Research on the Method of Improving the Voltage Withstand Capability of Variable-Frequency Drives Based on Improving Their Structure

Voltage sag sensitivity of the variable-frequency drives(VFD) is the main cause of power outage for electrical equipment, it is important to improve the voltage sag withstand capability of VFD. This paper proposed two schemes of structural modification on the VFD, that is, adjusting the value of DC side capacitor and adding a parallel auxiliary Boost circuit respectively. Two schemes were modeled in PSCAD and multiple scenarios were tested and analyzed. The results showed that both schemes had better voltage withstand capability in general, each scheme had its own advantages and disadvantages at all.