Parameter Sensitivity Analysis of Flux Observers for Induction Motors

This paper analyzes the effect of the variation of machine parameters on flux observers in the steady-state condition by the frequency-domain method. Both the flux estimation and the torque estimation are evaluated. The frequency response function (FRF) expressed by the ratio of the estimated flux/torque to the corresponding physical one is derived to evaluate the parameter sensitivity. The flux observers investigated in this paper include the open-loop voltage model, the open-loop current model, and three types of closed-loop adaptive flux observers with PI regulator. Computer simulations are conducted to validate the theoretical analysis.