In-wheel motor technology is also known as wheel-mounted motor technology. Its biggest feature is the integration of power, transmission and braking devices into the wheel hub, thus greatly simplifying the mechanical parts of electric vehicles. In-wheel motor technology is not a new thing. As early as 1900, electric vehicles equipped with in-wheel motors on the front wheels were manufactured. In the 1970s, this technology was applied in fields such as mine trucks.
As for the in-wheel motors used in passenger cars, Japanese manufacturers have carried out research and development of this technology earlier and are currently in a leading position. International automobile giants including General Motors and Toyota have also set foot in this technology.
The in-wheel motor drive system is mainly divided into two structural types according to the rotor type of the motor: inner rotor type and outer rotor type. The outer rotor type uses a low-speed outer rotor motor, the maximum speed of the motor is 1000-1500r/min, and there is no deceleration device, and the wheel speed is the same as the motor; while the inner rotor type uses a high-speed inner rotor motor with a fixed transmission ratio reducer , In order to obtain higher power density, the speed of the motor can be as high as 10000r/min. With the emergence of more compact planetary gear reducers, the inner-rotor hub motor is more competitive than the low-speed outer-rotor type in terms of power density.