Advanced Cooling Methods for Film Capacitors

Power inverters convert electrical power from one voltage and frequency to another. They are used in a variety of commercial and military systems, including electric vehicles, solar and wind energy power conditioning, and More Electric Aircraft. The ability to effectively cool the capacitors in these inverters is limiting the maximum operating temperature and packaging density of the inverters. Current practice is to reject heat axially, from the base of the capacitor to a mounting plate. This results in large temperature gradients and limits capacitor performance. This Phase I program will investigate cooling the capacitors radially, using a high-conductivity thermal link to bring the heat to the base plate. Finite Element analysis has shown that this approach allows higher capacitor power dissipation before reaching a limiting dielectric temperature and eliminates local hot spots that can lead to early failure. Effective capacitor cooling will allow reduction in the number of capacitors used and use of coolants operating at higher temperatures. It will also allow the use of COTS components, such as commercially-available, unmodified capacitors, with their proven high reliability and known characteristics. Phase II will construct and demonstrate one or more inverters using this radial cooling technology in relevant environments.