PWM整流的电机试验变频电源系统的研究

介绍了一种新型电机试验变频电源,可以满足电压等级在1200V以下,功率等级在100k W以下的异步电机、变频电机等电机的出厂试验、型式试验的需求。采用PWM整流,母线电压可调的直流环节,逆变环节采用两套PWM逆变器对被试电机及陪试电机进行控制,由于后级未使用变压器,可大大节省空间,减小体积,同时电机做叠频试验时,能保持直流母线电压的稳定,再生能量及时回馈电网,减少电容的使用量。     

一种具有能量回馈功能的级联型高压变频器的仿真研究

本文采用成熟的三相PWM整流技术,通过改造级联型高压变频器单个功率单元的整流部分,对直流母线电容电压进行闭环控制来稳定功率单元直流母线电容上的电压,实现能量回馈。这种方法不仅解决了一般的级联型高压变频器能量不能回馈,单个功率单元直流母线电容电压不稳的问题,而且还能使网侧的功率因数为1,使级联型高压变频器成为真正的绿色变频器。     

一种具有能量回馈功能的级联型高压变频器的仿真研究

本文采用成熟的三相四象限PWM整流技术,通过改造级联型高压变频器单个功率单元的整流部分,对直流母线电容电压进行闭环控制来稳定功率单元直流母线电容上的电压,实现能量回馈。这种方法不仅解决了一般的级联型高压变频器能量不能回馈,单个功率单元直流母线电容电压不稳的问题,而且还能、使网侧的功率因素为1,使级联型高压变频器成为真正的绿包变频器。     

变频器在通用大容量电机试验系统的应用

本文采用公共直流母线方式的变频器和电功率封闭技术来完成大容量交流电机的型式试验和出厂试验,被试电机涵括高低压同步发电机、异步电机、双馈电机。试验系统的电源机组和回馈机组采用共直流母线变频器驱动,组成电功率闭环,实现电能循环,达到较好的节能效果：有源整流实现可控直流母线电压,网侧高功率因数、低谐波、制动能量回馈。系统在工程应用中取得优良效果。     

变频电源在电机试验中的应用

针对电机出厂试验和型式试验,提出一种双逆变器共直流母线的能量回馈型变频电源试验系统。该系统经过对电网电压整流和逆变之后,实现电压可调和频率可调的电机试验电源,取代传统的电动机-发电机组试验设备。设计中被试电机和陪试电机分别由两组不同的逆变器驱动,两组逆变器共直流母线连接,在电机试验时实现无功补偿和对拖试验时实现能量的回馈,具有精度高,节约能源,操作方便等优点。     

特种变频电源叠频法在电机温升试验中的应用

简述了叠频法电机温升试验的基本原理,建立了采用四象限变频电源并联的电机试验平台,通过仿真软件Matl ab对变频电源叠频输出进行仿真,并进行了电机温升试验。仿真与试验结果表明,用变频电源进行叠频试验简便准确,并联结构提高了变频系统容量,且运行安全可靠。     

双级矩阵变换器式同步电机驱动研究

传统的同步电机电源通常采用三相交流电通过三相不控整流模块转换成直流电,然后再经过变频器进行转换成驱动电机的交流电。这种模式下通常需要直流侧的大电容进行滤波,同时电网的电流是不可控的。针对这类缺点,本文提出使用一种交-直-交变换器进行驱动电机,双可控的转换器能够实现电网侧的单位功率因数,同时无需大电容进行滤波,节约成本并且提高了功率密度。     

三电平变流器的压频转换式中点电位平衡控制方法研究

将三电平变流器运用于中高压游粱式抽油机,不仅可以节能降耗而且还可提高油井的采收率。然而,中点箝位式三电平变流器（NPc）的直流侧电压平衡问题直接影响变流器及其电机调速系统的可靠性。本文分析了其原因并提出压频转换式中点电位平衡控制的一种新方法,给出了利用87C196MC单片机实现的具体编程思路,通过软件仿真和实物实验证明了这种方法的正确性。     

PWM整流型变频调速系统降电容控制策略

为了改善系统的输入功率因数,并有效降低直流母线电容容量,本文对基于三相PWM整流的永磁同步电机变频调速系统展开了深入的研究,论证了PWM整流型变频调速系统降低直流母线电容的可行性,并提出一种基于功率前馈的降电容控制策略。该策略在传统的双闭环控制策略中增加了功率前馈环节以提高降电容后变频调速系统的稳定性。仿真结果表明所提降电容控制策略有效克服了直流母线电容较小情形下,整流侧和逆变侧功率强耦合引起的系统不稳定问题,改善了直流母线电压纹波特性。     

