Frequency-Domain EMI Simulation of Power Electronic Converter with Voltage-Source and Current-Source Noise Models

Abstract

The electromagnetic interference (EMI) generated by power electronic converters is largely influenced by parasitic inductances and capacitances of the converter. One of the most popular EMI simulation methods that can take account of the parasitic parameters is the three-dimensional electromagnetic simulation by finite element method (FEM). A noise-source model should be given in the frequency domain in comprehensive FEM simulations. However, the internal impedance of the noise source is static in the frequency domain, whereas the transient switching of a power semiconductor changes its internal resistance in the time domain. In this paper, we propose the use of a voltage-source noise model and a current-source noise model to simulate EMI noise with the two components of voltage-dependent noise and current-dependent noise in the frequency domain. In order to simulate voltage-dependent EMI noise, we model the power semiconductor that is turning on by a voltage source, whose internal impedance is low. The voltage-source noise is proportional to the amplitude of the voltage. In order to simulate current-dependent EMI noise, we model the power semiconductor that is turning off by a current source, whose internal impedance is large. The current-source noise is proportional to the amplitude of the current. The measured and simulated conducted EMI agreed very well.