Design and Performance Evaluation of Overcurrent Protection Schemes for Silicon Carbide (SiC) Power MOSFETs

TLDR

Overcurrent protection of silicon carbide MOSFETs remains challenging due to limited practical knowledge. This study proposes three overcurrent protection methods to enhance reliability and reduce cost in SiC MOSFET converters. The methods include a solid‑state circuit breaker with a Si IGBT and gate driver, a desaturation technique using a sensing diode, and a novel active scheme that dynamically evaluates fault current, all evaluated in a phase‑leg step‑down converter under varied fault types and component settings. A comparative analysis of fault‑response time, temperature‑dependent behavior, and application suitability guides designers in selecting the most appropriate protection strategy.

Abstract

Overcurrent protection of silicon carbide (SiC) metal–oxide–semiconductor field-effect transistors (MOSFETs) remains a challenge due to lack of practical knowledge. This paper presents three overcurrent protection methods to improve the reliability and overall cost of SiC MOSFET-based converters. First, a solid-state circuit breaker (SSCB) composed primarily by a Si IGBT and a commercial gate driver IC is connected in series with the dc bus to detect and clear overcurrent faults. Second, the desaturation technique using a sensing diode to detect the drain-source voltage under overcurrent faults is implemented as well. Third, a novel active overcurrent protection scheme through dynamic evaluation of fault current level is proposed. The design considerations and potential issues of the protection methods are described and analyzed in detail. A phase-leg configuration-based step-down converter is built to evaluate the performance of the protection schemes under various conditions, considering variation of fault type, decoupling capacitance, protection circuit parameters, etc. Finally, a comparison is made in terms of fault response time, temperature-dependent characteristics, and applications to help designers select a proper protection method.