Hybrid Pseudorandom Signal Injection for Position Sensorless SynRM Drives with Acoustic Noise Reduction

The extra acoustic noise caused by the high-frequency (HF) signal injection imposes restrictions on its extensive applications for sensorless synchronous reluctance motor (SynRM) drives. To attenuate the undesired acoustic noise further, a hybrid pseudorandom (PR) signal injection scheme is proposed in this article. The hybrid PR signal injection is implemented by injecting square wave signals chosen in a random manner from a set of signals having either different frequencies or phases from each other. The optimal assembly of hybrid PR signals is designed via current power spectral density (PSD) analysis, aiming at reducing acoustic noise as much as possible. In this way, the proposed scheme achieves success in a massive acoustic noise reduction by means of completely eliminating the discrete harmonics of the current PSD and distributing the current PSD to a wider range. Besides, the low-pass filters used to separate the fundamental frequency component from injected HF components of currents could be eliminated because no discrete harmonics at injected frequencies exist with the proposed hybrid PR signal injection. The validity and superiority of the proposed sensorless control scheme are verified on a 3-kW position sensorless SynRM drive platform.