Design and field analysis of a magnetic gear integrated tubular linear permanent magnet machine

This paper proposes a novel linear permanent magnet machine for direct drive applications in which a magnetic gear is ingeniously integrated with a tubular linear machine, aiming at improving the thrust force density and enhancing the machine efficiency. The operating principle of the proposed machine is introduced. An optimal design with reduced cogging torque, improved thrust force density, and enhanced power factor is presented and discussed. By using circuit-field-motion coupled time-stepping finite element method (FEM), the steady-state as well as transient performances of the machine are simulated. The FEM computation results are consistent with theoretical analysis, hence verifying the validity of the machine design.