EMC Modelling of IGBT-Based Voltage Source Converters: High-Frequency Behavior, Parasitic Characterization and Simulation Methodology

Sammanfattning

This thesis investigates model-based electromagnetic comparability (EMC) of an IGBT-based two-level voltage source converter (VSC). The main focus lies on common-mode and differential-mode behaviour through conducted electromagnetic interference (EMI). The study centres around the Active Dynamic Filter P25 developed by Comsys AB, which serves as the converter under test (CUT). Conducted emissions caused by parasitic elements are analysed through a combined approach of measurements and simulations. The work presents a methodology for characterising parasitic components in both active and passive circuit elements. Detailed impedance measurements, including the junction capacitances of IGBT modules under bias, are performed to capture their frequency-dependent behaviour. The impact of parasitic couplings, such as those between heatsinks and ground, is investigated. Simulations are carried out using MATLAB/Simulink, with models incorporating measured parasitic parameters. The results demonstrate a clear correlation between modelled and measured EMI phenomena, reaching the low MHz range. A workflow is proposed for EMC evaluation during early product development. This work provides a foundation for extending EMC modelling into higher frequency domains and proposes a methodology for EMI analysis in VSC-based systems. The findings and knowledge gained support more reliable EMC simulations that can be used for future research.