Research on Multi-convergence Point Problem of Sensorless Control in Induction Motor Based on Z-MRAS

In the speed sensorless control of induction motors (IM), the stability and parameter robustness of sensorless control algorithms have been extensively studied, but few papers focus on the problem of speed convergence errors. Taking into account the strong nonlinear characteristics of induction motors, this paper studies the multiple convergence points in the process of sensorless speed observation based on the impedance model reference adaptive method (Z-MRAS). First, this paper analyzes the mechanism and mathematical expression of multiple convergence points through theoretical derivation. Subsequently, the stability analysis of each convergence point is carried out, and the stability regions of different convergence points are given. Finally, this paper proposes a hybrid speed identification strategy, which can effectively avoid speed convergence errors. The theoretical analysis and identification strategy of this paper have been effectively verified on the MATLAB simulation platform.