Fringing in tubular permanent-magnet machines: Part I. Magnetic field distribution, flux linkage, and thrust force

This paper extends an analysis developed for tubular permanent-magnet machines to account for the effect of fringing associated with the finite length of the ferromagnetic armature core. The magnetic field distribution, established by using an analytical technique formulated in the cylindrical coordinate system, provides an accurate means of evaluating the effect of the fringing flux on the thrust force and the back-electromotive force. Finite-element calculations confirm the analytically derived results. In Part II of the paper, the analysis is used to predict the cogging force that results from end effects and to facilitate minimization of the force.

[1]  Gu Qishan,et al.  Effect of Slotting in Pm Electric Machines , 1985 .

[2]  G. Xiong,et al.  Analysis of fields and forces in a permanent magnet linear synchronous machine based on the concept of magnetic charge , 1989 .

[3]  R. Akmese,et al.  Dynamic performance of a brushless DC tubular drive system , 1989, International Magnetics Conference.

[4]  A. Basak,et al.  Computation of magnetic field in DC brushless linear motors built with NdFeB magnets , 1990 .

[5]  H. C. Lai,et al.  Optimum design of brushless tubular linear machines , 1990 .

[6]  J. F. Eastham,et al.  Novel synchronous machines: linear and disc , 1990 .

[7]  A. Vourdas,et al.  Magnetic field and eddy current losses in linear and rotating permanent magnet machines with a large number of poles , 1991 .

[8]  T. Mizuno,et al.  Magnetic circuit analysis of a linear synchronous motor with permanent magnets , 1992 .

[9]  M. E. Williams,et al.  Design and analysis framework for linear permanent magnet machines , 1994, Proceedings of 1994 IEEE Industry Applications Society Annual Meeting.

[10]  D. Howe,et al.  Design optimisation of moving-magnet actuators for reciprocating electro-mechanical systems , 1995 .

[11]  David L. Trumper,et al.  Analysis and implementation of a tubular motor with Halbach magnet array , 1996, IAS '96. Conference Record of the 1996 IEEE Industry Applications Conference Thirty-First IAS Annual Meeting.

[12]  Ion Boldea,et al.  Linear electric actuators and generators , 1997, 1997 IEEE International Electric Machines and Drives Conference Record.

[13]  I. Boldea,et al.  Linear Electric Actuators and Generators: Linear Electric Actuators and Generators , 1997 .

[14]  Jiabin Wang,et al.  A general framework for the analysis and design of tubular linear permanent magnet machines , 1999 .

[15]  Weili Yan,et al.  3D multifields FEM computation of transverse flux induction heating for moving-strips , 1999 .

[16]  D. Howe,et al.  Fringing in tubular permanent-magnet Machines: part II. Cogging force and its minimization , 2003 .