14 ms·

Electric motor design claims remarkable improvements

164 points by bmh 7y ago

DiabloD3 7y ago
This article might not be well written. What they describe I'm pretty sure I read about something very similar to this in the 90s, and as far as I can tell, never took off; either I am right, and I indeed read about this before, or the article is describing it badly. PR statement via CNET as the source isn't helping, either.
- bArray 7y ago
  > I'm pretty sure I read about something very similar to this in the 90s, Can you give more information please? I too highly doubt what they're selling here, would be interested to know what the previous efforts were.
  - SaintGhurka 7y ago
    They might be referring to something like Chorus Motors[0]. I don't know anything about electric motors, but Chorus has been around since the 90s and make similar sounding claims. I'll quote their technology summary[0] "The Chorus Star concept utilizes concentrated, high phase order windings which allows the beneficial use of harmonics (temporal, spatial, and overload). Consequently, a Chorus machine can achieve much higher torque densities than a traditional 3 phase motor, but with no cost penalty. Chorus Star machines are superior to three-phase machines as well as permanent-magnet machines". They make (or are trying to make) a nose-gear mounted assembly for airplanes so you can drive a 737 around with just the APU running - not using the main engines[1]. Also they let pilots pull back from the gate without waiting for a tug on the ground. The claim is that their motor allows them to fit enough torque into the nose wheel to do the job, whereas a conventional motor couldn't do it. [0] http://www.chorusmotors.com/technology/exec_summary.php http://www.chorusmotors.com/technology/exec_summary.php [2] http://www.wheeltug.com/ http://www.wheeltug.com/
iamgopal 7y ago
How cooling of rotor being achieved ? Energy, power and torque density of other motor designs are limited by their cooling capacity. Reluctance motor being externally cooled, has this as a prime selling point. I think for claimed improvement, it will need external cooling which is not mentioned in article.
- phkahler 7y ago
  There's a lot not mentioned. How do they move the rotor magnets in field weakening? How do they reconfigure the coils? How do they get 20 percent more efficiency when most are already over 90-95 percent?
  - Mvandenbergh 7y ago
    I think they must be claiming a 20% improvement on the 90% baseline, otherwise it doesn't make any sense.
    - marvin 7y ago
      Once again emphasizing the importance of separating between percent and percentage point :P
    - randallsquared 7y ago
      So, 90% improved to 92%? That's not nothin'...
    - beojan 7y ago
      That's still impossible. 20% of 90% is 18%.
      - callesgg 7y ago
        A 20% improvent would be a 20% closer to 100% specifically 20% out of the remaining 10% so 2% overall improvement. From 90% to 92%
yholio 7y ago
Electric cars don't usually have "gearboxes" proper. They use gears, fixed ratio reductors. This is not expensive nor is it fragile nor bulky nor inefficient. The benefits that a very high torque motor could bring are real but marginal, a few percentage points improvements on the respective metrics. They could instantly be negated by, say, the lower initial reliability of a revolutionary design.
- IshKebab 7y ago
  The article mentions that.
  - yholio 7y ago
    And then goes on to make outlandish claims about the benefits of the technology
    - IshKebab 7y ago
      Also true, but I didn't say otherwise.
      - yholio 7y ago
        Meanwhile, I logically built on the same point to present a contrarian opinion, so your initial reply is somewhat pointless nitpicking. It's exactly what the author of the article intended, making a passing reference to the fundamental flaw thet invalidates the rest of the hype contained. It's not even a conspiracy, it's standard clickbaity journalism, a balanced article about a possible 3% efficiency boost would not make it to HN front-page.
- Svip 7y ago
  I am genuinely curious, why aren't there transmissions for electric engines? Surely the advantage would be the same as for an IC engine. I remember hearing that Tesla tried to build a 2 speed transmission for their Roadster back in the day, but apparently it kept breaking, so they stuck with no transmission. Are there transmissions out there for EVs, and I just haven't been paying attention? And if no, why is it so hard? Is it because of the torque?
aetherspawn 7y ago
The video shows a picture of a motor about 99% similar to that of Cascadia Motion [1] based on the external appearance and cooling apparatus and not at all similar to the picture in the article. 1: https://www.cascadiamotion.com/uploads/5/1/3/0/51309945/ss_250-090.pdf https://www.cascadiamotion.com/uploads/5/1/3/0/51309945/ss_2...
