System and device for exporting power, and method of configuring thereof

Abstract

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.

Claims

1. A system comprising: a plurality of inverting devices connected in series, wherein each of the plurality of inverting devices is configured to be connected with a plurality of power sources, and wherein at least one of the plurality of inverting devices comprises a plurality of dc/dc converters comprising a plurality of buck converter blocks and a shared output filter; and a system controller having inputs connected to the plurality of inverting devices, and outputs configured to be connected to a power grid, wherein the system controller comprises a plurality of switches.

2. The system of claim 1, wherein: each of the plurality of inverting devices is configured to perform independent maximum power point tracking (MPPT) for a corresponding power source of the plurality of power sources.

3. The system of claim 1, wherein: at least one of the plurality of power sources is a photovoltaic (PV) module.

4. The system of claim 1, wherein: at least one of the plurality of power sources is a PV sub-module cell string.

5. The system of claim 1, wherein the at least one of the plurality of inverting devices comprises: the plurality of dc/dc converters connected in series, wherein each of the plurality of dc/dc converters is connected to a corresponding power source; and an inverter having inputs connected to outputs of the plurality of dc/dc converters connected in series.

6. The system of claim 5, wherein: each of the plurality of buck converter blocks comprises two switches connected in series; and the shared output filter is connected to a common node of the two switches.

7. A system comprising: a plurality of inverting devices connected in series, wherein each of the plurality of inverting devices is configured to be connected with a plurality of power sources, and wherein at least one of the plurality of inverting devices comprises a plurality of dc/dc converters comprising a plurality of buck converter blocks and a shared output filter; and a system controller having inputs connected to the plurality of inverting devices, and outputs configured to be connected to a power grid.

8. The system of claim 7, wherein: the system controller comprises a plurality of switches.

9. The system of claim 7, wherein: the shared output filter is connected to a common node of the two switches of one of the plurality of buck converter blocks.

10. The system of claim 7, wherein: one of the plurality of inverting devices comprises a full-bridge inverter.

11. An inverter system comprising: a plurality of inverting devices connected in series, wherein each of the plurality of inverting devices is configured to be connected with a plurality of power sources, and at least one of the plurality of inverting devices comprises: a plurality of dc/dc converters, each of which is connected to a corresponding power source; an inverter having inputs connected to outputs of the plurality of dc/dc converters; and a shared output filter shared by the plurality of dc/dc converters; and a system controller having inputs connected to the plurality of inverting devices, and outputs configured to be connected to a power grid.

12. The inverter system of claim 11, wherein: the system controller comprises a plurality of switches configured to control power flowing from the plurality of inverting devices and the power grid.

13. The inverter system of claim 11, wherein: the plurality of power sources, the plurality of dc/dc converters and the inverter are connected in cascade.

14. The inverter system of claim 13, wherein: one power source of the plurality of power sources is a PV module; one dc/dc converter of the plurality of dc/dc converters is a non-isolated converter; and the inverter is a full-bridge inverter.

15. The inverter system of claim 11, wherein: the shared output filter is an LC filter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other exemplary features, aspects and advantages of the disclosure will become more apparent from the following detailed description of illustrative embodiments thereof when taken in conjunction with the accompanying drawings in which:

(2) FIG. 1 illustrates an example of a conventional microinverter architecture.

(3) FIG. 2 illustrates an example of a conventional AC optimizer architecture.

(4) FIG. 3 illustrates an example of multi-input AC optimizer (MILVAC) architecture according to illustrative embodiments of disclosure.

(5) FIG. 4A illustrates an example of AC optimizer (MILVAC) architecture application with multiple PV module inputs according to illustrative embodiments of disclosure.

(6) FIG. 4B illustrates an example of AC optimizer (MILVAC) architecture application with multiple PV sub-module cell string inputs according to illustrative embodiments of disclosure.

(7) FIG. 5A illustrates an example of AC optimizer (MILVAC) internal configuration according to illustrative embodiments of disclosure.

(8) FIG. 5B illustrates an example of AC optimizer (MILVAC) internal configuration according to illustrative embodiments of disclosure.

(9) FIG. 6A illustrates an example of DC/DC converter topology according to illustrative embodiments of disclosure.

(10) FIG. 6B illustrates an example of DC/DC converter topology according to illustrative embodiments of disclosure.

(11) FIG. 6C illustrates an example of DC/DC converter topology according to illustrative embodiments of disclosure.

(12) FIG. 7A illustrates an example of inverter topology according to illustrative embodiments of disclosure.

(13) FIG. 7B illustrates an example of inverter topology according to illustrative embodiments of disclosure.

