Directly cooled electric motor made from polymer materials

Directly cooled electric motor made from polymer materials
Sectional view of the electric motor. The core of the motor is a stator consisting of twelve individual teeth, which are wound upright using a flat wire. Credit: Fraunhofer ICT

Making electric cars lighter also involves reducing the weight of the motor. One way to do that is by constructing it from fiber-reinforced polymer materials. Researchers at the Fraunhofer Institute for Chemical Technology ICT are working together with the Karlsruhe Institute of Technology KIT to develop a new cooling concept that will enable polymers to be used as motor housing materials. And that's not the only advantage of the new cooling concept: it also significantly increases the power density and efficiency of the motor compared to the state of the art.

The two key components of an electric drive train are the electric and the battery. And there are three issues that play a particularly important role when it comes to using an electric motor for eco-friendly mobility: high power density, a compact configuration that fits snugly within the electric vehicle, and high levels of efficiency. As part of the DEmiL project – a German abbreviation that stands for directly-cooled electric motor with integrated lightweight – researchers at Fraunhofer ICT in Pfinztal are now working with the Institute of Vehicle System Technology (FAST) and the Institute of Electrical Engineering (ETI) at Karlsruhe Institute of Technology KIT to develop a novel approach that incorporates direct cooling of the stator and rotor. "An electric motor consists of a rotating rotor and a static stator. The stator contains the copper windings that the electricity flows through – and this is where the majority of electrical losses occur. The novel aspects of our new concept lie in the stator," says Robert Maertens, a researcher at Fraunhofer ICT.

Rectangular flat wire replaces round wire

Design of the directly-cooled electric motor. Credit: Fraunhofer-Gesellschaft

Electric motors have a high efficiency of over 90 percent, which means that a high proportion of the electrical energy is converted into mechanical energy. The remaining 10 percent or so of the electrical energy is lost in the form of . To prevent the motor from overheating, the heat in the stator is currently conducted through a metal housing to a cooling sleeve filled with cold water. In this project, the team of researchers have replaced the round wire with rectangular flat wire that can be wound more tightly in the stator. This creates more space for the cooling channel next to the flat wire winding phases. "In this optimized design, the heat losses can be dissipated through the cooling channel inside the stator, eliminating the need to transport the heat through the metal housing to an exterior cooling sleeve. In fact, you no longer need a cooling sleeve at all in this concept. It offers other benefits, too, including lower thermal inertia and higher continuous output from the motor," says Maertens, explaining some of the advantages of the new system. In addition, the new design incorporates a rotor cooling solution that also allows the rotor's heat loss to be dissipated directly within the motor.

By dissipating the heat close to where it is generated, the project partners were able to construct the entire motor and housing from polymer materials, leading to further advantages. "Polymer housings are lightweight and easier to produce than aluminum housings. They also lend themselves to complex geometries without requiring post-processing, so we made some real savings on overall weight and cost," Maertens says. The metal currently required as a heat conductor can be replaced by polymer materials, which have a low thermal conductivity compared to metals.

The project partners chose to use fiber-reinforced, thermosetting plastics that offer high temperature resistance and high resistance to aggressive coolants. Unlike thermoplastics, thermosets do not swell when they come into contact with chemicals.

Directly cooled electric motor made from polymer materials
Coolant circuit in the stator. Credit: Fraunhofer ICT
Suitable for large series production

The polymer housing is produced in an automated injection molding process. The cycle time for manufacturing the prototypes is currently four minutes. The stators themselves are overmolded with a thermally conductive epoxy resin molding compound in a transfer molding process. The team of researchers chose a design and manufacturing process for the that will allow it to be mass-produced.

The team has already completed the stator assembly and experimentally validated the concept. "We used an electrical current to introduce the amount of heat in the copper windings that would be generated in real operation according to the simulation. We found that we can already dissipate over 80 percent of the expected heat losses. And we already have some promising approaches for dealing with the remaining heat losses of just under 20 percent, for example by optimizing the flow of coolant. We are now at the stage of assembling the rotors and will soon be able to operate the motor on the test bench at the Institute of Electrical Engineering and validate it in real operation," says Maertens, summing up the project's current status.


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Feb 01, 2019
In other words, they threw away the advantages of internal cooling channels by making it out of plastic, and then managed to dissipate only 80% of the expected heat load, making the whole thing not actually work.

This is a perfect example of a tech article where a failure is re-framed as a success.

The electric motor isn't the heaviest thing in an electric car - compared to the 1000 pounds of batteries sitting right next to it. In fact electric motors are already highly optimized components in terms of power density, and a regular car would only need a tiny motor to achieve the ~100 HP needed to drive - if you didn't have to haul along the mass of another small car in batteries.

