Enhanced Offline Identification for Induction Motors at Standstill: Overcoming Nonlinearity and Enabling Multimode Cooperation

Accurate electrical parameters are essential for high-performance control of induction motors (IM). However, conventional parameter identification methods suffer from limited accuracy and adaptability due to motor structural asymmetry, inverter nonlinearity, and the time-varying characteristic of IM parameters. To address these issues, this paper proposes a standstill identification method considering the nonlinearity effect, which employs the phase-specific multi-frequency current signal injection. The studied strategy addresses three key challenges in the existing schemes. First, an adaptive voltage error elimination method is introduced to suppress the effects of inverter nonlinearity. Second, a multi-frequency excitation signal injection strategy is developed to decouple the identification of IM parameters. Third, a DC-biased AC excitation scheme is incorporated to accurately identify mutual inductance under different magnetic saturation conditions, thereby enabling multi-mode cooperative control. Finally, the experimental validation on a 2.2-kW IM drive system shows the accuracy and feasibility of the studied method. This paper is accompanied by a video that demonstrates the entire process of the proposed parameter identification method.