An improved axially magnetised tubular permanent magnet machine topology

The paper describes an improved design for an axially magnetised tubular permanent magnet machine. Compared with a conventional axially magnetised tubular machine, it has a higher specific force capability and requires less permanent magnet material. The magnetic field distribution is established analytically in the cylindrical co-ordinate system, and the results are validated by finite element analyses. The analytical field solution allows the analytical prediction of the thrust force and back-EMF in closed forms, which, in turn, facilitates the characterisation of a machine, and provides a basis for design optimisation and system dynamic modelling.