The manufacturer reminds that the source of motor noise is vibration. The basic reason for electromagnetic noise is that the electromagnetic force causes the motor iron core and iron core teeth to vibrate, that is, the electromagnetic field changes and causes some machine parts to vibrate, which causes the space atmosphere to oscillate. The resulting atmospheric pressure wave is similar to the sound of a certain reliable frequency domain when a tuning fork is activated.
Common causes of electromagnetic noise in high-power motors include large open space between the coil and the iron core, loose coils, improper carrier frequency configuration during variable frequency power supply, magnetic saturation, and so on.
How to use the company to intuitively appreciate electromagnetic noise?
If your variable frequency motor has a piercing high frequency sound when it is energized, and it disappears immediately after the power is off, it can be considered that the electromagnetic force is infiltrated into the conductive or permeable magnet to make it vibrate, and then cause the surrounding atmosphere to pulsate and generate electromagnetic noise.When the motor is running, there is a fundamental wave magnetic field and a harmonic wave magnetic field in the air gap. When these magnetic fields generate tangential electromagnetic torque, a radial force that changes with time and space will also occur. These radial forces are separated in the stator and rotor. On the iron core, and make it produce radial deformation, that is, vibration.For the competition, the rigidity of the rotor core is large, so the amount of vibration that occurs is small, so the vibration of the stator core and the frame should be emphasized and considered.
There are many factors that affect the electromagnetic vibration of the stator sector, such as the factors of the winding itself, the result of the dipping of the winding, and the common stator and rotor slots.To deal with the electromagnetic noise problem of the motor, the process control of the production and manufacturing process is of course important, but the most important thing is the choice of design parameters. Reasonable slot common, reasonable slot slope, and appropriate air gap length adjustment are all for electromagnetic noise competition. Effective essentials.
Slot inclination is the degree of staggered angle between the stator and rotor slots. Skewing either the stator or the rotor is a feasible and effective solution.How to choose and control it? In view of the hard wire embedding in the stator slanted slot, electrical obstacles such as turn-to-turn, ground, and phase-to-phase are easily generated, and there are many constraints on the production and processing of skewed stator cores. Generally, straight slots are recycled in the stator sector. The rotor department recycling chute.In the actual production and processing process, the chute process is realized in the process of superimposing the shaft and the rotor core. If the method is not correct, it is easy to lead to poor consistency of the slot slope, and the most direct effect is probably electromagnetic noise.Even though the chute process better guarantees the design value, the chute parameters themselves are not fair. At this time, not only will the electromagnetic noise be eliminated or weakened, the electromagnetic noise may be larger or even the noise test value may be higher than the scale limit.
