Tesla was first to patent a primitive axial-flux electrical motor—Nikola Tesla, that’s, manner again in 1889. It could be 126 years earlier than the idea discovered its technique to a automobile, the 1,500-horsepower (1,103 kilowatt), US $1.9 million, Koenigsegg Regera hybrid, in 2015. Even right this moment, practically all of the world’s EVs and hybrids depend on comparatively inefficient, easy-to-manufacture radial-flux motors.
But the newest electrified revolution is underway, led by YASA. Based within the U.Okay. by Tim Woolmer in 2009, a spin-off from his Oxford PhD venture, the corporate’s pioneering axial-flux motors are powering hybrid supercars from a Who’s Who of makers: Ferrari, Lamborghini, McLaren and Koenigsegg. These embrace the Ferrari 296 Speciale and Lamborghini Temerario that I lately drove in Italy.
Boosted by these power-dense electrical machines, these racy Italians carved up roads in Emilia-Romagna like hunks of prosciutto di Parma. The Temerario’s gasoline V-8 revs to a stratospheric 10,000 rpm, greater than any manufacturing supercar. Nonetheless not sufficient: The Temerario additionally integrates three YASA motors. A pair on the entrance axle ship all-wheel-drive traction and a peak 294 horsepower (216 kilowatts). A complete of 907 hybrid horsepower (667 kilowatts) sends the Temerario to a blistering 343 kph (213 mph) high pace. The electric motors ably fill any gaps in gasoline acceleration and finesse the dealing with with torque-vectoring , the electrified entrance wheels serving to to catapult the Lamborghini out of corners with ridiculous ease.
With their compact design and superior power-to-weight ratio, these motors are setting data on land, sea and air. The world’s fastest electric plane, the Rolls-Royce Spirit of Innovation, built-in three YASA motors for its propeller, sending it to a document 559.9 kph (345.4 mph) high pace. Making use of tech from its Formula E racing program, Jaguar used YASA motors to set a maritime electric speed document of 142.6 kph (88 mph) in England’s Lake District in 2018 (that document has since been damaged).
Claimed Power Density is Three Instances Tesla’s Greatest
In August, YASA’s motors helped the Mercedes-AMG GT XX prototype set dozens of EV endurance records. Cruising round Italy’s Nardo circuit at a sustained 186 mph (300 kph), the roughly 1,000-kilowatt (1,360 horsepower) Mercedes EV drove about 5,300 kilometers per day. In 7.5 days, it traveled 40,075 kilometers (24,902 miles), the precise equal of the earth’s circumference. That point included stops for charging, at 850 kilowatts.
Mercedes F1 driver George Russell stands subsequent to a Mercedes AMG GT XX throughout its record-setting endurance run this previous August. Powered by three YASA axial-flux motors, the idea EV drove the equal of the earth’s circumference in 7.5 days, at a near-steady 300 kph. A manufacturing model of the automobile may very well be a competitor for the Porsche Taycan. Mercedes-Benz
Mercedes purchased YASA outright in 2021. Daimler, Mercedes’ company guardian, is retrofitting a factory in Berlin to construct as much as 100,000 YASA motors a 12 months, for the subsequent logical step: The motors will energy mass-produced EVs for the primary time, particularly from AMG, Mercedes’ formidable high-performance division.
The corporate lately unveiled its newest motor, and its stats are eye-opening: The axial-flux prototype generates a peak 750 kilowatts, or 1,005 horsepower, as examined on a dynamometer. The motor can output a steady 350-400 kilowatts (469-536 horsepower). But the unit weighs simply 12.7 kilograms (27.9 kilos). Woolmer says the ensuing energy density of 59 kilowatts per kilogram is an unofficial world document for an electric motor, and about 3 times that of main radial-flux designs, together with Tesla’s.
“And this isn’t an idea on a display — it’s working, proper now, on the dynos,” Woolmer says. “We’ve constructed an electrical motor that’s considerably extra power-dense than something earlier than it, all with scalable supplies and processes.”
