Optimized High Frequency Signal Injection Based Permanent Magnet Synchronous Motor Rotor Position Estimation Applied to Washing Machines

Problem statement: This study investigates a novel optimized scheme of a High Frequency Signal Injection (HFSI) based sensor less technique in order to carry out a precise and robust rotor position error estimation of a Permanent Magnet Synchronous Motor (PMSM) drive designed for washing machines. The study was carried out for standstill condition, where precise position information was required for this application. Approach: In order to get rotor position error information, a PMSM high frequency model was considered in the estimated rotor reference frame (d,q). The impact of the HFSI technique parameters choice on the PMSM rotor position estimation performance was studied and experimentally tested, under various injection conditions. Results: The experimental results show that the amplitude of the high frequency current, resulting from injection, was not significant to carry out high performance rotor position estimation. In order to improve rotor position estimation performance and robustness, a modified demodulation of the high frequency current resulting from injection was proposed by using a high pass filter amplifier applied to PMSM measured currents. The novel proposed rotor position error extraction scheme was implemented on a dsPIC30F6010A and was experimentally validated on a 1kW washing salient pole PMSM. Conclusion: This study presents an improved high frequency voltage injection based sensor less control for Permanent Magnet Synchronous Motor (PMSM) designed for washing machines. The optimal parameters choice of the HFSI technique and the use of a high pass filter amplifier have allowed to take the most of the high frequency injected signal for extracting the rotor position error at standstill, compared to a conventional scheme.