Nonlinear parameter estimation for cycloconverter-fed induction motor drives

A microprocessor-based scheme for the parameter estimation of cycloconverter-fed induction motors is presented. The method is based on the fundamental equivalent circuit including temperature-dependent resistances and a nonlinear inductance. The difficulty of parameter estimation in the presence of nonlinearity can be overcome by a nonlinear formulation. An iterative algorithm for solving the nonlinear equations is developed. The algorithm consists of an approximate evaluation of the working point and a refined estimation of the induction motor parameters. Simulation results show the validity of the proposed method, which gives effective indentification of the parameters over a wide operating range of the motor despite the effects of magnetic saturation, waveform ripples, and noise contamination of the measurements