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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 199 records · Page 11

All sources NASA NTRS DOE OSTI

NASA NTRS2013

Benefits of Hybrid-Electric Propulsion to Achieve 4x Increase in Cruise Efficiency for a VTOL Aircraft

Electric propulsion enables radical new vehicle concepts, particularly for Vertical Takeoff and Landing (VTOL) aircraft because of their significant mismatch between takeoff and cruise power conditions. However, electric propulsion does not merely provide the ability to normalize the power required across the phases of flight, in the way that automobiles also use hybrid electric technologies. The ability to distribute the thrust across the airframe, without mechanical complexity and with a scale-free propulsion system, is a new degree of freedom for aircraft designers. Electric propulsion is scale-free in terms of being able to achieve highly similar levels of motor power to weight and efficiency across a dramatic scaling range. Applying these combined principles of electric propulsion across a VTOL aircraft permits an improvement in aerodynamic efficiency that is approximately four times the state of the art of conventional helicopter configurations. Helicopters typically achieve a lift to drag ratio (L/D) of between 4 and 5, while the VTOL aircraft designed and developed in this research were designed to achieve an L/D of approximately 20. Fundamentally, the ability to eliminate the problem of advancing and retreating rotor blades is shown, without resorting to unacceptable prior solutions such as tail-sitters. This combination of concept and technology also enables a four times increase in range and endurance while maintaining the full VTOL and hover capability provided by a helicopter. Also important is the ability to achieve low disc-loading for low ground impingement velocities, low noise and hover power minimization (thus reducing energy consumption in VTOL phases). This combination of low noise and electric propulsion (i.e. zero emissions) will produce a much more community-friendly class of vehicles. This research provides a review of the concept brainstorming, configuration aerodynamic and mission analysis, as well as subscale prototype construction and flight testing that verifies transition flight control. A final down-selected vehicle is also presented.

Fredericks, William J.↗

NASA NTRS2023

Design Studies on Mechanically Geared, Magnetically Geared, and Direct Drive Drivetrains for UAM Applications

Urban air mobility vehicles require high reliability and high performance electric motor drive trains. In this paper, a design optimization study is carried out to compare mechanically geared, magnetically geared, and direct drive motor drivetrain topology achievable performance in a 100 kW hover power quad rotor propulsor application. Design studies are carried out accounting for a nominal mission profile. Studies are carried out assuming constant propulsor rotor RPMs of 400, 1000, 2000, and 3000 RPM. Results show that mechanically geared drives are the lightest at all RPMs but their weight benefit over direct drive and magnetically geared decays with increased rotor RPM. Direct drive is shown to always achieve the highest efficiency due to its lower motor speed resulting in low electrical frequencies. Magnetically geared drivetrains are shown to need some requirement refinement or technology improvement to provide significant benefit over direct drive drivetrains.

Thomas Tallerico↗

NASA NTRS2023

Design Studies on Mechanically Geared, Magnetically Geared, and Direct Drive Drivetrains for UAM Applications

Thomas Tallerico↗

NASA NTRS2015

Airvolt Aircraft Electric Propulsion Test Stand

Development of an electric propulsion test stand that collects high-fidelity data of motor, inverter, and battery system efficiencies; thermal dynamics; and acoustics independent of manufacturer reported values will improve understanding of electric propulsion systems to be used in future aircraft. A buildup approach to this development reveals new areas of research and best practices in testing, and attempts to establish a standard for testing these systems.

propulsion↗

DOE OSTI2023

Thermal Analysis of Liquid and Air Cooling of High-Power-Density Integrated Motor Drives

Thermal management is a crucial aspect in the design of motor and drive systems. This paper introduces a coordinated cooling approach utilizing both liquid and air to enhance the integrated motor drive's power density. The proposed solution incorporates a shared water jacket to cool both the machine and power electronics, combined with forced air ventilation for the end windings and rotor. This approach is structurally simpler, less expensive, and more effective than conventional non-interacting cooling schemes. The paper addresses the modeling of key thermal features and nonlinearities including material anisotropy, contact thermal resistance, and uneven winding loss distributions. In addition, this study utilizes a more detailed model of the loss distribution among the winding turns in each slot that delivers a higher level of accuracy. Finite Element Analysis (FEA) results demonstrate the effectiveness of the integrated cooling system for efficiently cooling the designed integrated motor drive system.

