A new in-wheel motor for electric vehicles (EVs) delivers a massive amount of torque in a lightweight package, its developers say.
The motor — which was made by YASA, a subsidiary of Mercedes-Benz that also provides motors to Ferrari — weighs only 28 pounds (12.7 kilograms) but can deliver up to 1,000 horsepower at once or a sustained 469 to 536 hp for longer durations. This new mark breaks YASA’s own previous unofficial record, a 29-pound motor that yielded 738 horsepower, company representatives said in a statement.
The ability to pack so much power into such a compact, lightweight motor is due in part to YASA’s axial flux technology. Traditional radial flux motors are longer, tube-like structures, with a stator — the stationary part of a motor that creates a magnetic field used to produce motion — surrounding a cylindrical rotor. A magnetic field is passed perpendicularly to the shaft through the cylinder to spin the rotor.
By contrast, an axial flux motor is more like a pancake, with a disc-like rotor and stator. Magnetic flux passes along the axis parallel to the shaft (hence the name). The axial flux tech allows for much smaller designs than traditional radial designs, according to YASA.
Much lighter EVs in the future
The company emphasized that the design is scalable and doesn’t rely on any rare or exotic materials to function.
The design also opens up a pathway for massive weight reduction in EV design. YASA said that deploying the in-wheel motors in lieu of a traditional power and drivetrain could save around 440 pounds (200 kg). And for vehicles designed from the ground up to incorporate the new motor, the savings could be closer to 1,100 pounds (500 kg).
This is in part because the system also incorporates advanced regenerative braking, the process by which electric vehicles capture energy that would normally be lost as heat during braking and utilize it to recharge the battery.
Instead of power being shunted from the battery to spin the wheels, energy from the wheels is captured to spin the motor, which generates electricity rather than consuming it. The motor resists the rotation while generating energy, thereby slowing the car and powering up the battery. YASA says efficient regenerative braking could reduce the need for traditional friction brakes, saving both weight and space.
While the current iteration is clearly geared toward high-performance EVs and supercars, axial flux motor technology opens the door for longer-range electric vehicles capable of generating more power with fewer, lighter components. The reduction in space required for traditional powertrain components also provides manufacturers an opportunity to streamline aerodynamics or provide more interior space for cargo or passengers.
