Impulse magnetization strategies for an external rotor brushless DC motor equipped with a multipole NdFeB magnet

There are a number of stages during the manufacture of a brushless DC motor at which it may be possible to impulse magnetize the permanent magnets, namely: (i) component magnetization, of the magnet poles separately or of the complete multipole magnet; (ii) sub-assembly magnetization, of the assembled multipole rotor; and (iii) post-assembly magnetization, of the fully assembled motor. Here, the authors describe how, in order to aid the design optimisation of multipole magnetization systems, and eliminate fixture design by trial-and-error, an integrated CAD methodology has been developed. It involves a number of phases, the level of sophistication of the design/analysis tools increasing as the feasible design space contracts