定子电流补偿与转子虚拟电阻协同控制策略

为解决电网电压骤升情况,研究双馈异步风力发电机在高电压穿越下的动态特性,设计出一种定子电流补偿与转子虚拟电阻协同控制的高电压穿越方案。虚拟电阻控制策略会增加直流母线侧电压,导致电网故障程度加重,定子侧增加电流补偿项的控制策略可以达到控制直流母线电压的作用。转子侧增加虚拟电阻和定子侧增加电流补偿项协同控制策略的方法,可以降低直流母线侧电压,缩短电压振荡过程,从而提高系统的高电压穿越能力。通过在Simulink仿真软件搭建增加转子侧电流补偿项的传统控制模型和定子电流补偿与转子虚拟电阻协同控制策略模型进行仿真,得出定子电流补偿与转子虚拟电阻协同控制策略可以有效抑制有功和无功功率、直流母线侧电压、电磁转矩和转子电流冲击幅度,同时加快母线侧电压恢复时间,提高系统故障穿越能力。     

A Dynamic LVRT Solution for Doubly Fed Induction Generators

Doubly fed induction generators have become the most common type of wind turbine generators. However, this type of generator is susceptible to grid-side low voltage and short circuits due to existence of a power electronics converter on the rotor side. When a short circuit or voltage sag happens on the grid side, the rotor current of the generator tends to rise, which could cause damage to the rotor converter. Design and implementation of a series converter on the stator side is presented in this paper to limit the current rise in the rotor. This system includes an active ac/dc inverter, three series transformers, and a dc-bus capacitor. To lower the rating of the components and make the system viable for practical solutions, an exponential decaying sinusoidal voltage, instead of a pure sinusoidal voltage, is applied by the converter during short circuit.      

Fundamental characteristics of five-level double converters with adjustable dc voltages for induction motor drives

In this paper, two kinds of control strategies for a three-phase five-level double converter are described on the assumption that the converter is applied to an induction motor drive system. The purposes of the proposed control strategies are to correct voltage imbalance of the DC-bus capacitors, to keep the input power factor at near unity, and to achieve an adjustable-speed drive. Characteristics of the converter operated by each of the two control strategies are examined and the validity is verified by experiments using a 3.7-kW induction motor.     

A Variable Frequency Phase-Shift Modulated Three-Level Resonant Single-Stage Power Factor Correction Converter

This paper presents a new single-stage three-level resonant power factor correction ac-dc converter suitable for high power applications (in the order of multiple kilowatts) with a universal input voltage range (90–265 Vrms). The proposed topology integrates the boost input power factor preregulator with a half-bridge three-level resonant dc-dc converter. The converter operation is controlled by means of a combination of phase-shift and variable frequency control. The phase-shift between the switch gate pulses is used to provide the required input current shaping and to regulate the dc-bus voltage to a set reference value for all loading conditions, whereas, variable frequency control is used to tightly regulate the output voltage. An auxiliary circuit is used in order to balance the voltage across the two dc-bus capacitors. Zero voltage switching (ZVS) is also achieved for a wide range of loading and input voltage by having a lagging resonant current in addition to the flowing of the boost inductor current through the body diodes of the upper pair of switches in the free wheeling mode. The resulting circuit, therefore, has high conversion efficiency and lower component stresses making it suitable for high power, wide input voltage range applications. The effectiveness of the proposed converter is verified by analysis, simulation, and experimental results.      

Experimental evaluation of direct torque-controlled 3-phase induction motor under inverter faults

ABSTRACT

In this paper, analysis and design of fault-tolerant converter topology for direct torque-controlled (DTC) induction motor (IM) drive suitable for low, medium and high power applications is proposed. The proposed converter topology can restore normal operation of the drive after the occurrence of open-circuit or short-circuit of power switches in the inverter. It consists of a current-controlled three-level boost converter (TLBC) to boost the dc-link voltage at input terminals of an inverter during post-fault, balance the voltages at dc-link capacitors and retains all the advantages of the conventional IM drive. Simulation and experimental results are presented for pre- and post-fault operation. The results are compared with conventional fault-tolerant DTC of the drive to highlight the merits of proposed converter.     

A Three-Level Resonant Single-Stage Power Factor Correction Converter: Analysis, Design, and Implementation

This paper presents a new single-stage power factor correction ac/dc converter based on a three-level half-bridge resonant converter topology. The proposed circuit integrates the operation of the boost power factor preregulator and the three-level resonant dc/dc converter. A variable-frequency asymmetrical pulsewidth modulation controller is proposed for this converter. This control technique is based on two integrated control loops: the output voltage is regulated by controlling the switching frequency of the resonant converter, whereas the dc-bus voltage and input current are regulated by means of duty cycle control of the boost part of the converter. This provides a regulated output voltage and a nearly constant dc-bus voltage regardless of the loading condition; this, in turn, allows using smaller switches and consequently having a lower on resistance helping to reduce conduction losses. Zero-voltage switching is also achieved for a wide range of loading and input voltage. The resulting circuit, therefore, has high conversion efficiency making it suitable for high-power wide-input-voltage-range applications. The effectiveness of this method is verified on a 2.3-kW 48-V converter with input voltage (90–265 Vrms).      

