A disturbance rejection approach for the induction motor through observer based Generalized PI control

A field oriented armature input voltage output feedback control approach is proposed for the robust linear controller design on an induction motor. The scheme simultaneously solves an angular velocity reference trajectory tracking task, and a flux magnitude regulation in the presence of arbitrary time varying load torques and unknown nonlinearities. The field oriented input voltage scheme is combined with linear high gain asymptotic observers, of the Generalized Proportional Integral (GPI) type, and linear, active disturbance rejection, output feedback controllers. The linear observers on-line estimate, in a simultaneous manner, the output phase variables and the lumped effects of a) unknown time-varying load torques and unmodeled frictions and b) rather complex state-dependent nonlinearities present in the electric and magnetic circuits. The field oriented part of the scheme uses the classical flux observer, or simulator. The proposed control laws naturally decouple, while linearizing, the extended second order dynamics for the angular velocity and for the squared flux magnitude. The proposed control scheme is here tested on an experimental induction motor set up.