PWM switching frequency signal injection sensorless method in IPMSM

This paper describes how to extract the rotor position information using a PWM switching frequency voltage signal injection without position sensor in Interior Permanent Magnet Synchronous Machine (IPMSM). The frequency of injected voltage signal is increased to PWM switching frequency, and the dynamics of the sensorless control can be improved. Compared to conventional heterodyning process, the proposed method is simple to implement and appropriate for PWM switching frequency signal injection. The high frequency voltage signal can be injected in the stationary reference frame or in the estimated rotor reference frame. In this paper, two sensorless methods are proposed according to the injection reference frame. To verify the proposed methods, 5kHz voltage signal injection with 5kHz PWM switching frequency inverter system in both reference frames were implemented. The experimental results confirm the effectiveness of the proposed method.