Two-Stage Electric Field Optimization Method for High-Voltage Power Module Using Dielectrically Graded Insulation Micro-Region

Dielectrically graded insulation (DGI) with spatially inhomogeneous dielectric parameter distribution can provide extraordinary insulation performance for high-voltage power equipment. The most crucial objective in the application of DGI is to identify the optimal distribution of dielectric parameters. However, the calculation efficiency and electric field optimization results of the existing methods are poor under complex insulation structures. Also, the dielectric loss of DGI calculated by these methods is relatively large. In this work, an efficient DGI parameter optimization method was developed. First, a variable density topology optimization model was proposed to improve the electric field uniformity of the power module and suppress the electric field stress at the triple point. Second, the influence of different model parameters on the mitigation degree of the electric field was studied to obtain the optimal parameters. Finally, to reduce the dielectric loss of the insulation, the DGI micro-region was constructed by narrowing the optimized region. Numerical results indicate that the model only needs 23 iterations to obtain the optimal result. After optimization, the electric field stress at the triple point is reduced by 71.7%. DGI micro-regions reduce dielectric loss by 85.1% compared to global DGI. This study shows that the proposed method is anticipated to provide a new route for the preparation and application of DGI.