Session: 20-17-01: Rising Stars of Mechanical Engineering

Paper Number: 172167

Magnetically Integrated Electric Drive With Rare-Earth-Free Motors 

Electric motors and generators play a crucial role in diverse industries, facilitating the widespread adoption of electric vehicles, enhancing industrial productivity, and harnessing renewable energy sources. Nonetheless, existing technologies heavily depend on costly rare-earth permanent magnets, which present significant obstacles to achieving sustainability objectives and promoting electrification efforts. The demand for rare-earth permanent magnets, such as neodymium iron boron (NdFeB), is expected to surge more than 20 times to fulfill sustainable energy and transportation goals by 2050. The projected demand for rare-earth magnets in offshore wind turbine and electric vehicle applications will reach 36.3% (273.7 kt) and 35.3% (266 kt), respectively, which is more than 70% of the total demand. Therefore, identifying motor drives that are free from rare-earth elements yet maintain high-performance and efficiency is a significant area of research. 

This NSF CAREER project aims to develop a next-generation magnetically integrated electric drive system utilizing a topologically optimized, magnet-free, and brushless wound-field flux-switching (WFFS) motor, thereby eliminating the need for expensive, supply-constrained, and environmentally problematic rare-earth permanent magnets. The research is driven by three tightly integrated objectives: (1) to optimize the WFFS motor’s magnetic topology by eliminating parasitic flux paths and maximizing magnetic circuit efficiency, (2) to co-design the motor and power electronics for high torque density, thermal robustness, and compact packaging, and (3) to accurately model and quantify system-level losses—both electrical and thermal—to inform the development of real-time, loss-minimizing control strategies for high-performance operation.

This work addresses a critical technological gap in the electrification ecosystem by providing a rare-earth-free electric drive platform that can meet or exceed the performance of conventional permanent magnet-based drives, without the associated material and cost constraints. The broader impacts of this research extend to multiple high-impact sectors including electric vehicles (EVs), renewable energy systems, more electric aircraft (MEA), and automated industrial processes, where reliable, efficient, and compact electric drives are essential for achieving next-generation performance and sustainability benchmarks. In particular, the proposed WFFS motor is well suited to demanding operating environments that require brushless operation, high reliability, and integrated control features.

In addition to advancing electric machine design and power electronics integration, the project responds directly to environmental and geopolitical challenges posed by the increasing demand for rare-earth materials. By eliminating rare-earth dependency, the proposed solution improves long-term supply chain resilience and aligns with global efforts to decarbonize transportation and energy infrastructure. Furthermore, the project contributes to the growing demand for high-power-density, thermally optimized electric drives capable of operating under tight packaging constraints and extended duty cycles.

Beyond its technical contributions, this project also serves as a platform for educational innovation, training graduate and undergraduate students in multidisciplinary topics at the intersection of electromagnetics, thermal science, power electronics, and control systems. The tools, models, and hardware developed in this research will be openly disseminated to foster further academic and industrial research. Ultimately, this project will significantly advance the field of sustainable electric drive technologies, support the global transition to clean energy systems, and position the U.S. at the forefront of rare-earth-free electric propulsion innovation.

Presenting Author: Woongkul Lee Purdue University

Presenting Author Biography: Woongkul Lee received the M.S. and Ph.D. degrees from the University of Wisconsin-Madison, WI, USA, in 2016 and 2019 respectively both in electrical engineering. He received the B.S. degree from Yonsei University, Seoul, South Korea, in 2013. He was a postdoctoral research associate with the Wisconsin Electric Machines and Power Electronics Consortium (WEMPEC), University of Wisconsin-Madison from 2019 to 2020. In 2024, he joined Elmore Family School of Electrical and Computer Engineering at Purdue University as an assistant professor. Prior to that, he was an assistant professor at Michigan State University. His research interests include high-performance motor drive, power electronics, electric machines, and distributed energy resources. His commitment to advancing energy efficiency and sustainability was recognized in 2024 with the prestigious NSF CAREER award and ARPA-E IGNIITE Early Career Award.

Authors:

Woongkul Lee Purdue University