Energy Buffer Capacitors for Use in Dynamic Power Conversion ACUs

Dynamic power generation systems such as Stirling engines are a key element of spacecraft designed for deep space missions, lunar exploration and other applications where photovoltaic arrays have limited, or no exposure to the sun.nbsp; Electronic components used to process the electrical power have to operate in close proximity to the Stirling radioisotope generator as well as extreme temperatures.nbsp;nbsp; This development addresses two of the largest components in a advance power control unit (ACU).nbsp;nbsp; An energy buffer capacitor which minimizes ripple current, voltage fluctuations and transient suppression, and an AC power factor correction capacitor that performs a tuning function.nbsp; There is a well-defined need, to develop capacitors for this application, to improve the system reliability over at least 20 years of life, and to reduce volume and weight which are critical parameters for any space mission.nbsp; The Phase I project demonstrated the use of a disruptive NanolamTM capacitor technology to produce prototypes of 750mF/50VDC energy buffer capacitors and 71mF/240VAV capacitors.nbsp; When compared to state of the art metallized film, electrolytics and multilayer ceramic capacitors, the NanolamTM capacitors havenbsp; up to 10X energy density and 10X specific energy, with excellent capacitance stability with temperature and bias.nbsp; The primary objective of the proposed Phase II program is to complete the development of both DC and AC NanolamTM capacitors, specifically designed for NASA dynamic energy conversion ACUs, and to supply parts to NASA technical personnel for evaluation.nbsp; Specific tasks include the development of larger 4.4mF/50V capacitors, bus bar design to handle high ripple currents, packaging and producing AC NanolamTM capacitors with a two layer electrode system, to maximize life in environments that can induce electrode corrosion.