
Electric motor design claims remarkable improvements - bmh
https://newatlas.com/linear-labs-hunstable-electric-motor/60974/
======
corodra
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
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
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.

~~~
dzhiurgis
While motor efficiency is 90%, drivetrain is less than that because of
gearbox. This motor claims to remove this inefficiency.

~~~
mikeash
Tesla claims that their drive unit (which includes the motor, inverter, and
gearbox) efficiency on their latest models is 93%.

~~~
londons_explore
Average or peak?

Making something that performs well at freeway speeds, yet also is efficient
when manuvering round a parking lot is hard.

Most companies just hope you don't care about only getting 5% efficiency round
the parking lot, because that isn't a large fraction of your energy budget,
even when it's so inefficient.

~~~
mikeash
No idea! Would it be expected for an electric motor to lose so much efficiency
in that scenario, though? I though the variation was small.

Motor efficiency aside, a total “energy spent for distance moved” accounting
will look bad at such low speeds, just because the car has to power non-motor
systems and they use energy at the same rate no matter how fast you’re moving.
Peak efficiency in a Tesla is at around 25MPH.

------
iamgopal
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
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
I think they must be claiming a 20% improvement on the 90% baseline, otherwise
it doesn't make any sense.

~~~
beojan
That's still impossible. 20% of 90% is 18%.

~~~
callesgg
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%

~~~
microcolonel
20% less energy dissipated as heat.

------
y04nn
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.

------
aetherspawn
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_2...](https://www.cascadiamotion.com/uploads/5/1/3/0/51309945/ss_250-090.pdf)

------
karmakaze
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
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/kostiuchenko1...](https://previews.123rf.com/images/kostiuchenko/kostiuchenko1504/kostiuchenko150400013/39394933-stator-
of-the-electric-motor-isolated-on-white-background.jpg)

[2]: [https://qph.fs.quoracdn.net/main-
qimg-245c5636ff7753478e9348...](https://qph.fs.quoracdn.net/main-
qimg-245c5636ff7753478e9348d0c7688afb)

~~~
adammunich
Hello fellow motor nerd!

------
yholio
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.

~~~
Svip
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?

~~~
hwillis
> Surely the advantage would be the same as for an IC engine.

No. The two types of motor are fundamentally different. Combustion engines
need transmissions because they produce relatively constant torque (within 50%
of max torque). Electric motors on the other hand produce relatively constant
_power_.

This makes total sense when you think about it. An IC engine is powered by
explosions; every explosion produces roughly the same force on the piston
regardless of speed. You can't get more power without more explosions because
you can't cram more air in the cylinder. You can only speed up the engine.

In an electric motor, you can cram as many electrons into the wires as you
want. You are only limited by how much heat is generated. Increasing speed
increases heat slower than increasing torque, but you can still basically
increase either as much as you want.

~~~
blattimwind
> Electric motors on the other hand produce relatively constant power.

Generally speaking, no. P = 2 _pi_ M*n, while the common types of motor used
in electric drives (synchronous and asynchronous three phase machines) will
produce nominal torque at (almost) any speed from 0 (not for asynchronous
machines) to nominal speed; therefore output power is pretty much proportional
to speed.

The only type of motor that comes to mind that has somewhat of a constant-
power behaviour to it are series wound motors.

~~~
hwillis
What you're describing[1] is only true for fixed-voltage controllers. With a
real driver, all motors will behave as I described, even induction motors[2].
The only caveat is that due to saturation and hysteresis there are obvious
nonlinear regions where speed or torque can't be increased. Between those two
regions, all motors are capable of constant power output. Air-core motors are
in theory more ideal, but good luck getting them to behave.

In fact, it's a fundamental property of motors- the power constant. There is a
torque constant (rpm/volt), a torque constant (torque/amp) and a motor
constant that describes the efficiency of transformation from electrical to
mechanical power.

[1]:
[http://raise.spd.louisville.edu/ECE252/images/L19-18.gif](http://raise.spd.louisville.edu/ECE252/images/L19-18.gif)

[2]: [http://www.eeeguide.com/speed-control-of-variable-
frequency-...](http://www.eeeguide.com/speed-control-of-variable-frequency-
induction-motor/)

[3]:
[http://www.motioncomp.com/pdfs/Motor_Constant_Great_Equalize...](http://www.motioncomp.com/pdfs/Motor_Constant_Great_Equalizer.pdf)

~~~
blattimwind
You seem to misunderstand. Let's talk about an 15 kW asynchronous machine with
two poles hooked up to a VFD. At nominal voltage (say 400 V) and nominal
frequency (say 50 Hz) it will produce approx 50 Nm of torque to reach its
nominal power (n ~ 2900 min^-1). Input current will be somewhere around 30 A.
Let's say we want it to run at approx 300 min^-1, thus frequency is reduced to
~5 Hz and voltage to ~40 V. Output torque will still reach approx 50 Nm _at
the same current as it did at 50 Hz_. However, output power is now
approximately 1.5 kW. You _can_ boost low-end torque a little bit, but not by
much (every VFD offers some parameters for this), because this requires
increasing the current.

If we were to run this motor "constant power" at 300 min^-1 it would provide
about 500 N*m of torque and run at a hypothetical current of 300 A -- it's
quite clear that that isn't going to go well.

~~~
hwillis
Sure, there are lots of ways you can make a motor that will mess that up. You
can put in current-limiting fuses. Many motors cool themselves with fans, so
they can dissipate lots of heat at speed and will just burn up if you try to
add torque. You can make windings with insulation that breaks down at low
voltage so the motor can't spin fast.

