Variable gain PI controller design for speed control and rotor resistance estimation of an indirect vector controlled induction machine drive

This paper presents an original variable gain PI (VGPI) controller for speed control and rotor resistance estimation of an indirect vector controlled (IVC) induction motor drive. First, a VGPI speed controller is designed. Its simulated performances in speed control and rotor resistance estimation are compared to those of a classical PI controller. Simulation of the IVC induction motor drive using VGPI for speed control shows promising results. The motor reaches the reference speed rapidly and without overshoot, trapezoidal commands under no load are tracked with zero steady state error and almost no overshoot, load disturbances are rapidly rejected and variations of some of the motor parameters are fairly well dealt with. For rotor resistance estimation, the variation of the integrator gain from zero to a terminal value results in the elimination of the transient state estimation error. The proposed VGPI resistance estimator provides excellent tracking performance.