A two-dimensional analytical model is proposed for slotless brushless
machines with arc-shaped spoke permanent magnets assisted by hub magnets
to calculate the magnetic field distribution due to magnets and armature
reaction, the electromagnetic torque, and back electromotive force. To
verify the model, the analytical results of the field distribution,
electromagnetic torque and back electromotive force have been compared
with those achieved from finite element method. Moreover, this model is
used as an equivalent analytical model for a cubic spoke motor, and it
is shown that the proposed equivalent sub domain model satisfactorily
estimates the electromagnetic quantities.