Homopolar Machines Enabled With Electron Current Transfer Technology

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OPEN 2018
Melbourne, Florida
Project Term:
10/01/2019 - 03/31/2022

Technology Description:

Advanced Magnet Lab (AML) is developing a reliable, contact-free current transfer mechanism from a stationary to a rotating electrode to allow direct current (DC) electrical machines, motors, and generators to achieve unprecedented power and torque density. This technology, a reimagining of the first electric “homopolar” motor invented by Michael Faraday, would provide current transfer without the need for the costly sliding contacts, brushes, and liquids that have limited DC electrical engine efficiency and lifetime. AML’s contact-free current transfer would achieve 99% efficiency in DC electrical motors with 5-10 times the power and torque densities available in existing DC technologies.

Potential Impact:

An efficient, economical, high-magnetic-field, high-rpm homopolar generator/motor would revolutionize power generation, aviation and transportation industries and, due to DC power generation, would be ideally matched to DC micro grids for many applications.


Generators producing DC will significantly improve the reliability and security of a resilient electrical grid.


The transportation and electric power sectors account for nearly 75% of U.S. greenhouse gas emissions each year. More efficient and economical motors will encourage wider use of EVs and wind power, significantly reducing emissions.


A homopolar machine using superconductivity has the potential to achieve greater than 30kW/kg, which represents a significant leap forward in electromagnetic component weight reduction. For example, one to two thousand dollars per pound of weight saved are reasonable values for commercial aircraft.


ARPA-E Program Director:
Dr. David Tew
Project Contact:
Dr. Philippe Masson
Press and General Inquiries Email:
Project Contact Email:


Eagle Power Technologies
North Carolina State University

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