Comparative Investigation of Pseudorandom High-Frequency Signal Injection Schemes for Sensorless IPMSM Drives

The fixed-frequency signal is employed in conventional high-frequency (HF) signal injection-based sensorless control schemes for interior permanent magnet synchronous motor (IPMSM) drives, which causes significant electromagnetic and acoustic noises. In order to diminish the additional noises, a novel pseudorandom HF (PRHF) signal injection method is investigated in this paper. Comparative analysis of the power spectra density of the induced HF currents is carried out among three different schemes: fixed-frequency HF, full-period-switch (FPS) PRHF, and half-period-switch (HPS) PRHF square-wave voltage injection. The principles and the spectral characteristics of the three PRHF injection schemes are described. Both theoretical analysis and experimental results are provided, which can agree with each other well. A theoretical basis of frequency determination is presented. Comparison of the spectral performance shows that the HPS-PRHF scheme has continuous spectra and the electromagnetic and acoustic noises can be suppressed significantly. The method is verified via a 2.2-kW IPMSM drive platform.