Direct Contact Jet Impingement Cooling with Non-conductive Fluid for Power Converters that Enables Increased Power Density

This digest presents a jet impingement cooling scheme that is adapted to an existing air-cooled power converter. This jet impingement cooling is novel as it leverages automatic transmission fluid (ATF), a non-electrically conductive fluid, as the liquid medium. This allows for direct contact of the liquid medium with conductive components, including the exposed heat dissipating pad of a FET which is commonly connected to its drain and held at high potential. This is in contrast with typical jet-impingement cooling schemes which use ethylene-glycol to cool a heatsink that is then interfaced with the heat dissipating components. The proposed scheme negates the need for this heatsink and the electrically insulating and thermally conductive interface between it and the FETs. The resulting cooling technique allows for a more efficient heat transfer into the liquid medium. Results are validated with simulation. Through comparison with an existing high-performance forced-air cooler it is demonstrated that this cooling method will allow for both an increase in output power and a decrease in volume, resulting in a >50% increase in power density. Lastly, the efficacy of this scheme in a motor drive environment is presented, where it is shown that this cooling method alongside an LC filter placed between the inverter and the motor will result in both increased efficiency and power density.