A Closed-Loop PMSM Sensorless Control Based on the Machine Acoustic Noise

In this article, a novel sensorless control for permanent magnet synchronous machine (PMSM) using its radiated acoustic noise is proposed in which a high-frequency voltage signal is superimposed upon the fundamental excitation and the machine response to such excitation is studied. First, the analytical equations describing the field formation within the airgap leading to the generation of radial forces and acoustic noise are extensively investigated. In the next step, resulting harmonics in the acoustic noise waveform caused by the injected signals are predicted. Then it is experimentally verified that, depending on the machine structure, there will be some distinctive sidebands around the injected frequency directly related to the fundamental synchronous frequency. Acoustic noise waveform is highly distorted and sensitive to the environment; so a proposed four-stage signal processing algorithm containing two self-adaptive band-pass filters are used to safeguard the signal against unwanted distortions and flawlessly extract the rotor position information. Robustness and effectiveness of this method are verified experimentally in various operating conditions.