
Maker of In-Wheel Electric Car Motors Goes to China - rbanffy
https://spectrum.ieee.org/transportation/efficiency/maker-of-inwheel-electric-car-motors-goes-to-china
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matt2000
This article is from 2014 so I thought it would be interesting to see how
things are going.

It's hard to tell whether the subject of the article, Protean, is having
success with the in-wheel motor. Their website is vague about who their
customers are: [http://www.proteanelectric.com/about-
us/](http://www.proteanelectric.com/about-us/)

At the end of the article they mention that China set a goal of 500,000 non-
fossil fuel cars on the road by 2015, it looks like they probably got there:
[https://en.wikipedia.org/wiki/Electric_car_use_by_country#/m...](https://en.wikipedia.org/wiki/Electric_car_use_by_country#/media/File:Top_PEV_global_markets_stock_Dec_2016.png)

They also stated the goal is to have 5M on the road by 2020, which also looks
like they'll get close since there were 352,000 sold in 2016:
[https://qz.com/972897/china-is-selling-more-electric-
vehicle...](https://qz.com/972897/china-is-selling-more-electric-vehicles-
than-the-us-and-its-not-even-close/) and what looks like a 72% growth rate
over 2015. That would mean (if the 72% growth holds, it could even increase):

Current: ~600K 2017: 600K sold 2018: 1M sold 2019: 1.72M sold

Total: ~4M

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metalliqaz
Surely they wouldn't move the motors into the wheels for actual full-size
cars, right? In addition to the poor handling aspects of so much more unsprung
weight, it would have to deal with much more vibration. Seems like a tough
sell.

~~~
phkahler
>> In addition to the poor handling aspects of so much more unsprung weight,
it would have to deal with much more vibration. Seems like a tough sell.

I did some work with hub motors a while back. The unsprung mass is still under
debate, but moving all that mass to the corners of the vehicle is actually a
good thing. I would think putting the inverter in the hub would make for
terrible durability problems, but who knows.

Anecdote: The hub motors I wrote code for had integrated planetary gear, so
they ran 6000rpm at the motor. The rotor was on a rather large bearing and we
had all sorts of runout and alignment issues. It's was really hard to package
in that space. We had peak power of 40KW per wheel, but you only got that for
about 30 seconds before needing to cool off for 5 minutes (it was also water
cooled, but not well - packaging again). Because of the heating and alignment
issues, nobody could make much progress on doing the software calibration
(motor mapping) on it. It was the only motor we had that _required_ my new
algorithm to get it up and running. It made light work of the calibration,
compensated for the alignment and eccentricity issues, and ran the hell out of
that thing. Sometimes I miss working on that stuff ;-)

~~~
2sk21
Whenever I read car magazines they are always talking about the need to reduce
unsprung weight. Supposedly, high unsprung weight causes a harsher ride - so
this is not a given?

~~~
phkahler
Depends. If you hit a bump or a pothole, you need the wheel to move vertically
very quickly. But on smooth roads it's not a problem and having the mass at
the corners increases the vehicles rotational (pitch, roll, and yaw)
stability. I have not formed a personal opinion on it yet, so I listen to both
sides. My suspicion is that the unsprung mass is bad and the arguments to the
contrary are partly wishful thinking by hub-wheel advocates ;-)

~~~
abakker
I always wonder whether it is really inspiring weight, or the ratio of sprung
va unsprung?

In an application I have lots of experience with, mountain biking suspension,
the overall sprung weight relative to the frame/rideris so low that even
doubling the wheel weight or cassette weight doesn’t really effect suspension
performance. (Pedaling rotating mass is a different story)

In a car or truck, where the overall mass of the car is very large, adding
more unsprung mass might not matter so much. The car still has a lot more
inertia than the wheels. You should be able to make up for the heavier wheels
with better suspension valving and improved shims. Problem being that most
factory standard suspension is really bad.

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Animats
It's not a bad idea for heavy trucks. LeTourneau heavy equipment used in-wheel
motors from 1958. They built some monster earthmoving machines with that
technology. It was Diesel-electric all-wheel drive, like a locomotive. Works
fine at big scale, driving very slowly.

LeTourneau built some huge off-road "land trains" for the U.S. Army. The
biggest used multiple gas turbine engines and had 58 powered wheels.[1]

[1]
[https://www.youtube.com/watch?v=Mrt6pVJO468](https://www.youtube.com/watch?v=Mrt6pVJO468)

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Theodores
Michelin have been tinkering away at this for a long time, they have two
motors, one for the drive and one for the active suspension:

[https://en.wikipedia.org/wiki/Active_Wheel](https://en.wikipedia.org/wiki/Active_Wheel)

Their rival Continental have something a lot more interesting:

[https://cleantechnica.com/2017/08/14/continental-new-
wheel-c...](https://cleantechnica.com/2017/08/14/continental-new-wheel-
concept-turns-conventional-wheel-inside/)

They have an aluminium disc with the rotor on the inside, not the outside,
plus the 'spokes' of the wheel hold this oversized disc. The disc does not
rust so it suits EVs where the brakes really should not be needed outside of
emergencies, and when that happens you don't want the wheels to go round a few
times clearing off rust before actual braking kicks in.

