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. The modified PVDF capacitor film also has graceful failure feature which is critical to applications demanding high reliability and long lifetime. 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. Current polypropylene (PP) film capacitors have dielectric constant K of 2.2 and temperature stability lower than 105 ☌. 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. Power electronics are a key technology for hybrid and plug-in electric drive vehicles (EDV) and represent 20% of the material costs. In many cases, further development of promising polymers that appear to possess all or most of the important criteria is limited by lack of large scale market incentives, but could be of great value to niche applications in the military or aerospace realm. Some historical background and discussion on the limitation of the commercially-available polymer film dielectrics for high temperature applications are also given. The present review first explains the advantages of metallized polymer film capacitors over the film-foil, ceramic, and electrolytic counterparts, and then presents a comprehensive review on both past developmental effort of commercial resins and recent research progress on new polymers targeted for operating temperature above 150 ☌. Simultaneous demands of processability, dielectric permittivity, thermal conductivity, and dielectric breakdown strength dictated by increasing high power performance criteria limit the number of available materials. Much effort has been invested for nearly five decades to identify and develop new polymer capacitor dielectrics for higher than ambient temperature applications. Of interest is developing a better understanding of how the device architecture and its electrical properties affect its performance as a filtering device in a high power, high frequency application. Both predicted electrical properties and empirical data were utilized as SPICE simulation input parameters to evaluate the performance of the different capacitors in an interleaved DC-DC boost converter model. A finite element analysis of the device architectures was used to develop a better understanding of how magnetic fields and thermal profiles affect the performance of the capacitors in maintaining a low ripple voltage at high switch rates (>20 kHz).

A modeling and simulation capability was used to investigate device architecture and electrical performance relationships for a select group of wound and stacked devices, which were then evaluated for use in a power conditioning application. These efforts have highlighted the need to develop capacitor technology for high power, high frequency power filter applications, which can experience cycling over a wide range of temperature (-55 degrees C to 250 degrees C). Recent advances in SiC power devices and high temperature magnetic and insulation materials has led to an increase in activity to develop compact, high switch rate power system components that can operate at temperatures in excess of 200 degrees C.

Unpkg material 2 dev