Effectiveness of active cooling on torque performance for prosthestic applications
Name
1013189207-MIT.pdf
Description
Full printable version
Size
5.99 MB
Format
Adobe PDF
Checksum (MD5)
83666e6cf20202e27c2edf3dcf688f13
Author(s)
Chen, Ava E
Advisor(s)
Hugh M. Herr.
Date Issued
2017
Publisher
Massachusetts Institute of Technology
Abstract
Motors used to actuate powered prostheses generally under-utilize their torque capacity due to thermal limitations of the windings. This thesis investigates the effectiveness of increasing the rate of heat transfer away from the windings in order to enable running motors at higher currents than their rated maximum levels, thus raising this torque saturation limit. Simulation models and physical prototypes based on the RCTiger 100KV U8 brushless outrunner motor were built to observe the temperature of the windings as constant current was applied to the motor. The addition of a fan-based active cooling system allowed the motor to run at 142% of its maximum continuous current rating for up to 56 seconds before winding temperatures exceeded 550 C, and limited temperature increase in simulation to 26' above ambient temperature when the full 35A stall current was applied for one second. Although the simplified circuit model was not able to fully capture nonlinear thermal behavior of the motor, simulations were able to predict approximate heating time constants and time duration before windings reached threshold temperature for current ranges 5- 15A. Experimental and simulation results support the hypothesis that active cooling enables motors to run at their full torque potential for short periods of time, which holds promise for the use of cooling mechanisms in prosthetic applications.
Description
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 53-54).
Subjects
Mechanical Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Terms of Use
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