Automotive

Mahle's cheap, highly efficient new EV motor uses no magnets

Mahle's cheap, highly efficien...
Mahle's highly efficient new electric motor ditches rare earth metals altogether, instead using contactless induction to feed power to coils in the rotor
Mahle's highly efficient new electric motor ditches rare earth metals altogether, instead using contactless induction to feed power to coils in the rotor
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Mahle's highly efficient new electric motor ditches rare earth metals altogether, instead using contactless induction to feed power to coils in the rotor
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Mahle's highly efficient new electric motor ditches rare earth metals altogether, instead using contactless induction to feed power to coils in the rotor
Rather than magnets, the rotor uses wound coils
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Rather than magnets, the rotor uses wound coils
A wireless transmitter sends power to the rotor, using an alternating field that's converted into direct current for the magnet coils
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A wireless transmitter sends power to the rotor, using an alternating field that's converted into direct current for the magnet coils
The ability to continuously tune the magnetism of the coils in the rotor has enabled Mahle to make this a super-efficient electric motor across all operating speeds, particularly excelling at high speeds
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The ability to continuously tune the magnetism of the coils in the rotor has enabled Mahle to make this a super-efficient electric motor across all operating speeds, particularly excelling at high speeds
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Magnets, typically using rare earth metals like neodymium, are found at the heart of most electric vehicle motors. It's nice to have a permanent source of powerful rare earth magnetism in your rotor, because using powered coils instead means you have to somehow transfer electricity from the battery through to the coils in a spinning rotor. That means you'll need a sliding point of contact, and sliding points of contact develop wear and tear over time.

Permanent magnets, though, come with their own baggage. Ninety seven percent of the world's rare earth metal supply comes out of China, and state control over such a crucial resource across a number of high-tech industries has been a serious issue in the past. Official accounts differ about why China decided to restrict rare earth exports back at the start of the decade, as official accounts tend to do, but the result either way was a 750-percent leap in neodymium prices and a 2,000-percent leap in dysprosium prices.

Could these metals be produced elsewhere? Yes. They're not as rare as the name might suggest. But wherever they're mined, the only way to economically turn them into magnets is to send them to China for processing – nowhere else in the world is set up for the task, and nobody can compete against China's minimal labor costs and environmental regulations.

So it's a heavy bat China can swing in trade negotiations, and a genuine supply line security issue for other countries. Several companies, including BMW, Audi, Renault and others, are making at least some of their electric motors without magnets already; everyone else has their eye on new technology in this area.

And that's the context into which German company Mahle has just announced a new electric motor that sounds like it solves a lot of problems in a very tidy manner.

Rather than magnets, the rotor uses wound coils
Rather than magnets, the rotor uses wound coils

The new Mahle design uses no magnets, instead using powered coils in its rotor. Unlike previous efforts, it transfers power to the spinning rotor using contactless induction – so there are basically no wear surfaces. This should make it extremely durable – not that electric motors have a reputation for needing much maintenance.

The lack of expensive metals should make it cheaper to manufacture than typical permanent-magnet motors. Mahle says the ability to tune and change the parameters of the rotor's magnetism instead of being stuck with what a permanent magnet offers has allowed its engineers to achieve efficiencies above 95 percent right through the range of operating speeds – "a level that has only been achieved by Formula E racing cars."

It's also particularly efficient at high speeds, so it could help squeeze a few extra miles out of a battery in normal use. The company says it'll scale nicely from sizes relevant to compact cars up to commercial vehicles.

A wireless transmitter sends power to the rotor, using an alternating field that's converted into direct current for the magnet coils
A wireless transmitter sends power to the rotor, using an alternating field that's converted into direct current for the magnet coils

“Our magnet-free motor can certainly be described as a breakthrough, because it provides several advantages that have not yet been combined in a product of this type,” says Dr. Martin Berger, Mahle's VP of Corporate Research and Advanced Engineering. “As a result, we can offer our customers a product with outstanding efficiency at a comparatively low cost.”

Mass production is about two and a half years away, according to IEEE Spectrum, and Mahle has not yet nominated which auto manufacturers it's dealing with, but test samples are already starting to circulate.

Source: Mahle via IEEE Spectrum

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26 comments
26 comments
Daishi
Fun fact, the induction motor was invented by Nikola Tesla. The first electric automobile that I know of that used one was GM's EV1 but induction motors powered most Tesla vehicles until the Model 3. The issue with brushless permanent magnet motors that Tesla was seeking to overcome is when you have powerful magnets but don't run the motor at high power the fixed magnets providing the B magnetic field are disproportionally powerful to the lower power being send through the windings leading to sub-optimal operation for automotive application where you are very rarely at maximum power outputs. This is better explained by former Tesla Engineer Wally Rippel in a 2007 blog post here ( https://www.tesla.com/blog/induction-versus-dc-brushless-motors ). Tesla redesigned the motor in the Model 3 to a brushless permanent magnet system called IPM-SynRM that uses a mind-bending method to overcome the B field magnetic efficiency losses described by Wally if you care to go down that rabbit hole on Youtube.
ChairmanLMAO
The problem with free energy is patents.
piperTom
Thanks to Daishi for the info on motor competition and to Wally Rippel for exposition of all the factors that need to be considered. Still, the key phrase for the description of this new motor is that a "wireless transmitter sends power to the rotor". Thus we find a simplified description of the new motor: take an old-fashioned DC brush motor, then replace the brushes with a wireless transmitter and a rectifier.
SibylTheHeretic
Awesome. Now if they can just make the batteries cheaper and with longer range I might be able to afford an electric vehicle.
Don Duncan
"Rare earth metals" are only rare because of politics. The biggest mine WAS in Nevada, but was closed by the Greenies.
Mahle has no motor, only a prototype. According to Musk, it's 200 times harder to go from a prototype BEV to production. But 2.5 years? For just a motor? Is Mahle soliciting investors? Do they have the patients?
gettodacessna
That is fantastic! It makes so much sense. Cannot wait to see a demo!
Ornery Johnson
Interesting historical insight, there Daishi. It seems to me that the key development of Mahale's system is they tweek the amount of power used to induce magnetism in the rotor windings. My guess is that this improves efficiency by allowing them to better "match" induced magnetism in the rotor windings to the total motor power output required at any given moment.
Thomas Gilfoyle
How does this compare with Turntide's new switched reluctance motor, a very simple construction with inexpensive metals but precise computer controls? It claims energy savings of beyond 50%.
Ruby Mc
this type of motor is already in production and use commercially by a company named Turntide Technologies although their thrust has been to invade the commercial hvac space. Nothing new here except that mahle is concentrating on ev space
VincentWolf
I can imagine in the future most every electric motor will be made this way. Dumping the rare Earths is a big deal.
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