SBIR-STTR Award

Active Signal Technologies, in collaboration with Novacap, Alfred University and Lockheed Martin, proposes in Phase I to build a compact-design 700-V, 50 μF high temperature capacitor module. The module is populated with 1 μF capacitors based on a newly developed sodium bismuth titanate (NBT) dielectric with outstanding electrical performance to 200°C and beyond. Its novel design allows for 115°C coolant flow between the module stack layers, and the geometrical layout of components within the array layers provides for very low ESR and ESL. NBT was selected because of its very low combined temperature and voltage coefficient which gives rise to a net capacitance change < 20% across the band from -40°C to +200°C at full voltage stress. The capacitor is particularly well suited to handling high ripple current because of its low loss (< 2%) and low frequency dispersion to 60 kHz. The proposal addresses key issues of reliability, failure modes, size and cost. New formulations are investigated to increase dielectric constant and reduce component size. In the Phase I Option and Phase II, nano processing techniques will be introduced to reduce intrinsic flaw size, raise breakdown strength and lower sintering temperature to enable the use of base metal electrodes.

Keywords:
Capacitors, Electroceramic, High Temperature, Dielectric, Power Electronics, Bismuth Sodium Titanate, Ferroelectrics

Active Signal Technologies, in collaboration with Novacap, Alfred University and Lockheed Martin, proposes to further develop its high-temperature capacitor technology and deliver multiple 700-V modules to the Army. The modules will be populated with 1-µF capacitors based on a newly-developed sodium bismuth titanate (NBT) dielectric with outstanding electrical performance to 200°C and beyond. While the original design allowed for flow of 115°C coolant between the layers making up the module stack, Phase-I testing demonstrated that the high-temperature capability and low ESR of the NBT capacitor enables operation at 150°C ambient without forced cooling. The NBT dielectric, Type H, was selected for this application because of its very low combined temperature and voltage coefficient which gives rise to a net capacitance change < 20% across the band from -40°C to +200°C at full voltage stress. In Phase II, minor variations on the formulation will be investigated to increase dielectric constant and reduce component size, and sintering studies including nano-processing techniques are introduced to reduce intrinsic flaw size, raise breakdown strength and lower the sintering temperature to enable the use of cheaper electrodes. DC HALT studies will be conducted and a novel 60-kHz life/screening test developed to ensure reliability.

Keywords:
Capacitors, High Temperature, Power Electronics,Sodium Bismuth Titanate, Low Esr, High Frequency