降低感应电机直接转矩控制的转矩脉动的控制器

A Reduced Torque Ripple Controller for Direct Torque Control of Induction Machines

基于磁滞比较器和选择表的感应电机直接转矩控制(DTC),其开关频率可变,且转矩脉动大,特别在低速时。这是因为转矩和磁通的变化率以及转矩和磁通达到其上带和下带所花的时间随运行工况变化。文中提出了一种新型的开关频率固定的转矩控制器。新型控制器结构非常简单,其输出类似于传统的三点式磁滞比较器。就提出的控制器介绍了近似频域分析法,作为控制器参数选择的指南。介绍了感应电机直接转矩控制采用该转矩控制器进行的仿真和实验结果。结果表明提出的控制器可以保持开关频率恒定,并降低了转矩脉动,尤其在低速时。

Direct Torque Control(DTC) of induction machines(IM),based on hysteresis comparators and selection table,suffers from variable switching frequency and large torque ripple,especially at low speed.This is because the rate of change of torque and flux and hence the time taken for the torque and flux to reach their upper and lower bands,varies with operating conditions.In this paper a new torque controller with fixed switching frequency is proposed.The structure of the new controller is very simple,with its output simlar to that of the conventional three-level hysteresis comparator.The approximate frequency domain analysis of the proposed controller is presented,which served as a guide for the controller' s parameters selection.The simulation of the DTC of IM with the proposed torque controller is presented,which is verified by experimental results.The results indicate that the proposed controller is capable of maintaining the torque switching frequency constant and reducing the torque ripple,particularly at low speed.