Simultaneous Online Inductance Identification and Position Sensorless for PMSM at Low Speed Based on Arbitrary Amplitude Square-Wave Injection

High-frequency injection is widely adopted for inductance identification or position sensorless control, but few studies have achieved both functions at the same time. In this paper, both functions are achieved simultaneously using the same injection sequence. This paper analyzes the features of the conventional inductive reactance model with cross-coupling effects. Then, the high-frequency square-wave voltage with arbitrary amplitude is presented. Later, the separation paradigm for self-excited and coupled-excited currents is proposed, alongside an online cross-coupling angle calculation method. To achieve simultaneous online inductance identification and position estimation, the sensorless control object is corrected using a look-up table. As a result, the dq-axis incremental inductances and cross-coupling incremental inductance estimators are performed without offline cross-coupling angle calibration values. The proposed method is validated on both the simulation platform and the drive motor bench. Different operating conditions illustrate the effectiveness of inductance identification and sensorless control.