异步电动机直接转矩控制转矩脉动最小化方法研究

在传统的异步电动机直接转矩控制中,低速运行时定子电流的低次谐波成分比较大,这导致电机在低速时存在较大的转矩脉动问题,针对此问题本文提出一种新的控制方法.在传统直接转矩控制的基础上,推导出异步电动机全速度磁链观测数学模型.为进一步提高转矩响应速度和减小转矩脉动,又在全速度磁链模型的基础上引入了模糊逻辑思想,提出了全速度模糊模型直接转矩控制.该模型把磁链相位角、磁链误差和转矩误差作为模糊变量,并对其进行合理的模糊分级,来优化电压空间矢量的选择.实验结果表明该方法不仅能够提高转矩响应速度,而且能够有效地解决转矩脉动问题,在全速度范围内具有较好的动静态性能.

Research on Torque Ripple Minimization Strategy for Direct Torque Control of Induction Motors

The large torque ripples exist in induction motors based on conventional direct torque control (DTC), especially at a low speed. On the basis of conventional DTC, the paper provides a new control strategy that can effectively reduce the torque ripples. A full-speed range flux model is deduced. The fuzzy logic idea is adopted in the strategy in order to further improve the torque response and decrease the torque ripples, so a full-speed fuzzy model DTC(FSFDTC) is presented based on the proposed full-speed range flux model. In the FSFDTC strategy, the stator flux angle, the stator flux error, and the torque error are reasonably fuzzified into several fuzzy subsets to optimize select of the voltage vector. The strategy is implemented with a single board microcomputer that uses TMS320LF2407A DSP. The experimental results illustrate that the torque response is improved, and torque ripples are effectively decreased. The system has a better dynamic and steady performance in full-speed range.