基于脉幅调制的超高速无刷直流电机过零点检测补偿策略

Proposed Compensation Strategy for Ultra-High Speed Brushless DC Motor Based on Pulse Amplitude Modulation Zero Crossing Detection Yu Yue1 Li

超高速无刷直流电机广泛应用于超高速空压机、晶圆切割、飞轮储能等系统。针对超高速无刷直流电机控制中的三相绕组不完全对称和参考零点不确定偏移导致的失步问题,该文以脉幅调制控制器为基础,通过对非理想电机的研究,建立过零点抗扰动的模型,提出一种综合考虑不平衡过零点和不对称过零点补偿的改进控制策略,建立适用于三种非理想过零点模型的基础延迟时间择优策略的数学模型和换向时间补偿函数。同时,在不平衡不对称过零点扰动存在的前提下,考虑负载变化等因素引起的换相误差并提出相应的变速误差补偿策略。实验结果表明,改进控制策略可以有效减小无刷直流电机的换相误差,显著地提高电机换相的精度进而提高其运行速度上限,为无速度传感器超高速无刷直流电机稳定运行提供了一定的理论基础。

The ultra-high-speed brushless DC motor(BLDCM)finds extensive application in various systems,including ultra-high-speed air compressors,silicon wafer cutting,and flywheel energy storage.However,controlling ultra-high-speed BLDCM presents several challenges stemming from the incomplete symmetry of the three-phase windings and the uncertainty associated with reference zero-offset,often leading to stalling issues.Therefore,it is necessary to design different commutation delay setting methods and put forward a comprehensive solution.First,based on pulse amplitude modulation control,a fundamental disturbance model for zero-crossing point(ZCP)resilience is established by investigating non-ideal motors.The influence of the reference zero offsets of ZCP and the incomplete spatial position symmetry of the stator windings on the ZCP position distribution in one cycle is analyzed.Then,the influence of their coexistence on the ZCP position distribution in one cycle is analyzed.An improved control strategy is proposed to address the compensation for unbalanced and asymmetric ZCPs.The proposed method mainly uses the ZCP interval law in the previous cycle to offset the interference of non-ideal factors.It selects the optimal setting of the base delay time through the proposed non-ideal situation judgment method.At the same time,the derived function of electrical angle to time is derived for each non-ideal case to accurately compensate for the phase shift error in the motor control process.Furthermore,the commutation errors caused by speed changes under varying loads are considered under unbalanced and asymmetric ZCP disturbances.Different from the traditional use of the first two ZCP intervals,the first seven ZCP intervals are used for compensation,and the internal cancellation of ZCP disturbance within one cycle is used to eliminate the influence of ZCP disturbance on variable speed commutation error compensation.A compensation method for variable velocity commutation error is proposed based on unbalanced and asymmetric ZCP disturbance.Finally,the phase shift caused by the low-pass filter under ultra-high-speed and the diode continuous current under heavy loads are considered.The corresponding solutions and parameter selection rules are given.The experimental results describe the performance of the new commutation delay setting method.Compared with the traditional method,the bus current ripple is reduced by 50%,and the phase current ripple is reduced by 22.5%.By compensating the phase shift factor of the low-pass filter and applying the proposed variable speed compensation strategy,the commutation error can be controlled to 1.81 electrical angle,and the ultra-high speed of 230 kr/min can be achieved.