Reduction of the Cogging Force at the Outlet Edge of a Stationary Discontinuous Primary Linear Synchronous Motor

Recently, permanent-magnet-type linear synchronous motors (PM-LSMs) 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 primary PM-LSM in which the primary 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 primary PM-LSM contains the outlet edges which always exist as a result of the discontinuous arrangement of the primary. 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 (3-D) numerical analysis by the finite-element method (FEM) of the cogging force exerted by the outlet edge. Moreover, we deformed the shape of the primary to decrease the cogging force at the outlet edge, and the results are examined using 3-D numerical analysis by the FEM