Simon Odling, YASA’s chief of latest know-how, walks me via the tech. Typical, radial-flux motors are formed like a sausage roll. A spinning rotor is housed inside a stationary stator. The traces of magnetic flux are oriented radially, perpendicular to the motor’s central shaft. These flux traces symbolize the interacting magnetic fields of the permanent magnets within the rotor and electromagnets within the stator. It’s that interplay that gives torque.
An axial flux design is extra like a pancake. In YASA’s configuration, a pair of much-larger rotors are positioned on both facet of the stator, and, notably, all three have roughly the identical diameter. Magnetic flux is oriented axially, parallel to the shaft. As a result of torque is proportional to the rotor diameter squared, an axial-flux design can generate considerably extra torque than a comparable radial-flux unit. The twin permanent-magnetic rotors double the important thing torque-generating elements, and guarantee a brief magnetic path, which reinforces effectivity by decreasing losses within the magnetic area.
YASA R&D Engineer Eddie Martin holds 12.7 kg axial-flux motor that cranks out 750 kilowatts/1,005 horsepower.YASA
Odling says the corporate’s motors are about one-third the mass and size of a comparable radial-flux machine, with intriguing upsides for automobile packaging and weight financial savings. “The motor sits between an engine and gearbox actually properly in a hybrid utility, or it makes for a really compact drive unit in an EV,” Odling says. The configuration can be supreme for in-wheel motors, as a result of the flat form matches simply inside the width of automobile and even motorcycle wheels.
YASA additionally touts the burden financial savings. Cascading good points in automobile structure may eradicate at the least 200 kilograms from right this moment’s EVs, the corporate says, about half from the motors themselves, the remainder from smaller batteries, brakes, and lighter-weight supporting buildings.
YASA’s Secret Sauce is a Gentle Magnetic Composite
The corporate’s title provides one other clue to its technical edge: YASA stands for “Yokeless and Segmented Structure.” The motors take away a heavy iron or metal yoke, the structural and magnetic spine for the copper coils in a traditional stator. As a substitute, they use a Soft Magnetic Composite (SMC)—a fabric that has very excessive magnetic permeability. That attribute means the fabric is a really efficient conductor of magnetic flux, so it may be used to pay attention and direct the sphere within the motor. In a typical utility, the stator’s coils are wrapped round buildings manufactured from SMC.
Woolmer started learning SMCs within the mid 2000s earlier than there have been potential paying clients for his nascent motor designs: The primary Tesla Roadster didn’t hit the highway till 2008, and suppliers and tooling for these motors didn’t exist then. Woolmer’s early axial-flux designs lastly made their manner into the Jaguar C-X75 in 2010, an idea that was cancelled previous to manufacturing. By 2019, Ferrari was integrating one among Woolmer’s motors in its first hybrid, the SF90.
SMC became a key innovation, as a result of axial-flux motors couldn’t be manufactured with the stacked-steel laminations of radial-flux machines. Woolmer segmented the stator into particular person “pole items” produced from SMC, which will be shaped underneath stress into an enormous number of 3D shapes. That flexibility significantly reduces weight and eddy-current losses, and lessens the cooling burden. The place a traditional motor might need 30 kilograms of iron, a comparable YASA design would want solely 5 kilograms to generate the identical energy and torque.
YASA’s stators additionally combine flat copper windings with direct oil cooling, Odling says, with no “buried copper” that the oil can’t attain. That significantly improves thermal efficiency and restoration in anxious circumstances, a possible boon for high-performance EVs.
YASA designs and develops its motors at its Oxford Innovation Heart. In Could, it opened a brand new axial-motor “tremendous manufacturing facility” in close by Yarnton, with capability for greater than 25,000 motors every year. The corporate additionally credit the British Advanced Propulsion Center (APC) as a linchpin of its growth. The collaboration between the U.Okay. authorities, business and academia seems to speed up homegrown growth of zero-emissionstransportation to satisfy Internet Zero targets.
YASA intends to launch extra specifics on its newest prototype motor in December. However firm executives say the motor is prepared for purchasers, with no unique supplies or manufacturing methods required.
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