Design of an Ironless Double-Rotor Radial Flux Permanent Magnet machine

This paper presents initial work and prototyping of an Ironless Double-Rotor Radial Flux Permanent Magnet (IDRFPM) machine. The design stems from high-efficiency generators intended for wind power but will be used in motor operation to propel a small vehicle for the Shell Eco Marathon where efficiency is of paramount importance. The design intends to augment performance by increasing torque density, replacing heavy steel yoke components with non-magnetic composites and tangentially magnetized PM´s to form a quasi-Halbach arrangement. This text will explain basic performance characteristics of the machine and review the design methodology and development of the topology. A comparison is made of the torque densities of the new topology and its predecessor. The analysis concludes that, while initial results indicate favourable torque density, testing of a prototype and development of a thermal model will be necessary to directly compare the IDRFPM machine with competitors.