Improved Sensorless Control Method for SPMSMs by High Frequency Pulsating Square-Wave Voltage Injection Using only Complex-Coefficient Filter

This paper proposes an improved sensorless control method for surface-mounted permanent magnet synchronous motors (SPMSMs) by high-frequency (HF) pulsating square-wave voltage injection method based on complex-coefficient filter (CCF). In the whole signal process procedure, only CCF is used so as to simplify the control system and improve the dynamic performance. Comparing to the traditional signal processing approach with low pass filter, the proposed method can significantly reduce the phase delay. Besides, this paper proposes a new method to error signal derivation under the αβ stationary reference frame when adopting HF pulsating square-wave voltage injection method, which will be effective when considering cross-saturation effects as well. This provides a novel compensation idea for position estimation error caused by cross-saturation effects. Furthermore, in order to enhance the HF signal injection performance on SPMSMs, a simple d-axis current injection method is used in the paper. Finally, the validity of the proposed method is verified by experiments on a SPMSM platform.