No Commercial Halbach Array Motors?

[mattchematt]

Help me out here.

Why are there NO commercially available Halbach Array motors to be found, anywhere?

Is there a good reason?

Thanks!

 

[fechter]

I assume it must be due to cost. Iron is a lot cheaper than magnets. Production cost would be higher too.

 

[Toorbough ULL-Zeveigh]

the cost/benefit for most apps simply isn't worth it.
lotta pain for little gain, classic case of diminishing returns.

The efficiency of a CM with surface PM is 97.5% whereas the efficiency with a halbach array is 98.2% respectively

plus that increased efficiency only occurs at lightly loaded low torque levels.
under high torque requirements in order to create the same magnetic field strength as an iron backed motor an ironless motor has to compensate by consuming high current levels.
copper losses become so large efficiency goes in the tank below that of a non-halbach.


normal electric motors are already up there with pretty good efficiency.
there's not a whole lot of room for improvement.
it's only for those that really need that small gain & are willing to pay for it.
i.e. niche market like solar cars & even those opt for the cheaper non-halbach.






so far these are the only halbach motors that are anywhere close to commercial production.
http://www.endless-sphere.com/forums/viewtopic.php?f=30&t=14260
http://amcrc.com.au/engineering-and-csiro

 

[Microbatman]

Launchpoint had developed one but they are going after big quantitiy buyers.

http://endless-sphere.com/forums/viewtopic.php?f=30&t=14260

 

[chicagoDan]

They are not advertise as Halbach. Torqueedo does make them in large scale for their outboards. It is called branding. Tesla (the car) might have one etc. There is not enough money in selling small quantities. If you really got to have one I would go with Torqueedo or have a motor repair shop make you one. I would have second thoughts about buying from engineering houses (that sell just a few) unless I knew the supply chain and the people (costly).

 

[Jeremy Harris]

They are not advertise as Halbach. Torqueedo does make them in large scale for their outboards. It is called branding. Tesla (the car) might have one etc. There is not enough money in selling small quantities. If you really got to have one I would go with Torqueedo or have a motor repair shop make you one. I would have second thoughts about buying from engineering houses (that sell just a few) unless I knew the supply chain and the people (costly).

Torqeedo use ordinary outrunners with conventional neo magnets in similar configurations to the motors we are familiar with.

The Tesla uses an AC induction motor with variable frequency drive - it's not a PM motor.

To the best of my knowledge the only PM motors around that use Halbach arrays are the ones being sold at high prices for specialist purposes, like the CSIRO motor.

 

[Miles]

They are not advertise as Halbach. Torqueedo does make them in large scale for their outboards. It is called branding. Tesla (the car) might have one etc. There is not enough money in selling small quantities. If you really got to have one I would go with Torqueedo or have a motor repair shop make you one. I would have second thoughts about buying from engineering houses (that sell just a few) unless I knew the supply chain and the people (costly).

What a load of generated bollocks...... Waiting for the spam link.....

 

[Jeremy Harris]

A little more vigorous than my rather tame rebuttal, Miles................. :wink:

 

[Miles]

I've got no tolerance for this stuff anymore.......

 

[Kingfish]

I believe the patent holder for Halbach Array is the United States Government by way of contract between the United State Department of Energy and the University of California/Lawrence Livermore National Laboratory. I cannot find a patent date earlier than 1995 (patent #5,705,902), although I'm sure one must exist.

Regardless, any industry seeking to use the “device” is bound to strict usage for research or military needs first, and commercially second.

I’m fairly certain that any private individual could make a motor for their own investigation without penalty, though I bet if one tried to go into production there would in short order be a knock at the door by the Men in Black.

For myself exploring AF, I thought I could produce a motor of better efficiency without restoring to Halbach; the simulations indicated higher flux density and reduced cost by employing back iron. Think of it this way:

• Halbach requires no less than 4 poles to complete a full N-S period.
• In the same space, I could have double the pole count for ½ of the tooling cost. If it was a linear rail, ok – one tool perhaps, but with AF we’re looking at two wedge shape field orientations, so that’s twice the cost.
• Back iron is pretty cheap.

Nice concept though, in theory. 8)
~KF

 

[Logic11]

This looks interesting for anyone who wants to experiment:
(Access to 3D printer reqd)

It would work as a mid drive motor as is.
It can probably be re designed to fit into modded hub too.

Most interesting is the printable (by the look of it) ferromagnetic plastic "material"

 

[Hummina Shadeeba]

you need to design a custom jig to hold them in place while assembling. Even then I wouldn’t trust glue to hold them and they really want to flip over onto each other and better to do a mechanical lip as part of the rotor holding both sides of magnets. Assembly could be easy if you did it with the lips on either side and a jig to set them into position.

Only benefit seems to be making a lighter rotor as you omit the back iron.

The necessary smaller magnets are more susceptible to demagnetization from high field strength. Could do a quasi-hallbach like posted above. It’s not going to reflect the field nearly as well as a true hallbach with equally sized magnets.

Somewhere on rcgroups there’s testing of lots of different configurations with percentages of how effective they can be.


Also seems worth it to get a hollow shaft if going for lower weight

 

[Hummina Shadeeba]

I believe the patent holder for Halbach Array is the United States Government by way of contract between the United State Department of Energy and the University of California/Lawrence Livermore National Laboratory. I cannot find a patent date earlier than 1995 (patent #5,705,902), although I'm sure one must exist.

Regardless, any industry seeking to use the “device” is bound to strict usage for research or military needs first, and commercially second.

I’m fairly certain that any private individual could make a motor for their own investigation without penalty, though I bet if one tried to go into production there would in short order be a knock at the door by the Men in Black.

For myself exploring AF, I thought I could produce a motor of better efficiency without restoring to Halbach; the simulations indicated higher flux density and reduced cost by employing back iron. Think of it this way:

• Halbach requires no less than 4 poles to complete a full N-S period.
• In the same space, I could have double the pole count for ½ of the tooling cost. If it was a linear rail, ok – one tool perhaps, but with AF we’re looking at two wedge shape field orientations, so that’s twice the cost.
• Back iron is pretty cheap.

Nice concept though, in theory. 8)
~KF

How would someone get permission to sell it? Surely they’re not just saying no one can do it commercially are they? Not that I’m trying to but the legality is unique.

What non-commercial hallbach motor rotors have you seen? Any pics?