For big stationary motors that are wound for high voltage, the large number of
turns means copper losses dominate and limit torque at all but the highest
speeds. Nevertheless, those motors can be rewound for lower resistance, which
will cause them to have more even tradeoffs at different voltages/currents.
Rewinding a squirrel cage rotor is... a bit of a task, obviously, but the
torque/voltage constants are always pretty interchangeable.

------
nullwasamistake
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
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.

------
bArray
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/)

~~~
tinco
I'm a total novice to electric motor design, but they mention being able to
switch between simulating phases. I don't think they mean they do higher
torque at lower power input. I think it means that they can transparently
trade efficiency for higher torque, so they can be efficient at low torque,
high speed, while also be able to deliver torque at low speed without
requiring gearing.

I know how marketing departments work, if you have a product that has only one
advantage over the competition, then they'll go and market your product as if
it's the best at every point. I bet they've come up with this design that
eliminates the need for gearing while retaining efficiency at low torque, and
the rest is just marketing jabber.

~~~
natermer
I'm a lay person somewhat familiar with the terminology. I am going to be
wrong on several details.

What they were talking about is phase weakening.

Think of voltage as 'electrical pressure'. Like PSI or Bar.

Think of amperage as 'volume per second' or 'amount of electrons (equivalent
charge) per second'... like liters per minute.

Combine the volume per second by pressure and you get total energy per second;
watts. Hence 'voltage * amps = watts'

Electric motors are also generators. When they spin they create their own
'reverse voltage', sometimes called 'Back EMF', that creates resistance in the
windings of the motor.

The faster the motor spins the greater this 'back emf'. It'll increase until
the 'back emf' creates enough resistance that it effectively negates the
voltage coming from the power source. At that point the motor has reached it's
top speed. This is why DC motors don't try to spin infinitely fast.

The strength of the motor, the torque, is directly related to the amount of
amperage flowing. When the motor is at it's top speed it's generating only
enough torque to overcome the resistance of the bearings and other parasitic
drag. So very little actual current is flowing, especially in a very efficient
motor.

Field weakening is a technique that you can use to overcome some of this
limitation.

What it does is change the shape of the voltage wave. Most of the time on a
oscilloscope it would show up as a sine wave or trapezoid... But if you can
change the timing and peak of the wave then you can effectively weaken the
magnetic field at the right time that the 'back emf' isn't as strong. Sort of
flatten out the peak and make the pulse wider then it normally would be.

So you end up flowing less peak amperage, but overall more amperage. Depending
on the type of motor and speed the amount of extra torque/amperage you can
generate can be very significant. The trade off is reduced efficiency.

A simple motor surface mount magnet may only see a 20-30% increase in top
speed and decrease in torque at the low end. A more modern interior mounted
magnet (were magnets are embedded inside of steel laminates) that combines the
strength of the rare earth magnets with reluctance of the magnetic field
flowing through the steel.. (think of the magnets providing their own force at
low end and then providing a guiding path for magnetic flux as the motor
speeds up) Can see many multiples boost in top speed while still maintaining
significant torque at low end. Field weakening on some motors can produce
increased torque across the entire RPM range.

This is going to be very strongly taken advantage of in EVs like the Tesla
Model 3.

Although in the case of most motors this field weakening is done
electronically, by changing the shape of the waves sent to the motor.

This design does the same thing, but by moving the drum's magnets out of phase
with the magnets on either side. So it's mechanical field weakening.

It's not a super-new concept or anything. I expect their patents have to do
with the 'H' shape of the spindle and the math behind how it is supposed to
work.

I don't know if mechanical field weakening really provides any real benefit
over electronically controlled one.

~~~
bArray
Very interesting, thank you! Do you have more information I can read about
phase weakening and BLDC control algorithms?

I ask because I happen to be designing a BLDC motor controller, I am aware of
using the back EMF to measure the motor phase, but never considered it as a
force slowing the motor down. As a software engineer by trade I was hoping I
could perhaps dynamically switch between the two control techniques to get
low-end torque and high-end speed? I was also hoping to setup the controller
to optimize the various parameters for the specific motor it is controlling by
measuring the back EMF.

Any help is greatly appreciated :)

~~~
balfirevic
Read this:
[https://krex.k-state.edu/dspace/bitstream/handle/2097/1507/J...](https://krex.k-state.edu/dspace/bitstream/handle/2097/1507/JamesMevey2009.pdf;jsessionid=EC8BB0F5202A11CBF4AEE02B0EB2863F?sequence=1)

It's a thesis from James Mavey titled "Sensorless field oriented control of
brushless permanent magney synchronous motors".

Other good resources:

[http://build-its-inprogress.blogspot.com](http://build-its-
inprogress.blogspot.com)

[http://discourse.odriverobotics.com/](http://discourse.odriverobotics.com/)

[https://things-in-motion.blogspot.com](https://things-in-motion.blogspot.com)

------
baybal2
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.

------
cannedslime
Every broken dream starts with a 3D render.

~~~
8bitsrule
Except in love, of course.

~~~
cannedslime
... of course ...

------
nimbius
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)

------
DiabloD3
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
> 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
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/)

------
LargoLasskhyfv
Uhm. *Halbach Cylinder" like in

[1]
[https://en.wikipedia.org/wiki/Halbach_array](https://en.wikipedia.org/wiki/Halbach_array)
?

~~~
hwillis
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.

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

~~~
blattimwind
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
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
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
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
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)

------
raxxorrax
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.

