-phase behavior at high pressures and control system development for the three-phase GLCC{copyright}. This investigation will be eventually extended for three-phase flow. The second part consists of the development of a simplified mechanistic model incorporating the experimental results and behavior of dispersion of oil in water and water in oil. This will provide an insight into the hydrodynamic flow behavior and serve as the design tool for the industry. Although useful for sizing GLCC{copyright} for proven applications, the mechanistic model will not provide detailed hydrodynamic flow behavior information needed to screen new geometric variations or to study the effect of fluid property variations. Therefore, in the third part, the more rigorous approach of computational fluid dynamics (CFD) will be utilized. Multidimensional multiphase flow simulation at high pressures and for real crude conditions will provide much greater depth into the understanding of the physical phenomena and the mathematical analysis of three-phase GLCC{copyright} design and performance.

Dr. Ram S. Mohan; Dr. Ovadia Shoham

2001-10-30

420

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

421

HARMONIC ANALYSIS OF SVPWM INVERTER USING MULTIPLE-PULSES METHOD

Directory of Open Access Journals (Sweden)

Full Text Available Space Vector Modulation (SVM technique is a popular and an important PWM technique for three phases voltage source inverter in the control of Induction Motor. In this study harmonic analysis of Space Vector PWM (SVPWM is investigated using multiple-pulses method. Multiple-Pulses method calculates the Fourier coefficients of individual positive and negative pulses of the output PWM waveform and adds them together using the principle of superposition to calculate the Fourier coefficients of the all PWM output signal. Harmonic magnitudes can be calculated directly by this method without linearization, using look-up tables or Bessel functions. In this study, the results obtained in the application of SVPWM for values of variable parameters are compared with the results obtained with the multiple-pulses method.

Mehmet YUMURTACI

2009-01-01

422

Modelling and Simulation of SVPWM Inverter Fed Permanent Magnet Brushless DC Motor Drive

Directory of Open Access Journals (Sweden)

Full Text Available Variable speed drives with Pulse Width Modulation are increasingly applied in many new industrial applications for more efficient performance. Recently, developments in power electronics and semiconductor technology have lead to widespread use of power electronic converters in the power electronic systems. A number of Pulse width modulation (PWM schemes are used to obtain variable voltage and frequency supply from a three-phase voltage source inverter. Among the different PWM techniques proposed for voltage fed inverters, the sinusoidal PWM technique has been popularly accepted. But there is an increasing trend of using space vector PWM (SVPWM because of their easier digital realization, reduced harmonics, reduced switching losses and better dc bus utilization. This paper focuses on step by step development of SVPWM implemented on a PMBLDC motor. Simulation results are obtained using MATLAB/Simulink environment for effectiveness of the study.

DEVISREE SASI

2013-05-01

423

Automatic start control for a three-phase electric motor using infrared sensors

We introduce equipment for the automatic activation of a three-phase electric motor (1Hp, 3A, 240V AC) using 2 infrared sensors monitored by a Microchip microcontroller PIC16F62x@4Mhz for the control of a filling system. This project was carried out to Fabrica de Chocolates y Dulces Costanzo, where the automatization of cacao grain supply was required for a machine in charge of cleaning the cacao from its rind. This process demanded the monitoring of the filling level to avoid the spill of toasted cacao.

Echenique Lima, Mario; Ramírez Arenas, Francisco; Rodríguez Pedroza, Griselda

2006-02-01

424

Coriolis mass flow metering for three-phase flow: A case study

Previous work has described the use of Coriolis mass flow metering for two-phase (gas/liquid) flow. As the Coriolis meter provides both mass flow and density measurements, it is possible to resolve the mass flows of the gas and liquid in a two-phase mixture if their respective densities are known. To apply Coriolis metering to a three-phase (oil/water/gas) mixture, an additional measurement is required. In the work described in this paper, a water cut meter is used to indicate what proportion...

Henry, M.; Tombs, M.; Zamora, M.; Zhou, F.

2013-01-01

425

Direct torque control of six-phase induction motors using three-phase matrix converter

International Nuclear Information System (INIS)

This paper presents a new direct torque control (DTC) method for six-phase induction motor (SPIM). In the proposed method, direct torque and flux control are applied to the SPIM using matrix converter with the conventional three-phase source as its input. The new DTC scheme for SPIM benefits the advantages of both DTC and matrix converter, such as unity power factor and absence of dc-link. The simulation results show the effectiveness of the proposed method in both dynamic and steady state response.

