Circuit assembly, electrolysis device, and method for operating a circuit assembly or an electrolysis device

Abstract

The invention relates to a circuit assembly comprising at least one coil assembly (1) with a first coil (2) and a second coil (3), the first coil (2) being connected to a DC voltage side of a rectifier (8) of the circuit assembly (7), and the second coil (3) being connected to a power source (12) of the circuit assembly (7), the first coil (2) and the second coil (3) being coupled to each other via a coupling component (4) of the coil assembly (1), said coupling component forming a core of each of the coils (2, 3).

Description

[0001] Description

[0002] Circuit arrangement, electrolysis device and method for operating a circuit arrangement or an electrolysis device

[0003] The invention relates to a circuit arrangement comprising at least one coil arrangement with a first coil and a second coil, wherein the first coil is connected to a DC voltage side of a rectifier of the circuit arrangement and the second coil is connected to a current source of the circuit arrangement. The invention further relates to an electrolysis device and a method for operating a circuit arrangement or an electrolysis device.

[0004] Chemical electrolysis processes, such as hydrogen electrolysis, are carried out using electrolyzers powered by direct current. In industrial-scale electrolysis, the direct current is supplied, for example, by line-connected rectifiers. During this rectification of a mains-side alternating current, certain voltage fluctuations can occur due to the operating principle of the electrolyzer.

[0005] Rectifier harmonics are generated, which can put a strain on the AC and / or DC power grid. One way to reduce this strain is, for example, a higher-pulse system in which several rectifiers are operated with a phase shift relative to the grid voltage to generate the DC current. However, this can lead to problems on the

[0006] This can lead to circulating currents on the DC side, as the instantaneous values ​​of the generated DC voltages of the individual rectifiers may differ, and therefore circulating currents can flow between the rectifiers. To solve this problem, a DC choke can be used between the two rectifiers, or several DC chokes can be used.

[0007] To avoid harmonics on the DC side, the use of one or more DC chokes is also known. Such a DC choke can be used, for example, in any DC system that includes a rectifier. The use of a

[0008] The disadvantage of using a DC choke in a DC system is that each coil requires a large amount of iron, as the iron core of the DC choke is completely presaturated by the DC current generated to operate the electrolyzers. Furthermore, the required amount of iron is needed for each DC choke or rectifier used.

[0009] A suction choke connected between two DC systems can also be very large, since the DC suction choke must absorb the voltage difference between the two DC systems due to the phase shift between the two rectifiers. Furthermore, depending on the pulsation of the system, several suction chokes for different frequencies may be necessary to achieve sufficient filtering of harmonics. In this case, too, the suction chokes used each require a large iron core. Due to the high DC currents required for industrial electrolysis applications, considerable demands are placed on the suction chokes used, which is associated in particular with a substantial iron core size and thus also with a considerable size, weight, and high cost of the chokes.

[0010] The invention is therefore based on the objective of providing a circuit arrangement by which the need for iron for a DC choke can be reduced.

[0011] To solve this problem, in a circuit arrangement of the type mentioned above, the invention provides that the first coil and the second coil are coupled to each other via a coupling component of the coil arrangement, each forming a core of the coils. The first coil, which is connected to the DC side of the DC converter of the circuit arrangement, is used as a DC choke for smoothing the DC current or as a smoothing device for smoothing the DC current or attenuating the harmonics superimposed on the DC current.The second coil, coupled to the first coil via the coupling element as a common core, can act as a compensation coil when appropriately energized. This means that the magnetic flux generated by the second coil opposes the magnetic flux generated by the first coil, which carries the direct current produced by the rectifier, within the common coupling element. This results in a complete or at least partial compensation of the magnetic flux generated by the first coil. Due to this compensation, the amount of iron within the first coil can be reduced without reducing the coil's inductance, which is necessary for smoothing the direct current. In this way, despite the reduced iron content within the first coil, smoothing of the direct current (or damping of harmonics) can still be achieved.