bArray 7y ago
Feel free to educate me... > 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. [1] http://dronenodes.com/drone-motors-brushless-guide/ http://dronenodes.com/drone-motors-brushless-guide/
- codeflo 7y ago
  I agree about the article, I just want to mention that improving motor efficiency would also help with some of the other losses you mention. Going from 80% to 90% means that you need half as much cooling, batteries may be more efficient when you draw less power from them, etc. That might it worth it even if the motor efficiency gain alone doesn’t look like much on paper.
shadowbanme 7y ago
> How cooling of rotor being achieved ? How construct grammatical sentence?
LargoLasskhyfv 7y ago
Uhm. *Halbach Cylinder" like in [1] https://en.wikipedia.org/wiki/Halbach_array https://en.wikipedia.org/wiki/Halbach_array ?
- Geee 7y ago
  Tesla uses Halbach array magnets in their motors. It's explained here (this guy discovered it by accident): https://www.youtube.com/watch?v=aVnRQRdePp4&t=641 https://www.youtube.com/watch?v=aVnRQRdePp4&t=641
- hwillis 7y ago
  No, doesn't look like. Halbach arrays use magnets in different directions to smoothly redirect a field; you can do the same thing with iron or soft steel. Since the field on the back side of the magnets is basically static it doesnt cost any efficiency and its much cheaper. Halbach arrays are sometimes used in motors that need to be very light, like very specialty high-acceleration brushless motors.
baybal2 7y ago
No absolute figure given, so it feels at least fishy. I doubt that the current record of 10kw per kilogram is beatable by any significant extend. This is limited much by limits of material science, and not electromagnetics. Those 10kw/kg motors fully utilise close to like 80% of the flux, so much bigger advancements from geometry change are unlikely.
raxxorrax 7y ago
Perhaps we could just use standard steppers if we reduce real life frames per second. But they do have torque at most frequencies compared to conventional designs, so I think this could work.
deleted 7y ago
[deleted]
mrfusion 7y ago
I’ve always wondered why no one is researching motors that use electric fields instead of magnetic?
- blattimwind 7y ago
  There are electrostatic motors, it's just that they aren't particularly interesting (low power density, very high drive voltages, poor efficiency). They do have one interesting property, which is that at zero speed they can develop nominal torque without using any power (unlike say a synchronous servo).
  - mrfusion 7y ago
    How much of that is just a matter of more R&D though? I don’t see why any of that is inherent to electrostatic?
    - blattimwind 7y ago
      It's mostly Coulomb's law; electrostatic force is proportional to the involved charges divided by their separation. You don't have that problem in electromagnetic motors because strong magnetic fields don't break down the rotor/stator air gap. You might turn the air gap into a dielectric oil gap, but now you have fluid friction losses which again limit how narrow that gap can be. You'll note that this is a recurring pattern with electromagnetic vs. electrostatic implementations of roughly the same idea.
      - mrfusion 7y ago
        Good explanation. So it makes me wonder if we could improve on the capacitor if we could find its magnetic counterpart. Does that even make sense?
        hwillis 7y ago
        like... an inductor? Inductors and capacitors are opposite in behavior, but a series capacitor can be replaced with a parallel inductor and vice versa. In that sense they are counterparts. It is not possible to make an inductor out of purely passive capacitive components, or vice versa. In fact the Gyrator[1] is a transistor circuit that exists specifically to act like an large inductor using capacitors, which are cheaper to build at large values. The function of a Gyrator inherently requires active power input; it isn't possible to passively convert the phase lag of a magnetic circuit into the phase lead of a capacitive circuit. [1]: https://en.wikipedia.org/wiki/Gyrator https://en.wikipedia.org/wiki/Gyrator
corodra 7y ago
Don't get me wrong, I saw the title and was excited. I want this to be real. I want to believe. But way too many keyword drops. Disruptive is what red flagged me the most. Way too many promises. Only lab results and "experts" commenting that it should work in theory. But no prototype? Even though it's a different motor they don't "believe" it's going to cost more to make than traditional motors? Only 3d renders? I think there was a medical company that did something similar with blood testing. Didn't really work out for them.
- sunstone 7y ago
  Electric motors are remarkably good already. Even if it doubled the power for half the weight you still need lug along all those batteries.