426

Fault Detection, Isolation and Control Reconfiguration of Three-Phase PMSM Drives

This paper deals with on-line software fault detection and isolation method for a drive composed of a fourleg inverter and a three-phase permanent magnet synchronous machine. The considered faults are single-phase open-circuit and current sensor outage. The method is based on the monitoring of the abc currents with phase-locked loops and the 'CUSUM' algorithm for the decision system. The impact of the considered faults is examined: first, in case there is no modification of the control and th...

Meinguet, Fabien; Kestelyn, Xavier; Semail, Eric; Gyselinck, Johan

2011-01-01

427

Direct torque control of six-phase induction motors using three-phase matrix converter

Energy Technology Data Exchange (ETDEWEB)

This paper presents a new direct torque control (DTC) method for six-phase induction motor (SPIM). In the proposed method, direct torque and flux control are applied to the SPIM using matrix converter with the conventional three-phase source as its input. The new DTC scheme for SPIM benefits the advantages of both DTC and matrix converter, such as unity power factor and absence of dc-link. The simulation results show the effectiveness of the proposed method in both dynamic and steady state response.

Talaeizadeh, V., E-mail: valitalaeezadeh@yahoo.co [Shahid Chamran University of Ahvaz, Ahvaz (Iran, Islamic Republic of); Kianinezhad, R.; Seyfossadat, S.G. [Shahid Chamran University of Ahvaz, Ahvaz (Iran, Islamic Republic of); Shayanfar, H.A. [The Center of Excellence for Power System Automation and Operation, Department of Electrical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

2010-12-15

428

A laboratory grid simulator based on three-phase four-leg inverter : Design and implementation

DEFF Research Database (Denmark)

This paper presents the design and implementation of a laboratory grid simulator which is used to test the grid-connected devices according to the strict standards. Three-phase four-leg inverter with direct voltage control in Natural Frame is adopted in this grid simulator, which significantly reduces the computing and realizing complexities. Proportional and resonant controller is utilized to regulate the output voltage. Furthermore, various feedback variables in the inner control loop are discussed and compared. The capacitor current feedback was identified to guarantee better stability and power quality. Experimental results verify the functionality and performances of the designed grid simulator.

Li, Fei; Wang, Xiongfei

2011-01-01

429

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

430

Experimental and Computational Studies of Hydrodynamics in Three-Phase and Two-Phase Fluidized Beds

The objective of the present study was to investigate the hydrodynamics of three-phase fluidized beds, their rheology, and experimentally verify a predictive three fluid hydrodynamic model developed at the Illinois Institute of Technology, Chicago. The recent thorough reviews by L. S. Fan, B. L. Tarmy and C. A. Coulaloglou (1990) show that there exist no such models in the literature. The IIT hydrodynamic model computes the phase velocities and the volume fractions of gas, liquid, and particulate phases. Model verification involves a comparison of these computed velocities and volume fractions to experimental values. In this thesis, a three fluid model is presented. The input into the model can be particulate viscosities either measured with a Brookfield viscometer or derived using the mathematical techniques of kinetic theory of granular flows pioneered by Savage and others. The computer simulation of a three-phase fluidized bed in an asymmetric mode qualitatively predicts the gas, liquid and solid hold-ups (volume fractions) and flow patterns in the industrially important churn-turbulent (bubbly coalesced) regimes. The computations in a fluidized bed with a symmetric distributor incorrectly showed no bubble coalescence. A combination of X-ray and gamma -ray densitometers was used to measure the solids and the liquid volume fractions in a two dimensional bed in the bubble coalesced regime. There is a good agreement between the theory for an asymmetric distributor and the experiments. The porosity fluctuation signals inside two phase and three phase fluidized beds were detected by using a gamma-ray absorption technique and analyzed by means of the fast Fourier transform (FFT) power spectrum method. The measurements indicated that the bubble coalescence and break-up could be detected by using such techniques. The experimental and simulation porosity fluctuations and bubble frequencies show a fair comparison. A high resolution micro-imaging/measuring system apparatus was used to measure instantaneous and time averaged particle velocities. The fluctuations of particle velocities around their average values were found to be approximately Maxwellian. The measured time averaged velocities compare well with the predicted velocities for an asymmetric distributor used in this study. A Brookfield viscometer was used to measure the "apparent" bed viscosity in two three-phase fluidized beds. The viscosities were also calculated from measurements of particle oscillations (granular temperatures) using a high resolution micro-imaging/measuring system. To obtain these viscosities a dense phase kinetic theory formula derived in D. Gidaspow's book (1994) was used. There is an excellent agreement between the macroscopically measured viscosities using a Brookfield viscometer and those computed from particle fluctuations and collisions using kinetic theory.

