Modelling an AC motor with high accuracy in a wide frequency range

This study presents a practical method to construct a high-frequency equivalent circuit model for AC motors in Spice-like simulation software. This model can be used to analyse the characteristics of the motor and predict the conducted electromagnetic noise in an adjustable speed drive system. The modelling is based on measured data of the impedance and vector fitting technique. The procedure of the modelling is elaborated in this study and verified by comparing simulated data with experimental data on a 200 kW induction motor in the frequency range from 10 kHz to 10 MHz. This modelling method can be extended to model other types of motors irrespective of the power rating of the motors. Applications of the motor modelling to study common mode voltage in the system and current oscillation in motor winding are presented.