Uninterruptible power supply systems and methods supporting load balancing
An uninterruptible power supply (UPS) system that includes a multiphase AC output configured to be coupled to a load, an inverter having an output coupled to the AC output and a control circuit operatively associated with the inverter and configured to cause the inverter to compensate for a phase imbalance of a load coupled to the AC output while power is being delivered to the load from an AC power source independently of the inverter.
1. An uninterruptible power supply (UPS) system, comprising:
an AC input configured to be coupled to an AC power source;
a multiphase AC output configured to be coupled to a load;
a rectifier configured to receive power from the AC input;
an inverter having an output coupled to the AC output;
a DC link coupling an output of the rectifier to an input of the inverter;
a bypass circuit configured to selectively couple and decouple the AC input and the AC output; and
a control circuit configured to cause the inverter to load a first phase at the AC output and transfer power to a second phase at the AC output to compensate for phase imbalance of a load coupled to the AC output when the AC input is coupled to the AC input by the bypass circuit.
2. The UPS system of claim 1 , wherein the DC link is coupled to an auxiliary power source.
3. The UPS system of claim 2 , wherein the auxiliary power source comprises a variably available power source and/or a battery.
4. The UPS system of claim 3 , wherein the variably available power source comprises a wind power source and/or a solar power source.
5. The UPS system of claim 1 , wherein the inverter comprises a DC input configured to receive power from an auxiliary power source and wherein the control circuit is configured to cause the inverter to selectively transfer power between the auxiliary power source and the AC output to compensate for the phase imbalance.
6. The UPS system of claim 5 , wherein the auxiliary power source comprises a variably available power source and/or a battery.
7. The UPS system of claim 6 , wherein the variably available power source comprises a wind power source and/or a solar power source.
8. A UPS system, comprising:
an AC input configured to be coupled to an AC power source;
an AC output configured to be coupled to a load;
a rectifier configured to receive power from the AC input;
an inverter having an output coupled to the AC output;
a DC link coupling an output of the rectifier to an input of the inverter;
an interface circuit coupled to the DC link and configured to be coupled to a variably available power source;
a bypass circuit configured to selectively couple and decouple the AC input and the AC output; and
a control circuit operatively coupled to the rectifier, the inverter, the bypass circuit and the interface circuit and configured to cause the inverter to use the variably available power source to compensate for phase imbalance of a load coupled to the AC output when the AC input is coupled to the AC input by the bypass circuit.
9. The system of claim 8 , wherein the interface circuit is configured to be coupled to a wind power source and/or a solar power source.
10. The system of claim 9 , further comprising a battery interface circuit coupled to the DC link and configured to be coupled to a battery.