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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4

Europe’s energy policy based on large-scale use of renewables most likely will require supplemental power supplies to balance their electrical power systems

Political decisions toward an increased role for renewable energy sources (wind & solar) in Europe will have an impact on the functioning of the electrical power systems that will have to be offset due to the inherent intermittent nature of renewable sources. The offset can be accomplished either through increasing non-renewable energy supply and production from other means, including purchasing Russian piped natural gas and LNG, or decreasing demand by curtailing power consumption. Europe likely will also need increased energy supplies to cover reduced gas production in the North Sea and Netherlands. Also, expected disconnection of Baltic states from the BRELL (Belarus-Russia-EstoniaLatvia-Lithuania) grid will force these countries to acquire electricity from Europe, resulting in increased demands on the European power grid that will require additional capacity to offset.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Closed-cycle power supply for fluidic control systems

Power supply utilizes small quantities of two-phase fluid of suitable thermodynamic properties for circulation in a capillary-pumped heat transfer loop. Fluid is vaporized in evaporator, passed through fluidic system load, condensed, pumped by multistage capillary pump, and returned to the evaporator.

Fiet, O.↗

Improving Power-Supply Regulation for Pulsed Loads

Power supply voltage-regulator circuit speeds up response to sudden load changes. As load increases, additional feedback path is enabled. Path bypasses and provides faster loop response than normal feedback path. Steady-state instability due to faster loop response avoided by progressively disabling bypass loop and allowing normal feedback path to take over.

Gulick, C. R.↗

Switching System for Redundant Power Supplies

Load-transfer unit connects airborne computer to standby power supply in case primary supply fails. Concept adaptable to systems in which power interruptions cannot be tolerated; for example, computers with volatile memories, safety equipment, and precise timers. Load-transfer unit monitors voltages and load current. Microprocessor controls transistor switches that connect load to whichever power supply has highest priority and correct voltage.

Bradford, M.↗

Multi-reactor configurations for multi-megawatt spacecraft power supplies

Several conceptual designs for a multimegawatt space nuclear power supply system were developed on the basis of hardware and technology from the existing multihundred kilowatt-class SP-100 reactor program. It is shown that net power outputs in the multimegawatt range can be achieved by using a modular multireactor configuration of several SP-100-derived nuclear power supplies. A variety of geometries were examined for their applicability to the multireactor configuration, showing that modular multireactor systems have the advantage of an increased redundancy in the power system, as compared with a single-reactor system, allowing higher reliabilities than those achievable with single-reactor systems. Results are presented on the Mars Cargo Mission analysis, showing that modularity allows the option of redeployment of power systems in Mars and facilitates refurbishment and turnaround of NEP transfer vehicles.

George, Jeffrey A.↗

Performance Characterization of a Lithium-ion Gel Polymer Battery Power Supply System for an Unmanned Aerial Vehicle

Unmanned aerial vehicles (UAVs) are currently under development for NASA missions, earth sciences, aeronautics, the military, and commercial applications. The design of an all electric power and propulsion system for small UAVs was the focus of a detailed study. Currently, many of these small vehicles are powered by primary (nonrechargeable) lithium-based batteries. While this type of battery is capable of satisfying some of the mission needs, a secondary (rechargeable) battery power supply system that can provide the same functionality as the current system at the same or lower system mass and volume is desired. A study of commercially available secondary battery cell technologies that could provide the desired performance characteristics was performed. Due to the strict mass limitations and wide operating temperature requirements of small UAVs, the only viable cell chemistries were determined to be lithium-ion liquid electrolyte systems and lithium-ion gel polymer electrolyte systems. Two lithium-ion gel polymer cell designs were selected as candidates and were tested using potential load profiles for UAV applications. Because lithium primary batteries have a higher specific energy and energy density, for the same mass and volume allocation, the secondary batteries resulted in shorter flight times than the primary batteries typically provide. When the batteries were operated at lower ambient temperatures (0 to -20 C), flight times were even further reduced. Despite the reduced flight times demonstrated, for certain UAV applications, the secondary batteries operated within the acceptable range of flight times at room temperature and above. The results of this testing indicate that a secondary battery power supply system can provide some benefits over the primary battery power supply system. A UAV can be operated for hundreds of flights using a secondary battery power supply system that provides the combined benefits of rechargeability and an inherently safer chemistry.