Feb 01, 2019
https://www.youtu...3QRPGlPc

Take a look at what's inside a Nissan Leaf traction unit. The whole thing is as big as a regular IC-engine. Whoops! Turns out high power electronics don't miniaturize into a tiny box - it takes square inches of copper to conduct kilowatts of power. Then you got all sorts of pumps, hoses, fans, relays, solenoids, and the gearbox.

The charger weighs 60 pounds, the inverter some 30 pounds, and the motor-gearbox 180 lbs. The electric motor itself inside the enclosure probably weighs something like 50 pounds, but it's integral to the structure.

Feb 01, 2019
The Leaf is first generation.

Wake up.

Feb 01, 2019
Between our two EVs,we have traveled over 40,000 miles at NO COST.

Sorry about you polluters who need regular maintenance and emissions checks and gassing up and tune-ups and transmission work.

Feb 01, 2019
The Leaf is first generation.

Wake up.


There's been several generations of the Leaf already. It's been on the market since 2010 - almost a decade ago.

This is the 2018 Nissan Leaf engine unit. Looks exactly the same as the 2013 unit. You'd think that if it was possible to make it smaller and lighter, they would have done so.

http://nextcarrev...gine.jpg


Feb 01, 2019
Here's the motor unit with the battery pack:

https://auto360.d...otor.jpg

The motor unit weighs about 280 lbs, and the battery unit weighs 648 lbs. That's 930 lbs together. It's literally like hauling another vehicle along, or at least 2/3rds of a typical European hatchback.

The reason why the Nissan batteries are so heavy is because they're using LiMnO (AESC) chemistry instead of NCA (Tesla/Panasonic), which makes them less prone to catch fire and blow up.

Guy pokes a screwdriver through a Nissan battery pouch, burns it with a torch. Battery still works:
https://www.youtu...7WycW-7E

Good things come at a cost. Half the capacity per mass compared to Tesla.

Feb 01, 2019
"Between our two EVs,we have traveled over 40,000 miles at NO COST."

@G, could you clarify that, please ? How did you charge the batteries ?
What is the remaining life-time on those batteries ??

Feb 01, 2019
Between our two EVs,we have traveled over 40,000 miles at NO COST.


You mean to say you stole them, because you didn't pay anything for them?

Good thing your EVs are imaginary - otherwise you'd be admitting a crime.

@G, could you clarify that, please ?


He doesn't have any. Last time George Kamburoff claimed to own an e-Golf, people checked him up with the DMV and saw no such person owning such a car, nor anyone nearby. He's also claiming to own a solar system, but the satellite imagery of his home address shows no panels - they're on his neighbor's roof. He now claims to own a Tesla. You can take that with a pitcher of salt.


Feb 01, 2019
Eikka took the word of a liar with a grudge and no character in some argument. He was probably also fooled by Trickle-down and "WMD!".

Since he has my location information, he can look me up on google earth and at the Cal DMV.


Feb 01, 2019
"You mean to say you stole them, because you didn't pay anything for them?"

We both paid for our cars, presumably. How much did it cost you to drive 40,000 miles in your polluter, including oil changes, tune-ups, engine maintenance and transmission work?

Hmmmm?

Feb 01, 2019
Making electric cars lighter also involves reducing the weight of the motor.

Weight isn't an issue for electric cars (not nearly as much as for ICE cars). But where such motors could shine is in the aviation industry where weight does come into play.

The motor heat also isn't, currently (at least in cars), the limiting factor to long sustained high-speed travel,. It's the heat management of the battery.

That said making motors more compact surely has some benefits as it allows designers to get more creative with the rest of the car's layout.

Feb 01, 2019
@Eikka
@gkam

Happy New Year, guys.

Re this exchange between you...

@gkam said:
Between our two EVs, we have traveled over 40,000 miles at NO COST.


@Eikka said:
You mean to say you stole them, because you didn't pay anything for them?


@Eikka, try to make your points without deliberately misconstruing what was said by your interlocutor. @gkam specifically said "travelled" at no cost; he didn't say 'acquired' at no cost. Get the subtle but crucial difference/his point? The context specifically was the electric car's ONGOING 'fuel/running costs', and not the electric car's ONE-OFF 'capital cost' at time of purchase. :)

Also try not to spread 'fake facts' from now-well-known, self-admitted, malicious gangs of personal-insults-and-bot-voting trolls. Do your own 'due diligence'; and resist promulgating 'fake facts' from trolls because it suits your own personal agenda. Else your own personal objectivity/credibility may be irretrievably lost.

Good luck all.

Feb 01, 2019
We both paid for our cars, presumably.
How big a subsidy did you get from the Kenyan? Kalifornicators don't buy anything without using other peoples money.