[0012] The coupling element connecting the first and second coils forms a core for each coil, or a coil core for the first coil and a coil guide for the second coil. The coupling element can extend at least partially within the windings of the first coil and the windings of the second coil. The coupling between the coils created by the coupling element is magnetic coupling, so that during operation of the circuit arrangement, a magnetic flux generated by the second coil can counteract the magnetic flux generated by the first coil within the coupling element.

[0013] To generate the magnetic flux within the second coil, it is connected to a current source within the circuit. This current source can be a DC source, which, due to the function of the second coil, can also be referred to as a compensation current source. In principle, a permanent magnet can also be used instead of the compensation current source and the second coil. However, using the second coil connected to the current source advantageously allows for adjusting the DC current supplying the second coil, thus enabling different strengths of the magnetic flux generated by the second coil, or different levels of compensation.

[0014] According to the invention, the coupling element can be a yoke-shaped iron core. By designing the coupling element as an iron core, magnetic coupling between the first and second coils is enabled. The coupling element designed as an iron core can be a single piece or multiple pieces. A yoke-shaped design of the iron core allows the first and second coils to each be arranged on a leg of the coupling element. To facilitate the assembly of the coil arrangement of the circuit arrangement, it can be provided, in particular, that the coupling element comprises a U-shaped or essentially U-shaped element and an I-shaped or essentially I-shaped element. The elements can be assembled to form a yoke by arranging the I-shaped element on the opening of the U-shaped element in such a way that a closed yoke of the coupling element is formed.

[0015] The compensation arrangement according to the invention makes it possible to significantly reduce the amount of iron, in particular to use less iron than would be necessary to avoid saturation without considering the compensation flux. Thus, it can be provided that the amount of iron in the yoke-shaped iron core is less, in particular less than half, than the amount required to completely saturate the coil core of the first coil by the maximum flux flowing through the first coil generated by the rectifier.

[0016] The magnetic flux generated by direct current is chosen without taking into account a magnetic flux generated by the second coil.

[0017] According to the invention, the coil arrangement can be configured such that the second coil has a higher number of turns than the first coil. This has the advantage that the current through the second coil can be smaller than the current through the first coil to compensate for the magnetic flux generated by the current flowing through the first coil. This is particularly important in circuit arrangements used for operating electrolyzers on an industrial scale, where very high currents are required.

[0018] Since direct currents can flow through the first coil, a lower current can be fed into the second coil by increasing the number of turns. For example, the first coils can each be designed for direct currents with a current between 100 A and 1 kA.

[0019] According to the invention, the circuit arrangement can comprise several rectifiers and several coil arrangements, wherein the first coils of the coil arrangements are each connected to a different rectifier. In particular, each rectifier of the circuit arrangement can be connected to a first coil of one of the coil arrangements; thus, it is advantageous for each

[0020] A rectifier contains a coil arrangement. The first coils of the coil arrangement can thus, for example, smooth the generated direct currents when the rectifiers are operated in parallel.

[0021] Furthermore, according to the invention, the second coils of the coil arrangement can be connected to the power source together, particularly in a series connection. This allows the second coils of all coil arrangements to be supplied jointly via the power source when several rectifiers are operated in parallel and each is connected to a first coil. In a series connection of the second coils, the compensation current generated by the power source flows through all second coils and serves there to generate the magnetic flux used for compensation. In this way, the current requirement of the circuit arrangement according to the invention can be advantageously reduced. The ratio between the number of turns of the first coil and the number of turns of the second coil can be the same or different for the coil arrangements. In the case of rectifiers operated with the same output current, the ratio of the second coil to the number of turns of the second coil can be the same or different.

[0022] In rectifiers, the number of turns and / or the ratios of the number of turns for the coil arrangements can be the same. If the rectifiers are operated with different output currents, the turn ratios of the coil arrangements can be different, so that the compensating current through the second coils can compensate for the magnetic flux generated by the current in the first coil.