Bahary, Mitra

431

Vector Controlled Two Phase Induction Motor and To A Three Phase Induction Motor

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents vector controlled of single phase induction motor. some problems are with vector controlled SPIM.As SPIM’s are typically to maintain speed and also about the complex implementation of vector controlled SPIM.the implemantion of the proposed vector controlled TPIM compared to the vector controlled SPIM. The general modal sutable for vector control of the unsymmentrical two phase induction motor and also stator flux oriented controlled strategies are analized. the comparative performance of both has been presented in this work with help of a practical three phase motor.

K.krishna Rao (PG student

2014-12-01

432

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 microgrid hierarchical control structure. By sending information through low-bandwidth communication links to the primary control level, the required unbalanced factors at sensitive buses are achieved. Also, negative and zero sequence equivalent circuits and unbalance compensation principle are derived. Finally, real-time hardware-in-the-loop results show the feasibility of the proposed approach for different islanded scenarios.

Tang, Fen; Zhou, Xiao

2014-01-01

433

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

434

Three-phase x-ray high voltage generator, model HD150B-30

International Nuclear Information System (INIS)

A new general-purpose three-phase x-ray high voltage generator equipped with high grade functions that have been used only in the finest models has been developed. It has much enhanced ease-of-operation and the output performance, and is available at a reasonable cost. In designing the generator, careful consideration was also paid for the quality assurancee of the generator. For example, several kinds of built-in monitoring circuit to test the high voltage output and the status of working condition are provided. (author)

435

A parametric study on unbalanced three phase islanded microgrids with inverter interfaced units

DEFF Research Database (Denmark)

In this paper, the solution of the power flow for unbalanced three phase microgrids systems is proposed. The study aims at the integration of inverter interfaced units using the control law used for primary voltage and frequency regulation, so as to take into account possible small variations of these parameters to account for sudden load changes. The proposed study deals with unbalanced systems which is the typical case of small distribution systems and shows how the power losses term varies as the regulators parameters vary as well, thus showing that these are sensitive parameters that could have an important role in optimal management of such systems.

Sanseverino, Eleonora Riva; Quang, Ninh Nguyen

2013-01-01

436

Characterization of a Three-Phase Magnetically Stabilized Fluidized Bed Bioreactor

Three-phase fluidized bed systems have many desirable properties such as excellent phase contacting, low pressure drops, reduced plugging, and reduced shear. However, at high gas flow rates, bubbles coalescence tends to reduce phase contacting, and increase shear and turbulence. Studies have shown that application of a magnetic field to two -phase fluidized beds can reduce or eliminate this undesirable behavior. The focus of this study was to examine the properties of a three-phase fluidized bed with an applied magnetic field. Bed regimes, gas void fraction, axial liquid mixing and gas-to-liquid mass transfer were examined in this study. Six bed regimes were identified: random, chain, chain-channel, destabilized, channel, and frozen. Bed properties varied markedly from regime to regime. Local gas void fraction was found to increase 200% in the frozen regime. The axial dispersion coefficient, a measure of liquid mixing, decreased 400% in the chain-channel regimes for low liquid velocities, and gas to liquid mass transfer increased by 30% in the chain-channel and destabilized regimes. A mathematical model was also developed to predict the effect of intraparticle tracer diffusion into the solid phase on measurement of axial mixing. The mathematical model allowed development of criteria to determine when intraparticle diffusion could be ignored relative to effects of dispersion and convection, and allowed correction of experimental measurements.

Thompson, Vicki Sue

1993-01-01

437

Plutonium partitioning in three-phase systems with water, granite grains, and different colloids.

