Sensorless sliding-mode control of induction motors using operating condition dependent models

A sensorless torque control system for induction motors is developed. The system allows for fast and precise torque tracking over a wide range of speed. The paper also presents the identification and parameter estimation of an induction motor model with parameters varying as functions of the operating conditions encountered in hybrid electric vehicles applications. An adaptive sliding mode speed-flux observer is developed and a cascade of discrete time sliding mode controllers is used for flux and current control. Simulation and experimental results prove the validity of the approach.