Nanocomposite Film Dielectrics for High Temperature Power Conditioning Capacitors

Emerging power electronics in a broad range of military, aerospace, hybrid vehicle, renewable energy and drilling applications rely on advances in dielectric materials for capacitors. Compact capacitors possessing low dielectric loss and high operating temperature capability are needed for power conditioning in advanced converter and inverter designs for these applications. Wound film capacitors represent the preferred capacitor technology but are limited by low operating temperature capabilities, < 150°C, and low volumetric efficiency, capacitance per unit volume less than 1.0 μF/cc. TPL is developing processes and manufacturing techniques for fabrication of advanced capacitor films comprised of high temperature polymers modified with ceramic nanoparticles. The selected polymers enable high temperature operation and the ceramic nanoparticles enhance volumetric efficiency by increasing the dielectric constant. The fabricated films are adaptable to conventional wound film capacitor construction methodologies. This paper provides an overview of TPL's experience to-date with a film dielectric material system comprised of fluorenone polyester polymer and titanate nanoparticle filler. The fluorenone polyester polymer was selected to provide a stable operating temperature of at least 200°C, while the addition of the titanate powder increases the dielectric constant and, in turn, the volumetric efficiency of wound film capacitors constructed with this film system. Status and ongoing capacitor development issues are provided relative to the intended high temperature power conditioning applications.