An uninterruptible power supply (UPS) system includes an AC input configured to be coupled to an AC power source, an AC output configured to be coupled to a load and a power converter circuit coupled to the AC input and the AC output and configured to selectively provide power to the load from the AC power source and an auxiliary power source. The UPS system further includes a control circuit operatively coupled to the power converter circuit and configured to generate at least one galvanically isolated neutral reference from the AC power source and/or from the AC output and to control the power converter circuit responsive to the generated at least one neutral reference. In particular, the control circuit may be configured to generate the neutral reference from a three-wire AC connection.