Model-Based SMC Strategy for Speed Control with a sensorless Load-Torque SM Observer: Analysis and Experimental Validation Using an IM

Abstract

This article investigates speed control of AC motors under load-torque uncertainty by employing the model-based sliding-mode control (MBSMC). Since using sensors reduces the reliability of the control and increasing the cost, a sensorless sliding-mode observer (SMO) is proposed to overcome the uncertainty of load-torque. Although the suggested MBSMC is applicable to AC motor drive in general, here the proposed controller is applied to an induction motor (IM). The new model-based SMC is used to control the speed of the motor using the dynamic equations describing motor speed. Both reaching-phase and sliding-phase are in place to move the control signal from an arbitrary location to the sliding surface, and then towards the equilibrium point. The aims are reduction of chattering as well as improving transient condition. First, detailed theoretical analysis are introduced that include modeling, control, stability proof as well as simulations. Then, an implemented 1.5 kVA IM test setup was used to confirm theoretical studies. Experimental results show that the suggested control strategy (the MBSMC with the sliding-mode load-torque observer) is stable, minimizes chattering of the current as well as improving overall performance metrics.