Analysis of rotating resistance of a magnet base.

Abstract

This paper deals with the analyzing results of rotating resistance of a magnet base from both the sides of theory and experiment. The value of rotating resistance of the magnet base has been decided mainly by materials of the permanent magnet in the magnet base through the experiences, but the suitable explanation on the rotating resistance has not yet been established.In this paper, the following points are discussed.(1) An actual permanent magnet within a magnet base is rotated on the yoke in eccentric contact condition. Here, it was assumed that the permanent magnet was rotated on the yoke in non-contact condition with gaps from 0.1 to 0.3mm. The theoretical expression of the rotating resistance was derived by the permeance analysis method.(2) The calculated values of rotating resistance by the theoretical expression with ferrite and alnico magnets are almost consistent with the measured values.(3) It is clarified that the rotating resistance of the magnet base with the ferrite magnet is about 50% less than that with the alnico magnet from a viewpoin of the theory as well as experiment. It can be explained that the values of rotating resistance mainly depend upon the recoil permeability of permanent magnets.