Increasing immunity of variable frequency drives against power quality issues

Abstract

A system for increasing immunity against power quality problems includes a battery bank configured to supply an uninterruptible power supply (UPS) with direct current (DC) power and a variable frequency drive (VFD). The VFD includes a DC bus with a DC bus voltage, a VFD inverter configured to invert the DC bus voltage to an AC VFD output voltage of a desired frequency, and a rectifier configured to convert an alternating current (AC) supply voltage to the DC bus voltage, and supply the DC bus with the DC bus voltage. The system further includes an electrical connection between the battery bank and the DC bus, the electrical connection configured to provide a supplemental DC current from the battery bank when a DC current provided by the DC bus fails to match a DC current demand by the VFD inverter.

Dependencies are inferred from the claim text.