Equivalent-Signal-Based Sliding Mode Speed MRAS-Type Estimator for Induction Motor Drive Stable in the Regenerating Mode

The paper presents a new speed estimator designed for sensorless induction motor drives. The proposed sliding-mode estimation algorithm is a model reference adaptive system-type estimator. Its reference model is the induction motor, while both the stator current and rotor flux estimators create the adaptive system. The estimator uses a sliding mode technique in order to ensure robustness and simple implementation. The algorithm is based on the equivalent signal technique which allows us to significantly decrease chattering, while simultaneously retaining the properties of the sliding mode estimator. Additionally, the estimator is extended with an auxiliary variable which allows us to improve the stability of the estimation in regenerating mode operation. The proposed estimator is verified using extended simulation and experimental tests.