[0023] According to the invention, the current source can be adjustable and, in particular, configured as a rectifier, and / or the rectifier(s) can be adjustable and / or configured as a three-phase rectifier, in particular as a B6 bridge rectifier. The adjustability of the current source also allows the magnetic flux generated by the second coil(s) to be controlled, so that the compensation function of the second coil can be adapted to the current operating conditions of the rectifier(s). A current source configured as a rectifier can, for example, be supplied via the same power grid as the rectifier(s).

[0024] Circuit arrangement. The adjustable rectifier(s), which are advantageously designed as three-phase rectifiers or B6 bridge rectifiers, makes it possible to adjust the total current generated by the rectifier(s) and thus, for example, to control the operation of an electrolysis unit connected to the circuit arrangement. In a preferred embodiment of the invention, the rectifier(s) may be connected on the AC side to a secondary winding of at least one transformer of the circuit arrangement. In a circuit arrangement comprising several rectifiers, a phase shift with respect to the AC voltage supplied on the AC side may exist between the secondary windings.The number of secondary windings operating out of phase with respect to one period of the AC voltage supplied determines the pulsation of the circuit arrangement. The transformers can, for example, transform a three-phase voltage supplied on the primary side (or AC side), particularly a medium or high voltage from a power grid, into a lower three-phase AC voltage applied to the secondary windings. This three-phase AC voltage applied to the secondary windings can then be converted into a DC voltage via the rectifier connected to the respective secondary winding, or a corresponding three-phase AC current delivered via the secondary windings can be converted into a DC current via the rectifiers.

[0025] For an electrolysis device according to the invention, it is provided that it comprises a circuit arrangement according to the invention, wherein the first coil or the first coils of the

[0026] The circuit arrangement is connected to at least one electrolyzer of the electrolysis device. For example, the first coils of several coil arrangements of the circuit arrangement can be connected in parallel to achieve a high total current for operating the at least one electrolyzer. For example, the first coils can each be designed for direct currents with a current between 100 A and 1 kA, the total current thus being the sum of the currents flowing through the first coils. All advantages and embodiments described above for the circuit arrangement according to the invention apply accordingly to the electrolysis device according to the invention.

[0027] For a method according to the invention for operating a circuit arrangement or an electrolysis device according to the invention, it is provided that the first coil and the second coil of the at least one coil arrangement are energized in such a way that the magnetic flux generated by the second coil opposes the magnetic flux generated by the first coil, at least within the common coupling element. This allows for a complete or at least partial compensation of the magnetic flux generated by the first coil in the section of the coupling element acting as the core of the first coil.If a current with current strength Ii flows through the first coil and the first coil comprises n turns and the second coil m turns, then a current strength I2 = Ii · (n / m) can be set for the current flowing through the second coil, whereby the current directions of Ii and I2 are chosen such that the magnetic flux generated by the second coil opposes the magnetic flux generated by the first coil, at least within the common coupling element.

[0028] According to the invention, it can be provided that a useful direct current generated by the rectifier(s) and a compensating direct current generated by the current source are controlled on the basis of a common relative target current specification.

[0029] The target current can be, for example, a value between 0%, which corresponds to a switched-off state of the circuit arrangement, and 100%, which corresponds to maximum DC output by the circuit arrangement. With a constant turns ratio between the turns n of the first coil and the turns m of the second coil of the least one coil arrangement, the magnetic flux generated is directly proportional to the corresponding current strengths of the useful current and the compensation current, thus advantageously enabling simple control of both the rectifier and the current source of the circuit arrangement.

[0030] All the advantages and features described above in relation to the circuit arrangement and electrolysis device according to the invention also apply accordingly to the method according to the invention.

[0031] Further advantages and details of the invention will become apparent from the drawings. These are schematic representations and show:

[0032] Fig. 1 shows a coil arrangement of a circuit arrangement according to the invention, and

[0033] Fig. 2 shows a circuit diagram of an electrolysis device according to the invention.

