Homopolar variable reluctance machine incorporating an axial field coil

Switched reluctance drives have been shown to benefit from DC flux assistance from a coil arrangement that is mutually coupled to all its phase windings. This paper proposes an alternative way of providing this additional DC flux through the use of a toroidal, axially orientated coil. A reluctance machine is constructed and tested in which the stator comprises two stacks separated by a coil to give axial magnetic flux. This construction is similar to a homopolar inductor alternator. The paper describes and develops the complex magnetic structure of the machine and describes initial test results. The ideal angular orientation between the two stator stacks is presented.