Novel approach to sliding mode control for field oriented induction motor drives

A novel approach to sliding mode control for field oriented induction motor drives is presented. The suggested controller is based on motor model defined in the frame rotating synchronously with rotor flux. To design proposed controller some part of the motor model is selected as control input and it is obtained by employing the errors between reference and measured currents with usage of discrete-time sliding mode approach. The suggested algorithm is used first as current controller for space vector PWM inverter to drive the motor then it is extended to,flux and torque con trol of the motor using two identical sliding surfaces. The last usage of the control algorithm reduces the outer loop, which generally comprises two cascaded controller structures to a single loop, combining current controller and torque/flux controller. Convergence analysis of the controller is derived by Lyapunov stability method. Effectiveness of suggested control scheme is confirmed by computer simulation. The results taken via simulation demonstrated high performance of the control scheme as well as robustness to parameter variations of the system.