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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 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Analysis and performance of paralleling circuits for modular inverter-converter systems

As part of a modular inverter-converter development program, control techniques were developed to provide load sharing among paralleled inverters or converters. An analysis of the requirements of paralleling circuits and a discussion of the circuits developed and their performance are included in this report. The current sharing was within 5.6 percent of rated-load current for the ac modules and 7.4 percent for the dc modules for an initial output voltage unbalance of 5 volts.

Birchenough, A. G.↗
NASA NTRS1975

Research study on multi-KW DC distribution system

Power distribution system noise and transient stress on switchgear in large space vehicle power systems were investigated in terms of the effect of flight designs of long power distribution cables on load interface EMI requirements. A fifty meter cable pair was simulated to study interactions between the cable, load, and power source terminations. Power system noise characteristics were evaluated based on current spacecraft data, interface hardware filter designs, and power cable parameters. Parametric approaches were defined for evaluating switching transients at various distribution voltage levels. It is concluded that the state-of-the-art semiconductor switches represent a viable approach toward the implementation of power system design with distribution voltages of 120 VDC or less. The interface definition and design for the bus control unit was updated to be consistent with the established requirements.

Berkery, E. A.↗
NASA NTRS1985

Double-injection, deep-impurity switch development

The overall objective of this program was the development of device design and process techniques for the fabrication of a double-injection, deep-impurity (DI) sup 2 silicon switch that operates in the 2-10 kV range with conduction current values of 5 A at 2 kV and 1 A at 10 kV. Other major specifications include a holding voltage of 10 V with no gate current, 10 microsec switching time, and power dissipation of 50 W at 75 C. It was decided to concentrate on the lateral circular devices in order to optimize the gold diffusion. This resulted in devices that are much better switches (approx.1 micro sec switching time), and in a gold diffusion process that is much more controllable than those previously developed. Some results with injection-gated devices were also obtained. The current conduction for V less than VT was analyzed and seen to agree, for the most part, with Lampert's theory. Various sections of this report describe the device designs, wafer-processing techniques, and various measurements which include ac and dc characteristics and four-point probe.

Whitson, D. W.↗
NASA NTRS2003

Cryogenic Evaluation of an Advanced DC/DC Converter Module for Deep Space Applications

DC/DC converters are widely used in power management, conditioning, and control of space power systems. Deep space applications require electronics that withstand cryogenic temperature and meet a stringent radiation tolerance. In this work, the performance of an advanced, radiation-hardened (rad-hard) commercial DC/DC converter module was investigated at cryogenic temperatures. The converter was investigated in terms of its steady state and dynamic operations. The output voltage regulation, efficiency, terminal current ripple characteristics, and output voltage response to load changes were determined in the temperature range of 20 to -140 C. These parameters were obtained at various load levels and at different input voltages. The experimental procedures along with the results obtained on the investigated converter are presented and discussed.

Elbuluk, Malik E.↗
NASA NTRS2010

Integration Assessment of Visiting Vehicle Induced Electrical Charging of the International Space Station Structure

The International Space Station (ISS) undergoes electrical charging in low Earth orbit (LEO) due to positively biased, exposed conductors on solar arrays that collect electrical charges from the space plasma. Exposed solar array conductors predominately collect negatively charged electrons and thus drive the metal ISS structure electrical ground to a negative floating potential (FP) relative to plasma. This FP is variable in location and time as a result of local ionospheric conditions. ISS motion through Earth s magnetic field creates an addition inductive voltage up to 20 positive and negative volts across ISS structure depending on its attitude and location in orbit. ISS Visiting Vehicles (VVs), such as the planned Orion crew exploration vehicle, contribute to the ISS plasma charging processes. Upon physical contact with ISS, the current collection properties of VVs combine with ISS. This is an ISS integration concern as FP must be controlled to minimize arcing of ISS surfaces and ensure proper management of extra vehicular activity crewman shock hazards. This report is an assessment of ISS induced charging from docked Orion vehicles employing negatively grounded, 130 volt class, UltraFlex (ATK Space Systems) solar arrays. To assess plasma electron current collection characteristics, Orion solar cell test coupons were constructed and subjected to plasma chamber current collection measurements. During these tests, coupon solar cells were biased between 0 and 120 V while immersed in a simulated LEO plasma. Tests were performed using several different simulated LEO plasma densities and temperatures. These data and associated theoretical scaling of plasma properties, were combined in a numerical model which was integrated into the Boeing Plasma Interaction Model. It was found that the solar array design for Orion will not affect the ISS FP by more than about 2 V during worst case charging conditions. This assessment also motivated a trade study to determine acceptable plasma electron current levels that can be collected by a single or combined fleet of ISS-docked VVs.

