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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

On the Moon to Stay: Challenges Presented to Power Electronics Technology by Sustained Operations on the Lunar Surface

NASA’s Artemis Program seeks not only to return humans to the Moon for the first time since the 1970’s but also to provide the technological basis for infrastructure that will enable permanent and expanding scientific and industrial exploitation of the Lunar surface. The primary purpose of this infrastructure is to generate and distribute power to a diverse and growing range of scientific and industrial assets, and the keys to success for this function are power management and control circuits that are highly reliable and maintainable for a decade of operation in the extreme thermal, radiation, and dust environment of the Lunar surface. While various combinations of wide band gap semiconductors, electronic devices, circuit topologies, and shielding schemes have been successfully developed for mission environments ranging from low Earth orbit to the Jovian system, power management technology has not been optimized to meet the full combination of mission requirements for the Lunar surface. To accomplish this, NASA requests the dedicated focus of the power electronics industry.

semiconductors↗
NASA NTRS1978

Evaluation of induction motor performance using an electronic power factor controller

The concept of reducing the losses in an induction motor by electronically controlling the time interval between the zero crossing of the applied voltage and the zero crossing of the armature current was evaluated. The effect on power losses and power factor of reducing the applied sinusoidal voltages below the rated value was investigated experimentally. The reduction in power losses was measured using an electronic controller designed and built at MSFC. Modifications to the MSFC controller are described as well as a manually controlled electronic device which does not require that the motor be wye connected and the neutral available. Possible energy savings are examined.

Source record↗
DOE OSTI2022

Regrowth and Selective Area Growth of GaN for Vertical Power Electronics

Gallium Nitride (GaN) has a great potential in high-power and high-frequency applications due to its wide energy gap and good transport property. So far all commercial GaN optoelectronic and electronic devices have planar junctions and heterostructures prepared by epitaxial growth. To take the advantage of the merits of GaN material properties, more sophisticated device configurations such as current-aperture vertical electron transistors (CAVETs), junction field-effect transistors (JFETs), and super-junction (SJ) devices require the ability to form in-plane, lateral junctions by selective area doping (SAD). In this project, we explored a novel approach of realizing SAD through selective-area etching (SAE) followed by selective-area growth (SAG).

36 MATERIALS SCIENCE↗
DOE OSTI2021

Noncured Graphene Thermal Interface Materials for High-Power Electronics: Minimizing the Thermal Contact Resistance

We report on experimental investigation of thermal contact resistance, RC, of the noncuring graphene thermal interface materials with the surfaces characterized by different degree of roughness, Sq. It is found that the thermal contact resistance depends on the graphene loading, ξ, non-monotonically, achieving its minimum at the loading fraction of ξ ~15 wt%. Decreasing the surface roughness by Sq~1 μm results in approximately the factor of ×2 decrease in the thermal contact resistance for this graphene loading. The obtained dependences of the thermal conductivity, KTIM, thermal contact resistance, RC, and the total thermal resistance of the thermal interface material layer on ξ and Sq can be utilized for optimization of the loading fraction of graphene for specific materials and roughness of the connecting surfaces. Our results are important for the thermal management of high-power-density electronics implemented with diamond and other wide-band-gap semiconductors.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Regional Manufacturing Cost Structures and Supply Chain Considerations for SiC Power Electronics in Medium Voltage Motor Drives

With the growth in wide bandgap (WBG) semiconductors, specifically Silicon Carbide (SiC), the technology has matured enough to highlight a need to understand the drivers of manufacturing cost, regional manufacturing costs, and plant location decisions. Further, ongoing research and investment, necessitates analytical analysis to help inform development of wide bandgap technologies. The paper explores the anticipated device, module, and motor drive cost at volume manufacturing. It additional outlines the current regional contributors to the supply chain and proposes how the base models can be used to evaluate the cost reduction potential of proposed research advances.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2019

Characterization and Failure Analysis of 650-V Enhancement-Mode GaN HEMT for Cryogenically Cooled Power Electronics

In order to evaluate the feasibility of newly developed gallium nitride (GaN) devices in a cryogenically cooled converter, this article characterizes a 650-V enhancement-mode GaN high-electron mobility transistor (GaN HEMT) at cryogenic temperatures. The characterization includes both static and dynamic behaviors. The results show that this GaN HEMT is an excellent device candidate to be applied in cryogenic-cooled applications. For example, transconductance at cryogenic temperature (93 K) is 2.5 times higher than one at room temperature (298 K), and accordingly, peak di / dt during turn-on transients at cryogenic temperature is around 2 times of that at room temperature. Moreover, the ON-resistance of the channel at the cryogenic temperature is only one-fifth of that at room temperature. The corresponding explanations of performance trends at cryogenic temperatures are also given from the view of semiconductor physics. In addition, several device failures were observed during the dynamic characterization of GaN HEMTs at cryogenic temperatures. Additionally, the ultrafast switching speed-induced high di / dt and dv / dt at cryogenic temperatures amplify the negative effects of parasitics inside the switching loop. Based on failure waveforms, two failure modes were classified, and detailed failure mechanisms caused by ultrafast switching speed are given in this article.

