This whole thing sounds like a scam. Even worse, it's in an IEEE article. I'm really glad I ended my subscription to them so many years ago if they've fallen to these depths. Just look at this one line from their article:
>Torque is the amount of work that a motor or engine produces, typically measured on a per-revolution basis.
No, that's energy, not torque. Torque is rotational force. Torque times rotation is power, which is the rate of work. Work = energy. This is Engineering 101 here; it's inexcusable for the IEEE of all organizations to screw this up. I expect this kind of lousy journalism from a mainstream, layman news outlet like NBC or something, not something aimed at engineers.
>A typical motor’s copper content could be reduced by 30 percent, while generating equivalent torque, they say. So for a given torque level, the HET consumes significantly less energy than competing designs.
Very little of the electrical energy input to a motor is consumed by resistive losses in the windings; almost all of it is consumed by conversion to mechanical energy. Reducing winding resistance is nice, but it's not going to produce some enormous energy savings. Reducing the weight is helpful too, but again, those extra windings are only a fraction of the motor's weight, and unless the motor is being used in an aircraft, motor weight isn't really that big a deal in a vehicle, battery weight is.
>The company’s permanent-magnet tech requires no rare-earth metals.
This sounds like a total crock. Always be suspicious of new inventions when a single invention claims revolutionary advances in more than one field. Magnet technology is separate from motor technology, just like CPU technology is separate from mobile phone technology: it's a very necessary component, but still a component, one which is usually sourced from an outside vendor. Motor manufacturers do not make their own permanent magnets; there's companies that specialize in that. And making magnets with the highest densities of magnetic flux without rare-earth elements would be a pretty big game-changer, so why are they talking about motor windings instead of this?
>The system incorporates a purely electronic transmission
A what? Not possible: a transmission is a mechanical item that converts rotary motion into rotary motion at a different speed and torque level (e.g., high-speed, low-torque into low-speed, high-torque). This is just a meaningless sound bite. Most EVs use transmissions (usually single-speed "gearboxes", not multi-speed "transmissions") because they'd have to make the motor physically larger to generate the torque necessary to drive a car directly, and the extra weight and size isn't worth it; it's easier to drive motors fast and use a gearbox to gear it down, even with the efficiency loss.
>Many electrified vehicles must also integrate a DC-to-DC converter
Again, the "Institute of Electrical and Electronic Engineers" apparently don't understand basic electronics any more. Most EVs use 3-phase brushless motors, or induction motors (Tesla). The motor controllers are driven by DC because that's what Li-ion batteries produce, and they output waveforms to directly drive the windings on the motor in accordance with the current demand for power. I don't see how they expect to get around some sort of controller here.
Sorry, this whole piece sounds like BS. The whole thing is likely some kind of scam to get investor money and then disappear.
There are a number of goofy marketing-wank sections on there. Written by an engineer, but it's got the ring of someone really stretching to sound innovative.
> As much as 30% of the typical copper needed is reduced by having all the copper in the coil involved in energy conversion.
That's total bullshit. Here's what they're saying: in a typical motor, at least some of the copper will be outside the iron[1]. There's waste associated with that, since you only need current to be flowing exactly around the iron. However, 30% is an order of magnitude high. The stray field from that copper is almost nil, as it will massively prefer to travel through the iron, so the only real worry is that you've just got extra copper. In modern motors the windings are quite tight to the iron and the stator is long axially.
Even in poorly-wound stubby motors like those in ceiling fans[2] you won't be wasting 30%- maybe 10%. The part of the loop going side-to-side is not wasted, only the parts extending up and down away from the iron.
> The structure of the HET ensures that all of the magnetic field interactions are fully involved in the production of torque.
They must have a gap to get in wiring to the stator, so field can escape there. It also goes straight through the magnets. Any gap develops fringing loss essentially regardless of how big it is, so their reduction in loss is small. And stray field loss is already so tiny it can be neglected.
> The unique design requires no unproductive open spaces. Only the air gap surrounding the coil is left open.
