In the process of structural design of the variable frequency motor fan, it is necessary to consider the influence of its non-sinusoidal power supply characteristics on the insulation structure, vibration and noise cooling mode of the variable frequency motor. Generally pay attention to the following problems.
1. Insulation class: The inverter motor fan is generally F grade or higher when used. It strengthens the insulation strength of the ground insulation and the wire, especially the ability of the insulation to withstand the impact voltage.
2. Inverter motor fan vibration and noise problems in the use of the motor, to a certain extent, need to fully consider the motor mechanism and the overall rigidity, try to improve its natural frequency, avoiding resonance with each force wave.
3. The cooling method of the inverter motor fan is mainly forced air cooling when it is used, that is, the main motor cooling fan is driven by a very independent motor.
4. Measures to prevent shaft current. Bearing insulation measures should be adopted for motors with a capacity exceeding 160 kW. Mainly due to the asymmetry of the magnetic circuit, the shaft current is also generated. When the currents generated by other high-frequency components work together, the shaft current will increase greatly, resulting in bearing damage, so insulation measures are generally taken.
5. For constant power variable frequency motor, when the speed exceeds 3000r/min, special high temperature resistant grease should be used to compensate for the temperature rise of the bearing.