Multiphysics Digital Model of the High Frequency Transformer for Power Electronics Application Considering Electro-Thermal Interactions

The high frequency transformer (HFT) applied in the power electronics operate under the combined stresses of high-frequency pulsewidth modulation (PWM) voltage and high temperature. The electro-thermal coupling effect can accelerate the aging process and even cause the failure of the HFT's insulation. The accurate modeling and simulation of the multiphysics fields of the HFT is crucial for investigating the electrical and thermal stresses on the insulation. The interaction between the electromagnetic and temperature fields in HFTs makes this task challenging. Specifically, the temperature field in HFTs is influenced by electromagnetic losses, while the electromagnetic parameters of the material and loss distribution are related to temperature and voltage frequency. This article explores the interaction between high-frequency electromagnetic and temperature fields and develops a comprehensive multiphysics coupling model based on the analyzed results. The model allows for the digital replicate of the circuit, electric, magnetic, and temperature fields and it provides precise identification of the electrical and thermal stresses on the insulation. A 60 kHz HFT for dual active bridge applications is taken as the example and the simulation results indicate that the proposed model can improve accuracy by 19.14% compared to conventional methods. Finally, a high-frequency PWM test platform for the HFT is developed, and the proposed model is validated through experimental results.