Weight-Minimizing Optimization of Microchannel Cold Plate for SiC-based Power Inverters in More-Electric Aircraft

Silicon-Carbide (SiC) devices are now a strong candidate for high-power inverter systems. However, in high-altitude applications like More-Electric Aircraft (MEA), the decreasing air density and the fact that inverters are housed in sealed enclosures with hardly air convection, add tremendously to the cooling challenge for SiC power devices which makes it inevitable to adopt liquid cooling solutions. In this paper, a weight-minimizing Pareto optimization is proposed based on the derived mathematical model for microchannel cold plate (MCP) to achieve minimum weight in multi-constraint system, including limitations of thermal performance, pressure drop, mechanical strength, cost, and weight. Moreover, two versions of MCP with different flow path configurations, V1 Series and V2 Parallel, are designed for trade-off comparisons. Both computational fluid dynamics (CFD) simulations and experimental results verify the accuracy of the derived mathematical model. Based on the comparison under same inlet flow rate, V2 Parallel has a pressure drop three to four times lower than V1 Series, while thermal resistance is only 22 % higher due to paralleled flow path. The eminent pressure drop performance of the V2 Parallel can help reducing pumping power which may further reduce external weight at system level. Eventually, the customized Aluminum-based V2 Parallel is adopted, with the thermal resistance around 0.0083 °C/W and pressure drop lower than 0.4 bar at the mass flow rate of 0.25 kg/s, while having only 810 g for the footprint area of 360 cm2, which is at least 40 % lighter weight than most off-the-shelf cold plates.