Kramer, Leonard↗
DOE OSTI2022

The Demonstration of Power over Ethernet (PoE) Technologies in Commercial and Institutional Buildings

Power over Ethernet (PoE) technologies are currently ubiquitous in offices in the form of phones, access points, and IP security cameras. They are systems that are familiar to and managed by on-site IT staff. As low voltage DC-power capabilities have increased with the advancement of IT network switches within offices, PoE devices are now being integrated across additional building systems, including lighting, computers, and HVAC controls. The connection of PoE devices to network switches offers the opportunity for energy monitoring and management to be performed through IT network management software. Data and results from technology validations of PoE equipment remain very limited. This lack of information hinders expansion of PoE as an energy management strategy as its benefits and challenges have been insufficiently quantified in real-world scenarios. This final report presents the findings of a DOE/State of Minnesota-funded project that demonstrated and assessed the energy and non-energy benefits of Power over Ethernet (PoE) technologies at six sites: two offices, three schools, and a hotel. The goals of the demonstrations were to: (1) assess the receptiveness of commercial and institutional markets to these new technologies, (2) demonstrate the feasibility of PoE technologies within standard design/construction practices and commercial codes, (3) assess the energy and cost savings opportunities of these technologies, (4) provide energy management opportunities where not typically available, and (5) formulate approaches to spur adoption of these technologies in the marketplace.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1981

Straight and chopped DC performance data for a General Electric 5BY436A1 DC shunt motor with a General Electric EV-1 controller

Both straight and chopped dc motor performance data for a General Electric 5BY436A1 motor with a General Electric EV-1 controller is presented in tabular and graphical formats. Effects of motor temperature and operating voltage are also shown. The maximum motor efficiency is approximately 85% at low operating temperatures in the straight dc mode. Chopper efficiency can be assumed to be 95% under all operating conditions. For equal speeds, the motor operated in the chopped mode develops slightly more torque and draws more current than it does in the straight mode.

Edie, P. C.↗
DOE OSTI2021

SiC-Based 5-kV Universal Modular Soft-Switching Solid-State Transformer (M-S4T) for Medium-Voltage DC Microgrids and Distribution Grids

Medium-voltage DC (MVDC) grids are attractive for electric aircraft and ship power systems, battery energy storage system (BESS), fast charging electric vehicle (EV), etc. Such EV or BESS applications need isolated bidirectional MVDC to LVDC or LVAC converters. However, the existing Si-based solutions cannot fulfill the requirements of a high-efficiency and robust converter for MVDC grids. This paper presents a 5 kV SiC-based universal modular solid-state transformer (SST). This universal current-source SST can interface either a LVAC or LVDC grid with a MVDC grid in single-stage power conversion, while the conventional dual active bridge (DAB) converter needs an additional inverter. The proposed SST module using 3.3 kV SiC MOSFETs and diodes is bidirectional and can serve as a building block in series or parallel for higher-voltage higher-power systems. The topology of each module is based on the soft-switching solid-state transformer (S4T) with reduced conduction loss, which features reduced EMI through controlled dv/dt, and high efficiency with full-range ZVS for main devices and ZCS for auxiliary devices. Operation principle of the modular S4T (M-S4T), capacitor voltage balancing control between the cascaded modules, design of components including a medium-voltage (MV) medium-frequency transformer (MFT) to realize a 50 kVA 5 kV DC to 600 V DC or 480 V AC M-S4T are presented. Importantly, the MV MFT prototype achieves very low leakage inductance (0.13%) and 15 kV insulation with coaxial cables and nanocrystalline cores. Here, the proposed universal modular SST is compared against the DAB solution and verified with DC-DC and DC-AC simulation and 4 kV experimental results. Significantly, the MV experimental results of a modular DC transformer with each module at MVDC are rarely covered in the literature and reported for the first time.

