Calculating the external magnetic field from permanent magnets in permanent-magnet motors-an alternative method

• Published in: IEEE transactions on magnetics Vol. 40; no. 5; pp. 3278 - 3285
• Main Authors: Selvaggi, J.P., Salon, S., O-Mun Kwon, Chari, M.V.K.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.09.2004; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Charge simulation; Computational modeling; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cylindrical coordinates; Distributed computing; Equivalence; Exact sciences and technology; Fourier series; Geometry; History; Magnetic fields; Magnetic properties and materials; Magnetism; Mathematical models; Motors; Permanent magnet motors; Permanent magnets; Physics; Scalars; Solid modeling; Toroidal magnetic fields; Charge simulation; toroidal function; charge surface; potential surface; Q functions; Magnetic materials; Legendre function
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2004.831653

We present an alternative method for calculating the magnetic field from a set of permanent magnets in a permanent-magnet motor. The method uses a cylindrical coordinate system to model the geometry of the structure enclosing the magnets. A Fourier series expansion yields an alternative to the more familiar multipole expansion given in spherical coordinates. The expansion is developed by using Green's function in cylindrical coordinates. A technique called charge simulation allows computation of an equivalent point charge distribution. Finally, Coulomb's law is applied to express the magnetic scalar potential in a mathematically tractable form.