The rotor is one of the very important parts of the motor ,stepper motor , BLDC motor and sp on. The outer rotor and the inner rotor are two common rotor types in the field of motors. According to the position of the rotor, DC motors can be divided into inner rotor motors and outer rotor motors. In an external rotor motor, the rotor is located on the outside (outside the motor) and the stator is located inside the motor. In contrast, in an internal-rotor motor, the rotor is located inside the motor and the stator is located outside the motor. You may want to ask: What's the difference between them?

The inner rotor is the transmission part of the motor, and the outer motor shell is static. The outer rotor is the motor housing that rotates, and the inner part is fixed and does not rotate.

The differences between internal rotor motors and external rotor motors are as follows:

1. Different rotation positions: the inner rotor motor rotates internally, the main shaft of the rotor motor rotates together, the motor base is fixed, the outer shell is used as the stator, and the inner rotor and the main shaft are used as the rotor. The external rotor motor rotates externally. In an external rotor motor, the rotor rotates together with the motor casing, the main shaft of the motor is fixed, the casing serves as the rotor, and the interior and the main shaft serve as the stator.

2. Different speeds: In brushless DC motors, the speed of the inner rotor motor is significantly higher than that of the outer rotor motor. The inner rotor generally has fewer poles, higher rotational speed, and smaller torque; the outer rotor generally has more poles, lower rotational speed, and larger torque.

3. The rotational inertia of the outer rotor motor is greater than the rotational inertia of the inner rotor: when the weight of the rotor is the same, the rotational inertia of the inner rotation is not as large as that of the outer rotation, so the kv of the inner rotation is high and the torque is low; the rotational inertia of the outer rotation is large, This improves the efficiency and output power of the motor under unstable loads.

4. The inner rotor is the static part design on the inside of the working rotating part of the motor, and the outer rotor is designed on the outside of the motor rotating part. It uses a DC permanent magnet brushed iron motor, which is energy-saving, efficient and has extremely high speed.

5. Different application fields: Inner rotors are often used in power machinery such as motors, generators, gas turbines, compressors, etc., while outer rotor motors can be used in different situations according to their characteristics, such as low speed and high torque, direct drive, and constant speed. , and other occasions where small changes in rotational speed are required. Motors with outer rotors dissipate heat better.

6. Different maintenance difficulties: External rotor motors are easy to maintain and have better heat dissipation. Inner-rotor motors are more difficult to repair and repair, and the internal coils are difficult to wind. If the internal rotating motor is burned out, you cannot wind the enameled wire yourself.