Current-Source Converter for AC Motor Drives

The employment of current-source concepts in thyristor converters to obtain adjustable frequency and adjustable current waveforms is presented. The use of a dc filter choke and a current feedback loop to produce a regenerative current source is explained. The simplified inverter commutation circuit made possible by the current-source technique is also discussed. Finally, a brief review of the inherently rugged current-source converter's ability to provide wide range control of an ac induction motor is given.     

基于电流型Z源交流调压器的电机调速系统

提出了基于电流型Z源交流调压器的电机调速系统.这种新型的Z源交流调压器系统引入了独特的LC网络,减少了由于开关直通或开路造成的过电流和过电压.通过控制双向电力电子开关的占空比,这种系统可以提供升降压功能.因而,在电网电压跌落时,可以为电机提供渡越能力,减小网侧的电流谐波,提高功率因数和系统的可靠性.仿真和实验结果验证了理论分析的正确性.     

基于电流源变流器的永磁同步电机驱动系统全状态变量预测转矩控制

电流源变流器输出电压平滑、具有天然短路保护能力,在长电缆驱动、中压驱动等场景得到广泛应用.电流源变流器的输出滤波电容与电机的电磁动力学方程构成二阶系统,存在天然的谐振频率,易失稳,因此对控制器的设计提出了严峻挑战.该文深入地分析了被控对象的数学模型,在不考虑控制变量和状态变量约束的条件下,理论上求解了可实现电磁转矩的无差拍控制的输入电压值,以此作为滤波电容电压的参考值.在此基础上,充分利用模型预测控制多目标全局优化的能力,将dq轴电流、输出电容电压和开关惩罚项包含在一个统一的代价函数中,提出一种计及全状态变量的预测转矩控制策略.所提的全状态变量预测转矩控制可有效抑制滤波电容和定子电感之间的能量振荡.在此基础上,通过理论分析和大量仿真数据获取采样频率和开关惩罚项权系数的设计准则,通过选取合理的开关惩罚项权系数,可实现开关频率和稳态控制性能的优化设计.最后,通过硬件在环(HiL)对所提控制策略进行了验证.测试结果表明,全变量预测转矩控制稳态转矩脉动小;在动态转换过程中,转矩响应速度快.     

Performance Improvement of Current Source Inverter-Fed Induction Motor Drives

A high performance variable speed drive system using current source inverter fed induction motor is described. The principle of the drive control is based on the field-orientation method, where the stator current is used as the vector quantity. To improve the system response and to operate smoothly at low speed, a current pulsewidth modulation (PWM) control is provided by means of a feedback loop. This system operates stably and shows a high dynamic performance in a wide range, from zero to rated speed. Dual current source inverter is applied to this drive system which results in a remarkably low copper loss of the motor, even in PWM operation.     

Current Control for AC Motor Drives Using a Single DC-Link Current Sensor and Measurement Voltage Vectors

A new algorithm using a single dc-link current sensor to reconstruct all three inverter phase currents has been proposed that overcomes problems caused by the presence of regions in the voltage vector plane where the phase currents are not conveniently measurable. The measurement vector insertion method (MVIM) achieves this objective by applying additional active voltage vectors for brief intervals only when needed during each fundamental frequency cycle. This paper addresses techniques for incorporating the MVIM algorithm into a closed-loop current regulator designed to provide high-quality current control using a single dc-link current sensor. Virtual active resistance state feedback is introduced into the synchronous-frame current regulator in order to improve the controller's ability to reject disturbances caused by the MVIM measurement vectors. Experimental results are provided to confirm the attractive performance characteristics of the resulting current reconstruction and regulation using the MVIM algorithm     

A Simple Control System for Current Source Inverter-Fed Induction Motor Drives

A simple control system for induction motor drives with the current source inverter is presented. This system is based on the idea of field-orientated control. In contrast to well-known ways of realization a torque proportional quantity is calculated from stator voltage and current without explicit flux calculation or integration. A speed sensor is not required. The theoretical principles of this method are discussed. Some transients which illustrate the performance of some different system variants are presented.     

