The headline is about the reduced neodymium content but the most interesting part of the development is good high-temperature performance without requiring any terbium or dysprosium. Additions of those expensive, almost-exclusively-China-produced rare earth elements have been how neodymium magnets are made suitable for high-power, high-temperature applications in motors and generators. Neodymium, cerium, and lanthanum are more common rare earth elements that have more good mineral resources outside China.
Most wind turbines use electromagnets in their generators, plus gearing systems. So-called "direct drive" turbines use high strength permanent magnets and can have longer lifetimes since the gearbox is the fastest-degrading part of conventional turbines. But turbines with permanent magnet generators have been only a minority of the market, in part because affordable and assured supplies of key heavy rare earth elements are not available outside China. (Goldwind, the only wind turbine manufacturer presently with an all-direct-drive lineup, is Chinese.) Powerful magnets with less need for rare materials can improve wind turbines to charge EVs as well as motors to move them.
While innovation to substitute an expensive ingredient from a potentially unreliable supplier is laudable, from a chemist/metallurgist point of view I wish there was more innovation in mining and cleaning up the process of getting rare earth in the first place. Every rare earth element increases option value and the potential to make further progress.
The main reason rare earth are expensive is that they mining is done in decades old tech fashion, and dirty as hell. China does not seem to mind as much, as long as it is controlling a strategic resource. Finding higher concentration deposits, and improving the process of extracting the rare earths elements is something I wish to happen more of...
Those are moonshot companies; if they work they'd have the potential to bring in trillions worth of minerals from space, but before they get there they'll probably require hundreds of billions of investment first. Plus they'd destabilize the market.
No doubt this innovation will occur once cheap and dirty mining practices are banned globally. Until then, any slightly more expensive and clean method has to compete with the cheap and dirty, and in the mining business, that makes you non-competitive fast.
I am very curious how they create grains of the cerium and then coat them with neodymium to then fuse them together.
I theorize that they first alloy the cerium and lanthanum together and then grind it to a correct particle size. Then they negatively electrically charge the rare earth particles and bond neodymium to it with vapor deposition but I don't know it that is possible at that scale.
They would then press the particles together and heat them up so that they fuse but don't liquify.
All of this looks very very cool I just have no concept for how it would actually happen.
Never mind, I just found the answer to my own question but I find it interesting none the less. So as the solution of the three metals cool if done correctly the neodymium will come out of solution to form a mesh of neodymium around the grains of cerium and lanthanum in a similar way that pearlite forms from austinite and ferrite in steel. This will give them a "sponge" of neodymium to conduct the magnetic field but have the cerium and lanthanum act as filler.
To explain what I am talking about way better than I ever could, this video is how heat treating steel will change it's properties and why different steels act the way they do.
https://youtu.be/6jQ4y0LK1kY
If memory serves, in standard Nd-B-Fe magnets the neodymium also concentrates at the grain boundary in the same way. My guess is that the Ce/La is acting as a stabilizer for the internal structure replacing Nd that would otherwise have been stuck inside the crystallite.
Copper induction motors use no magnets at all. 20 years ago, the control algorithms and power electronics required were prohibitive, but the tech now seems fundamentally superior to permanent magnet motors.
Why are magnetic motors of such interest to Toyota?
For several reasons. One of them is that induction motors don't work as a generator, their torque/speed curve is bad as well
And magnets instead of electromagnets allow you to have brushless motors. You could go with a synchronous motor but I guess the efficiency is not very good
You are incorrect. Induction machines are often used as generators. My employer uses them almost exclusively in the generator configuration. The Lorentz force is symmetric; in the generator mode of operation the magnetizing flux vector leads the torque-producing current vector instead of lags, but the physics still works the same.
The induction torque speed curve is also very performant even when compared to PM machines so I don’t understand your criticism. Source: motor control engineer.
You can use an induction machine as a generator, but it has to be connected to the grid. It will generate reactive power. You need a rotor field to generate power. In a permanent magnet machine this field comes from the magnet, but in an induction machine this comes from the motion of the stator field (Lenz' Law).
To maybe put it another way, there is no way to charge a dead battery with an induction machine.
> You can use an induction machine as a generator, but it has to be connected to the grid.
That's not true.
> You need a rotor field to generate power.
Residual magnetic field is enough to start the process, absent that a quick DC zap will do.
> In a permanent magnet machine this field comes from the magnet, but in an induction machine this comes from the motion of the stator field (Lenz' Law).
Yes. Fortunately rotors retain a bit of magnetism after you run them to a stop, which is enough to get things going again later on.
> To maybe put it another way, there is no way to charge a dead battery with an induction machine.
Yes there is, unless the induction machine is fresh from the factory and has never run at all.
The rotors of induction machines are usually copper, which is not ferromagnetic and will not have any remanent magnetization. In practical terms it is not feasible to "bootstrap" an induction machine in the way that you describe.
You're simply wrong. Again. The rotor windings of induction machines are usually copper or aluminum, the stator windings are usually copper.
As for the rotors and stators themselves, they are good old iron/steel laminates and will hold some magnetism just fine (they're laminates to cut down on the eddy currents). If the rotors themselves would be made out of copper the motor would not function at all, it needs a ferromagnetic part there to focus the field.
Source: have done a number of induction motor to windmill conversions. Also: have you ever tried any of this or are you coming at this from a theoretical angle?
Well, there was that time when I was getting an EE degree where I asked my drives professor if I could use an induction motor as a generator, and that's the response he gave.
With all respect for your professor, you could of course simply try rather than echoing words from long ago.
Fortunately not everybody will take 'it can't be done' as the final answer :) It's not what can't be done in theory that matters but what can be done in practice.
