稳态性能改善的永磁同步电机模型预测磁链控制

Model predictive flux control for enhancing steady-state performance of permanent magnet synchronous motor

关键词:  永磁同步电机  模型预测磁链控制  共模电压  转矩脉动  电流谐波

Key words:  permanent magnet synchronous motor  model predictive flux control  common-mode voltage  torque ripple  current harmonic

摘要:

为抑制电机共模电压的同时兼顾较好的稳态性能,提出一种模型预测磁链控制方法。首先,改进H8逆变器扩展备选电压矢量,将零矢量引入备选矢量集,减小电流谐波含量；其次,根据磁链误差矢量快速选择电压矢量,保证较小的转矩脉动、较低的电流谐波含量,并且考虑死区时间(dead-time,DT)对共模电压的影响,规定所选电压矢量的作用顺序,避免可能产生的等效零矢量；然后,基于磁链无差拍控制原则,设计新的电压矢量占空比的计算方法以减小磁链脉动;最后,将所提控制方法与3矢量法、5矢量法、8矢量法3种抑制共模电压控制方法进行仿真对比。研究结果表明:所提控制方法可以避免死区共模电压尖峰的产生,相较于3矢量法和8矢量法,其共模电压幅值分别降低了66.67%和33.33%；同时,有效减少了电机的转矩脉动、磁链脉动以及电流谐波含量。所提控制方法可以在抑制共模电压的同时改善电机的稳态性能,并且降低了计算复杂度。

Abstract:

To suppress motor common-mode voltage while maintaining good steady-state performance,a model predictive flux control method was proposed. Firstly, the H8 inverter′s candidate voltage vectors are expanded by incorporating zero vectors into the candidate set to reduce the current harmonic content. Secondly, according to the flux error vector, the voltage vectors are rapidly selected, which ensures low torque ripple and low current harmonic content. Moreover, Considering the influence of dead-time (DT) on common-mode voltage, the action sequence of the selected voltage vectors is defined to avoid potential equivalent zero vectors. Then, based on the flux beat control principle, a new calculation method of voltage vector duty cycle is designed to reduce flux pulsations. Finally, the proposed control method is compared with the three-vector method, five-vector method and eight-vector method which can suppress the common-mode voltage. The results show that the proposed control method can avoid the dead-time common-mode voltage peak. Comparing with the three-vector method and the eight-vector method, the common-mode voltage amplitude is reduced by 66.67% and 33.33%, respectively. At the same time, the proposed control method can effectively reduce the torque ripple, flux ripple, and current harmonic content of the motor. The proposed control method can improve the steady-state performance of the motor while suppressing the common-mode voltage, and reducing the computational complexity.