Low-solubility contaminants with high affinity for colloid surfaces may form colloid-associated species. The mobile characteristics of this species are, however, ignored by the traditional sorption/distribution experiments in which colloidal species contributed to the immobile fraction of the contaminants retained on the solids as a result of centrifugation or ultrafiltration procedures. The mobility of the contaminants in subsurface environments might be underestimated accordingly. Our results show that colloidal species of (239)Pu in three-phase systems remained the highest percentages in comparison to both the dissolved species and the immobile species retained on the granite grains (solid phase), although the relative fraction of these three species depended on the colloid types. The real solid/liquid distribution coefficients (K s/d) experimentally determined were generally smaller than the traditional K s/d (i.e., the K s+c/d in this study) by ~1,000 mL/g for the three-phase systems with the mineral colloids (granite particle, soil colloid, or kaolinite colloid). For the humic acid system, the traditional K s/d was 140 mL/g, whereas the real K s/d was approximately zero. The deviations from the real solid/liquid K s/d were caused by the artificially increased immobile fraction of Pu. One has to be cautious in using K s/d-based transport models to predict the fate and transport of Pu in the environment. PMID:24562456

Xie, Jinchuan; Lin, Jianfeng; Zhou, Xiaohua; Li, Mei; Zhou, Guoqing

2014-06-01

438

Superconducting properties of barium in three phases under high pressure from first principles

International Nuclear Information System (INIS)

Electron—phonon coupling (EPC) in the three high-pressure phases of Ba is investigated using a pseudopotential plane-wave method based on density functional perturbation theory. The calculated values of superconducting critical temperature Tc of Ba—I and Ba—II under pressure are consistent well with the trends observed experimentally. Moreover, Ba—V is found to be superconducting with a maximum Tc exceeding 7.8 K at 45 GPa. With the increase of pressure, the values of Tc increase in Ba I and Ba—II but the value of Tc decreases in Ba—V. For Ba—I at pressures below 2 GPa, the increases of logarithmic average frequency ?log and electron—phonon coupling parameters ? both contribute to the enhancement of Tc. For all the three phases at pressures above 2 GPa, Tc is found to be primarily determined by ?. Further investigation reveals that for all the three phases, the change in ? with pressure can be explained mainly by change in the phonon frequency Thus for Ba—II and Ba—V, although they exhibit completely different superconducting behaviors, their superconductivities have the same origin; the pressure dependence of Tc is determined finally by the pressure dependence of phonon frequency. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

439

Molecular dynamics simulation of CO2 hydrates: Prediction of three phase coexistence line

The three phase equilibrium line (hydrate-liquid water-liquid carbon dioxide) has been estimated for the water + carbon dioxide binary mixture using molecular dynamics simulation and the direct coexistence technique. Both molecules have been represented using rigid nonpolarizable models. TIP4P/2005 and TIP4P/Ice were used for the case of water, while carbon dioxide was considered as a three center linear molecule with the parameterizations of MSM, EPM2, TraPPE, and ZD. The influence of the initial guest occupancy fraction on the hydrate stability has been analyzed first in order to determine the optimal starting configuration for the simulations, paying attention to the influence of the two different cells existing in the sI hydrate structure. The three phase coexistence temperature was then determined for a pressure range from 2 to 500 MPa. The qualitative shape of the equilibrium curve estimated is correct, including the high pressure temperature maximum that determines the hydrate re-entrant behaviour. However, in order to obtain quantitative agreement with experimental results, a positive deviation from the classical Lorentz-Berthelot combining rules must be considered.

Míguez, J. M.; Conde, M. M.; Torré, J.-P.; Blas, F. J.; Piñeiro, M. M.; Vega, C.

2015-03-01

440

Measurement and PC-SAFT modelling of three-phase behaviour.

Modelling of multi-component systems with complex interactions is an ongoing challenge in thermodynamics due to their great relevance in industry and academia. Systems that build three liquid phases are found in many interesting applications (separation processes, triphasic catalysis…). Among them, the surfactant flooding method for enhanced oil recovery is noticeable. In this method, a stable solution of water, surfactants, co-surfactants, salts and other components is injected into the reservoir. The optimal formulation of this surfactant system is associated with a three-phase behaviour in which the interfacial tension becomes significantly low. In this work, the PC-SAFT equation of state was used for the first time to predict the equilibrium involved in triphasic systems using solely pure-component parameters. The model without any fitting parameter was able to predict the three-phase behaviour. A great agreement between experimental and predicted compositions for (water + [C10mim][NTf2] + n-dodecane) and (water + [C12mim][NTf2] + n-dodecane) ternary systems at 298.15 K and atmospheric pressure was found. At 348.15 K slightly higher deviations were found, which can be compensated by the introduction of just one binary interaction parameter. The success of this achievement could mean an important advancement in upstream oil operations, enabling a faster and cheaper method to carry out an initial screening of potential surfactants. PMID:25464376

Rodríguez-Palmeiro, Iago; Rodríguez, Oscar; Soto, Ana; Held, Christoph

2015-01-21

441

Three-phase interactions and interfacial transport phenomena in coacervate/oil/water systems.

