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Aaron D Anderson

Publications and source records attributed to Aaron D Anderson.

15 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2024

Preliminary Measurements of Partial Discharge Inception Voltage Degradation with Constant Temperature Aging of Magnet Wire Twisted Pairs for Electric Aircraft Motors

Electric aircraft require high reliability electric motors to meet the stringent safety standards of the aviation industry. Motor winding insulation lifetime and reliability models for electric aircraft applications are needed to enable design of high reliability and high-performance electric motors for aviation applications. Three primary stresses effect the lifetime of motor winding insulation: thermochemical, mechanical, and electrical. This paper presents preliminary experiments on twisted pairs of magnet wire targeting understanding the thermo-chemical degradation of motor winding insulation through constant temperature thermal aging. Three types of magnet wire twisted pairs where tested: polyimide insulated magnet wire, epoxy coated polyimide insulated magnet wire, and epoxy potted polyimide magnet wire. The degradation of the samples over time at temperature was tracked using partial discharge inception voltage measurements. These initial experiments were used for development of procedures and expertise in partial discharge testing and thermo-chemical aging to inform future testing. The preliminary nature of these experiments should be noted when viewing the results. Lessons learned from the experiments are documented.

Thomas Tallerico↗
NASA NTRS2023

Development and Manufacture of A Proof-of-Concept Magnetically-Geared Actuator for Use in Extremely Cold Lunar Environments

A magnetically-geared actuator is being developed for extremely cold space environments to avoid the wiring and significant efficiency penalty associated with heating grease-lubricated actuators as well as the stringent life and loading constraints imposed by dry film lubricated mechanical gears. This paper describes the lessons learned while designing, manufacturing, and assembling a proof-of-concept prototype similar to the preliminary design of the actuator.

lunar surface↗
NASA NTRS2023

Concept Design of a 5 MW Partially Superconducting Generator

This paper presents a concept design for the 5 MW generators on NASA’s SUSAN electric flight demonstrator concept vehicle. The performance targets for this machine are 25 kW/kg and 99% efficiency. The concept design is a partially superconducting machine that builds on NASA’s past work on its High Efficiency Megawatt Motor(HEMM). A partially superconducting machine design tool is used to create a preliminary concept design capable of achieving the target specifications for the SUSAN generator. Higher fidelity design and analysis is applied to the preliminary design. After high fidelity analysis the machine is predicted to achieve 22.3 kW/kg and 99.1% efficiency. Lessons learned from this concept design will be incorporated in the next iteration of the machine.

Thomas Tallerico↗
NASA NTRSDate not supplied

Design Optimization Studies of Partially Superconducting Machines based on NASA’s High Efficiency Megawatt Motor

Single aisle class electric aircraft require high power density and efficiency megawatt electric machines to be competitive with their tradition turbofan counterparts. Superconducting machines are seen as a key enabling technology for achieving the electric motor power density and efficiency needed by single aisle class electric aircraft. NASA’s High Efficiency Megawatt Motor (HEMM) is a partially superconducting machine being developed at NASA Glenn Research Center as a technology demonstration of a practical near-term superconducting machine. HEMM is being developed to meet the requirements of the generators on NASA’s STARC-ABL reference aircraft. HEMM is expected to achieve greater than 16 kW/kg electromagnetic specific power and greater than 98% efficiency at a nominal operating condition of 1.4 MW and 6800 RPM. In this paper, a design optimization algorithm for partially superconducting machines based on HEMM’s technologies is used to explore the possible performance of HEMM technology at other machine power levels and operating conditions. The design optimization algorithm is detailed in full and results for achievable geared and direct drive machine performance are presented.

Thomas F Tallerico↗
NASA NTRSDate not supplied

Concept Design a 1.4 MW Inverter for Rotor Loss Minimization in a Partially Superconducting Motor

Partially superconducting machines with cryocooler-cooled rotors are a potential near term technology that can achieve the motor performance needed by future fixed wing electric aircraft. For this type of machine, minimizing cryogenic heat load is one of the keys for enabling high machine performance. Rotor eddy current loss is often the most difficult cryogenic heat load to mitigate due to current ripple from the motor drive. This paper presents the concept design for a 20 kW/kg, 99.5 percent efficient motor drive that has sufficiently low current ripple to enable high performance partially superconducting machines by minimizing eddy current loss in the rotor. The motor drive concept design uses a resonant, interleaved, and multilevel topology to achieve these high-performance metrics with little current ripple. Rotor magnetic loss analysis using NASA’s 1.4 MW High Efficiency Megawatt Motor (HEMM) is used in the design process to down select the motor drive topology and show that the final design generates less than 5 W of magnetic loss in the rotor.

