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

Abstract

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, 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 paper, 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 the thermal management. The manufacturing processes of the boards are presented. Two thermal models based on finite elements (FE) 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.

Design of a High-Power Multilevel Sinusoidal Signal and High-Frequency Excitation Module Based on FPGA for HIFU Systems

“…The resistive element is an I2R loss due to the current through the device, and it is "on" resistance. Heat is also generated each time the device is switched on, due to its current voltage (IV) characteristic [21][22][23]. This loss is proportional to the switching frequency.…”

“…A by-product of this construction is that FR-4 has very low thermal conductivity. Figure 3a shows a typical cross-sectional geometry for a two-layered FR-4 board [22,27]. Using the thermal conductivity values in Table 1, the thermal resistance for an FR-4 board can be calculated by adding the thermal resistances of the layers.…”

“…During MOSFET operation, energy loss is converted into heat, which occurs mainly in three parts: energy loss on MOSFET, power loss on-resistance, and conduction loss during MOSFET switching. To determine whether or not a MOSFET is suitable for a particular application, we must calculate its power dissipation, which consists mainly of diode power dissipation, resistive, and switching losses [21,22]:…”