CIRCUIT ARRANGEMENT, METHOD FOR OPERATING A CIRCUIT ARRANGEMENT AND ELECTROLYSIS DEVICE

Abstract

A circuit arrangement and to a method for operating the circuit arrangement, particularly a circuit arrangement for the DC power supply of a plurality of parallel electrolysers, where the circuit arrangement has a rectifier which converts an input-side alternating voltage into an output-side first DC voltage. Each electrolyser is respectively connected in parallel to the output of the rectifier by a down converter converting the first DC voltage into a second DC voltage such that the second DC voltage drops over the electrolyser. Each of the down converters is controllable and/or regulatable in order to adapt the level of the second direct voltage.

Claims

1. A circuit arrangement for supplying DC current to multiple electrolysers connected in parallel, the circuit arrangement comprising: a rectifier that converts an input-side AC voltage into an output-side first DC voltage, wherein each electrolyser is connected in parallel with the output of the rectifier via a respective down-converter, which converts the first DC voltage into a second DC voltage, such that the second DC voltage is dropped across the electrolyser, wherein each of the down-converters is controllable and/or variable to adapt a level of its second DC voltage.

2. The circuit arrangement as claimed in claim 1, wherein the circuit arrangement comprises multiple switches, wherein each down-converter is bypassable by a respective switch.

3. The circuit arrangement as claimed in claim 1, wherein each down-converter comprises at least one energy-storage inductor and at least one transistor, which are connected in series with the electrolyser connected to the down-converter.

4. The circuit arrangement as claimed in claim 1, wherein the rectifier is controllable and/or variable to adapt a level of the first DC voltage.

5. The circuit arrangement as claimed in claim 1, wherein the rectifier comprises a thyristor assembly.

6. The circuit arrangement as claimed in claim 1, wherein the circuit arrangement comprises a capacitor, which is connected in parallel with the output of the rectifier.

7. The circuit arrangement as claimed in claim 1, wherein the input side of the rectifier is connected to a secondary of a transformer that converts a first AC voltage present on a primary of the transformer into a second AC voltage present on the secondary.

8. The circuit arrangement as claimed in claim 7, wherein the transformer comprises a tertiary, which is connected to a passive filter.

9. An electrolysis device, comprising: at least one circuit arrangement as claimed in claim 1, and multiple electrolysers, wherein each of the electrolysers comprises at least one proton exchange membrane.

10. A method for operating a circuit arrangement as claimed in claim 1, the method comprising: controlling and/or varying the first DC voltage and/or the second DC voltages on the basis of an amount of substance produced by at least one of the electrolysers by electrolysis and/or on the basis of an operating point of at least one of the electrolysers.

11. The method as claimed in claim 10, wherein the circuit arrangement comprises multiple switches, wherein each down-converter is bypassable by a respective switch, wherein the switches are controlled on the basis of an amount of substance produced by at least one of the electrolysers by electrolysis and/or on the basis of an operating point of at least one of the electrolysers.

12. The method as claimed in claim 10, wherein the rectifier is controlled and/or varied to adapt a level of the first DC voltage.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Further advantages and details of the invention will be obtained from the exemplary embodiments described below and from the drawings, in which:

[0024] FIG. 1 shows a schematic block diagram of a circuit arrangement according to the invention, and

[0025] FIG. 2 shows a schematic circuit diagram of a circuit arrangement according to the invention.

DETAILED DESCRIPTION OF INVENTION

[0026] FIG. 1 portrays a schematic depiction of a circuit arrangement 1 according to the invention. The circuit arrangement 1 is used for supplying DC current to multiple electrolysers 2, 3 connected in parallel, wherein each of the electrolysers 2, 3 is connected in parallel with the output of a rectifier 6 via a down-converter 4, 5. The rectifier 6 converts an AC voltage 7 present on the input side into a first DC voltage 8. This first DC voltage 8 is dropped across the branches 9, 10 comprising in each case one of the electrolysers 2, 3 and one of the down-converters 4, 5.

