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1

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

2

A single leg switched PWM method for three-phase H-Bridge Voltage Source Converters

DEFF Research Database (Denmark)

This paper proposes a single leg switched or a hybrid PWM (HPWM) method for three-phase three-level H-Bridge Voltage Source Converters (3L-HB-VSCs). By means of the proposed modulation, a 3L-HB-VSC can generate the same output as a three-level neutral point clamped (3L-NPC) VSC with phase disposition (PD) PWM provided that the outputs of 3L-HBVSC are isolated by transformers or connected to open winding machines. Thus, the proposed method is called PD-HPWM. Moreover, it is emphasized that 3L-HB-VSC with HPWM utilizes its switches similar to 3L-NPC-VSC. Compared to 3L-NPC-VSCs, 3L-HB-VSCs (without neutral point clamping diodes) have simpler, more modular, and more reliable 2L circuit structure. Therefore, this method encourages the use of 3L-HB-VSCs in the applications utilizing transformers such as grid-side converters of multi-MW wind turbines. The proposed PWM method's performance is demonstrated by the simulations of a 6MW wind turbine's grid connection and experimentally verified via a smallscale prototype.

Senturk, Osman Selcuk; Helle, Lars

2009-01-01

3

In recent years, a resonant snubber to minimize switching power losses and EMI noises have attracted special interest for the voltage-fed soft switching sinewave PWM inverters and active rectifiers. The authors have discussed the performance evaluations on lower noise and high efficiency for two switch auxiliary resonant DC link snubber assisted three-phase voltage-fed soft switching PWM inverter. It was proved that cost effective three phase soft switching inverter treated here is able to improve both efficiency and EMI noise. However, some practical problems to be improved have recognized for the soft-switching three phase PWM inverter treated here from a practical point of view. This three phase soft-switching inverter with two switch type auxiliary resonant DC link snubber has significant disadvantages of DC busline link voltage reduction for the existence of the zero voltage mode transition period as well as the larger size and physical volume of electrolytic capacitor incorporated into the resonant DC link snubber. The additional technology to minimize the busline DC link zero voltage period in order to overcome the practical problems mentioned above is newly proposed in this paper. From experimental and simulation viewpoints, the modified version of this soft-switching inverter is discussed and evaluated for the DC busline voltage utilization factor as compared with the previously developed one.

Nagai, Shinichiro; Sato, Shinji; Yamamoto, Masayoshi; Hiraki, Eiji; Nakaoka, Mutsuo

4

Directory of Open Access Journals (Sweden)

Full Text Available The Three Phase Voltage Source Inverter supplies invariably required variable voltage and frequency of the adjustable speed drive system. A number of pulse width modulation (PWM schemes are used to obtain variable voltage and frequency supply from an inverter. The most widely used PWM scheme for a Three Phase Voltage Source Inverter is carrier based sinusoidal PWM and Space Vector Pulse Width Modulation (SVPWM. There is an increasing trend of using SVPWM, because of their easier digital realization and better DC bus utilization. The study of SVPWM technique reveals that this technique utilizes DC bus voltage more efficiently and generates less harmonic distortion when compared with sinusoidal PWM techniques. The SVPWM technique has become one of the important PWM technique for Three Phase Voltage Source Inverter for the control of AC induction motor, Brushless DC motor, Switched Reluctance motor and Permanent Magnet Synchronous motor. In this paper having collection of different schemes in SVPWM. Specifically various schemes are Center aligned two level SVPWM, Level shifted multi-carrier concepts based SVPWM, and Third order harmonic injection based modulated reference waveform generation and comparison in SVPWM. This paper having simulation results of all the three schemes of SVPWM by using MATLAB/SIMULINK software. The performance of Three Phase Voltage Source Inverter fed induction motor drive based on various SVPWM schemes are analyzed by various reference parameters like DC bus utilization, Total harmonic distortion (THD, switching stress and efficiency. As a result of these analysis this paper recommends which scheme is more suitable for variable voltage and various frequency drives. The simulation results are provided to validate the proposed model approaches.

S. Manivannan, S. Veerakuma

2014-01-01

5

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

6

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

7

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

8

Control Strategy for Three Phase PWM Rectifier Using SVM Modulation

Directory of Open Access Journals (Sweden)

Full Text Available This paper deals with the control of three phase PWM rectifier model using SVM based current controller. In many power electronics control applications the rectifier plays vital role during AC/DC power conversion. The SVM-based HCC scheme is simulated using MATLAB simulink. The technique combines the best features of the SVM and HCC techniques. The controller determines a set of state space vectors from a region detector and then applies a space vector selected according to HCC. A set of space vectors in a region, including the zero space vector for a reduced number of switching, is determined from the output signals of three comparators with a hysteresis band a little larger than that of the main HCC. The Simulation results prove the effectiveness of the proposed three phase PWM rectifier model.

V. Dega Rajaji

2014-06-01

9

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

10

Simulation Study of the Carrier-Based PWM Method in Three- Phase Flying Capacitor Inverters

Directory of Open Access Journals (Sweden)

Full Text Available This paper is a simulation study ofmodulation strategies in three-phase flying capacitorinverters. Under investigation are those strategies thatsolve the capacitor voltage balancing problem: phaseshiftPWM method, the saw-tooth rotation PWM methodand carrier redistribution PWM method. The results areshown through simulation.

Adrian ?chiop

2008-05-01

11

Digital Repository Infrastructure Vision for European Research (DRIVER)

* **The authors present the design, simulation and analysis of a single phase voltage source inverter using soft switching techniques. The performance of the inverter has been compared in terms of harmonic contents present in output voltage and current. The research works for a PWM inverter along with a LLCC filter has been investigated. This paper also investigated the performance of the same inverter with a feedback controller wit...*

Sunil Kumar Chaudhary; Jaffery, Z. A.

2012-01-01

12

Power Electronic Transformer based Three-Phase PWM AC Drives

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

Basu, Kaushik

13

This paper presents a novel type of 3-level 3-phase 3-switch type voltage-fed soft-switching PWM AC/DC Converter with new Active Auxiliary Resonant Commutated Snubber topology which can operate under a condition of Zero Voltage Switching. The operating performances of the proposed three phase soft-switching PWM rectifier which is more suitable for power systems applications is evaluated on the basis of Simulation results.

Yamamoto, Msayoshi; Sato, Shinji; Nakaoka, Mutsuo

14

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

15

Directory of Open Access Journals (Sweden)

Full Text Available The analysis of a carrier-based PWM two level voltage source inverter for a nine phase induction machine drive system is presented in this paper. Methods for generating zero-sequence signals during balanced and unbalanced condition are established. Simulation results for the analysis are presented. Two fault conditions involving the voltage source inverter and the nine-phase squirrel cage induction machine load are investigated. For the two fault scenarios considered, the effects on the performance characteristics of the induction machine load are highlighted. The simulation results obtained show that the two imbalance conditions considered result in substantial oscillations on the electromagnetic torque of the machine with attendant reduction in the torque rating. There is also large slip in the rotor speed.

Omonowo David Momoh

2014-07-01

16

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

17

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

18

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 inp...

Ninghui Wang; Guofeng Li; Zhongjiu Zheng

2011-01-01

19

PWM Technique for Non-Isolated Three-Phase Buck-Boost PFC Converter

The buck-boost power factor corrected (PFC) converter has the wide range of the dc output voltage. A new non-isolated three-phase hard-switching and a soft-switching buck-boost PFC converter are proposed. Removing the three-phase transformer from the converters makes their size more compact and their costs lower. In addition, the new control method based on the PWM technique is proposed in this paper to achieve the high power factor. Complete soft-switching is also achieved under the discontinuous current mode (DCM) operation.

Morizane, Toshimitsu; Shimomori, Wataru; Taniguchi, Katsunori; Kimura, Noriyuki; Ogawa, Masanori

20

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

21

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

22

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

23

Three phase six-switch PWM buck rectifier with power factor improvement

International Nuclear Information System (INIS)

Conventional Phase Controlled Rectifier injects low order current harmonics into the AC mains. Large size filtering components are required to attenuate these harmonics. In this paper, three phase six-switch PWM buck rectifier is presented which operates at nearly unity power factor and provides variable output voltage. Small size energy storing components are required depending upon switching frequency. MATLAB simulation is performed and modified Sinusoidal Pulse Width Modulation (SPWM) switching technique is used in 3kW prototype converter to demonstrate low input current THD, nearly unity displacement factor, well regulated output voltage and reduced switching losses compared to conventional SPWM.

24

Three phase six-switch PWM buck rectifier with power factor improvement

Conventional Phase Controlled Rectifier injects low order current harmonics into the AC mains. Large size filtering components are required to attenuate these harmonics. In this paper, three phase six-switch PWM buck rectifier is presented which operates at nearly unity power factor and provides variable output voltage. Small size energy storing components are required depending upon switching frequency. MATLAB simulation is performed and modified Sinusoidal Pulse Width Modulation (SPWM) switching technique is used in 3kW prototype converter to demonstrate low input current THD, nearly unity displacement factor, well regulated output voltage and reduced switching losses compared to conventional SPWM.

Zafarullah Khan, M.; Mohsin Naveed, M.; Akbar Hussain, D. M.

2013-06-01

25

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

DEFF Research Database (Denmark)

Conventional Phase Controlled Rectifier injects low order current harmonics into the AC mains. Large size filtering components are required to attenuate these harmonics. In this paper, Three Phase Six-Switch PWM Buck Rectifier[1] is presented which operates at nearly unity power factor and provides variable output voltage. Small size energy storing components are required depending upon switching frequency. MATLAB simulation is performed and modified Sinusoidal Pulse Width Modulation(SPWM) switching technique is used in 3kW prototype converter to demonstrate low input current THD, nearly unity displacement factor, well regulated output voltage and reduced switching losses compared to conventional SPWM.

Zafar Ullah Khan, M; Mohsin Naveed, M.

2013-01-01

26

Digital Repository Infrastructure Vision for European Research (DRIVER)

The equivalence of triangle-comparison-based pulse width modulation (TCPWM) and space vector based PWM (SVPWM) during linear modulation is well-known. This paper analyses triangle-comparison based PWM techniques (TCPWM) such as sine-triangle PWM (SPWM) and common-mode voltage injection PWM during overmodulation from a space vector point of view. The average voltage vector produced by TCPWM during overmodulation is studied in the stationary (a-b) reference frame. This is compared and contraste...

Modi, Manoj Kumar; Venugopal, S.; Narayanan, G.

2013-01-01

27

A Fuzzy-Logic-Based Controller for Three-Phase PWM Rectifier With Unity Power Factor Operation

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, direct power control (DPC) of three-phase PWM rectifiers based on fuzzy logic controller is presented, without line voltage sensors. The control technique is built upon the ideas of the well known direct torque control (DTC) for induction motors. 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 proposed fuzzy logic controller...

Bouafia, A.; Krim, F.

2008-01-01

28

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

29

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

30

Directory of Open Access Journals (Sweden)

Full Text Available It has been found that by using Pulse with modulation technique can greatly reduce the harmonics distortions generated by the PV inverter. Harmonics reduction is the main consideration in three phase squirrel cage induction motor. We can improve the performance of the three phase squirrel cage Induction motor by the reduction of THD. In this research work, the harmonic distortion of the three phase induction motor was measured in terms of THD by Simulation model and the results of the Multiple Pulse With Modulation and Sinusoidal Pulse With Modulation inputs were compared to discover the lowest THD value. By using the PWM technique on the Three Phase Induction motor there was reduction in the VTHD by 6.98% and CTHD by 3.12% which in turn reduces the iron, winding and stray losses occurred in three phase squirrel cage induction motor.

P.Manikandan

2014-02-01

31

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

32

Directory of Open Access Journals (Sweden)

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

C. R. Balamurugan

2012-11-01

33

A Fuzzy-Logic-Based Controller for Three-Phase PWM Rectifier With Unity Power Factor Operation

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, direct power control (DPC of three-phase PWM rectifiers based on fuzzy logic controller is presented, without line voltage sensors. The control technique is built upon the ideas of the well known direct torque control (DTC for induction motors. 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 proposed fuzzy logic controller presents the advantage to be based on linguistic description and does not require a mathematical model of the system. The controller ensures a good regulation of the output voltage, and guarantees the power factor close to one. The simulation results show that the designed fuzzy controller has a good dynamic behavior, a good rejection of impact load disturbance, and is very robust.

A. Bouafia

2008-03-01

34

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.

35

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

36

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.

37

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.

38

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

39

International Nuclear Information System (INIS)

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

40

Optimum space vector PWM algorithm for three-level inverter

Directory of Open Access Journals (Sweden)

Full Text Available A Three - Level Voltage Source Inverter is used increasingly to supply a variable frequency and variable voltage for variable speed applications. A suitable pulse width modulation (PWM technique is employed to obtain the required output voltage at the line side of the inverter. This paper studies popular multi-level topology, Diode Clamped or Neutral Point Clamped for three-level. Two methods of Sine-triangle (SPWM and two methods of Space Vector Pulse Width Modulation (SVPWM are employed to generate the modulation wave. These modulation waves are compared against a triangular carrier to generate the PWM signals for the three phases. In SVPWM methods, a revolving reference voltage vector is provided as voltage reference instead of three phase modulating waves used in SPWM. The magnitude and frequency of the fundamental component in the line side are controlled by the magnitude and frequency, respectively, of the reference vector. Space Vector Modulation Technique has become the important PWM technique for three phase Voltage Source Inverters because of its increased dc bus utilization and reduced harmonic distortion compared to SPWM. The four PWM methods are simulated in MATLAB/SIMULINK software and are compared for THD and Capacitor Balance. Programs are carried out using Embedded Editor functions and matlab editor functions. The simulation study reveals that Space vector PWM utilizes dc bus voltage more effectively, generates less THD and improved capacitor balance when compared to sine PWM.

B. Urmila

2011-09-01

41

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

42

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

43

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

44

``Dead-band`` PWM switching patterns

Energy Technology Data Exchange (ETDEWEB)

Reference/modulating waveform continuity is not a necessary condition for the implementation of switching patterns for three-phase pulse-width modulated (PWM) converters if the load or the source are Y-connected. This is based on the fact that the converter phase-voltages do not need to be sinusoidal and switching pattern discontinuities--dead-bands--do not degrade the quality of output/input voltage/current waveforms by introducing low-order harmonics if certain parameter are optimized. This paper discusses general characteristics of various discontinuous switching patterns for PWM converters and shows that they can yield better performance than their continuous counterparts in some operating regions. Performance is defined as harmonic distortion normalized with respect to effective switching frequency and serves as a measure of comparison with continuous PWM techniques. The applications considered include general purpose and application specific solid-state power supplies using voltage source inverters and PWM rectifiers. Theoretical considerations are verified on an experimental unit.

Agelidis, V.G.; Ziogas, P.D.; Joos, G. [Concordia, Univ., Montreal, Quebec (Canada). Dept. of Electrical and Computer Engineering

1996-07-01

45

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

46

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

47

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

Directory of Open Access Journals (Sweden)

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

G.NAGESWARA RAO

2010-09-01

48

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

49

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

50

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.

51

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

52

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

53

FPGA Based Three Phase Multilevel PWM Inverter

Directory of Open Access Journals (Sweden)

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

Tamboli J. I.

2014-04-01

54

Voltage Controlled Voltage Source (VCVS)

Hosted by Clarkson University, this applet demonstrates a circuit that contains a voltage controlled voltage source (VCVS). The gain may be modified using the scroll bar. Even though brief, this resource can be used in a variety of different technical education classrooms.

Dorf, Richard C.; Svoboda, James A.

2008-11-27

55

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

56

In three-phase squirrel-cage ac traction motor, temperature-rise calculation during variable-voltage and variable-frequency starting is of vital importance and has to be predicted and critically examined. Under voltage source inverter supply with PWM, the generation of harmonics by inverter supply reduces the output during starting due to higher harmonic losses, thereby reducing the starting tractive effort in kN on locomotive wheel. Stator and rotor temperature-rises during starting have been determined for average acceleration torque in segmental zone (calculated from variable acceleration) which have been presented in the paper with both copper and aluminium alloy rotor bars.

Paul, R. N.; Arya, L. D.; Verma, H. K.

2012-09-01

57

Minimization of Harmonics in PWM Inverters Based on Genetic Algorithms

Directory of Open Access Journals (Sweden)

Full Text Available This study describes a new approach based on genetic algorithm to suppress the current harmonic contents in output of an inverter. A genetic algorithm is applied to optimize a pulse width modulation (PWM inverter, which can not only spread harmonic energy but also reduce harmonic distortion. A feasible test is implemented by building a proto type three phase voltage source inverter which is designed and controlled on the basis of proposed considerations. It is verified from a practical point of view that these new approach are more effective and acceptable to minimize the harmonic distortion. Due to the complex algorithm, their realization often calls for a compromise between cost and performance.

B. Justus Rabi

2006-01-01

58

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

59

Synchronized Scheme of Continuous Space-Vector PWM with the Real-Time Control Algorithms

DEFF Research Database (Denmark)

This paper describes in details the basic peculiarities of a new method of feedforward synchronous pulsewidth modulation (PWM) of three-phase voltage source inverters for adjustable speed ac drives. It is applied to a continuous scheme of voltage space vector modulation. The method is based on a representation of the pulse patterns as a function of the fundamental and switching frequencies of the drive system. Accurate trigonometric algorithms of vector PWM have been analysed, and also compared with the algebraic ones based on linear approximation of the durations of active switching states from their position inside clock-intervals. In order to provide smooth shock-less pulse-ratio changing and quarter-wave symmetry of the voltage waveforms, special synchronising signals are formed on the boundaries of the 60 clock-intervals. The process of gradual transition from continuous to discontinuous synchronous PWM at higher values of the fundamental frequency has also been described. Results of analysis of the spectral characteristics of the output voltage of the inverter show advantage of synchronous PWM in comparison with conventional asynchronous modulation at low indices of the frequency ratio between the switching and the fundamental frequency. Special attention has been given to the analysis and comparison of the computational effectiveness of the proposed algorithms of synchronized modulation. 0

Oleschuk, V.; Blaabjerg, Frede

2004-01-01

60

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents a new hybrid three phase rectifier composed by the parallel association of a single switch three phase boost rectifier with a pwm three phase unidirectional rectifier. According to this proposal each rectifier processes about half of the output rated power. The diode rectifier operates at a low frequency and has a higher output power rating Therefore ,the pwm unidirectional rectifier is designed to operate with a small power rating and a high switching frequency. In the pr...

Ankusha Biradar,; Prof.Nagabhushan.Patil

2013-01-01

61

Voltage Source Converters with Energy Storage Capability

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

62

Synchronised PWM Schemes for Three-level Inverters with Zero Common-mode Voltage

DEFF Research Database (Denmark)

This paper presents results of analysis and comparison of novel synchronised schemes of pulsewidth modulation (PWM), applied to three-level voltage source inverters with control algorithms providing elimination of the common-mode voltage. The proposed approach is based on a new strategy of digital PWM with synchronous smooth pulses-ratio changing and a quarter-wave symmetry of the voltage waveforms. Three basic versions of both algebraic and trigonometric synchronised PWM have been analysed. Simulations give the behaviour of the proposed methods and show some advantage of synchronised PWM in comparison with asynchronous at low ratios between the switching and fundamentsl frequencies.

