Sensorless sliding mode control of induction motor drives

This paper demonstrates that invariant regulator and superior servo performance can be obtained, compared to fixed gain controllers, through sliding mode speed control of a decoupled induction machine. The speed control scheme consists of a standard indirect vector control implementation for torque control, with a sliding mode speed controller. Assuming the bounds on the parameter variations are known, the control law is derived. The chattering of single component sliding mode controller, is eliminated by introducing a boundary layer. The performance of single component sliding mode controller with boundary layer is further improved by dual component sliding mode controller. Robustness to variation of parameters, like rotor resistance and moment of inertia are demonstrated through simulation. Results are compared with fixed gain controllers. A speed estimation algorithm is implemented and used in the sliding mode control scheme. Sensorless sliding mode control is found to be superior to fixed gain control. Further, it is established through tests that, dual component sliding mode control performs better than single component sliding mode control.