14 SOLAR ENERGY↗
DOE OSTI2020

Spin Rectification and Electrically Controlled Spin Transport in Molecular-Ferroelectrics-Based Spin Valves

We report a spin-rectification effect in a spin-valve structure consisting of ferroelectric croconic acid (C 5 H 2 O 5 ) sandwiched between ferromagnetic electrodes La 0.7 Sr 0.3 MnO 3 and Co, which can be switched between a high-resistance (off ) and a low-resistance (on) state by a poling voltage. In the off state, the magnetoresistance (MR) sign reverses with the measurement voltage with a 0.1-V offset, suggesting a spin-rectification behavior, while in the on state the MR remains negative. These observations can be understood in terms of electrically controlled interfacial energy-band alignment either from the electrostatic effect or from the interfacial redox process. In conclusion, the observed spin-rectification effect suggests thepossibility of diodelike devices for spin-polarized current.

36 MATERIALS SCIENCE↗
NASA NTRS2006

Junction-to-Case Thermal Resistance of a Silicon Carbide Bipolar Junction Transistor Measured

Junction temperature of a prototype SiC-based bipolar junction transistor (BJT) was estimated by using the base-emitter voltage (V(sub BE)) characteristic for thermometry. The V(sub BE) was measured as a function of the base current (I(sub B)) at selected temperatures (T), all at a fixed collector current (I(sub C)) and under very low duty cycle pulse conditions. Under such conditions, the average temperature of the chip was taken to be the same as that of the temperature-controlled case. At increased duty cycle such as to substantially heat the chip, but same I(sub C) pulse height, the chip temperature was identified by matching the V(sub BE) to the thermometry curves. From the measured average power, the chip-to-case thermal resistance could be estimated, giving a reasonable value. A tentative explanation for an observed bunching with increasing temperature of the calibration curves may relate to an increasing dopant atom ionization. A first-cut analysis, however, does not support this.

Niedra, Janis M.↗
NASA NTRS2012

Design and Operation of the Planetary In-Situ Capillary Electrophoresis System (PISCES)

The PISCES instrument is a portable, miniature, modular instrument designed to analyze organic molecular signatures of life. PISCES uses microcapillary electrophoresis (μCE) with laser-induced fluorescence detection (LIFD) to analyze fluorescently-labeled analytes prepared on a multi-layer microfluidic chip. As a modular instrument composed of five independently functioning units, each module can be easily detached from the system and used for subsystem testing in different environments, e.g. low temperature. The pneumatic module contains mechanical and electrical components necessary to control pneumatically-actuated valves for on-chip sample processing. A prototype LabVIEW program and two custom printed circuit boards (PCBs) operate the pneumatics module using an Arduino microcontroller, and a tentative design for the module’s housing has been developed. The high-voltage module contains circuitry required to apply varying electrical potentials to the electrophoretic channel of the microdevice. Work is currently being done to design the circuit and PCB for this module in collaboration with our SBIR partners at Los Gatos Research. The optical electronics module contains the spectrometer, laser, and laser power supply. The mounting components for the electronics and housing for the module have been designed, assembled, and tested. The optical module contains optical components to focus the laser to a 20μm spot in the center of the electrophoretic channel.The housing for this module has been designed and assembled with the aligned optical components inside.

Willis, Peter A.↗
NASA NTRSDate not supplied

A Call To Action To Engage The Community To Meet The Challenges That Must Be Tackled To Make Electrified Aircraft Propulsion Real

