Device for supplying electrical consumer, in particular electrolysis device, with DC voltage

Abstract

The invention relates to a device for supplying at least one consumer (40), in particular an electrolysis device, with a DC voltage, comprising a plurality of switchable units (50) connected in parallel, each of which comprises at least one rectifier (16) and at least one converter (30), the converters (30) being operable in parallel with the rectifier (16) in a primary operation (21), and the converters (30) being operable in parallel with the rectifier (16) in a secondary operation (21). In a first operation (23), the converter (30) can be operated as a DC voltage converter (30) connected downstream of the rectifier (16) in order to supply the consumer (40) with a voltage (U), in a second operation (23), at least one second unit (56) is provided, in which the converter (30) can be operated as a DC voltage converter (30) connected downstream of the rectifier (16) in order to supply the consumer (40) with a voltage (U). The secondary unit is connected in parallel with the switchable unit (50).

Description

Technical Field

[0001] The invention relates to a device for supplying a load, in particular an electrolysis device, with a direct voltage. Background Art

[0002] EP 3752665 B1 discloses a circuit arrangement, a method for operating the circuit arrangement, and an electrolysis device. In order to supply a plurality of electrolysis devices connected in parallel with direct current, the circuit arrangement comprises a rectifier which converts an AC voltage on the input side into a first DC voltage on the output side, wherein each electrolysis device is connected in parallel to the output of the rectifier via a step-down transformer which converts the first DC voltage into a second DC voltage in such a way that the second DC voltage is stepped down at the electrolysis device, wherein each of the step-down transformers is designed to be controllable and / or adjustable in order to adapt the magnitude of the second DC voltage of the step-down transformer. Summary of the invention

[0003] The object on which the invention is based is to ensure efficient operation of an electrical load. This object is achieved by the solution according to the invention.

[0004] Compared with the prior art, the device according to the invention has the advantage that a topology is proposed, which ensures that the characteristic curve of the electrical appliance meets certain requirements. The area below the voltage range can be covered by at least one secondary unit, while the upper voltage range can be operated by a primary or secondary unit. Therefore, the desired power demand can be provided at high efficiency. However, the corresponding dynamic requirements during load operation changes can also be met. This can be achieved in a purposeful expansion by configuring the secondary unit as a non-switchable unit and / or as a switchable unit. It is particularly preferred to provide at least one non-switchable unit and at least one switchable unit. Therefore, power electronics can be saved compared to only fully equipped with a secondary unit.

[0005] In an expedient development, it is provided that several secondary units and / or several switchable units are selected in such a way that the characteristic curves generated by these units, in particular the current-voltage characteristic curve, intersect the characteristic curve of the load, in particular the current-voltage characteristic curve, at a point above the limit voltage. Particularly preferably, several secondary units and / or several switchable units are selected in such a way that the characteristic curves generated, in particular the current-voltage characteristic curve, intersect the characteristic curve of the load, in particular the current-voltage characteristic curve, at a point that is to the right of a percentage of the maximum current, in particular 50%. The desired operating state can thus be realized in a flexible manner.

[0006] In a suitable expansion, the secondary unit can be operated in a wider voltage range than the primary unit. This allows partial load operation to be covered very well.

[0007] In an expedient development, the primary unit and / or the secondary unit are designed to be switchable or deactivatable, in particular independently of one another. These units can thus be adapted particularly flexibly and quickly to different operating states.

[0008] Further expedient developments result from the concrete technical solutions and exemplary embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings show:

[0010] Figure 1 : Schematic block diagram of the circuit arrangement for a primary or secondary unit,

[0011] Figure 2 : topology of a stage conversion concept which selectively enables the switchable unit to operate as a primary unit or as a secondary unit,

[0012] Figure 3 : The relationship between the voltage characteristic curve of electrical appliances, especially electrolysis equipment, and the characteristic curve of the stage conversion concept,

[0013] Figure 4 : Illustration of the mismatched coordination of the characteristic curves with possible remedial measures,

[0014] Figure 5 : Graphical representation of the units required for different characteristic curves or operating conditions,

[0015] Figure 6 : The first topology for covering the lower voltage region,

[0016] Figure 7 : A second topology for covering the lower voltage region, and

[0017] Figure 8 : A third topology for covering the lower voltage region. DETAILED DESCRIPTION

[0018] The invention will be schematically represented on the basis of exemplary embodiments and will be described in detail below with reference to the drawings.

[0019] In particular, a high-power current source is required to supply power to an electrolysis device as a possible electrical consumer 40. The power source 12 is usually a mains connection. In order to adapt the electrical supply of the electrical appliance 40 to very different power supply conditions, such as occur, for example, when providing electrical energy, especially in the case of renewable energy, it is preferred to use a power supply according to the invention. Figure 1 and Figure 2 Circuit layout.

