Material-Efficient Permanent-Magnet Shape for Torque Pulsation Minimization in SPM Motors for Automotive Applications

• Published in: IEEE transactions on industrial electronics (1982) Vol. 61; no. 10; pp. 5779 - 5787
• Main Authors: Wenliang Zhao, Lipo, Thomas A., Byung-Il Kwon
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2014; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Analytical models; Automotive engineering; Automotive industry; Axial stress; Electrical machines; electromagnetic force; Finite element analysis; finite element analysis (FEA); finite element method (FEM); Magnetic flux; Mathematical analysis; Motors; permanent magnet (PM) machines; Permanent magnet motors; Pulsation; Rare earth metals; Rotors; Shape; sinusoidal electromotive force (EMF); Solid modeling; Torque; sinusoidal electromotive force (EMF); electromagnetic force; finite-element analysis (FEA); permanent-magnet (PM) machines; Electrical machines; finite-element method (FEM)
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2014.2301758

This paper focuses on the design and analysis of a novel material-efficient permanent-magnet (PM) shape for surface-mounted PM (SPM) motors used in automotive actuators. Most of such applications require smooth torque with minimum pulsation for an accurate position control. The proposed PM shape is designed to be sinusoidal and symmetrical in the axial direction for minimizing the amount of rare earth magnets as well as for providing balanced axial electromagnetic force, which turns out to obtain better sinusoidal electromotive force, less cogging torque, and, consequently, smooth electromagnetic torque. The contribution of the novel PM shape to motor characteristics is first estimated by 3-D finite-element method, and all of the simulation results are compared with those of SPM motors with two conventional arched PM shapes: one previously reported sinusoidal PM shape and one step skewed PM shape. Finally, some finite-element analysis results are confirmed by experimental results.