The noise of the 3 phase motor including electromagnetic noise, mechanical noise and ventilation noise, the noise of electric motor, is basically the combination of a variety of noise, low noise requirements to achieve motor, we should comprehensive analysis the influencing factors of noise and take measures.
Parts processing precision control is a more effective measure, but there must be good equipment and technology to ensure that such measures can ensure the overall matching effect of motor parts; In addition, the mechanical noise of the motor can be effectively reduced by adopting low noise bearings; By adjusting the groove of stator and rotor and adjusting the slope of rotor groove, the electromagnetic noise of motor can be effectively reduced. The other is the adjustment measures of the motor wind path, many motor manufacturers take measures on the fan and wind hood of the motor to reasonably control the relationship between the motor noise, temperature rise and efficiency. Objectively speaking, the development needs of three phase motor products continue to put forward new topics to motor producers.
Electromagnetic noise is mainly caused by the periodic radial electromagnetic force or the unbalanced magnetic pull in the motor, which causes the core to magnetostriction and vibration. Electromagnetic noise is also related to the vibration characteristics of the stator and rotor itself. For example, when the exciting force resonates with the natural frequency, even if the electromagnetic force is very small, it will produce a lot of noise.
The suppression of electromagnetic noise can be done in many ways. For asynchronous motors, first of all, the appropriate number of stator and rotor slots must be selected. Generally speaking, the number of slots in the rotor and the number of slots in the stator is relatively different, that is, when the so-called far slot is matched, the electromagnetic noise is small. For the slotted motor, the slotted motor can make the radial force phase shift along the axis of the motor, so the axial mean radial force is reduced and the noise is reduced. If the double chute structure is used, the noise reduction effect is better. Double chute structure is along the axial rotor is divided into two sections. The skew direction of each slot is opposite. An intermediate ring is also arranged between the two segments.
In order to reduce the harmonic flux potential, double-layer short moment winding can be used. And avoid using fractional slot winding group. Sine winding should be adopted in the single phase motor. In order to reduce the electromagnetic noise caused by the tooth groove, the magnetic groove wedge can be used or the width of the fixed and rotor groove can be reduced until the closed groove is used. When the three-phase motor is running, the voltage should be maintained as symmetrical as possible, and the single-phase motor should run in a rotating magnetic field close to the circle. In addition, the motor manufacturing process, should reduce the stator and rotor outer ovality and guarantee, the rotor concentric, gets gap evenly. Reduce the air gap magnetic flux density and the larger air gap, can reduce the noise. In order to avoid the electromagnetic force and the natural frequency resonance of the housing, an appropriate elastic structure can be used.
