Improved Methodology for Conducted EMI Assessment of Wide Band-Gap Power Electronics

Abstract

Electromagnetic interference (EMI) compliance is a requirement for most electronic systems and devices, including power electronics. The emergence of power electronic systems designed with wide band-gap (WBG) semiconductors poses new challenges for compliance. This is due to the high edge rates achievable with WBG devices, coupled with unintentional grounding paths, some of which are introduced galvanically with traditional EMI compliance instrumentation. This makes it beneficial to use isolated measurement methods in place of traditional ground-referenced EMI instruments. This approach is viable in comparison to traditional EMI compliance measurements and can significantly reduce circulating ground currents, which can greatly impact emissions measurement accuracy. This paper proposes a streamlined method for emissions evaluation of power electronics employing an oscilloscope, differential voltage probes, and post-processing software implemented in MATLAB. This proposed method eliminates unintended metrology ground coupling, yields faster full quasi-peak scan times, and minimizes risk of instrumentation damage.

Keywords

• Quasi-peak
• QP
• common-mode current
• electromagnetic interference
• EMI
• ground current