, for sure friend
The single primary difference between a Halbach Array
(HA) and traditional motor magnet arrangements is that the HA consists of at least two magnets to create a single pole, and minimum four magnets to create the N-S pairing. Excellent short-subject here:http://en.wikipedia.org/wiki/Halbach_array
The primary value is that the magnetic field & associated flux density are flipped to one side as oppose to both sides experiencing forces. The field is not precisely doubled, though in laymanÃ¢â‚¬â„¢s terms it is effectively so, and this lends itself to significantly enhanced characteristics desirable in both magnetic levitation and drive systems where space is at a premium.
The HA also eliminates the Ã¢â‚¬Å“Flux Ring
Ã¢â‚¬Â associated with non-HA AF orientations. Without the Flux Ring, the magnetic circuit would leak from the system ~ and actually based on the FEMM studies it is better to say Ã¢â‚¬Å“flood
Ã¢â‚¬Â, for without the ring there is nothing but air to constrain the field. The HA, by implied physical arrangement, redirects the lossy field with measurably superior effectiveness over the flux ring.
With linear or even radial systems HA is pretty economical, however in the axial arrangement the magnets need to be wedge-shaped and in physical contact. It is this wedge-shape that is expensive for custom designs. It is definitely a huge tooling cost as Thud
had pointed out earlier. The special feat of correct engineering requires that the design of the object fit within reasonable production, timely manner, and cost-effective. The raw materials must also be readily available.
When I began this study I initially had costs for a 2-rotor/1-stator down to around $600 for magnets ~ and I thought that was livable for a one-off prototype. Now I am looking at $2000 per wheel and itÃ¢â‚¬â„¢s no longer a viable option. Small thread on the price shift
. I think we can do better.
Using the same philosophy as we have with the HobbyKing LiPos for building battery packs, we leverage the mass-production units to construct a reasonable AF solution. LetÃ¢â‚¬â„¢s grab some common inexpensive stock and make do with it! Note that the significant part of this challenge is that each magnet supplier is slightly differentiated on height, width, length, strength, and heat-tolerance
: It takes a willingness to compromise on the ideal
, and a spreadsheet to keep track of the assets.
I am going to pick one supplier, roll the numbers, and see where and how we can bake this AF cake into an equally tasty HA-alternative. Then weÃ¢â‚¬â„¢ll pick another supplier and do the same. As we canvas and survey the possibilities, our additive comprehension of the indefinite envelope for opportunity will resolve as tangible, and once there we should be able to articulate a wide assortment of solutions.
Make sense? KF