Halbach magnetized permanents magnets brushless machines offer several attractive features. For example, the airgap field distribution which results from the Halbach magnetization is inherently sinusoidal, which makes for negligible cogging torque and an essentially sinusoidal emf waveform, without recourse to conventional design features such as skewing of the stator/rotor, optimization of the magnet pole-arc, etc. For more information, you can read this article:

Z. Q. Zhu and D. Howe, “Halbach permanent magnet machines and applications: a review,” IEE Proc. - Electr. Power Appl., vol. 148, no. 4, p. 299, 2001.

Best regards,

Florian Sanchez

Thanks for the inputs Mr Florian Sanchez

A disadvantage is that assembly of the array is under repulsion and can be difficult; a large amount of potential energy can be stored; the arrays can explode if improperly contained.

Cheers,

Doug