Thermal Management of SiC Devices in High-Power EV Fast-Charging Converters: A Novel Proposal Based on Vapor Chambers

The rapid adoption of electric vehicles (EVs) has increased the demand for high-power EV fast-charging converters, intensifying thermal stress on discrete power semiconductors such as silicon carbide (SiC) MOSFETs and diodes. Efficient thermal management is therefore crucial for maintaining device reliability, particularly at high switching frequencies and high-power densities. This paper presents a comprehensive thermal optimization framework for integrating vapor chambers into high-power EV fast-charging converters. Using the Wolfspeed CRD-60DD12N-K 60 kW LLC resonant converter as a reference, the baseline thermal behavior is characterized through COMSOL Multiphysics simulations of a forced air-cooled heat sink. A multiphysics model is developed to incorporate a copper-water-vapor chamber, accounting for wick porosity, laminar vapor flow, and phase-change heat transfer. Thermal performance enhancements are demonstrated through experimental benchmarking, with vapor chamber integration reducing peak device temperatures by over 39 % and significantly improving temperature uniformity. An optimization algorithm is implemented in MATLAB to minimize the dimensions of the vapor chamber and heat sink while satisfying heat-transfer limitations imposed by capillary, boiling, viscous, sonic, and entrainment constraints. The validated simulation model demonstrates the potential to reduce the vapor chamber footprint by 41.8 % and the heat-sink area by 34 % without compromising thermal reliability. These findings establish the viability of compact, high-efficiency vapor-chamber-assisted thermal solutions for next-generation high-power EV fast-charging converters.