[0027] The first DC voltage 8 is converted by the down-converter 4 into the second DC voltage 11, which is dropped across the electrolyser 2. Accordingly, the first DC voltage 8 is likewise converted by the second down-converter 5 into the second DC voltage 12, which is dropped across the electrolyser 3. In addition to the two depicted electrolysers 2, 3, the circuit arrangement can naturally also be used for supplying DC voltage to further electrolysers, which are accordingly likewise connected in parallel with the output of the rectifier 6 via a respective down-converter as a further branch.

[0028] In order to be able to operate the electrolysers 2, 3 at a desired operating point, which is within a safe operating range, for example, the down-converters 4, 5 are controllable and/or variable to adapt a level of the second DC voltage 11 or 12. In addition, the rectifier 6 may also be controllable and/or variable to adapt a level of the first DC voltage 8. In particular, there may be provision for both the rectifier 6 and the down-converters 4, 5 and also further down-converters possibly present in further branches to be controllable or variable. To control or vary the rectifier 6 and/or the down-converters 4, 5, the circuit arrangement 1 can comprise a computing device 13, for example, by means of which the rectifier 6 and/or the down-converters 4, 5 can be controlled or varied. The computing device 13 may be connected to one or more measuring means (not depicted here) for this purpose, which can be used to measure for example an amount of substance produced by one of the electrolysers 2, 3, a respective resistance of one or more of the electrolysers 2, 3 and/or a respective flow of current through one or more of the electrolysers 2, 3. The control and/or variation of the rectifier 6 to adapt the level of the first DC voltage 8 or a control or variation of the down-converters 4, 5 to adapt the level of the second DC voltages 11, 12 can take place on the basis of the determined amount of substance and/or on the basis of the respective resistance of the electrolysers 2, 3 and/or the respective flow of current through the electrolysers 2, 3, for example. This also applies accordingly to further electrolysers and further down-converters that may be present in addition to the branches 9, 10. The down-converters 4, 5 and further down-converters possibly present are part of the circuit arrangement 1, to which the electrolysers 2, 3 and further electrolysers possibly present can be connected. In addition to the circuit arrangement 1, an electrolysis device 14 according to the invention also comprises all of the electrolysers connected to said circuit arrangement. Each of these can comprise at least one proton exchange membrane, for example, the proton exchange membrane being designed in particular to produce hydrogen by the electrolysis of deionized and/or distilled water.

[0029] FIG. 2 depicts a schematic circuit diagram of a circuit arrangement 1 according to the invention. In accordance with the portrayal in FIG. 1, the branch 9 comprises the electrolyser 2 and the down-converter 4. Furthermore, the branch 9 in this exemplary embodiment comprises a switch 15 of the circuit arrangement 1, by means of which the DC-DC voltage converter 4 can be bypassed. The branch 10 accordingly comprises the electrolyser 3 and also the down-converter 5 and the switch 16 of the circuit arrangement 1.

[0030] Each of the down-converters 4, 5 comprises a transistor 17, an energy-storage inductor 18 and a diode 19. Each of the transistors 17 and the energy-storage inductors 18 is arranged in series with the respective electrolyser 2 or 3 supplied with power via the down-converter. Each of the diodes 19 is accordingly connected in parallel with the respective electrolyser 2, 3. The transistor 17 can be used to vary the level of the respective second DC voltage 11, 12 provided by the down-converter 4 or 5 and dropped across the electrolyser 2 or 3. To this end, the transistors 17 may be connected to the computing device 13 (not depicted here), for example, with the applicable control for varying and/or controlling the down-converters 4, 5 taking place via the computing device 13. Furthermore, it is possible for the switches 15, 16 to be controllable, in particular likewise via the computing device 13, so that when the switch 15, 16 is closed the down-converters 4, 5 are bypassed. When the down-converter 4, 5 is bypassed, that is to say when the switch 15, 16 is closed, the first DC voltage 8 produced by the rectifier 6 is dropped directly across the electrolyser 2 or 3, that is to say that the electrolysers are supplied with power from an intermediate circuit for the first DC voltage 8.

