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Causes and solutions of motor electromagnetic noise

Date:2023-08-23   Author:XINDA MOTOR
The main reason for the electromagnetic noise generated by the motor is the harmonic component, especially those harmonics whose frequency is relatively close to the base frequency. These harmonics may cause resonance and cause excessive vibration and generate a lot of noise.

Choose a reasonable air gap, because the asynchronous motor needs to absorb reactive current from the grid to establish an excitation magnetic field, so the air gap of the asynchronous motor should not be too large, otherwise the power of the motor will be reduced. However, it should not be too small. If it is too small, it will increase the difficulty of manufacturing, and the unilateral magnetic pull caused by insufficient concentricity of the stator and rotor may cause the shaft to deform and cause the stator and rotor to rub iron.

Increase the number of slots, but this will increase the amount of copper material and insulating material used in the motor, that is, increase the cost of the motor. Generally, in order to eliminate tooth harmonics, asynchronous motors generally use rotor chute. Synchronous motors use stator skew slots because the rotor is extremely inconvenient, usually with a stator pitch.

Magnetic slot wedges are generally not used in small and medium motors. In the actual production process, the main method of reducing noise for small and medium-sized motors is to choose the appropriate slot fit and select the appropriate air gap and chute. In addition, the processing accuracy and assembly of the mechanical structure will have a great impact on the noise of the motor.

First, the method of reducing electromagnetic noise of asynchronous motor

(1) Reasonable selection of air gap flux density.

(2) Select the appropriate winding form and the number of parallel branches

(3) Increase the number of stator slots to reduce the harmonic distribution coefficient

(4) Appropriate groove fit

(5) Using magnetic slot wedges

(6) Rotor chute

2. The electromagnetic noise of the products that have been produced is relatively large

(1) Appropriately increase the moment of inertia of the base section to avoid the resonance zone;

(2) The synchronous saliency machine can increase or decrease the width of the pole piece properly to improve the magnetic field distribution through calculation, so that the fundamental wave is closer to the sine wave, thereby reducing the high-order harmonic component and achieving the effect of reducing electromagnetic noise;

(3) Choosing a more appropriate stator winding wiring rotation number can effectively reduce the reverse wave generated by the motor winding, thereby reducing noise;

(4) For gears with high harmonic content, magnetic slot shoes can be used.

3. Newly designed motor

(1) Select the appropriate number of grooves to cooperate;

(2) Select the appropriate pole distance;

(3) Increase the number of parallel branches;

(4) For the salient pole machine, select the appropriate pole piece width;

(5) In the case of guaranteed motor performance, properly reduce the air gap magnetic density;

(6) The concentricity of the stator and rotor is guaranteed through the process, so that the unilateral magnetic pull tends to zero.