Characterization of induction motors in adjustable speed drives using a time-stepping coupled finite element state space method including experimental validation

This paper describes how a comprehensive time-stepping coupled finite element phase flux linkage-based state-space modeling approach can be used for characterization of induction motors in adjustable speed drives. The model implemented the faster indirect and iterative coupling approach based on the curl-curl nondiffusion equation rather than the direct coupling approach which is based on the curl-curl diffusion equation. The model presented in this paper is capable of rigorously modeling the effects of magnetic nonlinearities and space harmonics due to the machine magnetic circuits' topology and winding layouts, time harmonics resulting from electronic switching of inverters as well as the synergistic interaction between these time and space harmonics. This is accomplished through the successive updating of the machine parameters throughout the iterative process. The results of motor drive performance simulations and corresponding experimental test results are given here with excellent correlations. This includes sinusoidal excitation, and six-switch inverter excitation with pulse-width modulation switching pattern, respectively.