Oleschuk, Valentin; Blaabjerg, Frede

2002-01-01

63

Single Phase Voltage Source Inverter Photovoltaic Application

Directory of Open Access Journals (Sweden)

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

J. Bauer

2010-01-01

64

Single Phase Voltage Source Inverter Photovoltaic Application

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Bauer, J.

2010-01-01

65

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

66

Relationships between Harmonic Characteristics and Different Types of Voltage Source

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper discusses about harmonic characteristics due to different types of voltage sources. Usually, the voltage source is sinusoidal. But in actual condition the load that receive voltage sources through the elements where the output voltage of element as input to the load is not pure sinusoidal, for example voltage source at (PCC) between transformer and linear load and nonlinear load. This research has been done with Schhafner Power Quality Analyzer and PM300 Power Quality Analyzer...

2012-01-01

67

Novel multilevel inverter carrier-based PWM method

Energy Technology Data Exchange (ETDEWEB)

The advent of the transformerless multilevel inverter topology has brought forth various pulsewidth modulation (PWM) schemes as a means to control the switching of the active devices in each of the multiple voltage levels in the inverter. An analysis of how existing multilevel carrier-based PWM affects switch utilization for the different levels of a diode-clamped inverter is conducted. Two novel carrier-based multilevel PWM schemes are presented which help to optimize or balance the switch utilization in multilevel inverters. A 10-kW prototype six-level diode-clamped inverter has been built and controlled with the novel PWM strategies proposed in this paper to act as a voltage-source inverter for a motor drive.

Tolbert, L.M.; Habetler, T.G.

1999-10-01

68

Comparative Study of Multicarrier PWM Techniques for a Modular Multilevel Inverter

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the simulation of three phase five-level modular multilevel cascade inverter based on double-star chopper-cell (DSCC. The multicarrier PWM techniques such as Phase disposition PWM (PDPWM, Phase opposition disposition PWM (PODPWM, Alternate phase opposition disposition PWM (APODPWM, and Phase shift PWM (PSPWM is employed and a comparative study is done based on the spectral quality of the load voltage and load current waveforms. Simulation has been carried out for various modulation indices using MATLAB/Simulink and the results are verified.

M.S.Rajan

2014-01-01

69

Cascaded Nine Level Inverter Using Pulse Width Modulation And Hybrid PWM

Directory of Open Access Journals (Sweden)

Full Text Available The multilevel voltage source converters typically synthesize the staircase voltage wave from several levels of dc voltage sources. This paper presents a PWM modulation and hybrid modulation using cascaded topology which allows one to achieve high-quality output voltages and input currents and also outstanding availability due to their intrinsic component redundancy. The simulation results reveal that method can effectively eliminate harmonics in the output waveform of the inverter, and also low THD (Total Harmonics Distortion.

Rohini Sharma

2014-05-01

70

Development of high-voltage PWM power supply for electron beam bombarding furnace

International Nuclear Information System (INIS)

The working principle and operation characteristics of a high-voltage PWM-BUCK DC/DC converter are discussed in this paper, and a practical engineering technical route is proposed to apply the converter to high power accelerating voltage source of electron beam bombarding furnace. Compared with the traditional thyristor phase-shifted high voltage source, the application results show that the suggested power supply has the advantages of lower current harmonic, higher power factor and higher operation efficiency. (authors)

71

Indirect Vector Control of Three Phase Induction Motor using PSIM

Digital Repository Infrastructure Vision for European Research (DRIVER)

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,...

Nagulapati Kiran

2014-01-01

72

ANALYSIS OF OPERATIONAL PROPERTIES OF THREE-PHASE INDUCTION MOTOR FOR GOLF CAR DRIVE

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the diploma work the analysis of operational properties of three-phase induction motor for golf car drive is presented. The aim of the presented work is to establish such experimental system which enables analysis of induction motors in a wide range of supply-frequencies. In order to supply the tested induction machine a stationary voltage source composed of power transformers and voltage source inverter was build. On the tested induction motor, for the purpose of correct analysis, the fol...

2009-01-01

73

Optimum space vector PWM algorithm for three-level inverter

Digital Repository Infrastructure Vision for European Research (DRIVER)

A Three - Level Voltage Source Inverter is used increasingly to supply a variable frequency and variable voltage for variable speed applications. A suitable pulse width modulation (PWM) technique is employed to obtain the required output voltage at the line side of the inverter. This paper studies popular multi-level topology, Diode Clamped or Neutral Point Clamped for three-level. Two methods of Sine-triangle (SPWM) and two methods of Space Vector Pulse Width Modulation (SVPWM) are employed ...

Urmila, B.; Subba Rayudu, D.

2011-01-01

74

A Review of Passive Filters for Grid-Connected Voltage Source Converters

DEFF Research Database (Denmark)

LCL filter is the common interface between the Pulse Width Modulated Voltage Source Converter (PWM VSC) and the utility grid due to high harmonic attenuation capability and reduced size of the passive elements. The present paper investigates the most promising passive damping methods for the LCL topology but also propose an overview of high order filters capable to offer even more attenuation than the LCL filter at a reduced size. This is the case of more recently introduced LCL topology with tuned traps. However, it is shown that by decreasing the size of the passive elements the robustness of the filter also is decreased. Thus, a comparison of the filter features including the robustness towards grid impedance variation, harmonic attenuation capability and losses in the damping circuit became interesting from a practical implementation point of view. The design of the proposed filters is validated by simulation and experimental results and covers two scenarios: high and low/medium power applications.

Beres, Remus Narcis; Wang, Xiongfei

2014-01-01

75

Analysis of Input and Output Ripples of PWM AC Choppers

Directory of Open Access Journals (Sweden)

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

Pekik Argo Dahono

2008-11-01

76

Relationships between Harmonic Characteristics and Different Types of Voltage Source

Directory of Open Access Journals (Sweden)

Full Text Available This paper discusses about harmonic characteristics due to different types of voltage sources. Usually, the voltage source is sinusoidal. But in actual condition the load that receive voltage sources through the elements where the output voltage of element as input to the load is not pure sinusoidal, for example voltage source at (PCC between transformer and linear load and nonlinear load. This research has been done with Schhafner Power Quality Analyzer and PM300 Power Quality Analyzer, was focused to all harmonic characteristics as power, voltage, current, power factor (p.f., Harmonic Distortion, and harmonic energy losses cost. The load is Induction Motor with Adjustable Speed Drive (ASD because the Induction Motor with Adjustable Speed Drive (ASD is one of electronic device causes harmonics. The voltage sources in this research are sine wave, square wave and harmonic order combinations of 3rd, 5th and 7th which can create from Schhafner Power Quality Analyzer.

Yusniati Yusniati

2012-06-01

77

High performance direct instantaneous power control of PWM rectifiers

International Nuclear Information System (INIS)

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

78

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

79

Three phase downhole separator process

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

Cognata, Louis John (Baytown, TX)

2008-06-24

80

Three phase power factor controller

A power control circuit for a three phase induction motor is described. Power factors for the three phases are summed to provide a control signal, and this control signal is particularly filtered and then employed to control the duty cycle of each phase of input power to the motor.

Nola, F. J. (inventor)

1984-01-01

81

Design of New Single-phase Multilevel Voltage Source Inverter

Directory of Open Access Journals (Sweden)

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

Rasoul Shalchi Alishah

2014-07-01

82

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a three-phase line-interactive uninterruptible power supply (UPS system with active series-parallel power-line conditioning capabilities. Synchronous reference frame (SRF-based controller is used for harmonic and reactive power compensation generated from any configuration of non-linear loads. Under normal line conditions the UPS system works with universal filtering capabilities, such as compensating the input currents and output voltages. Two three-phase pulsewidth modulation (PWM converters, called series and parallel active filters, are used to perform the series and parallel active power-line compensation. The series active filter works as sinusoidal current source in phase with the input voltage, drawing from utility sinusoidal and balanced input currents with low total harmonic distortion (THD. The parallel active filter works as sinusoidal voltage source in phase with the input voltage, providing regulated and sinusoidal output voltages with low THD. The performance of the UPS system is evaluated in three-phase, four-wire systems. Experimental results are presented to confirm the theoretical studies.Este artigo apresenta um sistema de energia ininterrupta (SEI line-interactive trifásico com capacidade de condicionamento ativo de potência série e paralelo. Um controlador baseado no sistema de eixo de referência síncrona (SRF é usado na compensação de potência reativa e harmônica geradas por quaisquer configurações de cargas não lineares. Sob condições normais da rede elétrica o SEI trabalha na compensação das correntes de entrada e das tensões de saída. Dois conversores controlados em tensão e modulados por largura de pulso (PWM, chamados de filtros ativos série e paralelo, são usados para realizar o condicionamento ativo de potência série e paralelo. O filtro ativo série trabalha como uma fonte de corrente senoidal em fase com a tensão de entrada, drenando da rede correntes senoidais, balanceadas com baixas taxas de distorção harmônica (TDH. O filtro ativo paralelo trabalha como uma fonte de tensão senoidal em fase com a tensão de entrada, fornecendo para a carga tensões reguladas, senoidais e com baixas taxas de distorção harmônica. O desempenho do SEI é avaliado para sistemas trifásicos com quatro fios. Resultados experimentais são apresentados para confirmar os estudos teóricos.

Sérgio Augusto Oliveira da Silva

2005-06-01

83

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.

84

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

85

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

86

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

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a new hybrid three phase rectifier composed by the parallel association of a single switch three phase boost rectifier with a pwm three phase unidirectional rectifier. According to this proposal each rectifier processes about half of the output rated power. The diode rectifier operates at a low frequency and has a higher output power rating Therefore ,the pwm unidirectional rectifier is designed to operate with a small power rating and a high switching frequency. In the proposed scheme, dsPIC30F2010 controller is used to produce signals. A resistive load(Two incandescent lamps with different watts are used as load for testing the developed hardware. Textronics TDS2024B storage oscilloscope is used to store the gate pulses and waveforms. The perfectly sinusoidal input currents with improved power factor can be obtained by this hybrid rectifier.

Ankusha Biradar,

2013-03-01

87

A novel hybrid PWM algorithm having superior harmonic performance

Directory of Open Access Journals (Sweden)

Full Text Available 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 a-nalysis of these eight algorithms, a methodology was established for designing a hybrid modulation scheme offering superior harmonic performance. The algorithm so designed was validated theoretically by calculating the total harmonic distortion factor FDIST and experimentally by measuring the weighted total harmonic distortion factor VWTHD.

Diana Jimena López Mesa

2010-07-01

88

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

89

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

Directory of Open Access Journals (Sweden)

Full Text Available In recent years, the applications of power electronics have grown tremendously. These power electronic systems offer highly nonlinear characteristics. To overcome those non linearities active power filters are preferred. This paper presents and compares the performance of two controllers namely Fuzzy Logic and Proportional Integral (PI applied to a voltage source inverter / converter which operates as an active power filter. The active power filter is operated to compensate harmonics generated by the non-linear load . This work is done to make an accurate comparison of the performance of fuzzy logic controller and classical control technique such as PI controller in compensating harmonics in the ac mains current. Fuzzy control rule design is based on the general dynamic behavior of the process. A novel control method is implemented for suppressing the harmonics. The compensation process is instantaneous, which is achieved without employing any complicated control logic. The control scheme is based on sensing line currents only; an approach different from convention ones, which are based on sensing harmonics of the nonlinear load. In the control scheme a hysteresis controller based on current control is employed to generate switching signals to the PWM converter.

T Jagan Mohan Rao

2014-05-01

90

Energy-conservation approach to modeling PWM dc-dc converters

A new systematic method is presented for including parasitic resistances and offset voltage sources of power switches into averaged dynamic large-signal, dc, and small-signal circuit models of pulse-width modulation (PWM) converters operating in continuous conduction mode (CCM). This method is based on the principle of energy conservation. The proposed approach takes into account the inductor current ripple. With zero-ripple current simplification, the presented method gives the same results as the state-space averaging method. Reflection rules are introduced and used to simplify the models. As an example, a procedure of modeling the PWM buck converter is detailed.

Czarkowski, Dariusz; Kazimierczuk, Marian K.

1993-07-01

91

Energy Technology Data Exchange (ETDEWEB)

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

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

2001-08-01

92

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

Gheraia, H.; Berkouk, E. M.; Manesse, G.

2001-08-01

93

Stabilized voltage sources for a slow neutron diffraction analyzer

International Nuclear Information System (INIS)

An unified voltage source (UVS) and filament voltage source (FVS) are described' The sources are used for a slow neutron diffraction analyzer. FVS supplies the filament of a gun cathode and provides beam currents upto 2 mA at electric currents upto 5A and voltages upto 8V. FVS is built by a compensation scheme with continuous control. It possesses a control element with high output power and trigger protection. The range of the EVS protection circuit operation threshold control is 1-5 A, instability of output voltage doesn't exceed 1 mV, the load power consumption doesn't exceed 40 W. UVS is also built according to compensation principle with continuous control and non-regulated power supply of a negative feedback amplifier. The output voltage is controlled within the limits of 5-250 V, maximum load current is 5 mA, instability of output voltage doesn't exceed 50 mV, maximum power consumption is 1.5 W. Simplicity of the UVS circuit is reached by application of the minimum number of active and passive elements, and reliability - by the circuit protection from overloads. Operation of the slow neutron diffraction analyzer, a control unit of which is built on the base of the above voltage sources, proves their reliability and convenience. Diffraction patterns of good quality are obtained

94

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

95

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

96

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

97

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents a novel space vector selection scheme applicable for the control of dual three-phase induction motor drives supplied from a six-phase voltage source inverter (VSI). The vector selection method is based on the vector space decomposition technique (VSD). Unique vector selection pattern simplifies problems related to complicated implementation of standard VSD in commercially available digital signals processors (DSP). The proposed vector selection scheme is verified throu...

Milicevic, D.; Katic, V.; Corba, Z.; Greconici, M.

2013-01-01

98

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

99

Investigation of FPGA Based PWM Control Technique for AC Motors

Directory of Open Access Journals (Sweden)

Full Text Available This paper proposes a Random Frequency PWM synchronized for a three phase inverter implemented with use of FPGA and applied to a 1-hp induction motor drive system for the reduction of harmonics and improvement of fundamental peak voltage. For providing alternating output voltage with a specific magnitude and frequency to industrial applications, three-phase inverter is preferred. The gating signals to the inverter are produced by means of Random Frequency PWM to significantly reduce harmonics in comparison to currently used PWMs. FPGA is used to produce gating signals to the switches in a three-phase bridge inverter since a faster speed of operation is needed. The simulation is carried on VHSIC Hardware Description Language (VHDL using ModelSim. Then, this VHDL model is imported into Matlab environment and co-simulated using HDL Cosimulation toolbox. The simulation and experimental results are presented with a view to determine whether Random Frequency PWM performs better in terms of fundamental voltage and Total Harmonic Distortion.

Valantina Stephen

2013-02-01

100

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

101

Voltage harmonic variation in three-phase induction motors with different coil pitches

International Nuclear Information System (INIS)

A pulse-width modulation (PWM) inverter feeding four different chorded three-phase induction motors was tested for low-order odd harmonic voltage component and efficiency at different loads. Total harmonic distortion (THD) due to 3rd, 5th and 9th harmonics was less in a motor with 160o coil pitch. Particular harmonic order for each coil pitch was suppressed and the efficiency of a 120o coil pitch motor was increased by 7.5%

102

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

103

Mathematical analysis of PWM processes

Digital Repository Infrastructure Vision for European Research (DRIVER)

Pulse width modulation (PWM) inverters convert a direct current (DC) power supply to an alternating current (AC) supply by means of high frequency switching between two DC sources. Undesirable high-frequency components are generated in the frequency spectra of the voltages and currents of PWM inverters. The high-frequency components are ultimately removed from the input and output waveforms by filters. PWM inverters are used in a wide variety of electrical devices, ranging from microwave oven...

Ainslie-malik, Gregory R.

2013-01-01

104

Three-phase phononic materials

Directory of Open Access Journals (Sweden)

Full Text Available We consider a strongly heterogeneous material consisting of three phases: an elastic matrix, medium-size inclusions periodically embedded in the elastic matrix; these inclusions are constituted by small rigid inclusions coated by a very compliant material. The dependence on scale of elasticity coefficients of the deformable medium-size inclusions is treated in the context of linear elasticity by the homogenization procedure providing a limit model that inherently describes band gaps in acoustic wave propagation. The band gaps occur for certain intervals of long wavelengths for which a frequency-dependent "mass density" tensor is negative. We illustrate the theoretical results with numerical simulations.

Rohan E.

2009-06-01

105

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

106

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

107

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.

108

Directory of Open Access Journals (Sweden)

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

Abdulkareem Mokif Obais

2013-02-01

109

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

110

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

111

Review of multilevel voltage source inverter topologies and control schemes

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-02-15

112

Review of multilevel voltage source inverter topologies and control schemes

International Nuclear Information System (INIS)

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

113

DEFF Research Database (Denmark)

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

Mathe, Laszlo; Lungeanu, Florin

2010-01-01

114

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

115

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

International Nuclear Information System (INIS)

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

116

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

Directory of Open Access Journals (Sweden)

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

Pekik Argo Dahono

2010-05-01

117

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

Directory of Open Access Journals (Sweden)

Full Text Available Multi-phase machines and drives is a topic of growing relevance in recent years, and it presents many challenging issues that still need further research. This is the case of multi-phase space vector pulse width modulation (SVPWM, which shows not only more space vectors than the standard three-phase case, but also new subspaces where the space vectors are mapped. In the digital implementation, multiphase reference voltages are sampled and fed into the digital modulator to produce gating signals at a constant clock rate f. This means a finite pulse-width resolution because the gating state transition can only occur at some specific time instants depending on frequency. This results in a deviation of produced phase voltages from the desired phase voltages, i.e., increasing harmonic distortion especially for a small modulation index signal. In the present paper a filtered space-vector pulse-width modulation (SVPWM considering finite pulse-width resolution is proposed to produce a switching sequence with reduced baseband harmonics for multiphase voltage source inverters (VSI. This is achieved by incorporating a pseudo feedback loop regarding weighted voltage difference between desired and produced phase voltages.

