Machinery simplified knowledge about ebike motor
Posted by Jayson shawn on
It is made up of stator core, magnetic steel rotor, sun wheel, decelerating clutch, Wheel hub shell and so on.
A Hall sensor can be mounted on the top of the motor cover for speed measurement.
There are three types of position sensors: magnetic sensing, photoelectric and electromagnetic.
A brushless DC motor with magnetic-sensitive position sensor is adopt, whose magnetic sensor components (such as hall element, magnetic-sensing diode, magnetic-sensing epipolar tubes, magnetic-sensing resistor, or special integrated circuit, etc.) are installed on the stator assembly to detect changes in magnetic field caused by permanent magnet and rotor rotation.
1, Stator core
Effect: A part of a magnetic circuit on which stator windings are placed.
Structure: The stator core is usually made of silicon steel sheets with insulating layer on the surface of 0.35-0.5 mm thick. There are uniformly distributed slots punched in the inner circle of the core to embed the stator windings.
The stator core groove has the following kinds:
Half closed slot: The efficiency and power factor of the motor are high, but the winding, inlay and insulation are difficult. It is commonly used in small low-voltage motors.
Half open slot: The formed winding can be embedded, generally used in large and medium-sized low-voltage motors. The so-called formed winding is that the winding can be insulated before putting into the groove.
Open slot: It is used to embed the forming winding. The method of insulation is convenient, mainly used in high voltage motor.
2.Stator winding
Structure: It consists of three winding connected to each other with the same structure, which are in the space between 120 ° / 60 °, and symmetrically arranged. The coils of these windings are respectively embedded in each groove of the stator according to certain rules..
There are three main insulation projects for stator windings: (ensuring reliable insulation between the conductive parts of the winding and the core and reliable insulation between the windings themselves).
(1) Insulation to the ground: Insulation between stator winding and stator core.
(2) Interphase insulation: Insulation between stator windings of each phase.
(3) Inter turn insulation: The insulation between the turns of each stator winding.
3.Clutch
Which is assembly by nylon gears,single rotation clutch.This part is used for 2 purpose.
1) increase the torque,with high RPM speed combine with 5:1 reduction ratio,the high rpm turn to high torque.Also lower the high current Amp to decrease heat inside of motor.
2) When you don't pedel and push the bike,there is no resistance with the help of clutch.The direct drive motor,however,it has obvious resistance when you push the bike and it turns to a generator.
Advantages
It has advantages of long life, free maintenance and high reliability.
High efficiency and energy saving. Generally speaking, the efficiency of BLDCM is usually higher than 85% because it has no mechanical commutation friction loss, gear box loss and speed control circuit loss. However, considering the highest cost performance ratio in practical design, the design is generally 76% to reduce material consumption.
An video of handmade winding process.