A comprehensive strategy for modelling the conducted EMI of an integrated motor drive in the time domain

Abstract

The paper introduces a comprehensive strategy for modelling the conducted electromagnetic interference (EMI) of a 48 V 11,2 kW permanent magnet motor drive with an integrated three-phase inverter in the time domain to comply with the CISPR 25 standard. The strategy is based on transient electrical simulations using LTspice® and EMI receiver modelling by signal post-processing in MATLAB®. To extract AC lumped component parameters for electrical simulations of the inverter, the Ansys® Q3D Extractor® environment was employed, while the electrical parameters of the motor side were determined from an impedance analyzer measurement. Two distinct transient simulations were performed and compared, namely a static PWM and a Space Vector Pulse Width Modulation (SVPWM) control strategy, where for the latter the simulation time was chosen to capture one electrical revolution of the motor. For the EMI receiver simulation, a digital Short-Time Fourier Transform (STFT) algorithm, compliant with CISPR 16‑1‑1, was implemented. The simulation of one electrical revolution of the motor lasted 43 minutes, resulting in the average spectral deviation between the measured and simulated spectrum bandwidth of 3,33 dBµV and 2,58 dBµV for peak and average detectors, respectively. The introduced strategy proposes a straightforward approach for the extraction of parasitic elements. Furthermore, it ensures accurate EMI prediction without compromising simulation time, which is crucial to stay within the timeframe when developing an automotive product.