Phase PWM Research Articles

A nonlinear adaptive backstepping approach applied to a three phase PWM AC–DC converter feeding induction heating

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

Frequency Domain Based Repetitive Control of Three Phase Boost PWM Rectifier Under Distorted Supply Voltage Conditions

This paper presents a digital plug-in frequency domain based repetitive control scheme for minimizing the even order harmonics at the output dc link voltage and odd order harmonics in the line currents under the distorted and unbalanced supply voltage conditions. The proposed current controller consists of a conventional PI controller and a frequency domain based plug-in repetitive controller. Based on the mathematical model of the three-phase PWM boost rectifier under the generalized supply voltage conditions, the control task is divided into: (a)dc-link voltage harmonics control and (b)line side current harmonics control. The plug-in repetitive controller is designed to achieve line side currents with low THD for the three phase PWM boost rectifier. The repetitive control learning algorithm is designed in frequency domain instead of commonly used time domain and provides the flexibility of choosing different learning gains and phase delay compensations individually for each harmonic component. The experimental test results obtained from a 1.6 kVA laboratory based PWM rectifier confirm that the THD of the line side current can be reduced from 21.09% to 4.12% with the insertion of the plug-in frequency domain based repetitive controller.

2단 3상 PWM AC/DC 컨버터를 이용한 동기발전기 여자제어시스템

동기발전기의 출력전압은 여자 시스템의 계자 전류 제어에 의해 일정하게 유지된다. 현재 대부분의 발전기 여자기의 여자전류제어를 위해 사용되는 AVR 시스템의 AC/DC 컨버터 부는 출력전압 제어가 가능한 위상제어 컨버터나 출력전압을 제어할 수 없는 다이오드 정류기와 DC/DC 컨버터를 결합하여 사용하고 있다. AC/DC 전력 변환장치로서 위상제어 컨버터나 출력전압을 제어할 수 없는 다이오드 정류기의 경우, AVR 시스템의 전력을 공급하는 모선의 역률저하 및 저차 고조파 발생의 문제점을 야기 시키게 된다. 본 논문에서는 동기발전기의 여자 전류 제어를 위해 사용되는 AVR 시스템 설계에 있어 단위역률 동작이 가능한 Boost형 AC/DC 컨버터와 모선의 부하변동에 속응성 있게 동작할 수 있는 전류 제어형 Buck 컨버터를 결합한 2단 3상 PWM AC/DC 컨버터에 대해 연구하였다. 제안된 AC/DC 컨버터를 시뮬레이션 한 결과 Boost 컨버터의 경우 단위 역률 동작 및 출력 DC전압의 Boost 동작이 원할히 이루어졌으며, Buck 컨버터의 경우 다른 위상제어 컨버터에 비해 응답시간이 개선되었음을 알 수 있었다.

Discrete‐time model following control of inverter with rectifier load

AbstractElectronic apparatus, such as a computer, are a capacitor input type rectifier load for the power supply. The rectifier load causes distortions of the power source voltage waveform. Copyright © 2004 Wiley Periodicals, Inc.This paper describes the output voltage characteristic of the single phase PWM inverter controlled by a discrete‐time model following method and connected to a rectifier load. First, the rectifier load model of a discrete‐time system is considered. Next, the discrete‐time model following control system used for this load is described. Then, simulation and experimental results are examined. The simulation results show that this method has robustness to the load change. The experimental system consists of an inverter controlled by a digital signal processor (DSP) and a rectifier load. Experimental results confirmed the validity of the simulation result. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(2): 72–81, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20375

Novel control scheme for 3-phase PWM current-source converters under unbalanced source voltage conditions

Under unbalanced source voltage supply, considerable output second harmonics and input low-order harmonics in 3-phase PWM current-source converters (PWM-CSC) are generated. This paper proposes a new deadbeat controller based on compensation for unbalanced source voltage and current. With the proposed scheme, the second harmonics of the output current are eliminated and low-order harmonics of the source current are reduced effectively. Simulation and experimental results confirmed the feasibility of the proposed method.