Complex coacervation is an associative liquid/liquid phase separation resulting in the formation of two liquid phases: a polymer-rich coacervate phase and a dilute continuous solvent phase. In the presence of a third liquid phase in the form of disperse oil droplets, the coacervate phase tends to wet the oil/water interface. This affinity has long been known and used for the formation of core/shell capsules. However, while encapsulation by simple or complex coacervation has been used empirically for decades, there is a lack of a thorough understanding of the three-phase wetting phenomena that control the formation of encapsulated, compound droplets and the role of the viscoelasticity of the biopolymers involved. In this contribution, we review and discuss the interplay of wetting phenomena and fluid viscoelasticity in coacervate/oil/water systems from the perspective of colloid chemistry and fluid dynamics, focusing on aspects of rheology, interfacial tension measurements at the coacervate/solvent interface, and on the formation and fragmentation of three-phase compound drops. PMID:24268195

Dardelle, Gregory; Erni, Philipp

2014-04-01

442

Modeling and analysis of airlift system operating in three-phase flow

Based on the momentum theorem, the fluid governing equation in a lifting pipe is proposed by use of the method combining theoretical analysis with empirical correlations related to the previous research, and the performance of an airlift pump can be clearly characterized by the triangular relationship among the volumetric flux of air, water and solid particles, which are obtained respectively by using numerical calculation. The meso-scale river sand is used as tested particles to examine the theoretical model. Results of the model are compared with the data in three-phase flow obtained prior to the development of the present model, by an independent experimental team that used the physical conditions of the present approach. The analytical error can be controlled within 12% for predicting the volumetric flux of water and is smaller than that (±16%) of transporting solid particles in three-phase flow. The experimental results and computations are in good agreement for air-water two-phase flow within a margin of ±8%. Reasonable agreement justifies the use of the present model for engineering design purposes.

Hu, Dong; Kang, Yong; Tang, Chuan-lin; Wang, Xiao-chuan

2015-03-01

443

Unity Power Factor Operation Control Method For Single-phase to Three-phase Matrix Converter

This paper proposes a new control method of matrix converter to obtain the unity power factor operation. Source side of the matrix converter is single-phase voltage, and the load side is three-phase ac motor. The number of switching device is six, and the converter does not require a reactor or an electrolytic capacitor. Generally, it is difficult for matrix converter to control both its input current waveform and the output voltage waveform, because the switching devices are connected to both source side and load side. In this paper, applying an algebraic transfer matrix, the control method of single-phase to three-phase matrix converter applies the indirect modulation model. The indirect modulation model treats a matrix converter as a two-stage transformation converter. The rectifier of proposed model consists only diode and small L-C filter. Hence, the switching frequency is lower than the conventional model one. The inverter of the proposed model regulates both the input current waveform and the motor speed. The inverter control scheme for IPM motor is based on direct torque control (DTC). The additional current controller improves its input current waveform. Hence, an optimum switching pattern of the matrix converter realizes quick torque response and unity power factor operation. This paper describes that the proposed method achieves the power factor 97.6% by experimental tests. The experimental results confirm the feasibility of the proposed method for matrix converter.

Haga, Hitoshi; Takahashi, Isao; Ohishi, Kiyoshi

444

Design and Development of Gas-Liquid Cylindrical Cyclone Compact Separators for Three-Phase Flow

Energy Technology Data Exchange (ETDEWEB)

The objective of this five-year project (October 1997--September 2002) was to expand the current research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project was executed in two phases. Phase I (1997--2000) focused on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC) Separator. The activities of this phase included the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase II (2000--2002), the developed GLCC separator will be tested under high pressure and real crude conditions. This is crucial for validating the GLCC design for field application and facilitating easy and rapid