K. Uday Kiran

2014-08-01

118

Directory of Open Access Journals (Sweden)

Full Text Available This work shows that the direct PWM output electric signal, with a duty cycle controlled by light intensity, can beobtained using a circuit containing a saw-tooth voltage generator connected in series with a dc voltage source and ametal (semitransparent gate oxide semiconductor capacitor (MOS-C.The internal PWM signal conversion occurs by the use of non-equilibrium physical processes in the semiconductorsubstrate of the MOS-C. The 10-20 V amplitude limited square PWM output signal is obtained by the amplification ofthe sensor signal with a standard 60 dB transimpedance amplifier. The amplified output signal presents positive andnegative PWM waveforms that can be easily separated using diodes. The duty of the positive part is proportional tothe light intensity, whereas the negative part is inversely proportional to the intensity. The frequency operating rangeof this proposed instrument varies from 1 Hz to a few kilohertz. The duty cycle of the PWM output signal varies from2% to 98% when the incident light intensity varies in the microwatts range. These new transducers or sensors couldbe useful for automatic control, robotic applications, dimmer systems, feedback electronic systems, and non-contactoptical position sensing for nulling and centering measurements.

F. J. De la Hidalga-W

2013-01-01

119

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: English Abstract in spanish Este trabajo presenta dos técnicas de control de corriente para convertidores trifásicos de voltaje trabajando como rectificadores controlados, operando con factor de potencia unitario. El primer algoritmo está basado en la escogencia del mejor vector natural, entre los 7 vectores espaciales natural [...] es del convertidor de dos niveles de voltaje trifásico, mediante una función de costo. El segundo está basado en el cómputo y síntesis del vector espacial óptimo de convertidores trifásicos tal que se obtiene el vector que proporciona un mínimo absoluto de la función de costo. El primer algoritmo es un método sencillo que controla muy bien el factor de potencia y presenta una considerable compensación del contenido armónico. El segundo algoritmo provee una nueva fórmula cerrada para calcular el vector de voltaje óptimo aplicado al convertidor. Para este segundo método se necesita generar la señal de control con un modulador de ancho de pulso para así controlar directamente la corriente de línea permitiendo seguir la referencia de corriente. Las simulaciones y resultados experimentales muestran las ventajas del algoritmo propuesto. Abstract in english This work presents two current loop techniques, for three phase voltage source converters (VSC) used as controlled rectifiers (CR) operating at unity power factor. The first one is based on choosing the best natural vector, among the natural space vectors produced by two level voltage source inverte [...] rs, with the use of a cost function. The second one is based on computing and synthesizing a space vector such that an absolute minimum in the cost function is obtained. The first algorithm is a simple method that presents power factor correction and good total harmonic distortion compensation. The second algorithm provides a novel and closed form formula to calculate the optimum voltage vector applied by the converter. In this method, pulse width modulation (PWM) is required to modulate the voltage vector that controls directly the line current, to follow the current reference. The simulations and experimental results show the advantages of the proposed control algorithm.

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

120

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: English Abstract in spanish Este trabajo presenta dos técnicas de control de corriente para convertidores trifásicos de voltaje trabajando como rectificadores controlados, operando con factor de potencia unitario. El primer algoritmo está basado en la escogencia del mejor vector natural, entre los 7 vectores espaciales natural [...] es del convertidor de dos niveles de voltaje trifásico, mediante una función de costo. El segundo está basado en el cómputo y síntesis del vector espacial óptimo de convertidores trifásicos tal que se obtiene el vector que proporciona un mínimo absoluto de la función de costo. El primer algoritmo es un método sencillo que controla muy bien el factor de potencia y presenta una considerable compensación del contenido armónico. El segundo algoritmo provee una nueva fórmula cerrada para calcular el vector de voltaje óptimo aplicado al convertidor. Para este segundo método se necesita generar la señal de control con un modulador de ancho de pulso para así controlar directamente la corriente de línea permitiendo seguir la referencia de corriente. Las simulaciones y resultados experimentales muestran las ventajas del algoritmo propuesto. Abstract in english This work presents two current loop techniques, for three phase voltage source converters (VSC) used as controlled rectifiers (CR) operating at unity power factor. The first one is based on choosing the best natural vector, among the natural space vectors produced by two level voltage source inverte [...] rs, with the use of a cost function. The second one is based on computing and synthesizing a space vector such that an absolute minimum in the cost function is obtained. The first algorithm is a simple method that presents power factor correction and good total harmonic distortion compensation. The second algorithm provides a novel and closed form formula to calculate the optimum voltage vector applied by the converter. In this method, pulse width modulation (PWM) is required to modulate the voltage vector that controls directly the line current, to follow the current reference. The simulations and experimental results show the advantages of the proposed control algorithm.

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

2012-09-01

121

Directory of Open Access Journals (Sweden)

Full Text Available The space vector pulse width modulation (SV-PWM is more suitable and can increase the obtainable DC voltage utilization ratio very much compared to others PWM. Moreover, the modulation can obtain a better voltage total harmonic distortion (THD factor. But until now, no studies that concern at hardware resources saving to realize SV-PWM based on FPGA. This paper proposes a new technique to realize SV-PWM based on FPGA. In order to get hardware resource saving, a simple technique to judge sectors, to calculate the firing pulses and to generate SV-PWM waveform without calculation of trigonometric function using bus-clamping technique is proposed. The technique has been implemented successfully based on APEX20KE FPGA to drive three phase induction machine 1.5 kW with low ripples in current and voltage, and has been shown that the proposed SVM method required the most minimum hardware resources compared to others research.

Tole Sutikno

2009-12-01

122

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

Scientific Electronic Library Online (English)

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

123

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

124

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

Scientific Electronic Library Online (English)

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

125

IGBT Fuses for Protection Against Explosion in Voltage Source Converters

DEFF Research Database (Denmark)

The consequences of electrical faults can be severe; not only to the equipment, but also in the worse case, to people if safety principles are not observed. Every year new applications based on DC-link Voltage Source Converters are added and the demand for protection of power electronics increases regarding the high-power IGBT modules. Due to the fact that the power level increases more energy is stored in the DC-link and even with an active protection, a high-power IGBT still has a risk of case rupture (explode) when a circuit failure condition occurs. A possible solution is a protection of the converter with standard High Speed Fuses or High Speed IGBT fuses. It is discussed that protection can be achieved by introduction of IGBT fuse located in the DC-link. Experiments show that explosion can be avoided by use of High Speed Fuse protection and the added inductance of standard High Speed- and IGBT Fuses in the DC-link is investigated. The current distribution in fuses is discussed when high frequency components are present in the load current. Further it is discussed how the extra cost for IGBT fuses may be balanced by ease of maintenance and less downtime of manufacturing equipment.

Blaabjerg, Frede; Iov, Florin

2004-01-01

126

Component-Minimized Buck-Boost Voltage Source Inverters

DEFF Research Database (Denmark)

This paper presents the design of buck-boost B4 inverters that can be derived from either ?uk- or SEPIC-derived buck-boost B6 inverters. Unlike traditional inverters, the integration of front-end voltage boost circuitry and inverter circuitry allows it to perform buck-boost voltage inversion. In order to form a distinct neutral potential in the corresponding voltage boost circuitry for correct B4 inverter operation, necessary modifications are derived step by step. The resulted dc networks with symmetrical placement of passive components allow complete charging and equal energy distribution between capacitors. Modulation wise, the proposed buck-boost B4 inverters can be controlled using a carefully designed carrier-based pulse-width modulation (PWM) scheme that will always ensure balanced threephase outputs as desired, while simultaneously achieving minimal voltage stress across semiconductors. Besides the advantage of reduced active components, buck-boost B4 inverters use a little more passive components when compared with buck-boost B6 inverters, which would allow a selectable tradeoff in practice. Moreover, analysis for discontinuous conduction mode of inductor current reveals the additional voltage relationship between dc input and ac output which is beyond the expectation when continuous inductor current is assumed. These theoretical findings, together with the inverter practicality, have been confirmed in Matlab/PLECS simulations and experimentally using laboratory implemented inverter prototypes.

Gao, F.; Loh, P.C.

2007-01-01

127

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

128

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.

129

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

130

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

131

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

132

Three-Phase Power Factor Controller

Three-Phase Power-Factor Controller develops a control signal for each motor winding. As motor loading decreases, rms value of applied voltage is decreased by feedback-control circuit. Power consumption is therefore lower than in unregulated operation. Controller employs phase detector for each of three phases of delta-connected induction motor. Phase-difference sum is basis for control.

Nola, F. J.

1982-01-01

133

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

134

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

135

DEFF Research Database (Denmark)

Pulse width modulation (PWM) is a key element of a voltage source inverter, inverter which is widely used for electric motor control and electric energy conversion. Several PWM methods have been proposed in the literature, focusing on performance, ease of implementation, and maximization of the transfer ratio. The difference between most of the proposed modulation methods like sine-triangular, SVM, and 120 - 60 - 30 Discontinuous PWM consists in the redistribution of the time-length applied for the zero voltage vectors during a fundamental frequency period. This paper presents a unified analytical equation for determining the theoretical spectra components for all the carrier based PWM methods with redistributed zero space vector time-length using the double Fourier integral analysis. The proposed unified equation can also be used for determination of the phase and line-to-line voltage spectra when the modulator works in over-modulation region. Moreover, the effect of the DC-link voltage ripple on the line-to-line voltage spectra is also considered. The experimental results show a very good agreement with the theoretically calculated spectra.

Mathe, Laszlo; Cornean, Horia

2011-01-01

136

Scientific Electronic Library Online (English)

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

137

We have performed comparative studies of Space Vector Pulse Width Modulation (SVPWM) and Sinusoidal Pulse Width Modulation (SPWM) techniques utilizing MATLAB tools. During these investigations, we carried out intensive simulations, comprehensively analyzed the obtained results and compared the harmonic density, power factor (PF), & switching losses of SVPWM and SPWM. It has been observed during investigations that if the switching frequency is high then losses due to harmonics are negligible, thus based on obtained results we suggested that the SVPWM technique is a more reliable solution. Because SVPWM utilizes DC bus voltage more efficiently, generates less Total Harmonic Distortion (THD) and has higher output quality it provides flexible control of output voltage and output frequency for Variable Speed Drive (VSD).

Ahmed, Waheed; Usman Ali, Syed M.

2013-12-01

138

Space Vector Pulse Width Modulation Schemes for Two-Level Voltage Source Inverter

Digital Repository Infrastructure Vision for European Research (DRIVER)

Space Vector Pulse Width Modulation (SVPWM) method is an advanced, computation intensive PWM method and possibly the best among all the PWM techniques for variable frequency drive applications. The SVPWM is an alternative method for the determination of switching pulse width and their position. The major advantage of SVPWM stem from the fact that, there is a degree of freedom of space vector placement in a switching cycle. This feature improves the harmonic performance of this method. This me...

Tripura, P.; Kishore Babu, Y. S.; Tagore, Y. R.

2011-01-01

139

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 a...

Nu?n?ez–gutie?rrez, C.; Lira–pe?rez, J.; Ca?rdenas–galindo, V. M.; Alvarez–salas, R.

2009-01-01

140

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)

141

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

142

Scientific Electronic Library Online (English)

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

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

143

Scientific Electronic Library Online (English)

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

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

2013-02-01

144

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

145

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

146

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

147

DEFF Research Database (Denmark)

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

Oleschuk, V.; Blaabjerg, Frede

2002-01-01

148

Three-Phased Wake Vortex Decay

A detailed parametric study is conducted that examines vortex decay within turbulent and stratified atmospheres. The study uses a large eddy simulation model to simulate the out-of-ground effect behavior of wake vortices due to their interaction with atmospheric turbulence and thermal stratification. This paper presents results from a parametric investigation and suggests improvements for existing fast-time wake prediction models. This paper also describes a three-phased decay for wake vortices. The third phase is characterized by a relatively slow rate of circulation decay, and is associated with the ringvortex stage that occurs following vortex linking. The three-phased decay is most prevalent for wakes imbedded within environments having low-turbulence and near-neutral stratification.

Proctor, Fred H.; Ahmad, Nashat N.; Switzer, George S.; LimonDuparcmeur, Fanny M.

2010-01-01

149

Expansion of three-phase fluidized bed

Energy Technology Data Exchange (ETDEWEB)

This article reports on experimental studies of the expansion of a three-phase fluidized bed, used in hydroprocessing heavy petroleum residual stocks, in relation to the catalyst bed height and the linear velocities of liquid and gas. The height of the settled bed of catalyst was varied from 200 to 1000 mm. The rising gas-liquid flow fluidizes and expands the catalyst bed. The height of the three-phase fluidized bed in the column with transparent walls was determined visually by passing a light beam through the column. It is determined that the dependence of the height of the spray zone on the gas velocity is due to the fact that the gas flow emerges from the upper level of the fluidized bed in the form of a jet, capturing solid-phase particles and ejecting them from the bed with an energy that is proportional to the linear velocity of the gas.

Razumov, I.M.; Dukel' skii, G.Y.; Kurganov, V.M.; Rossina, M.R.; Terekhov, N.I.

1984-01-01

150

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

151

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

152

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

153

Digital Repository Infrastructure Vision for European Research (DRIVER)

This report is the result of a Master Thesis work done at Seaward Electronics Inc. in Beijing, China from June to December in 2007. The main goal for this thesis is to verify and improve the performance of Honey-PWM DC-DC converter, which has been fabricated by a standard 0.6um CMOS processes. The project was started with studying of Buck converter structure. After the understanding of the converter structure, the project goes in to the analyses phase for each sub-cells, including the theory,...

Chen, Juan

2008-01-01

154

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

155

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

Directory of Open Access Journals (Sweden)

Full Text Available This work proposes three phase five level Bridge module type Diode Clamped Multilevel Inverter (DCMLI using various modulating techniques for induction motor load. These Pulse Width Modulating (PWM techniques include Carrier Overlapping (CO strategy, Variable Frequency (VF strategy, Phase Shift (PS strategy and Sub-Harmonic Pulse Width Modulation (SHPWM i.e. Phase Disposition (PD strategy, Phase Opposition Disposition (POD strategy and Alternate Phase Opposition Disposition (APOD strategy. The Total Harmonic Distortion (THD, VRMS (fundamental, crest factor, form factor and distortion factor are evaluated for various modulation indices. Simulation is performed using MATLAB-SIMULINK. It is observed thatPODPWM/PSPWM methods provide output with relatively low distortion for R Load. It is also observed that PSPWM method provides output with relatively low distortion for IM load. COPWM is also found to perform better since it provides relatively higher fundamental RMS output voltage for Induction Motor (IM load and R load.

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

2012-06-01

156

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

157

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english This paperwork presents a Pulse Width Modulation (PWM) speed controller for an electric mini-baja-type car. A battery-fed 1-kW three-phase induction motor provides the electric vehicle traction. The open-loop speed control is implemented with an equal voltage/frequency ratio, in order to maintain a [...] constant amount of torque on all velocities. The PWM is implemented by a low-cost 8-bit microcontroller provided with optimized ROM charts for distinct speed value implementations, synchronized transition between different charts and reduced odd harmonics generation. This technique was implemented using a single passenger mini-baja vehicle, and the essays have shown that its application resulted on reduced current consumption, besides eliminating mechanical parts.

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

2007-03-01

158

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

159

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english This paperwork presents a Pulse Width Modulation (PWM) speed controller for an electric mini-baja-type car. A battery-fed 1-kW three-phase induction motor provides the electric vehicle traction. The open-loop speed control is implemented with an equal voltage/frequency ratio, in order to maintain a [...] constant amount of torque on all velocities. The PWM is implemented by a low-cost 8-bit microcontroller provided with optimized ROM charts for distinct speed value implementations, synchronized transition between different charts and reduced odd harmonics generation. This technique was implemented using a single passenger mini-baja vehicle, and the essays have shown that its application resulted on reduced current consumption, besides eliminating mechanical parts.

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

160

Shootthrough fault protection system for bipolar transistors in a voltage source transistor inverter

International Nuclear Information System (INIS)

Faulted bipolar transistors in a voltage source transistor inverter are protected against shootthrough fault current, from the filter capacitor of the d-c voltage source which drives the inverter over the d-c bus, by interposing a small choke in series with the filter capacitor to limit the rate of rise of that fault current while at the same time causing the d-c bus voltage to instantly drop to essentially zero volts at the beginning of a shootthrough fault. In this way, the load lines of the faulted transistors are effectively shaped so that they do not enter the second breakdown area, thereby preventing second breakdown destruction of the transistors

161

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Full Text Available Voltage Source Converter (VSC based HVDC transmission technology hasbeen selected as the basis for several recent projects due to its controllability,compact modular design, ease of system interface, and low environmentalimpact. This paper investigates the dynamic performance of a 200MW,±100kV VSC-HVDC transmission system under some faulted conditionsusing MATLAB/Simulink. Simulation results confirm the satisfactoryperformance of the proposed system under active and reactive powervariations and fault conditions.

Amiri RABIE

2009-12-01

162

The Initial Parameters Design of the Voltage Source Converter Fed SMES

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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

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

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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

A Resonant Integrator Based PLL and AC Current Controller for Single Phase Grid Connected PWM-VSI

Digital Repository Infrastructure Vision for European Research (DRIVER)

Grid connected PWM-VSIs are being increasingly used for applications such as Distributed Generation (DG), power quality, UPS etc. Appropriate control strategies for grid synchronisation and line current regulation are required to establish such a grid interconnection and power transfer. Control of three phase VSIs is widely reported in iterature. Conventionally, dq control in Synchronous Reference Frame(SRF) is employed for both PLL and line current control where PI-controllers are used to tr...

Venkatramanan, D.; John, Vinod

2010-01-01

166

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.

Mohamadou, Youssoufa; In Oh, Tong; Wi, Hun; Sohal, Harsh; Farooq, Adnan; Woo, Eung Je; McEwan, Alistair Lee

2012-10-01

167

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

168

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

169

Scientific Electronic Library Online (English)

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

170

Directory of Open Access Journals (Sweden)

Full Text Available A UPS inverter operates in wide load impedance ranges from resistive to capacitive or inductive load. At the same time, fast transient load response, good load regulation and good switching frequency suppression is required. The variation of the load impedance changes the filter transfer characteristic and thus the output voltage value. In this paper, an analysis and simulation of the single phase voltage source uninterruptible power supply (UPS with fourth order filter (multiple-filter in output inverter, based on the state space averaging and small signal linearization technique, is proposed. The simulation results show the high quality sinusoidal output voltage at different loads, with THD less than %5.

