Transient analysis of PWM inverter-fed AC motor drives using finite element method coupling with external circuit model

This paper presents a method for an accurate computation of the dynamic behavior of PWM inverter-fed ac motor drives with voltage sources as excitations. The method is based on the 2D finite element method coupling with external circuit models, together with the simultaneous simulation of the motion of the rotor system. Attention is focused on the special issues, such as the best approach to take into account the motion between the stator and the rotor, the skin effect and the numerical oscillation which arises from the (high frequency) step changes of the output voltages of the inverter, when finite element analysis is used. In this paper the interpolating moving boundary is introduced when considering the relative motion between the stator and the rotor, and the numerical critical damping method is used to suppress the numerical oscillation which may occur in numerical simulations. The computed results of a PWM inverter-fed motor drive system is used to validate the proposed method.