Stacked annular form factor film capacitors for high voltage and high current applications

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. The 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 stack is greatly simplified. Furthermore, the annular form factor allows for optimal interconnections between capacitors, thus providing a high voltage capacitor stack with an ESL comparable to conventional configurations. The 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.