[0034] Figure 1 shows a coil arrangement 1 of a circuit arrangement according to the invention. The coil arrangement 1 comprises a first coil 2 and a second coil 3. Furthermore, the coil arrangement 1 includes a coupling element 4. The coupling element 4 comprises a U-shaped element 5 and a substantially I-shaped element 6, which is arranged on the U-shaped element 5 such that the coupling element 4 has a yoke-like overall shape. The first coil 2 is coupled to the second coil 3 via the coupling element 4. The coupling element 4 also forms a core for both the first coil 2 and the second coil 3.

[0035] The first coil 2 has n turns, and the second coil 3 has m turns. The number of turns shown for the first coil 2 and the second coil 3 is for illustrative purposes only and should be understood as purely schematic. The first coil 2 can, for example, be designed for direct currents with a current between 100 A and 1 kA, while the second coil 3 can be designed for lower currents, depending on the turns ratio n / m.

[0036] Due to the coupling of the first coil 2 with the second coil 3 via the coupling component 4, a magnetic flux ® generated by the current Ii flowing through the first coil 2 can DC in coupling component 4 wholly or partially due to the magnetic flux F KOMR^ which is generated by the current I2 flowing through the second coil 3, is compensated. This compensation makes it possible to advantageously reduce the amount of iron inside the first coil 2 without significantly affecting its properties with regard to smoothing the current Ii.

[0037] Figure 2 shows a circuit arrangement 7 according to the invention. The circuit arrangement 7 comprises four coil assemblies 1 and four rectifiers 8. The first coils of the coil assemblies 1 are each connected to the DC side of one of the rectifiers 8. The circuit arrangement 7 further comprises two transformers 9, each having one primary winding 10 and two secondary windings 11. The primary windings 10 of the transformers 9 are connected, for example, to a power grid, e.g., a medium-voltage grid or a high-voltage grid. The secondary windings 11 of each transformer 9 can each have a phase shift relative to one another, for example, of 30°. Furthermore, the transformers 9 can be operated such that the primary windings 10 have a phase shift relative to one another of 15°, resulting in an overall pulsation of 24 for the circuit arrangement 7 shown.

[0038] The three-phase alternating current supplied by the secondary windings 11 is converted into a direct current by the rectifiers 8, which flows as a current Ii through a first coil 2 of the coil arrangements 1. The first coils 2 of the coil arrangements 1, acting as DC chokes, smooth the currents Ii and, consequently, the total direct current I resulting from the sum of the currents Ii. G E S The magnetic flux generated in the coupling element 4 by the first coils 2 due to the currents Ii can be fully or partially compensated by the current I2 flowing through the second coils 3 of the coil arrangements 1. The second coils 3 of the coil arrangements 1 are connected in series and to a current source 12 that generates the current I2.

[0039] The circuit arrangement 7 can be part of an electrolysis device comprising at least one electrolyzer 13, wherein the at least one electrolyzer 13 is supplied by the total direct current I resulting as the sum of the currents Ii. G E S is fed.

[0040] In the case of equal currents Ii, the same turns ratio n to m of the turns of the first coil n and the second coil m can be used in each of the coil arrangements 4. In this way, the current I2 flowing through all second coils 3 provides the same compensation for the magnetic flux generated by the respective first coils 2 in each of the coil arrangements 1. DC Achieved. The complete or partial compensation of the magnetic flux ® DC through the magnetic flux F KOMR^ which is generated by the current I2 flowing through the second coils 3 connected in series, enables a reduction of the iron content in the respective first coils 2 while maintaining their inductance, so that when smoothing the direct current Ii generated by the rectifiers 8 or the total current I G E S Despite the reduced iron content in the first coils 2, no negative effects occur.