Technology risk reduction is essential, as it is necessary to demonstrate the potential of Electrified Aircraft Propulsion (EAP). However, more is needed for implementation. The industry is leading EAP by developing a diverse community of novel vehicles from short-haul, small, urban-focused electric vertical takeoff and landing (eVTOL) to regional air mobility (RAM) and hybrid-electric, single-aisle transport category airplanes. There are a variety of novel EAP technologies for each of these novel vehicles. And the industry is not only looking at novel technology to advance the state of the art. Instead, the industry is looking to certify these novel aircraft through their regulatory authorities, such as the US Federal Aviation Administration (FAA), the European Union Aviation Safety Authority (EASA), Transport Canada Civil Aviation (TCCA), and Brazil’s Agência Nacional de Aviação Civil (National Civil Aviation Agency, ANAC), as well as other regulatory authorities. The NASA Electrified Powertrain Flight Demonstration (EPFD) project has partnered with two industry partners to advance integrated MW-class powertrain system technology demonstration that includes an assessment of their regulatory and standards gaps in their technology. The EPFD has conducted a generic regulatory gap analysis of hybrid electric engines that aligns with the industry partners’ efforts. The EPFD regulations and standards team is integrated into the industry standards community. The international industry standards community is wrestling with critical key challenges to certification. While some certification elements are proprietary, several technology elements cut across company propriety in aircraft engines (US 14 CFR Part 33 and EASA CS-E, regulations that only reflect reciprocating and turbine engines). The approach that several of these regulatory authorities have taken is to collaborate to address their challenges. The Certification Management Team (CMT) consists of the EASA, FAA, TCCA, and ANAC, and they have begun to address common questions, such as the Loss of Power Control (LOPC) for electric engines. They have reached out to the standards community to seek answers. The industry standards development organizations (SDO) have also looked ahead to address current regulations and standards gaps. The ASTM has built key committees in its ASTM F44 General Aviation Committee and F39 Aircraft Systems Committee. The SAE has established the E-40 Electric Propulsion and AE-10 High Voltage committees.

Standards↗
NASA NTRSDate not supplied

A Call To Action To Engage The Community To Meet The Challenges That Must Be Tackled To Make Electrified Aircraft Propulsion Real

Technology risk reduction is essential, as it is necessary to demonstrate the potential of Electrified Aircraft Propulsion (EAP). However, more is needed for implementation. The industry is leading EAP by developing a diverse community of novel vehicles from short-haul, small, urban-focused electric vertical takeoff and landing (eVTOL) to regional air mobility (RAM) and hybrid-electric, single-aisle transport category airplanes. There are a variety of novel EAP technologies for each of these novel vehicles. And the industry is not only looking at novel technology to advance the state of the art. Instead, the industry is looking to certify these novel aircraft through their regulatory authorities, such as the US Federal Aviation Administration (FAA), the European Union Aviation Safety Authority (EASA), Transport Canada Civil Aviation (TCCA), and Brazil’s Agência Nacional de Aviação Civil (National Civil Aviation Agency, ANAC), as well as other regulatory authorities. The NASA Electrified Powertrain Flight Demonstration (EPFD) project has partnered with two industry partners to advance integrated MW-class powertrain system technology demonstration that includes an assessment of their regulatory and standards gaps in their technology. The EPFD has conducted a generic regulatory gap analysis of hybrid electric engines that aligns with the industry partners’ efforts. The EPFD regulations and standards team is integrated into the industry standards community. The international industry standards community is wrestling with critical key challenges to certification. While some certification elements are proprietary, several technology elements cut across company propriety in aircraft engines (US 14 CFR Part 33 and EASA CS-E, regulations that only reflect reciprocating and turbine engines). The approach that several of these regulatory authorities have taken is to collaborate to address their challenges. The Certification Management Team (CMT) consists of the EASA, FAA, TCCA, and ANAC, and they have begun to address common questions, such as the Loss of Power Control (LOPC) for electric engines. They have reached out to the standards community to seek answers. The industry standards development organizations (SDO) have also looked ahead to address current regulations and standards gaps. The ASTM has built key committees in its ASTM F44 General Aviation Committee and F39 Aircraft Systems Committee. The SAE has established the E-40 Electric Propulsion and AE-10 High Voltage committees.