  - mikeash 7y ago
    Right, look at the size of the motor versus the size of the batteries in an electric car. Efficiency is already well over 90%, too. If you managed to create an idealized electric motor that was 100% efficient, had no limits on power, torque, or RPM, weighed nothing, took up no space, and cost nothing, it would be a nice improvement but I don't think even this would revolutionize electric cars. Batteries are the key.
    - xxpor 7y ago
      According to people on the TMC forums (so take with a grain of salt) Tesla's motors only cost $350-400. If that's true, they're basically perfect already. It's the batteries which drive cost and weight.
      - adammunich 7y ago
        They are mostly iron so it seems plausible.
      - moogly 7y ago
        Is that the Model 3 motors? I've heard that the Model S motors had a surprisingly high failure rate, many owners of the earlier models having had 5+ drive unit replacements. I'm guessing the Model 3 drive units are more reliable?
y04nn 7y ago
A brief history of the evolution of designs of electric motor from the beginning to the electric motor as we know it today be by Professor Eric Laithwaite: https://www.youtube.com/watch?v=f5mA4l6xmGs https://www.youtube.com/watch?v=f5mA4l6xmGs And the explication of his linear motor for the second half.
karmakaze 7y ago
Their site[0] has an animation of their 4-pole design and describes some advantages. https://www.linearlabsinc.com/why-our-motor/ https://www.linearlabsinc.com/why-our-motor/
- hwillis 7y ago
  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. [1]: https://previews.123rf.com/images/kostiuchenko/kostiuchenko1504/kostiuchenko150400013/39394933-stator-of-the-electric-motor-isolated-on-white-background.jpg https://previews.123rf.com/images/kostiuchenko/kostiuchenko1... [2]: https://qph.fs.quoracdn.net/main-qimg-245c5636ff7753478e9348d0c7688afb https://qph.fs.quoracdn.net/main-qimg-245c5636ff7753478e9348...
cannedslime 7y ago
Every broken dream starts with a 3D render.
- 8bitsrule 7y ago
  Except in love, of course.
  - cannedslime 7y ago
    ... of course ...
nullwasamistake 7y ago
This reads like BS. They mention increases in efficiency like it matters when electic motors are already ~95% efficient. They mention cogging as a problem, when everyone solved that a decade ago by using FOC drivers. It does field weakening by physically rotating part of itself? That doesn't sound like a good idea. At all. A single reduction gear is complex and heavy? Uh no, its probably the cheapest part of the motor
- tgtweak 7y ago
  I think that those "95% efficient" motors are not 95% efficient at all speeds and loads. From what I can grasp, the variable configuration of the rotors let's them trade speed and torque without any loss in efficiency by changing the energizing patterns in the controller. The reduction gearbox is pretty simple in design but it adds one extra component to fail, and it adds weight. I'm curious to see if they can make the controller simple (cheap, reliable, efficient) - that seems to be the next immediate challenge. Cool project for sure, the patents have a fair bit of good information on them. They also have a functioning prototype which is good for a company at this stage. See 60 seconds in here: https://youtu.be/yqIKZGx-06Y https://youtu.be/yqIKZGx-06Y I think waiting two years to get them into a car is a bit of a miss in terms of roadmap.
nimbius 7y ago
maybe not in this case, but from a history of machining, motors have made quiet and remarkable strides. original cone lathes for metalworking were driven by steam engines and a PTO driveshaft. aside from being ridiculously dangerous to operate, they had inconsistent results for tight tolerances. It wasnt unheard of for watchmakers to also find themselves as lathemakers in the early 20th century. Motor speed from PTO was largely not variable. During WWII motor speed was controlled with a clutch and transmission system, which arguably allowed for the type of finesse and control you need to run a shaper for a large tank engine, or a mill for certain explosives of the nuclear persuasion. older machinists handbooks will still reference your 'gear' when making a cut as a feed rate suggestion. old shapers still have a gearbox and shifter. along comes the VSM and its a game changer. The variable motor speed can control RPM maximum down to almost zero RPM. In the early 20th century, this simply was not possible. Previously if you wanted to change speed you had to park/reset the lathe and dial your tolerances back in. The way around gear speed change time was to intentionally oversize the part and take it to an automatic filer, but this wears down files and is only an option for certain manufacturers that care about the end product more than the tool wear (WWII again)