Reid, Concha M.↗

Physical model and experimental results of cathode erosion related to power supply ripple

This paper discusses the physical effects of power supply ripple on cathode erosion and cathode arc attachment in a water-cooled, 30 kW nitrogen arcjet. Experimental results are presented for 2 percent thoriated tungsten, which show that the long-term cathode erosion rate is a decreasing function of current ripple over the range 1-13 percent. Above this range, the cathode discharge becomes unstable, and the erosion rate rapidly increases. A qualitative model of this effect is given in terms of a magnetically induced radial motion of the arc column, and an overall increase in the cathode spot radius due to the higher peak current associated with higher ripple. The most important effect of power supply ripple is therefore shown to be its ability to collectively drive the cathode attachment away from the cathode center. This leads to an increase in the cathode attachment area, and a subsequent decrease in the cathode erosion rate.

Harris, W. J.↗

Simplified power supplies for ion thrusters

The initial development and demonstration of power supplies with an order of magnitude reduction in parts count, leading to increased reliability at lower weight, while still maintaining thrust system performance are discussed. Two new self-regulating keeper power supply circuits were developed and tested. One supply comprises 14 parts and uses an input voltage range of 18 to 36 volts, the other operates from 200 to 400 volts and requires 22 components. A technique for controlling heater power is also demonstrated.

Gruber, R. P.↗

Expert systems for space power supply - Design, analysis, and evaluation

The feasibility of applying expert systems to the conceptual design, analysis, and evaluation of space power supplies in particular, and complex systems in general is evaluated. To do this, the space power supply design process and its associated knowledge base were analyzed and characterized in a form suitable for computer emulation of a human expert. The existing expert system tools and the results achieved with them were evaluated to assess their applicability to power system design. Some new concepts for combining program architectures (modular expert systems and algorithms) with information about the domain were applied to create a 'deep' system for handling the complex design problem. NOVICE, a code to solve a simplified version of a scoping study of a wide variety of power supply types for a broad range of missions, has been developed, programmed, and tested as a concrete feasibility demonstration.

Cooper, Ralph S.↗

Fail-Safe Synchronizer For Power Supply

Fail-safe synchronizer feeds external synchronizing signal to switching power supply. When external synchronizing signal lost, it feeds signal from relaxation oscillator to power supply.

Katz, Richard B.↗

Prognostic health monitoring in switch-mode power supplies with voltage regulation

The system includes a current injection device in electrical communication with the switch mode power supply. The current injection device is positioned to alter the initial, non-zero load current when activated. A prognostic control is in communication with the current injection device, controlling activation of the current injection device. A frequency detector is positioned to receive an output signal from the switch mode power supply and is able to count cycles in a sinusoidal wave within the output signal. An output device is in communication with the frequency detector. The output device outputs a result of the counted cycles, which are indicative of damage to an a remaining useful life of the switch mode power supply.

Hofmeister, James P↗

Advanced modular power supplies for Space Station Freedom

Viewgraphs and discussion on advanced modular power supplies for Space Station Freedom are presented. Topics covered include concept and characteristics; user power supply applications; and bulk converter application.

Krauthamer, S.↗

10 kV Class 14 MHz Isolated Power Supply

This paper presents a single-switch based isolated power supply, utilizing a PCB based core-less transformer to achieve high inter-winding isolation and low common-mode capacitance. Detailed design procedure, considering the transformer to achieve full range ZVS, minimize voltage stress and minimize RMS currents is presented. The proposed methodology is experimentally validated at 14 MHz, with a load variation of 10:1 in output power and a maximum output power of 4 W. The proposed power supply is useful in applications such as MV gate drives and sensors.

Tessaro Andrade, Elvey [ORNL] (ORCID:0009000225919↗

Thermal control of power supplies with electronic packaging techniques

The analysis, design, and development work to reduce the weight and size of a standard modular power supply with a 350 watt output was summarized. By integrating low cost commercial heat pipes in the redesign of this power supply, weight was reduced by 30% from that of the previous design. The temperature was also appreciably reduced, increasing the environmental capability of the unit. A demonstration unit with a 100 watt output and a 15 volt regulator module, plus simulated output modules, was built and tested to evaluate the thermal performance of the redesigned power supply.

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