Comparison performance between sliding mode control and nonlinear control, application to induction motor

A squirrel cage induction motor has been the workhorse in industry for variable speed applications in a wide power range that covers from fractional horsepower to multi megawatts. But the control and estimation of ac drives in general are considerably more complex than those of dc drives. The advent of vector control techniques has partially solved induction motor control problems. However, these techniques are very sensitive to the variation of motor parameters, result in an undesirable coupling between the flux and the torque of the machine, and loss of dynamic performance. To solve these problems this paper presents a synthesis of two control strategies, for controlling speed and rotor flux of induction motor (IM) via nonlinear control (NLC) and sliding mode control (SMC). Computer simulations are carried out to show the robustness of the proposed method against rotor resistance and load torque variations. The performance of SMC has been successfully compared with nonlinear control.