Multi-objective and Finite Element Based Optimization of High-Frequency Solid State Transformer For Electric Vehicle Applications

This article presents an optimization strategy for High-Frequency Transformers (HFT) in Solid-State Transformer (SST) applications in Electric Vehicle (EV), based on the Finite Element Method Magnetics (FEMM) and multiobjective design. SST is a lighter and more compact transformer than conventional steel core transformers, making it an important component of current EVs. Various technical aspects of SST concepts have been proposed and analyzed in literature. In contrast to existing works which propose mathematical and physics-based simulation of the core geometry and magnetic flux distribution, this paper adopts an FEMM strategy to generate different iterations of the geometries and flux distributions for the HFT design optimization for SST application. A multi-objective non-dominated sorting optimization technique is used to design the 85 kHz, 10 kW HFT, which reduces the core volume (maximizing power density), total transformer losses, and overall cost based on a collection of multiple Pareto-Optimal Solutions (POS). The results from each simulation are carefully analyzed, each core material demonstrates different properties in terms of power loss, power density and cost, the best core material can be selected depending on the objective of priority. The average efficiency of the pareto-optimal solutions was greater than 97.5%, which is excellent for SST designs. The hardware implementation of the final optimized HFT design is currently underway and will be presented in a future publication.