Output Feedback Controller of Electric Drive based Variable Speed Induction Motors

Abstract

The main purpose of this study is design of output feedback controller based sampled – output full order high gain observer and its application on variable speed nonlinear model of induction machine drives. The proposed new state observer over standard ones is robust with respect to sampling time schedule and unknown external load torque profile to the observer. Only two of the electrical state variables are supposed to be accessible, which are stator voltages and discrete time mode stator currents. As a matter of fact, this study presents an observability analysis of the induction machine, leading to an adequate observability condition. Nonlinear output feedback control design technique ensures fast tracking time response and exponential convergence of the observation error with time progressive. The stability convergence of the proposed state observer is formally analyzed using tools of Lyapunov stability theory. The simulation results using MATLAB environments are given to support the main results and ensure the efficiency of the proposed strategy applied on 7.5 kW AC machine based on time varying gain inside the observer structure. It plays an active role in increasing the sampling time interval compared to fixed gain starting from 1.5ms upto 4ms