Adaptive Filter Based Position Estimation Accuracy Improvement for Sensorless Control of SPMSM at Zero and Low Speed Regions

In this article, dual second order generalized integrator (DSOGI) based rotating high frequency voltage injection method is proposed for sensorless control of surface-mounted permanent magnet synchronous motor (SPMSM) at zero and low speed regions. Compared with the conventional band pass filter (BPF) and high pass filter (HPF), DSOGI are proposed to suppress the position estimation error due to the phase shift in the high frequency (HF) demodulation process. The first SOGI serves as an adaptive BPF and it is used to separate the HF current and fundamental current in the stationary reference frame. Compared with the conventional BPF, the resonance frequency of the SOGI can be adaptively adjusted according to the rotor speed. Therefore, the phase shift of BPF is eliminated, especially with the increasing of rotor speed. The second SOGI serves as a band stop filter (BSF) and it is used to extract the negative sequence component of HF current that contains the rotor position information. Finally, the conventional BPF and HPF are removed and the accuracy of rotor position estimation is improved. The experimental data validates the effectiveness of the proposed method.