Javad Faiz

2011-01-01

171

Energy Technology Data Exchange (ETDEWEB)

This paper describes a line-interactive single-phase to three-phase converter. The typical application is in rural areas supplied by the single-wire with earth return. The traditional objective of feeding a three-phase induction motor is not anymore the main concern for such conversion. Due to the evolution of the agro business, some of the local load (as electronic power converters, computers, communication equipment, etc.) requires high quality power, intended as sinusoidal, symmetrical and balanced three-phase voltage. Additionally, to maximize the power got from the feeder, the system provides a unitary power factor to the feeder. A three-phase PWM converter is used for this purpose. The power converter does not process all the load power, as in the conventional solutions, but only the fraction necessary to regulate the three-phase bus voltage. The control strategy, design highlights and experimental results are presented. (author)

Machado, Ricardo Q.; Pomilio, Jose A. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Eletrica e de Computacao], e-mail: ricardom@dsce.fee.unicamp.br; Buso, Simone [Universidade de Padova, Padua (Italy). Dept. de Engenharia da Informacao], e-mail: simone.buso@dei.unipd.it

2004-07-01

172

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

173

Energy Technology Data Exchange (ETDEWEB)

A PWM method has been applied to a high capacity six phase current source inverter system in order to obtain sinusoidal output voltage and current. In this system, the three-phase coupling reactor is connected between the inverter output and an induction motor used as a load. Then the reactor eliminates harmonic components included in the inverter output current except 12k {+-} 1 (k=1,2,3)th order. As a result, the distortion factor of the inverter output current decreases. But the resonant circuit is composed of the capacitance of filter capacitor and the induction motor leakage inductance. Then the resonance current is superimposed on the induction motor phase currents. To solve this problem, the optimal PWM pattern is derived, so that the resonant current becomes very small. The order of the resonant frequency component of the induction motor phase current depend on the inverter frequency. Then total inverter frequency range is divided into several areas. The optimal PWM pattern is derived in each areas. As a result, the use of each optimal PWM pattern allows us to drive the induction motor, over a wide range of speed, under the condition of small distortion factor of phase currents. 5 refs., 10 figs., 1 tab.

Inami, K.; Danjo, M.; Kondo, Y.; Yamada, M. [Niihama Technical College, Ehime (Japan); Toki, K. [Shikoku Electric Power Co., Inc., Kagawa (Japan); Heike, J. [Shikoku Instrumentation Co. Ltd., Kagawa (Japan)

1998-10-01

174

Digital Computer Transient Models of Three-Phase Inverter Systems Under Normal and Fault Conditions

In many industrial applications, variable speed drives of electrical machines are needed. This speed control can be met either by dc or ac machines. The ac machines have several distinct advantages compared to dc machines due to the absence of commutators, therefore, a variable -voltage, variable-frequency power supply is normally required for speed control of ac machines. This power supply can be obtained by a dc link converter system that consists of a rectifier and inverter. In this dissertation the waveforms and transient response of a three-phase forced-commutated inverters are simulated on a digital computer from basic circuit theory. Both the voltage source inverter (VSI) and the current source inverter (CSI) are simulated using thyristors with real characteristics. The simulation is further modified to give three-phase currents with adjustable frequency to be used in adjustable speed induction motor drives or the starting of synchronous motors from rest. The digital simulation of Gate Turn-Off (GTO) thyristor inverters feeding an induction motor is presented and can allow for step frequency change for the study of adjustable speed induction motor drives. A naturally-commutated three-phase inverter using thyristors with real characteristics was also simulated to study VSIs and CSIs. The interactions between the load parameters and the inverter circuit parameters are investigated. The parameters studied include ratio of dc voltage to amplitude of ac voltage, ratio of smoothing inductance to load inductance and triggering angle (alpha). Since the naturally-commutated CSI system is widely used in power applications, it was investigated under different types of fault s occurring both on the line and in the inverter circuit. These faults include three-phase short circuits, thyristor failures, line-to-line faults, false triggering and open circuits. A digital computer was used to simulate these faults and the system response because it is difficult to obtain the information herein for abnormal operations by any other method. This study clearly demonstrates that the theoretical circuit so simulated for different types of faults will allow designers of systems to predict accurately values of, short-circuit current ratios, maximum fault clearing times, limiting values of commutating capacitors and transient recovery voltage excursions. (Abstract shortened with permission of author.).

Gawish, Said Abdelhamid Atiya

175

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

In the paper, a vibration damping system powered by harvested energy with implementation of the so-called SSDV (synchronized switch damping on voltage source) technique is designed and investigated. In the semi-passive approach, the piezoelectric element is intermittently switched from open-circuit to specific impedance synchronously with the structural vibration. Due to this switching procedure, a phase difference appears between the strain induced by vibration and the resulting voltage, thus creating energy dissipation. By supplying the energy collected from the piezoelectric materials to the switching circuit, a new low-power device using the SSDV technique is proposed. Compared with the original self-powered SSDI (synchronized switch damping on inductor), such a device can significantly improve its performance of vibration control. Its effectiveness in the single-mode resonant damping of a composite beam is validated by the experimental results.

Shen, Hui; Ji, Hongli; Zhu, Kongjun; Balsi, Marco; Giorgio, Ivan; dell'Isola, Francesco

2010-01-01

176

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

177

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

178

Voltage source ac-to-dc converters for high-power transmitters

This work was done to optimize the design of the components used for the beam power supply, which is a component of the transmitters in the Deep Space Network (DSN). The major findings are: (1) the difference in regulation between a six-pulse and a twelve-pulse converter is at most 7 percent worse for the twelve-pulse converter; (2) the commutation overlap angle of a current source converter equals that of a voltage source converter with continuous line currents; (3) the sources of uncharacteristic harmonics are identified with SPICE simulation; (4) the use of an imperfect phase-shifting transformer for the twelve-pulse converter generates a harmonic at six times the line frequency; and (5) the assumptions usually made in analyzing converters can be relaxed with SPICE simulation. The results demonstrate the suitability of using SPICE simulation to obtain detailed performance predictions of ac-to-dc converters.

Cormier, R.

1990-01-01

179

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

DEFF Research Database (Denmark)

Precise knowledge of the plant time constant is essential to perform a thorough analysis of the current control loop in voltage source converters (VSCs). As the loop behavior can be significantly influenced by the VSC working conditions, the effects associated to converter losses should be included in the model, through an equivalent series resistance. In a recent work, an algorithm to identify this parameter was developed, considering the inductance value as known and practically constant. Nevertheless, the plant inductance can also present important uncertainties with respect to the inductance of the VSC interface filter measured at rated conditions. This paper extends that method so that both parameters of the plant time constant (resistance and inductance) are estimated. Such enhancement is achieved through the evaluation of the closed-loop transient responses of both axes of the synchronous reference frame when a proportional integral current controller is implemented. Experimental results validate the approach.

Vidal, Ana; Yepes, Alejandro G.

2014-01-01

180

Discrete/PWM Ballast-Resistor Controller

Circuit offers low switching loss and automatic compensation for failure of ballast resistor. Discrete/PWM ballast-resistor controller improved shunt voltage-regulator circuit designed to supply power from high-resistance source to low-impedance bus. Provides both coarse discrete voltage levels (by switching of ballast resistors) and continuous fine control of voltage via pulse-width modulation.

King, Roger J.

1994-01-01

181

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

182

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

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 This paper presents a performance study of the proportionalintegral controller andthe fuzzy logic controller in scalar speed control of three phase squirrel cage induction motor drive. Here the speed control is possible by varying supply frequencyusing a voltage source inverter while keeping voltage to frequency ratio as a constant. Speed error is given as inputto the proportional integral controller, and speed error and change in speed error are given as input to the fuzzy logic controller.The controller output controls the reference of sinusoidal pulse width modulation. Hence, the fundamental frequency and fundamental voltage of inverter output can be varied to control the motor speed.The performance of proportional integral controller and fuzzy logic controller underload torqueand reference speed variationisevaluated by simulation results in Simulink.

SAFDAR FASAL T K, UNNIKRISHNAN L

2013-07-01

185

A New Topology of Three-Phase Four-Wire UPQC with a Simplified Control Algorithm

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, a simplified control algorithm based on unit vector template generation (UVTG is proposed for a star-delta supported three-phase four-wire (3P-4W unified power quality conditioner (UPQC topology for the improvement of different power quality problems. Different topologies reported in literature for 3P-4W UPQC use active compensation for the mitigation of source neutral current along with other power quality (PQ problems, while the uses of passive elements for the mitigation of source neutral current are advantageous over the active compensation due to ruggedness and less complexity of control. Hence, in this paper a star-delta transformer is connected in shunt near the load for mitigation of source neutral current, while three-leg voltage source inverters (VSIs based shunt and series active power filters (APFs of 3P-4W UPQC mitigate the current and voltage based distortions, respectively. A simple control algorithm based on Unit Vector Template Generation (UVTG is used as a control strategy of UPQC for mitigation of different PQ problems. In this control scheme, the current/voltage control is applied over the fundamental supply currents/load voltages instead of fast changing APFs currents/voltages, thereby reducing the effects of computational delay and the required sensors. The performance of the proposed topology of UPQC is analyzed through simulations results using MATLAB software with its Simulink and Power System Block set toolboxes.

Yash Pal

2012-03-01

186

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

187

Energy Technology Data Exchange (ETDEWEB)

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. (author)

Pires, Dulce F. [Escola Sup. Tecnologia Setubal/Inst. Politecnico Setubal, Setubal (Portugal); Pires, V. Fernao [Escola Sup. Tecnologia Setubal/Inst. Politecnico Setubal, Setubal (Portugal)]|[LabSEI - Laboratorio de Sistemas Electricos Industriais, Setubal (Portugal); Martins, J.F. [CTS, Faculdade de Ciencias e Tecnologia/UNL, Lisboa (Portugal); Pires, A.J. [Escola Sup. Tecnologia Setubal/Inst. Politecnico Setubal, Setubal (Portugal)]|[LabSEI - Laboratorio de Sistemas Electricos Industriais, Setubal (Portugal)]|[CTS, Faculdade de Ciencias e Tecnologia/UNL, Lisboa (Portugal)

2009-04-15

188

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

189

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

190

International Nuclear Information System (INIS)

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

191

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.

192

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

193

Improvement of electromagnetic compatibility of motor drives using chaotic PWM

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, a new chaotic pulse width modulation (PWM) scheme is proposed and implemented to reduce the conducted electro-magnetic interference (EMI) in motor drives. The key is the use of logistic mapping to chaoize a frequency-modulated signal which then modulates the carrier frequency. Compared with the sinusoidal PWM and random PWM, the proposed scheme not only suppresses the peaky EMI, but also avoids the occurrence of low-order noises and mechanical resonance. Both simulation and exp...

Chau, Kt; Wang, Z.; Liu, C.

2007-01-01

194

HIGH ??? CURRENT PWM BIPOLAR STEPPER MOTOR CONTROL AND DRIVE

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper presents some investigations and research results concerning the general purpose PWM (pulse-width modulation) with applications to stepper motor control and drive. In order to improve the dynamic performances of the motor, a PWM inverter has been realised using dedicateded ICs. The bridges are capable of sustaining 46V and include internal pulse-widht modulation(PWM) control of the output curent to 2A. The laboratory prototype of the implemented digital control system, and experimen...

Morar, Alexandru

2011-01-01

195

The Teaching of Three-Phase Alternating Current

Describes a series of experiments which use a modified automobile alternator as a portable source of three-phase alternating current. The low frequency capabilities of this source allow the phase relationships to be demonstrated using an ordinary galvanometer. (GS)

Bunker, C. A.

1976-01-01

196

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

197

Reducing three-phase power imbalance with electric springs

Digital Repository Infrastructure Vision for European Research (DRIVER)

Electric springs have been used previously in stabilizing mains voltage fluctuations in power grid fed by intermittent renewable energy sources. This paper describes a new three-phase electric spring circuit and its new operation in reducing power imbalance in the three-phase power system of a building. Based on government energy use data for tall buildings, the electric loads are classified as critical and non-critical loads so that tall building energy model can be developed. The proposed e...

Yan, S.; Tan, Sc; Lee, Ck; Hui, Rsy

2014-01-01

198

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

199

Research on coordinate transformation of the three-phase circuit

Directory of Open Access Journals (Sweden)

Full Text Available 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, the three often used expressions of coordinate transformation matrixes rotating at arbitrary speed are obtained through selecting these different parameters, which are Park transformation, orthogonal transformation and the coordinate transformation in the theory of instantaneous power. The paper further points out that, through particularly choosing coordinate rotation speed ,it can get commonly used special coordinate transformation matrixes between the three-phase stationary coordinate systems, and between the stationary coordinate system and synchronous rotating coordinate system by matrix general expression. The work of this paper shows that the three-phase circuit coordinate transformation matrixes are essentially uniformed, though their forms and practical applications are different, which is helpful to further understanding and correctly using the coordinate transformation theory of three-phase circuit.

Tian Ming Xing

2013-08-01

200

Three-phase relative permeability of Asphalt Ridge tar sand

Energy Technology Data Exchange (ETDEWEB)

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

Sullivan, S.; Vaughn, P.

1988-08-01

201

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

202

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

203

Three-Phase Electronic Ballast With Current-Equalization Function

This paper proposes a three-phase electronic ballast with current-equalization function. By properly designing the resonant tank and the values of the resonant inductance and resonant capacitance, the current difference between lamps can be significantly reduced. Hence, current-equalization can be achieved by means of impedance-matching. Without an additional current-equalization circuit, the cost of the proposed circuit is reduced due to fewer components. The analysis and design of the proposed circuit will be presented in this paper. Finally, the proposed three-phase electronic ballast with current-equalization function will be implemented to validate and demonstrate the performance and feasibility of the proposed circuit.

Lin, Ray-Lee; Wen, Chien-Hsin

2006-12-01

204

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

205

A high-quality multi-level voltage source inverter suitable for high power/high voltage applications

International Nuclear Information System (INIS)

In this paper new magnitudes for D C side capacitors' voltages of a multi level voltage source inv enter are presented. Using these magnitudes of D C side capacitors voltage allow generation of ?3k steps of A C output voltage by cascade connection of only N single-phase full bridge inverter. This subject has resulted in almost sinusoidal output voltage wave form. Approximated equal area pulse amplitude modulation technique is used to calculate the duration of each step of voltage, which has resulted in reduction of complexity of control circuit. A simple closed-loop controller is developed for controlling the voltage of D C side capacitors. Harmonic analysis and capacitor calculations are presented, too. Simulation results have been used to verify the overall operation of the proposed multi level voltage source inverter in feeding a R-L load with a stepped sinusoidal wave form

206

Reactive power compensation and harmonic reduction are two relevant research problems that exist in modern electric power systems. With the advancement of modern power electronics technology in both circuits and devices, new and better solutions are being proposed and applied to solve these two problems. To compensate reactive power, a cascading voltage source inverter with a Phase-Shift, Unipolar SPWM switching scheme is proposed. The main circuit of this inverter is composed of several identical voltage source H-bridge inverters connected in cascade form. Advantages of this scheme include use of identically rated storage capacitors, similarly rated switches and diodes, quick system response to load changes, and easily achievable redundancy. To solve the harmonic reduction problem, the flying capacitor multilevel voltage source inverter is adopted to construct a novel power line conditioner. The Phase Shift SPWM switching scheme is also employed to operate the switches of this inverter. As a result, it is possible to extend the new power line conditioner to distribution systems or industrial applications where voltage usually ranges from 4.16kV to 13.8kV. It is shown that the proposed power line conditioner not only balances the unbalanced load, but simultaneously compensates the reactive power as well.

Liang, Yiqiao

207

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

208

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

209

Single-Chip Microcomputer Control Of The PWM Inverter

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

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

1987-10-01

210

HIGH ??? CURRENT PWM BIPOLAR STEPPER MOTOR CONTROL AND DRIVE

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents some investigations and research results concerning the general purpose PWM (pulse-width modulation with applications to stepper motor control and drive. In order to improve the dynamic performances of the motor, a PWM inverter has been realised using dedicateded ICs. The bridges are capable of sustaining 46V and include internal pulse-widht modulation(PWM control of the output curent to 2A. The laboratory prototype of the implemented digital control system, and experimentally results are also presented in the paper.

Alexandru MORAR

2011-11-01

211

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

212

Modelling of a three-phase concentric HTS-cable

International Nuclear Information System (INIS)

We have considered a three-phase concentric high-Tc superconducting (HTS)-cable with a copper shield neutral wire in a three-phase system. An equivalent circuit model describing the cable by the global quantities current and voltage has been developed, by which the effects of design parameters such as material, layer radii and pitch length can be investigated. The equivalent circuit consists of a nonlinear resistance, a hysteretic inductance (to model HTS), and an inductance (to model mutual inductances). The equivalent circuit is here extended with a by-pass resistance that models the silver matrix of the HTS tape. This enables to consider over-critical currents (i.e. beyond hysteresis saturation), whereby extra care must be taken for the numerical simulations. We have considered a design of fixed radii and have optimized the pitch length of each layer in order to have equal reactances for all phases

213

Backstepping controller of five-level three-phase inverter

Directory of Open Access Journals (Sweden)

Full Text Available Multilevel converters are becoming increasingly used in many industrial applications due to the many advantages that they offer. The improvements in the output signal quality, lower Total Harmonic Distortion (THD and many other properties make multilevel converters very attractive for connecting photovoltaic generators to medium voltage grid directly or to be used in a local power supply. In this paper, we focus on the implementation of a three-phase five-level diode clamped inverter and design of a performing nonlinear controller using the Backstepping approach. The control objective is to generate, at the system output, sinusoidal three-phase voltages with amplitude and frequency fixed by the reference signal independently of load variations. The performance study of the multilevel inverter and the designed controller are made by simulations in Matlab/Simulink environment.

Majdoul R.

2014-01-01

214

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

215

CONCEPTUAL THREE PHASE KDD MODEL AND FINANCIAL RESEARCH

Directory of Open Access Journals (Sweden)

Full Text Available KDD model becomes used in financial process. Data Mining tools can be used to improve the efficiency of the professionals. The integration of Data Mining tools with the traditional financial research methods is relatively a new concept. If Data Mining tools for Financial are developed then it make the process fast, cheaper and relatively much more efficient. In this paper we have discussed the three phase model of KDD on Financial Research.

Dr. Simmi Bagga

2013-04-01

216

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

217

Evaluation of Three-Phase Transformerless Photovoltaic Inverter Topologies

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper analyzes and compares three transformerless photovoltaic inverter topologies for three-phase grid connection with the main focus on the safety issues that result from the lack of galvanic isolation. A common-mode model, valid at frequencies lower than 50 kHz, is adopted to study the leakage current paths. The model is validated by both simulation and experimental results. These will be used to compare the selected topologies, and to explain the influence of system unbalance and the...

Kerekes, Tamas; Liserre, Marco; Teodorescu, Remus; Klumpner, C.; Sumner, M.

2009-01-01

218

Analysis and Effects off Unsymmetrically Loaded Three-Phase Network

Directory of Open Access Journals (Sweden)

Full Text Available The paper analyses current and voltage unbalance caused by various unsymmetric loads in MV and HV networks. It refers to a different unbalance definitions and compares them with the values measured by apparatus dedicated to the power quality measurements. If the current unbalance exists, power factors and powers in the electrical lines are not the same as for the symmetrical three-phase loads.

