The Yokeless And Segmented Armature (YASA™) topology is a new type of axial flux motor that shows a step change improvement in torque density when compared to other axial flux motors. The topology is based around a series of magnetically separated segments that form the stator of the machine. The step change in the specific torque of the motor (30-40Nm/kg which is typically at least 2-4 times better than the best alternatives) comes from the combination of patented improvements in the magnetics, the cooling and the packaging of the motor.
The YASA-750 has been developed specifically for electric and hybrid vehicles. This direct drive motor is compact (350mm in diameter and 70mm wide), and fit within the space of the front or rear differential of a typical vehicle (the differential is no longer required). The motors have had independent dynanometer testing and a peak torque of 750Nm (for 1 min) and a continuous torque of 400Nm. With a peak power of up to 100kW (at 400V), and a continuous power of >50kW 2 motor 'slices' are enough for most sports vehicles. An example application is the Westfield iRacer which uses two motors mounted at the rear of the vehicle and accelerates from 0-60 in less than 5s. A number of customers are also using 4 motors to give racing performance with 400kW of traction available.
The video below shows Robert Llewellyn visiting YASA motors and talking to their CTO (Dr. Tim Woolmer) about the technology.
An example application of the YASA motor is on the Westfield iRacer. The vehicle uses two YASA-750 motors mounted in rear of the vehicle. The video shows the car at a 'drifting' event.
Another example application of the YASA-750 motor is in the Delta E4 coupe. The vehicle uses two of these Motors. The video below show Robert Llewellyn taking a test drive in the vehicle.