The future of electric vehicle performance isn’t about incremental improvements to existing motor technology; it’s a fundamental shift in design. While Tesla pioneered the initial concept of the axial-flux electric motor back in 1889, and Koenigsegg first integrated it into a production vehicle in 2015, it’s a British firm, YASA, that’s now leading a revolution in power density and efficiency. For decades, the automotive industry has relied on radial-flux motors, prioritizing ease of manufacturing over optimal performance. That’s changing, and quickly.
The Axial-Flux Advantage: A New Era of Electric Motors
Founded in 2009 as a spin-off from Oxford University research, YASA (Yokeless and Segmented Architecture) is rapidly becoming the go-to supplier for high-performance electric motors. Their innovative axial-flux design is already powering hybrid supercars from automotive royalty – Ferrari, Lamborghini, McLaren, and Koenigsegg – and is poised to disrupt the broader EV market. The company’s motors aren’t just finding their way into cars; they’re shattering speed records on land, sea, and in the air.
The Lamborghini Temerario, recently experienced firsthand in Italy, exemplifies this leap forward. Its V-8 engine, revving to a remarkable 10,000 rpm, is augmented by three YASA motors. Two motors drive the front axle, providing all-wheel-drive traction and an additional 294 horsepower (216 kilowatts). Combined, the hybrid powertrain delivers a staggering 907 horsepower (667 kilowatts), propelling the Temerario to a top speed of 343 kph (213 mph). The YASA motors seamlessly fill power gaps and enhance handling through precise torque-vectoring, making cornering an exhilarating experience.
Beyond the automotive realm, YASA’s technology is pushing boundaries. The Rolls-Royce Spirit of Innovation, the world’s fastest electric plane, utilized three YASA motors to achieve a record-breaking speed of 559.9 kph (345.4 mph). Similarly, Jaguar leveraged YASA motors to set a maritime electric speed record of 142.6 kph (88 mph) in 2018. More recently, in August, a Mercedes-AMG GT XX prototype, equipped with YASA motors, set dozens of EV endurance records at the Nardo circuit, completing the equivalent of Earth’s circumference in just 7.5 days.
Power Density: A Threefold Leap
YASA’s latest axial-flux prototype boasts a peak output of 750 kilowatts (1,005 horsepower) and a continuous output of 350-400 kilowatts (469-536 horsepower). Remarkably, this power is delivered from a unit weighing only 12.7 kilograms (27.9 pounds). According to YASA founder Tim Woolmer, this translates to a power density of 59 kilowatts per kilogram – an unofficial world record and approximately three times that of leading radial-flux designs, including those used by Tesla.
This isn’t merely a theoretical achievement. Woolmer emphasizes that these motors are fully functional and undergoing rigorous testing on dynamometers. The scalability of the materials and processes used in their construction further solidifies YASA’s position as a leader in electric motor technology.
How YASA’s Technology Works: Beyond the ‘Sausage Roll’
Conventional radial-flux motors, often described as resembling a “sausage roll,” feature a spinning rotor housed within a stationary stator. Magnetic flux lines radiate perpendicularly from the central shaft. YASA’s axial-flux design, in contrast, is more akin to a “pancake.” It utilizes a pair of larger rotors positioned on either side of the stator, all with roughly the same diameter. This configuration orients the magnetic flux axially, parallel to the shaft.
Because torque is proportional to the rotor diameter squared, axial-flux designs inherently generate more torque than comparable radial-flux units. YASA’s dual rotor setup doubles the torque-generating components and shortens the magnetic path, enhancing efficiency and minimizing energy loss. But the real innovation lies in YASA’s unique architecture.
The company’s name, YASA, stands for “Yokeless and Segmented Architecture.” Traditional motors rely on a heavy iron or steel yoke to provide structural support and guide the magnetic flux. YASA eliminates the yoke, replacing it with a Soft Magnetic Composite (SMC) – a material with exceptionally high magnetic permeability. This allows for a more efficient concentration and direction of the magnetic field. The segmented stator, constructed from individual SMC “pole pieces,” further reduces weight and eddy-current losses, simplifying the cooling process.
Simon Odling, YASA’s chief of new technology, explains that their motors are approximately one-third the mass and length of comparable radial-flux machines, offering significant advantages in vehicle packaging and weight reduction. “The motor sits between an engine and gearbox really nicely in a hybrid application, or it makes for a very compact drive unit in an EV,” Odling says. The flat shape also lends itself to in-wheel motor applications, fitting easily within the width of car and even motorcycle wheels.
These weight savings aren’t isolated; YASA estimates that cascading gains throughout the vehicle architecture could reduce overall EV weight by at least 200 kilograms, with half of that reduction stemming from the motors themselves, and the remainder from smaller batteries, brakes, and lighter supporting structures. What impact do you think these weight savings will have on the range and performance of future EVs?
Mercedes-Benz and the Future of YASA
In 2021, Mercedes-Benz acquired YASA outright. Daimler, Mercedes’ parent company, is currently retrofitting a factory in Berlin to produce up to 100,000 YASA motors annually. This investment signals a clear intention to integrate YASA’s technology into mass-produced EVs, starting with the high-performance AMG division.
YASA’s technology isn’t just about speed and power; it’s about efficiency and sustainability. The company’s commitment to scalable materials and processes ensures that these advancements can be readily implemented in large-scale manufacturing. How will this technology impact the accessibility of high-performance EVs to a wider consumer base?
With its groundbreaking axial-flux motor design and strategic partnership with Mercedes-Benz, YASA is poised to reshape the electric vehicle landscape. The company’s relentless pursuit of innovation is driving a new era of performance, efficiency, and sustainability in electric propulsion.
Frequently Asked Questions About YASA Motors
A: An axial-flux motor, like those produced by YASA, features rotors positioned on either side of the stator, with magnetic flux oriented axially (parallel to the shaft). This contrasts with radial-flux motors, where flux radiates perpendicularly from the shaft. Axial-flux designs generally offer higher torque density.
A: SMC is a material with high magnetic permeability, allowing it to efficiently conduct magnetic flux. YASA uses SMC in place of a traditional iron yoke, reducing weight and eddy-current losses, and improving overall efficiency.
A: YASA’s motors are currently used by several high-performance automakers, including Ferrari, Lamborghini, McLaren, Koenigsegg, and Mercedes-Benz.
A: YASA’s motors offer higher power density, lower weight, and improved efficiency compared to traditional radial-flux motors, resulting in enhanced acceleration, range, and handling for electric vehicles.
A: The compact, flat shape of YASA’s axial-flux motors makes them ideally suited for in-wheel motor applications, as they can easily fit within the limited space available inside a wheel.
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Disclaimer: This article provides information for general knowledge and informational purposes only, and does not constitute professional advice.
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