Power Cell Design and Assessment Methodology Based on a High-Current 10-kV SiC MOSFET Half-Bridge Module

Abstract

While 10-kV silicon-carbide (SiC) MOSFETs are gradually penetrating medium-voltage (MV) applications, intertwined challenges concerning high-voltage insulation, high dv/dt, protections, and thermal management are simultaneously imposed to MV converters. For the modular multilevel converter, a systematical power cell design and assessment methodology (DAM) to tackle the unprecedented challenge synergy is essential and, yet, absent. Thereby, this article aims to develop a DAM based on a high-current 10-kV SiC MOSFET half-bridge module. An overall introduction of the power cell and a hierarchical DAM workflow is first presented, followed by the comprehensive component-level DAM with details on design challenges, solutions, assessment instruments, procedures, and test results. Subsequently, the DAM is expanded to the power cell level by exploring its safe operating area associated with switching frequency, power-processing capability, and temperature limit in various operation modes, which, in turn, validates the component designs and determines if they need iterations. Following the methodology, the power cell design is finalized, capable of continuous operation under 6 kV, 84-A rms, and 10 kHz, exhibiting 99.3% efficiency and transient immunity up to 100 V/ns.