Patent ID: 8664796

Claim:
An uninterruptible power supply (UPS) comprising: a plurality of electrical buses; a first AC/DC converter coupled to the electrical buses and configured to receive a first input AC voltage and to convert the first input AC voltage to a plurality of DC voltages, the first AC/DC converter being configured to convey the plurality of DC voltages to the plurality of electrical buses; a second AC/DC converter coupled to the electrical buses and configured to receive a second input AC voltage and to convert the second input AC voltage to the plurality of DC voltages, the second AC/DC converter being configured to convey the plurality of DC voltages to the plurality of electrical buses; a third AC/DC converter coupled to the electrical buses and configured to receive a third input AC voltage and to convert the third input AC voltage to the plurality of DC voltages, the third AC/DC converter being configured to convey the plurality of DC voltages to the plurality of electrical buses; a first DC/AC converter coupled to the plurality of electrical buses and configured to receive the plurality of DC voltages and to convert the plurality of DC voltages into a first output AC voltage; and a DC bus balancer configured to maintain voltages present on the electrical buses at desired levels, the DC bus balancer being configured to transfer energy between the plurality of electrical buses.