(14) FIG. 8 illustrates an example of AC optimizer (MILVAC) internal configuration according to illustrative embodiments of disclosure.

(15) FIG. 9 illustrates an example of AC optimizer (MILVAC) internal configuration according to illustrative embodiments of disclosure.

(16) FIG. 10 illustrates in a process diagram an example of configuring a system including multi-input AC optimizer (MILVAC) architecture according to illustrative embodiments of disclosure.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(17) This description is provided to assist with a comprehensive understanding of illustrative embodiments with reference to the accompanying drawing figures. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the illustrative embodiments described herein can be made within the scope of appended claims without departing from their full scope and equivalents. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness. Likewise, certain naming conventions, labels and terms as used in the context of the present disclosure are non-limiting and provided only for illustrative purposes to facilitate understanding of exemplary implementations of the illustrative embodiments.

(18) Generally, illustrative embodiments disclose system and method including multiple distributed, optionally low voltage, multi-input AC optimizers (MILVACs or devices) each having multiple DC inputs each connected with its DC source, and a circuit, including hardware and/or software components for performing independent MPPT to extract essentially maximum power from its DC source and generate AC voltage at an AC output of the AC optimizer (MILVAC or device). The AC outputs of the multiple AC optimizers can be connected in series before coupling to a system controller, or ultimately to an AC grid. Benefits resulting from such systems and methods include, for example and without limitation, cost savings compared to single one-to-one input AC optimizer architecture due to use of less AC connectors, reduction in AC filter size afforded by a multi-level topology, and cost reduction in parts whose costs do not scale proportionally with power, such as enclosure, sensing and controller circuitry, gate drivers, relays. Another exemplary non-limiting benefit is higher efficiency due to a more flexible topology choice, especially multi-level topology that reduces AC filter size.

(19) According to illustrative embodiments of the disclosure, in a distributed system, each AC optimizer (MILVAC or device) has multiple DC inputs and each DC input can be connected to a DC source and provided with an independent MPPT function. This can result in significant cost saving. Referring to FIG. 3, each of MILVACs 100-1 to 100-N has multiple DC inputs: MILVAC 100-1 has multiple inputs 103-1-1, 103-1-2, . . . 103-1-N each connected to a respective one of DC sources 10-1-1, 10-1-2, . . . 10-1-N; MILVAC 100-2 has multiple inputs 103-2-1, 103-2-2, . . . 103-2-N each connected to a respective one of DC sources 10-2-1, 10-2-2, . . . 10-2-N; and so on as diagrammatically illustrated by a MILVAC 100-N with multiple inputs 103-N-1, 103-N-2, . . . 103-N-N each connected to a respective one of DC sources 10-N-1, 10-N-2, . . . 10-N-N. Each MILVAC 100-1 to 100-N extracts power from the respective DC sources connected thereto, and outputs an AC voltage at its AC output: MILVAC 100-1 has an AC output 104-1; MILVAC 100-2 has an AC output 104-2; and so on to MILVAC 100-N with an AC output 104-N. The outputs 104-1 to 104-N of MILVACS 100-1 to 100-N are connected in series as input to system controller 180, which is connected to grid 90.

(20) In an illustrative embodiment, as diagrammatically shown in a non-limiting example of FIG. 4A, each DC input of any, one or more, or all of AC optimizers, such as MILVAC 100-1 to 100-N, can be connected to a respective one of individual PV modules 110-N-1, 110-N-2, . . . 110-N-N, for example in a manner of DC sources as illustrated in non-limiting example of FIG. 3. In yet another illustrative embodiment, as diagrammatically shown in a non-limiting example of FIG. 4B, each DC input of any, one or more, or all of AC optimizers, such as MILVAC 100-1 to 100-N, can be connected to a respective one of individual PV sub-module cell strings (also referenced, without any limitation, as “PV cell strings”) 120-N-1, 120-N-2, . . . 120-N-N, for example in a manner of DC sources as illustrated in non-limiting example of FIG. 3, each of the PV cell strings 120-N-1, 120-N-2 comprising one or more PV cells 200. Each of the multiple DC inputs 103-N-1, 103-N-2, . . . 103-N-N can be used as an independent MPPT channel for each of the PV cell strings. This can result in significant cost saving.

