Analytical Calculation and Experimental Verification of Cogging Torque and Optimal Point in Permanent Magnet Synchronous Motors

• Published in: IEEE transactions on magnetics Vol. 53; no. 6; pp. 1 - 4
• Main Authors: Shin, Kyung-Hun, Park, Hyung-Il, Cho, Han-Wook, Choi, Jang-Young
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2017; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Air gaps; Analytical method; Boundary conditions; Cogging; cogging torque; Design analysis; Design engineering; Design optimization; Finite element method; Forging; Fourier analysis; Iron; magnetic field; Magnetism; Motors; Nonlinearity; optimization; Rotors; Stator windings; Synchronous machines; Synchronous motors; Torque
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2017.2667643

In this paper, an exact analytical solution based on Fourier analysis is proposed to compute the cogging torque in a surface-mounted permanent magnet synchronous machine. The analytical solutions are derived by solving the field-governing equations in each simple and regular subdomain, i.e., permanent magnet (PM), air, slot opening, and slot, and then by applying the boundary conditions to the interfaces between these subdomains. Based on these solutions, the cogging torque is also determined analytically. In order to verify the analytical results of the proposed method, an experimental system was implemented on a servomotor and a torque sensor. All analytical results were extensively validated using nonlinear 2-D finite-element analysis and experimental results. Using the proposed method, we investigated the influence on the cogging torque, according to the machine parameters. Therefore, the proposed method should be very useful in the initial design and cogging torque optimization of PM machines.