And I wonder how tight their air gap actually is, with all those cantilevered magnets and moving parts. Probably not great. Plus, there's a ton of empty space inside the rotor. They do use the stator iron slightly more efficiently, but in normal motors that space is usually used for bolts anyway.
> Unlike existing conventional machines where torque is only present at an optimum point as it approaches a magnetic pole, the HET has no single optimum point but rather all positions exhibit maximum torque.
> The torque and force will exist while the coil is in the tunnel, regardless of tunnel length.
Well that's just blatantly not true, and also the crossover point between poles is going to be very wiggly indeed. The stator is going to be stretching and compressing itself at different points and the flux has to travel from pole to pole regardless of how many coils are in the way. Their design lets them trade off between torque and speed more easily, but all the rest is nonsense.
> Another advantage is that phases can be software controlled to be grouped into particular patterns. For example, phases A and B can be controlled to act as a single larger pole. Likewise, C, D, E and F. Conversely other groupings are possible with A, B, and C or D, E and F acting as single poles.
Any high-slot motor can be run like this. It's very rarely done because the cost of adding more phases is immensely high. Doubling the number of phases can be multiple times more expensive than doubling the power. And for variable three-phase motor systems the driver is already the most expensive part. If they need all those coils, that's a big problem. TBH though this bit is probably what won them investors- people may be interested in applying their simulation and controls work to conventional motors. It would be deeply challenging to add more slots to the current gold standard motor (PM-reluctance), but it could potentially lead to more high-end efficiency.
> In both of the above cases there is a radical drop in efficiency. The HET Motor addresses this need in a completely different manner. By slightly rotating a single side rotor, an axial magnetic component is introduced. This weakens, as far as the coils are concerned, the total magnetic field experienced by the coils. The degree of field weakening controls the tradeoff between torque and speed.
> For the first time in electric machine history, as the HET Motor enters the Constant Horsepower Region, core losses drop and overall efficiencies actually climb!
Hmm. Yeah, I could believe it. They're also introducing slew, but that's not terrible. It also makes it easier on the driver. However, this would be ungodly expensive.
> So, in the magnet-less design, are they saying that you are more efficient because your motor won't pull away energy/speed when not powered? As opposed to a permanent-magnet design, where you have to constantly add energy to maintain speed?
Yes. And the magnetless motors are still able to regen when you want to slow down.
It looks like scam and smells like scam, but it may not be: http://www.qe.fi/ . I get this idea of motor windings as removable preprinted modules. Low/High voltages and other clueless shit looks less valid, as there are active devices to adjust voltages and match impedances.
I agree that they are at least misrepresenting their achievement. However, for the sake of argument, electric motor efficiency goes down quite a lot as overall power potential and RPM both drop. So it's possible they've come up with a sizeable efficiency improvement in a worst-case scenario, i.e., improving efficiency of a small motor in low RPM, part throttle situations.
If that's the case, however, it doesn't really bode well for them, as their efficiency gains will not translate to the high-RPM, high-power motors used in cars. I'm not EE, but I do know that most engineering involves making trade-offs. So I wouldn't be surprised to learn that techniques to improve low-power, low-RPM efficiency probably sacrifices high-power, high-RPM efficiency.
Yeah, it sounds like they're saying they get the efficiency of a permanent magnet motor (which can be around 95% or so) without using magnets. Induction motors I think tend to be in the high 80's.
I don't entirely buy the rare earths thing. You can buy permanent magnet EV motors without rare earths, like the Netgain Hyper9 [1] (which I'm using in a conversion I've been working on for awhile). The hyper9 is kind of heavy for its power density, though, so maybe that's the advantage of rare earth magnets. If this company can get the efficiency of a permanent magnet motor but without rare earths and at a high power density, maybe they've got something new and interesting.
edit: another advantage of avoiding magnets is that they tend to demagnetize if they get too hot. Not having magnets means you might be able to run the motor hotter without damage. Though, a 95% efficient motor should be pretty easy to keep cool.
The most I understand about motors is how they typically work and that innovations are possibly more lucrative than battery innovations; this seems like a major innovation. I must be missing something? What's the healthy skepticism here?
