占空比调制的永磁同步电机直接转矩控制

Direct torque control of permanent magnet synchronous motor based on duty ratio control

针对如何确定占空比调制的永磁同步电机直接转矩控制的零矢量作用时间问题。根据电压矢量与电流转矩分量关系,分析了在不同转速下零矢量作用时电磁转矩的变化规律,引入占空比调制后低速区转矩脉动要小于中高速区转矩脉动。设计了基于占空比调制的永磁同步电机直接转矩控制系统,利用转矩偏差和定子磁链的偏差计算占空比,该方案易于实现,对电机参数误差不敏感。仿真和实验结果表明,该方法结构简单、鲁棒性强,能够明显改善低速性能。

Calculation duty ratio is an important issue in Direct torque control （ DTC） of permanent mag-net synchronous motor （ PMSM） based on the duty ratio modulation. The effect of zero vector on elctro-magnetic torque during all speed range was analyzed on the basis of the relation between voltage vector and torque current component and an important phenomenon was revealed and explained that torque rip-ple in low speed range is less than that in high speed range in DTC based on the duty ratio modulation. A robust DTC method of PMSM based on the duty ratio control was designed in which the duty ratio is cal-culated with the error of torque and flux. The method is simple to implement and insensitive to motor pa-rameter error. Simulation and experiments are carried out and show that the improved DTC based on duty ratio modulation has the advantage of simplicity, robustness and improved performance in low speed.