SBIR-STTR Award

This NASA Phase I SBIR proposal addresses the development of energy buffer capacitors to replace multilayer ceramic (MLC) capacitors used in the advance controller unit (ACU), of dynamic power conversion systems. Dynamic power conversion systems designed for long duration deep space missions, require stable and reliable ACUs to precisely control the function of the energy conversion system and provide DC power to the spacecraft. MLCs have poor capacitance stability with temperature, voltage and time on voltage. This development proposes to design, produce and evaluate energy buffer capacitors using Nanolam capacitors, developed for use in inverters of hybrid and electric vehicles. Nanolam capacitors comprise 10,000s of high temperature radiation cured polymers that have superior capacitance and dissipation factor stability in the temperature range of -196oC to +200oC. Nanolam capacitors are self-healing, prismatic in shape and they are radiation tolerant. One unique feature of the Nanolam capacitor technology is the use of submicron polymer dielectric layers. It has been demonstrated that as the thickness of the cross-linked amorphous dielectrics decreases below about 1.0mm, the breakdown strength increases significantly, which results in capacitors with superior energy density. Internal series sections allow Nanolam capacitors with dielectric thicknesses of few hundred nanometers to service applications with voltages as high as 10,000V. The proposed development will produce and evaluate energy buffer Nanolam capacitors with a rating of 1200mF/175VDC for an 120V power bus. A single Nanolam capacitor will be used to replace at least ten individual MLC parts, mounted on a PCB to make up the 1200mF. The major project objective is to demonstrate superior capacitance stability, energy density and specific energy to MLCs as well as deliver parts to the NASA technical personnel for independent evaluation. Potential NASA Applications (Limit 1500 characters, approximately 150 words) Radioisotope dynamic power conversion systems controllers, as well as roll-out photovoltaic array controllers used to power Hall thrusters, are tailored mostly to 120V and there is some ongoing development with 300V systems. Nanolam capacitors can replace multilayer ceramic capacitors in multiple circuits of a single controller. Potential circuit applications include power factor correction in a rectifier circuit, energy buffer in an AC/DC inverter and DC-link in a DC/DC inverter. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words) Developing lower voltage capacitors will greatly expand the Nanolam market size and application space. Non-NASA applications include inverters for residential and commercial PV systems, battery chargers, inverters for 48V automotive applications, used in soft hybrids as well as internal combustion vehicles with stop and go systems, and capacitors for commercial aviation and commercial satellites.

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. Electronic components used to process the electrical power have to operate in close proximity to the Stirling radioisotope generator as well as extreme temperatures. This development addresses two of the largest components in a advance power control unit (ACU). 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. 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. 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. When compared to state of the art metallized film, electrolytics and multilayer ceramic capacitors, the NanolamTM capacitors have up to 10X energy density and 10X specific energy, with excellent capacitance stability with temperature and bias. 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. 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. Potential NASA Applications (Limit 1500 characters, approximately 150 words): There are multiple NASA applications for the NanolamTM capacitors, including power processing units (PPUs) for Hall thruster propulsion units, inverters for roll-out photovoltaic arrays and advance controller units for dynamic power conversion sources, such as Stirling engines. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): The largest NanoLamTM market is DC-link capacitors for inverters used in hybrid vehicles, plug-in-hybrid, all electric, and automotive battery chargers. Other applications include inverters for aerospace applications, PV inverters, LED lighting, wind turbine, rail traction, un-manned aerial vehicles, pulsed power applications and industrial power supplies. Duration: 24