A new variable structure control methodology for electrical/mechanical parameter estimation of induction motor

Induction motor parameter estimation is generally needed for such purposes as fault detection and the achievement of high dynamic performance drives. This paper is an attempt to use variable structure control (VSC) methodology for the on-line estimation of several significant mechanical and electrical induction motor parameters. The estimated parameters are rotor resistance, magnetizing inductance, stator resistance and viscous damping coefficient. In this combined control/estimation method, we propose to apply field-oriented control to the non-linear model of induction motor, and then transform the model by input-state linearization into canonical form. Application of variable structure method would then yield desirable parameters whose lower and upper bounds being known. Stability of the closed loop system is studied, and it is shown that the identification algorithm is convergent and the closed loop system is robust to system uncertainties given the switching gain is chosen sufficiently large. Simulation results show that when parameter step changes are applied, favorable motor parameter tracking is made.