One of the most obvious ways to mitigate the effect of the high cost of REEs is to eliminate rare earth magnets and return to conventional materials. With conventional radial designs, however, that means going back to the bad old days of large, heavy motors. This is because conventional materials simply cannot produce the same field strength as rare earth alloys.
Neodymium iron boron (NdFeB), for example, features an energy product -- essentially, a measure of field strength -- of around 55 MGOe, compared to roughly 4.5 MGOe for ferrite. That bump in energy product is what makes it possible for radial rare earth motors to deliver lots of muscle in a tiny package compared to their ferrite counterparts. The solution required taking a different approach to the problem.
Figure 2: The stator assembly consists of six of these laminated-steel field poles, each surrounded by a bobbin-wound coil. (Source: NovaTorque)
The design starts with a stator assembly formed of six laminated field poles of oriented steel, each threaded through a bobbin-wound coil (see figure 2). The rotor consists of two separate conical ferromagnet assemblies designed to match the cavities on the ends of the stator, leaving a conical air gap. Now, instead of the interaction taking place in two dimensions, it takes place in three dimensions.
If we compare the cross-sectional area of the stator at the coils with the surface area of the laminated pole structure, the ratio is roughly 2:1. This leads to a correspondingly large increase in flux density for the same motor diameter. What that means is that even with ferrite magnet material, the axial design can deliver similar torque density compared to a radial designs based on REE magnets.
“By concentrating flux in three dimensions, we can use quite a bit of low-cost ferrite material and concentrate flux to get a flux density in the stator that is comparable to what you would have in a rare earth magnet motor," says Alan Crapo, vice president of engineering at NovaTorque Inc. Essentially, the approach flips the conventional model of moderate Φs and very high ΦR to moderate ΦR and very high Φs. The result is better performance from conventional materials. “We can get the same kind of efficiency as rare earth magnet motors and we can operate the steel at similar flux density levels that rare earth magnets will operate at," says Crapo.
There are tradeoffs, of course. Even with the flux focusing, the axial designs need more of the conventional magnet material to get the desired performance. The NovaTorque team added more magnet material without significantly increasing frame size by narrowing the air gap between rotor and stator. In addition, the team potted the stator to enhance heat transfer. The result is a motor that may maintain a competitive frame size but more of the overall volume is filled with motor materials, giving it more mass and inertia than its rare earth counterparts.
Sorry but RE motors are not close to many times smaller than other types. They won't be replaced by ferrite magnets but by far better tech like Telsa's and the EV-1's motors that use no RE and smaller than a similar RE motor. No?
So much hype and little substance here.
The article on UC's is far worse, just pure hype by the manufacturer. I can't wait to see his response. It should be enlightening for all of us.
Speculators do not stabilize prices, they create bubbles. Markets stabilize prices only when those bidding on the commodity have an actual stake in the commodity and not merely whether others will pay more for the commodity later than they did.
Unless the speculator can take delivery of teh materials in question, I think that he cannot 'hoard' materials, but will predict the future pirce of an item.
Now the increase in cost to us (the USA) recently may really indicate the 'real' devaluation of the Dollar vs. the Yuan.
Good point, ChasChas. I would imagine a craft could be build in orbit, much like the space station was. Then rockets would only be necessary to ferry passengers back and forth to the craft. Getting the payload from the craft down to earth could be tricky.
I can't speak for Warren, but in an earlier post, I mentioned that there are about 110,000 or more Chinese students here at any given time taking our technology to China. It would be fair to send these students home until China opens up thier rare earth markets again.
The Chinese have been appropriating our technology with our full approval (remember IBM selling Lenovo their PC business?) due in large part to our policies developed to increase profits for corporations. We're our own worst enemy, the Chinese simply take advantage of our lack of foresight and greed. Also, our colleges make money catering to foreign students and I doubt that they'd not send lobbyists to Congress if there were any such attempt to send Chinese students home.
The fact is that REE in China are the property of the Chinese, and as they are their resource, they have a good argument as to controlling their export and we chose to send our technology to China because it brought a few well connected people more wealth. Perhaps we'd have more trade leverage had we not given China so much in the first place.
Maybe it's time to re-engineer our society to be far more efficient such that we don't require REE and conventional magnets can produce what we need. Oh, and reconsider our trade and business policies such that they don't benefit only a few. As far as I'm concerned this is all about sustainability.
The rare earths problem will take care of itself over the next few years. Now that prices have gone up -- due to China's rationing -- it is now affordable to mine rare earths here and in Australia. Soon Afghanistan will come online as well.
Is that you,mom?
Government IS the source of all our problems. Their central planning and over regulation causes constant and severe problems. They can't be ignored, and more of us need to be ranting and not just sitting on our butts complaining about those who are concerned. Mom.
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