I am sure that this can also be combined with better aero so that the hub cap
is designed to radiate heat rather than direct air in to the brake.

I imagine a future where vehicles have an extremely flat and low floor with
the wheels pushed to the corner and definitely 'cab-over' to some extent as no
bonnet needed. This will be great for users of wheelchairs, pushchairs and
hand carts. Particularly if the vehicle drives itself and knows where all the
potholes are and has the active suspension to deal with it.

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gandreani
I'm also dubious. My first impression of the render is, where do the brakes
go?

A car can go without brakes in the rear, but front brakes are crucial in the
front. This is specially true in emergency situations. I doubt an electric
motor can provide enough braking power to stop any car at highway speeds in
the distance required by most countries

~~~
dsfyu404ed
> I doubt an electric motor can provide enough braking power to stop any car
> at highway speeds in the distance required by most countries

This really isn't a problem. A hub motor should have no problem providing more
stopping force than the tire/road interface can manage.

Heat is no problem either. Either dump the excess energy into a battery or
just design a motor housing that can cool itself well enough. You have way
more area and mass in a hub motor than in a brake rotor. You'd almost have to
try to screw it up.

Maximum stopping distance laws are a complete joke. Anything can stop fast the
first time. It's the 5th, 6th, 7th time that's a problem. Electric motors
actually have the advantage in that situation because they fade more linearly
than a hydraulic system.

~~~
tlb
Hitting the brakes in a 2500 kg car at 100 mph generates a megawatt of braking
energy (100 * 1607/3600 * 2500 * 9.8 * 0.9 = 984 kW). Plausibly sized hub
motors can't handle this even momentarily.

Brake rotors have less thermal mass, but can get red-hot without damage.

~~~
gandreani
Another comment in this thread mentioned that the limiting factor is the
MOSFET/Switch in the controller, instead of the motor itself

~~~
abakker
How many actuations is the motor good for? The mosfets? Brakes are great, work
for a very long time, and have lots of redundancy, they are also easy to fix
without diagnosing issues with mosfets, windings, switches, and wires.

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millette
23 years ago in Québec, this happened: [https://fr.wikipedia.org/wiki/Moteur-
roue_d%27Hydro-Qu%C3%A9...](https://fr.wikipedia.org/wiki/Moteur-
roue_d%27Hydro-Qu%C3%A9bec) (in French only). It never went anywhere
unfortunately.

------
dsfyu404ed
I've never been to china but what's their city road quality like?

An extra 70lb at the wheel is going to make the already terrible durability of
low profile tires worse (and you can't design for a smaller rim because you
need space for the motor).

~~~
darawk
Sorry if this is a stupid question, but why would 70lbs in the wheel be any
different from that same weight resting above the wheels, as in a normal car?

~~~
TD-Linux
On the wheel, it's unsprung mass. That extra mass hurts the ability to the
wheel & suspension to quickly respond to bumps, and causes energy to be lost
into the suspension and tire.

It's even a problem on trains - early electric trains had connecting rods
between the motors and wheels just like steam trains. Later ones have the
motors in the bogeys, but the motors are sprung and can swivel on the same
axis as the drive gear.

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rurban
Afaik Magna designed a similar car concept 8 years ago already, but nobody
picked it up. German car makers prototyped similar designs but they had to
move to Chinese companies to get them actually built.

Technically it's easy, much easier to control, much cheaper, but you need the
loading infrastructure (no hybrid, limited range) and strong political
support. Since Israel cancelled their nationwide e-car project, nothing much
happened since, but Tesla.

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misterhtmlcss
Engineering at this level would require a somewhat intelligent engineering
team and so I'm assuming this is their starting point and that they are
expecting to significantly lower the weight.

Having the engine there if these weaknesses are managed effectively would be
quite disruptive to the industry. Maybe they won't make it work, but they
obviously think they can.

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imglorp
Between resistance from the chemical, oil and auto industries, their bought
government, and the more favorable conditions in China, this might be another
core tech we lose forever if we don't pay attention now.

~~~
woodandsteel
Not to worry. Pretty soon the Trump administration will have all our cars
running on coal.

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m3kw9
Maybe use these for trucks and CAT vehicles

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randyrand
So no physical brake?

