The phrase “reinventing the wheel” is a typical admonishment for those who are recreating something that already has been developed and works pretty well. It is difficult to believe that someone could improve an invention so basic as the wheel, but from electric skateboards to robots to vehicles, we are starting to see the in-wheel motor as a building block for a new generation of moving things and people.
What makes the in-wheel design revolutionary is that electricity and a control bus replaces the mechanical methods of transferring energy from the source of power to the wheels. By eliminating things like transmissions and differentials, weight is removed and space is gained, freeing vehicle designers from the limitations of internal combustion engine and mechanical transmissions. The permanent magnet design results in further weight/size reduction and improved efficiency relative to AC-induction motors found in some electric cars (the potential downside being the availability of the rare-earth minerals needed for the permanent magnets)
As explained by Jose Bedolla, Protean has been refining the design of in-wheel motors for use in vehicles for a several years and is moving it into the mass-production realm with an opening of a factory in Tianjin, China. Part of their magic is that their wheel has been designed to be retrofitted into existing vehicles; either all-electric or hybrid vehicles, with four wheels collectively delivering over 400 horsepower.
Each in-wheel motor is self-contained with built-in inverter (8 for redundancy), control electronics and software. Integrated into the wheel is regenerative braking, which captures up to 85 percent of the available kinetic energy during braking. The ability to control each wheel independent of the others allows traction control, launch control and torque vectoring. According to Protrean, this results in “…far greater control, performance and vehicle dynamics than any other drive system.”
With the opening of its manufacturing facility, Protean looks to make this a volume product. Beyond their factories, they are open to licensing to others to build as well. And although there are few commercial announcements for in-wheel powered vehicles (e.g. Protean indicates Sonders Electric Car Company will integrate their wheels on their $10k vehicle), the activity by Protean and others, such as Elaphe, NSK and Yasa Motors, indicates that the wheel is on the verge of a reinvention.
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