DOUBLE CONVERSION ON LINE UPS WITH PASS THROUGH NEUTRAL EMPLOYING SINGLE DC BUS

An Uninterruptible Power Supply (UPS) system, the UPS system comprising an input configured to receive input AC power having an input voltage level and an input frequency, an output configured to provide output AC power to a load, the output power having an output voltage level and an output frequency, a converter coupled to the input and configured to convert the input AC power into DC power, an inverter coupled to the output and configured to convert the DC power into the output AC power and provide the output AC power to the output, a DC bus coupled between the converter and the inverter including a first capacitive element and a second capacitive element, the first capacitive element being coupled to a first output and a second output of the converter and the second capacitive element being coupled to a first input and a second input of the inverter, a de-coupler circuit coupled between the first and second capacitive elements and configured to selectively decouple the inverter from the converter, and a controller configured to operate the converter, the inverter, and the de-coupler circuit in a first mode of operation such that the output voltage level and output frequency of the output AC power are the same as the input voltage level and input frequency of the input AC power and a second mode of operation such that at least one of the output voltage level or output frequency of the output AC power differs from the input voltage level and input frequency of the input AC power.