Damp Heat Behavior of High Heat Capacitors for Applications in Electric Vehicles

Abstract:
Aging behavior of new generation capacitors intended for use at high temperatures in AC-DC inverter applications have been evaluated under damp heat conditions (85deg C and 85% relative humidity (RH)) and applied voltage over 1000 hours of aging. Two capacitor designs were tested, using 3micrometer and 5micrometer ELCRES(TM) HTV150A high-heat films, respectively. Test voltages were 0, 300 and 500 volts for the capacitors made with 3micrometer film and 0, 500 and 800 volts for the capacitors made with 5micrometer film. Capacitance change (DeltaC), dissipation losses (tan δ) and insulation resistance (IR) were tracked as indicators of aging performance. For both designs, DeltaC, tan δ and IR showed stable response with little or no change over the 1000-hour test duration. Tan δ and IR were independent of the applied voltage level. The change in capacitance (DeltaC) showed a slight increase (gain) of 1~2% with applied voltage. Meeting industry requirements for damp heat performance on the component level increases the confidence in employing the high heat capacitors in incumbent and new AC-DC inverter designs for electric vehicles.