In this research, the cogging torque of a newly designed single-phase
brushless DC motor used in CD-ROM application is investigated. A finit
e element method is employed to numerically analyze the magnetic field
distribution inside the motor, in which a three-dimensional mesh is c
onstructed. The torque due to the magnetic coupling between the rotor
and stator is estimated based upon the virtual work concept. It is pro
posed in this paper that the salient pole be divided into several regi
ons in the azimathal direction. By properly choosing the radii for the
se regions; the cogging torque can be greatly reduced.