整流器負荷を有するインバータの離散時間モデル追従制御

Electronic apparatus, such as a computer, are a capacitor input type rectifier load for the power supply. The rectifier load causes distortions of the power source voltage waveform. Copyright © 2004 Wiley Periodicals, Inc. This paper describes the output voltage characteristic of the single phase PWM inverter controlled by a discrete-time model following method and connected to a rectifier load. First, the rectifier load model of a discrete-time system is considered. Next, the discrete-time model following control system used for this load is described. Then, simulation and experimental results are examined. The simulation results show that this method has robustness to the load change. The experimental system consists of an inverter controlled by a digital signal processor (DSP) and a rectifier load. Experimental results confirmed the validity of the simulation result. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(2): 72–81, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20375

고조파 저감 능력을 가진 직류전철 회생인버터 시스템

본 논문에서는 전철시스템의 변전소에서 직류모선에 발생하는 잉여분의 직류전력을 교류전원 측으로 회생시킬 수 있는 직류전력 회생시스템을 제안한다. 제안된 직류 전철용 회생인버터 시스템은 인버터와 능동전력필터로 사용 할 수 있다. 회생인버터 모드에서는 전철의 감속에 의해 회생되는 에너지를 재사용 할 수 있으며, 능동전력필터 모드에서는 변전소의 정류기에 의해 발생되는 고조파 왜곡을 보상하기 위해 사용할 수 있다.<br/> 전력용량과 스위칭 손실을 고려하여 시스템은 3상 PWM 인버터를 기반으로 설계되며 병렬인버터, 출력변압기와 LCL필터로 구성된다.

Effective Improvement of DC Busline Voltage Utilization Factor in Two Switch-Auxiliary Quasi-Resonant DC Link Snubber Assisted Three Phase Voltage Source Type Soft-Switching PWM Inverter

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.

A Predictive Instantaneous Current Control Method Taking into Consideration AC Side LC Filters in Three Phase PWM Voltage-Source Rectifier

In this paper, the authors will propose a new predictive instantaneous current control method taking into account AC side LC filters in three phase PWM voltage-source rectifiers. This method is based on predeictive-instantaneous-current control, so that the control structure can be very simple. The effectiveness of the proposed method is confirmed by means of computer simulations.

The AC Motor Rotational Speed Control with the Programmable Dynamics

The digital control of the AC motor enables the programmable dynamics of the rotation speed transient. There are two problems - motor control and measurement of the instant rotor angle (connected with the rotational speed calculation). It is necessity to check if the controlled motor follows the assigned curve of the motor voltage/current supply frequency and amplitude. The only solution in the high power supply range is to use the PWM waveforms. The presented multi-package system enables 3-phase motor PWM U/f control and the measurement of the instant rotor angle together with the rotational speed. The PWM generator enables the programmable dynamics of the motor rotation start and the “soft” change of the rotational speed between 2 steady values. The presented controller can operate as a part of the whole complex DMC system or in the stand-alone mode, can receive orders using RS bus or by mean of the system bus or from the local keyboard.

Synthesis of different synchronous modulators for high power three-phase/single-phase PWM converters

In this paper, the instantaneous space vector method is presented as synthesis tool for the determination of the sequential command of a three phase/single phase PWM converter which can operate as an inverter or a rectifier, with a current or a voltage DC source. Though the PWM patterns described here, satisfy criteria of symmetry, different possibilities are proposed and their spectral behaviour are compared. Considering a high power application, the ON minimal conduction time of the switches is taken into account. This comparison brings out a solution which includes many advantages.

A Method of a Single Phase PWM for a Utility-connected Power Supply in Photovoltaic Power Generation Systems

We propose a method of a sigle phase PWM for a utility-connected power supply in photovoltaic power generation systems. In this paper, the PWM is derived from camparing levels of signal waves with ones of carrier waves which have bipolar swing different from unipolar one in the conventional PWM, and shifting phase a little at exery on-off time. We can expect that array voltage needed is reduced by about 15% and harmonics content contained in output voltage is reduced by about 24% in this PWM in comparison with the conventional with equal output voltage.

Suppression for Transient Oscillation of Input Voltage and Current in Current-Source Three-Phase PWM AC/DC Converter.

As a high performance current-source three-phase AC/DC converter, the PWM control is promising to achieve a unity power factor and to improve the input current distortion. In contrast to the voltage-source converter, the LC filter connected between the source and the converter may cause a LC resonance both in steady and transient states. Many reports have been published to improve the current distortion in steady state and to suppress the current oscillation in transient state of the current-source PWM converter.The paper gives an analysis of voltage oscillation of the filter voltage and proposes the suppression approach for the current-source three phase PWM AC/DC converter. The effectiveness of the proposed approach has been verified by experiments.

A Method of Single Phase PWM for an Independent Power Supply in Photovoltaic Power Generation Systems.

