Random Dual-Interval High-Frequency Square-Wave Voltage Injection Based Sensorless Control of IPMSM Drives for Noise Reduction

As a sensorless control method of interior permanent magnet synchronous motors (IPMSMs) at zero and low speeds, high-frequency square-wave voltage injection (HFSVI) method faces the challenge of producing harsh audible noise. To address this issue, a novel random dual-interval high-frequency square-wave voltage injection (RDI-HFSVI) method is proposed in this paper. Firstly, the mechanism of HFSVI with random switching frequency is analyzed. To broaden the spectrum of induced currents effectively, a novel injected form where the frequency of injected voltage is extended to two more dispersed ranges is proposed. And the switching frequency varies randomly to eliminate the harmonics caused by pulse width modulation (PWM). Secondly, a signal demodulation strategy matched with the proposed injected form is designed, with considering the time-delay compensation. Furthermore, the power spectra density (PSD) analysis of proposed RDI-HFSVI method is carried out, which indicates that RDI-HFSVI can eliminate all discrete harmonics and disperse spectrum energy effectively. Finally, experimental results on a 750 W IPMSM drive platform demonstrate that the proposed method significantly reduces noise while maintaining the estimation accuracy of rotor position.