Thermal Management of Nonuniform Heat Fluxes in an Electric-Vehicle Fast-Charger: Experimental and Numerical Analysis

This article presents a novel approach to address nonuniform heat dissipation in high-power electrical systems, focusing specifically on an electric-vehicle (EV) fast-charger system. These systems often incorporate diverse power semiconductor devices with distinct electrical loads and thermal characteristics, leading to nonuniform heat fluxes. Due to manufacturing constraints, commercial off-the-shelf (COTS) heat sinks are unable to effectively handle these heat load distributions. To address this issue, this work utilizes a wire-arc thermal spray additive manufacturing technique to fabricate a topologically optimized heat sink for the thermal management of an EV fast-charger system. The optimized heat sink exhibits substantial volume reduction (81%) and mass reduction (71%) compared to a modified COTS heat sink. Experimental results demonstrate an average 27% reduction (0.02 °C/W) in overall thermal resistance and a 25% reduction (2.8 °C) in maximum heat sink surface temperature difference. Real-world implementation of the fast-charger system revealed a 78% reduction (7.6 °C) in interdevice temperature difference and a notable 14% reduction (13.1 °C) in maximum heat sink temperature within the most effective region. Numerical analysis substantiates these findings by emphasizing the significance of adapting the local Nusselt number based on the locally applied heat load. This work showcases the practicality of the proposed approach in designing and fabricating application-specific heat sink solutions for challenging thermal profiles prevalent in high-power fast-charger systems.