不对称永磁同步电机级联直接转矩控制策略

摘要

The parasitic impedance of permanent magnet synchronous motor will result in the unbalance of the three-phase current of the motor,thus the motor torque ripple is increased. To mitigate the problem,the unbalanced back electromotive force of the motor was analyzed and deduced,the torque harmonic expression was solved firstly, then a cascade direct torque control strategy for torque ripple optimization of asymmetric permanent magnet synchronous motor was presented. Theα,βcomponents of the motor stator flux and current were extracted to generate the positive and negative sequence components of the reference voltage vector. Then the positive and negative sequence components of the reference voltage vector were synthesized ,which would build the corrected reference voltage vector for space vector modulation algorithm. At the same time ,the conventional PI regulator was improved into a composite PIR regulator combined with a PI regulator and a resonant controller. Finally ,the steady-state and dynamic test results verify the effectiveness of the proposed control strategy.%永磁同步电机各相的绕组阻抗不平衡将导致电流不对称,从而增加了电机转矩脉动.针对不平衡问题,首先对电机不平衡反电动势进行了分析推导,解析求解了转矩谐波表达式,进而设计了一种抑制转矩脉动的不对称永磁同步电机级联直接转矩控制策略.新方案通过提取电机定子磁链和电流的α,β分量来生成正负序的参考电压矢量,并将两者合成以生成修正参考电压矢量用于空间矢量调制算法.同时方案中将传统PI调节器改进为PI调节器和谐振控制器相结合的复合PIR调节器.最后,稳态和动态对比试验结果验证了所提出控制策略的有效性.