Vibration and noise are important performance indicators of motor products, and vibration and noise are two accompanying physical phenomena. There are three main types of motor noise, namely electromagnetic noise, mechanical noise, and ventilation noise.
Electromagnetic noise is directly related to whether the power is on, that is, the electromagnetic noise will stop immediately after the power is turned off, which is different from mechanical noise and ventilation noise. When solving the electromagnetic noise of the motor, specific measures can be taken, such as selecting the matching of the stator and rotor slots, adjusting the air gap between the stator and the rotor, using inclined slots for the stator or rotor, and avoiding specific power frequencies. As well as special technical measures such as radial coupling of stator and rotor flux. In the process of selecting an electromagnetic solution, it is likely that other performance indicators (such as torque) will be reduced to meet lower electromagnetic noise. This is a compromise process made in accordance with the priority guarantee of motor applications. However, in the actual application of motors, such as motors for electric vehicles, low noise and high torque are often required at the same time, which is a difficult problem that motor technology must overcome.
In the control of mechanical noise, the focus is on the optimization of the bearing system. Under the condition that the load is satisfied, bearings with relatively low noise should be selected to ensure the rationality of the working clearance of the bearing system. This requires scientific cooperation between tolerance selection and high-precision parts, that is, the processing consistency and roughness of parts must reach a high quality level.
In the control of ventilation noise, the design of the motor air path is very important, especially for high-speed motors. Whether it is a self-fan-cooled structure or a forced-ventilated structure, it is a very challenging task. In order to solve the problem of ventilation noise, some motors use liquid cooling structure instead of ventilation structure, or effectively combine the two to solve the conflicting relationship between ventilation noise and motor temperature rise to the greatest extent.
Due to the different application places of motors, the noise control requirements for new energy vehicle motors and motors operating in relatively concentrated environments are very strict, and corresponding performance improvement measures must be followed up in a timely manner.