[0041] When the circuit arrangement 7 or an electrolysis device comprising the circuit arrangement 7 is operated with a method according to the invention, the signs of the currents Ii and I2 are selected such that the first coils 2 and the second coils 3 of the coil arrangements 1 are energized in such a way that the magnetic flux generated by the second coils 3 opposes the magnetic flux generated by the first coils 2, at least within the respective common coupling element 4. The useful direct current I generated by the rectifiers 8 G E S The compensation current I2 generated by the power source 12 is proportional to each other for the same winding ratios n to m, so that both the compensation by the current I2 and the current strength of the useful direct current or the total direct current I G E SThey can be jointly controlled based on a relative target current specification. The target current specification can, for example, be a value between 0%, which corresponds to an off state of the circuit arrangement, and 100%, which corresponds to a maximum DC output by the circuit arrangement.

[0042] The rectifiers 8 are designed as three-phase rectifiers. For example, the rectifiers 8 can be designed as B6 bridge rectifiers. The power source 12 can also be designed as a rectifier. For example, the power source 12 can also be supplied via the power grid, which is connected to the primary windings 10 of the transformers 9. Both the rectifiers 8 and the power source 12 can be adjustable.

[0043] The illustration of the circuit arrangement 7 with four rectifiers 8 is purely exemplary. A different number of rectifiers 8 and / or a different number of

[0044] Nine transformers are used.

[0045] Although the invention has been further illustrated and described by the preferred embodiment, the invention is not limited by the disclosed examples and other variations can be derived by a person skilled in the art without departing from the scope of protection of the invention. List of reference numerals

[0046] 1 Coil arrangement

[0047] 2 first coil

[0048] 3 second coil

[0049] 4 coupling component

[0050] 5 U-shaped element

[0051] 6 I-shaped element 7 Circuit arrangement 8 Rectifier 9 Transformer

[0052] 10 Primary winding

[0053] 11 Secondary winding

[0054] 12 Power source

[0055] 13 Electrolyzer

Claims

An electrolysis device, comprising: an electrolyzer, a plurality of coil assemblies, each coil assembly comprising a first coil and a second coil, a plurality of rectifiers, wherein a first terminal of the first coil of each one of the plurality of coil assemblies is connected to a DC voltage side of one of the plurality of rectifiers, and a second terminal of the first coil of each one of the plurality of coil assemblies is connected to the electrolyzer, wherein the second coil of each one of the plurality of coil assemblies are connected together in a series circuit with a current source, wherein the first coil and the second coil of each coil assembly are coupled to one another via a coupling component that forms a core of each of the first and second coils of each coil assembly. The electrolysis device as claimed in claim 1, wherein the coupling component is an iron core. The electrolysis device as claimed in claim 1, wherein the second coil of each one of the coil assemblies has a higher winding count than the first coil of the coil assembly. The electrolysis device as claimed in claim 1, wherein the first coil of each one of the plurality of coil assemblies is connected to a different one of the plurality of rectifiers. The electrolysis device as claimed in claim 1, wherein one or both of the current source and one or more of the plurality of rectifiers is controllable. The electrolysis device as claimed in claim 1, wherein one or more of the plurality of rectifiers is connected on an AC voltage side to a secondary winding of at least one transformer of the electrolysis device. A method for operating the electrolysis device as claimed in claim 1, the method comprising: the first coil and the second coil of at least one of the plurality of coil assemblies receiving currents in such a way that a magnetic flux generated by the second coil counteracts a magnetic flux generated by the first coil at least within the coupling component. The method as claimed in claim 7, further comprising: a direct current generated by at least one of the plurality of rectifiers and a compensation direct current generated by the current source controlled on the basis of a common, relative setpoint current specification. The electrolysis device as claimed in claim 2, wherein the coupling component is designed in the form of a yoke. The electrolysis device as claimed in claim 1, wherein the current source comprises a rectifier. The electrolysis device as claimed in claim 5, wherein the rectifier is designed as one or both of a three-phase rectifier, and a B6 bridge rectifier. 

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