An uninterruptible power supply (UPS) system includes first and second busses, a first switching circuit configured to selectively couple an AC source to the first and second busses and a second switching circuit configured to selectively couple the first and second busses to a load. The system also includes a storage capacitor and a third switching circuit configured to couple the storage capacitor between the first and second busses. The system further includes a control circuit configured to control the first, second and third switching circuits to generate an AC voltage at the load.