164 points by bmh 7y ago

This article might not be well written. What they describe I'm pretty sure I read about something very similar to this in the 90s, and as far as I can tell, never took off; either I am right, and I indeed read about this before, or the article is describing it badly. PR statement via CNET as the source isn't helping, either.

bArray 7y ago
> I'm pretty sure I read about something very similar to this in the 90s, Can you give more information please? I too highly doubt what they're selling here, would be interested to know what the previous efforts were.
- SaintGhurka 7y ago
  They might be referring to something like Chorus Motors[0]. I don't know anything about electric motors, but Chorus has been around since the 90s and make similar sounding claims. I'll quote their technology summary[0] "The Chorus Star concept utilizes concentrated, high phase order windings which allows the beneficial use of harmonics (temporal, spatial, and overload). Consequently, a Chorus machine can achieve much higher torque densities than a traditional 3 phase motor, but with no cost penalty. Chorus Star machines are superior to three-phase machines as well as permanent-magnet machines". They make (or are trying to make) a nose-gear mounted assembly for airplanes so you can drive a 737 around with just the APU running - not using the main engines[1]. Also they let pilots pull back from the gate without waiting for a tug on the ground. The claim is that their motor allows them to fit enough torque into the nose wheel to do the job, whereas a conventional motor couldn't do it. [0] http://www.chorusmotors.com/technology/exec_summary.php http://www.chorusmotors.com/technology/exec_summary.php [2] http://www.wheeltug.com/ http://www.wheeltug.com/

iamgopal 7y ago

How cooling of rotor being achieved ? Energy, power and torque density of other motor designs are limited by their cooling capacity. Reluctance motor being externally cooled, has this as a prime selling point. I think for claimed improvement, it will need external cooling which is not mentioned in article.

phkahler 7y ago
There's a lot not mentioned. How do they move the rotor magnets in field weakening? How do they reconfigure the coils? How do they get 20 percent more efficiency when most are already over 90-95 percent?
- Mvandenbergh 7y ago
  I think they must be claiming a 20% improvement on the 90% baseline, otherwise it doesn't make any sense.
  - marvin 7y ago
    Once again emphasizing the importance of separating between percent and percentage point :P
  - randallsquared 7y ago
    So, 90% improved to 92%? That's not nothin'...
  - beojan 7y ago
    That's still impossible. 20% of 90% is 18%.
    - callesgg 7y ago
      A 20% improvent would be a 20% closer to 100% specifically 20% out of the remaining 10% so 2% overall improvement. From 90% to 92%

yholio 7y ago

Electric cars don't usually have "gearboxes" proper. They use gears, fixed ratio reductors. This is not expensive nor is it fragile nor bulky nor inefficient. The benefits that a very high torque motor could bring are real but marginal, a few percentage points improvements on the respective metrics. They could instantly be negated by, say, the lower initial reliability of a revolutionary design.

IshKebab 7y ago
The article mentions that.
- yholio 7y ago
  And then goes on to make outlandish claims about the benefits of the technology
  - IshKebab 7y ago
    Also true, but I didn't say otherwise.
    - yholio 7y ago
      Meanwhile, I logically built on the same point to present a contrarian opinion, so your initial reply is somewhat pointless nitpicking. It's exactly what the author of the article intended, making a passing reference to the fundamental flaw thet invalidates the rest of the hype contained. It's not even a conspiracy, it's standard clickbaity journalism, a balanced article about a possible 3% efficiency boost would not make it to HN front-page.
Svip 7y ago
I am genuinely curious, why aren't there transmissions for electric engines? Surely the advantage would be the same as for an IC engine. I remember hearing that Tesla tried to build a 2 speed transmission for their Roadster back in the day, but apparently it kept breaking, so they stuck with no transmission. Are there transmissions out there for EVs, and I just haven't been paying attention? And if no, why is it so hard? Is it because of the torque?

aetherspawn 7y ago

The video shows a picture of a motor about 99% similar to that of Cascadia Motion [1] based on the external appearance and cooling apparatus and not at all similar to the picture in the article. 1: https://www.cascadiamotion.com/uploads/5/1/3/0/51309945/ss_250-090.pdf https://www.cascadiamotion.com/uploads/5/1/3/0/51309945/ss_2...

bArray 7y ago

Feel free to educate me... > 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. [1] http://dronenodes.com/drone-motors-brushless-guide/ http://dronenodes.com/drone-motors-brushless-guide/

codeflo 7y ago
I agree about the article, I just want to mention that improving motor efficiency would also help with some of the other losses you mention. Going from 80% to 90% means that you need half as much cooling, batteries may be more efficient when you draw less power from them, etc. That might it worth it even if the motor efficiency gain alone doesn’t look like much on paper.

shadowbanme 7y ago

> How cooling of rotor being achieved ? How construct grammatical sentence?

