Design of bridgeless IPMSM to reduce mass of applied permanent magnets

• Published in: International journal of precision engineering and manufacturing Vol. 15; no. 7; pp. 1467 - 1472
• Main Authors: Park, Jin-Young, Lee, Jae-Wook, Oh, Joo-Young, Cho, Jung-Woo, Jeong, Myeong-Sik, Lee, Sang-Kon, Bae, Jae-Nam, Kim, Hyun-Deok
• Format: Journal Article
• Language: English
• Published: Springer Korean Society for Precision Engineering 01.07.2014
• Subjects: Engineering; Industrial and Production Engineering; Materials Science; Power density; HEV; EV; IPMSM; Rare-earth permanent magnet; Traction motor
• ISSN: 2234-7593; 2005-4602
• DOI: 10.1007/s12541-014-0492-9

Interior permanent magnet synchronous motors (IPMSMs) are frequently used in industrial applications because their efficiency and power density are both very high. The IPMSM also makes a very good choice for an electric vehicle or hybrid electric vehicle, because the range of operating speeds is wide enough for use in traction applications. Recently, however, as a result of concerns about there being insufficient supplies of rare earth permanent magnets as well as atmospheric pollution caused by the exhaust gases of automobiles, a need has arisen for motor technologies that require fewer magnets and which can offer a higher level of efficiency. In this paper, we propose a bridgeless IPMSM as a means of reducing the number of permanent magnets used in a motor while simultaneously increasing the power density. The bridge structure, which supports the centrifugal forces generated in a motor’s permanent magnets as the rotor core rotates, was eliminated. To provide support for the separated pole-pieces and permanent magnets, new supporting structures are proposed. As a result, although the air gap torque of the bridgeless IPMSM is almost the same as that of the conventional design, the mass of the permanent magnets can be reduced by 10%.