What are inner rotor motors and outer rotor motors?
Inner rotor: The main shaft of the motor turns, the electric housing is fixed, and the permanent magnet is in the center.
Outer rotor: Refers to a motor with a rotating casing and a fixed shaft, with permanent magnets in the middle and outer rings.
Although the outer rotor motor and the inner rotor motor look the same, the actual function is different.
1. The difference between the inner rotor and the outer rotor lies in their rotation position, one rotates inward and the other rotates outward;
2. The outer rotor motor is easy to maintain and has better heat dissipation, but the maintenance of the inner rotor motor is more difficult;
3. The moment of inertia of the outer rotor motor is greater than that of the inner rotor motor, which has the characteristics of high torque and low torque, while the outer rotor motor is just the opposite;
4. The inner rotor is often used in power machinery, such as electric motors, generators, gas turbines, compressors, etc., while the outer rotor is usually installed in the impeller, which has a good cooling effect.
5. The inner rotor generally has few poles, high speed and small torque, and has high requirements on the strength of the permanent magnet ring. Especially for high-speed motors, when it is above 50,000rpm, it will be considered to add a protective steel sleeve outside the permanent magnet to prevent centrifugal force from affecting the permanent magnet during high-speed rotation. Damage caused by magnets; the outer rotor generally has a large number of poles, low speed, high torque, and moderate strength requirements for permanent magnets.
6. The speed is different. Among the brushless DC motors, the speed of the inner rotor motor is significantly higher than that of the outer rotor motor, so the high-speed motors of vacuum cleaners or blowers seen on the market are all inner rotor motors. This kind of motor will have relatively high requirements on the machining accuracy and physical properties of the permanent magnet.
7. The inner rotor is the design of the inner static part of the working part of the motor, and the outer rotor is the design of the outer part of the motor part. The DC permanent magnet brushed iron motor is used, which is energy-saving, efficient and has a particularly high speed.