42 ENGINEERING↗

NASA NTRS1980

Determination of efficiencies, loss mechanisms, and performance degradation factors in chopper controlled dc vehical motors. Section 1: Test program results and recommendations

The conventional series motor model is discussed as well as procedures for obtaining, by test, the parameters necessary for calculating performance and losses. The calculated results for operation from ripple free DC are compared with observed test results, indicating approximately 5% or less error. Experimental data indicating the influence of brush shift and chopper frequency are also presented. Both factors have a significant effect on the speed and torque relationships. The losses and loss mechanisms present in a DC series motor are examined and an attempt is made to evaluate the added losses due to harmonic currents and fluxes. Findings with respect to these losses is summarized.

Hamilton, H. B.↗

NASA NTRS1980

Determination of efficiencies, loss mechanisms, and performance degradation factors in chopper controlled dc vehical motors. Section 2: The time dependent finite element modeling of the electromagnetic field in electrical machines: Methods and applications

The time dependent solution of the magnetic field is introduced as a method for accounting for the variation, in time, of the machine parameters in predicting and analyzing the performance of the electrical machines. The method of time dependent finite element was used in combination with an also time dependent construction of a grid for the air gap region. The Maxwell stress tensor was used to calculate the airgap torque from the magnetic vector potential distribution. Incremental inductances were defined and calculated as functions of time, depending on eddy currents and saturation. The currents in all the machine circuits were calculated in the time domain based on these inductances, which were continuously updated. The method was applied to a chopper controlled DC series motor used for electric vehicle drive, and to a salient pole sychronous motor with damper bars. Simulation results were compared to experimentally obtained ones.

Hamilton, H. B.↗

DOE OSTI2022

High Efficiency Heat Pumps Can Pave the Path for Building Decarbonization in Cold Climates: Preprint

Heat pumps play an instrumental role in buildings decarbonization strategies. Recent advances in heat pump systems employ variable-speed compressor technology and electronically commutated fan motors. Inherently, the heating capacity and efficiency of heat pumps decrease with falling outdoor temperatures. Compared to single-speed heat pumps, variable speed systems can maintain higher heating and cooling efficiencies over a wider range of outdoor temperatures. The goal of this multi-phase project was to determine the energy savings of a high efficiency, variable-speed, air-source, split system heat pump designed for cold climate applications. The first project phase was to evaluate the performance of the heat pump in the laboratory under varying outdoor conditions in heating and cooling modes. The second phase was to translate the laboratory-measured performance into lookup tables for EnergyPlus hourly building simulation engine. Then, two sets of annual building simulations were performed using typical meteorological year weather from the Chicago-O'Hare airport for three different building types (a single-family residence, a strip mall, and a low-rise office building). The first set simulated a standard efficiency heat pump while the second set utilized the phase two performance tables to model a high efficiency heat pump. The high efficiency heat pump produced significant annual heating energy savings in all three buildings. The variable speed compressor and fan control also contributed to cooling energy savings. The simulated annual energy savings ranged from 22% to 35% over their respective baseline. The project's findings helped a Midwest electric utility, Commonwealth Edison (ComEd), design new incentives around high efficiency heat pumps.

cold climate heat pump↗

NASA NTRS1975

Variable frequency inverter for ac induction motors with torque, speed and braking control

A variable frequency inverter was designed for driving an ac induction motor which varies the frequency and voltage to the motor windings in response to varying torque requirements for the motor so that the applied voltage amplitude and frequency are of optimal value for any motor load and speed requirement. The slip frequency of the motor is caused to vary proportionally to the torque and feedback is provided so that the most efficient operating voltage is applied to the motor. Winding current surge is limited and a controlled negative slip causes motor braking and return of load energy to a dc power source.

Nola, F. J.↗

NASA NTRSDate not supplied

Design of a High Power Density, High Efficiency, Low THD 250kW Converter for Electric Aircraft

A high efficiency, high power density, low distortion 250kW motor controller is being developed at NASA Glenn Research Center. Future electric aircraft require motor controllers which achieve the needed key performance parameters required to show benefit in increasing overall aircraft efficiency. Through a combination of carefully considered electrical topological choices and through the use of recent advancements in power switches and magnetic materials, a converter is designed which meets these requirements. A multilevel and interleaved converter architecture is chosen to meet the voltage, current, and THD requirements. The enclosure and thermal designs meet their weight targets and enable high altitude operation.

