Simulation of inverter-fed induction motor drives with pulse-width modulation by a time-stepping coupled finite element-flux linkage-based state space model

In this paper, a detailed description of the simulation of inverter-fed induction motors in adjustable speed drives by a Time-Stepping flux linkage-based Coupled Finite Element/State-Space model for the computation of the drive performance is presented and verified experimentally. The flux linkage-based State-Space model is iteratively coupled to a 2D Time-Stepping Finite Element model. The iterative nature of the coupling between these two models facilitates rigorous modeling of the comprehensive impact of inherent space harmonics due to geometries and motor magnetics and time harmonics resulting from the electronic switching of inverters, as well as effects of the synergistic interaction between these time and space harmonics. The State-Space model includes no frame of reference transformation in so far as the flux linkages, currents or voltages. This implies that the State-Space model directly couples the motor to its power electronic controller in one formulation and the natural variables (voltages and currents) are directly involved in the formulation and computation. Finally, results of motor drive performance simulations and corresponding test results for a six-switch inverter with 180 degrees e duty cycle for each switch and a six-switch inverter with Pulse-Width Modulation are given with excellent test result correlations, respectively.