High Frequency Square Wave Voltage Injection Based Inductance Identification for PMSM Sensorless Control

The sensorless control performance of permanent magnet synchronous motor (PMSM) is greatly degraded by inductance mismatch in the medium and high speed region. Therefore, an on-line inductance identification method based on high-frequency (HF) square wave voltage injection, which can be embedded in PMSM sensorless control, is proposed. By injecting the high-frequency square wave voltage in dq-axis, the HF current response is obtained, and the envelope of HF current is extracted. On this basis, an inductance identification algorithm is designed. The estimated inductance values are used to update the values in flux observer. This method is applicable to both surface mounted and interior rotor structures. The simulation results indicate that the proposed method can accurately identify the inductance value and improve the sensorless performance.