Design of longitudinal multisection foil-film capacitors

This paper analyzes the design of foil film capacitors with series sections in the winding direction, a winding design which facilitates very high voltage windings although of limited energy density as a result of the foil electrodes which do not self-clear. An equivalent circuit is provided on the basis of which the electric performance is investigated. Normally, such windings suffer from very high ESL resulting in low self-resonant frequency; however, an approach to winding design is suggested which reduces the ESL substantially. Although the metal foil electrodes do not clear, this design wastes little volume as the result of the margins between sections and therefore maintains good volumetric efficiency, unlike metalized film windings with series sections which the authors have analyzed previously.