[0031] The rectifier 6 in this exemplary embodiment comprises a thyristor assembly, which means that the level of the first DC voltage 8 can be adapted by controlling the rectifier 6. To stabilize the first DC voltage 8 produced by the rectifier 6, there is furthermore provision for a capacitor 33, which is connected in parallel with the output of the rectifier 6. The opportunity to be able to influence the level of the second DC voltages 11, 12 simply by adapting the level of the first DC voltage 8 allows the size of the energy-storage inductors 18 in the down-converters 4, 5 to be kept down.

[0032] The electrolysers 2, 3 connected to the circuit arrangement 1 comprise a proton exchange membrane, for example, an inductance 20, 21 and a resistor 22, 23 being depicted as an equivalent circuit diagram for each of said electrolysers in FIG. 2. The electrolysers 2, 3 are fed by means of the second DC voltages 11, 12 provided by the circuit arrangement 1 and are used to produce one or more substances by electrolysis. Each of the electrolysers 2, 3 can be assigned a measuring means 24, 25, which can be used to measure the flow of current through the respective electrolyser 2, 3, for example. The flow of current measured by the measuring means 24, 25 can be taken as a basis for controlling and/or varying the rectifier 6 and/or the down-converters 4, 5.

[0033] In this exemplary embodiment, a variability of the rectifier 6 is obtained for example as a result of the choice of a trigger time for the thyristors of the thyristor assembly of the rectifier 6. The second DC voltages 11, 12 produced by the down-converters 4, 5 can additionally be adapted by controlling the transistors 17, for example by pulse width modulation. In addition or as an alternative to a current measurement, the measuring means 24, 25 can also determine the voltage drop across the respective electrolyser 2, 3 and/or can determine its resistance, wherein the rectifier 6 and/or the down-converters 4, 5 can additionally or alternatively also be varied on the basis of one of these quantities. The resistances 22, 23 of the electrolysers 2, 3 can change during operation. The reason for such a resistance change may be aging effects in the electrolyser 2, 3 and/or temperature changes or the like, for example. The operation of the circuit arrangement 1 as provided for according to the invention can compensate for such effects by adapting the level of the first DC voltage 8 by controlling and/or varying the rectifier 6 and/or by adapting the level of the second DC voltage 11, 12 by controlling and/or varying the down-converters 4, 5.

[0034] Current is supplied to the rectifier 6 in this exemplary embodiment via a transformer 26 that converts a first AC voltage present on a primary 27 into a second AC voltage present on a secondary 28. Both the first AC voltage and the second AC voltage may be a high voltage. For example it is possible for a first AC voltage in a range between 6 kV and 100 kV to be present on the primary, said first AC voltage being transformed into a second AC voltage in a voltage range between 100 V and 1 kV that is present on the secondary 28. The transformer 26 furthermore comprises a tertiary 29, to which a passive filter 30 is connected. The passive filter 30 comprises an inductance 31 and a capacitance 32. The filter 30 may be adapted such that it damps at least one harmonic produced by the rectifier 6, for example produced as a result of the switching of the thyristor assembly and/or one or more other switchable components of the rectifier 6. Such damping by the filter 30 has an advantageous effect on the control and/or variation of the first DC voltage 8 or the second DC voltages 11, 12.

[0035] The electrolysers 2, 3 can be used for example to produce hydrogen by electrolysis of water. Other purposes of use, such as for example for chlorine alkali electrolysis, are also conceivable, however.

[0036] A further opportunity for controlling and/or varying the first DC voltage 8 and/or the second DC voltages 11, 12 arises when the electrolysers 2, 3 are adjusted to a respective operating point. This operating point may be dependent on the amount of substance to be produced by the electrolysis, for example. In this case, there may be provision for additional measuring means (not depicted here) that measure an amount of substance currently produced by means of the respective electrolysers 2, 3, the computing device 13 subsequently being able to be used to control and/or vary the rectifier 6 and/or the down-converters 4, 5, for example.

[0037] Although the invention has been illustrated and described more specifically in detail by means of the preferred exemplary embodiment, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by a person skilled in the art without departing from the scope of protection of the invention.