Parallel connected inverters

• US 10,644,589 B2
• Filed: 04/20/2018
• Issued: 05/05/2020
• Est. Priority Date: 12/05/2007
• Status: Active Grant

• Current Assignee: Solaredge Technologies Incorporated
• Original Assignee: Solaredge Technologies Incorporated
• Inventors: Adest, Meir, Sella, Guy, Handelsman, Lior, Galin, Yoav, Fishelov, Amir, Gazit, Meir, Glovinski, Tzachi, Binder, Yaron
• Primary Examiner(s): Berhane, Adolf D
• Application Number:
  US15/958,129
• Publication Number:
  US 20190097531A1
• Time in Patent Office: 746 Days
• Field of Search: 363 65, 363 71, 363 72
• CPC Class Codes: G01S 3/7861 Solar tracking systems
• CPC Class Codes: H02J 13/00 Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources maximum power point systems in particular G05F1/67
• CPC Class Codes: H02J 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/388 Islanding, i.e. disconnection of local power supply from the network
• CPC Class Codes: H02J 3/46 Controlling of the sharing of output between the generators, converters, or transformers
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/0077 Plural converter units whose outputs are connected in series
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H02M 1/44 Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
• CPC Class Codes: H02M 3/04 by static converters
• CPC Class Codes: H02M 7/44 by static converters
• CPC Class Codes: H02M 7/493 the static converters being arranged for operation in parallel
• CPC Class Codes: H02S 40/22 Light-reflecting or light-concentrating means directly associated with the PV cell or integrated with the PV cell H01L31/054
• CPC Class Codes: Y02E 10/52 PV systems with concentrators
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A distributed power system wherein a plurality of power converters are connected in parallel and share the power conversion load according to a prescribed function, but each power converter autonomously determines its share of power conversion. Each power converter operates according to its own power conversion formula/function, such that overall the parallel-connected converters share the power conversion load in a predetermined manner.

Claims

1. A distributed power system comprising:

a direct current (DC) power source;

a plurality of autonomous inverters with respective inverter inputs adapted for connection in parallel to the DC power source and with respective inverter outputs adapted for connection in parallel to produce an alternating current (AC) power to a power grid; and

a plurality of control modules coupled respectively to the inverter inputs, wherein the control modules respectively control current drawn by the plurality of autonomous inverters from the DC power source responsive to the voltage of the DC power source;

wherein the plurality of autonomous inverters share unequally in inverting power from the DC power source to produce AC power to the power grid.

2. The distributed power system according to claim 1, further comprising:

a power module having an input coupled to the DC power source and an output coupled to the inverter inputs.

3. The distributed power system according to claim 2, wherein the power module is configured to maintain maximum peak power at the input coupled to the DC power source.

4. The distributed power system according to claim 2, wherein the power module is configured to control at maximum peak power at the output to the inverter inputs.

5. The distributed power system according to claim 1, further comprising:

a single maximum peak power tracking module connecting the DC power source to the control modules.

6. The distributed power system according to claim 1, wherein the control modules comprise:

a voltage loop block which upon comparing the voltage of the DC power source to at least one previously specified reference voltage, outputs a current reference signal based on the comparison; and

a current loop block which compares the current reference signal with a current signal proportional to the current in the DC power source.

7. A method comprising:

receiving, by a plurality of inverters coupled in parallel to a direct current (DC) power source, DC power from the DC power source, wherein the plurality of inverters comprises DC inputs and AC outputs and wherein the plurality of inverters produce an alternating current (AC) output power to an power grid;

autonomously controlling current drawn by each of the plurality of inverters from the DC power source responsive to a voltage of the DC input; and

upon reaching a voltage equilibrium at the DC input, each of the plurality of inverters inverting an unequal portion of power from the DC power source to the power grid.

8. The method according to claim 7, further comprising:

maintaining maximum peak power at an input of a power module, wherein the power module comprises an input coupled to the DC power source and an output coupled to the DC inputs of the plurality of inverters.

9. The method according to claim 7, wherein the AC outputs of the plurality of inverters are connected in parallel to the power grid.

10. A distributed power system comprising:

a direct current (DC) power source;

a plurality of power converters with respective power converter inputs adapted for connection in parallel to the DC power source and with respective power converter outputs adapted for connection in parallel; and

a plurality of control modules connected respectively to the power converter inputs, the control modules autonomously controlling current drawn by each respective power converter of the plurality of power converters from the DC power source responsive to the voltage of the DC input until a voltage equilibrium is reached at the power converter inputs wherein the plurality of power converters share unequally in inverting power from the DC power source to a combined output power.

11. A system comprising:

a plurality of autonomous inverters coupled in parallel to an power grid, wherein each of the plurality of autonomous inverters is configured to draw current from a corresponding direct current (DC) input; and

a controller configured to individually control, based on a DC input voltage for each of the plurality of autonomous inverters, current drawn by each one of the plurality of autonomous inverters from its corresponding DC input;

wherein each of the plurality of autonomous inverters is configured to draw an unequal portion of inverting power from the DC input to output power to an power grid.

12. A power system comprising:

a direct current (DC) power source;

a plurality of power converters comprising input terminals and output terminals, wherein the input terminals are coupled to the DC source in parallel, and wherein the output terminals are coupled to an electric network in parallel; and

a plurality of control modules, each coupled to a respective one of the power converters, and each configured to monitor the DC power source and autonomously vary the operation of the respective power converter according to the performance of the DC power source such that each respective power converter draws an unequal portion of power from the DC power source.

13. The power system of claim 12, wherein one or more of the plurality of power converters comprises an inverter.

14. The system of claim 12, wherein each of the plurality of control modules is configured to vary the current draw of a respective converter according to one of DC power or DC voltage of the DC power source.

15. The system of claim 12, wherein each of the plurality of control modules vary the current draw of the respective converter so as to maintain a functional relationship between input current and input voltage.

16. The system of claim 12, wherein the functional relationship is the same for all of the control modules.

17. The system of claim 12, wherein the DC power source comprises a plurality of power generating elements coupled to provide a single DC power output.

18. A method comprising:

drawing, using a plurality of parallel-coupled autonomous inverters, current from a direct current (DC) input;

detecting, for each of the plurality of parallel-coupled autonomous inverters, a DC input voltage; and

controlling, for each of the plurality of parallel-coupled autonomous inverters and based on the detected DC input voltage, current drawn from the DC input to reach an autonomous equilibrium in DC power conversion between the plurality of parallel-coupled autonomous inverters, wherein the plurality of parallel-coupled autonomous inverters draw unequal power from the DC input.