Standards↗
DOE OSTI2020

Making Better Use of On-Site PV Generation: Direct Distribution of DC Power in Buildings

With the increasing availability of Direct Current (DC) power from on-site solar systems, building designers now have the option of direct distribution of DC power to energy storage systems and end-use loads such as lighting, electronics, and motors. Research shows that direct-DC can reduce building distribution losses by 5-15%, while improving power reliability. A readily available way to implement direct-DC distribution is Power over Ethernet (PoE), which typically has provided low-voltage DC to power office equipment such as WiFi access points. With recent updates to the PoE standard, equipment such as network-controlled LED lighting, thin client and computer workstations, HVAC controllers, fans, motors, and actuators can now be powered by PoE and are commercially available. This paper presents results from a DOE-funded project that is demonstrating PoE technologies and describes a DC modeling and design tool that is intended to help building designers properly evaluate and design DC distribution systems in buildings. The tool provides designers of DC power systems with estimates of both power system losses and indirect effects on building heating and cooling. The results of this research demonstrate that the design methods and products are available to implement DC power in buildings today.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

Ultrathin silicon oxide prepared by in-line plasma-assisted N 2 O oxidation (PANO) and the application for n-type polysilicon passivated contact

We develop a plasma-assisted nitrous-oxide (N 2 O) gas oxidation (PANO) method to prepare the ultrathin silicon oxide (SiO x ) for polysilicon (poly-Si) passivated contact. The effects of preparation conditions, including the substrate temperature, processing time, and plasma power, are studied. Afterwards, we integrate the PANO SiO x into the polysilicon passivated contact and optimize the passivation and contact performances. Excellent surface passivation with the n-type poly-Si and PANO SiO x on the n-type c-Si wafer is achieved by 880 °C annealing, which shows competitive passivation quality to the one with NASO SiO x . Champion implied open-circuit voltage (iV oc ) and single-sided recombination saturated current (J 0 ) reach 730 mV and 4.3 fA/cm 2 after crystallization; and they are further improved to 747 mV and 2.0 fA/cm 2 (3 × 10 15 cm -3 ) after subsequent AlO x /SiN x hydrogenation. Using transmission electron microscopy (TEM), we find that the thickness of PANO SiO x ranges 1.1–2.4 nm and the controlled nitric acid oxidized SiO x (NAOS) ranges 1.3–1.8 nm. The contact resistivity (ρ c ) is typically <10 mΩ cm 2 with the annealing temperature of >820 °C. Also, the crystallinity, phosphorous in-diffusion profile, and current-leaking density of the passivated contacts are investigated. In general, the PANO SiO x and in-situ doping amorphous silicon precursor can be fabricated in one PECVD system without additional equipment or transfer procedures, which is favorable for the high-efficiency, low-cost industrial manufacture.

14 SOLAR ENERGY↗
NASA NTRS1976

Silicon solar cells from transition metal doped Czochralski and web crystals

The influence of metallic impurities on solar cell characteristics has been examined to establish the cost sensitive purity versus performance trade-offs. Solar cells were fabricated on 2 to 4 ohm-cm p-type substrates obtained by Czochralski and dendritic web growth processes. Controlled amounts of metallic impurities were introduced into the melt during growth and included Fe, Cr, Mn, Ni, Cu, Ti, V, Zr, Mg, Zn, and Al. Impurity concentrations in the crystals were determined using emission and mass spectrographic techniques and in some cases by neutron activation analysis. The solar cells were characterized by means of a computer program to curve-fit measured voltage-current data. The principal effect of the added impurities is a degradation of lifetime and diffusion length.

Davis, J. R.↗
NASA NTRS1977

Annual Conference on Nuclear and Space Radiation Effects, 14th, College of William and Mary, Williamsburg, Va., July 12-15, 1977, Proceedings

Topics related to processing and hardness assurance are considered, taking into account the radiation hardening of CMOS technologies, technological advances in the manufacture of radiation-hardened CMOS integrated circuits, CMOS hardness assurance through process controls and optimized design procedures, the application of operational amplifiers to hardened systems, a hard off-the-shelf SG1524 pulse width modulator, and the gamma-induced voltage breakdown anomaly in a Schottky diode. Basic mechanisms are examined, giving attention to chemical and structural aspects of the irradiation behavior of SiO2 films on silicon, experimental observations of the chemistry of the SiO2/Si interface, leakage current phenomena in irradiated SOS devices, the avalanche injection of holes into SiO2, the low-temperature radiation response of Al2O3 gate insulators, and neutron damage mechanisms in silicon at 10 K. Other subjects discussed are related to radiation effects in devices and circuits, space radiation effects, and aspects of simulation, energy deposition, and dosimetry.

Stahl, R. H.↗