Disc-type PM machine for the electromagnetic conversion/suspension of a flywheel system

The paper presents the design and the electromagnetic analysis of a disc-type permanent magnet machine with transverse flux homopolar (TFHM) magnetic configuration, suitable for the energy conversion in a high speed flywheel energy storage system (FESS). By means of an effective design procedure dealing with integrated analytical and 2D finite element analyses (FEAs), a modular TFHM geometry has been assessed, fulfilling the specifications of a typical energy intensive stationary FESS. Further simplified but more accurate 3D FEAs are used to enable a performance improvement as for the force and the torque ripple by a proper combination of stator modules and saliencies number.