When designing the structure again, it is mainly consid […]
When designing the structure again, it is mainly considering the influence of the 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 grade, generally F grade or higher, to strengthen the insulation strength of the ground and the insulation of the coil, especially the ability of the insulation to withstand the impact voltage.
2) For the vibration and noise of the motor, the rigidity of the motor component and the whole should be fully considered, and the natural frequency should be increased as much as possible to avoid resonance with each force wave.
3) Cooling method: Generally, forced air cooling is adopted, that is, the main motor cooling fan is driven by an independent motor.
4) Measures to prevent shaft current. For bearings with a capacity exceeding 160 kW, bearing insulation measures should be adopted. 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.