高速磁悬浮无刷直流电机无位置换相误差闭环校正策略

Closed Loop Control Strategy to Correct the Commutation Error of High-Speed Magetically Suspended Brushless DC Motors without Position Sensor

针对基于线反电动势的高速磁悬浮无刷直流电机无位置换相误差问题,分析了PAM调制方式下存在换相误差时非换相相电流的精确表达式。针对PAM调制方式下高速无刷电机的换相过程持续时间极短,提出一种校正无位置换相信号误差的新型闭环控制方法,以换相前后30°范围内非换相相电流积分相等为目标,将换相前后非换相相电流积分差值作为反馈量,通过PI调节来自动校正换相信号的相位,采用基于‘90?α’与‘150?α’最优滞环切换的换向策略保证相位可靠校正。实验验证了该闭环校正策略在32 000r/min范围内能够对换相信号误差进行实时补偿。

This paper analyzes the exact expression of the non-commutation phase current considering the commutation error in PAM modulation mode of high-speed magnetically suspended brushless DC motor based on the line-to-line back-EMFs and points out that the commutation process of high-speed motor is very short.Then this paper proposes a new closed loop control method to correct the commutation error according to this conclusion.The method takes the equivalent phase current integration of non-commutation phase within the range of 30° before and after the commutation as the target and takes the phase current integration difference of non-commutation phase as the feedback amount,and corrects the commutation error automatically through the PI regulator.Applying the optimal hysteresis transition between ‘90-α’ and ‘150-α’ ensures the reliable correction of the commutation error.The experimental results show that this closed loop commutation correction strategy realizes the real-time compensation for the commutation error within the scope of 3 2000r/min.