Michal Pokorny

2002-01-01

219

Precise derating of three phase induction motors with unbalanced voltages

International Nuclear Information System (INIS)

Performance analysis of three phase induction motors under supply voltage unbalance conditions is normally conducted using the well-known symmetrical components analysis. In this analysis, the voltage unbalance level at the terminals of the machine is assessed by means of the NEMA or IEC definitions. Both definitions lead to a relatively large error in predicting the performance of a machine. A method has recently been proposed in which, in addition to the voltage unbalance factor (VUF), the phase angle has been taken into account in the analysis. This means that the voltage unbalance factor is regarded as a complex value. This paper shows that although the use of the complex VUF reduces the computational error considerably, it is still high. This is proven by evaluating the derating factor of a three phase induction motor. A method is introduced to determine the derating factor precisely using the complex unbalance factor for an induction motor operating under any unbalanced supply condition. A practical case for derating of a typical three phase squirrel cage induction motor supplied by an unbalanced voltage is studied in the paper

220

Studies in Three Phase Gas-Liquid Fluidised Systems

Available from UMI in association with The British Library. The work is a logical continuation of research started at Aston some years ago when studies were conducted on fermentations in bubble columns. The present work highlights typical design and operating problems that could arise in such systems as waste water, chemical, biochemical and petroleum operations involving three-phase, gas-liquid -solid fluidisation; such systems are in increasing use. It is believed that this is one of few studies concerned with "true" three-phase, gas-liquid-solid fluidised systems, and that this work will contribute significantly to closing some of the gaps in knowledge in this area. The research work was experimentally based and involved studies of the hydrodynamic parameters, phase holdups (gas and solid), particle mixing and segregation, and phase flow dynamics (flow regime and circulation patterns). The studies have focused particularly on the solid behaviour and the influence of properties of solids present on the above parameters in three-phase, gas-liquid-solid fluidised systems containing single particle components and those containing binary and ternary mixtures of particles. All particles were near spherical in shape and two particle sizes and total concentration levels were used. Experiments were carried out in two- and three-dimensional bubble columns. Quantitative results are presented in graphical form and are supported by qualitative results from visual studies which are also shown as schematic diagrams and in photographic form. Gas and solid holdup results are compared for air-water containing single, binary and ternary component particle mixtures. It should be noted that the criteria for selection of the materials used are very important if true three-phase fluidisation is to be achieved: this is very evident when comparing the results with those in the literature. The fluid flow and circulation patterns observed were assessed for validation of the generally accepted patterns, and the author believes that the present work provides more accurate insight into the modelling of liquid circulation in bubble columns. The characteristic bubbly flow at low gas velocity in a two-phase system is suppressed in the three-phase system. The degree of mixing within the system is found to be dependent on flow regime, liquid circulation and the ratio of solid phase physical properties.

Awofisayo, Joyce Ololade

1992-01-01

221

This paper describes an ungrounded common-mode equivalent circuit for a motor driven by a voltage-source PWM inverter. When the capacitance of the rotor was is small, the reversal of the polarities of the common-mode voltage and shaft voltage is observed. In order to model this reversal, a bridge-type equivalent circuit is proposed. On the basis of calculations and experiment, it is found the values and polarity of the shaft voltage can be are accurately determined with the proposed equivalent circuit. Furthermore, the capacitance value of the insulated rotor required to make the shaft voltage equal to or less than the dielectric breakdown voltage of the bearing grease is obtained.

Maetani, Tatsuo; Isomura, Yoshinori; Watanabe, Akihiko; Iimori, Kenichi; Morimoto, Shigeo

222

Intelligent Positioning Fuzzy Servomechanism Under PWM Nonlinear Loads

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish Se desarrolla un servomecanismo difuso de posicionamiento angular inteligente experimental perturbado por cargas no-lineales basadas en transitorios mecánicos generados mediante la modulación de ancho de pulso (PWM). El sistema de posicionamiento difuso desarrollado es capaz de alcanzar la posición [...] angular con gran precisión aún cuando la respuesta es afectada por la aplicación de distintas cargas PWM no lineales. Abstract in english An experimental intelligent angular positioning fuzzy servomechanism excited by a nonlinear load based on a mechanical transient Pulse Width Modulation (PWM) is developed. This fuzzy positioning system is capable of reaching the angular position with high precision even when the response is affected [...] by the application of different PWM nonlinear loads.

D., Rangel; A. L., Rivera; P.D., Alaníz; R., Castañeda; V.M., Castaño.

223

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

224

Scientific Electronic Library Online (English)

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

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

225

Scientific Electronic Library Online (English)

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

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

2012-06-01

226

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)

227

A Novel SVPWM Technology Used in PWM Rectifiers of WPGS

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 gene...

Zhang Junli; Li Yuren; Fu Longfei; Zhang Wenjuan

2013-01-01

228

Performance characteristics of three-phase induction motors

An investigation into the characteristics of three phase, 400 Hz, induction motors of the general type used on aircraft and spacecraft is summarized. Results of laboratory tests are presented and compared with results from a computer program. Representative motors were both tested and simulated under nominal conditions as well as off nominal conditions of temperature, frequency, voltage magnitude, and voltage balance. Good correlation was achieved between simulated and laboratory results. The primary purpose of the program was to verify the simulation accuracy of the computer program, which in turn will be used as an analytical tool to support the shuttle orbiter.

Wood, M. E.

1977-01-01

229

Partial Resonances of Three-Phase Composites at Long Wavelengths

We investigate the behaviour of a three-phase composite, structured as a hexagonal array of coated cylinders, when the sum of the dielectric constants of the core and shell equals zero. In such cases, the absorption of the composite is the same as the absorption of a periodic array of solid cylinders of core material and radius equal to the outer radius of the original coated cylinder. When the sum of the dielectric constants of the shell and matrix equals zero, the composite has the same absorption as a periodic array of solid cylinders of core material, and radius exceeding the shell radius.

Nicorovici, N A; McPhedran, R C; Milton, G W

2006-01-01

230

Three phase R. F. systems for superconducting cyclotrons

Energy Technology Data Exchange (ETDEWEB)

This article describes and illustrates the three phase r.f. system for superconducting cyclotrons. It is discussed that the initial design of the MSU K500 cyclotron r.f. system has since been changed and these changes are reviewed. The author describes how, after several evolutions, there is now a successful moving short for the 6 dee stems. The stem current flowing on the 4-inch O.D. inner conductor is 2600 amps RMS, resulting in a linear current density of 206 amps per inch. Problems with the operation of the r.f. system are also reviewed.

Riedel, J.

1983-08-01

231

Three-Phase Unbalanced Load Flow Tool for Distribution Networks

Digital Repository Infrastructure Vision for European Research (DRIVER)

This work develops a three-phase unbalanced load flow tool tailored for radial distribution networks based on Matlab®. The tool can be used to assess steady-state voltage variations, thermal limits of grid components and power losses in radial MV-LV networks with photovoltaic (PV) generators where most of the systems are single phase. New ancillary service such as static reactive power support by PV inverters can be also merged together with the load flow solution tool and thus, the impact o...

Demirok, Erhan; Kjær, Søren Bækhøj; Sera, Dezso; Teodorescu, Remus

2012-01-01

232

A DSP controlled one-to-three phase matrix converter

Energy Technology Data Exchange (ETDEWEB)

This paper deals with the theoretical analysis computer simulation and experimental results of IM fed by a one-to-three phase matrix converter which offers a unique solution for single phase electric traction applications. The proposed drive in comparison with currently used conventional drives reduces the number of power switching elements of the converter, which increases drives dependability and brings lower investment in power electronics used in drive. Further advantage is that the converter is controlled with nearly unity power factor which cuts down the operational expenses and offers higher overall performance of the drive. (orig.) 6 refs.

Dubovsky, J.; Dobrucly, B; Tabacek, R.; Havrila, R. [Department of Electric Traction and Energetics Faculty of Electrical Engineering, University of Zilina (Slovakia)

1997-12-31

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

Energy Technology Data Exchange (ETDEWEB)

In this paper, a photovoltaic (PV) system, with maximum power point tracking (MPPT), connected to a three phase grid is presented. The connection of photovoltaic system on the grid takes place in one stage using voltage source inverter (VSI). For a better utilization of the photovoltaic system, the control strategy applied is based on p-q theory. According to this strategy during sunlight the system sends active power to the grid and at the same time compensates the reactive power of the load. In case there is no sunlight (during the night for instance), the inverter only compensates the reactive power of the load. In this paper the use of p-q theory to supply the grid with active power and compensate the reactive power of the load is investigated. The advantage of this control strategy is that the photovoltaic system is operated the whole day. Furthermore, the p-q theory uses simple algebraic calculations without demanding the use of PLL to synchronize the inverter with the grid. (author)

Tsengenes, Georgios; Adamidis, Georgios [Department of Electrical Engineering and Computer Engineering, Democritus University of Thrace, University Campus Kimmeria, 67100 Xanthi (Greece)

2011-01-15

235

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

236

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

237

Advanced computational model for three-phase slurry reactors

International Nuclear Information System (INIS)

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

238

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.

239

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

240

A fuzzy controlled three-phase centrifuge for waste separation

Energy Technology Data Exchange (ETDEWEB)

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.

Parkinson, W.J.; Smith, R.E. [Los Alamos National Lab., NM (United States); Miller, N. [Centech, Inc., Casper, WY (United States)

1998-02-01

241

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

242

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

243

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

244

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

245

Three-phase radionuclide bone imaging in sports medicine

International Nuclear Information System (INIS)

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

246

Three-phase unbalanced load flow tool for distribution networks

Energy Technology Data Exchange (ETDEWEB)

This work develops a three-phase unbalanced load flow tool tailored for radial distribution networks based on Matlab {sup registered}. The tool can be used to assess steady-state voltage variations, thermal limits of grid components and power losses in radial MV-LV networks with photovoltaic (PV) generators where most of the system are single phase. New ancillary service such as static reactive power support by PV inverters can be also merged together with the load flow solution tool and thus, the impact of the various reactive power control strategies on the steady-state grid operation can be simply investigated. Performance of the load flow solutions tool in the sense of resulting bus voltage magnitudes is compared and validated with IEEE 13-bus test feeder. (orig.)

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

2012-07-01

247

Evaluation of Three-Phase Transformerless Photovoltaic Inverter Topologies

DEFF Research Database (Denmark)

This paper analyzes and compares three transformerless photovoltaic inverter topologies for three-phase grid connection with the main focus on the safety issues that result from the lack of galvanic isolation. A common-mode model, valid at frequencies lower than 50 kHz, is adopted to study the leakage current paths. The model is validated by both simulation and experimental results. These will be used to compare the selected topologies, and to explain the influence of system unbalance and the neutral conductor inductance on the leakage current. It will be demonstrated that the later has a crucial influence. Finally, a comparison of the selected topologies is carried out, based on the adopted modulation, connection of the neutral and its inductance, effects of unbalance conditions, component ratings, output voltage levels, and filter size. Udgivelsesdato: September

Kerekes, Tamas; Liserre, Marco

2009-01-01

248

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)

249

Myositis ossificans and the three-phase bone scan

Energy Technology Data Exchange (ETDEWEB)

Myositis ossificans circumscripta (or paraosteoarthropathy) in paraplegics has been a well known entity since its classic description in 1918 by Dejerine and Ceillier. The disease is characterized by ectopic bone formation, primarily occurring in the particular soft tissues of the hips and knees. Hypotheses concerning its origin have been proposed, but its etiology is still unknown. Myositis ossificans can occur after traumatic injury, but develops in paraplegics without apparent injury in the involved regions. Radionuclide techniques have been used in the evaluation of myositis ossificans, particularly with serial studies to stage the activity of the disease. The author reports a case of myositis ossificans in a paraplegic that emphasizes the benefit of the three-phase bone scan in the early diagnosis of this disorder.

Drane, W.E.

1984-01-01

250

Myositis ossificans and the three-phase bone scan

International Nuclear Information System (INIS)

Myositis ossificans circumscripta (or paraosteoarthropathy) in paraplegics has been a well known entity since its classic description in 1918 by Dejerine and Ceillier. The disease is characterized by ectopic bone formation, primarily occurring in the particular soft tissues of the hips and knees. Hypotheses concerning its origin have been proposed, but its etiology is still unknown. Myositis ossificans can occur after traumatic injury, but develops in paraplegics without apparent injury in the involved regions. Radionuclide techniques have been used in the evaluation of myositis ossificans, particularly with serial studies to stage the activity of the disease. The author reports a case of myositis ossificans in a paraplegic that emphasizes the benefit of the three-phase bone scan in the early diagnosis of this disorder

251

Three-Phase Unbalanced Load Flow Tool for Distribution Networks

DEFF Research Database (Denmark)

This work develops a three-phase unbalanced load flow tool tailored for radial distribution networks based on Matlab®. The tool can be used to assess steady-state voltage variations, thermal limits of grid components and power losses in radial MV-LV networks with photovoltaic (PV) generators where most of the systems are single phase. New ancillary service such as static reactive power support by PV inverters can be also merged together with the load flow solution tool and thus, the impact of the various reactive power control strategies on the steady-state grid operation can be simply investigated. Performance of the load flow solution tool in the sense of resulting bus voltage magnitudes is compared and validated with IEEE 13-bus test feeder.

Demirok, Erhan; Kjær, SØren BækhØj

2012-01-01

252

Phase detector for three-phase power factor controller

A phase detector for the three phase power factor controller (PFC) is described. The phase detector for each phase includes an operational amplifier which senses the current phase angle for that phase by sensing the voltage across the phase thyristor. Common mode rejection is achieved by providing positive feedback between the input and output of the voltage sensing operational amplifier. this feedback preferably comprises a resistor connected between the output and input of the operational amplifier. The novelty of the invention resides in providing positive feedback such that switching of the operational amplifier is synchronized with switching of the voltage across the thyristor. The invention provides a solution to problems associated with high common mode voltage and enables use of lower cost components than would be required by other approaches.

Nola, F. J. (inventor)

1984-01-01

253

Cellular automata approach to three-phase traffic theory

International Nuclear Information System (INIS)

The cellular automata (CA) approach to traffic modelling is extended to allow for spatially homogeneous steady state solutions that cover a two-dimensional region in the flow-density plane. Hence these models fulfil a basic postulate of a three-phase traffic theory proposed by Kerner. This is achieved by a synchronization distance, within which a vehicle always tries to adjust its speed to that of the vehicle in front. In the CA models presented, the modelling of the free and safe speeds, the slow-to-start rules as well as some contributions to noise are based on the ideas of the Nagel-Schreckenberg-type modelling. It is shown that the proposed CA models can be very transparent and still reproduce the two main types of congested patterns (the general pattern and the synchronized flow pattern) as well as their dependence on the flows near an on-ramp, in qualitative agreement with the recently developed continuum version of the three-phase traffic theory (Kerner B S and Klenov S L 2002 J. Phys. A: Math. Gen. 35 L31 ). These features are qualitatively different from those in previously considered CA traffic models. The probability of the breakdown phenomenon (i.e. of the phase transition from free flow to synchronized flow) as function of the flow rate to the on-ramp and of the flow rate on the road upstream of the on-ramp is investigated. The capacity drops at the on-ramp which occur due to the formation of different congested patterns are calculatedatterns are calculated

254

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

255

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

256

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

257

Voltage Sag Mitigation by PWM Autotransformer Technique

Directory of Open Access Journals (Sweden)

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

ASHOK L. VAGHAMSHI

2012-06-01

258

Realise of PWM-generating based on FPGA

International Nuclear Information System (INIS)

The power supply digital controllers of Shanghai Synchrotron Radiation Facility(SSRF) make use of the PWM (pulse width modulation) wave as the feedback to the power-electrical devices, so as to obtain constant current of high accuracy and stability. The design of PWM wave generation structure in FPGA is good for a compact controller,and the reduction of the usage of Integrated Circuits (ICs) decreases the interference from the noise among the ICs, hence better performance of the controller. In addition, FPGA can be programmed circularly at any time,so as to optimize the structure design and make a maximum use of the advantage of FPGA. As a part of transplanting the complete function of the DSP (digital signal processor/processing), realizing the generation of PWM wave in FPGA is feasible. In this paper, we report progress in this regard at SSRF. (authors)

259

Neural network based PWM AC chopper fed induction motor drive

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, a new Simulink model for a neural network controlled PWM AC chopper fed single phase induction motor is proposed. Closed loop speed control is achieved using a neural network controller. To maintain a constant fluid flow with a variation in pressure head, drives like fan and pump are operated with closed loop speed control. The need to improve the quality and reliability of the drive circuit has increased because of the growing demand for improving the performance of motor drives. With the increased availability of MOSFET's and IGBT's, PWM converters can be used efficiently in low and medium power applications. From the simulation studies, it is seen that the PWM AC chopper has a better harmonic spectrum and lesser copper loss than the Phase controlled AC chopper. It is observed that the drive system with the proposed model produces better dynamic performance, reduced overshoot and fast transient response. .

Venkatesan Jamuna

2009-01-01

260

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

261

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-08-13

262

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.

263

Mathematical modeling of a three-phase trickle bed reactor

Directory of Open Access Journals (Sweden)

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

J. D. Silva

2012-09-01

264

Three-phase scintimetry in osteonecrosis of the knee.

Three-phase scintimetry with 99mTc MDP was analyzed in 40 patients with a clinical history of spontaneous onset of knee pain and a focal static isotope uptake in the femoral condyle indicating osteonecrosis. A strong correlation was found between pool-phase ratios and the static ratios. The pool-phase study did not add to the information obtained from the flow phase and static studies. There was a characteristic change of the pattern of the early flow-phase curves with the duration since the onset of symptoms indicating hyperemia early in the disease. A persistent high flow-phase and static-uptake ratio 6-12 months after the onset of symptoms correlated positively with a poor clinical and radiographic outcome. The 10 patients with a good prognosis had, as a group, a more rapid decrease in isotope uptake after 6 months. There was a positive correlation between a high static uptake ratio and the size of the lesion, and subsequently with the clinical and radiographic outcome. 30 patients developed arthrosis and/or severe clinical symptoms. Five of the 10 patients who did not develop arthrosis never developed radiographic evidence of osteonecrosis. PMID:2360427

al-Rowaih, A; Wingstrand, H; Lindstrand, A; Björkengren, A; Thorngren, K G; Gustafson, T

1990-04-01

265

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

266

Deterministic microscopic three-phase traffic flow models

International Nuclear Information System (INIS)

Two different deterministic microscopic traffic flow models, which are in the context of the Kerner's there-phase traffic theory, are introduced. In an acceleration time delay model (ATD model), different time delays in driver acceleration associated with driver behaviour in various local driving situations are explicitly incorporated into the model. Vehicle acceleration depends on local traffic situation, i.e., whether a driver is within the free flow or synchronized flow or else wide moving jam traffic phase. In a speed adaptation model (SA model), vehicle speed adaptation occurs in synchronized flow depending on driving conditions. It is found that the ATD and SA models show spatiotemporal congested traffic patterns that are adequate with empirical results. In the ATD and SA models, the onset of congestion in free flow at a freeway bottleneck is associated with a first-order phase transition from free flow to synchronized flow; moving jams emerge spontaneously in synchronized flow only. Differences between the ATD and SA models are studied. A comparison of the ATD and SA models with stochastic models in the context of three-phase traffic theory is made. A critical discussion of earlier traffic flow theories and models based on the fundamental diagram approach is presented

267

A simulation model for three-phase gravity separators

Energy Technology Data Exchange (ETDEWEB)

Design of separators has up to now mainly been based on the API design rules. It is then assumed that there is stratified flow in the separator, and that the flow in each phase layer is completely uniform. All effects from non-ideal flow, inlet/outlets and internal equipment to enhance separation are neglected. The residence time of the phases can then be calculated, and the separation efficiency estimated using experience and laboratory data to estimate the sizes of the dispersed fluid particles. The API rules are proven, but the method is approximate and considerable safety factors are needed. When weight and space are critical, as on offshore platforms or sub-sea, the size of the vessel should be as small as possible. More accurate design methods are thus required. Computational fluid dynamics (CFD) has been used in single-phase simulations of separators assuming, as in the API rules, stratified flow. Several assumptions about the positions of the phase interfaces and the inlet flow pattern must then be made. To fully exploit the power of CFD, a complete multiphase separator model with the fundamental physics must be formulated. In this presentation such a computational model for three-phase gas, oil and water flow in a gravity separator is described. (author)

Hallanger, A.; Sveberg, K.; Anfinsen, N.; Soenstaboe, F. [Christian Michelsen Research AS, Fantoft (Norway)

1995-09-01

268

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

269

Dislocation stability in three-phase nanocomposites with imperfect interface

Interface imperfection can significantly affect the mechanical properties and failure mechanisms as well as the strength and toughness of nanocomposites. The elastic behavior of a screw dislocation in nanoscale coating with imperfect interface is studied in the three-phase composite cylinder model. The interface between inner nanoinhomogeneity and intermediate coating is assumed as perfectly bonded. The bonding between intermediate coating and outer matrix is considered to be imperfect with the assumption that interface imperfection is uniform, and a linear spring model is adopted to describe the weakness of imperfect interface. The explicit expression for image force acting on dislocation is obtained by means of a complex variable method. The analytic results indicate that inner interface effect and outer interface imperfection, simultaneously taken into account, would influence greatly image force, equilibrium position and stability of dislocation, and various critical parameters that would change dislocation stability. The weaker interface is a very strong trap for glide dislocation and, thus, a more effective barrier for slip transmission.

