FUEL CELL BASED UNINTERRUPTIBLE POWER SUPPLY SYSTEMS

A system includes a DC bus and an auxiliary power source coupled to the DC bus. The system further includes an energy storage device and a modular uninterruptible power supply (UPS) including a first uninterruptible power module (UPM) coupled to the DC bus and configured to provide power to an AC load from the auxiliary power source and a second UPM coupled to the DC bus and the energy storage device and configured to transfer energy between the DC bus and the energy storage device to regulate a voltage on the DC bus.