Concept design↗
NASA NTRSDate not supplied

Concept Design of a 1.4 MW Drive for Rotor Loss Minimization in a Partially Superconducting Motor

Partially superconducting machines with cryocooler-cooled rotors are a potential near-term technology that can achieve the motor performance needed by future fixed wing electric aircraft. For this type of machine, minimizing cryogenic heat load is one of the keys for enabling high machine performance. Rotor eddy current loss is often the most difficult cryogenic heat load to mitigate due to current ripple from the motor drive. This paper presents the concept design for a 20 kW/kg, 99.5% efficient motor drive that has sufficiently low current ripple to enable high performance partially superconducting machines by minimizing eddy current loss in the rotor. The motor drive concept design uses a resonant, interleaved, and multilevel topology to achieve these high-performance metrics with little current ripple. Rotor magnetic loss analysis using NASA’s 1.4 MW High Efficiency Megawatt Motor (HEMM) is used in the design process to down select the motor drive topology and show that the final design generates less than 5 W of magnetic loss in the rotor.

Cryogenic↗
NASA NTRSDate not supplied

Concept Design of a 5 MW Axial Flux Partially Superconducting Electric Machine

Single aisle class and larger electric and hybrid electric airplanes require high performance electric machines with power levels greater than 1 MW. Partially superconducting machines with superconducting rotors cooled by cryocoolers and no-cryogenic stators are one possible solution for meeting the machine performance requirements at these power levels. In this paper, a conceptual design for a double-stator single-rotor axial-flux partially superconducting machine is presented. A design tool for the topology is presented and used to generate an initial concept design. High fidelity analysis of the concept design is used to access the feasibility of the concept design to meet its target performance metrics and find areas of refinement for the next iteration of the design tool and the design.

Thomas Tallerico↗
NASA NTRSDate not supplied

Conclusions of a Cryogenic Motor Configuration Study for Aircraft Propulsion

Cryogenic electric machines are a promising technology for multi megawatt electric aircraft drivetrains. Superconducting stators that make use of low AC loss superconducting wires are considered to be a key component for these cryogenic machines. This paper shares the lessons learned from a design study that evaluated several configurations of a 5 MW cryogenic motor for this application. The lessons are drawn from a qualitative study of 16 configurations and a quantitative study of 8 down selected configurations. The quantitative study involved using analytical calculations (electromagnetic, thermofluid, mechanical, and motor sizing) to determine each configuration’s Pareto front of total efficiency and total specific power. The conclusions from a preliminary assessment of different stator conductors (superconductors and cryogenic metals) are also presented. One motor configuration is down selected for future detailed design and demonstration at the multi megawatt level.

Electrified aircraft propulsion↗
NASA NTRSDate not supplied

Motor Configuration Selection for A New Technical Challenge to Develop A 5 MW Cryogenic Motor and Drive

Due to aviation’s appreciable and growing share of humanity’s impact on our environment and estimates that CO2emissions only account for 34% of aviation’s total effective radiative forcing [1], there is a need to reach beyond climate goals that focus only on CO2emissions, such as the US Aviation Climate Action Plan’s [3] goal to reach net-zero carbon emissions by 2050.There is motivation to develop technology that pushes toward future large transport aircraft with net zero climate impact that are highly electrified (i.e., have higher power electrical propulsion system components). This paper describes a new, 6-year technical challenge to address this need by developing a 5 MW superconducting motor and cryogenic drive. Section 1 will detail the motivation for this work. Section 2 will describe the technical challenge and the selected specifications for the motor. Section 3 will present the results of a motor configuration trade study and the down selection of one configuration to develop a detailed design for. The technical challenge focuses on the design of a5 MW superconducting motor and cryogenic drive and demonstration of it at a 2+ MW scale to achieve TRL 3. Both fully superconducting (superconducting stator and rotor) and fully cryogenic (superconducting rotor and cryogenic stator) machine configurations will be explored. An emphasis will be placed on addressing the key tall poles for high power superconducting machines. Further details will be included in the full paper. The requirements and goals of the motor will be detailed. The rated speed (2,000 to 3,000 rpm) is defined to be appropriate for directly driving multi-MW fans or propellers. A range of rated speed is permitted because the motor is not designed for a specific aircraft and to provide design flexibility if AC losses in the stator winding are found to be a significant constraint (i.e., a lower speed can be selected to reduce electrical frequency). Relatively conservative requirements for efficiency (99%) and specific power (20 kW/kg) are defined, because TRL advancement and pushing toward flight readiness is emphasized over performance optimization. However, more aggressive efficiency and specific power goals are specified (99.9% and 40 kW/kg). The 3rd section will present the results of a motor configuration trade study. The study started with a qualitative assessment of sixteen motor configurations based on geometric, mechanical, thermal, and electromagnetic criteria. This assessment has been completed with three evaluators scoring all nine criteria. A configuration down select was made by prioritizing the sixteen configurations into four tiers based on each configuration’s total score and consideration of manufacturability, complexity, and support hardware (e.g., rotary vacuum seals, bearings). Configurations in priority A and B will be further evaluated through quantitative assessments, whereas those in priority C will only be further evaluated if time permits and priority D will not be further evaluated. Eight of the sixteen configurations were down selected for quantitative assessment, which will include analytical calculations and low-to moderate-fidelity finite element analysis to produce a preliminary Pareto front of efficiency versus specific power for each configuration. This assessment emphasizes the calculation of AC losses in the stator winding and an exploration of thermal management approaches to remove that heat and maintain cryogenic temperature. The final paper will include a description of each motor configuration that was considered. The quantitative assessments are underway, and an assessment of one configuration is complete for multiple stator conductor options. The remaining assessments are scheduled to be completed by late March so that the final down select to one configuration can be included in this paper.