Feb 02, 2019
@montanaclass.
@gkam said: We both paid for our cars, presumably.
How big a subsidy did you get from the Kenyan? Kalifornicators don't buy anything without using other peoples money.
The fossil fuel/car industries have received many billions in subsidies from govts over the decades. And the damage from pollution has cost us all a lot from mining etc activity that has ruined/poisoned/lost groundwater supplies. The extent of this costly damage from fossil fuel/mining is now become obvious on a global scale. And any subsidy which renewable poser/electric cars may receive, is but a pittance compared to what we have been paying for ICE cars/Coal power production etc. Moreover, any up front subsidies for renewables/electric cars will pay back society/govts manyfold (eg, lower health system costs; lower insurance premiums; increased environmental sustainability; cleaner air/water/food; more safe healthy jobs for longer term). Please inform yourself more fully. :)

Feb 02, 2019
errata: obviously that should read "...renewable power/electric cars...". Thanks.

Feb 02, 2019
Weight isn't an issue for electric cars (not nearly as much as for ICE cars)


Yes it is. It's one of the reasons why you can't have more batteries on-board to driver a longer distance. When you add a ton of batteries on top, the rest of the vehicle's structure has to be made stronger, which reduces performance and increases energy consumption.

The first EVs using lithium batteries that were converted out of regular cars were hitting their curb weight limits to achieve any appreciable range. If any more mass was added, they couldn't have taken on any passengers.

Feb 02, 2019
Also try not to spread 'fake facts'


Gkam is a well-known shyster who has verifiably told so many lies and fables that it doesn't really matter at this point. I know from personally checking some of the stories, such as his lie that he was present at the test-firings of the Saturn-V rocket engine. He's a fake engineer who claims to have been working professionally without an engineering license in California etc. and uses that to claim authority on any subject imaginable. On questions of physics and electronics, he can't demonstrate a basic understanding of concepts and merely regurgitates textbook facts he's dug up from some old presentations and sales pitches on utility power quality management he appears to have given at some point.

He is a pathological liar or demented and delusional. I would take anyone's word before his.

Feb 02, 2019
The context specifically was the electric car's ONGOING 'fuel/running costs'


An electric car's ongoing fuel/running costs are tied to its purchasing price because the battery is part of the consumables - you wear it out by the mile and by the day, which makes it cost an amount of dollars per mile regardless of the power prices.

To say it costs nothing is just pissing on your leg and claiming it's rain.

Feb 02, 2019
@Eikka.
Also try not to spread 'fake facts'
Gkam is a well-known shyster who has verifiably told so many lies and fables that it doesn't really matter at this point. I know from personally checking some of the stories, such as his lie that he was present at the test-firings of the Saturn-V rocket engine. He's a fake engineer who claims to have been working professionally without an engineering license in California etc. and uses that to claim authority on any subject imaginable. On questions of physics and electronics, he can't demonstrate a basic understanding of concepts and merely regurgitates textbook facts he's dug up from some old presentations and sales pitches on utility power quality management he appears to have given at some point. He is a pathological liar or demented and delusional. I would take anyone's word before his.
Can you please post for the @forum your 'evidence' for your claim that @gkam "verifiably told many lies and fables"? Thanks. :)

Feb 02, 2019
@Eikka.
The context specifically was the electric car's ONGOING 'fuel/running costs'


An electric car's ongoing fuel/running costs are tied to its purchasing price because the battery is part of the consumables - you wear it out by the mile and by the day, which makes it cost an amount of dollars per mile regardless of the power prices.

To say it costs nothing is just pissing on your leg and claiming it's rain.
In that vein, an ICE car's motor and drive chain is much more requiring of maintenance/replacement. So all that being equal, the fuel/oil costs are absent from the running costs of Electric vehicles. I suspect (and automatically assumed) that is the context/understanding in which @gkam made his relevant remark:
Between our two EVs, we have traveled over 40,000 miles at NO COST.
Perhaps you two should clarify between you what the issues are and what the understandings are...in that light. Good luck and good thinking to both of you in discussion. :)

Feb 02, 2019
Eikka is just angry because others are smarter and live cleaner and cheaper then he can.

Yeah, I was woken up before morning by the test firing of an F-1 at full power, my first night on the base. Air Force Flight Test Center, Late May, 1966. Did I mention I was Air Force Flight Test Center Airman of the Month for October of that year?

Eikka thinks you need an engineering degree to be an engineer. Nope. He simply does not understand what an engineer does. We are not all design engineers. I was an Electronics Engineer for National Semiconductor, and Plant Engineer in plastics and heavy metals. Then, I was a Research Engineer doing stuff for the guvmunt. Then, I was a Energy Services Engineer for PG&E before going into Technical Services as a Senior Energy Services Engineer and a technical resource for the company and our customers.

I finished up by training Electrical Engineers and other technical folk for power companies and their customers nationwide.


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