Abstract
Increasing the current density of electric machine windings is a means to increase the torque density, and thus the power density, of an electric machine. The peak achievable current density is governed by the ability to remove heat from the windings subject to material temperature constraints. Traditional thermal management schemes use external cooling jackets or other approach where the coolant indirectly interfaces with the windings. However, recent studies have shown the use of printed circuit boards (PCB) as a shared substrate for both cooling channels as well as copper traces, with demonstrations of planar inductor coil current densities that exceed those in traditional power-dense machinery. In view of this application need, this study explores an approach to increase the achievable current densities to > 100 A/mm2 in windings using direct liquid cooling of copper traces on PCBs. This is enabled by fabricating multi-layer board stacks having embedded microchannels for cooling with a dielectric fluid that is in direct contact with internal copper winding traces.
