One of the fundamental requirements Protean imposed on its in-wheel motor design from the outset was to completely remove any mechanical gearing from the motor, along with all the required bearings, lubricants and seals for such a device. This was done for several reasons:
A direct-drive motor will have a lower mass than a high-speed motor with gear. However, the route Protean took was to accept this mass increase for the above reasons and conduct research into the real-world effects that unsprung mass has on the ride and handling of a given vehicle.
All parts of the system have been assessed for safety implications and are being developed to appropriate safety standards.
Key activities for the analysis include:
- Ensure compliance with regulations and standards
- Ensure systems are certifiably safe
- Ensure processes are effective and conformant
- Perform required safety analyses
- Refine the motor design
Key regulations and standards include:
- UNECE (UN/EU)
- 13/13H : Braking
- 100: Battery electric vehicles
- Federal Motor Vehicle Regulations (United States)
- 105 Hydraulic and electric brake systems
- Various standards, guidelines and test procedures
- Automotive specific version of IEC61508
- Automotive SPICE
- Process and maturity model
- Safety analysis, C and Simulink coding guidelines.
A key requirement that drove Protean’s motor design was the ability to be retrofit on existing vehicles. Designing any technology into a vehicle development cycle creates lead times of 3 to 5 years. But global OEMs need to significantly increase the fuel economy of and remove significant amounts of carbon emissions from their entire fleet right now. A handful of niche vehicles will not achieve these mandates. The ability to engineer a hybrid or full EV on an existing platform, with minimal tear-up of existing hardware or intrusion into passenger, storage or accident-vulnerable space cannot be underestimated and is one of the main advantages of choosing an in-wheel motor to propel a vehicle. It is therefore highly desirable for an in-wheel motor to be able to be fitted to a car without requiring any special wheel design or requiring risky suspension modifications, and this played a large part in the development of the requirements for the Protean motor.