Technology

The YASA™ Motor

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 (20Nm/kg which is typically at least 2 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 500Nm YASA™ motor has been developed specifically for electric and hybrid vehicles.  The motors are compact (34cm in diameter and 7cm wide), and fit within the space of the front or rear differential of a typical vehicle (the differential is no longer required). The motors output 500Nm per 'slice', with a peak power of around 75kW. This means 2 motor slices are enough for most vehicles. For example the Westfield iRacer uses two motor mounted at the rear of the vehicle and is targeting a sub 6s 0-60 time. 

YASA™ motor videos

Motor bench test - two 500Nm YASA™ motors are tested back-to-back to provide performance data of the motors. The motors are run over a series of drive cycles to test the efficiency and thermal performance of the motors. 

Below is the Westfield iRacer. The vehicle uses two 500Nm YASA™ Motors mounted in rear of the vehicle. The video shows the car at a 'drifting' event. 

News article on the Riversimple Urban Car which is powered by four prototype wheel motors using YASA™ technology.

More information on the Riversimple Urban Car.