| 摘要 |
A brushless DC motor having a number of armature poles (38-52) which is neither a multiple nor a submultiple of the number of field poles (12-22), thereby providing a relatively high cogging-ripple frequency. The field pole faces, which are generally arcuate in cross-section, have centrally disposed depressions (12d-22d). These depressions reduce the torque exerted by the armature when pole boundaries of the armature pass by the centers of the field poles. This reduces both torque ripple and cogging ripple and it doubles the frequency of torque ripple. |