A new matrix converter motor (MCM) for industry applications

The trend in electrical drives is to integrate the frequency converter, the electrical motor, and even the gear or the pump into a single unit, in order to reduce the costs, to increase the overall efficiency and the equipment reliability. This paper presents the first integrated regenerative frequency converter motor for industry applications, based on a matrix converter topology. The low volume, the sinusoidal input current, the bidirectional power flow, and the lack of the bulky and limited-lifetime electrolytic capacitors recommend this topology for this application. This paper shows how the matrix converter disadvantages-the lack of bidirectional power devices, the lower voltage transfer ratio, and the overvoltages caused by the input filter during power-up-that have delayed the industrial implementation have been overcome. In order to demonstrate the validity of the solution, a 4-kW matrix converter motor prototype is built using a standard frequency converter motor enclosure for testing the requirements for an industrial drive. The tests demonstrate the good performance of the drive     

Modeling and design of a neutral-point voltage regulator for a three-level diode-clamped inverter using multiple-carrier modulation

The three-level diode-clamped multilevel converter commonly called the neutral-point-clamped converter has become established to be a preferred topology for high-power motor drive applications operating at several kilovolts. Although solutions to the problem of maintaining a stable neutral-point voltage in the converter continue to be the topic of research, a simple solution based on a design-oriented dynamic model of the system is not widely known. This paper presents the design, analysis, and implementation of a simple neutral-point voltage regulator for a three-level diode-clamped multilevel inverter, which uses a multiple-carrier sine-triangle modulator in conjunction with a closed-loop controller for neutral-point regulation. Redundant state choices are controlled via a continuous offset voltage that regulates the dc injection into the midpoint of the dc bus. A small-signal transfer function is developed in closed form, for neutral-point regulation, with the voltage offset as the control variable. Besides maintaining dc-bus voltage balance, the use of the approach leads to a significant reduction in the voltage distortion at the neutral point, allowing a definitive reduction in the required dc bus capacitance. Analytical, computer simulation, and experimental results verifying the approach are presented in this paper.     

Multiphase Bidirectional Flyback Converter Topology for Hybrid Electric Vehicles

For hybrid electric vehicles, the batteries and the drive dc link may be at different voltages. The batteries are at low voltage to obtain higher volumetric efficiencies, and the dc link is at higher voltage to have higher efficiency on the motor side. Therefore, a power interface between the batteries and the drive's dc link is essential. This power interface should handle power flow from battery to motor, motor to battery, external genset to battery, and grid to battery. This paper proposes a multi-power-port topology which is capable of handling multiple power sources and still maintains simplicity and features like obtaining high gain, wide load variations, lower output-current ripple, and capability of parallel-battery energy due to the modular structure. The scheme incorporates a transformer winding technique which drastically reduces the leakage inductance of the coupled inductor. The development and testing of a bidirectional flyback dc-dc converter for hybrid electric vehicle is described in this paper. Simple hysteresis voltage control is used for dc-link voltage regulation. The experimental results are presented to show the working of the proposed converter.     

Control of the single-phase three-leg AC/AC converter

This paper investigates the control of a single-phase three-leg ac/ac reversible converter in which a leg is shared by both the grid and the load side. Pulsewidth-modulation (PWM) techniques based on scalar and vector approaches are developed, introducing the concept of local and general apportioning factor and, also, a complete equivalence between scalar and space vector PWM. A hysteresis current controller capable of taking into account the shared leg is developed and a zero current error linear controller is presented. Furthermore, a control strategy to obtain maximum utilization of the dc-bus voltage is proposed. In addition, several relevant characteristics of the converter are addressed, such as voltage rating, harmonic distortion, shared leg and capacitor currents, and power rating. The converter is compared to four-leg and two-leg converters. Experimental results are presented.     

基于互补PWM控制的双功率变换在混合储能控制中的研究

为了克服在暂态过程中出现的电压跌路、负荷冲击导致的母线电压不稳定对微电网运行的影响,提出采用功率前馈和双闭环控制的双功率变换拓扑结构。该方案把超级电容和蓄电池结合,引入 双功率变换回路,对结构中两个功率半导体器件采用互补PWM控制,实现能量双向变换;建立了其状态方程模型,进行仿真;结果表明该结构及控制策略能有效的抑制暂态过程中直流母线的电压波动。