Analysis and Design Optimization of Tilted Rounded-Rectangular Pin-Fins Heat Sink for xEV Double-Sided Cooling Power Module

This study proposes a novel design for a pin-fin heat sink and optimizes it to enhance the thermal performance of double-sided cooling (DSC) power modules applied in inverters for xEV applications. The circular pin-fins are conventionally adopted in automotive power modules. In this study, to decrease the junction temperature with the maximum ( T_j,max ) of IGBT bare-die, the pin-fin shapes are modified from conventional circular to a rounded rectangle. For further T_j,max reduction, the angle of the rounded-rectangular pin-fin is tilted. These shape modifications reduce the IGBT’s T_j,max thanks to three main reasons: (1) increased coolant velocity by reducing pin-fin spacing, (2) reduced wake behind the new pin-fin shapes, and (3) increased turbulence in the coolant by tilting the pin-fin angle. Finite volume method (FVM) simulations demonstrate that the best performance is achieved when the rounded-rectangular pin-fin is tilted by +15°. This enhanced new pin-fin design was fabricated and measured to demonstrate that the maximum device junction temperature was reduced by approximately 15.5 °C compared to a conventional counterpart. Moreover, the module thermal resistance was also decreased from 0.298 °C/W to 0.228 °C/W (by ~23 %) with an acceptable pressure drop. These results demonstrate that the proposed new pin-fin design is an effective heat-sink solution for indirect double-sided cooled modules and, once enhanced, can be comparable with direct cooled modules.