A Method of Single Phase PWM for an Independent Power Supply in Photovoltaic Power Generation Systems.

Resonant link bidirectional power converter. II. Application to bidirectional AC motor drive without electrolytic capacitor

This paper proposes a new power converter which consists of two identical 3-phase PWM modulators and a novel resonant circuit. A new control strategy is integrated to realize the bidirectional power converter without an electrolytic link capacitor. The power flow between converters is bidirectional and the regenerative braking is inherent. The source side currents maintain sinusoidal waveforms with a unity power factor. It is observed in the experiment that by balancing the active power between the source and load side, the voltage across a small ceramic link capacitor can be maintained within a small deviation from the reference. Simulation results and experimental results are presented to verify the operational principles. >

Minimisation of interharmonic currents from a current source AC drive by means of a selective DC side active filter

Current source AC drives draw a current waveform from the supply which is both distorted and unsteady. The frequency spectrum of the supply current contains harmonic components and interharmonic components which change frequency with the speed of the output motor. The increasing number of large current source variable frequency AC motor drives in use on power systems is causing concern over the interharmonic current distortion produced by the drives. If the interharmonic currents are excessive and compensation is required, it is difficult to achieve attenuation of these components with conventional passive filters. This paper describes how a single phase PWM current source inverter connected in the DC link of a current source drive may be used to filter out AC side current interharmonic components. A prototype filter has been built and tested on a low power model of a variable speed synchronous motor drive system. Results show clearly that a significant reduction in the interharmonic current magnitude can be achieved using the DC side active filter. The results of computer simulations show that the rating of the active filter should be approximately 1% of the drive rating. Hence, the active filter may be realised using commonly available power semiconductor devices.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Multi-functional PWM Inverter for Solar Power Generation System.

We propose a new multi-functional single phase PWM inverter for solar power generation system. In this case, it is important to construct the main circuit with simple circuit configuration and control. The proposed single phase inverter with an AC line switch can be constructed only by a three phase inverter module. The functions of the inverter are as follows; 1) an inverter to send the solar cell energy to the utility line, 2) a power line conditioner with an active filter and a reactive power compensator and line voltage controller at the line connecting mode. and 3) an uninterrupted power supply at the line power failer and so on. These are desirable from view points of improving the cost performances of the system.In this paper, the proposed control circuit and the principle of operation, the control functions and their control characteristics are described. Then some simulation results of the system with many functions are shown. The feasibility of the inverter system are verified by experimental results.

Multiple Single Phase PWM Inverter by means of Combination Control.

In this paper, we propose a new multi-level inverter with simple circuit configuration and control. The inverter is composed of a series connection of individual single phase inverters. The number of the output voltage levels depends on the number of the individual inverters in series and their output voltage level. The switching devices in the new circuit configuration can be reduced by using a common switching-leg for the individual inverters. In this inverter circuit, the number of the levels is equal to 2m-1 or 2m where m is the number of switching-legs used. In the paper, a 15 levels inverter using four switching legs (m=4) is introduced. If the number of voltage levels is increased, smoother sinusoidal waveforms can be obtained directly and it is possible to control the output voltage almost continuously from zero to maximum without generating high voltage step changes as pulse width modulation techniques.The control principle, the circuit configuration and the characteristics of the output voltage control are discussed. The feasibility of the circuit is demonstrated by simulation and experimental results.

Multi-functional High Quality Single Phase PWM Controlled Power Supply.

Recently, many apparatus have been used for residential applications by the remarkable progress of the power electronics technology. So, harmonics and power factor problems have become important. This paper proposes the multi-functional high quality single phase power converter with a simple circuit configuration using a power module for three phase inverters. The basic operation of the proposed power converter is almost the same as the double converter by the inverter and the converter circuit. Many functions about the AC power line, the DC power source line with loads and the AC output load can be obtained by using the proposed circuit configuration. The converter also has the useful functions of the direct connecting the AC load to the AC power line and the line interrupting at the AC power line failer.In this paper, I describe the circuit configuration, the control principle, the obtainable functions and the control methods. Then I confirm the feasibility of the system by the simulations and the experiments.

Quasi-parallel resonant DC link inverterwith improved PWM capability

A quasi-parallel resonant DC-link (QPRDCL) circuit with improved PWM capability is proposed for the zero voltage switching (ZVS) three phase PWM inverter. The circuit has minimum voltage stresses and improved PWM capability due to the flexible selectability of the on/off instants of the resonant link.