A unity power factor PWM rectifier with DC ripple compensation

This paper presents a new topology for a pulsewidth modulation (PWM) rectifier which achieves unity power factor on the AC supply side and ripple reduction on the DC output side. The main circuit of this rectifier consists of a conventional PWM rectifier and a pair of additional switches. The switches and PWM rectifier are controlled such that the ripple current on the DC line is reduced, and unity power factor is achieved on the AC line. As a result, this circuit does not require a large DC capacitor or a passive LC resonant circuit. Furthermore, control of the additional switches and PWM rectifier requires only a simple control circuit. The effectiveness of this circuit was confirmed by experiments and analysis. The rectifier is useful for uninterruptible power systems (UPSs) and DC power supplies, especially for cases in which batteries are connected to the DC line     

基于电驱动钻机的交流电子负载的研究

基于现代电力电子技术,深入研究能量回馈式的交流电子负载的主电路结构和控制策略。主电路采用AC／DC／AC拓扑,并选用电压型PWM整流器构成其输入、输出变流器。提出了一种基于DSP的交流电子负载的控制策略。     

Control of Single-Phase-to-Three-Phase AC/DC/AC PWM Converters for Induction Motor Drives

This paper proposes a novel control scheme of single-phase-to-three-phase pulsewidth-modulation (PWM) converters for low-power three-phase induction motor drives, where a single-phase half-bridge PWM rectifier and a two-leg inverter are used. With this converter topology, the number of switching devices is reduced to six from ten in the case of full-bridge rectifier and three-leg inverter systems. In addition, the source voltage sensor is eliminated with a state observer, which controls the deviation between the model current and the system current to be zero. A simple scalar voltage modulation method is used for a two-leg inverter, and a new technique to eliminate the effect of the dc-link voltage ripple on the inverter output current is proposed. Although the converter topology itself is of lower cost than the conventional one, it retains the same functions such as sinusoidal input current, unity power factor, dc-link voltage control, bidirectional power flow, and variable-voltage and variable-frequency output voltage. The experimental results for the V/f control of 3-hp induction motor drives controlled by a digital signal processor TMS320C31 chip have verified the effectiveness of the proposed scheme     

Analysis,design and implementation of an interleaved three-level PWM DC/DC ZVS converter

This paper presents a new parallel three-level soft switching pulse-width modulation (PWM) converter. The proposed converter has two circuit cells operated by the interleaved PWM modulation. Thus, the ripple currents at input and output sides are reduced. Each circuit cell has two three-level zero voltage switching circuits sharing the same power switches. Therefore, the current and power rating of the secondary side components are reduced. Current double rectifier topology is selected on the secondary side to decrease output ripple current. The main advantages of the proposed converter are soft switching of power switches, low ripple current on the output side and low-voltage rating of power switches for medium-power applications. Finally, the performance of the proposed converter is verified by experiments with 1 kW prototype circuit.     

DC-side shunt-active power filter for phase-controlled magnet-loadpower supplies

Phase-controlled thyristor rectifiers are still the preferred choice in high-power AC/DC converters. This paper shows that their steady-state and dynamic performance can be greatly enhanced for applications requiring high-precision fast-response performance by means of a hybrid structure using a shunt pulse-width modulation (PWM) active filter. In this hybrid structure, the rectifier is designed to handle the bulk of the output power, whereas the PWM converter is only used for harmonic cancellation and current-error compensation under transient conditions. This results in a small power rating for the shunt-active filter. A suitable control scheme is proposed and implemented in this paper for the rectifier and PWM converter. Experimental results are provided to validate the proposed concept     

A novel ZVS DC/DC converter for high power applications

This paper presents a novel zero voltage switch (ZVS) pulse-width modulation (PWM) DC/DC converter for high power, high output voltage applications. By using two active switches in the secondary side of a transformer, the proposed converter achieves not only ZVS of the active switches in the entire load ranges but also soft commutation of the output rectifier diodes. The proposed topology has simple structure and control strategy. Simulation results and experimental results of a 2.8 kW 200 kHz DC/DC converter are presented.     

A multilevel buck converter based rectifier with sinusoidal inputs and unity power factor for medium voltage (4160-7200 V) applications

A novel rectifier topology for high power (0.5 to 10 MVA) current source based AC motor drives is proposed. This rectifier is composed of a multi-winding transformer, a multi-level diode rectifier and a modified multi-level buck converter. The rectifier produces near unity input power factor and sinusoidal input current under any operating conditions. In addition, the proposed rectifier features reliable operation and low manufacturing cost. In this paper, the operating principle of the proposed rectifier is introduced. A number of design issues are investigated, which include PWM switching patterns, input power factor and line current harmonic distortion. Some design considerations such as the effect of the line inductance discrepancy on system performance are addressed. Experiments on a 5 kVA/208V four-level prototype are carried out for verification.     

