Things You Must Know About Hub Motors

The hub motor is a motor installed inside the wheel, and its main feature is to integrate power, transmission, and braking devices into the hub, thereby greatly simplifying the mechanical parts of electric vehicles.

Introduction to Hub Motor

In addition to different design styles and types, many components of the hub are the same, mainly composed of rims and spokes. In addition, there are many parameters included in all hubs, such as rim level, weight level, hole spacing, offset, width, and so on. For traditional vehicles, the clutch, gearbox, driveshaft, differential, and even transfer case are essential, making the vehicle's structure more complex and also requiring regular maintenance and addressing issues of failure rates. The appearance of hub motors is basically the same, mostly flat, but there are significant differences in motor types, structural forms, and driving methods. Currently, there are four main types of motors used in electric hub motors, namely permanent magnet motors (PM), asynchronous motors (IM), switched reluctance motors (SRM), and transverse flux motors (TFM). Among these four types of motors, permanent magnet motors are the most commonly used, while transverse flux motors are a highly competitive type of low-speed, high-torque new motor.

Hub motors can be divided into high-speed and low-speed, but there is no clear definition of the corresponding speed range, usually depending on the application. Typically, only when the driving mode is determined does the definition of high and low speed ranges have a relatively accurate meaning, that is, direct drive generally corresponds to low-speed motors (large volume, more materials, low power density, low noise), while indirect drive mostly corresponds to high-speed motors (small volume, fewer materials, high power density, high noise).

Speed control methods of hub motors

2) Frequency modulation; Frequency modulation (FM) is another method of controlling the speed of the hub motor. In FM, the pulse width remains constant, but the pulse frequency can vary. This means that the motor receives pulses of higher or lower frequencies, thereby changing the motor's speed. 3) Current limiting control method: Current limiting control is a method of controlling the speed of a hub motor by limiting the amount of current sent to the motor. In this method, the current sent to the motor can be controlled by changing the width and frequency of the pulses.

Application prospects of hub motors

At present, two-wheel hub technology is relatively mature. It is expected that as global energy and environmental issues become increasingly prominent in the future, high-quality hub motors used in electric vehicles will become an important research direction in the field of electrical engineering. At present, the demand for new energy vehicles in the global market has increased to a certain extent, and it is expected that there will be greater room for improvement in the future with the advancement of technology.