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Blog Do You Know About Mid-drive Motors and Hub Motor? Why Are So Many Hub Motors Used in Electric Bicycles? Maintenance Methods of Hub Motor

What Are the Classifications of Hub Motors?

In-wheel motor technology is also known as in-wheel motor technology. Its biggest feature is that power, transmission and braking devices are integrated into the wheel hub, thus greatly simplifying the mechanical part of electric vehicles.

1. Understand the in-wheel motor

To know the relative position of the rotor and stator before starting the brushless hub motor, a sensor must be used. The non-inductive motor directly measures the back electromotive force of the motor to know the position of the rotor, and the controller drives the power tube to commutate. Although the memory can record the relative positions of the stator and rotor, it will not be able to understand the waveform of the back EMF of the motor windings for very slow rotating systems. When the motor reaches a certain speed, due to inertia restrictions, the peaks and valleys represent a certain angle, and the motor is turned off when braking.

The hub motor is a motor installed on the rear wheel of the electric vehicle and the wheel. It usually adopts a brushless motor. The hub motor has a simple structure and is usually composed of a coil, a rotating shaft, a magnet and a shell. Under the action of the current, the positive and negative The pole magnetic steel sheet generates a huge current magnetic field, and driven by the current, the middle shaft rotates rapidly. Due to the simple structure, the failure rate of the in-wheel motor is relatively low, and the kinetic energy conversion rate of the in-wheel motor is currently about 80%.

2. Classification of in-wheel motors

There are two types of hub motors: geared hub motors and gearless hub motors.

Geared hub motors were limited by precision and materials in the early days, and frictional force was generated due to insufficient precision, resulting in problems such as noise and wear. With the development of industrial technology, most geared hub motors are now very well made, so you don't have to worry about this. Moreover, when the electric vehicle is powered off or the battery is dead, there is a clutch device designed inside the geared hub motor, so that the resistance of the vehicle when it is coasting or manually stepped on is smaller than that of the gearless hub motor under the same conditions. Therefore, it is widely used by electric vehicle manufacturers.

The internal structure of the gearless hub motor is relatively traditional, there is no replica planetary reduction device, and it directly relies on electromagnetic conversion to generate mechanical energy to drive the electric vehicle. The gearless hub motor adopts a direct drive type, which generally does not have a clutch device inside, so it is necessary to overcome electromagnetic resistance when the power is off, but because of this, the hub motor of this structure can convert kinetic energy when going downhill. Stored in batteries for electrical energy. In fact, not all gearless hub motors can recover kinetic energy, and although this sounds like a very good idea, it is very expensive to use in practice, and it will increase its complexity.