Investigation of Electrical Stress in High Voltage IGBT Power Module Using Finite Element Simulations

With increase in the demand for electrical power conversion and control, new power electronic technologies are being developed rapidly. The power conversion is possible because of silicon power devices which are the most important components of any power electronic system. Among the power devices, insulated gate bipolar transistors (IGBT) are more accepted and widely used in various applications. The blocking voltage rating of the IGBT has increased up to 6.5kV which has resulted in higher demand on the partial discharge and insulation resistance of the insulating material. The use of IGBT module in high voltage applications can develop high electric field strength at the junction of silicone gel, substrate and the metallization. This high field may create an electric discharge known as partial discharge in the silicone gel if there is any flaw like protrusion at this location, which gradually results into the failure of electrical insulation, lowering the reliability of the IGBT module. In this paper, the high electric field is localized and its value is found using finite element analysis of IGBT module, with protrusion and without any flaw, according to IEC 61287 standard.