【摘要】 针对永磁同步电机直接转矩控制转矩和磁链脉动大、开关频率不恒定的问题,对转矩脉动和开关频率不恒定原因进行分析,结合占空比和SVPWM调制思想,提出了一种新型PWM调制的永磁同步电机模型预测直接转矩控制。采用代价函数代替传统直接转矩控制的电压矢量选择表,根据转矩和磁链的综合误差确定所选有效电压矢量以及占空比,将选择的有效电压矢量和零电压矢量按空间电压矢量合成顺序产生使开关频率恒定的PWM。另外,考虑到采样和控制的延时,对转矩和磁链进行多步预测,提前一个控制周期计算并输出所需要的PWM波。仿真和实验结果表明,基于新型PWM调制的PMSM模型预测直接转矩控制方法能够使逆变器开关频率恒定,降低相电流的谐波含量,进而有效抑制转矩和磁链脉动,提高了DTC的转矩控制精度。更多还原

【Abstract】 For the problem which exists in traditional direct torque control( DTC) of permanent magnet synchronous machine( PMSM),such as high torque ripple,high stator flux ripple and inconstant switching frequency,model predictive direct torque control( MPDTC) with a minimum torque ripple and constant switch frequency based on duty ratio modulation and the new pulse width modulation( PWM) of vector control was proposed. The traditional DTC voltage vector selection table was replaced by the cost function of MPDTC. The duty ratio of the selected voltage vector was calculated based on the comprehensive error of torque and flux linkage. The PWM with constant switching frequency was generated by the selected active voltage vector and zero voltage vectors. The delay time caused by sampling and control is considered at the same time. The PWM is obtained ahead of a control cycle based the idea of model predictive control( MPC). The simulation and experimental results show that the inverter switching frequency is constant and the harmonics of the phase current are reduced. The torque and flux ripples are restrained based on model predictive direct torque control( MPDTC) with duty ratio and constant switch frequency effectively.更多还原