Flux Observer Based on Frequency-Adaptive Phase Compensation for PMSM Sensorless Control

There are problems of initial value and DC bias in the flux observer of permanent magnet synchronous motor (PMSM), which will lead to errors in the estimated electrical angle. Based on the flux observer combined with high-pass filter (HPF), a new frequency-adaptive phase compensation (FAPC) scheme is proposed in this paper. The cut-off frequency of HPF is dynamically adjusted according to the electric angular frequency of the rotor, so that the required angle compensation of the filtered signal is kept at +45 or -45 degrees, which simplifies the algorithm implementation. Experiments including steady-state test and rotation switching test are performed, which can verify the effectiveness of the proposed method.