Zhao, Ying-Xin; Liu, You-Wen; Fang, Qi-Hong

2014-10-01

270

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

271

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

272

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)

273

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

274

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

275

Compensation on Hall effect sensor of PWM switching control

International Nuclear Information System (INIS)

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

276

A new Zero-Current-Transition PWM switching cell

Energy Technology Data Exchange (ETDEWEB)

In this paper a new Zero-Current-Transition (ZCT) PWM switching cell is presented. The proposed switching cell is composed of the normal hard-switched PWM cell (consisting of one active switch and one passive switch), plus as auxiliary circuit. The auxiliary circuit is inactive during the ON ad OFF intervals of the switches in the normal PWM switch. The transitions between the two states are controlled by the auxiliary circuit. Prior to turn-off, the current through the active switch in the PWM cell is forced to zero, thus the turn-off losses of the active switch are practically eliminated. At turn-on the auxiliary circuit slows down the growing rate of the current through the main switch. Thus, turn-on losses are also very much reduced. The active switch operates under ZCT conditions, the passive switch (diode) has a controlled reverse recovery, while the switch in the auxiliary circuit operates under Zero-Current-Switching (ZCS) conditions. (orig.) 3 refs.

Grigore, V. [Electronics and Telecommunications Faculty, `Politechnica` University Bucharest (Romania); Kyyrae, J. [Helsinki University of Technology, Otaniemi (Finland): Institute of Intelligent Power Electronics

1997-12-31

277

A new Zero-Voltage-Transition PWM switching cell

Energy Technology Data Exchange (ETDEWEB)

In this paper a new Zero-Voltage-Transition (ZVT) PWM switching cell is presented. The proposed switching cell is composed of the normal hard-switched PWM cell (consisting of one active switch and one passive switch), plus an auxiliary circuit (consisting of one active switch and some reactive components). The auxiliary circuit is inactive during the ON and OFF intervals of the switches in the normal PWM switch. However, the transitions between the two states are controlled by the auxiliary circuit. Prior to turn-on, the voltage across the active switch in the PWM cell is forced to zero, thus the turn-on losses of the active switch are practically eliminated. At turn-off the auxiliary circuit behaves like a non-dissipative passive snubber reducing the turn-off losses to a great extent. Zero-Voltage-Transition switching technique almost eliminates switching losses. The active switch operates under ZVT conditions, the passive switch (diode) has a controlled reverse recovery, and the switch in the auxiliary circuit operates under Zero-Current-Switching (ZCS) conditions. (orig.) 6 refs.

Grigore, V. [Electronics and Telecommunications Faculty `Politebuica` University Bucharest (Romania); Kyyrae, J. [Helsinki University of Technology, Otaniemi (Finland): Institute of Intelligent Power Electronics

1997-12-31

278

Simulation of Single-Phase Cascade Multilevel PWM Inverters

Directory of Open Access Journals (Sweden)

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

Felicia ?chiop

2008-05-01

279

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

280

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

281

Boosted PWM open loop control of hydraulic proportional valves

International Nuclear Information System (INIS)

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

282

Energy Technology Data Exchange (ETDEWEB)

Three-Phase Voltage Source Converters (VSCs) are finding widespread applications in grid integrated power conversion systems. The control systems of such VSCs are in an increasing number of these applications required to operate during voltage disturbances and unbalanced conditions. Control systems designed for grid side voltagesensor-less operation are at the same time becoming attractive due to the continuous drive for cost reduction and increased reliability of VSCs, but are not commonly applied for operation during unbalanced conditions. Methods for voltage-sensor-less grid synchronization and control of VSCs under unbalanced grid voltage conditions will therefore be the main focus of this Thesis. Estimation methods based on the concept of Virtual Flux, considering the integral of the converter voltage in analogy to the flux of an electric machine, are among the simplest and most well known techniques for achieving voltage-sensor-less grid synchronization. Most of the established techniques for Virtual Flux estimation are, however, either sensitive to grid frequency variations or they are not easily adaptable for operation under unbalanced grid voltage conditions. This Thesis addresses both these issues by proposing a simple approach for Virtual Flux estimation by utilizing a frequency-adaptive filter based on a Second Order Generalized Integrator (SOGI). The proposed approach can be used to achieve on-line frequency-adaptive varieties of conventional strategies for Virtual Flux estimation. The main advantage is, however, that the SOGI-based Virtual Flux estimation can be arranged in a structure that achieves inherent symmetrical component sequence separation under unbalanced conditions. The proposed method for Virtual Flux estimation can be used as a general basis for voltage-sensor-less grid synchronization and control during unbalanced conditions. In this Thesis, the estimated Virtual Flux signals are used to develop a flexible strategy for control of active and reactive power flow, formulated as generalized equations for current reference calculation. A simple, but general, implementation is therefore achieved, where the control objective and the power flow characteristics can be selected according to the requirements of any particular application. Thus, the same control structure can be used to achieve for instance balanced sinusoidal currents or elimination of double frequency active power oscillations during unbalanced conditions. In case of voltage sags, current references corresponding to a specified active or reactive power flow might exceed the current capability of the converter. The limits for active and reactive power transfer during unbalanced conditions have therefore been analyzed, and generalized strategies for current reference calculation when operating under current limitations have been derived. The specified objectives for active and reactive power flow characteristics can therefore be maintained during unbalanced grid conditions, while the average active and reactive power flow is limited to keep the current references within safe values. All concepts and techniques proposed in this Thesis have been verified by simulations and laboratory experiments. The SOGI-based method for Virtual Flux estimation and the strategies for active and reactive power control with current limitation can also be easily adapted for a wide range of applications and can be combined with various types of inner loop control structures. Therefore, the proposed approach can potentially be used as a general basis for Virtual Flux-based voltage-sensor-less operation of VSCs under unbalanced grid voltage conditions.(Author)

Suul, Jon Are

2012-03-15

283

Capillary effects on gas hydrate three-phase stability in marine sediments

We study the three-phase (Liquid + Gas + Hydrate) stability of the methane hydrate system in marine sediments by considering the capillary effects on both hydrate and free gas phases. The aqueous CH4 solubilities required for forming hydrate (L+H) and free gas (L+G) in different pore sizes can be met in a three-phase zone. The top of the three-phase zone shifts upward in sediments as the water depth increases and the mean pore size decreases. The thickness of the three-phase zone increases as the pore size distribution widens. The top of the three-phase zone can either overlie the three-phase stability depth at deepwater Blake Ridge or underlie the three-phase stability depth at Hydrate Ridge in shallow water. Our model prediction is compatible with worldwide observations that the bottom-simulating reflector is systematically shifted upward relative to the bulk equilibrium depth as water depth (pressure) is increased. The gas hydrate and free gas saturations of the three-phase zone at Blake Ridge Comparison of the globally compiled BSR temperatures with the three-phase equilibrium curves for the systems of pure CH4 + 3.5 wt.% seawater (solid line) and pure CH4 + 2.0 wt.% seawater (dotted line). The discrepancies between the observed BSR temperature and the calculated three-phase temperature are systematically larger in deep water than in shallow water.

Liu, X.; Flemings, P. B.

2013-12-01

284

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

285

Digital Repository Infrastructure Vision for European Research (DRIVER)

For islanded microgrids, droop-based control concepts have been developed both in single and three-phase variants. The three-phase controllers often assume a balanced network; hence, unbalance sharing and/or mitigation remains a challenging issue. Therefore, in this paper, unbalance is considered in a three-phase islanded microgrid in which the distributed generation (DG) units are operated by the voltage-based droop (VBD) control. For this purpose, the VBD control, which has been developed f...

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

2013-01-01

286

Control of a Three Phase Induction Motor using Single Phase Supply

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 Ind...

G R Sreehitha, A. Krishna Teja

2012-01-01

287

Apparent permeability of electrical steel under PWM magnetisation

International Nuclear Information System (INIS)

In recent years much attention has been paid to material performance under pulse width modulation (PWM) excitation conditions, which is of increasing importance to motor applications particularly in energy efficient variable speed drive systems. It is well known that in general, losses increase significantly with reducing modulation index, the increase depending on parameters such as silicon contents, thickness and grain size. The effect of the PWM waveform on permeability has attracted little attention until now. So in this paper its influence on the permeability of electrical steel is analysed and characterised. A prediction approach based on the permeability under sine wave excitation and total harmonic distortion is introduced which results in errors below 10% for non-electrical steel at 1.5 T

288

Soft Switched Multi-Output PWM DC-DC Converter

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, a new soft switched cell that overcomes most of the drawbacks of the normal "hard switched-pulse width modulation" converter is proposed to contrive a new family of soft switched PWM converters. All of the semiconductor devices in this converter are turned on and off under exact or near zero voltage switching (ZVS and/or zero current switching (ZCS. No additional voltage and current stresses on the main switch and main diode occur. A push-pull converter equipped with the proposed snubber cell is analyzed in detail. The predicted operation principles and theoretical analysis of the presented converter are verified with a prototype of a 50W PWM push-pull multi-output converter with insulated MOSFET and for regulation of slave outputs magnetic amplifier post regulators are considered as post regulators. Moreover; this multioutput converter has a simple structure, low cost, and ease of control circuitry.

Rashmi Sharma

2013-07-01

289

Prediction of power losses in silicon iron sheets under PWM voltage supply

International Nuclear Information System (INIS)

The behavior of iron losses in silicon iron steels submitted to a PWM voltage is studied. The influence of modulation parameters (the depth of modulation and the number of eliminated harmonics) is clarified. In particular, the idea of an equivalent alternating pulse voltage that gives the same iron losses as the PWM voltage is established. An estimation formula for iron losses under the PWM voltage is developed based on the loss separation model and the voltage form factor. ((orig.))

290

A quantitative dimming method for LED based on PWM

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

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

2012-10-01

291

Asymmetric Switching For A PWM H-Bridge Power Circuit

Only two of four switches interrupt substantial current. An asymmetric timing scheme improves design and operation of pulse-width-modulation (PWM) H-bridge switch-and-transformer circuit. Circuit part of dc-to-dc converter or dc-to-ac inverter; in either case, output current or voltage regulated by adjusting times of opening and closing of semiconductor switches 1 through 4 to adjust durations of current pulses in primary winding of transformer.

Wong, See-Pok

1995-01-01

292

Comparison of chaotic PWM algorithms for electric vehicle motor drives

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents a comparison of two chaoized PWM algorithms for motor drives in the electric vehicle (EV), which are the chaotic sinusoidal pulse width modulation (SPWM) and the chaotic space-vector pulse width modulation (SVPWM). The SPWM scheme can be chaoized by three modulation methods, including the chaotically amplitude-modulated frequency modulation (CAFM), the chaotically position-modulated position modulation (CPPM), and the hybrid chaotic frequency modulation (HCFM), while the c...

Zhang, Z.; Ching, Tw; Lee, Cht; Liu, C.

2012-01-01

293

HIGH EFFICIENCY BRIDGELESS PWM CUK CONVERTER WITH SOFT SWITCHING TECHNIQUE

Digital Repository Infrastructure Vision for European Research (DRIVER)

High efficiency bridgeless single-phase ac-dc PWM cuk converter with soft-switching (ZVS) technique is proposed. This paper emphasizes more on the converter efficiency. The conduction losses and input current harmonics of the proposed converter is very less due to the absence of the input diode bridge and also during each switching cycle, only two semiconductor switches are present in the current path unlike other conventional Cuk converters. Soft switching (ZVS)technique is applied by using ...

Anjan Kumar Sahoo, Sarika Kalra

2013-01-01

294

PWM Soft-Switched Converters With A Single Active Switch

Energy Technology Data Exchange (ETDEWEB)

This paper presents several converters which, having only a single active switch, are able to operate with PWM characteristics in a soft switching way. In addition such converters can work in high switching frequencies for wide load range without great limitations. In order to illustrate the operating principles of these converters a detailed analysis, including simulations and experimental tests are carried out. The validity of these converters is assured by the obtained results. 10 refs., 11 figs., 1 tab.

NONE

1997-10-20

295

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

296

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

297

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

298

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

299

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

1999-01-01

300

Determining the optimal operator allocation using a three-phase methodology

This paper presents the operator allocation decision in labor-intensive manufacturing system using a three-phase methodology. A two-phase methodology from literatures has been extended to a three-phase methodology which in a three-phase methodology, operators' performance is evaluated before the allocation is made. The evaluation of operators' performance in Phase 1 is realized as a requirement in operator allocation decision because it will affect the production system's performance. In Phase 2, the used of computer simulation offered flexibility in determining inputs and outputs of each operator allocation alternative. Finally, in Phase 3 the optimal operator allocation is concluded. The combination of these three phases is essential because it includes all important factors. Hence, it will assist the management of the manufacturing companies, especially SMEs in providing ideas to determine an optimal operator allocation. Based on these findings a three-phase methodology improves the current operator allocation.

Rani, Ruzanita Mat; Ismail, Wan Rosmanira; Ab Rahman, Mohd Nizam

2014-09-01

301

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

International Nuclear Information System (INIS)

d flow changes in 4 cases and soft tissue tumors were seen in 4 cases. Three phase bone scan was more sensitive than delayed whole body bone scan in detecting the abnormal sites (p0.05) The sensitivity of detecting tumors in blood flow and blood pool phase,delayed phase were respectively lower than in three phase bone scan (p<0.001).Conclusion: It is more sensitivity of detecting tumor lesions in three phase bone scan than in delayed phase whole body bone scan and the changes of blood flow and soft tissue can be seen in three phase bone scan. So it is more suitable way to improve the sensitivity of detecting abnormal sites in three-phase bone scan. (authors)

302

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

International Nuclear Information System (INIS)

The relationship between lymphocytes induced by PWM (pokeweed mitogen) and LPS (lipopolysaccharide) was investigated by means of 3H-TdR incorporation. The study showed that, in vitro, PWM-induced cells were able to promote the stimulating effect of LPS to B lymphocytes. 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 ?-ray, 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, while treated with 60Co ?-rays, the incorporation value in LPS-induced cells approached normal level, meanwhile, the incorporation value in PEM-induced cells reduced significantly and the stimulating effect of PWM-induced cells on LPS-induced cells became much weaker. The facts described above demonstrated that PWM-induced cells have the function of T-helper cells and play more important role in the synergy than LPS-induced cells

303

Directory of Open Access Journals (Sweden)

Full Text Available This paper attempts to analyse the dominant harmonics present in sinusoidal PWM inverter output with AC source . A new technique for reducing this harmonics in PWM inverter output by modifying the reference waveform is proposed, by using MATLAB simulations.

G.SUDHA RANI

2013-04-01

304

Multicarrier trapezoidal PWM strategies based on control freedom degree for MSMI

Directory of Open Access Journals (Sweden)

Full Text Available This work proposes an additional clew for the carrier based PWM methods on control of multilevel inverters which is based on the combination of the Control Freedom Degree (CFD and novel carrier/reference signals for multilevel cascaded inverter. The significance of the proposed CFD clew on multilevel PWM techniques are verified and well demonstrated by simulation for chosen five level inverter. This paper presents a novel approach for controlling the harmonics of output voltage of chosen Cascaded MultiLevel Inverter (CMLI employing trapezoidal PWM switching strategies. Sub Harmonic PWM (SHPWM, Phase Shift PWM (PSPWM, Variable Frequency PWM (VFPWM and Carrier Overlapping PWM (COPWM techniques employed are evaluated for various modulation indices using spectrum of the output voltage and other performance measures such as crest factor, form factor etc and the use of inverter state redundancies to perform additional application specific control tasks. This paper focusses on MultiCarrier Trapezoidal PWM (MCTPWM techniques with Phase Disposition (PD, Phase Shift (PS, Variable Frequency (VF and Carrier Overlapping (CO of carrier for the chosen CMLI. Simulations are performed using MATLAB/SIMULINK. It is observed that PD and CO methods provide output with relatively low distortion. It is also observed that CO is found to perform better since it provides relatively higher fundamental RMS output voltage and relatively lower stress on the devices.

R. Bensraj

2010-05-01

305

A constant frequency series-resonant dc-dc converter with PWM controlled output

A converter composed of a pulsewidth-modulated (PWM) regulator and a resonant converter that operates at a constant frequency is proposed. The output voltage is regulated by a PWM control technique. In contrast to the usual frequency-control technique, this converter has relatively simple control circuits and high conversion efficiency.

Kuwabara, Kohji; Chida, Jun; Miyachika, Eiji

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

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

308

Simulink Implementation of PWM Strategies for Diode Clamped MLI

Directory of Open Access Journals (Sweden)

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

V.Harish

2014-04-01

309

Full Wave Mode ZVT-PWM DC-DC Converters

Energy Technology Data Exchange (ETDEWEB)

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

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

2001-06-01

310

THD Analysis of Cascaded Mli for Various PWM Techniques

Directory of Open Access Journals (Sweden)

Full Text Available Cascaded inverters are ideal for connecting renewable energy sources with an AC grid, because of the need for separate dc sources, which is the case in applications such as photo voltaics or fuel cells. The inverter could be controlled to either regulate the power factor of the current drawn from the source or the bus voltage of the electrical system where the inverter was connected. The modulation techniques are crucial in operating any inverter at desired conditions. In this paper different pwm techniques are implemented for three level and five level cascaded mli and THD variation is analysed with variation of modulation index.

