Magnet shaping for minimal magnet volume in machines

An expression for the no-load flux linkage in permanent-magnet (PM) machines is derived. From this expression, a method, is proposed to increase the no-load flux linkage generated in a stator winding per volume of PM material. The method is suitable for machines with short pole pitch and is applied to a transverse-flux machine with single-sided surface-mounted PM. The result is an increase of 37% of the no-load flux linkage per volume of PM, compared with the case of rectangular PM covering 100% of the pole pitch. An increase of 15% is also obtained, if compared with the common practice of using PM covering 80% of the pole pitch.