一种电机驱动用大功率网侧变流系统研究

提出了一种电机驱动用高性价比大功率网侧变流系统。主电路采用二极管整流器与PWM整流器并联,充分利用二极管整流器简单可靠、成本低,以及PWM整流器能量双向流动、功率因数高的优点,不仅能够省去传统电机驱动中的制动电阻,节约电能,还能提高交流系统功率因数。控制上通过对二极管整流器输出特性的研究,并调节PWM整流器输出特性,实现了PWM整流器与二极管整流器的协调工作。仿真和试验验证了主电路方案及控制方法的有效性。     

能馈式级联型高压变频器运行特性研究

基于传统级联型变频器驱动的高压异步电动机只能电动运行,为克服这一不足,提出了一种能馈式级联型高压变频器。用PWM整流器替代传统级联单元的不控整流桥,并对输入电流进行直接控制,在异步电动机处于再生制动状态时,输入电流自动反相,将再生能量回馈到电网,进而实现异步电动机的再生运行。所提出的新型高压变频器具有输入电流波形近似正弦,谐波污染小,自动实现能量双向流动,节能效果明显等优点。仿真和实验研究结果证明了该新型变频器的正确性和可行性。     

Braking Scheme for Vector-Controlled Induction Motor Drives Equipped With Diode Rectifier Without Braking Resistor

This paper deals with sensorless vector control of pulsewidth-modulated inverter-fed induction motor drives equipped with a three-phase diode rectifier. An electronically controlled braking resistor across the dc link is not used. Instead, the power regenerated during braking is dissipated in the motor while a dc-link overvoltage controller limits the braking torque. Losses in the motor are increased by an optimum flux-braking controller, maximizing either the stator voltage or the stator current depending on the speed. Below the rated speed, the braking times are comparable to those achieved using a braking resistor. The proposed braking scheme is very simple and causes no additional torque ripple. Experimental results obtained using a 2.2-kW induction motor drive show that the proposed scheme works well.     

A 4-kW 42-V induction-machine-based automotive power generation system with a diode bridge rectifier and a PWM inverter

The electrical load demand in automobiles has been increasing steadily due to the usage of several subsystems to improve engine performance, passenger comfort, and safety. The current production Lundell alternator is not able to meet the future growing power demand due to its inherent design limitations. Therefore, an efficient, high-power generation system is needed to meet the growing electric power demand in automobiles. The trend to adopt the 42-V power system in automobiles allows one to add more subsystems in an efficient way. In this paper, a three-phase 42-V 4-kW induction-machine-based automotive power generation scheme is proposed to meet the future electrical power demand in automobiles. This scheme uses a low-cost diode bridge rectifier directly connected to the induction machine to transfer active power to the battery and the load. The excitation to the machine is supplied by means of a low-power pulsewidth-modulation (PWM) inverter to control the output voltage of the generator connected to the diode bridge rectifier. This paper presents a new control methodology to regulate the output voltage of an induction generator directly connected to a diode bridge rectifier by controlling the auxiliary PWM inverter. The simulated performance results of a 4-kW 42-V induction generator scheme at various speeds and loads are presented.     

A new single-phase to three-phase converter with active inputcurrent shaping for low cost AC motor drives

A new single-phase to three-phase power converter for a low-cost AC motor drive is proposed. The proposed converter employs only six switches and incorporates an active input current shaping feature that results in sinusoidal input current at close to unity power factor. The front-end rectifier in the proposed converter permits bidirectional power flow and therefore provides for excellent regulation against fluctuations in source voltage. This feature also facilitates regenerative braking of the AC motor drive. An easy to implement control strategy to maintain near unity power factor over the full operating range is detailed. Suitable design guides for the selection of filter components is presented. Simulation and experimental results are given to verify the developed theoretical models     

一种开关磁阻电机驱动系统绕组能耗制动方式研究

针对基于整流桥交流供电的小惯量开关磁电机驱动系统,为了避免开关磁阻电机(switched reluctance motor,SRM)再生制动运行时能量回馈对母线器件的冲击,本文采用了一种SRM绕组能耗制动方法,将制动产生的能量消耗在电机定子绕组上,通过对SR电机绕组能耗制动深入分析和仿真计算,提出了一种开关磁阻电机绕组两相直通绕组能耗制动控制方法,无需专门制动电阻泄放回路,在保证安全快速制动的前提下,简化了驱动系统的结构。以一台基于整流桥供电的四相8/6开关磁阻电机为应用对象,阐述所提方法的具体实施办法。研究结果表明该方法既可以产生必要的制动转矩,又可以避免制动能量回馈对母线电子元器件的冲击,提高了制动过程的可靠性和安全性。     

