Method for the starting of an electrolysis system, and electrolysis system for carrying out the method

Patent metadata

Field	Value
Publication number	US-2024128857-A1
Application number	US-202318396810-A
Country	US
Kind code	A1
Filing date	Dec 27, 2023
Priority date	Jul 1, 2021
Publication date	Apr 18, 2024
Grant date	—

Abstract

A method for starting an electrolysis system is disclosed. A supply circuit has an AC terminal connected to an AC grid, a DC terminal connected to an electrolyzer, and an AC/DC converter arranged between the AC terminal and the DC terminal. The method includes charging an output capacitor connected to a DC converter terminal of the AC/DC converter, by operating the electrolyzer in a reverse mode, while the AC/DC converter is connected to the electrolyzer and disconnected from the AC grid, connecting the AC/DC converter to the AC grid, reversing the operation of the electrolyzer from the reverse mode to a normal mode as a DC load, to suppress a power flow between the AC grid and the electrolyzer, and operating the electrolyzer in the normal mode with electrical power drawn from the AC grid which is rectified by the AC/DC converter.

First claim

What is claimed is:

1 . A method for a starting of an electrolysis system, comprising an electrolyzer and a supply circuit or unit operating as a rectifier, wherein the supply circuit or unit has an AC terminal connected to an AC grid, a DC terminal connected to the electrolyzer, and an AC/DC converter arranged between the AC terminal and the DC terminal, comprising:
charging an output capacitor, which is connected to a DC converter terminal of the AC/DC converter, by operating the electrolyzer in a reverse mode as a DC voltage source, while the AC/DC converter is in a state in which it is connected to the electrolyzer and disconnected from the AC grid, connecting the AC/DC converter to the AC grid, reversing an operation of the electrolyzer from the reverse mode to a normal mode as a DC load, wherein, during the reversing of the operation, a power flow between the AC grid and the electrolyzer is completely or at least largely suppressed, and operating the electrolyzer in the normal mode as a DC load with electrical power which is drawn from the AC grid by way of the supply circuit or unit and which is rectified by way of the AC/DC converter.

2 . The method as claimed in claim 1 , wherein the output capacitor is charged to a DC voltage whose value corresponds to at least a rectified value of an AC voltage present at the AC terminal.

3 . The method as claimed in claim 1 , wherein before connecting the AC/DC converter to the AC grid, generating an AC voltage by the AC/DC converter and synchronizing the generated AC voltage with an AC voltage present at the AC terminal of the supply circuit or unit.

4 . The method as claimed in claim 1 , wherein for reversing the operation, disconnecting the AC/DC converter from the electrolyzer is effected, and reversing the operation of the electrolyzer from the reverse mode to the normal mode is effected while the electrolyzer is in a state in which it is disconnected from the AC/DC converter, and wherein the AC/DC converter is connected to the electrolyzer again after reversing the operation has been effected.

5 . The method as claimed in claim 1 , wherein the AC/DC converter is selectively connected to the electrolyzer via a low-impedance connection and a high-impedance connection, and wherein for reversing the operation, disconnecting the low-impedance connection of the AC/DC converter from the electrolyzer is effected, reversing the operation of the electrolyzer from the reverse mode to the normal mode is effected in a disconnected state of the low-impedance connection between the AC/DC converter and the electrolyzer, and wherein the AC/DC converter is connected to the electrolyzer with low impedance again after reversing the operation has been effected.

6 . The method as claimed in claim 4 , wherein disconnecting the AC/DC converter from the electrolyzer is effected only if the AC/DC converter is connected to the AC grid.

7 . The method as claimed in claim 5 , wherein disconnecting the low-impedance connection between the AC/DC converter and the electrolyzer is effected only if the AC/DC converter is connected to the AC grid.

8 . The method as claimed in claim 1 , wherein a terminal of the electrolyzer having a DC voltage>0V is connected to the output capacitor via a precharge resistor or via a DC/DC converter.

9 . The method as claimed in claim 1 , wherein the electrolyzer is connected to the output capacitor of the supply circuit or unit while a terminal of the electrolyzer is in a state in which it is at least largely free of voltage, and the electrolyzer is put into the reverse mode while in a state connected to the supply circuit or unit.

10 . An electrolysis system having an electrolysis unit comprising an electrolyzer, and having a supply circuit or unit, which feeds the electrolyzer from an AC grid, wherein the supply circuit or unit comprises:
an AC terminal configured to connect to an AC grid, a DC terminal configured to connect to the electrolyzer, an AC/DC converter arranged between the AC terminal and the DC terminal, an AC disconnection circuit configured to connect an AC converter terminal of the AC/DC converter to the AC terminal, and a DC disconnection circuit configured to connect a DC converter terminal of the AC/DC converter to the DC terminal, a control circuit configured to control the electrolysis system, wherein the electrolysis system is configured to carry out a method, comprising: charging an output capacitor, which is connected to a DC converter terminal of the AC/DC converter, by operating the electrolyzer in a reverse mode as a DC voltage source, while the AC/DC converter is in a state in which it is connected to the electrolyzer and disconnected from the AC grid, connecting the AC/DC converter to the AC grid, reversing an operation of the electrolyzer from the reverse mode to a normal mode as a DC load, wherein, during the reversing of the operation, a power flow between the AC grid and the electrolyzer is completely or at least largely suppressed, and operating the electrolyzer in the normal mode as a DC load with electrical power that is drawn from the AC grid by way of the supply circuit or unit and that is rectified by way of the AC/DC converter.

11 . The electrolysis system as claimed in claim 10 , wherein the supply circuit or unit is free of an AC-side precharge resistor.

12 . The electrolysis system as claimed in claim 10 , wherein the DC disconnection circuit of the supply circuit or unit includes a series circuit formed by a precharge resistor and a precharge switch, and a switch arranged in parallel with the series circuit, or in that the DC disconnection circuit includes a DC/DC converter.

13 . The electrolysis system as claimed in claim 10 , wherein the supply circuit or unit comprises voltage sensors configured to detect an AC voltage dropped across the AC disconnection circuit and/or a DC voltage dropped across the DC disconnection circuit.

14 . The electrolysis system as claimed in claim 10 , wherein the control circuit is embodied as a separate control circuit configured to control the supply circuit or unit and also the electrolysis unit, or wherein the control circuit is at least partly integrated into a controller of the supply circuit or unit and/or a controller of the electrolysis unit.

15 . The electrolysis system as claimed in claim 10 , wherein the AC/DC converter comprises a transistor-based bridge circuit.

16 . The electrolysis system as claimed in claim 10 , wherein the supply circuit or unit comprises a passive filter configured to filter clock-frequency interference currents.

17 . The electrolysis system as claimed in claim 10 , wherein the AC/DC converter is configured to facilitate a bidirectional power flow.

18 . The electrolysis system as claimed in claim 10 , wherein the electrolyzer comprises a solid oxide electrolyzer or a PEM electrolyzer and is configured to provide electrical energy from a chemical energy carrier in the reverse mode.

Assignees

• Sma Solar Technology Ag
• Sunfire Gmbh

Inventors

• Unru Alexander
• Koch Eike Rafael

Classifications

• H02M1/36 Primary

  Means for starting or stopping converters · CPC title

• C25B1/04 Primary

  by electrolysis of water · CPC title

• C25B9/65

  Means for supplying current; Electrode connections; Electric inter-cell connections · CPC title

• C25B15/02

  Process control or regulation · CPC title

• C25B15/06

  Detection or inhibition of short circuits in the cell · CPC title