Noise-Source Model for Frequency-Domain EMI Simulation of a Single-Phased Power Circuit

Abstract

In recent years, power electronic converters have been downsized significantly by high-density packaging techniques. As a result, parasitic couplings between power electronic components have become larger. For the prediction of electromagnetic interference (EMI) noise considering such couplings, a 3-D electromagnetic simulation is more suitable than a circuit simulation using a huge number of parasitic models. The most-practical electromagnetic simulation method is the finite element method, which is based on a frequency domain. The switching noise must be modeled in the frequency domain for an EMI noise simulation. In this article, we propose a new noise-source model for a frequency-domain EMI noise simulation. We modeled a transistor and a freewheeling diode by voltage and current sources based on three model topologies: transistor-OFF-diode-ON topology (OFF-topology); transistor-ON-diode-OFF topology (ON-topology); and transistor-on-diode-ON topology (recovery topology). We also used OFF-topology to simulate the turn-OFF EMI noise as caused by the turning-OFF of a transistor. Meanwhile, we used a combination of ON-topology and recovery topology to simulate the turn-ON EMI noise including recovery noise as caused by the turning-ON of a transistor. After introducing the details of the model, we compared the measured and simulated results so as to show the validity of the model.