一种带有PWM变换器的汽车感应发电机系统

讨论了一种三相42 V/4 kW汽车感应发电机系统设计方案,以满足未来对车载电源功率的需求。该方案采用一个与感应发电机直接相连的低成本二极管桥式整流器将有功功率传递给蓄电池和负载,感应发电机的励磁电流由一个小功率PWM变换器提供。同时,这里还提出了一种新颖的控制策略来控制发电机的输出电压,它主要通过控制一个辅助的PWM变换器来实现。通过对一辆桑塔纳2000的电路进行改造,在一台42 V/4 kW的实验样机上进行实验,得出此发电机系统在不同发电机转速和不同负载条件下的性能曲线。     

减速过程中变频器的换流方式

分析在感应电动机再生制动过程中变频器逆变桥的运作机理。指出：无论在电动状态还是在发电状态下，PWM控制规律没有变化；但由于转子电流方向相反，定子电流与定子电压间相角差发生很大变化。在再生制动过程中，功率器件的电流方向发生颠倒，电动机向电源回馈能量。     

能量回馈单元中双载波SPWM环流抑制研究

变频器能量回馈装置可实现将电机再生制动的能量从变频器的直流母线回馈到交流电网中,但是由于能量回馈装置与变频器的二极管整流桥并联这一特殊结构,使得能量回馈装置运行时系统内部容易产生环流,导致变流器损耗增加,降低系统效率。通过对环流产生时的等效电路进行分析,得出环流大小主要与零开关矢量有关,进而提出一种双载波空间电压矢量控制(SVPWM)方法,通过该方法来改变逆变器的开关状态,使得逆变器不输出零矢量来抑制环流。该方法不需要增加额外硬件成本,且能有效抑制环流。仿真和实验结果表明了该方法的有效性。     

Development of an Induction Machine Commutated Thyristor Inverter for Traction Drives

Several designs detailing the construction of brushless cage-rotor induction machines operating at unity or leading power factor at the 35-hp level have recently been published [1]-[3]. The experimental machine combines the torque characteristics of a conventional cage induction machine with the leading power-factor (PF) capability of an overexcited dc field synchronous condenser into one unit using a common cage rotor and a common stator core. The ability of this machine to naturally commutate a high-power current-source thyristor inverter is apparent without any need for capacitors. The preferred adjustable speed propulsion arrangement consists of a mains-fed phase-delay-rectifier (PDR), high-voltage dc link, and a current-source inverter powering a ten-pole traction motor with constant V/Hz control. The drive system provides continuously variable torque during motoring, and regenerative braking modes and specific details are given for a 150-hp cage-rotor traction motor and converter, capable of natural commutation up to 200 Hz, currently under development.     

开关磁阻电机再生制动控制方法

针对开关磁阻电机再生制动控制中存在制动电流波动大的问题,提出一种基于电流预测的开关磁阻电机再生制动控制方法.分析了电机制动过程中其对应功率开关的工作模式及相应状态向量的确定方法,研究了基于电流预测的开关磁阻电机再生制动控制的具体设计方法,并对其效果进行了仿真验证,同时与传统变制动相电压占空比控制法进行了对比仿真分析,结...     

PAM inverter system with power-factor-corrected converter

In most cases, PWM power-factor-corrected (PFC) converters are constructed from a diode rectifier and an active power circuit such as a boost or buck-boost chopper. Besides the PFC operation, the active power circuit can control the dc output voltage. The output voltage of the PAM inverters is controlled by varying the level of the dc input voltage. The PAM method reduces the voltage and current stresses of the inverter and motors. This paper proposes a new PAM inverter system with high power factor converter to obtain a sinusoidal input current. The proposed PAM method to reduce the torque ripple in the induction motor can reduce switching losses by providing a pausing interval where the switching operation stops during part of one period. © 1998 Scripta Technica, Electr Eng Jpn, 124(2): 43–52, 1998     

3kW开关磁阻电机的再生制动实现

该文分析了开关磁阻电机再生制动的原理和控制方法,给出了一套3kW开关磁阻电机再生制动的设计实例,在电流控制的基础上解决了位置检测、优化控制以及系统保护等再生制动过程中不容忽视的问题.理论和实践表明,在电流控制的基础上,中小功率开关磁阻电机具有优良的再生制动性能,这对降低系统成本、提高系统性能/价格比和开拓开关磁阻电机的多种应用具有重要意义.     

A method for improving the energy efficiency of an alternating current electric locomotive in the regenerative braking mode

A method for improving the power factor of an ac locomotive with the commutator motor operating in the regenerative braking mode is proposed. The method improves the control system algorithm of the power converter. The new switching method of inverter thyristors regulates the curve of the instantaneous power during the main switching. It allows reducing the period in which the energy flow passes to the locomotive, leading an increase in the average value of the instantaneous power. A “traction substation–electric traction network–locomotive in the regenerative braking mode” mathematical model is presented to verify efficiency of the method. The model consists of several interacting electric power substations, a section of electric traction grid, a locomotive power transformer, a four-zone inverter, a control system of reversible converter, and a dc circuit. The model is realized in the OrCAD software.     

