Direct Drive System to Make In-Wheel Electric Vehicles Closer to a Production Reality

This paper presents a compact, lightweight direct-drive system for the electric vehicle (EV) segment, which combines the motor, inverter, and brake into a single unit. This enables the entire system to be installed into the wheel and more expansive interiors and battery installation spaces, thus moving the world one step closer to a zero-emissions society. The new motor directly transmits the high driving force necessary to run an EV to the wheels, and its lightweight design and 2.5 kW/kg power density minimize the significant weight increase typically associated with in-wheel units. Moreover, implementing an in-wheel unit does not require a substantial change to the existing configuration of the suspension and other components. Driveshafts and other indirect mechanisms have been eliminated, enabling motor power to be applied directly to EV operation. This reduces energy loss by 30% and increases the range on a single charge compared with existing EVs.