Directly Cooled Silicon Carbide Power Module: Pin-Fins Roughness Effect on Pressure Drop

The use of silicon carbide (SiC) in power semiconductor modules has led to higher power density, increased maximum junction temperature, high voltage application, and more compact devices, which require efficient cooling systems. This study was to investigate the influence of the surface roughness on the pressure drop of ACEPACKTM DRIVE, a commercial SiC-based power module for traction inverter. This power module has a cylindrical pin-finned baseplate that is mounted on a dedicated cooling device (water jacket) in which coolant media flows. The analysis aimed to characterize the pressure drop between the inlet and exhaust sections of the water jacket, with the objective of optimising the coolant flow for an efficient module cooling, avoiding both excessive resistance and insufficient flow. Confocal laser scanning microscope was used to measure roughness on two different pin-fins with the same geometric characteristics but different surface roughness. Pressure drop measurements were taken at different coolant temperatures and flow rates using a hydraulic test bench. Results indicate that the pressure drop of the higher roughness configuration is 13-19% smaller than the first one, depending on the flow rate and coolant temperature. The suggested reason is that this decrease is caused by a reduction in pressure drops due to concentrated losses associated with fluid flow separation.