If you battery is dead and your engine isn't running, isn't the battery the priority anyway? Having backup batteries to provide initial excitation for generators should not be difficult. They just need to start it, afterwards you can use the output for self-excitation. Worst case, you'd just use a tiny PM generator to bootstrap the process.
I think there are other more significant trade-offs between induction and PM motors. Induction motors/generators are significantly heavier, and have significantly lower torque (i.e. can extract less lower at low speeds when used as generator). Their main attractiveness comes from lower cost, reliability, and decent efficiency at high speeds.
I stand corrected about not being able to use induction motors as generators, still
As per wikipedia
> An induction generator produces electrical power when its rotor is turned faster than the synchronous speed... An induction generator usually draws its excitation power from an electrical grid
Which is not what they want in a car
Also they do want good torque at zero speeds, while it can be done with induction motors it's not ideal
> Today, all the hybrids are powered by DC brushless drives, with no exceptions. The only notable uses of induction drives have been the General Motors EV-1; the AC Propulsion vehicles, including the tzero; and the Tesla Roadster.
> Induction machines are more difficult to control. The control laws are more complex and difficult to understand. Achieving stability over the entire torque-speed range and over temperature is more difficult with induction than with DC brushless. This means added development costs, but likely little or no recurring costs.
A hybrid has different characteristics and requirements from the motor than a purely electrical vehicle as well
Yes, induction machines do draw power in order to establish a magnetic field where as PM machines get it for "free" by virtue of the magnets. Also the torque production at zero speed is almost identical in induction machines vs. PM machines, so this isn't an issue.
For EV applications one of the cool things about induction machines is that they can actually achieve higher efficiency at high speeds than a PM machine. This is because at high speeds the spinning magnets in a PM machine induce losses (so called eddy-current and hysteresis losses) which are difficult to suppress. In an induction machine you are controlling the field directly so it can be weakened at higher speeds with a control loop to directly optimize the losses vs. torque production. This means that there is a trade-off speed at which an induction machine becomes more efficient than a comparable PM machine.
To mitigate this issue in PMs some vehicle manufacturers have tried to do cool tricks like partially demagnetizing the magnets at high speeds to reduce losses, but this is very difficult to do without damaging the magnets permanently.
Motor size is approximately proportional to torque, not power, so you can imagine a small, low torque induction machine that is fast and will have better efficiencies than a corresponding PM machine. In stop and go traffic or low speed travel the PM machine typically has better efficiencies.
Personally I hope in the long run we end up with induction machines in our electric cars. 1) No safety issues with spinning magnets at high speed during an inverter failure, 2) no reliance on rare-earth materials, 3) the control of induction machines is very cool in its complexity and gives an additional degree of freedom on field flux that is only partially controllable in PM machines, and 4) induction machines have longer lifetimes as there is practically nothing to wear out aside from the bearings.
Yes but apparently the Model 3 uses permanent magnet motors. I would be interested to see the detailed engineering trade offs between these two choices.
Only because of efficiency different. Even Tesla now uses pm bldc, when their earlier models are induction. ( The irony. ). I hope they do more research to increase the efficiency of induction motor instead of giving it up to china.
Neodymium starts to lose magnetivity above 80C, and ICE usually run at a higher temperature than this.
Don’t forget Toyota is probably the biggest manufacturer of hybrid engines, and in their setup the cooling fluid runs through both the ICE and electric motors.
Cooling fins or fans only help for long-term thermal performance. When you floor a Tesla, the motor can be safely driven for a short time, and nothing goes wrong if it gets hot (other than lower efficiency due to increased resistance). If you did the same thing in a permanent car, you risk demagnetising the motor.
I used to work at a company that makes pumps with magnetic bearings. To pump hot liquids, we needed special magnets with higher Curie temperatures than traditional Neodymium magnets. Our high-temperature products had Samarium-Cobalt magnets and ran, if memory serves, up to almost 200°C.
Neodymium-iron-boron magnets can have a higher energy product than samarium-cobalt, but require additions of expensive/rare heavy rare earth elements to work well at elevated temperatures. (Or require special microstructure modifications like Toyota has developed.) SmCo magnets have had good high temperature performance from the beginning, but a lower energy product.
Other issues that discourage widespread substitution of SmCo magnets for NIB:
Tried to read it on the phone. Got a huge blank page, with a few chat heads.
Wish people stick with basic HTML if they don't know what they're doing...
I think HN may need a link up top next to the `favorite' link labeled `talk' like on Wikipedia.
So,
23 points by philipkglass 5 hours ago | flag | hide | past | web | favorite | 9 comments
would become,
23 points by philipkglass 5 hours ago | flag | hide | past | web | favorite | talk | 9 comments
That's where people and bots could post comments about the HTML/JS/CSS issues of the page in question and anything off-topic but page or site related. Come to think of it the talk page could also be where people could post "Yeah but Crystal" comments on Ruby threads and "Elon Musk is not all that" on SpaceX or Tesla threads. I honestly think this could reduce a good deal of the meta chatter on HN. Where could I go to prototype the idea? What do other think?
Most wind turbines use electromagnets in their generators, plus gearing systems. So-called "direct drive" turbines use high strength permanent magnets and can have longer lifetimes since the gearbox is the fastest-degrading part of conventional turbines. But turbines with permanent magnet generators have been only a minority of the market, in part because affordable and assured supplies of key heavy rare earth elements are not available outside China. (Goldwind, the only wind turbine manufacturer presently with an all-direct-drive lineup, is Chinese.) Powerful magnets with less need for rare materials can improve wind turbines to charge EVs as well as motors to move them.