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In this paper, 3-D simulation of heat transfer in a power electronic device and its cooling system is performed. The device is a high voltage three-phase inverter manufactured by Semikron Company which its main application is in electric and hybrid vehicles. Cooling system is a forced-air plate-fin heat sink. Limitation factor of designing heat transfer is maximum temperature of the inverter’s chips, heat sources, called IGBT. Maximum temperature of IGBTs should be below 125 ᵒC in order to avoidance of both the thermal and the mechanical failures. One of the primary objectives is the reduction of the maximum temperature by designing layout of chips. Also, the heatsink geometry design is accomplished with the consideration of the maximum temperature and tradeoff between both the usage material volume and the heatsink efficiency. Geometries are the number of fins, the fin height, the fin thickness and the base thickness of the heatsink. The power dissipation is estimated using datasheet information and output waveforms obtained from simulation in MATLAB. A thermal model of the inverter and its cooling system are simulated by using finite-element method (FEM). The accuracy of the thermal model and power dissipation estimation are verified by Semisel software. The maximum temperature is significantly reduced about 20 ᵒC by designing layout precisely. Also, the heatsink efficiency is increased 10.35%, 16.67% and 27.51% with the increase of the material volume about 22.52%, 13.51% and 0% for the heat transfer coefficient, 50, 75 and 100 (W/m2.K) by good design of the heatsink geometry ,respectively.

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One of the main problems in the commercial use of lithium-ion batteries for high energy consumption is the heat problems associated with these batteries. Since many batteries are used together in order to generate higher power, it is important to predict their thermal performance. In this study, a heat management system of a lithium-ion battery equipped with a heat pipe is investigated. For this purpose, a part of a battery pack consisting of two batteries and a heat pipe is selected and its performance is experimentally investigated. These tests are performed at various ambient temperatures through a made test chamber with the ability to accurately control temperature. The experimental results show that although with increasing ambient temperature, the battery surface temperature increases, but due to the decrease in thermal resistance of the heat pipe, the effect of this temperature rise can be moderated and work as an active method. In addition, using forced convection in the condenser section, not only can the battery surface temperature be controlled below 40 ˚C, but it also distributes the temperature uniformly over the battery surface. The use of the heat pipe also helps to maintain more stable temperature conditions with lower temperature fluctuations in consecutive battery cycles.