Rotating High Frequency Voltage Injection Strategy Considering Time Delay for PMSM Based on Dual Heterodyne Method

The rotating high frequency voltage injection (RHFVI) method is widely used for sensorless control of permanent magnet synchronous motor (PMSM) at low and zero speed. The advantage of this method is that parameters tuning is easy and the convergence is good. However, the accuracy of rotor position estimation is degraded due to time delay in the high frequency (HF) current demodulation process, especially with the increasing of the rotor speed. Aimed at this issue, dual heterodyne method based RHFVI strategy is proposed to improve the sensorless performance of PMSM in this paper. Compared with the conventional method, the HF voltage is still injected into the stationary reference frame, however, the rotor position is obtained based on the HF current in the estimated synchronous rotating reference frame. Both the positive and negative sequence component of the HF current are utilized for rotor position estimation by the dual heterodyne method. Position error due to the time delay is compensated and the accuracy of rotor position estimation is improved. In the experimental part, one PMSM is tested to verify the effectiveness of the proposed method.