Automotive

Mahle's new SCT electric motor runs non-stop at over 90% of peak power

Mahle's new SCT electric motor runs non-stop at over 90% of peak power
The Superior Continuous Torque (SCT) motor punches harder for longer, allowing EV designers to run smaller, lighter electric motors
The Superior Continuous Torque (SCT) motor punches harder for longer, allowing EV designers to run smaller, lighter electric motors
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The Superior Continuous Torque (SCT) motor punches harder for longer, allowing EV designers to run smaller, lighter electric motors
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The Superior Continuous Torque (SCT) motor punches harder for longer, allowing EV designers to run smaller, lighter electric motors
The prototype SCT motors use neodymium magnets in their rotors, but this cooling concept will also work with Mahle's magnet-free motor technology
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The prototype SCT motors use neodymium magnets in their rotors, but this cooling concept will also work with Mahle's magnet-free motor technology

Tier-one auto parts supplier Mahle has announced a groundbreaking "superior continuous torque" (SCT) motor for electric vehicles, capable of continuously pounding out more than 90 percent of its peak power without overheating – and it'll work without magnets.

Electric motors, unlike combustion engines, are often specified with separate peak and continuous (or nominal) power ratings. That's because running them flat-out for long periods can generate enough heat to damage components, so manufacturers build in thermal limiting systems that reduce power output down to the continuous level when they start overheating. The difference between the peak and continuous figures reflects the performance of the motor cooling system.

Here are a couple of examples. At the cheaper end of the scale would be something like the e-motor in the Ox Patagonia electric motorcycle. Peaking at 11 kW, it's so badly cooled that it can only handle a continuous 6 kW – 55 percent of the peak power. Energica's fancy new EMCE motor, on the other hand, peaks at 126 kW, but can handle a continuous 110 kW (87 percent of the peak) thanks to a very effective cooling system.

Mahle – a huge German parts supplier consistently posting sales over US$10 billion a year – says its new SCT motor takes things up a notch, with continuous power ratings over 90 percent of the peak. It uses an innovative oil cooling system that draws in oil through a central intake, then uses the centrifugal force of the spinning rotor to pump the oil up and around the stator coils surrounding it. The heat drawn out can be harvested for use elsewhere around the vehicle if required, or extracted through a radiator.

The result, says the company, is an exceptionally compact, light and efficient electric motor capable of handling sustained high-power situations that would previously have called for much bigger motors with much higher peak power ratings. This, says Mahle, is a motor that can haul a big electric truck up a long, steep mountain pass without dropping power, or handle some serious racetrack abuse in a performance car.

The prototype SCT motors use neodymium magnets in their rotors, but this cooling concept will also work with Mahle's magnet-free motor technology
The prototype SCT motors use neodymium magnets in their rotors, but this cooling concept will also work with Mahle's magnet-free motor technology

Running smaller motors results in other benefits, too – they require less materials to make, dropping the price, and they weigh less, which boosts power-to-weight in sportscar terms, but also load capacity on a heavy hauler. Mahle says the SCT motor concept is suitable for passenger cars, commercial vehicles, construction machines and tractors.

The current prototype SCT motors currently use neodymium magnets, but Mahle says the concept will play well with its magnet-free designs. We took a close look at Mahle's magnet-free motor innovations last year – they do away with rare earth metals and instead use contactless induction to induce precisely tuned electromagnetic fields in coils in the rotor. The company says they're cheap and highly efficient, and significantly, they don't rely on a supply chain that runs straight through China like nearly all rare earths. A magnet-free SCT motor would require "slightly more assembly space" than a neodymium version.

“Building large electric motors that deliver short-term high performance is easy," said Martin Berger, Vice President Corporate Research and Advanced Engineering at MAHLE, in a press release. "What was still lacking on the market until now were durable yet compact drives to make electric vehicles unrestricted for everyday use. Our new SCT E-motor is the solution.”

The SCT motor will be presented at IAA Transportation in Hanover this September and it'll take a while before we start seeing it in consumer EVs.

Check out a video below.

The MAHLE Superior Continuous Torque SCT E Motor

Source: Mahle

6 comments
6 comments
Larry W
Should be great for Semi trucks and any heavy load all the time applications like hauling freight up long grades on Interstates. Would also make a great motor to install on trailers themselves to do part or all of the work to extend the range of the towing vehicle of all kinds.
Karmudjun
Loz: Great article! Looks like Mahle has knocked it out of the park with this design. For H2 cell or battery power these tiny incremental improvements are huge!
I like that they can reduce the mass & materials required including rare earth magnets and therefore have lower environmental impact - but what of the cost to consumers? I'd like a high efficiency electric motor or two for conversion of my favorite vehicle - everything is economically prohibitive at the moment. As batteries pack more punch per kg or cm3 it is looking realistic - but economically it is looking dismal!
Chase
Hmm, based on the (admittedly low detail) design diagram I would think that at high RPM the motor might start to experience oil cavitation as the oil passes out of the spinning rotor and into the end housing. I wonder how that is addressed.
Slowburn Fan
Oil changes coming to future ev?
TechGazer
I wonder what the electrical efficiency of the non-PM version is, compared to the PM version. The ability to run at 90% full power is useful for some applications, but if the electrical efficiency is lower, a vehicle would be dumping more of its battery power out the radiator.
ljaques
Cool. What's the MTBF of the oil seals, and what will it cost to replace them on an EV? That would be the weak point on a very interesting motor design.