Compensation of Zero-Current Clamping Effects for Sensorless Drives Based on High-Frequency Signal Injection

This paper proposes an on-line compensation strategy of the unwanted disturbance voltage due to the zero current clamping effect for high-frequency-signal-injection based sensorless control schemes. An analytical model is derived which reveals intrinsic characteristics of the zero clamping effect for the high frequency signal injection. The model in this form is subsequently incorporated into the development of a specialized off-line commissioning test to find motor inductances and a voltage distortion factor. From the sensitivity analysis of the effect on the magnetic saturation, it is confirmed that the compensation error due to saturation has little negative impact on the proposed compensation method. The compensation result leads to an accurate position estimate during zero-current clamping region and the proposed scheme does not rely on a complicated look-up table. Experiments demonstrate the superiority of the proposed method in suppressing the voltage distortions caused by the zero-current clamping effect