Work is progressing on a new electric car motor concept that promises to extend the range of EVs without relying so much on larger batteries.
In December 2023, we looked at how German start-up Deepdrive and components supplier and tyre maker Continental were creating a revolutionary dual-rotor hub motor combined with an equally advanced ‘dry’ integrated electric drum brake.
BMW recently announced that it had been working with Deepdrive since 2021 through its venture client programme, BMW Startup Garage, and was poised to test the new tech.
The Deepdrive motor is a radial flux type. Normally that would mean it has a rotor either inside or outside of the stator, but in this case there are two rotors, one revolving inside the stator and the other outside it.
It’s one of those ideas that seems glaringly obvious, and although Deepdrive doesn’t claim that it’s a completely new concept, it does claim to be the first company to overcome the manufacturing difficulties associated with it.
It’s essentially two motors combined into one, resulting in stronger torque and greater torque density (this means the ratio of torque to the weight and size of the motor is greater than that of a conventional single-rotor motor design).
The tech is also claimed to be more efficient, because of the greater torque density and fewer system losses. It’s being developed both in central drive units for use in conventional EV drivetrains and as in-wheel motors.
Significantly, the new tech addresses a potential drawback of in-wheel motors: that of increased unsprung weight. Deepdrive says the lighter weight of the dual-rotor tech significantly reduces the problem.
Added to that, the high power density allows rear brakes to be reduced in size or even be rendered completely unnecessary. As a result, says Deepdrive, total unsprung masses aren’t necessarily increased compared with a regular front-wheel-drive car.
