Design optimisation of air-forced heat sink to improve temperature gradient in power semiconductor modules

This paper presents a numerical optimisation of an air-forced heat sink design for application in cooling systems for power electronic devices. A three-phase inverter is a typical power electronic circuit which commonly employs three or six power semiconductor modules installed in a row on an air-forced heat sink. When power loss is evenly distributed among the modules, the temperature increases along the heat sink in the direction from the air inlet to the outlet, creating a thermal gradient across the power semiconductors. This thermal gradient is a negative factor, leading to mechanical stress in the semiconductor structure and reducing the device’s reliability and lifespan. To improve the temperature gradient, the study proposes a modification to the standard heat sink design by introducing a V-shaped cut in the fin area near the inlet. This modification creates an inconstant distribution of thermal resistance along the length of the heat sink reducing temperature variation. Numerical simulations were conducted to identify the optimal V-shaped cut configuration providing minimal temperature differences between modules. The optimal value of the V-shaped cut was determined to be 0.255pu, while the standard deviation of the temperature difference between the power semiconductor modules was reduced from 2.194 to 0.183 at a heat flux of 100W per module. The results show that the optimised design significantly reduces the thermal gradient, ensuring a more uniform temperature distribution across the semiconductor modules.