Pseudo-Random Frequency Pulse Voltage Injection for Sensorless IPMSM Drives at Low Speeds

Abstract

High frequency (HF) signal injection is commonly used in sensorless permanent magnet synchronous motor (PMSM) drives at low speeds and standstill. However, the extra acoustic noises caused by additional signal injection impose restrictions on its further applications. To address this issue, a pseudo-random frequency pulse voltage injection scheme is proposed for sensorless PMSM drives at low speeds. Compared with the pseudo-random signal injection, the proposed pseudo-random frequency pulse voltage injection scheme with pulse width adjustment can make all the discrete harmonics in the noise spectrum disappear, thus achieving effective noise attenuation. The signal injection design is performed via current power spectral density (PSD) analysis. According to the form of the injected signals, the signal demodulation procedure is designed to obtain estimated rotor position. The validity of the proposed scheme is verified on 2.2-kW IPMSM platform.