(21) According to illustrative embodiments, different internal configurations of any one or more, or all, of AC optimizers, such as any MILVAC 100-N, or any one or more, or all, of MILVACs 100-1 to 100-N, which can perform the function of receiving multiple DC inputs and providing an optimized AC output based thereon, are within the scope of the disclosure. In an illustrative embodiment, as diagrammatically shown in a non-limiting example of FIG. 5A, each DC input 103-N-1, 103-N-2, . . . 103-N-N of a MILVAC is coupled with an input of a respective one of DC/DC converters 150-N-1, 150-N-2, . . . 150-N-N, and the respective outputs 153-N-1, 153-N-2, . . . 153-N-N, of all the DC/DC converters 150-N-1, 150-N-2, . . . 150-N-N, are connected in series 170-N before coupling to the input 106-N of an inverter 160-N connected to, or providing, output 104-N of the MILVAC. In another illustrative embodiment, as diagrammatically shown in a non-limiting example of FIG. 5B, each DC input 103-N-1, 103-N-2, . . . 103-N-N of a MILVAC is coupled with an input of a respective DC/DC converter 150-N-1, 150-N-2, . . . 150-N-N, and the respective outputs 153-N-1, 153-N-2, . . . 153-N-N, of all the DC/DC converters 150-N-1, 150-N-2, . . . 150-N-N, are connected in parallel 180-N before coupling to the input 106-N of an inverter 160-N connected to, or providing, output 104-N of the MILVAC.

(22) According to illustrative embodiments, different DC/DC converter topologies, which can perform the function of receiving one or multiple DC inputs and DC/DC conversion, as part of internal configurations of any one or more, or all, of AC optimizers, such as any MILVAC 100-N, or any one or more, or all, of MILVACs 100-1 to 100-N, of a system, are within the scope of the disclosure. In an illustrative embodiment, as diagrammatically shown in a non-limiting example of FIG. 6A, a boost convert (or step-up converter, or a DC-to-DC power converter, whose function is to step up voltage, while stepping down current, from its input to its output) can perform DC/DC conversion function as a DC/DC converter 250-N-N, comprising exemplary circuit components, including an inductor 254-N-N, switches 255-N-N and 256-N-N, and capacitors 252-N-N and 259-N-N, configured as shown in the circuit diagram, receiving DC input 103-N-N and providing DC output 253-N-N. In an exemplary implementation, switch 256-N-N of converter 250-N-N can be a diode. In another illustrative embodiment, as diagrammatically shown in a non-limiting example of FIG. 6B, a combination buck-boost converter (or a type of DC-to-DC converter that function to have an output voltage magnitude that is either greater than or less than the input voltage magnitude) can perform DC/DC conversion function as a DC/DC converter 350-N-N, comprising exemplary circuit components, including an inductor 354-N-N, switches 355-N-N, 356-N-N, 357-N-N, and 358-N-N, and capacitors 352-N-N and 359-N-N, configured as shown in the circuit diagram, receiving DC input 103-N-N and providing DC output 353-N-N. In an exemplary implementation, any one of, or both, switches 356-N-N and 357-N-N of converter 350-N-N can be a diode.

(23) In yet another illustrative embodiment, another DC/DC converter topology, which can perform the function of receiving multiple DC inputs and DC/DC conversion, as part of internal configurations of any one or more, or all, of AC optimizers, such as any MILVAC 100-N, or any one or more, or all, of MILVACs 100-1 to 100-N, of a system, can include multiple DC/DC converters connected in a series DC/DC configuration where the converters can share a filter, such as an LC filter, before providing input to an inverter. This minimizes the filter size. As shown in a non-limiting example of FIG. 6C, multiple DC/DC converters 450-N-1, 450-N-2, . . . 450-N-N, such as buck converters (or step-down converts, or a DC-to-DC power converter, whose function is to step down voltage, while stepping up current, from its input to its output), comprising respective exemplary circuit components, including switches 455-N-1, 455-N-2, 455-N-N, and 456-N-1, 456-N-2, 456-N-N, and capacitors 452-N-1, 452-N-2, and 452-N-N, configured as shown in the circuit diagram, receiving respective DC inputs 103-N-1, 103-N-2, . . . 103-N-N, can be connected in a series DC/DC configuration to share a filter, such as an LC filter comprising an inductor 480-N and a capacitor 490-N, and providing input 106-N to inverter 160-N.

