2006 Volume 126 Issue 12 Pages 1706-1711
This paper discusses the effect of manufacturing deterioration and permanent magnet conditions on cogging torque and iron loss in 12-pole small motors using 9-slot cores (20mm outer dia.). Manufacturing stress and strain increase 12n-th order cogging torques and iron loss, and smaller-clearance punching and larger-clearance clinching reduces iron loss althouogh they hardly affect cogging torque. The 9n-th order cogging torques are influenced a little by stress-relief annealing. The magnetization conditions of permanent magnet influences not only iron loss, but also cogging torque, which may be proportional to the square of magnet magnetization. However, cogging torques are hard to be induced at lower magnet magnetization.