A bidirectional and isolated three-phase rectifier with soft-switching operation

A bidirectional-power-flow three-phase rectifier with high-frequency isolation and all-digital control, based on the matrix converter topology, is analyzed in this paper. The selected topology consists of a bidirectional three-phase-to-single-phase reduced matrix converter with power-factor correction and a bidirectional active rectifier. The inclusion of the isolation transformer at the switching frequency permits the reduction of volume and weight. By synchronizing the commutation of both converters and adding a saturable inductor and a blocking capacitor it is possible to achieve soft commutation for most of the semiconductor elements. An all-digital control based on a digital-signal-processor and a field-programmable gate array was used to implement space-vector modulation and output current regulation. This power converter is intended to feed the low-energy correction magnet of a particle accelerator. Experimental results of a 1.5-kW 20-kHz prototype are presented to illustrate the performance of the proposed topology.     

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

This paper describes the conception and analysis of a unidirectional hybrid three-phase rectifier suitable for medium- and high-power applications. The rectifier is composed of a single-switch diode bridge boost-type rectifier in parallel with a pulsewidth modulation (PWM) three-phase unidirectional boost rectifier. The objective is to obtain a structure capable of providing sinusoidal input currents with low harmonic distortion and dc output voltage regulation. The diode rectifier operates at low frequency and has a higher output power rating. Therefore, the PWM unidirectional rectifier is designed to operate with a small power rating and at a high switching frequency. The total harmonic distortion of the proposed structure varies between 0% and 32%, depending only on the amount of power processed by the PWM three-phase unidirectional rectifier. The rectifier topology conception, principle of operation, control scheme, and simulation and experimental results of a 20-kW laboratory prototype are also presented in this paper.     

基于PWM整流器的高效电动汽车充电机设计

介绍一种用于电动汽车电池充电机的设计实现方法.为满足高功率因数和高效的要求,采用三相PWM整流器和移相全桥变换器两级变换模式.前者基于空间电压矢量PWM直接功率控制（DPC）,实现单位功率因数;后者基于零电压零电流（ZvZCS）控制,实现高效的电能变换.以该方法设计的8 kW的充电机在大部分充电过程中,效率高于84％,输入功率因数高于99.3％.     

A New Control Method for Input–Output Harmonic Elimination of the PWM Boost-Type Rectifier Under Extreme Unbalanced Operating Conditions

Under severe fault conditions in the distribution system, not only input voltages but also input impedances must be considered as unbalanced. This paper presents a new control method for input–output harmonic elimination of the pulsewidth-modulation (PWM) boost-type rectifier under conditions of both unbalanced input voltages and unbalanced input impedances. The range of imbalance in both input voltages and input impedances, for which the proposed method is valid, is analyzed in detail. An analytical approach for complete harmonic elimination shows that PWM boost-type rectifier can operate at unity power factor under extremely unbalanced operating conditions resulting in a smooth (constant) power flow from ac to dc side. Based on the analyses in open-loop configuration, a feedforward control method is proposed. Elimination of harmonics at ac and dc side of the converter affects the cost of dc link capacitor and ac side filter. The proposed method is very useful when the PWM boost-type rectifier is subject to extreme imbalance due to severe fault conditions in the power system. In addition, by using the proposed method, the PWM boost-type rectifier can be operated from the single-phase supply in cases where three-phase source is not available. Simulation results show excellent response and stable operation of the PWM boost-type rectifier under the proposed control algorithm. Experimental and simulation results are in excellent agreement.      

Reduced-parts-count multilevel rectifiers

Multilevel power converters have gained much attention in recent years due to their high power quality, low switching losses, and high-voltage capability. These advantages make the multilevel converter a candidate topology for the next generation of naval ship prolusion systems. The primary disadvantage of these systems is the large number of semiconductors involved. This paper presents a reduced-parts-count rectifier which is well suited for naval rectifier applications where bidirectional power flow is not required. The proposed converter is analyzed and experimentally verified on an 18-kW four-level rectifier/inverter system.     

基于双向PWM变换器的微燃机发电系统起动／发电控制研究

针对微型燃气轮机（微燃机）发电系统的特点,建立了以电压型双向脉宽调制（PwM）变换器为功率变换装置的起动／发电控制模型。微型燃气轮机发电系统起动时,采用矢量控制;发电运行时,采用电压外环电流内环的双环PWM整流控制。仿真实验结果表明：起动时,高速永磁同步电机（PMSG）采用矢量控制比速度开环控制性能更优,减少了起动时间,满足快速起动的要求;发电运行时,与二极管整流相比,PWM整流能使交流侧电流跟踪发电机的感应电动势,功率因数约为1,降低了发电机侧的电流谐波,即减少了谐波热。同时保证了发电机在一定宽速范围内,输出直流电压稳定,并且在起动一发电过渡转换过程中,直流母线电压降落后,快速恢复为稳定值,满足平滑转换的要求。     

Analysis of a ripple-free input-current boost converter withdiscontinuous conduction characteristics

