System and device for exporting power, and method of configuring thereof
System, device and method for exporting power are provided including at least one AC optimizer with plurality of DC inputs each connecting with respective one of plurality of DC sources, and independent maximum power point tracking (MPPT) performed for each respective DC source to extract power from each DC source for output and coupling to AC grid. When multiple AC optimizers are employed, with each AC optimizer having multiple DC inputs, each DC input can be connected to PV module with independent MPPT function. Since, each AC optimizer can serve multiple PV modules, significant cost saving and efficiencies can be achieved. Optionally, on PV sub-module level, each of the multiple DC inputs can be used as an independent MPPT channel for a PV sub-module cell string.
1. A distributed DC to AC system comprising:
a plurality of DC sources;
a first AC optimizer comprising a plurality of first DC inputs, a plurality of DC/DC converters and a first AC output, each of said first DC inputs connected to a respective one of said plurality of DC sources through one of the plurality of DC/DC converters, wherein the first AC optimizer comprises a filter shared by series-connected outputs of the plurality of DC/DC converters;
a second AC optimizer comprising a plurality of second DC inputs and a second AC output, each of said second DC inputs connected to a respective one of said plurality of DC sources; and
a system controller receiving input from said first AC optimizer and second AC optimizer, and controlling the first AC output and the second AC output to provide power to an AC grid, wherein each of said first AC optimizer and said second AC optimizer is a multiple-input single-out optimizer, and the first AC output and the second AC output are connected in series and further connected to the AC grid through the system controller.
2. The system of claim 1 , wherein
said plurality of DC sources comprises a plurality of first DC sources and a plurality of second DC sources, and wherein the plurality of first DC sources is connected to the first AC optimizer and the plurality of second DC sources is connected to the second AC optimizer.
3. The system of claim 1 , wherein at least one of said plurality of DC sources comprises a PV module.
4. The system of claim 1 , wherein at least one of said plurality of DC sources comprises a PV sub-module cell string.
5. The system of claim 1 , wherein the plurality of DC/DC converters of said first AC optimizer comprises:
a first DC/DC converter comprising a first DC/DC input and a first DC/DC output, at least one of said first DC inputs of said first AC optimizer is coupled with said first DC/DC input;
a second DC/DC converter comprising a second DC/DC input and a second DC/DC output, at least another of said first DC inputs of said first AC optimizer is coupled with said second DC/DC input; and
an inverter comprising an inverter input coupled to said first DC/DC output and said second DC/DC output.
6. The system of claim 5 , wherein said first DC/DC output and said second DC/DC output are connected in series before coupling to said inverter input.
7. The system of claim 5 , wherein said first DC/DC output and said second DC/DC output are connected in parallel before coupling to said inverter input.
8. The system of claim 5 , wherein
said first AC optimizer further comprises the filter,
said first DC/DC converter is a first step-down DC-to-DC converter,
said second DC/DC converter is a second step-down DC-to-DC converter, and
said first DC/DC output and said second DC/DC output are connected in series to share said filter before coupling to said inverter input.
9. A method for configuring a system comprising:
connecting a plurality of first DC sources to a first AC optimizer comprising a plurality of first DC inputs and a first AC output, each of said first DC inputs being connected to a respective one of said first DC sources, wherein the first AC optimizer comprises a first DC/DC converter between a first DC input and the first AC output, a second DC/DC converter between a second DC input and the first AC output, a filter, and an inverter, and wherein the first DC/DC converter and the second DC/DC converter are connected in series to share the filter before coupled to an input of the inverter;
through a circuit, performing independent maximum power point tracking (MPPT) for each of said respective first DC sources connected to said first DC inputs;
connecting a plurality of second DC sources to a second AC optimizer comprising a plurality of second DC inputs and a second AC output, each of said second DC inputs being connected to a respective one of said second DC sources;
through the circuit, performing independent maximum power point tracking (MPPT) for each of said respective second DC sources connected to said second DC inputs to extract power from each of said second DC sources; and
coupling optimized AC power from said first AC optimizer and said second AC optimizer connected in series to an AC grid through a system controller, wherein each of said first AC optimizer and said second AC optimizer is a multiple-input single-output optimizer, and the system controller includes two switches.
10. The method of claim 9 , wherein at least one of said plurality of first and second DC sources comprises a PV module.
11. The method of claim 9 , wherein at least one of said plurality of first and second DC sources comprises a PV sub-module cell string.
12. An AC optimizer comprising:
a plurality of DC inputs, each of said DC inputs connecting to one DC source of a plurality of DC sources,
a circuit performing independent maximum power point tracking (MPPT) for each of said DC sources connected to said DC inputs to extract power from each of said DC sources and generate an AC voltage; and
an AC output outputting said AC voltage,
wherein said circuit further comprises:
a filter;
a first step-down DC/DC converter comprising a first DC/DC input and a first DC/DC output, at least one of said DC inputs coupled with said first DC/DC input;
a second step-down DC/DC converter comprising a second DC/DC input and a second DC/DC output, at least another of said DC inputs coupled with said second DC/DC input; and
an inverter comprising an inverter input coupled to said first DC/DC output and said second DC/DC output, and an inverter output connected to said AC output, and
wherein said first DC/DC output and said second DC/DC output are connected in series to share said filter before coupling to said inverter input.
13. The AC optimizer of claim 12 , wherein said plurality of DC sources comprises a plurality of PV modules.
14. The AC optimizer of claim 12 , wherein said plurality of DC sources comprises a plurality of PV sub-module cell strings.
15. The AC optimizer of claim 12 , wherein said filter is an LC filter.
16. The AC optimizer of claim 12 , wherein the AC optimizer is connected to an AC grid through a system controller.
17. The AC optimizer of claim 12 , wherein the inverter is a full bridge inverter.