Fault-tolerant primary-permanent magnet linear machine employing modular secondary

This paper proposes and analyzes a new three-phase primary-permanent magnet linear machine which is suitable for long stroke applications such as rail transits. The key of this new topology is to adopt modular secondary to improve machine performance and reduce machine size. The electromagnetic performances of the newly designed machine are analyzed, including the flux, back-EMF, inductance, fault tolerance, thrust force as well as flux density. The finite-element analysis (FEA) results show that the proposed machine not only retains the merits of primary-PM linear machines, but also offers symmetric back-EMF, high flux density, high thrust force and high fault-tolerant capability. Especially, the proposed 12/7-pole topology incorporates the merit of decreasing the height of the secondary, thereby reducing the whole height of the machine, which has a close relation with subway construction cost.