Session: 17-01-01: Research Posters

Paper Number: 151641

151641 - Thermal Management of Axial Flux Permanent Magnet Motors in Next-Generation Aircraft 

Resistive heating in Axial Flux Permanent Magnet (AFPM) motor stator coils is a significant limiting factor in motor power output. Contributing to the Department of Energy’s Aviation-class Synergistically Cooled Electric-motors with iNtegrated Drives (ASCEND) program, the goal of this project is to develop a highly efficient AFPM motor thermal management system (TMS) to optimize AFPM motor power density for applications in next-generation aircraft. Our approach proposes a TMS that facilitates heat transfer through heatsinks (pumped with 85% ethylene glycol-15% water mixture coolant) interfaced with an AFPM motor’s stator coils. A thermal energy storage (TES) component provides a buffer, or thermal capacitance, for the TMS, enabling the design of a power dense motor optimized for the specific flight profile, however it was not tested in the experiments reported here. For the TMS test design, a copper block was machined into the shape of three conjoined windings to serve as a “simulated windings” structure within the setup, and cartridge heaters were inserted into these copper block windings to emulate the heating behavior typical of actual AFPM motor stator windings during flight. The thermal energy dissipated from these simulated windings served as an input to the TMS heatsinks. The simulated windings were thermally connected to three separate heatsinks with a graphene-based thermal interface material (TIM), and these heatsinks were clamped onto the simulated windings to ensure uniform thermal contact between the heat sinks and windings. For temperature and pressure measurements of the TMS, T‑type thermocouples were inserted into the simulated windings to record winding temperature. T‑type thermocouples were also used to measure and record the inlet and outlet coolant temperatures for each heatsink, and pressure transducers were used to measure the coolant pressure drop across a single heatsink. To verify uniform flow, this pressure drop measurement was performed on two of three heatsinks while ensuring the same simulated winding temperatures and heat removal rates for the heatsinks across two different experiments, however only a single heatsink pressure drop was measurable in an experiment. In this poster presentation, we present data for experiments conducted at steady state heat input (i.e., 50, 100, 150, 200, 300, 450, 600 W) for a single coolant flow rate and varying coolant flow rates (i.e., 2, 4, 6 LPM) at 300 W heat input for bare windings (i.e., not electrically insulated), and steady state heat input (i.e., 50, 100, 150 , 200,  220 W) for a constant flow rate with Kapton-wrapped windings (i.e., electrically insulated with traditional dielectric materials) were tested. These steady state heat input tests experimentally simulated a cruise profile for an aircraft during flight. We expectantly find that Kapton-wrapped windings have a higher temperature than bare windings at equivalent steady states while maintaining statistically equal heat transfer rates. Additionally, increasing the coolant flow at 300 W steady state caused a decreasing average winding temperature and increasing pressure difference. We conclude that a new generation of thermally conductive dielectric coatings are required to enable high power density electric motors for electric aviation applications.

Presenting Author: Harry Lance Hendrix College

Presenting Author Biography: I am an undergraduate, junior physics major and applied mathematics minor at Hendrix College in Conway, Arkansas. During the 2024 Undergraduate Summer Research Experience (USRG) at Texas A&M University, I worked in Dr. Dion Antao’s Thermal Engineering Group (TEG) at Texas A&M University on the development of a highly efficient Axial Flux Permanent Magnet (AFPM) motor thermal management system (TMS) to optimize AFPM motor power density for applications in next-generation aircraft, contributing to the Department of Energy’s Aviation-class Synergistically Cooled Electric-motors with iNtegrated Drives (ASCEND) program. I am interested in attending graduate school for thermal engineering.

Authors:

Harry Lance Hendrix College
Shiyu Zhang Texas A&M University
Dion Antao Texas A&M University