Speed-sensorless Control of Induction Motor Based on a Multi-weighted Hybrid Model Rotor Flux Observer

Rotor flux is the key to achieving speed-sensorless control of induction motors (IMs). Although the Gopinath model rotor flux observer has received considerable attention, it has some drawbacks, such as parameter sensitivity in the low- and medium-speed regions. To overcome these drawbacks, an improved rotor flux observer with enhanced parameter robustness is proposed to realize the speed-sensorless control of IMs. In this study, the main drawbacks of the Gopinath observer are analyzed, and the design principles of the characteristic function are deduced for the first time. An improved multi-weighted hybrid model rotor flux observer is then proposed. After analyzing the parameter sensitivity of the proposed observer in detail, a speed-sensorless control method is designed based on this observer and a phase-locked loop. Comparative experimental studies demonstrate the effectiveness of the proposed rotor flux observer and speed-sensorless control method.