Analysis of axially magnetised, iron-cored, tubular permanent magnet machines

An analysis of tubular permanent magnet machines equipped with axially magnetised magnets and a slotted armature is presented. The magnetic field distribution due to armature reaction is established analytically in the cylindrical co-ordinate system, and the results are verified by finite element calculations. The analytical solution allows the prediction of the machine inductance and reluctance force in closed forms, and facilitates the design optimisation and the evaluation of any possible partial, irreversible demagnetisation of the magnets.