Photovoltaic system having master and slave converters and control method of the same

Patent metadata

Field	Value
Publication number	US-12597845-B2
Application number	US-202218579630-A
Country	US
Kind code	B2
Filing date	Apr 24, 2022
Priority date	Nov 5, 2021
Publication date	Apr 7, 2026
Grant date	Apr 7, 2026

Abstract

A photovoltaic system and a control method. The photovoltaic system includes a master DC/DC converter; a slave DC/DC converter; a master DC/AC converter; and a slave DC/AC converter. The master DC/AC converter is configured to send a current instruction value and an input voltage of the master DC/AC converter to the slave DC/AC converter; and the slave DC/AC converter is configured to control an output current, based on an input voltage of the slave DC/AC converter, the current instruction value, and the input voltage of the master DC/AC converter, so that a current through the N wire is less than a preset current.

First claim

The invention claimed is:

1 . A photovoltaic system, comprising:
a master DC/DC converter; a slave DC/DC converter; a master DC/AC converter; and a slave DC/AC converter; wherein an input terminal of the master DC/DC converter is configured to be connected to a photovoltaic array, a positive output terminal of the master DC/DC converter is connected to a positive input terminal of the master DC/AC converter, a negative output terminal of the master DC/DC converter is connected to an N wire, and a negative input terminal of the master DC/AC converter is connected to the N wire; a negative input terminal of the slave DC/DC converter is connected to the negative output terminal of the master DC/DC converter, and a positive input terminal of the slave DC/DC converter is connected to the positive output terminal of the master DC/DC converter, a positive output terminal of the slave DC/DC converter is connected to the N wire, a negative output terminal of the slave DC/DC converter is connected to a negative output of the slave DC/AC converter, and a positive output terminal of the slave DC/AC converter is connected to the N wire; the master DC/AC converter is configured to send a current instruction value and an input voltage of the master DC/AC converter to the slave DC/AC converter; and the slave DC/AC converter is configured to control an output current, based on an input voltage of the slave DC/AC converter, the current instruction value, and the input voltage of the master DC/AC converter, so that a current through the N wire is less than a preset current.

2 . The photovoltaic system according to claim 1 , wherein the slave DC/AC converter is further configured to control the output current to be directly proportional to the input voltage of the slave DC/AC converter and the current instruction value, and inversely proportional to the input voltage of the master DC/AC converter, so that the current through the N wire is less than the preset current.

3 . The photovoltaic system according to claim 2 , wherein the slave DC/AC converter is further configured to control the output current to be U2*I1/U1, where the U2 is the input voltage of the slave DC/AC converter, the U1 is the input voltage of the master DC/AC converter, and the I1 is the current instruction value.

4 . The photovoltaic system according to claim 1 , wherein, in a case that an output power of the master DC/AC converter is not limited by the master DC/AC converter, the input voltage of the master DC/AC converter is a preset value.

5 . The photovoltaic system according to claim 1 , wherein, in a case that an output power of the master DC/AC converter is limited by the master DC/AC converter, the master DC/AC converter is further configured to collect the input voltage of the master DC/AC converter and send the collected input voltage of the master DC/AC converter to the slave DC/AC converter; or the slave DC/AC converter is further configured to directly collect the input voltage of the master DC/AC converter.

6 . The photovoltaic system according to claim 1 , wherein, in a case that the photovoltaic system is not power-limited, and an abnormal communication between the master DC/AC converter and the slave DC/AC converter is detected by the slave DC/AC converter, the slave DC/AC converter is configured to obtain the current instruction value based on the input voltage of the master DC/AC converter, the current through the N wire, the input voltage of the slave DC/AC converter and an output power of the slave DC/AC converter, and control the output current of the slave DC/AC converter based on the current instruction value, so that the current through the N wire is less than the preset current.

7 . The photovoltaic system according to claim 1 , wherein, in a case that the photovoltaic system is power-limited, and the input voltage of the master DC/AC converter sent by the master DC/AC converter is not received by the slave DC/AC converter, the slave DC/AC converter is configured to obtain the current instruction value based on the input voltage of the master DC/AC converter, the current through the N wire, the input voltage of the slave DC/AC converter and an output power of the slave DC/AC converter, and control the output current of the slave DC/AC converter based on the current instruction value, so that the current through the N wire is less than the preset current.

8 . The photovoltaic system according to claim 1 , wherein, in a case that low voltage ride through or high voltage ride through occurs in the photovoltaic system, the master DC/AC converter is configured to control the master DC/AC converter to output a first reactive power and control the slave DC/AC converter to output a second reactive power.

9 . A control method for a photovoltaic system, wherein the photovoltaic system comprises a master DC/DC converter, a slave DC/DC converter, a master DC/AC converter and a slave DC/AC converter; wherein an input terminal of the master DC/DC converter is configured to be connected to a photovoltaic array, a positive output terminal of the master DC/DC converter is connected to a positive input terminal of the master DC/AC converter, a negative output terminal of the master DC/DC converter is connected to an N wire, and a negative input terminal of the master DC/AC converter is connected to the N wire; a negative input terminal of the slave DC/DC converter is connected to the negative output terminal of the master DC/DC converter, and a positive input terminal of the slave DC/DC converter is connected to the positive output terminal of the master DC/DC converter, a positive output terminal of the slave DC/DC converter is connected to the N wire, a negative output terminal of the slave DC/DC converter is connected to a negative output of the slave DC/AC converter, and a positive output terminal of the slave DC/AC converter is connected to the N wire;
wherein the control method comprises: controlling the master DC/AC converter to send a current instruction value and an input voltage of the master DC/AC converter to the slave DC/AC converter; and controlling the slave DC/AC converter to control an output current, based on an input voltage of the slave DC/AC converter, the current instruction value, and the input voltage of the master DC/AC converter, so that a current through the N wire is less than a preset current.

10 . The control method according to claim 9 , the controlling the output current, based on the input voltage of the slave DC/AC converter, the current instruction value, and the input voltage of the master DC/AC converter, further comprises:
controlling the output current to be directly proportional to the input voltage of the slave DC/AC converter and the current instruction value, and inversely proportional to the input voltage of the master DC/AC converter, so that the current through the N wire is less than the preset current.

11 . The control method according to claim 10 , wherein, in a case that the photovoltaic system is not power-limited, the input voltage of the master DC/AC converter sent by the master DC/AC converter is not received by the slave DC/AC converter, the controlling the output current, based on the input voltage of the slave DC/AC converter, the current instruction value, and the input voltage of the master DC/AC converter, so that the current through the N wire is less than the preset current, further comprises:
obtaining the current instruction value, based on the input voltage of the master DC/AC converter, the current through the N wire, the input voltage of the slave DC/AC converter and an output power of the slave DC/AC converter, and controlling the output current of the sla

Assignees

• Sungrow Power Supply Co Ltd

Inventors

• Sun Shuai
• He Anran
• Chen Peng
• Wang Zhicheng
• Chen Xuebing

Classifications

• H02M1/0077

  Plural converter units whose outputs are connected in series · CPC title

• H02S40/32

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

• H02J2101/24

  Photovoltaics · CPC title

• Y02E10/56

  Power conversion systems, e.g. maximum power point trackers · CPC title

• H02M7/5387

  in a bridge configuration · CPC title