Enhanced sensorless control of SPMSM based on Stationary Reference Frame High-Frequency Pulsating Signal injection

In this work, an enhanced sensorless control of Surface-mounted PMSM is proposed based on the Stationary Reference Frame High-Frequency Pulsating Signal (SRF-HFPS) injection method. Due to the fact that the saliency of a normal SPMSM is usually weaker than that of an Interior PMSM, the SPMSM is seen as a non-salient machine whose sensorless capability is greatly limited. As a result, the sensorless control for the SPMSM is investigated in this work. In the existing SRF-HFPS method, only an inherent DC offset showing in α/β-axis currents is eliminated. However, multiple saliencies (AC harmonic) existing extensively in the AC machines should be considered and decoupled as well. Therefore, in this work, a high pass filter and an adaptive notch filter are adopted for the DC and AC harmonic decoupling, respectively. To meet the minimum requirement of saliency intensity, the weak spacial saliency needs to be enhanced. Thus, a d-axis current planning method is designed accordingly to expand the feasible area of the saliency tracking based sensorless control method. The effectiveness of proposed improvements has been verified by experimental results.