>its high torque, available over a magnificently wide band of motor speeds
A broad torque curve isn't really useful since aircraft engines are already optimized for sustained operation at cruising speed and the range of speeds you can operate at is limited by the propeller and physics. There's no need to have a ton of torque at 1800rpm and at 6000rpm
>At 20 kilograms (45 pounds), the motor can be held in two hands, and it measures only 10 centimeters deep and 30 cm in diameter
And what's the horsepower rating and duty cycle rating on this motor? Power density is not an area where electric motors have a large advantage over ICE unless you're trying to build a cylindrical package. The article talks about doing away with durability requirements that impede a lightweight design.
>with no power-sapping transmission
Most small aircraft are direct drive.
Electric power certainly has advantages but this article may as well be a marketing brochure full of fluff.
I've learned a great deal about motors over the years. I don't doubt what they have here is real, as, these principles have been known for a long time.
The reason we don't use permanent-magnet synchronous motors like this in cars though, is because rare earth magnets are much more expensive, and more fragile, than using synchronous reluctance motors which are mostly iron.
The auto companies aren't dumb --if they thought PMS motors were cost effective, they would have been using them by now.
The commenters saying that this is old news and that magnet-free brushless motors have existed for a long time miss the main point. ZF claims to have one that is competitive with traditional designs utilizing rare earth materials.
Even ten to fifteen years ago the effort German automakers put into saving a milligram Dysprosium here and there - not only in the drive motor but every electric motor in the vehicle - was insane. I'm out of automotive for a couple of years now, but I can only imagine that this pains must have increased dramatically.
Because of all this effort, a motor without rare earth metals would only have to be nearly as good as the competition to still be a huge deal.
Permanent magnet motors sometimes use rare-earths. It's not absolutely necessary, but going without may lose some power and/or increase the weight. Induction motors don't need permanent magnets, but they're less efficient so the EV industry seems to be moving away from them. (Less efficient also means they generate more heat, which means more active cooling.)
EV motors often have absurdly high RPM limits, which may require some exotic materials and/or lubricants. (I think Tesla motors go up to about 18,000 rpm if memory serves.)
Copper for the windings is another high-cost material; copper has been expensive lately. You could use aluminum instead, but it would mean having to scale up the design or run at a lower power to compensate for the wire resistance.
I do hope to see good, cheap, powerful motors be a thing that was more available to random third parties to swap into their old ICE vehicles. Right now the best options seem to be to use something like a Netgain Hyper9, or scavange a drive unit out of something like a Leaf or Bolt or Tesla.
> The HET is a three-dimensional, circumferential flux, exterior
> permanent magnet electric motor with some interesting
> characteristics. For starters, it runs four rotors where other motors
> typically run one or two. The stator is fully encapsulated in a four
> sided "magnetic torque tunnel," each side having the same polarity,
> ensuring that all magnetic fields are in the direction of motion, and
> there are no unused ends on the copper coils wasting energy. All
> magnetism the system creates is thus used to create motion, and all
> four sides of the stator contribute torque to the output.
I'm not so sure about the idea that "unused ends" are "wasting energy". Simply put your finger on a small spinning motor and watch the current go up - increase the work done, increase the power usage. Typical losses in magnetic motors are:
1. Friction - Bearings, brushes, etc
2. Air - Typically cooling
3. Core - Hysteresis (changing polarity is not possible instantly) and eddy current losses (unwanted current flow)
4. Resistance - The coils themselves resist high current
Brushless motors are typically 85-90% efficient and brushed typically reach 75-80% efficiency [1]. Reducing the size a little, sure, but increasing the torque - I highly doubt for the same power input. I'm sure we will get to 95% efficiency within the next 10 years or so (with big money from the automotive industry pushing research), but it's highly unlikely we will get more than that outside of the a lab with super-cooled conductors.
Which is the other thing, increasing the amount of torque and reducing the size means greater heat generation. Any saving in size you're getting gets lost again just keeping the motor cool.
Anyway, the promises don't pass basic scrutiny, I would definitely need to see some numbers on this. It sounds like snake oil.
