Varying magnetization orientation for permanent-magnet volume reduction in machines

We present an enhanced version of a method to minimize the amount of permanent-magnet (PM) material required to create a certain flux linkage in the stator winding of a PM machine. The enhanced version obtains the distribution of the factor δ inside the PM; δ identifies the areas inside the PM volume where the orientation of magnetization may be modified, so as to further increase the amount of no-load flux linkage generated by the PM per cubic meter of PM material. The paper shows how this method can be used with increased benefits in machines with small pole pitches. The case of a transverse-flux permanent-magnet (TFPM) machine with a pole pitch of 1 cm is analyzed. The resulting PM design shows an improvement of 48% of the amount of flux linkage created per volume of PM material, for the same air-gap thickness and magnet thickness.