永磁同步电机转矩脉动占空比最优控制方法

Torque Ripple Suppression Method of PMSM Based on Duty Ratio Optimization

传统直接转矩控制(DTC)在每个控制周期内仅作用单一的电压矢量,存在转矩脉动大和开关频率不固定等缺点。针对上述问题,提出了一种基于占空比优化的永磁同步电机(PMSM)转矩脉动抑制方法。建立了PMSM调速系统的基本数学模型,推导了非零电压矢量和零电压矢量对应的转矩变化率,并指出数字系统的离散化特性和单一的转矩变化趋势是造成转矩脉动过大现象的本质原因。采取占空比优化的方式在一个控制周期内输出一个主矢量和一个零矢量,以单个控制周期内转矩脉动均方值最小为原则,推导并计算出主矢量对应的最优占空比。样机实验结果表明,该方法在保留传统DTC高动态响应的基础上,可以减小电磁转矩脉动、固定开关动作频率,有效地提升了PMSM调速系统的稳态性能。

Traditional direct torque control （DTC） apply only one voltage vector in each control cycle, which brings the drawbacks of high torque ripple and variable switching frequency. To solve this problem, a torque ripple suppression method of permanent magnet synchronous motor（PMSM）based on duty ratio optimization was proposed. A basic mathematical model of PMSM speed control system was established, the torque change rate of non-zero voltages and zero voltages were derived. We pointed out that the fundamental of large torque ripple is caused by the digital system discrete characteristics and single torque change trend. Take the way of duty ratio optimization, a main vector and a zero vector were applied in one control cycle. Based on the principle of torque ripple RMS minimization during one control period, the optimal duty ratio of the non-zero vector was obtained. Prototype experiment results show that the method retains the high dynamic response ability of the traditional DTC, it can reduce the electromagnetic torque ripple and fixe switching frequency, then the steady-state performance of PMSM control system can be improved effectively.