Thermal Modelling of Planar Transformers Considering Internal Power Loss Distribution

Planar transformers are widely used in high- frequency high power density power electronic converters. With the demands of miniaturization, more detailed analysis of thermal stress of the transformers is necessary to enhance its reliability. Due to the strong coupling between the power loss and the distribution of the temperature, a model-based design considering the thermal issue together with the winding configuration is essential. This paper presents a thermal modelling method for planar transformers considering different winding configurations and internal uneven power loss distribution. The temperature distributions of different locations in the transformer windings and cores are identified. The impact of the winding structure on the thermal behavior is analyzed. Finally, A case study with a simplified analytical model, computational fluid dynamic (CFD) simulations, and experimental results are presented for verification.