Matthew Granger↗

DOE OSTI2023

Comparative Life Cycle Assessment of Injection Molded and Big Area Additive Manufactured NdFeB Bonded Permanent Magnets

Permanent magnets are expected to play a crucial role in the realization of the clean economy. In particular, the neodymium-iron-boron (Nd2Fe14B or NdFeB) magnets, which have the highest energy density among rare earth permanent magnets, are needed for building more efficient windmill generators, electric vehicle motors, etc. Currently, near-net shape magnets can be either made through sintering and compression molding with extensive post machining or directly through injection molding. However, injection molding has a loading volume fraction limitation of 0.65 for nylon binders. A novel method of manufacturing bonded permanent magnets with loading fraction greater than 0.65 has been demonstrated using Big Area Additive Manufacturing (BAAM) printers. As energy density is directly proportional to the square of the magnet loading fraction, magnets produced using BAAM printers require less volume and magnetic material compared to that of injection molded magnets on average. A comparative LCA shows that this difference in magnetic powder consumption nearly constitutes the difference in the environmental impact categories. Even after assuming recycled magnetic input, the BAAM magnets perform better environmentally than injection molded magnets, especially in the ozone depletion category. Since BAAM printers can accommodate even higher loading fractions, at scale, BAAM printers possibly can bring about a significant decrease in rare earth mineral consumption and environmental emissions. So furthermore, single screw extrusion enables BAAM printers to have high print speeds and allow them to be economically competitive against injection molding. Therefore, BAAM printed magnets show promise in transitioning towards the clean economy.

36 MATERIALS SCIENCE↗

NASA NTRS1972

Visual motor response of crewmen during a simulated 90 day space mission as measured by the critical task battery

In order to test various components of a regenerative life support system and to obtain data on the physiological and psychological effects of long-duration exposure to confinement in a space station atmosphere, four carefully screened young men were sealed in space station simulator for 90 days. A tracking test battery was administered during the above experiment. The battery included a clinical test (critical instability task) related to the subject's dynamic time delay, and a conventional steady tracking task, during which dynamic response (describing functions) and performance measures were obtained. Good correlation was noted between the clinical critical instability scores and more detailed tracking parameters such as dynamic time delay and gain-crossover frequency. The comprehensive data base on human operator tracking behavior obtained in this study demonstrate that sophisticated visual-motor response properties can be efficiently and reliably measured over extended periods of time.

Allen, R. W.↗

NASA NTRS1975

Design and test of a flywheel energy storage unit for spacecraft application

This paper summarizes the design and test of a development flywheel energy storage device intended for spacecraft application. The flywheel unit is the prototype for the rotating assembly portion of an Integrated Power and Attitude Control System (IPACS). The paper includes a general description of the flywheel unit; specific design characteristics for the rotor and bearings, motor-generators, and electronics; an efficiency analysis; and test results for a research unit.

Cormack, A., III↗

NASA NTRS1987

Simple, Inexpensive Servoamplifier

Circuit based on consumer-market audio-amplifier chip. Stereo audio amplifier chip, connected as servoamplifier, supplies more than 1 A to motor. Amplifier used in analog configuration to supply proportional torque to motor, simpler circuits and more efficient use of energy result when utilized in pulse-width-modulation mode. Pulse-width signals generated directly by computer software or external pulse-width-modulation generator.

Garner, H. Douglas↗

NASA NTRS2001

Baseline Testing of The EV Global E-Bike

The NASA John H. Glenn Research Center initiated baseline testing of the EV Global E-Bike as a way to reduce pollution in urban areas, reduce fossil fuel consumption and reduce Operating costs for transportation systems. The work was done Linder the Hybrid Power Management (HPM) Program, which includes the Hybrid Electric Transit Bus (HETB). The E-Bike is a state of the art, ground up, hybrid electric bicycle. Unique features of the vehicle's power system include the use of an efficient, 400 W. electric hub motor and a 7-speed derailleur system that permits operation as fully electric, fully pedal, or a combination of the two. Other innovative features, such as regenerative braking through ultracapacitor energy storage are planned. Regenerative braking recovers much of the kinetic energy of the vehicle during deceleration. The E-Bike is an inexpensive approach to advance the state of the art in hybrid technology in a practical application. The project transfers space technology to terrestrial use via nontraditional partners, and provides power system data valuable for future space applications. A description of the E-bike, the results of performance testing, and future vehicle development plans is the subject of this report. The report concludes that the E-Bike provides excellent performance, and that the implementation of ultracapacitors in the power system can provide significant performance improvements.

