An Intuitive and Accurate EMI Model for a Modular Multilevel Converter

Modular multilevel converter (MMC) has numerous sub-modules (SMs) that are complex electromagnetic interference (EMI) sources. It poses a challenge on the EMI analysis of MMC. Motivated by the challenge, this article presents an intuitive and accurate EMI model of MMC based on the superposition theorem. The stray parameters of MMC system are extracted to characterize the high-frequency characteristics of the circuit. By modeling the SMs as individual EMI sources, an EMI equivalent circuit is derived which can intuitively tell the conducted EMI principles of MMC. The EMI model based on the EMI equivalent circuit can accurately predict the EMI results of MMC without a great deal of calculation. Simulation results verify the effectiveness and validity of the proposed EMI model.