String inverter system

Patent metadata

Field	Value
Publication number	US-10498253-B2
Application number	US-201816025401-A
Country	US
Kind code	B2
Filing date	Jul 2, 2018
Priority date	Sep 30, 2016
Publication date	Dec 3, 2019
Grant date	Dec 3, 2019

Abstract

A multi-inverter system with at least a string of inverters sharing a DC bus and outputting to a shared AC bus. Inverters are hot-swappable and configured to be turned on or off during powered cycles. Central control may comprise reducing power point tracking redundancies or promoting other operational changes at individual inverters of a group.

First claim

What is claimed is:

1. An inverter system comprising:
a plurality of peer inverters, each peer inverter of the plurality of peer inverters comprising an internal microcontroller, a driver circuit, and a DC/AC inverter comprising a plurality of switches, wherein the microcontroller controls the driver circuit and the driver circuit sends control signals to switches in the DC/AC inverter;
a shared AC junction electrically coupled to each of the peer inverters, the shared AC junction configured to output AC received from the plurality of peer inverters to a low voltage side of a transformer; and
a support rack coupled to and supporting at least two peer inverters,
wherein each peer inverter has its own enclosure,
wherein peer inverters of the plurality are configured to be manually coupled to and configured to be manually uncoupled from the shared AC junction.

2. The inverter system of claim 1 further comprising:
a system controller, the system controller configured to perform tracking functionality for two or more of the peer inverters and to send tracking instructions to two or more peer inverters for receipt and use by those two or more inverters.

3. The inverter system of claim 1 wherein each peer inverter has its own enclosure and its own heat dissipation mechanism and wherein the shared AC junction is electrically coupled to a utility transformer.

4. The inverter system of claim 1 wherein the shared AC junction is configured to output at least 120 VAC for receipt by a transformer.

5. The inverter system of claim 1 wherein peer inverters of the plurality further comprise hot-pluggable connectors and wherein each of the peer inverters of the plurality are configured to be manually coupled to and manually uncoupled from the support rack.

6. The inverter system of claim 1 wherein a station controller is in communication with the shared AC junction, the peer inverters, and the transformer.

7. The inverter system of claim 1 wherein the support rack is an electro-mechanical rack configured to support peer inverters of the plurality and configured to couple peer inverters of the plurality to a DC junction.

8. The inverter system of claim 1 wherein a station controller is in communication with the shared AC junction, the peer inverters, the transformer, and two or more photovoltaic (PV) panels.

9. A process of operating a peer inverter system, the process comprising:
identifying that a first inverter has been added to a group of peer inverters while the peer inverters were active and coupled between a DC input junction and an AC output junction;
after identifying that the first inverter has been added to the group of peer inverters, sending operating instructions to the first inverter, the operating instructions including instructions for an internal function of the first inverter to become inactive; and
monitoring operation of the first inverter and the other inverters of the group and sending corrective operating instructions to one or more inverters when voltage outputs exceed a target variance,
wherein peer inverters of the group are configured to be manually coupled to and configured to be manually uncoupled from a shared AC junction,
wherein each of the peer inverters output AC voltage to the shared AC junction, the shared AC junction configured to output AC received from the plurality of peer inverters to a low voltage side of a transformer, and
wherein a station controller is in communication with the shared AC junction, the peer inverters, and the transformer.

10. The process of claim 9 wherein the operating instructions select between adding or activating a peer inverter or further burdening existing peer inverters to accommodate an increased power demand.

11. The process of claim 9 further comprising:
bringing one or more peer inverters into operation to maintain a peak range of operating efficiency for one or more of the peer inverters in the group.

12. The process of claim 11 wherein the peak range is within 1% of the peak efficiency of power conversion for the one or more peer inverters in the group.

13. The process of claim 9 further comprising:
taking one or more peer inverters out of operation to maintain a peak range of operating efficiency for one or more of the peer inverters in the group.

14. The process of claim 9 wherein peer inverters of the group are brought into operation and taken out of operation in a repeating cycle such that over time each peer inverter of the group trends toward having an equivalent amount of operational time and nonoperational time as other peer inverters of the group.

15. A system for converting DC voltage to AC voltage, the system comprising:
one or more DC busses configured to receive DC voltage from a plurality of DC power sources;
a plurality of peer inverters, each peer inverter of the plurality of peer inverters comprising
an internal microcontroller,
a driver circuit, and
a DC/AC inverter comprising a plurality of switches,
wherein the microcontroller controls the driver circuit and the driver circuit sends signals controlling switches in the DC/AC inverter,
wherein each peer inverter of the plurality of is electrically coupled to a shared AC junction,
wherein each peer inverter of the plurality has its own enclosure; the shared AC junction configured to output AC received from the plurality of peer inverters to a low voltage side of a transformer;
wherein peer inverters of the plurality are configured to be manually coupled to and configured to be manually uncoupled from the shared AC junction, and

a support rack coupled to and supporting at least two peer inverters.

16. The system of claim 15 wherein the DC voltage received is a constant DC input from a PV system performing maximum power point tracking to maintain the constant DC input.

17. The system of claim 15 further comprising a central controller, the central controller having maximum power point tracking functionality.

18. The system of claim 15 wherein there is no distribution panel electrically coupled between the peer inverters and the transformer.

19. The system of claim 15 wherein a station controller is in communication with the shared AC junction, the peer inverters, the transformer, and two or more photovoltaic (PV) panels.

Assignees

• Sunpower Corp

Inventors

• Chapman Patrick L
• Judkins Zachary S
• Marshall Jacob

Classifications

• H02J2101/25

  involving maximum power point tracking control for photovoltaic sources · CPC title

• H02J2101/24

  Photovoltaics · CPC title

• H02S40/32

  comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules · CPC title

• H02J3/38

  Arrangements for feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel · CPC title

• H02M7/42 Primary

  Conversion of DC power input into AC power output without possibility of reversal · CPC title