Skip to comments.A Push to Make Motors With Fewer Rare Earths
Posted on 04/22/2012 8:17:27 PM PDT by neverdem
FOR much of the last century, the straightforward solution to making a car perform better has been to install a bigger engine. In the hybrids and electric cars of coming years, however, the answer might be installing motors with more powerful magnets.
Until the 1980s, the most powerful magnets available were those made from an alloy containing samarium and cobalt. But mining and processing those metals presented challenges: samarium, one of 17 so-called rare earth elements, was costly to refine, and most cobalt came from mines in unstable regions of Africa.
In 1982, when researchers at General Motors developed a magnet based on neodymium, it seemed that an ideal alternative had arrived. While neodymium is also one of the rare earth metals a misleading name, as they are actually fairly common, just widely dispersed it is more abundant than samarium, and at the time it was cheaper. When combined with iron and boron, both readily available elements, it produced mighty magnets...
(Excerpt) Read more at nytimes.com ...
I just want to celebrate ping. Thanks neverdem.
one of Obama’s donors must’ve just cornered the market on neodymium
“Hey Big Brother...”
Copper or Aluminum, and Iron, are all you need to make a motor (and an insulator like lacquer or ceramics).
Yes, you can build lighter/more efficient motors from permanent magnets, but that efficiency only holds at lower RPMs. Higher RPMs and permanent magnet brushless motors begin to suffer from Eddy current losses in the large monolithic magnets that make up the armateur of the motor. Their efficieny begins to drop as their speed increases and the drive power frequency increases.
Induction motors have much more leeway in terms of high speed operation... they require only good design principles for the stator and armateur, and metals that aren’t too special in nature. Induction motors are also more reselient to overheating. If you don’t put enough heat into the stator to melt the insulation on the windings, you can keep pushing power into them. Permanent magnet motors will begin to have their permanent magnets degrade in strength.
On the other hand, I thought there was a push to start mining rare-earths from the ocean. Anyone know what came of this?
Personally, if I was a car company not in China’s special graces, I’d focus on induction motors. Until more precious metals supplies come online, precious metals are going to be pricey.
Many will recall the controversy when Magnequench was sold to the China consortium in 2000 and the factory was disassembled and moved to China.
All this came on the heels of the MolyCorp rare earth mine having their new permits delayed because of the pipline rupture and spill.
Of course, the concept of removing EPA restrictions on mining for rare earths domestically would never occur to anyone.
MolyCorp, the only rare earth mine in the US, is located on private property, so the County Planning Commission is the lead agency and has more authority than either the federal agency(EPA) or the state enviro agency. An Environmental Impact Report is required.
But if you want to locate your mine on BLM land then you will have to deal with EPA and you will be required to have an Environmental Impact Statement.
My favorite was “Get Ready”.
Induction motors require AC current, which is kind of nonsensical to create from DC batteries in electric cars.
Most DC-to-AC converters produce square waves that don’t play well with induction motors, and pure sine wave DC-to-AC converters are inefficient.
In the previous decade, with less efficient switching devices, that was a concern, however with current igbt devices, it’s not a problem.
Additionally, bldc motors in anything bigger than a rc car are generally sinewave driven anyway, to reduce stator energy loss, audible noise, and problems with smoothness of torque delivery.
Driving a 100hp motor with a square wave would ring a car body like a drum.
Thank you for your expertise! Would it be practical to build a linear motor such that half the motor is in the road bed and the lighter half would be on the bottom on the car? Possibly any car could be turned into a hybrid by mounting a permanent magnet on the bottom then have the road bed pull the car along magnetically. Another option is pass electric power from the road bed to the car inductively. That way the car doesn't need a 700 lb. battery on board for power. It could use its conventional motor when not on a high volume specially equipped highway. If the future is electric cars we're going to have to build more power distribution, so why not built it right into the road bed?
I seriously doubt the practicality of distributing power via the road surface. Not only that, but as a conservative type, having my mobility that easily controlled by the government, is severely disconcerting.
I think we aren’t there yet on electrics, not because of drive technologies and magnet materials, but energy storage. It is the big blocker. Rare earth elements and their low speed motor efficiency wouldn’t even be a consideration if we could store a large amount of power in a battery or capacitor bank in the car. Not even the weight of the battery would be a factor, if it could easily store enough power to make it’s own mass and the accompanying inertial factor be negligible.
The advancement that makes that happen could happen tomorrow, or it could be decades from now. But my theory is...
It will result as a by product of the companies currently making rechargeable vehicles driving their development teams to outdue their competitors. I actually think this will be the biggest point of innovation in batteries, and good electric vehicles will eventually come on the market and take over, and it won’t be dramatic, it’s just that eventually your next car, and the best car, will the electric one because of steady plodding advances.
That is, if electric vehicles can survive when the subsidies for electric vehicles are removed, and keep refining the technology on a regular pace.
I don’t think electric vehicle technology should be government subsidized. Of course, there are some that say we are subsidizing oil now, and if we are, those incentives should be removed as well, then oil vs. electricity in the transportation sector could compete on their actual costs, not their government modified costs.
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