Implications of advanced capacitor dielectrics for performance of metallized film capacitor windings

A range of high dielectric capacitor films is under development with the objective of improving the energy density of pulsed discharge capacitors. A substantial change in capacitor film dielectric constant has implications for capacitor design and function. This paper develops formulas for equivalent series resistance (ESR) and equivalent series inductance (ESL) of a cylindrical capacitor winding as a function of material properties and winding design. A numerical approach is used to investigate the frequency-dependent ESR and ESL, after which formulas are developed for winding inductance based on a resistive current distribution in the winding. Analyses are carried out for a cylindrical metallized film winding in which the return conductor is brought either through the center of the core on which the film is wound or coaxially up the outside of the winding, so that both connections are made from the same end of the capacitor with minimal inductance. The implications of moving to high dielectric constant film are investigated on the basis of this analysis.