Research on Operation Characteristics of Permanent Magnet Synchronous Motor at Zero and Low Speeds Based on Pulse Vibration High-Frequency Injection Method

In order to reduce costs, compress space, and improve system stability under harsh operating conditions, the current vehicle motor drive systems often use position sensorless control methods. However, due to the introduction of filters and the hysteresis of position observers, the position sensorless control has the problem of deteriorating dynamic performance when vehicles start from zero and low speeds or their loads change. Therefore, this article focuses on the problem of position sensorless control applied by permanent magnet synchronous motors when vehicles start and operate at zero and low speed. Combined with high-frequency pulse vibration injection method, the relationship between the types of position observers, parameter selection, and position tracking performance is analyzed and compared. The short-pulse injection method is proposed to locate the initial position of the motor, overcoming the inherent 180° position deviation of pulse vibration high-frequency injections. Subsequently, the impact of the amplitude and frequency of the injected high-frequency signal on the performance of position estimation is focused on. Considering the adverse effects caused by the phase delay of the filter, a design method for filter parameters is proposed to achieve a smooth start and operation of the permanent magnet synchronous motor under position sensorless control. Finally, the rationality of the theoretical analysis and the effectiveness of the adopted methods are fully verified through simulation and experiments.