Comparison of Electric Field Calculation Methods for Optimization Routines to Design Medium-Frequency Transformer Insulation

Since the insulation volume of medium-frequency transformers (MFTs) typically constitutes a significant fraction of the overall transformer volume, design routines focusing on optimizing insulation are crucial. Such optimization requires fast and accurate electric field computations in several critical regions of the MFT, making the choice of effective computation methods essential. This paper compares suitable methods, including the Schwarz-Christoffel transformation (SCT), the charge simulation method (CSM), and commonly used analytical approaches, by benchmarking them against nearly 4000 finite element analysis (FEA) simulations. Each method's error is analyzed, and a sensitivity study is performed to define the parameter ranges where each method yields accurate results. The CSM is found to provide the most accurate field computation ($< $5% error) across all examined critical regions. However, to compensate for its increased computation time for geometries with rectangular conductors, combining the CSM with the SCT – which is approximately 10 times faster – is recommended to achieve optimal performance.