K.L.Dheeraj

2014-05-01

311

Multi-carrier PWM techniques: a critical evaluation

Energy Technology Data Exchange (ETDEWEB)

High power, low frequency multi-level pulse-width modulated (PWM) inverters necessitate switching techniques that multi-sample the reference wave form, typically being sinusoidal. These commutation techniques are based on multi-carrier wave forms with respect to amplitude, where carrier waveforms are displaced by contiguous increments of the reference wave form amplitude, or with respect to time where carrier wave forms are time displaced by proportional increments of the reference wave forms. In this paper, a critical evaluation of both the aforementioned techniques is provided along with discussion on harmonic spectrum improvements that have been verified through circuit simulation. (author). 9 figs., 7 refs.

Agelidis, V.G.; O`Sullivan, S. [Curtin University of Technology, Bentley, WA (Australia)

1995-12-31

312

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

313

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

314

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

Directory of Open Access Journals (Sweden)

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

Yanwei Zheng

2013-08-01

315

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

316

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

317

Study on three-phase vapour-liquid-solid equilibrium of binary deuterium-helium system

International Nuclear Information System (INIS)

The line of three-phase vapour-liquid-solid equilibrium of binary eD2-He4 system has been measured from the triple point of deuterium up to the pressure of approximately 60 atm. The He4 solubility in deuterium on three-phase line has been estimated. The difference in effect of Ne and 4He impurities on the solidification temperature of hydrogen isotopes is considered

318

POWER FACTOR IMPROVEMENT IN THREE PHASE AC-AC CONVERTER THROUGH MODIFIED SPWM

Digital Repository Infrastructure Vision for European Research (DRIVER)

Recently, a new generation of ac-ac single-phase and three-phase power converters with more commutations per half cycle has been proposed for ac power due to the increasing availability and power capability of high frequency controlled-on and off power emiconductor switching devices. This paper presents three phase ac-acconverter whose control strategy is based on modified sinusoidal ulse-width modulation switching technique. As majority of the industrial loads are being inductive, the pow...

P.VASUKI,; Mahalakshmi, R.

2011-01-01

319

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

320

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

A novel three-phase phase-locked loop solution is proposed based on D-Q transformation aiming at the AC-DC rectifier with high efficiency and high power factor. The phase-locked loop is implemented digitally using the Xilinx blockset integrated with Matlab/Simulink. The three-phase digital phase-locked loop (TDPLL) is elaborately designed with the parameters defined in detail. The AC-DC converter (rectifier) model with the ...

Xuegui Zhu; Zhihong Fu; Xiangfeng Su

2013-01-01

321

PWM Based Automatic Closed Loop Speed Control of DC Motor

Directory of Open Access Journals (Sweden)

Full Text Available The electric drive systems used in many industrial applications require higher performance, reliability, variable speed due to its ease of controllability. The speed control of DC motor is very crucial in applications where precision and protection are of essence. Purpose of a motor speed controller is to take a signal representing the required speed and to drive a motor at that speed. Microcontrollers can provide easy control of DC motor. Microcontroller based speed control system consist of electronic component, microcontroller and the LCD. In this paper, implementation of the ATmega8L microcontroller for speed control of DC motor fed by a DC chopper has been investigated. The chopper is driven by a high frequency PWM signal. Controlling the PWM duty cycle is equivalent to controlling the motor terminal voltage, which in turn adjusts directly the motor speed. This work is a practical one and high feasibility according to economic point of view and accuracy. In this work, development of hardware and software of the close loop dc motor speed control system have been explained and illustrated. The desired objective is to achieve a system with the constant speed at any load condition. That means motor will run at a fixed speed instead of varying with amount of load.

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

2012-04-01

322

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

323

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper analyses current and voltage unbalance caused by various unsymmetric loads in MV and HV networks. It refers to a different unbalance definitions and compares them with the values measured by apparatus dedicated to the power quality measurements. If the current unbalance exists, power factors and powers in the electrical lines are not the same as for the symmetrical three-phase loads.

The paper analyses current and voltage unbalance caused by various unsymme...

Milan Novak; Alena Otcenaskova; Juraj Altus; Michal Pokorny

2002-01-01

324

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

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

2014-04-01

325

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.

326

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

327

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

328

Soft-switching PWM full-bridge converters topologies, control, and design

Soft-switching PWM full-bridge converters have been widely used in medium-to-high power dc-dc conversions for topological simplicity, easy control and high efficiency. Early works on soft-switching PWM full-bridge converter by many researchers included various topologies and modulation strategies. However, these works were scattered, and the relationship among these topologies and modulation strategies had not been revealed. This book intends to describe systematically the soft-switching techniques for pulse-width modulation (PWM) full-bridge converters, including the topologies, control and

Ruan, Xinbo

2014-01-01

329

...2010-07-01 false Low- and medium-voltage circuits serving three-phase alternating...MINES Underground Low- and Medium-Voltage Alternating Current Circuits § 75.900 Low- and medium-voltage circuits serving three-phase...

2010-07-01

330

30 CFR 75.901 - Protection of low- and medium-voltage three-phase circuits used underground.

...must be installed to encircle all three phase conductors. Equipment safety grounding...current transformers. (5) Each three-phase circuit interrupting device must...grounded-phase, undervoltage, and ground wire monitoring protection. The...

2010-07-01

331

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

332

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

333

AC losses of a tri-axial superconducting cable with balanced three-phase current distributions

International Nuclear Information System (INIS)

High Temperature Superconducting (HTS) cables have been studied because of low loss and compactness, compared with conventional copper cables. Three-phase cables are usually composed of three single-phase concentric cables. Recently, a tri-axial cable composed of three concentric phases, has been intensively developed, because it has advantages such as reduced amount of HTS tapes, low leakage fields, low heat in leak and compactness, compared with the three single-phase cables. We analyzed the three-phase balanced current distributions in the tri-axial cable as functions of winding pitches of three concentric phase layers. We formulated the general form of AC losses in the case of the transport current and the field in different phase. We analyze AC losses of a tri-axial cable with balanced three-phase current distributions

334

Determination of two and three phase relative permeability values by using a pore network model

Energy Technology Data Exchange (ETDEWEB)

In this study, a Pore Network (PN) tool was developed in order to obtain two and three phase relative permeability values. It has been found that the observed results agree with published data. It has also been found that as contact angle increased, irreducible water saturation decreased, and oil relative permeability increased for two phase oil-water imbibition simulations. During the three phase displacement simulation by pore network simulation it was observed that water and gas relative permeabilities are only dependent on their own saturations, but oil relative permeability is dependent on its initial and own saturations in addition to water and gas saturations. It was also observed that as contact angle increased, the three phase region enlarged, and as relative permeability of oil increased, the oil isoperms became linear from concave towards the 100% oil apex. (author)

Karaman, T. [Turkish Petroleum Corp., Ankara (Turkey); Demiral, B. [METU, Ankara (Turkey). Dept. of Petroleum and Natural Gas Engineering

2004-06-15

335

Three-phase inclusions of arbitrary shape with internal uniform hydrostatic thermal stresses

We investigate the internal thermal stress field of a three-phase inclusion of arbitrary shape which is bonded to an infinite matrix through an interphase layer. The three phases have different thermoelastic constants. It is found that the internal thermal stress field induced by a uniform change in temperature can be uniform and hydrostatic within an inclusion of elliptical or hypotrochoidal shape when the thickness of the interphase layer is properly designed for given material parameters of the three-phase composite. Several examples are presented to demonstrate the solution. The thermal stress analysis of a ( Q + 2)-phase inclusion of arbitrary shape with Q ? 2 is also carried out under the assumption that all the phases except the internal inclusion share the same elastic constants. It is found that the irregular inclusion shape permitting internal uniform hydrostatic thermal stresses becomes really arbitrary if a sufficiently large number of interphase layers are added between the inclusion and the matrix.

Wang, Xu; Chen, Weiqiu

2013-08-01

336

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

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

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

339

Three-phase Single Switch Power Factor Correction Circuit with Harmonic Reduction

Directory of Open Access Journals (Sweden)

Full Text Available A harmonic injection technique, which reduces the line frequency harmonics of the single switch three-phase boost rectifier, has been implemented. In this method, a periodic voltage is injected in the control circuit to vary the duty cycle of the rectifier switch within a line cycle so that the fifth-order harmonic of the input current is reduced to meet the total harmonic distortion (THD requirement. Since the injected voltage signal, which is proportional to the inverted ac component of the rectified three-phase line-to-line input voltages is employed; the injected duty cycle variations are naturally synchronized with the three-phase line-to-neutral input voltages.

S.M. Bashi

2005-01-01

340

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

341

HIGH EFFICIENCY BRIDGELESS PWM CUK CONVERTER WITH SOFT SWITCHING TECHNIQUE

Directory of Open Access Journals (Sweden)

Full Text Available High efficiency bridgeless single-phase ac-dc PWM cuk converter with soft-switching (ZVS technique is proposed. This paper emphasizes more on the converter efficiency. The conduction losses and input current harmonics of the proposed converter is very less due to the absence of the input diode bridge and also during each switching cycle, only two semiconductor switches are present in the current path unlike other conventional Cuk converters. Soft switching (ZVStechnique is applied by using an auxiliary circuit to improve the efficiency of the proposed converter. Output voltage regulating control technique is provided to regulate the output which also ultimately improves the efficiency. Power factor is almost unity due to less input current harmonics. The circuit configuration, principle of operation, design procedure and simulation results are presented.

ANJAN KUMAR SAHOO, SARIKA KALRA, NITIN SINGH

2013-06-01

342

Soft switching PWM isolated boost converter for fuel cell application

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-07-01

343

Soft switching PWM isolated boost converter for fuel cell application

Energy Technology Data Exchange (ETDEWEB)

In this paper a new soft switching isolated boost type converter is introduced for fuel cell applications. In this converter zero voltage switching condition is achieved for the main switches and the auxiliary circuit is also soft switched. Also, the converter control circuit is simple PWM. Due to achieved soft switching condition, the converter can operate at high powers which make it suitable for fuel cell applications. Also, due to high voltage gain of the converter and isolation between input and output sources, the converter is a proper choice for the interface of fuel cell and inverters. Furthermore, the input current of the converter (current drained from the fuel cell) is almost constant since it is a boost type converter. The converter is analyzed and the simulation results presented confirm the validity of theoretical analysis. (orig.)

Rezaei, Majid [Isfahan Subsea R and D Institute (Iran, Islamic Republic of)

2010-07-01

344

Imaging phase holdup distribution of three phase flow systems using dual source gamma ray tomography

International Nuclear Information System (INIS)

Full text: Multiphase reaction and process systems are used in abundance in the chemical and biochemical industry. Tomography has been successfully employed to visualize the hydrodynamics of multiphase systems. Most of the tomography methods (gamma ray, x-ray and electrical capacitance and resistance) have been successfully implemented for two phase dynamic systems. However, a significant number of chemical and biochemical systems consists of dynamic three phases. Research effort directed towards the development of tomography techniques to image such dynamic system has met with partial successes for specific systems with applicability to limited operating conditions. A dual source tomography scanner has been developed that uses the 661 keV and 1332 keV photo peaks from the 137Cs and 60Co for imaging three phase systems. A new approach has been developed and applied that uses the polyenergetic Alternating Minimization (A-M) algorithm, developed by O'Sullivan and Benac (2007), for imaging the holdup distribution in three phases' dynamic systems. The new approach avoids the traditional post image processing approach used to determine the holdup distribution where the attenuation images of the mixed flow obtained from gamma ray photons of two different energies are used to determine the holdup of three phases. In this approach the holdup images are directly reconstructed from the gamma ray transmission data. The dual source gamma ray tomography scannThe dual source gamma ray tomography scanner and the algorithm were validated using a three phase phantom. Based in the validation, three phase holdup studies we carried out in slurry bubble column containing gas liquid and solid phases in a dynamic state using the dual energy gamma ray tomography. The key results of the holdup distribution studies in the slurry bubble column along with the validation of the dual source gamma ray tomography system would be presented and discussed

345

Current flux harmonics in no-load three-phase transformers

Energy Technology Data Exchange (ETDEWEB)

Transformers represent one source of harmonics in the power system network, because of the non linearity and the asymmetry of the three-phase ferromagnetic core used. This paper presents a general method for computing the current and flux harmonics in no-load three-phase transformers. The three-limb core and the five-limb core three-phase transformers as well the three-phase bank of three single-phase transformers are examined in the following connection of the windings: star-star, star-delta and delta-star. In particular, the analysis shows that a high third harmonic component can exist in the line currents of a no-load three-phase transformer, with three of five-limb core, having the primary winding delta-connected or star-connected with not-grounded neutral terminal, also when the supply voltage system is symmetrical. This because of the dissymetry of the non-linear magnetic circuit of the three-phase machine. Knowledge of the current harmonics is essential for the study of the pollution of the supply network; the knowledge of fluxes and their wave shapes permits the evaluation of the iron loss in operating conditions different from the rate ones and the determination of the voltage harmonics, which cause a higher insulation stress. The adopted method is general and uses the non-linear equivalent magnetic networks, which take into account both the actual electromagnetic configurations of the examined devices and their winding connections. The analysis is made by means of a general purpose simulation program on a digital computer.

Arturi, C.M. (Politecnico di Milano, Milan (Italy). Dipt. di Elettrotecnica)

1989-02-01

346

A digital input class-D audio amplifier with sixth-order PWM

A digital input class-D audio amplifier with a sixth-order pulse-width modulation (PWM) modulator is presented. This modulator moves the PWM generator into the closed sigma—delta modulator loop. The noise and distortions generated at the PWM generator module are suppressed by the high gain of the forward loop of the sigma—delta modulator. Therefore, at the output of the modulator, a very clean PWM signal is acquired for driving the power stage of the class-D amplifier. A sixth-order modulator is designed to balance the performance and the system clock speed. Fabricated in standard 0.18 ?m CMOS technology, this class-D amplifier achieves 110 dB dynamic range, 100 dB signal-to-noise rate, and 0.0056% total harmonic distortion plus noise.

Shumeng, Luo; Dongmei, Li

2013-11-01

347

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

348

Study on High Current PWM Unipolar Four Phases Driver for Stepper Motor Control

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents the study on high – current PWM, unipolar stepper motor controller/driver, are remarkable for simplicity, high – reliability, multifunctional facilities for four phases hybrid stepper motor.

Alexandru Morar

2013-01-01

349

Study on High Current PWM Unipolar Four Phases Driver for Stepper Motor Control

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the study on high – current PWM, unipolar stepper motor controller/driver, are remarkable for simplicity, high – reliability, multifunctional facilities for four phases hybrid stepper motor.

Alexandru Morar

2013-06-01

350

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.

Jensen, Bogi Bech

2012-01-01

351

Surface Effect on Three Phase Lines of Low-Ohmic Furnaces

Directory of Open Access Journals (Sweden)

Full Text Available The article another option of using numerical method of elementary conductors in surface effect three-phase supply linesfor low-ohmic furnaces. Impedance asymmetry of three-phase supply lines of different conductor profiles and various spaceconfigurations is analysed following to the author`s article published in this journal (Vol. 2/2003, No. 2, pg. 42. Options of reducingunfavourable effect of so called live and dead phase and their utilization in design and construction of mentioned lines are outlined.

Pavel Novak

2004-01-01

352

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2013-01-01

353

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

354

Fuzzy Logic Closed Loop Control of 5 level MLI Driven Three phase Induction motor

Directory of Open Access Journals (Sweden)

Full Text Available This paper deals about fuzzy logic control of closed loop controlled five level Multi Level Inverter (MLI driven three phase induction motor. Three phase Induction motor is most widely used drive in Industries, so needs proper control of speed. Induction motor is fed from five level multilevel inverter which is controlled by fuzzy logic. The closed loop consists of two loops. First inner loop is current loop and second outer loop is speed loop. The torque is varied at different times and corresponding change in speed and Total Harmonic Distortion (THD is observed. The MLI is controlled by Sinusoidal Pulse Width Modulation (SPWM Technique

Mulukutla Venkata Subramanyam

2013-02-01

355

Attractor comparison analysis for characterizing vertical upward oil—gas—water three-phase flow

We investigate the dynamic characteristics of oil—gas—water three-phase flow in terms of chaotic attractor comparison. In particular, we extract a statistic to characterize the dynamical difference in attractor probability distribution. We first take time series from Logistic chaotic system with different parameters as examples to demonstrate the effectiveness of the method. Then we use this method to investigate the experimental signals from oil—gas—water three-phase flow. The results indicate that the extracted statistic is very sensitive to the change of flow parameters and can gain a quantitatively insight into the dynamic characteristics of different flow patterns.

Zhao, Jun-Ying; Jin, Ning-De; Gao, Zhong-Ke; Du, Meng; Wang, Zhen-Ya

2014-03-01

356

TORQUE ANALYSIS OF THREE-PHASE INDUCTION MOTOR UNDER VOLTAGE UNBALANCE USING 2D FEM

Directory of Open Access Journals (Sweden)

Full Text Available Because of various techno-economic benefits, three-phase induction motors are used extensively in industry, commercial and residential applications and most of them are connected to electric power distribution system directly, thus they will be affected by voltage quality problems. An important voltage quality problem in power systems is voltage unbalance. Therefore, it is very important to studyperformance of these motors under unbalanced voltages. In this paper, Two-Dimensional Finite Element Method is employed to analyze the performance of a three-phase squirrel cage induction motor undervoltage unbalance, focusing on electromagnetic torque.

ALI EBADI,

2011-02-01

357

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

358

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Jaroslav Dudrik; Vladimír Ruš?in; Marcel Bodor; Daniel Nistor Trip; Pavol Špánik

2009-01-01

359

This paper presents a performance evaluation and a simple speed control method of an asymmetrical parameter type two-phase induction motor drive using a three-leg VSI (Voltage Source Inverter). The two-phase induction motor is adapted from an existing single-phase induction motor resulting in impedance unbalance between main and auxiliary windings. The unbalanced two-phase inverter outputs with orthogonal displacement based on a SPWM (Sinusoidal Pulse Width Modulation) method are controlled with appropriate amplitudes for improving the motor performance. Dynamic simulation of the proposed drive system is given. A simple speed controller based on a slip regulation method is designed. The overall system is implemented on a DSP (Digital Signal Processor) board. The validity of the proposed system is verified by simulation and experimental results.

