Large High Energy Density Pulse Discharge Capacitor Characterization

The energy density of film capacitors continues to increase. This paper discusses the performance issues of limited life pulsed discharge capacitors operating at better than 2 J/cc (2 MJ/m3) in the 5 kV to 20 kV range. Self-healing metallized electrodes have been utilized in these designs to provide graceful aging at electric fields greater than 500 MV/m. A variety of polymer films have been evaluated for use in these capacitors. The pulse rise times where the capacitors find application are in the range of microseconds to milliseconds. Life tests have been performed with the goal of achieving at least 1000 charge/discharge cycles at maximum energy density. Failure modes in normal charge/discharge pulse service, and short- circuit fault conditions have been evaluated. Design modifications to increase life and energy density were made based on those analyses. Capacitors delivering greater than 100 kJ above 2 J/cc have been built, tested, and shipped.