Net Zero↗
NASA NTRSDate not supplied

Stationary Testing of a Pulse Tube Cryocooler Designed to Rotate at 6800 RPM with the Superconducting Rotor of an Electric Machine

Electrified aircraft are being developed to increase the efficiency and reduce the cost of operating subsonic transport aircraft. Achieving a substantial impact necessitates focusing on single- and twin-aisle aircraft which use propulsion systems with >20 MW ratings. For these aircraft, multi-MW superconducting electric machines are being developed due to their high specific power and high efficiency. Most of these electric machines employ superconductors on their rotor, thereby requiring cryogenic cooling of the rotating system. An attractive solution is to conductively cool the rotor using a cryocooler that rotates with the rotor. NASA has been developing a 50 K pulse tube cryocooler for its High Efficiency Megawatt Motor (HEMM) that can operate while rotating at 6,800 rpm. The design of this cryocooler and testing of its linear motor have been discussed in prior work. This presentation presents the first measurements of the complete HEMM cryocooler. The design and results of a stationary (non-rotating) test of the cryocooler are described.

electrified aircraft propulsion↗
NASA NTRSDate not supplied

Stationary Testing of a Pulse Tube Cryocooler Designed to Rotate at 6800 RPM with the Superconducting Rotor of an Electric Machine

Electrified aircraft are being developed to increase the efficiency and reduce the cost of operating subsonic transport aircraft. Achieving a substantial impact necessitates focusing on single- and twin-aisle aircraft which use propulsion systems with >20 MW ratings. For these aircraft, multi-MW superconducting electric machines are being developed due to their high specific power and high efficiency. Most of these electric machines employ superconductors on their rotor, thereby requiring cryogenic cooling of the rotating system. An attractive solution is to conductively cool the rotor using a cryocooler that rotates with the rotor. NASA has been developing a 50 K pulse tube cryocooler for its High Efficiency Megawatt Motor (HEMM) that can operate while rotating at up to 6,800 rpm. The first non-rotating tests of the fully assembled HEMM cryocooler have been completed, and initial testing has yielded a no-load temperature of 112 K. A small helium leak into the vacuum system has been identified as the major bottleneck to performance, and based on measurements with the motor turned off there is an observed vacuum-side heat leak of approximately 30 W at 115 K. Immediate next steps for testing are to locate and mitigate the apparent helium leaks into the vacuum chamber. Thus far, compressor performance and the apparent heat lift after correcting for the heat leak are on par with expectations.

Electrified Aircraft Propulsion↗
NASA NTRSDate not supplied

Lessons Learned From A Cryogenic Motor Configuration Study for Aircraft Propulsion

Cryogenic electric machines are a promising technology for multi megawatt electric aircraft drivetrains. Superconducting stators that make use of low AC loss superconducting wires are considered to be a key component for these cryogenic machines. NASA has undertaken 6-year technical challenge to address this need by designing a 5 MW superconducting motor and cryogenic drive and developing multi-MW prototypes. This poster shares the lessons learned from a completed design study that evaluated several configurations of a 5 MW cryogenic motor for this application. The lessons are drawn from a qualitative study of 16 configurations and a quantitative study of 8 down selected configurations. The quantitative study involved using a motor design code based on analytical calculations (electromagnetic, thermofluid, mechanical, and motor sizing) to determine each configuration’s Pareto front of total efficiency and total specific power. This poster builds upon preliminary results that were previously presented by (1) reporting final results based on a revised design code for each configuration, including a considerable increase in fidelity for a novel radial flux motor and (2) making a down selection of the configuration for future detailed design and demonstration and documenting the rationale for the selection.

Superconductors↗