With the fast development of high-temperature metal oxide semiconductor field effect transistors for power electronics in electric vehicles, current state-of-the-art biaxially oriented polypropylene (BOPP) film capacitors need further improvement because they have a temperature rating of only 85 °C without derating the voltage to maintain a long lifetime. If a high-temperature polymer can replace BOPP without sacrificing the overall dielectric performance and cost, it is possible to remove the current water-cooling system for capacitors and significantly reduce the cost of the power electronic unit. In this work, we demonstrated new polycarbonate (PC)/nylon multilayer films (MLFs), which has a potential for even higher temperature rating because of the higher melting temperature for nylons (e.g., nylon-6). Structural and dielectric studies showed that these PC/nylon MLFs had a similar dielectric performance, such as dielectric constant, dielectric loss, and breakdown strength, as the PC/poly­(vinylidene fluoride) PVDF MLFs, which were developed in the past. These PC/nylon MLFs could perform well up to 120 °C, which was limited by the glass transition temperature of PC at 145 °C. More intriguingly, packaged PC/nylon-12 MLF capacitors exhibited a self-healing capability, which had been difficult for packaged high-temperature film capacitors. Because self-healing is such a fundamental requirement for polymer film capacitors, our PC/nylon MLFs offer a potential for next-generation high-temperature and high-energy density film capacitors.

Voltage overshoot is defined by stray series inductance and turn-off time, which must be managed to avoid failure of IGBT's in inverter applications.The total equivalent series inductance (ESL) is dictated by internal switch branch inductance with a significant contribution in the current path to the DC link capacitor. Using traditional topologies, external ESL dominates and by-pass capacitors ("snubbers") are used to mitigate overshoot. Integrated capacitor/bus designs provide an external ESL comparable to internal values for commercial IGBT's. The minimized ESL regime allows reduced switch turn-off time with slightly increased losses to manage overshoot without the cost, space, weight, dissipation, and reliability associated with by-pass capacitors.

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An annular form factor dry film capacitor having the minimum possible Equivalent Series Inductance (ESL) has been developed for short pulse applications requiring high currents at voltages below 10 kV DC. This part is based on a multi-section design, which provides very good voltage grading between the end faces of the capacitor. This grading is preserved when using the capacitor as a building block for a stacked series assembly to realize much higher operating voltages. As such, the dielectric design of the resulting assembly is greatly simplified. Furthermore, the annular form factor greatly simplifies interconnections between capacitors, thus providing a high voltage capacitor stack with an ESL comparable to conventional configurations. Electrical and mechanical aspects of series stacked annular capacitors are discussed, including interconnect conductive "gasket" materials and mechanical clamping arrangements. A stacked capacitor design is presented along with preliminary test data.

US Department of Energy, Oak Ridge National Laboratories (ORNL) and SBE, Inc. report test results comparing the Toyota Lexus, Camry, Prius (both new and end of life) and Kemet capacitors with the SBE PowerRing. While exact comparisons are difficult because of size, shape and terminal configurations the SBE capacitors showed from 4 to 8 times lower temperature rise than the others tested and with substantial volumetric reduction as well.