Thermal Analysis of Indirect Liquid Cooling for the Navy integrated Power Electronics Building Block

Abstract

The development of the Navy integrated Power and Energy Corridor (NiPEC) involves the deployment of modular, self-contained universal converter units known as the integrated Power Electronics Building Blocks (iPEBB). An iPEBB unit sees primary heat generation through four rows of MOSFET switches and a transformer, which produce 9600W and 1100W of waste heat respectively. In response to the Navy's prohibition of direct liquid cooling, indirect liquid cooling, which sees the iPEBB unit in dry contact with a liquid-cooled cold plate, has been chosen as a potential thermal solution. A half-iPEBB thermal model was created and tested in steady state using computational fluid and thermal simulation. The chosen cold plate design using a flow rate of 8.4 gpm and inlet temperature of 25°C was found to reduce MOSFET temperatures to a maximum of 148°C, providing 2°C of margin to operational limits. Heat pipes were explored to counter the high temperatures (>100°C) seen within the ferrite transformer core, resulting in highs between 82°C and 118°C for the range of possible ferrite thermal conductivities. This preliminary analysis confirms the viability of indirect liquid cooling for the MOSFET switches of the iPEBB unit and provides insight into the design of the cooling solution for the transformer core. These findings will inform the requirements of the system-level cooling solution and offer a reference for future experimental testing of the iPEBB unit.