开绕组电机驱动用双三电平逆变器的共模电压差抑制

开绕组电机驱动用双三电平逆变器拓扑在中压大功率变频驱动领域具有较好的优势。针对共直流源的开绕组拓扑共模电压差抑制的问题,提出了一种基于零序注入的SPWM调制策略,将两组逆变器的调制矢量互差120°后分别注入幅值相同的三次零序电压,保证系统任意时刻的低频和高频共模电压差均为零。在此基础上为了解决中点电压脉动问题,需要进一步的零序电压注入,同时不影响系统共模电压差抑制。文中通过仿真和实验证明了该调制策略的可行性和有效性。     

Diminution of Current-Measurement Error for Vector-Controlled AC Motor Drives

The errors generated from the current-measurement path are inevitable, and they can be divided into two categories: offset errors and scaling errors. Current data including these errors cause the periodic rotor speed ripples, which are one and two times the fundamental stator current frequency. Since these undesirable ripples can harm the motor drive system, a compensation algorithm must be included in the motor control drive. In this paper, a new compensation algorithm is proposed. The principal feature of the proposed algorithm is the use of the integrator output signal of the$d$-axis proportional plus integral (PI) current regulator. This output signal is nearly zero or constant because the$d$-axis current command is zero or constant, so that the maximum torque or unity power factor can be acquired in the ac drive system. If the stator currents include offset and scaling errors, the integrator output signal of the$d$-axis PI current regulator ripples in the rotor speed of the same frequency. The proposed compensating algorithm for the current-measurement errors can be easily implemented by subtracting the dc offset value or rescaling the input measurement gain of the stator currents. Therefore, the proposed algorithm has several advantages: it is robust with regard to the variation of the motor parameters; it is applicable to steady and transient states; it is easy to implement; and it requires less computation time. The MATLAB simulation and the experimental results verify the usefulness of the proposed current compensating algorithm.     

一种新型交交变换器的研究

提出了一种新颖的适用于航空变频电源(360～800Hz)的交交变换器。它由双升压式整流器和双降压式逆变器直接连接构成,继承了它们无桥臂直通隐患、无体二极管反向恢复的优点,同时具有可靠性高和效率高优点。简要介绍了该变换器工作原理,提出了直流母线电压的选取原则以及如何优化设计中间环节滤波电容,仿真和实验验证了理论分析的正确性。     

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。     

Transient Performance of Permanent Magnet AC Motor Drives

The transient behavior of permanent magnet ac motor drives is analyzed. A new model is proposed where particular emphasis is placed on the role that armature reaction and saturation effect play on the flux distribution of the machine. Equations for calculation of these fluxes are deduced and verified by experimental tests on the machine. Simulation of motor transients both for constant and variable speed operations are presented and compared with experimental tests.     

New Approach to a High-Power GTO PWM Inverter for AC Motor Drives

A control method for GTO PWM inverter parallel-set operation and a new protection system for prevention of short-circuit faults caused by turn-off failure, both to realize a high-power drive system are described. Timing control of GTO gate pulse command provided by a feedback loop, and a reactor at the output of the inverter can minimize the cross current flowing between inverters and can balance the output current of each inverter in inverter parallel-set operation. This method eliminates the necessity of selecting GTO's of equal characteristics, and can apply to parallel-set operation of three or more inverters. The new protection system judges the on and off states of the GTO from the GTO gate-cathode voltage and detects turn-off failure of the GTO. This method positively stops the inverter system safely and reliably upon turn-off failure of the GTO. Experiments are carried out on a 30-kVA inverter and two sets of 450-kVA GTO inverters.     

