Study on thermal design due to downsizing of power module using coupled electrical-thermal-mechanical analysis

Recently, with the development of power electronics technology, the power modules have been used extensively and the demand for downsizing. At our laboratory, the power assist to support knee moving has been developing. And this product also uses power module to improve energy efficiency. The problem of the power module is thermal fatigue of the junction area between SiC chip and substrate. When downsize the power module, thermal design become more important because it gets more difficult to release heat produced in the module. In this study, assuming practical use of power assist, proposing a model of power module under power cycle test that allows further downsizing and reducing weight was conducted. And thermal design of power module was evaluated by using coupled electrical-thermal-mechanical analysis. The analysis using Finite Element Method (FEM) was operated to evaluate non-uniform temperature distribution in power module was estimated. Based on the results, the model of power module is proposed as effective solution for downsizing without reducing the reliability.