Mitigating Conducted EMI with SiC Solutions in Renewable Energy & Grid-Connected Power Converters

Abstract:
Power converters based on wide-bandgap semiconductor technology such as silicon carbide (SiC) MOSFETs unlock higher power density and higher efficiency compared to power converters based on silicon (Si) IGBTs by virtue of SiC’s faster switching speed. However, faster switching speed can lead to higher electromagnetic interference (EMI), which is a crucial problem for circuit designers. In this study, electromagnetic compatibility (EMC) is investigated for a 25kW, three-phase/level T-type neutralpoint- clamped, grid-connected bidirectional inverter switching at 60kHz. This inverter is designed for high-power applications like solar inverters, uninterruptible power supplies (UPS) and energy storage systems (ESS). The test setup is based on the IEC-61000-6-3 standard and measures the emissions conducted to the grid by the inverter. Thereafter, a passive EMI filter is designed and implemented to mitigate the inverter’s conducted emissions, and measurements are taken to validate the performance of the filter. It is observed that the measurements are within the limits of the IEC-61000-6-3 standard.