Sophisticated electric motors will give some Alabama-built Mercedes and Ferrari electric cars an edge

When drivers of future Mercedes-AMG models – including those built in Alabama – hit the accelerator of their electric cars, they’ll get the added oomph of batteries from something that looks straight out of “back to the future.”

No, not flux capacitors, but axial flow motors.

Mercedes-Benz AG and Ferrari NV are turning to this type of electric motor to generate headrest torque. Axial flow motors are much smaller than the often used radial motors, but have more powerful power.

Bloomberg: The engine technology that powers Mercedes’ high-performance Ferrari EVs in the electric age from Alabama NewsCenter on Vimeo.

All Mercedes cars produced at Mercedes-Benz American International in Alabama are available in high-performance AMG versions. They include the GLE Coupe, GLE SUV, GLS SUV and Mercedes-Maybach GLS SUV. The plant also produces the electric EQS ​​SUV and will add the EQE SUV.

Sophisticated engines like these will be critical to brands like AMG and Ferrari as they race to electrify high-performance cars that earn prestige and plentiful profits. All electric vehicles offer a sense of instant acceleration, from the Nissan Leaf to the Tesla Model S Plaid. Whereas in the era of combustion faster off-line times and higher speeds have been achieved with more engine cylinders, manufacturers will differentiate performance electric vehicles by getting the most out of batteries with lighter, more efficient engines.

“The power-to-weight ratio is really a record, much better than conventional engines,” said Markus Schaefer, Mercedes’ chief technology officer, of the company’s upcoming AMG electric platform. “It would benefit from the small size of the engine.”

Koenigsegg Regera hybrid supercar. (Ron Antonelli/Bloomberg)

With each press of the accelerator, electric vehicle drivers push hundreds – and in some cases thousands – of amperes of electric current into copper coils. When these coils are energized, they become electromagnets with attractive and repulsive forces. The magnetic force generated by the stator stator surrounding the rotor rotor produces a torque that turns the wheels of the vehicle.

In axial motors, instead of rotating the rotor inside the stator, the disk-shaped rotors rotate along with the central stator. This causes the current – the flow – to travel axially through the machine, rather than out radially from the center. Since the motor generates torque with a larger diameter, less material is required. Yasa, the Oxford, England-based engine manufacturer used in the plug-in hybrids in the Ferrari SF90 and 296 GTB, uses just a few kilograms of iron in its stator, reducing the machines’ mass by up to 85%.

Yasa motors are the brainchild of Tim Woolmer, whose work in them was the focus of his PhD in electrical engineering at Oxford University. Within a few years of earning his doctorate, Jaguar Land Rover made plans to use Yasa engines in the C-X75, a two-seater hybrid electric car with enough horsepower to rival the Porsche 918 Spyder, McLaren P1 and Ferrari LaFerrari. While JLR ended up canceling the project due to financial constraints, Yasa engines found their way into the Koenigsegg Regera hybrid, followed by the Ferrari SF90.

In July last year, Mercedes announced that it had acquired Yasa for an undisclosed amount and would put its engines in AMG models slated for launch from 2025.

“If you look at the history of cars in general, car companies want to have the engine, and its core technology, inside the company,” Woolmer said in an interview. “Batteries, motors, that’s their core technology now. They understand the importance of having long-term differentiation in these spaces, so they have to bring it within the company.”

The most important aspect of hub drives is the form factor capabilities, according to Malte Jaensch, professor of sustainable mobile drives at the TUM School of Engineering and Design in Munich. Its smaller size may allow automakers to place one motor on each wheel, which is not possible with radial motors.

Putting a motor on each wheel — or at least one motor on each axle — can translate to horrific EV driving performance. The innovation allows for torque vectoring that better controls the amount of power the motors send to each individual wheel to improve agility. High-speed cornering may help AMG and Ferrari drivers overcome the lost roar of their eight, 10 or 12 cylinder engines.

Walmer said Yasa engines can also completely eliminate the need for a powertrain on the so-called skateboard down the middle of an electric car. This will open up more space for engineers to pack the batteries, make room for more front and rear trunk space, or allow designers to experiment with new aerodynamic ideas.

The Mercedes AMG Edition 55 GLE SUV is built in Alabama. It is possible that future versions of the car will have a special engine designed for electric and hybrid vehicles. (Mercedes AMG)

The small size and light weight of hub motors will not only benefit high performance cars. They’re also finding a home in aerospace, which led Yasa to roll out its electric aviation division Evolito last year. The world’s fastest electric vehicle, Rolls-Royce Plc electric aircraft called the Spirit of Innovation, uses three axial flow motors to drive the propeller. The plane can travel about 380 miles (612 kilometers) per hour, making it faster than the Spitfire fighter jet that was powered by a Rolls-Royce V12 engine.

“The important thing is its efficiency,” said Matthew Barr, Rolls-Royce’s Spirit of Innovation project leader. “This allows you to keep the weight of the aircraft low.”

Axial motors will not necessarily be the death knell for radial motors, which provide higher top speeds. This led to Ferrari using two radial motors on the front axle for the SF90, along with a hub motor on the rear axle. For the 296 GTB, handling was more important, so only a lighter coaxial motor was used between the engine and transmission.

“It’s just a matter of what kind of driving experience you want to design for your customers with a specific engine,” said David Ferrara, Ferrari’s director of electric motors. “Different sounds give beautiful notes.”

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