Eichenberg, Dennis J.↗

NASA NTRS2001

Baseline Testing of the EV Global E-Bike with Ultracapacitors

The NASA John H. Glenn Research Center initiated baseline testing of the EV Global E-Bike SX with ultracapacitors as a way to reduce pollution in urban areas, reduce fossil fuel consumption, and reduce operating costs for transportation systems. The E-Bike provides an inexpensive approach to advance the state of art in hybrid technology in a practical application. The project transfers space technology to terrestrial use via nontraditional partners, and provides power system data valuable for future space applications. The work was done under the Hybrid Power Management (HPM) Program, which includes the Hybrid Electric Transit Bus (HETB). The E-Bike is a state of the art, ground up, hybrid electrical bicycle. Unique features of the vehicle's power system include the use of an efficient, 400 W electric hub motor, and a seven-speed derailleur system that permits operation as fully electric, fully pedal, or a combination of the two. Other innovative features, such as regenerative braking through ultracapacitor energy storage, are planned. Regenerative braking recovers much of the kinetic energy of the vehicle during deceleration. A description of the E-bike, the results of performance testing, and future vehicle development plans are given in this report. The report concludes that the E-Bike provides excellent performance, and that the implementation of ultracapacitors in the power system can provide significant performance improvements.

Eichenberg, Dennis J.↗

NASA NTRS2001

Baseline Testing of the EV Global E-Bike SX

The NASA John H. Glenn Research Center initiated baseline testing of the EV Global E-Bike SX as an update of the state of the art in hybrid electric bicycles. The E-bike is seen as a way to reduce pollution in urban areas, reduce fossil fuel consumption, and reduce operating costs for transportation systems. The work was done under the Hybrid Power Management (HPM) Program, which includes the Hybrid Electric Transit Bus (HETB). The SX is a high performance, state of the art, ground up, hybrid electric bicycle. Unique features of the SX's 36 V power system include the use of an efficient, 400 W, electric hub motor, and a seven-speed derailleur system that permits operation as fully electric, fully pedal, or a combination of the two. Other innovative features, such as regenerative braking through ultracapacitor energy storage, are planned. Regenerative braking recovers much of the kinetic energy of the vehicle during deceleration. The E-Bike is an inexpensive approach to advance the state of the art in hybrid technology in a practical application. The project transfers space technology to terrestrial use via nontraditional partners, and provides power system data valuable for future space applications. A description of the SX, the results of performance testing, and future vehicle development plans are given in this report. The report concludes that the SX provides excellent performance, and that the implementation of ultracapacitors in the power system can provide significant performance improvements.

Eichenherg, Dennis J.↗

NASA NTRS2008

Developing Humanoid Robots for Real-World Environments

Humanoids are steadily improving in appearance and functionality demonstrated in controlled environments. To address the challenges of operation in the real-world, researchers have proposed the use of brain-inspired architectures for robot control, and the use of robot learning techniques that enable the robot to acquire and tune skills and behaviours. In the first part of the paper we introduce new concepts and results in these two areas. First, we present a cerebellum-inspired model that demonstrated efficiency in the sensory-motor control of anthropomorphic arms, and in gait control of dynamic walkers. Then, we present a set of new ideas related to robot learning, emphasizing the importance of developing teaching techniques that support learning. In the second part of the paper we propose the use in robotics of the iterative and incremental development methodologies, in the context of practical task-oriented applications. These methodologies promise to rapidly reach system-level integration, and to early identify system-level weaknesses to focus on. We apply this methodology in a task targeting the automated assembly of a modular structure using HOAP-2. We confirm this approach led to rapid development of a end-to-end capability, and offered guidance on which technologies to focus on for gradual improvement of a complete functional system. It is believed that providing Grand Challenge type milestones in practical task-oriented applications accelerates development. As a meaningful target in short-mid term we propose the 'IKEA Challenge', aimed at the demonstration of autonomous assembly of various pieces of furniture, from the box, following included written/drawn instructions.

Stoica, Adrian↗