Sensorless control of PMSM based on a high-frequency injection using a complex-valued filter

The traditional high-frequency (HF) injection-based sensorless control uses a band-pass filter (BPF) and a low-pass filter (LPF) for position signal demodulation, however, their narrow bandwidth limits the convergence rate of the sensorless control and can result in instability issue. In this work, a complex-valued filter (CVF) is proposed to demodulate the critical signal for position estimation, which features no phase delay and can replace LPF and BPF. Along this way, a phase-locked loop with selective harmonic compensation (SHC-PLL) is suggested to cancel the HF harmonics in the estimated speed, which further improves the estimation precision of the position. Finally, the proposed method is verified by the experimental results.