What are the solutions to the high noise of brushless motors that use semiconductor switching devices to achieve electronic commutation? Here is the editor's summary:
The noise reduction method of magnetic field angle can reduce the vibration and noise caused by axial permanent magnets, thereby reducing the magnetic induction noise of brushless motors. Brushless motors have main load magnetic potential and synchronous motor magnetic potential. In the arc range, the top armature reaction magnetic potential is larger.
Under the main load of the brushless motor, an asymmetric magnetic flux density is selected with a chamfered load tip, which causes the magnetic flux density at the main load tip to slowly expand and contract, weakening the relative magnetic potential of the synchronous motor and thus weakening the harmonic current electromagnetic field of the magnetic flux density. In addition, the brushless motor adopts a tilted viewing angle design scheme, which can greatly reduce the harmonic current amplitude of the magnetic induction torque.

In addition to magnetic induction noise, brushless motors also have mechanical equipment noise and natural ventilation noise. As mentioned earlier, their magnetic induction noise is generated by the harmonic current electromagnetic field and interaction of the motor rotor current on the magnetic density, which causes the vibration of the iron core magnetic yoke and drives the vibration of the surrounding gas. The key reason is that the slots are not properly matched, and the axial force or magnetic density of the motor rotor is too small. There are many types of mechanical noise, mainly caused by the manufacturing process and precision of brushless motors, as well as vibration noise or static balance caused by changes in backlash during the operation of rolling bearings.
The use of brushless motors provides assurance for equipment usage, with the advantages of high reliability, no commutation sparks, and low mechanical noise. I hope the above content is helpful to you.
Editor: Nancy