How to reduce the noise of DC motor?

The noise of different mechanical equipment may be large or small, but they should all have a normal scale specification value. When the specification value is exceeded, the equipment is likely to show a malfunction. What should we do if the DC motor is too noisy?


Motors are one of the sound sources that produce noise. Motors are widely used in household appliances, automobiles, office appliances, industrial, agricultural and medical industries, and are closely related to people’s lives. Therefore, it is the responsibility of every designer and producer to minimize the noise of the motor, produce a low-noise electric motor, and create a comfortable and quiet living environment for people.

There are many reasons for the vibration and noise of DC motors, which can be roughly attributed to mechanical noise, electromagnetic noise, and aerodynamic noise.


Analysis of noise produced by DC motor:

1. Bearing noise. Due to the improper size matching of the bearing and the bearing chamber, the DC motor will rotate with the DC motor rotor and generate noise. The out-of-roundness of the balls or the internal mixing of debris causes them to collide with each other to produce vibration and noise. The improper value of the pre-pressure of the bearing causes the raceway surface to vibrate slightly and generate noise.

2. Noise caused by an unbalanced rotor.

3. Noise caused by the eccentric assembly.

The following methods should be adopted to reduce the noise of DC motors:

1.Take care to avoid their resonance frequencies;

2.Use sinusoidal windings as much as possible to reduce harmonic components;

3.Use rotor skewed slots with one stator slot pitch;

4.The stator and rotor magnetic circuits are symmetrical and average, with tight overlap;

5.Choose suitable grooves together to prevent low-order force waves;

6.When machining and assembling stators and rotors, we should pay attention to their roundness and coaxiality;

7.Choose proper air gap magnetic density, which should not be too high, but Too low will affect the application rate of materials;

8.Generally, sealed bearings should be used to prevent debris from entering.

Use the de-weighting method or weighting method to correct the rotor dynamic unbalance; filling the buffer material between the magnetic steel and the Output shaft can absorb the tiny vibration generated by the rotor during the commutation process while avoiding the rigid connection of the Output shaft and the external load. The external vibration is transmitted to the magnetic steel, which affects the sudden change of Torque generated by the excitation. Prevent the resonance between the rotating frequency and the load from causing air noise.

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