Piyarat, Wekin; Kinnares, Vijit

360

DEFF Research Database (Denmark)

Unbalanced grid voltage will cause large dc-bus voltage ripple and introduce high harmonic current components on the grid side. This will severely threaten the safety of the grid-connected voltage source converter (VSC) and consequently, affect the healthy operation condition of the load. In this study, a new proportional-integral-resonant (PI-RES) controller-based, space vector modulated direct power control topology is proposed to suppress the dc-bus voltage ripple and in the same time, controlling effectively the instantaneous power of the VSC. A special ac reactive power reference component is introduced in the controller, which is necessary in order to reduce the dc-bus voltage ripple and active power harmonics at the same time. The proposed control topology is implemented in the lab. Simulation and experimental results are provided to validate its performance and the analysis presented in this study.

Xiao, Lei; Huang, Shoudao

2013-01-01

361

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

362

Three-phase scintigraphy in epicondylitis of the lateral lower humerus

Energy Technology Data Exchange (ETDEWEB)

Ten patients with tennis elbow were examined by three-phase scintigraphy, using sup(99m)Tc-MDP. In agreement with the histological findings of H. Schneider (14), there was no uptake during the perfusion and soft tissue phase. In the phase, there was focal bone uptake in one patient only.

Koppers, B.; Riel, K.

1982-08-01

363

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.)

364

Analysis of a Three Phase Induction Motor Directly from Maxwell's Equations

The torque developed in a three phase AC squirrel cage motor is usually expressed in terms of resistances and reactances of the stator, the rotor, and the motor as a whole. We use Maxwell's equations to find the torque in terms of geometrical parameters. This allows us to estimate the torque developed by a motor without knowing the details of its circuitry.

Bhattacharjee, Shayak

2011-01-01

365

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

366

On the efficiency of gas heating by a three-phase ac sliding arc plasma generator

The results of an experimental study of the operation of a three-phase single-chamber arc plasma generator with sliding arcs are presented. The efficiency and mass-average temperature values and their dependences on external parameters have been obtained. The structure of the flow in the output cross-section of the plasma generator is considered.

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

2007-11-01

367

Teachers as Learners: Studying a Three-Phased Rubric Assessment Plan.

In this study, rubrics were developed using teacher expectations, alignment with assignment objectives, and learner interests and needs. Twenty-three teachers taking master's-level coursework in gifted education learned about the flexible rubric assessment. The three-phase implementation plan took 15 weeks and allowed participants to take control…

Schultz, Robert A.

2002-01-01

368

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

369

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

370

Energy Technology Data Exchange (ETDEWEB)

National and international methodologies are presented existing for determination of the yield of industrial three phase induction motors, viewing the energy consumption reduction and assessment of possible equipment replacement. So, measurement results were analysed, conducted by five enterprises specialized on motor efficiency. Also, it is presented a case study using the described methodologies.

Ramos, Mario Cesar E.S.; Tatizawa, Hedio [Universidade de Sao Paulo (USP), SP (Brazil); Ramos, Mario Cesar Giacco [Universidade de Mogi das Cruzes (UMC), SP (Brazil)

2009-04-15

371

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

Directory of Open Access Journals (Sweden)

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

R.V. Vlasenko

2014-09-01

372

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

373

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

374

Asymmetrical Six-Phase Space Vector Pwm Scheme

Directory of Open Access Journals (Sweden)

Full Text Available Multiphase electric motors have smaller torque pulsations and are more reliable that their three-phase alternatives. However, standard electricity grids around the world are three-phase, so power inverter is needed to drive multiphase motors. Inverter is used not only to power the motor, but also to control the amplitude and frequency of the produced voltage, thus controlling motor speed and torque. Multiphase systems with odd number of phases have been widely investigated; therefore, this paper focuses on a six-phase inverter with a single neutral symmetrical load. A novel asymmetrical space vector modulation scheme is proposed and evaluated using simulations in Matlab/Simulink. Simulation results are compared to other modulation schemes. The proposed method is suitable for generating near-sinusoidal output voltages; however, it might not be suited for driving motors with sinusoidally distributed stator windings.

Tadas Lipinskis

2014-05-01

375

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

376

Existence of three-phase interlines on a cerium dioxide surface

The three-phase interline described by a statistical continuum limit (i.e. quasi-boundary) has been postulated to gain a deeper insight into the reduction of CeO2 to CeO1.940 in a LiCl-KCl eutectic melt. Fabrication of a CeO2 superstructure by a condensed-phase method provided a CeO2 (111) surface at the nanoscale, which allowed the three-phase interline to be identified given previously reported quantum confinement effects in quasi-stoichiometric CeO2 nanoparticles. Also, the CeO2 superstructure displays the same crystal lattice planes as a bulk CeO2 grain but the triply degenerate Raman-active peak of the grain is higher by a factor of ~ 2.5 with a wider full width at half maximum.

Osarinmwian, Charles

2013-01-01

377

Implementation of Single Phase Hybrid Active Power Filter for Single & Three Phase Systems

Directory of Open Access Journals (Sweden)

Full Text Available Abstract:This paper presents an implementation of hybrid active power filter for decreasing the distortions in currents in a single-phase and three phase systems. In this method, the active power filter is injecting equal but opposite current to mitigate the distortion current shape the supply current to a sinusoidal form and in phase with the supply voltage. To reduce switching stress, losses a single-switch parallel active power filter is used. for removing the high order and low order harmonics a parallel active power filter and a passive filter is connected. The passive filter uses simple LC configuration; while the parallel active filter uses a single- switch topology typically used in boost rectifier circuit. Theoretical, simulation results are presented for the single and three-phase systems with feeding non-linear loads.

V. OBUL REDDY, POOJARI VIDYA SAGAR

2013-08-01

378

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

379

Axial dispersion of the liquid phase in a three-phase Karr reciprocating plate column

Directory of Open Access Journals (Sweden)

Full Text Available The influence of the gas flow rate and vibration intensity in the presence of the solid phase (polypropylene spheres on axial mixing of the liquid phase in a three phase (gas-liquid-solid Karr reciprocating plate column (RPC was investigated. Assuming that the dispersion model of liquid flow could be used for the real situation inside the column, the dispersion coefficient of the liquid phase was determined as a function of different operating parameters. For a two-phase liquid-solid RPC the following correlation was derived: DL = 1.26(Af1.42 UL0.51 eS0.23 and a similar equation could be applied with ± 30 % confidence for the calculation of axial dispersion in the case of a three-phase RPC: DL = 1.30(Af0.47 UL0.42 UG0.03eS-0.23.

DEJAN U. SKALA

2004-07-01

380

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

International Nuclear Information System (INIS)

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

381

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

382

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

383

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.

384

Energy and mass balance in the three-phase interstellar medium

Details of the energy and mass balances are considered in the context of a three-phase interstellar medium. The rates of mass exchange between the different phases are derived based on the pressure variations created by supernova remnant expansions. It is shown that the pressure-confined warm and cold gases have stable temperatures under a variety of interstellar conditions. The three-phase quasi-static configuration is found to be a natural outcome, and both warm and cold phases generally contribute about half of the total mass density to the diffuse interstellar gas. The model is also likely to be self-regulatory in the sense that variations of the input parameters do not strongly alter the general result, which is consistent with most current observations. The consequences of extreme conditions on this model are considered, and the possible implications for interstellar medium in other galaxies are briefly discussed.

Wang, Zhong; Cowie, Lennox L.

1988-01-01

385

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

Directory of Open Access Journals (Sweden)

Full Text Available An adaptive radial basis function (RBF neural network control system for three?phase active power filter (APF is proposed to eliminate harmonics. Compensation current is generated to track command current so as to eliminate the harmonic current of non?linear load and improve the quality of the power system. The asymptotical stability of the APF system can be guaranteed with the proposed adaptive neural network strategy. The parameters of the neural network can be adaptively updated to achieve the desired tracking task. The simulation results demonstrate good performance, for example showing small current tracking error, reduced total harmonic distortion (THD, improved accuracy and strong robustness in the presence of parameters variation and nonlinear load. It is shown that the adaptive RBF neural network control system for three?phase APF gives better control than hysteresis control.

Juntao Fei

2013-05-01

386

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

387

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.

T. Salmi

2000-12-01

388

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

389

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

Directory of Open Access Journals (Sweden)

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

K. S. Sandhu

2009-08-01

390

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

391

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

392

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

393

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2006-01-01

394

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 stator and rotor curr...

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

2010-01-01

395

Digital Repository Infrastructure Vision for European Research (DRIVER)

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, Francois; Rouchon, Pierre

2008-01-01

396

Analysis of three-phase power transformer laminated magnetic core designs

Directory of Open Access Journals (Sweden)

Full Text Available Analysis and research into properties and parameters of different-type laminated magnetic cores of three-phase power transformers are conducted. Most of new laminated magnetic core designs are found to have significant shortcomings resulted from design and technological features of their manufacturing. These shortcomings cause increase in ohmic loss in the magnetic core, which eliminates advantages of the new core configurations and makes them uncompetitive as compared with the classical laminated magnetic core design.

M.I. Levin

2014-03-01

397

A three-phase free boundary problem with melting ice and dissolving gas

Digital Repository Infrastructure Vision for European Research (DRIVER)

We develop a mathematical model for a three-phase free boundary problem in one dimension that involves the interactions between gas, water and ice. The dynamics are driven by melting of the ice layer, while the pressurized gas also dissolves within the meltwater. The model incorporates a Stefan condition at the water-ice interface along with Henry's law for dissolution of gas at the gas-water interface. We employ a quasi-steady approximation for the phase temperatures and th...

Ceseri, Maurizio; Stockie, John M.

2013-01-01

398

Origin and control of instability in SCR/triac three-phase motor controllers

The energy savings and reactive power reduction functions initiated by the power factor controller (PFC) are discussed. A three-phase PFC with soft start is examined analytically and experimentally to determine how well it controls the open loop instability and other possible modes of instability. The detailed mechanism of the open loop instability is determined and shown to impose design constraints on the closed loop system. The design is shown to meet those constraints.

Dearth, J. J.

1982-08-01

399

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper deals with performance analysis and implementation of a three phase inverter fed induction motor (IM) drive system. The closed loop control scheme of the drive utilizes the Digital Phase Locked Loop (DPLL). The DPLL is safely implemented all around the well known integrated circuit DPLL 4046. An ex-perimental verification is carried out on one kw scalar controlled IM system drives for a wide range of speeds and loads appliance. This presents a simple and high performance solution f...

Ben Hamed Mouna; Sbita Lassaâd

2011-01-01

400

Analysis of three-phase rectifiers with constant-voltage loads

Digital Repository Infrastructure Vision for European Research (DRIVER)

This work presents a quantitative analysis of the operating characteristics of three-phase diode bridge rectifiers with AC-side reactance and constant-voltage loads. We focus on the case where the AC-side currents vary continuously (continuous AC-side conduction mode). This operating mode is of particular importance in alternators and generators, for example. Simple approximate expressions are derived for the line and output current characteristics as well as the input power factor. Expressio...

Caliskan, Vahe; Perreault, David J.; Kassakian, John G.; Jahns, Thomas M.

2003-01-01

401

Harmonic Wave Analysis and Suppression Research on Three-phase SPWM Inverter

Digital Repository Infrastructure Vision for European Research (DRIVER)

The output voltage of the Sinusoidal Pulse Width Modulation (SPWM) inverter contains various ultra harmonics. It increases the system’s power consumption and generates the harmonic interference. By establishing the mathematical model of the three-phase inverter and doing the FFT transformation on the output voltage, it analyses the relation between the output voltage and the combined conduction states of the inverter’s switches during one waveform cycle, it also analyzes the main pa...

Qiang Chen; Heping Liu; Hongbing Li; Hui Xie

2013-01-01

402

High Performance Speed Sensorless Control of Three-Phase Induction Motor Based on Cloud Computing

Digital Repository Infrastructure Vision for European Research (DRIVER)

Induction motor is a cast of alternating current motor where charge endures allotted to the rotor close-at-hand deputation of conductive charge. These motors are broadly applied in industrial claim due to they are arduous along with adhere no contacts. The speed controller of deltoid phase induction motor is applied to alleviate the aberration of speed. The central constructivist of this paper is to accrue the performance of speed sensorless control of three phase induction motor. To increase...

Salem, Z. M.; Abbas, M. A.

2012-01-01

403

Directory of Open Access Journals (Sweden)

Full Text Available For islanded microgrids, droop-based control concepts have been developed both in single and three-phase variants. The three-phase controllers often assume a balanced network; hence, unbalance sharing and/or mitigation remains a challenging issue. Therefore, in this paper, unbalance is considered in a three-phase islanded microgrid in which the distributed generation (DG units are operated by the voltage-based droop (VBD control. For this purpose, the VBD control, which has been developed for single-phase systems, is extended for a three-phase application and an additional control loop is added for unbalance mitigation and sharing. The method is based on an unbalance mitigation scheme by DG units in grid-connected systems, which is altered for usage in grid-forming DG units with droop control. The reaction of the DG units to unbalance is determined by the main parameter of the additional control loop, viz., the distortion damping resistance, Rd. The effect of Rd on the unbalance mitigation is studied in this paper, i.e., dependent on Rd, the DG units can be resistive for unbalance (RU or they can contribute in the weakest phase (CW. The paper shows that the RU method decreases the line losses in the system and achieves better power equalization between the DG unit’s phases. However, it leads to a larger voltage unbalance near the loads. The CW method leads to a more uneven power between the DG unit’s phases and larger line losses, but a better voltage quality near the load. However, it can negatively affect the stability of the system. In microgrids with multiple DG units, the distortion damping resistance is set such that the unbalanced load can be shared between multiple DG units in an actively controlled manner rather than being determined by the microgrid configuration solely. The unit with the lowest distortion damping resistance provides relatively more of the unbalanced currents.

Tine L. Vandoorn

2013-12-01

404

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

405

PMU based Detection of Imbalance in Three-Phase Power Systems

Digital Repository Infrastructure Vision for European Research (DRIVER)

The problem of imbalance detection in a three-phase power system using a phasor measurement unit (PMU) is considered. A general model for the zero, positive, and negative sequences from a PMU measurement at off-nominal frequencies is presented and a hypothesis testing framework is formulated. The new formulation takes into account the fact that minor degree of imbalance in the system is acceptable and does not indicate subsequent interruptions, failures, or degradation of ph...

Routtenberg, Tirza; Xie, Yao; Willett, Rebecca M.; Tong, Lang

2014-01-01

406

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

Directory of Open Access Journals (Sweden)

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

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

2013-07-01

407

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

408

Design of materials with extreme thermal expansion using a three-phase topology optimization method

DEFF Research Database (Denmark)

Composites with extremal or unusual thermal expansion coefficients are designed using a three-phase topology optimization method. The composites are made of two different material phases and a void phase. The topology optimization method consists in finding the distribution of material phases that optimizes an objective function (e.g. thermoelastic properties) subject to certain constraints, such as elastic symmetry or volume fractions of the constituent phases, within a periodic base cell. The effective properties of the material structures are found using the numerical homogenization method based on a finite-element discretization of the base cell. The optimization problem is solved using sequential linear programming. To benchmark the design method we first consider two-phase designs. Our optimal two-phase microstructures are in fine agreement with rigorous bounds and the so-called Vigdergauz microstructures that realize the bounds. For three phases, the optimal microstructures are also compared with new rigorous bounds and again it is shown that the method yields designed materials with thermoelastic properties that are close to the bounds. The three-phase design method is illustrated by designing materials having maximum directional thermal expansion (thermal actuators), zero isotropic thermal expansion, and negative isotropic thermal expansion. It is shown that materials with effective negative thermal expansion coefficients can be obtained by mixing two phases with positive thermal expansion coefficients and void. (C) 1997 Elsevier Science Ltd.

Sigmund, Ole

1997-01-01

409

PWM Technique to Overcome the Effect of High PAPR in Wireless Systems

Directory of Open Access Journals (Sweden)

Full Text Available Many current communication systems suffer from perf ormance degradation due to the high sensitivity to high power peaks especially in the nonlinear device s. The author introduces a new concept based on the Pulse Width Modulation (PWM, namely MIMO-OFDM syst em based PWM (MO-PWM to overcome this deficiency. Here, the peak-to-average power ratio ( PAPR problem in Orthogonal Frequency Division Multiplexing (OFDM technique is used as a criterio n to check the validity of the proposed work. Moreover, the proposed system work has been impleme nted over Field Programmable Gate Array (FPGA, which is designed to characterize both of the compl exity and the speed issues. The systems performance based MO-PWM and validity h ave been checked based on a numerical analysis and a conducted simulation. The simulation results show that the MO-PWM can clearly reduce the PAPR values nevertheless the used OFDM systems’ specific ations, and gives a promising results over some techniques found in the literature, such as clippin g, SLM and PTS under same bandwidth occupancy and system’s specifications.

Omar Daoud

2014-07-01

410

Half bridge ZVS DC-DC converter with DCS PWM active clamp technique

Directory of Open Access Journals (Sweden)

Full Text Available

Half bridge (HB dc–dc converter is an attractive topology for middle power level applications owing to its simplicity. This paper presents a new control scheme, to be known as duty-cycle shifted PWM (DCS PWM control, is proposed and applied to the conventional HB dc–dc converters to achieve ZVS for one of the two switches without adding extra components and without adding asymmetric penalties of the complementary control. The concept of this new control scheme is shifting one of the two symmetric PWM driving signals close to the other, such that ZVS may be achieved for the lagging switch due to the shortened resonant interval. Moreover, based on the DCS PWM control, an active clamp branch comprising an auxiliary switch and a diode is added across the isolation transformer primary winding in the half bridge converter to achieve ZVS for the other main switch by utilizing energy stored in the transformer leakage inductance. Moreover, the auxiliary switch also operates at ZVS and ZCS conditions. In addition, the proposed topology with DCS PWM control eliminates the ringing resulting from the oscillation between the transformer leakage inductance and the switches junction capacitances during the off-time period. Therefore, the proposed converter has a potential to operate at higher efficiencies and switching frequencies.

JANAPATI SIVAVARA PRASAD

2012-10-01

411

Investigation of the effects of PWM parameters on ionic polymer metal composite actuators

The effects of the PWM excitation signal parameters, such as frequency and magnitude, on the Nafion-based ionic polymer metal composite (IPMC) actuator response were found out. The first set of experiments was designed to observe the actuator response when the actuators were biased with constant DC voltages. These experimental results were exploited to build an experimental data based dynamic model. The model and these results were also used as references to evaluate the experimental results in the proceeding experiments. The second set of experiments was designed to observe the actuator response when the DC square wave signals at different frequencies (0 to 1000 Hz) were applied. The third set of experiments was designed to observe the actuator response when the PWM signals at different magnitudes (6, 8 and 10 V) were applied. It is observed that back relaxation reduces with increasing frequency, but after a certain frequency value, it remains approximately constant. It is seen that the input output relationship of the actuators are linear only for a range of PWM signal magnitudes. The observations in both the PWM frequency and the magnitude experiments indicated that the performance of the Nafion-based IPMC actuator could be improved by selecting a magnitude of PWM signals between 6-8 Volts and by selecting a frequency between 400-1000 Hz.<