Investigation about the electro-thermal behaviour of high power/high frequency planar transformers

Planar transformers are a good choice when designing high frequency switching mode power supply (SMPS). Since these devices have some advantages over wound transformers that improve the SMPS performances, their use is growing in the last years. One of them is that, due to the planar geometry and proximity of the windings, parasitic effects at high frequency can be reduced. This paper presents a study of two different winding arrangements to compute the electromagnetic loss and the temperature distribution inside the planar transformer. The study is carried out using the Finite Element Analysis and taking into account the frequency effects for the electromagnetic model. A Finite Element Algorithm is also applied to solve the thermal model for the computation of the temperature distribution. An experimental prototype is built and measurements are performed validating the numerical results.