A Unified Demodulation Method for High-Frequency Signal Injection Based IPMSM Sensorless Control

High-frequency signal injection (HFSI) method is a common control strategy for interior permanent magnet synchronous motor (IPMSM) drives at zero and low speeds. A reasonable demodulation method is the key to successfully extracting the rotor position information. In conventional demodulation methods, the demodulation processes generally need to consider the impact of time-delay effect on demodulation signals. In this letter, a novel unified demodulation method without the demodulation signal is proposed, which is suitable for different injected types. The proposed method can effectively avoid the negative impact caused by the inherent time-delay effect of digital control system. Eventually, the effectiveness of the proposed method is verified on a 750 W IPMSM drive platform.