42 ENGINEERING↗
NASA NTRS2019

Characterization and Failure Analysis of 650 V Enhancement-Mode GaN HEMT for Cryogenically-Cooled Power Electronics

In order to evaluate the feasibility of newly developed GaN devices in a cryogenically-cooled converter, this paper characterizes a 650 V enhancement-mode Gallium-Nitride high-electron-mobility transistor (GaN HEMT) at cryogenic temperatures. The characterization includes both static and dynamic behaviors. The results show that this GaN HEMT is an excellent device candidate to be applied in cryogenic-cooled applications. For example, transconductance at cryogenic temperature (93 K) is 2.5 times higher than one at room temperature (298 K), and accordingly, peak di/dt during turn-on transients at cryogenic temperature is around 2 times of that at room temperature. Moreover, the on-resistance of the channel at cryogenic temperature is only one-fifth of that at room temperature. The corresponding explanations of performance trends at cryogenic temperatures are also given from the view of semiconductor physics. In addition, several device failures were observed during the dynamic characterization of GaN HEMTs at cryogenic temperatures. The ultra-fast switching speed induced high di/dt and dv/dt at cryogenic temperatures amplifies the negative effects of parasitics inside the switching loop. Based on failure waveforms, two failure modes were classified, and detailed failure mechanisms caused by ultra-fast switching speed are given in this paper.

Static and dynamic characterization↗
DOE OSTI2025

Thermal Performance of Triply Periodic Minimal Surface Lattice Structures in Single-Phase Dielectric Fluid Cooling of Power Electronics

Additive manufacturing has transformed thermal management by enabling the production of complex, optimized geometries that conventional manufacturing methods cannot achieve. This study investigates the single-phase convective heat transfer performance of gyroid triply periodic minimal surface (TPMS) lattice structures with functional porosity. TPMS structures provide high surface area to volume ratios and are amenable to 3D printing. A gyroid numerical model was created and validated against an existing experimental study with a similar feature size to the investigated geometries. The TPMS structure has a periodic width of 1.6 mm, a length of 10 mm, and a height of 4 mm, with a functional porosity ranging from 0.5 to 0.8, decreasing with distance from the heated surface. Three different flow configurations were examined for an inlet fluid temperature of 70 °C. The inlet velocities range from 0.01 to 1.2 m/s, corresponding to a Reynolds number range of 10–900 with a heat flux of 50 W/cm 2 applied at the base. AmpCool ® AC-110 dielectric fluid (Prandtl number 59.5) was used as the coolant. Thermal performance and friction characteristics were studied for the three flow orientations. The parallel flow configuration was identified as the most efficient for heat removal. A detailed analysis of the numerical results highlights the underlying physics behind the thermal performance differences among the flow configurations.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2018

High Power Electron Gun for Metal Additive Manufacturing Based on Superconducting Technology

E-beam additive manufacturing is a rapidly growingindustry. Electron guns capable of reaching higher energiesand higher average power can enable larger melt pools,higher production speed, and permit broader range ofmaterials for metal additive applications. Such electronguns require technologies beyond those normally achievedwith DC high voltage sources. As an example,superconducting radio frequency (SRF) technology is anoption to achieve higher energy and higher power withexcellent efficiency. However, current SRF technologyrequires complex cryogenic systems to safely handlecryogenics gases or liquids such as Helium. Suchcomplexity severely restricts their usage to R&D facilities.In this talk, we introduce and describe, for the first time, anovel technique based on SRF technology to build a highpower, high energy electron gun for advanced metaladditive manufacturing applications. Our design is based ona technique which eliminates liquid Helium entirely. Ourmethod dramatically reduces the complexity and thusallows building practical, efficient, and modern electronsources for additive manufacturing.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Enabling Technology for Energy Sustainability: Power Electronic Converter Control for Renewables

To ensure high penetration of renewable energy sources into power grids, their interfacing inverters need to be designed to provide grid support functions. Important grid support functions include frequency and voltage support. To this end, the research community has recently invested heavily on grid-forming control pilot projects. Grid forming control aims to replace traditional grid following control, which is based on phase-locked loop and can achieve decoupled real and reactive power control. Here, in this article, we review the state-of-the-art grid following and forming technology and point out some deficiencies in dynamic performance in the widely adopted grid-forming control design. We also examine how to ensure that the vector control capable of decoupled real and reactive power regulation can also be achieved in the grid forming design. This type of design has been prototyped and shown great potential to enable retrofitting of large amounts of grid-following controllers through purely software algorithm update. The technology ensures reliable operation of power grids with high penetration of IBRs, thereby further reducing fossil fueled energy sources and cut down carbon emission.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2018

Impact of Heat Dissipation Profiles on Power Electronics Packaging Design

This work focuses on understanding the thermal impacts of using discrete power devices and limitations of applying conventional thermal design methods. Empirically, a thermal system is designed based on selecting a heat sink with the required thermal resistance from the manufacturer datasheet. This method, as an approximate estimation, has been proven effective as a rough design of Si-based power module. However, wide bandgap (WBG) bare dies bring additional thermal design concerns that have been overlooked. The benefits of WBG devices, such as smaller chip sizes and higher power ratings, on the other hand, lead to thermal concentration issues. Detailed analyses and impacts of the thermal concentration are presented in this paper. Finally, a more accurate model involving Finite Element Analysis (FEA) and Genetic Algorithm optimization is also proposed for a more accurate thermal design.

36 MATERIALS SCIENCE↗
NASA NTRS1989

MCTs and IGBTs - A comparison of performance in power electronic circuits

There is a continuous demand for improvements in the quality of switching power devices, such as higher switching frequency, higher withstand voltage capability, larger current-handling capability, and lower conduction losses. However, for single-conduction-mechanism devices (SCRs, GTOs, BJTs, FETs), possessing all these features is probably unrealizable for physical reasons. An attractive solution appears to be double-mechanism devices, in which the features of both a minority carrier device (BJT or SCR) and a majority carrier device (MOSFET) are embedded. Both IGBTs (insulated-gate bipolar transistors) and MCTs (MOS-controlled thyristors) belong to this family of double-mechanism devices and promise to have a major impact on converter circuit signs. The authors deal with the major features of these two devices, pointing out those that are most critical to the design of converter topologies. In particular, the two devices have been tested both in a chopper and in two resonant link converter topologies, and the experimental results are reported.

Sul, S. K.↗