计及中性点电压的无刷直流电机无位置传感器控制

Sensorless BLDC Drive Allowing for Neutral Point Voltage

为解决无刷直流电机在低速状态下检测转子位置的难题,提出了一种新颖的无位置传感器控制方法。该方法基于凸极式永磁无刷直流电机定子绕组电感是转子位置的函数这一特点,采用H_PWM-L_PWM调制方式,通过检测定子绕组中性点电压的波动情况,从而判断通电相的定子绕组自感是否相等,进而推断出反电动势的过零时刻。再借鉴反电动势法的特点,在过零点的基础上滞后30°电角度,即可确定换相时刻,理论推导证明了该方法的正确性。在实验过程中把该方案与霍尔传感器换相的方法进行了对比,验证了这种方法的有效性。

A novel sensorless scheme for brushless DC （BLDC） motor drives is presented in order to solve the problem that it is very difficult to detect the rotor position at low speeds. The method is based on the fact that stator windings inductance of salient BLDC is the function of the rotor position. When the H_PWM-L_PWM modulation mode is adopted for the salient BLDC motor, the fluctuation of neutral point voltage could be used to justify if the self inductance of energized stator windings is equal, from which the zero-cross point of back electromotive force （back-EMF） could be determined. Referring to the back-EMF method, there is offset between zero-cross point of back-EMF and required commutation positions, which must be compensated to ensure efficient and smooth operation of the motor. Theoretical derivation proves this method is correct. In the experimental system, the commutation signal from the proposed method is compared with the signal form Hall sensor and results confirm the validity of the proposed method.