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

High-frequency voltage signal injection (HFSI) is a sensorless control strategy for internal permanent magnet synchronous motors (IPMSMs) at zero and low speeds. A reasonable demodulation method is the key to successfully extracting the rotor position information. In the classical demodulation method, the demodulation signal is designed to extract the position information and must be changed according to different injected signal types. In this paper, a novel unified demodulation method without the demodulation signal is proposed, which is suitable for different injected types. Compared with the existing demodulation methods that do not require demodulation of the signal, the proposed method does not require extra coordinate transformations. Eventually, the effectiveness of the proposed method is verified via Matlab/Simulink.