A Review of Partial Discharge in Medium Voltage SiC Power Modules Under Square Wave Excitation: Characterization, Mitigation, and Detection

The medium voltage (MV) silicon carbide (SiC) power modules hold significant promise as a route for the solid-state converters to achieve higher power density, higher switching frequency, and lower loss. However, the emergence of partial discharge (PD) in the MV SiC power modules has posed a formidable challenge to enhancing its nominal voltage. In this paper, a comprehensive review and comparative analysis of characterization, mitigation, and detection of PD under the square wave excitation is proposed for MV SiC power modules. First, the mechanism, detriments, and characterization of the PD issue and electrical tree in the MV power module are insightfully demonstrated. Meanwhile, the challenges from the PD for the MV SiC power module are emphasized. Besides, the geometric modification of direct bonded copper (DBC) structures to mitigate the PD issue are reviewed in detail. The limitations of the customized DBC are analyzed, considering the cost, reliability, and thermal resistance. Additionally, advanced dielectric materials are introduced and categorized. It is indicated that the effectiveness of the new dielectric under the square wave excitation stress still needs further investigation. Meanwhile, the optical, electromagnetic, electrical, and ultrasound detection methods under square wave excitation are further reviewed to assess the PD behavior in the MV SiC power module. Lastly, suggested future researches for MV SiC power module packaging are proposed, aiming to inspire new ideas to further promote the insulation level of the MV SiC power module.