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

Abstract

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.

Popular Abstract

From Sparks to Silence: Modelling Electrical Noise in Power Filters

Power converters are vital to modern life—but they can cause electronic “noise” that disturbs the converter or other equipment. This thesis shows how to predict and reduce this interference before the product is even built.

Today’s power systems are full of electronics that switch extremely fast—turning currents on and off thousands of times per second. While this is great for efficiency, it also creates unintended electromagnetic signals, or interference, that can spread to nearby equipment and cause malfunctions. This is especially important for companies like Comsys AB, which develop products to improve power quality in sensitive industrial environments.

This thesis explores how such interference arises inside one of Comsys’s real products, the ADF P25—an "active power filter" that helps clean up distorted currents in the grid. The problem is that the very device designed to reduce disturbance can itself create new kinds of interference. Why? Because when fast-switching components are placed close together, they create tiny unwanted capacitors and inductors. These invisible components—called parasitics—act like hidden antennas inside the device.

The goal of the project was to understand how this interference works and to develop a reliable way to simulate it early in the design phase. By measuring these parasitic effects in the lab and recreating them in detailed computer simulations, the authors succeeded in matching the predicted interference with what was measured in real life. That’s a big deal—because it allows engineers to “see into the future” and fix potential issues before they arise.

This research resulted in a suggested workflow for how to simulate and address electromagnetic compatibility (EMC) in future converter designs. The benefits? Fewer design mistakes, faster development, and products that are more likely to pass strict international tests on the first try.

One fun detail: part of the work involved opening up and dissecting real power modules—cutting microscopic wires and injecting test signals—to understand how the internal layout affects the interference. It's hands-on detective work for the invisible world of high-frequency noise.

Although the study focused on one specific filter, the methods can be applied to a wide range of power electronic devices. This contributes to the broader goal of building smarter, cleaner, and more compatible electronics for a connected world.

• author: Raväng, Linus and Siwerson, Oskar
• supervisor: Hannes Bydén
• organization: Department of Biomedical Engineering
• course: BMEM05 20251
• year: 2025
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Active Power Filter, EMC, EMI, simulation, power electronics, IGBT, junction capacitances, parasitics
• language: English
• additional info: 2025-16
• id: 9206280
• date added to LUP: 2025-06-30 12:34:28
• date last changed: 2025-06-30 12:34:28