Simple Prediction Method for Impacts of Switching Characteristics on EMI Noise of a Three-phase PWM Inverter

This article proposes a simple prediction method for impacts of switching characteristics on electromagnetic interference (EMI) noise of a three-phase pulse width modulated (PWM) inverter. In this method, target EMI noises are obtained by multiplying transfer functions of noise propagation paths and frequency spectra converted from time-domain switching voltage and current waveforms of a power device as noise sources. This method has two key features. First, it emulates the time domain scanning method in compliance with CISPR16-1-1, enabling predictions of peak, quasi-peak (QP) and average value of EMI noise. Second, it incorporates the dependence of the switching waveforms on output current into the EMI noise prediction. Finally, this article presents comparisons between measurement and prediction results of radiated EMI noise generated from a three-phase motor drive system with a three-phase PWM inverter, showing good agreement, respectively.