150 °Celsius Capacitors for DC-Link Applications

Abstract:
Newly introduced high-heat ultra-thin dielectric film has been used to build high temperature commercial quality capacitors suitable for DC-Link applications. The capacitors have been tested at high temperatures reaching 150deg C. Operating at 900 volts, the capacitors passed 2000 hours of life testing at 150deg C, and passed 3600 hours at 1000 volts and 130deg C. Insulation resistance (IR), dielectric losses (tan δ) and Equivalent Series Resistance (ESR) were stable over the test duration. A positive capacitance change (DeltaC) was noted early in the test and remained acceptable at the end of the test. Reaching 900V and 1000V performance was enabled by appropriate segmented metallization of the dielectric film and process optimization for building capacitor elements. Achieving 150deg C performance was possible due to stable inherent dielectric characteristics (BDS, Dk and Df) of the high heat film. Operating at high temperature and high voltage is advantageous for efficiency improvement in AC-DC inverter modules, in particular those based on SiC technology. Additionally, the demand for active cooling can be reduced or eliminated giving rise to compact module design and bringing the capacitors closer to the SiC switch for lower induction losses. Compact designs may offer opportunity for weight reduction in electric vehicles.