Parameter sensitivity of full-order flux observers for induction motors

Abstract

This paper deals with flux estimation for induction motor drives. The equations of the parameter-sensitivity of both the rotor flux estimation and the torque production are derived for a full-order flux observer. Based on the parameter sensitivity analysis, practical methods of designing robust observer gains combining the current model and the voltage model are proposed. The proposed gains are easy to tune and lead to a simple observer structure. Experimental results show that for inaccurate parameter estimates, both the steady-state and dynamic errors in the produced torque are small as compared to the current model. Furthermore, high-speed operation is possible without modelling the magnetic saturation even if motor parameters are highly erroneous.