Optimization of the pressure distribution in press-pack insulated gate bipolar transistors

The performance of press-pack insulated gate bipolar transistors (IGBTs) is greatly affected by the unbalanced pressure distribution. However, it is not feasible to apply engineering optimization methods to address the IGBT design problems because of the complexity of high-dimensional optimization involving the time-consuming simulation models. This paper proposes a practical structural design optimization (SDO) method, aiming to enhance the uniformity of the pressure distribution for the existing products of press-pack IGBTs. A concept of pressure balance factor (PBF) is first defined based on the stress distribution analysis of the IGBT, which establishes a direct link between the stress and structure of each sub-module. A PBF distribution function is formulated to reduce the dimension of the design problem. A parameterized SDO model is presented, which can be solved by classic algorithms by automatically calling the finite element model (FEM). This method is applied to a design problem of the actual press-pack IGBT with 44 sub-modules. Numerical results and an experiment show that it is with great practical potential because of the advantages of efficiency and operability.