EDIT: Another thing - electric motors are already very efficient, you're getting more loss in other parts, such as voltage regulators, motor control circuitry, batteries (if you're using them), cooling, etc, etc. I just don't think this will translate to a massive improvement.
Tesla used induction motors and even got funding from Toyota to develop them as a rare earth free design. But permanent magnet motors can be more efficient, and newer Tesla motors use permanent magnets. (Unless I’m very much mistaken, Tesla’s PM motor has no windings in the rotor.)
There are plenty of motor designs with neither slip rings nor brushes. I don’t see what’s special about this supposedly new design.
If having fewer magnets means less rare earth consumption for the same performance, then that's a benefit in itself - the same one as is being claimed for this motor.
To be fair, is practically on one of the first lines of the press release: "...In contrast to the magnet-free concepts of so-called separately excited synchronous motors (SESM) already available today..."
> I just want to mention that improving motor efficiency would also help with some of the other losses you mention.
It's not that simple. Increases in torque are strongly associated with increases in current- torque is directly proportional to total magnetic flux, so more torque in a smaller package generally means more current in your wires. The alternative is to add more turns of thinner wire, but thinner wire has lower packing efficiency.
Losses from current rise as RI^2 in simple wires, slightly faster in transistors, and some very complex factor in batteries that I can't remember but is between I^3 and I^4. You can make a 100% efficient motor, but if it quadruples the current draw then it will be almost useless for vehicles.
>Torque is the amount of work that a motor or engine produces, typically measured on a per-revolution basis.
No, that's energy, not torque. Torque is rotational force. Torque times rotation is power, which is the rate of work. Work = energy. This is Engineering 101 here; it's inexcusable for the IEEE of all organizations to screw this up. I expect this kind of lousy journalism from a mainstream, layman news outlet like NBC or something, not something aimed at engineers.
>A typical motor’s copper content could be reduced by 30 percent, while generating equivalent torque, they say. So for a given torque level, the HET consumes significantly less energy than competing designs.
Very little of the electrical energy input to a motor is consumed by resistive losses in the windings; almost all of it is consumed by conversion to mechanical energy. Reducing winding resistance is nice, but it's not going to produce some enormous energy savings. Reducing the weight is helpful too, but again, those extra windings are only a fraction of the motor's weight, and unless the motor is being used in an aircraft, motor weight isn't really that big a deal in a vehicle, battery weight is.
>The company’s permanent-magnet tech requires no rare-earth metals.
This sounds like a total crock. Always be suspicious of new inventions when a single invention claims revolutionary advances in more than one field. Magnet technology is separate from motor technology, just like CPU technology is separate from mobile phone technology: it's a very necessary component, but still a component, one which is usually sourced from an outside vendor. Motor manufacturers do not make their own permanent magnets; there's companies that specialize in that. And making magnets with the highest densities of magnetic flux without rare-earth elements would be a pretty big game-changer, so why are they talking about motor windings instead of this?
>The system incorporates a purely electronic transmission
A what? Not possible: a transmission is a mechanical item that converts rotary motion into rotary motion at a different speed and torque level (e.g., high-speed, low-torque into low-speed, high-torque). This is just a meaningless sound bite. Most EVs use transmissions (usually single-speed "gearboxes", not multi-speed "transmissions") because they'd have to make the motor physically larger to generate the torque necessary to drive a car directly, and the extra weight and size isn't worth it; it's easier to drive motors fast and use a gearbox to gear it down, even with the efficiency loss.
>Many electrified vehicles must also integrate a DC-to-DC converter
Again, the "Institute of Electrical and Electronic Engineers" apparently don't understand basic electronics any more. Most EVs use 3-phase brushless motors, or induction motors (Tesla). The motor controllers are driven by DC because that's what Li-ion batteries produce, and they output waveforms to directly drive the windings on the motor in accordance with the current demand for power. I don't see how they expect to get around some sort of controller here.
Sorry, this whole piece sounds like BS. The whole thing is likely some kind of scam to get investor money and then disappear.
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