Three‐Phase Current Control by Dynamic Reconstruction of Undetected Currents for AC Motor Drives

This paper proposes new three‐phase current control methods for AC motor drives, which detects only a phase current from among three‐phase currents. The first proposed method first detects a phase current, and then estimates the two‐phase current in the stationary reference frame using the detected single phase current. The second proposed method first detects a phase current, then synthesizes the two‐phase quasi‐current in the dq rotating reference frame, and finally produces two‐phase current estimates by extracting the positive‐phase component from the quasi‐current. The third proposed method produces two‐phase current estimates by filtering out the negative‐phase component from the quasi‐current. This paper presents the principles and detailed characteristic analyses of the proposed methods and validates them on the basis of extensive experiments.     

交流变频调速传动装置用新型电力半导体器件

电力半导体器件的发展大大促进了交流变频调速传动装置性能的改善，ＭＯＳ栅结构的现代器件的开发成功，可以用很小的输入功率来控制很大的输出功率，并可大大降低装置的功耗，提高工作频率。具有优良反向恢复特性的整流二极管的开发成功，大大降低了高频工作下的功耗。目前的开关器件都是用硅材料制成，但利用ＳｉＣ等材料制成的电力开关器件具有很优良电气特性，是研制理想器件的关键。     

Load Sharing of Dual Motor Grinding Mill Drives

Relatively small slowly varying shaft position and velocity variations superimposed on the normal running speed of dual drive grinding mill motors can cause individual motor torque variations which disturb load sharing. The magnitude of load or torque unbalance is a function of the magnitude of the mechanical variation, the type of motors used, i.e., induction or synchronous, the number of motor poles, and the ratio of the gear connecting the motors to the load. When the magnitude is large enough to be of concern, it can be compensated for through motor secondary or field controls. How the causative factors relate, how dual drive motors should be specified for purchase are discussed, and a compensating load sharing controller for dual drive synchronous motors is described.     

三电平双PWM变频调速系统研究

文章以三电平PWM变频器为例介绍了一种新型的双PWM变频调速系统，此系统通过可控的整流部分来实现控制系统功率因数和无功功率的控制，从而使变频器成为一清洁的电源。     

Current Controller for Autocommissioned Vector-Controlled Induction Motor Drives

A current controller composed of a current regulator associated to a parameter adaptation scheme is proposed. The current regulator considers the inherent coupled structure of the induction machine. The adaptive block is coupled to this regulator in order to carry out a high performance current control with low sensitivity to parameter variations. It is shown that this controller can also be used to estimate the machine saturation characteristic and the rotor time constant as part of an indirect vector control autocommissioning procedure. A discrete time approach is utilized for the design considering microprocessor implementation.     

电流源变频器供电异步电动机谐波电流的仿真与分析

根据梯形PWM技术的原理,通过仿真模型的建立来重点分析电流源变频器供电直流回路中的大电感和负载侧的并联电容对电动机的定子和转子的谐波电流、转矩和转速的影响。     

AC Motor Drives With a Reduced Number of Switches and Boost Inductors

This paper presents eight three-phase ac motor-drive configurations that operate with a reduced number of switches and boost inductors. Four of the configurations are single-motor drives, and four of the configurations are double-motor drives. The drives provide both bidirectional power flow and power-factor control. This paper presents the analysis and control strategy of the systems, including current control and pulsewidth-modulation strategy. In spite of using a reduced number of components, the dc-link voltage and the machine currents of some of the proposed configurations are not much larger than the equivalent values of the conventional configurations. These drive systems are suitable for applications where the size of the system is a critical factor. The experimental results demonstrate the feasibility of the proposed topologies     

基于永磁同步电机的电流源型风电变流器实现

永磁直驱式全功率风电变流器具有结构简单、转换效率高、低成本、可靠性高等优势,是目前风力发电领域的一个重要研究方向。电流源型变换器跟电压源型变换器相比,具有出色的低电压穿越能力、易并联、高可靠性等优点。因此提出了基于永磁同步电机的电流源型风电变流器的实现方法,包括变换器的参数设计、有功和无功的控制策略、有源阻尼的实现。基于提出的控制策略,可以实现一个完整的电流源型PWM变流器。最后给出了提出的控制策略的MATLAB仿真结果。