With the rapid development of power electronics

high-frequency transformers are increasingly used in distributed power systems

electric vehicles

energy storage devices

and data centers. The trend toward high-frequency operation has significantly increased internal thermal load density

making heat dissipation to be a critical bottleneck in further advancement. To address this issue

we propose an optimized forced liquid cooling structure design method based on thermo-fluid coupling for epoxy-encapsulated high-frequency transformers. First

a multiphysics thermo-fluid coupling model is established

considering the temperature-dependent thermal properties of key materials

to analyze the temperature distribution and coupled heat transfer characteristics of windings and cores under high-frequency excitation. Then

using the response surface methodology (RSM)

central composite design

and finite element simulations

we construct a response surface model to correlate the maximum temperature with critical cooling structure parameters

including outer diameter

wall thickness

number of turns

and spacing. Finally

a multi-objective optimization is carried out using the NSGA-II algorithm with the aim of minimizing both the maximum temperature and coolant material usage

yielding a set of Pareto-optimal solutions. Representative schemes are selected using the entropy-weighted TOPSIS method based on different design preferences. A 200kVA/10 kHz high-frequency transformer is taken as an example

and the maximum temperature under natural convection cooling is 105.61 ℃

which is reduced to 64.44 ℃ with the optimized forced liquid cooling design

validating the effectiveness of the proposed method.