Outer sliding mode control loop for induction motor drive with forced dynamics

摘要

For improvement of robustness of the shaft sensorless electrical drives employing induction motors with forced dynamics to parameter uncertainties and external load torque a new control structure is presented. The original forced dynamics control structure consists of the inner loop, which is stator current control loop and the middle loop, which is shaft sensorless speed control loop. This control structure is now completed with the outer loop, based on the sliding mode control principles. The forced dynamic control completed with outer loop, as well as converting the non-linear induction motor into a linear element, offers higher robustness than conventional shaft sensorless speed control methods. Based on feedback linearisation a first order linear closed-loop response to speed demands with a user specified time constant is obtained. Simulation and experimental results presented show good correspondence with theoretical predictions to improve overall IM drive performances.