(24) According to illustrative embodiments, different inverter topologies, which can perform the function of receiving output of any of the DC/DC converters of any of the topologies described herein, as part of internal configurations of any one or more, or all, of AC optimizers, such as any MILVAC 100-N, or any one or more, or all, of MILVACs 100-1 to 100-N, of a system, are within the scope of the disclosure. In an illustrative embodiment, as shown in a non-limiting example of FIG. 7A, a full bridge inverter can perform DC/AC inverter function as an inverter 260-N, comprising exemplary circuit components, including an inductor 754-N, switches 755-N, 756-N, 757-N, and 758-N, and capacitors 752-N and 759-N, configured as shown in the circuit diagram, receiving DC input 106-N and providing AC output 104-N. In another illustrative embodiment, as shown in a non-limiting example of FIG. 7B, a diode neutral point clamped three-level half-bridge inverter can perform DC/AC inverter function as an inverter 360-N, comprising exemplary circuit components, including an inductor 364-N, switches 365-N, 366-N, 367-N, and 368-N, capacitors 361-N, 362-N and 363-N, and diodes 369-N and 370-N configured as shown in the circuit diagram, receiving DC input 106-N and providing AC output 104-N.

(25) According to further illustrative embodiments, another internal configuration of any one or more, or all, of AC optimizers, such as any MILVAC 100-N, or any one or more, or all, of MILVACs 100-1 to 100-N, which can perform the function of receiving multiple DC inputs and providing an optimized AC output based thereon, couples each DC input with an input of an inverter (without an AC filter), all the inverters are then cascaded, followed by an AC filter. In an illustrative embodiment, shown in a non-limiting example of FIG. 8, multiple inverters 460-N-1, 460-N-2, . . . 460-N-N receiving respective DC inputs 103-N-1, 103-N-2, . . . 103-N-N, can be connected in a series configuration to share an LC filter comprising an inductor 580-N and a capacitor 590-N, providing AC output 104-N. In an exemplary implementation, any one or more, or all of inverters 460-N-1, 460-N-2, . . . 460-N-N can comprise a full bridge inverter 500 comprising exemplary circuit components, including switches 565-N, 566-N, 567-N, and 568-N and a capacitor 569-N configured as shown in the circuit diagram.

(26) In another illustrative embodiment, yet another internal configuration of any one or more, or all, of AC optimizers, such as any MILVAC 100-N, or any one or more, or all, of MILVACs 100-1 to 100-N, which can perform the function of receiving multiple DC inputs and providing an optimized AC output based thereon, provides a DC/DC converter between each inverter and its DC input, all the inverters are then cascaded, followed by an AC filter. In an illustrative embodiment, shown in a non-limiting example of FIG. 9, multiple inverters 560-N-1, 560-N-2, . . . 560-N-N receive respective DC inputs 106-N-1, 106-N-2, . . . 106-N-N from respective DC/DC converters 550-N-1, 550-N-2, . . . 550-N-N connected to respective DC inputs 103-N-1, 103-N-2, . . . 103-N-N. Multiple inverters 560-N-1, 560-N-2, . . . 560-N-N are then connected in a series configuration to share an LC filter comprising an inductor 680-N and a capacitor 690-N, providing AC output 104-N.

(27) The cascaded inverters form a multi-level inverter, which results in reduced AC filter size.

(28) According to yet another illustrative embodiment of the disclosure, a method of configuring a system for exporting power comprises connecting one or more AC optimizers (MILVAC or device), each with multiple DC inputs and optionally having structure and functionality in accordance with any aspects of previously-disclosed illustrative embodiments, to individual DC sources and perform independent MPPT function to extract power from each DC source, and couple the extracted power to a power grid. Referring to example of FIG. 10: in step S901, each of multiple inputs 103-1-1 to 103-N-N of one or more AC optimizers 100-1 to 100-N is connected to respective DC sources 10-1-1 to 10-N-N; in step S902, power is extracted from the respective DC sources 10-1-1 to 10-N-N by respective AC optimizer s100-1 to 100-N, each of which performs independent MPPT to extract power form its DC sources and outputs an AC voltage at its AC output 104-1 to 104-N; in step S903, the outputs 104-1 to 104-N of AC optimizers 100-1 to 100-N are combined (optionally, by connection in series); optionally, in step S904, combined outputs of AC optimizers 100-1 to 100-N are provided as input to system controller 180; and in step S905, the combined outputs of AC optimizers 100-1 to 100-N are coupled to grid 90.

(29) The above-presented description and figures are intended by way of example only and are not intended to limit the illustrative embodiments in any way except as set forth in the appended claims. It is particularly noted that various technical aspects of the various elements of the various exemplary embodiments that have been described above can be combined in numerous other ways, all of which are considered to be within the scope of the disclosure.

(30) Accordingly, although exemplary embodiments have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions, and substitutions are possible. Therefore, the disclosure is not limited to the above-described embodiments, but may be modified within the scope of appended claims, along with their full scope of equivalents.