A Fast EMI Model Based on Equivalent Interference Sources in Medium-Voltage Cascaded H-Bridge System

The rapid switching of high-powered devices within medium-voltage cascaded H-bridge (MVCHB) system can cause significant electromagnetic interference (EMI), potentially affecting the system's safety and reliability. Due to multiple interference sources and complex EMI paths, it is difficult to evaluate the EMI performance of MVCHB system. To solve this problem, this article builds a simplified model to describe the EMI paths within an MVCHB system and proposes an equivalent interference source modeling method based on fitting the voltage waveform of submodules under a wide range of current variations. Then, by cascading submodule interference sources, equivalent interference sources for each phase are obtained. According to the proposed model of EMI paths and equivalent interference sources, the model of MVCHB system is built. An experimental prototype of 10 kV MVCHB system is measured to verify the proposed EMI model of MVCHB system. Based on the EMI model of MVCHB system, the conducted EMI performance of MVCHB system is simulated and analyzed.