开关频率恒定与占空比调制相结合的PMSM-DTC控制

Direct Torque Control Based on Simple Duty Ratio and Fixed Switching Frequency for PMSM

针对永磁同步电机直接转矩控制(DTC)存在转矩脉动和磁链脉动大以及开关频率不恒定等问题,提出一种基于简单占空比的开关频率恒定永磁同步电机直接转矩控制。分析了电压矢量在不同转速和定子磁链位置对电磁转矩和磁链的影响,并设计了一种简单的占空比计算方式。PWM调制采用矢量控制的思想,使得逆变器开关频率恒定。仿真和实验结果表明,该方法能有效减少转矩和磁链脉动,保证逆变器的开关频率恒定,控制简单,动态性能好,鲁棒性强。

In order to overcome the problems of large torque, flux ripples, and variable switching frequency existing in the direct torque control （DTC） for the permanent magnet synchronous motors （PMSM） , an improved direct torque control strategy with a fixed switching frequency based on the simple duty ratio is proposed. The influence of the voltage vector on the torque and the flux with different angu!ar velocities and stator flux positions is analyzed. A simple calculation of the duty cycle is then designed. The PWM modulation is generated based on the vector control （VC） to ensure the fixed switch frequency of the inverter. Simulation and experimental results validate that the proposed method is simple and robust, can diminish the torque and flux turbulence effectively, ensure the fixed switch frequency, and has better dynamic performances.