Robust Control of Vector-Controlled Induction Motor Drives

The paper presents an original methodology to solve the problems of vector control degradation, due to the changes of motor electrical parameters, and the inadequate rejection of external disturbances and load variations, in induction motor drives. The solution of the first problem is reached by using a new algorithm, based on the extended Kalman filter (EKF) theory, for the contemporaneous estimation of rotor flux components and motor electrical parameters. Insensitivity to external disturbances and load variations is obtained by designing two fuzzy logic controllers (FLC) for the rotor flux and speed regulation loops. The inherent non-linear characteristics of the fuzzy controllers make it possible to obtain fast and accurate tracking of rotor flux and speed references in presence of varying load conditions, changes of mechanical parameters, process nonlinearities, and inaccuracy in the process modelling.