Wheel hub motor technology, also known as wheel-mounted motor technology, is characterized by the integration of power, transmission and braking devices into the hub, thus greatly simplifying the mechanical part of the electric vehicle. Wheel hub motor technology is not new. As early as 1900, electric vehicles with front wheel wheel motors were manufactured. In the 1970s, this technology was applied in mine transport vehicles and other fields. For the hub motors used in passenger cars, Japanese manufacturers have carried out earlier research and development of this technology and are currently in a leading position. International auto giants including General Motors and Toyota have also been involved in this technology.
The hub motor drive system is mainly divided into two types according to the rotor type of the motor: an inner rotor type and an outer rotor type. The outer rotor type adopts low-speed outer rotor motor, the maximum speed of the motor is 1000-1500r/min, no deceleration device, the rotation speed of the wheel is the same as that of the motor, and the inner rotor type adopts high-speed inner rotor motor and reducer with fixed transmission ratio. In order to achieve higher power density, the motor speed can be as high as 10000r/min. With the advent of more compact planetary gear reducers, the inner rotor hub motor is more competitive in terms of power density than the low speed outer rotor.