Toward Less Rare-Earth Permanent Magnet in Electric Machines: A Review

• Published in: IEEE transactions on magnetics Vol. 57; no. 9; pp. 1 - 19
• Main Authors: Poudel, Bikrant, Amiri, Ebrahim, Rastgoufard, Parviz, Mirafzal, Behrooz
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Demagnetization; Electric machines; Electric motors; Energy conversion; Ferrites; Hybrid structures; Induction motors; Magnetic flux; Magnetic poles; magnetic volume; Magnetism; Neodymium; Permanent magnets; Perpendicular magnetic anisotropy; Rare earth elements; rare-earth (RE) material; Reluctance motors; review; Samarium; State-of-the-art reviews; Topology
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2021.3095615

Many electric traction drive systems (ETDSs) are driven by electric motors primarily composed of high-energy rare-earth (RE) permanent magnets (PMs), such as neodymium-iron-boron (NdFeB) and samarium-cobalt (SmCo). Given the high cost of RE materials, there is a great interest among various industry sectors in searching for breakthrough technologies that reduce the consumption of high-energy RE magnets in their electromechanical energy conversion systems. The reduction of the magnetic volume is typically realized either by replacing a portion of the high-energy RE magnet with the low-energy ferrite magnet (knows as hybrid structure) or by modifying the magnetic arrangement of the machine itself, where a portion of the physical RE magnets is removed and replaced by induced magnets (known as consequent-magnetic pole structure). For this purpose, this article presents a review of the current state-of-the-art motor typologies with less-RE PMs and their key design challenges, followed up by a series of recommended guidelines to overcome related design challenges.