LargoLasskhyfv 7y ago

Uhm. *Halbach Cylinder" like in [1] https://en.wikipedia.org/wiki/Halbach_array https://en.wikipedia.org/wiki/Halbach_array ?

Geee 7y ago
Tesla uses Halbach array magnets in their motors. It's explained here (this guy discovered it by accident): https://www.youtube.com/watch?v=aVnRQRdePp4&t=641 https://www.youtube.com/watch?v=aVnRQRdePp4&t=641
hwillis 7y ago
No, doesn't look like. Halbach arrays use magnets in different directions to smoothly redirect a field; you can do the same thing with iron or soft steel. Since the field on the back side of the magnets is basically static it doesnt cost any efficiency and its much cheaper. Halbach arrays are sometimes used in motors that need to be very light, like very specialty high-acceleration brushless motors.

baybal2 7y ago

No absolute figure given, so it feels at least fishy. I doubt that the current record of 10kw per kilogram is beatable by any significant extend. This is limited much by limits of material science, and not electromagnetics. Those 10kw/kg motors fully utilise close to like 80% of the flux, so much bigger advancements from geometry change are unlikely.

raxxorrax 7y ago

Perhaps we could just use standard steppers if we reduce real life frames per second. But they do have torque at most frequencies compared to conventional designs, so I think this could work.

deleted 7y ago

[deleted]

mrfusion 7y ago

I’ve always wondered why no one is researching motors that use electric fields instead of magnetic?

blattimwind 7y ago
There are electrostatic motors, it's just that they aren't particularly interesting (low power density, very high drive voltages, poor efficiency). They do have one interesting property, which is that at zero speed they can develop nominal torque without using any power (unlike say a synchronous servo).
- mrfusion 7y ago
  How much of that is just a matter of more R&D though? I don’t see why any of that is inherent to electrostatic?
  - blattimwind 7y ago
    It's mostly Coulomb's law; electrostatic force is proportional to the involved charges divided by their separation. You don't have that problem in electromagnetic motors because strong magnetic fields don't break down the rotor/stator air gap. You might turn the air gap into a dielectric oil gap, but now you have fluid friction losses which again limit how narrow that gap can be. You'll note that this is a recurring pattern with electromagnetic vs. electrostatic implementations of roughly the same idea.
    - mrfusion 7y ago
      Good explanation. So it makes me wonder if we could improve on the capacitor if we could find its magnetic counterpart. Does that even make sense?
      - hwillis 7y ago
        like... an inductor? Inductors and capacitors are opposite in behavior, but a series capacitor can be replaced with a parallel inductor and vice versa. In that sense they are counterparts. It is not possible to make an inductor out of purely passive capacitive components, or vice versa. In fact the Gyrator[1] is a transistor circuit that exists specifically to act like an large inductor using capacitors, which are cheaper to build at large values. The function of a Gyrator inherently requires active power input; it isn't possible to passively convert the phase lag of a magnetic circuit into the phase lead of a capacitive circuit. [1]: https://en.wikipedia.org/wiki/Gyrator https://en.wikipedia.org/wiki/Gyrator

corodra 7y ago

Don't get me wrong, I saw the title and was excited. I want this to be real. I want to believe. But way too many keyword drops. Disruptive is what red flagged me the most. Way too many promises. Only lab results and "experts" commenting that it should work in theory. But no prototype? Even though it's a different motor they don't "believe" it's going to cost more to make than traditional motors? Only 3d renders? I think there was a medical company that did something similar with blood testing. Didn't really work out for them.