Crowbar电路在风电并网低电压穿越中的应用

基于电力系统对风电并网中,风机需要具备低电压穿越性能,即电网电压波动时风机可以不脱离运行并向电网回馈能量,通过对三电平整流器的SVPWM的控制算法、二极管钳位型三电平变流器和电网跌落对风电变流器的影响三方面的研究,针对大功率直驱变流器提出一种基于耗能型的Crowbar电路,相比于传统保护电路和控制策略增加了制动单元,并设计了其中开关管的控制方法,来实现低电压穿越的能力。并通过1.5 MW的直驱风电机组及并网变流器构成并网系统验证设计的合理性。     

Characteristics of a Controlled-Current PWM Rectifier?Inverter Link

Two controlled-current pulsewidth-modulated (PWM) converters have been integrated into rectifier-inverter links of variable-speed ac motor drives. The authors focus on developing a mathematical model of the rectifier-inverter link and presenting experimental justification of the model. The characteristics of the rectifier-inverter system and the constraints imposed by the voltage feedback loop and dc link voltage are discussed. The rectifier-inverter system is made to drive a ``selfcontrolled' synchronous motor, thus forming a system for which both the utility and the motor currents are near sinusoidal. The optimized power conversion capability of the motor is now matched by unity power factor operation on the rectifier side. Fast reversal from motoring to regenerative braking capability is demonstrated experimentally.     

Three-phase active harmonic rectifier (AHR) to improve utility input current THD in telecommunication power distribution system

Modern telecommunication power supply systems have several parallel-connected switch-mode rectifiers to provide -48 V DC. A typical switch-mode rectifier configuration includes a three-phase diode rectifier followed by a DC-DC converter. Such a system draws significant harmonic currents for the utility, resulting in poor input power factor and high total harmonic distortion. In this paper, a three-phase active harmonic rectifier (AHR) scheme is proposed. In the AHR scheme, a diode rectifier module is replaced by a six-insulated-gate-bipolar-transistor pulsewidth-modulation rectifier to supply load harmonics as well as its own active power. Each DC-DC converter module is connected to a shared 48-V DC link. The AHR module together with parallel-connected switch-mode rectifiers is controlled to achieve clean input power characteristics. The VA ratings of the AHR scheme is compared with an active power filter approach. The control design is based on the synchronous reference frame approach. Analysis, simulation, and experimental results show that the AHR offers several advantages such as lower VA rating, better current control response, efficient use of the AHR DC link, small size, and stable DC-link voltage control.     

基于电阻能耗制动和双频制动的新型电机制动方法

现代传动系统主要由“变频调速系统-电动机-工作机械”组成,电机如何制动是变频器设计的重点。提出一种由电阻能耗制动和双频制动相结合的新型制动方法,结合了这两种制动方法的优点,给出了控制算法流程图,并通过电力系统仿真软件PSCAD进行了仿真研究,对电机转速、逆变器输出频率及输出A相电流进行了监测,结果表明该方法具有很好的制动效果,各项性能指标均达到设计要求。     

Induction motor drive behavior during unbalanced faults

The ability of an induction motor drive to ‘ride through’ short-term power system faults or voltage dips of several cycles is of interest in processing plants where shutdowns are expensive. In this paper, the rectifier/inverter induction motor drive is modeled to include the effects of an unbalanced supply circuit, such as that caused by a fault in the supply. A three-phase diode bridge rectifier is used to simulate the effects of the overlap angle caused by the unbalanced source reactance and associated harmonics. The filter circuit between the rectifier and inverter is included. A detailed switching function model is chosen for the inverter so that generated harmonics are included in the motor voltage. Experimental results are included.     

Power factor improvement of single‐phase diode rectifier circuit by field‐weakening of inverter‐driven IPM motor

This paper proposes a novel inverter drive system to improve the input power factor of single‐phase diode rectifier. Conventional rectifiers need a high‐frequency switching device and a reactor to improve the input power factor. However, the proposed power converter does not need the switching device, electrolytic capacitor, or reactor. By making many ripples across the DC‐bus voltage, the input power factor can be improved. The proposed system consists of only a single‐phase diode rectifier, small film capacitor, three‐phase inverter, and motor. The proposed system adopts an interior permanent magnet (IPM) synchronous motor. The IPM motor is well known as a high‐efficiency motor and can realize field weakening. The basic ideas of the inverter control method are based on the following operations: the inverter's controlled synchronous with the DC‐bus ripple voltage by field‐weakening method, and direct active power feeding from the source side to the motor without smoothing the DC‐bus voltage. This paper describes that the proposed method can obtain an input power factor of 97.3% by experimental tests, and realizes the goals of small size and long life of the system. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(2): 66–73, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20047