Coupled inductor techniques supply a method to reduce the power converter size and weight and achieve ripple-free current. The boost power converter is a very popular topology in industry. However, the input-current ripple hinders efforts to meet electromagnetic interference (EMI) requirements. In particular, the input current becomes discontinuous and pulsating when the conventional boost power converter operates in the discontinuous inductor-current mode. This paper describes a boost power converter which has the same discontinuous properties as the conventional boost power converter. However, the proposed boost topology has continuous or ripple-free input current when it operates with discontinuous inductor-current. The proposed topology is compared with traditional converter topologies, such as the Sepic and Cuk power converters. Simulation results are presented. The prototype is built to demonstrate the theoretical prediction. The proposed boost topology is simple, with straightforward control [the same as pulse-width modulation (PWM)]     

Low-harmonic GTO converter for fundamental power factorcompensation

A low-harmonic GTO (gate turn-off) thyristor AC-to-DC converter with line current lead-lag phase shift control ability is proposed and analyzed. The converter can be used either as a low-harmonic GTO-controlled rectifier or a fundamental input power factor compensator in a power supply system. The effect of PWM (pulse width modulation) current phase number on the harmonic contents and converter output voltage control range is investigated. Lower order input current harmonics are eliminated over a wide range, using a specially designed PWM current pattern. The effect of the PWM current pulse number on the power factor compensation characteristic is investigated     

Regulation of a PWM rectifier in the unbalanced network state usinga generalized model

This study concerns the modeling and control of a pulse-width-modulated (PWM) rectifier in the case of network variations. The aim is to limit and stabilize variations of DC output voltage and line currents in such circumstances. Network variations can result in costly damage to power converters and their loads but a power converter such as the PWM rectifier, using cascade digital control, offers many capabilities to stabilize the system with optimized control. A generalized model of the PWM rectifier is first presented using the Clarke notation in order to separate the positive and negative sequences. The model is also extended to the harmonics. The cases of harmonic disturbance and an unbalanced network are then analyzed and an optimized regulation is presented for the latter case, validating the generalized model. Experimental results are proposed. The line current compensation loop method coupled with identification of network parameters offers a good solution to stabilize the PWM rectifier in an unbalanced network     

Novel reduced-order small-signal model of a three-phase PWMrectifier and its application in control design and system analysis

A reduced-order (RO) small-signal model of three-phase pulse-width-modulation (PWM) rectifiers is proposed. By combining the PWM switch model and equivalent multimodule model techniques in DC-DC converters, a three-phase rectifier can be modeled as a DC-DC converter with equivalent power capability and small-signal characteristics. This model reduces the system order to two and greatly simplifies the control design and system analysis of three-phase converters. In this paper, the proposed model is also used for control design and for system interaction analysis on the three-phase interface of a boost rectifier. The RO model is verified with the d-q model, switching-model simulation, and experimental results     

三电平PWM整流器双闭环控制系统研究

本文对三电平PWM整流器的拓扑结构进行了分析,结合三电平PWM整流器的数学模型,提出了一种固定开关频率的控制方法。采用功率、电流的双闭环策略通过SVPWM对系统进行控制。该方法使用MATLAB/SIMULINK软件仿真,结果表明,该控制方法能保证中点电位平衡、网侧电流谐波小,具有良好的动、静态性能,实现了单位功率因数运行,通过样机实验,验证了所提方法的正确性和可行性。     

A Systematic Topology Evaluation Methodology for High-Density Three-Phase PWM AC-AC Converters

This paper presents a systematic evaluation approach of three-phase pulsewidth-modulated (PWM) ac–ac converter topologies for high-density applications. All major components and subsystems in a converter are considered and the interdependence of all the constraints and design parameters is systematically studied. The key design parameters, including switching frequency, modulation scheme, and passive values, are selected by considering their impacts on loss, harmonics, electromagnetic interference (EMI), control dynamics and stability, and protection. The component selection criteria as well as the physical design procedures are developed from the high-density standpoint. The concept of using the same inductor for harmonic suppression and EMI filtering is introduced in the design. With the proposed methodology, four converter topologies, a back-to-back voltage source converter (BTB-VSC), a nonregenerative three-level boost (Vienna-type) rectifier plus voltage source inverter (NTR-VSI), a back-to-back current source converter (BTB-CSC), and a 12-switch matrix converter, are analyzed and compared for high specific power using SiC devices. The evaluation results show that with the conditions specified in this paper, BTB-VSC and NTR-VSI have considerably lower loss, resulting in higher specific power than BTB-CSC and the matrix converter. The proposed methodology can be applied to other topologies with different comparison metrics and can be a useful tool for high-density topology selection.      

Time-averaged behaviour of single and dual flying capacitor converters

The Single Flying Capacitor Converter (SFCC) and Dual Flying Capacitor Converter (DFCC) are two-quadrant power supplies for energy storage and transfer systems. They have applications in nuclear research and pulsed power systems in which superconductive coils are used. In this paper analytical expressions for the time-averaged behaviours of SFCC and DFCC are derived by using averaging technique. Because large superconductive magnet coils are used, time constants of the switched circuits are large enough compared to the switching period. Therefore, an averaged PWM switch equivalent circuit is substituted into the original converter circuits to find the averaged system equations. With this new insight in the averaged dynamics, their design and control can be optimized. Although DFCC has less coil current ripple compared to SFCC, the analysis will show that the averaged behaviours of both converters are the same.