Thermal Considerations of a Power Converter With Components Embedded in Printed Circuit Boards

Printed circuit board (PCB) technology is attractive for power electronic systems as it offers a low manufacturing cost for mass production. Integration technologies such as device embedding have been developed to take advantage of the interlayer space in multi-layer PCBs and to increase the performances (electrical and thermal). However, the PCB technology offers limited power dissipation due to the low thermal conductivity [≈0.3 W/(m · K)] of its composite substrate. In this article, we consider PCB embedding for a 3.3-kW ac/dc bidirectional converter. We describe the integration of not only the power dies but also the gate drive circuits and the power inductor, with a special focus on thermal management. The manufacturing processes of the boards are presented. Two thermal models based on finite elements (FEs) of this converter stage are introduced. The accuracy of these models is validated against experiments. The results show that a simplified FE model offers satisfying accuracy and fast simulation, even considering the relatively complex structure and layout of the PCBs.