Factors affecting eddy current losses of segmented Nd-Fe-B sintered magnets without insulation in large PM motors

In large permanent magnet motors, the permanent magnet in the motor is segmented into parts in order to reduce the eddy current loss in permanent magnet. It is reported that the insulation between sintered Nd-Fe-B magnets is possible only by contacting the segmented permanent magnets without insulation. But the mechanism for such a phenomenon has not been clear. We have already reported that the analysis considering the resistance of the contact part is possible by defining the contact resistance coefficient K. In this paper, the effects of number of segments of magnet, exciting frequency and contact resistance between magnets on the eddy current loss of the magnet are investigated.