Cogging Force Reduction of a Stationary Discontinuous Armature PM-LSM by Magnet Segmentation

Recently, permanent magnet type linear synchronous motors have been used as a driving source of transportation systems, to satisfy requirements such as speeding up of transportation systems and also to simplify maintenance. The authors´ laboratory has proposed a stationary discontinuous armature PM-LSM in which the armature is engaged only when accelerated and decelerated operation is necessary, in order to resolve the problem of higher costs, when PM-LSM is used with long-distance transportation systems in factories. However, the stationary discontinuous armature PM-LSM contains the outlet edges which always exist as a result of the discontinuous arrangement of the armature. These edges become a problem, because the cogging force that they exert influences the controllability of the motor. This paper presents the results of an experimental examination and three-dimensional numerical analysis by the finite element method of the cogging force exerted by the outlet edge. Moreover, we modified the permanent magnet on the mover to decrease the cogging force at the outlet edge, and the results are examined using three-dimensional numerical analysis by the finite element method.