High temperature capacitors with high energy density

Power electronics are a key technology for hybrid and plug-in electric drive vehicles (EDV) and represent 20% of the material costs. DC bus capacitors are one of the critical components in EDV power inverters and they can occupy ∼35% of the inverter volume, contribute to ∼23% of the weight, and add ∼25% of the cost. Current polypropylene (PP) film capacitors have dielectric constant K of 2.2 and temperature stability lower than 105 °C. We recently developed a modified Polyvinylidene fluoride (PVDF) which combines high dielectric constant, low dielectric loss, low leakage current, high dielectric breakdown strength, and high temperature stability. The modified PVDF capacitor film also has graceful failure feature which is critical to applications demanding high reliability and long lifetime. The thermoplastic nature of the modified PVDF ensures that they can be processed into thin capacitor film using inexpensive melt extrusion and biaxial orientation process. In this report, DSC and dielectric spectroscope test results of the novel capacitor film will be presented.