sunstone 7y ago
Electric motors are remarkably good already. Even if it doubled the power for half the weight you still need lug along all those batteries.
- mikeash 7y ago
  Right, look at the size of the motor versus the size of the batteries in an electric car. Efficiency is already well over 90%, too. If you managed to create an idealized electric motor that was 100% efficient, had no limits on power, torque, or RPM, weighed nothing, took up no space, and cost nothing, it would be a nice improvement but I don't think even this would revolutionize electric cars. Batteries are the key.
  - xxpor 7y ago
    According to people on the TMC forums (so take with a grain of salt) Tesla's motors only cost $350-400. If that's true, they're basically perfect already. It's the batteries which drive cost and weight.
    - adammunich 7y ago
      They are mostly iron so it seems plausible.
    - moogly 7y ago
      Is that the Model 3 motors? I've heard that the Model S motors had a surprisingly high failure rate, many owners of the earlier models having had 5+ drive unit replacements. I'm guessing the Model 3 drive units are more reliable?

y04nn 7y ago

A brief history of the evolution of designs of electric motor from the beginning to the electric motor as we know it today be by Professor Eric Laithwaite: https://www.youtube.com/watch?v=f5mA4l6xmGs https://www.youtube.com/watch?v=f5mA4l6xmGs And the explication of his linear motor for the second half.

karmakaze 7y ago

Their site[0] has an animation of their 4-pole design and describes some advantages. https://www.linearlabsinc.com/why-our-motor/ https://www.linearlabsinc.com/why-our-motor/

hwillis 7y ago
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. [1]: https://previews.123rf.com/images/kostiuchenko/kostiuchenko1504/kostiuchenko150400013/39394933-stator-of-the-electric-motor-isolated-on-white-background.jpg https://previews.123rf.com/images/kostiuchenko/kostiuchenko1... [2]: https://qph.fs.quoracdn.net/main-qimg-245c5636ff7753478e9348d0c7688afb https://qph.fs.quoracdn.net/main-qimg-245c5636ff7753478e9348...

cannedslime 7y ago

Every broken dream starts with a 3D render.

8bitsrule 7y ago
Except in love, of course.
- cannedslime 7y ago
  ... of course ...

nullwasamistake 7y ago

This reads like BS. They mention increases in efficiency like it matters when electic motors are already ~95% efficient. They mention cogging as a problem, when everyone solved that a decade ago by using FOC drivers. It does field weakening by physically rotating part of itself? That doesn't sound like a good idea. At all. A single reduction gear is complex and heavy? Uh no, its probably the cheapest part of the motor

tgtweak 7y ago
I think that those "95% efficient" motors are not 95% efficient at all speeds and loads. From what I can grasp, the variable configuration of the rotors let's them trade speed and torque without any loss in efficiency by changing the energizing patterns in the controller. The reduction gearbox is pretty simple in design but it adds one extra component to fail, and it adds weight. I'm curious to see if they can make the controller simple (cheap, reliable, efficient) - that seems to be the next immediate challenge. Cool project for sure, the patents have a fair bit of good information on them. They also have a functioning prototype which is good for a company at this stage. See 60 seconds in here: https://youtu.be/yqIKZGx-06Y https://youtu.be/yqIKZGx-06Y I think waiting two years to get them into a car is a bit of a miss in terms of roadmap.

nimbius 7y ago

maybe not in this case, but from a history of machining, motors have made quiet and remarkable strides. original cone lathes for metalworking were driven by steam engines and a PTO driveshaft. aside from being ridiculously dangerous to operate, they had inconsistent results for tight tolerances. It wasnt unheard of for watchmakers to also find themselves as lathemakers in the early 20th century. Motor speed from PTO was largely not variable. During WWII motor speed was controlled with a clutch and transmission system, which arguably allowed for the type of finesse and control you need to run a shaper for a large tank engine, or a mill for certain explosives of the nuclear persuasion. older machinists handbooks will still reference your 'gear' when making a cut as a feed rate suggestion. old shapers still have a gearbox and shifter. along comes the VSM and its a game changer. The variable motor speed can control RPM maximum down to almost zero RPM. In the early 20th century, this simply was not possible. Previously if you wanted to change speed you had to park/reset the lathe and dial your tolerances back in. The way around gear speed change time was to intentionally oversize the part and take it to an automatic filer, but this wears down files and is only an option for certain manufacturers that care about the end product more than the tool wear (WWII again)