PEN/Si3N4 bilayer film for dc bus capacitors in power converters in hybrid electric vehicles

High performance hybrid bilayer capacitor film has been developed by controlled deposition of silicon nitride (Si3N4) on polyethylene naphthalate (PEN). It was found that silicon nitride prepared with plasma-enhanced chemical vapor deposition can significantly increase the dielectric constant (K) and energy density of PEN by more than 20% and 50%, respectively. Moreover, the PEN/Si3N4 bilayer hybrid film also exhibits appropriate mechanical and thermal properties for capacitor winding. The high operating temperature and energy density of the PEN/Si3N4 bilayer dielectric film are very attractive for dc bus capacitors used in power inverters or converters found in hybrid electric vehicles, wind turbine generators, grid-tied photovoltaics, and smart grid, as well as pulsed power systems.