Performance analysis of a novel magnetic-geared tubular linear permanent magnet machine

This paper presents a novel tubular linear permanent magnet machine for direct-drive applications, in which a magnetic gear is integrated with a tubular linear machine, aiming to improve the thrust force density and enhance the machine efficiency. The operating principle of the proposed machine is introduced and the machine design with improved thrust force density is presented and discussed. By using circuit-field-motion coupled time-stepping axisymmetric finite element method (FEM), the steady-state as well as transient performances of the machine are simulated. The FEM computation results are consistent with those obtained theoretically, hence verifying the validity of the machine design.