High-Frequency Modeling of Permanent Magnet Synchronous Motor Considering Internal Imbalances

In this paper, an accurate high-frequency modeling methodology for a permanent magnet synchronous motor (PMSM) in a vehicular electrical braking system is presented, which is suitable for analyzing various electromagnetic interference problems caused by a motor drive system. The proposed modeling approach is established according to the vector fitting technique and based on the S-parameter measurements of the PMSM. The equivalent circuit model of the PMSM converted from a measured S-parameter matrix can better describe the impedance characteristics of the three-phase PMSM under study compared to the existing equivalent circuit models because the imbalances inside the motor are taken into account in the proposed modeling process. The proposed PMSM model exhibits high accuracy in the range from 100 kHz to 120 MHz in comparison with the common-mode and differential-mode characteristics of the PMSM, which are measured using the conventional setups.