[0020] Figure 1The construction of the circuit arrangement is schematically shown. The upper arrangement is provided as a secondary unit 56 for the secondary operation 23. The rectifier 16 is supplied with power from a power source 12 providing an alternating current, such as a grid connection, via a coil 14 that enables a step-up chopper operation. The alternating voltage rectified by the rectifier 16 reaches the converter 30 via the intermediate circuit 26, which operates as a DC voltage converter and / or a step-down chopper in the secondary operation 23. The consumer 40, in particular the electrolysis device, is supplied with a DC voltage via a further coil 38 and a common output coil 46.

[0021] Figure 1 The arrangement below shows a primary unit 54 for primary operation 21. The power source 12 is connected to the rectifier 16 or AC / DC converter of the primary unit 54 via the corresponding coil 14. Subsequently, the DC voltage or output voltage of the rectifier 16 reaches the electrical appliance 40, in particular the electrolysis device, via the intermediate circuit 26 and the common output coil 46 to supply power to the electrical appliance. The primary unit 54 is characterized in that only the AC / DC converter is used as the rectifier 16. The possible voltage range in this embodiment is, for example, between 620V and 800V. When only the primary unit 54 is used, only a limited area (or a corresponding voltage range) of partial load can be achieved for the sub-electrical appliances 40.1, 40.2 or the electrical appliance 40. The primary unit is more cost-effective than the secondary unit 56, saves more space, and is also more efficient due to fewer components (no additional converter 30 is required).

[0022] The secondary unit 56 is characterized in that the AC / DC converter 16 is combined with a converter 30 designed as a direct current voltage converter or DC / DC converter. Figure 1 The voltage range shown in FIG. 5 is significantly larger for the secondary cell 56 , so that partial loads of up to 20% are possible.

[0023] exist Figure 2 The circuit technical implementation of the stage conversion concept is shown by way of example. The switchable secondary unit 50 shown here can be operated selectively as a primary unit 54 or as a secondary unit 56. The power source 12 is schematically designed as a three-phase grid connection. The circuit arrangement for supplying power to the electrolysis device 40 includes at least a rectifier 16 configured as a bridge circuit, which is connected to a converter 30 likewise implemented as a bridge circuit via an intermediate loop 26. If necessary, the converter 30 is used as a step-down transformer for developing a lower voltage U. The rectifier 16 is used as an inverter and, by way of example, includes three rectifier branches 20, 22, 24 connected in parallel to each other. In each rectifier branch 20, 22, 24, two switching devices 18 are respectively arranged in series with each other. In Figure 2In the embodiment, semiconductor switches such as IGBTs (insulated gate bipolar transistors) are used as switching devices 18, but other controllable power semiconductors such as MOSFETs made of SiC, GaN, etc. can also be used just as well. Between the two switches 18 of each rectifier branch 20, 22, 24, the individual phases of the power source 12 are conductively contacted via the respective coils 14. Therefore, the rectifier 16 is constructed as an active B6 bridge. The two output ends of the rectifier 16 are connected to the intermediate circuit 26. The rectifier 16 thus converts the AC voltage of the power source 12 into a DC voltage, and feeds the intermediate circuit 26 with the DC voltage. The intermediate circuit capacitor 28 is connected to the two output ends of the rectifier 16 in the intermediate circuit 26. Therefore, in the present embodiment, the intermediate circuit 26 is a DC voltage intermediate circuit.

[0024] A further converter 30 is provided, which in turn comprises three parallel branches 32, 34, 36, by way of example. In each of the parallel branches 32, 34, 36, two switching devices 18 are arranged in series with one another. The common potential of these branches 32, 34, 36 is in turn connected to the intermediate circuit 26. The converter 30 can also be connected to the power source 12, just like the rectifier 16. For this purpose, conductive contact with the corresponding phases of the power source 12 is made between the two switching devices 18 of each branch 32, 34, 36, respectively, which are respectively conducted via the corresponding further coils 38 and respectively via the first switch 41. The three phases respectively conducted via the first switch 41 are conducted to the converter 30 via the respective further coils 38 on the one hand, and are conducted at the branch point via the further switch 42 provided for each phase on the other hand and are brought together to the same potential after the further switch 42, in order to further contact the input of the electrolysis device 40. The common (high or positive) potential of the intermediate circuit 26 between the rectifier 16 and the converter 30 is conducted to the input of the electrolysis device 40 via the third switch 43. The other input of the electrolysis device 40 is at the same (low) potential as the reference potential of the intermediate circuit 26 or as the two bridge circuits 16, 30 which are also connected to the other input of the electrolysis device 40.

[0025] The switches 41, 42, 43 are components of a switching unit which enables the converter 30 to be operated selectively as a rectifier or AC / DC converter (particularly connected in parallel with the rectifier 16 which also functions as a step-up converter or AC / DC converter) and as a DC voltage converter DC / DC (particularly as a step-down transformer). The switching unit enables both the primary operation 21 (two bridge circuits 16, 30 connected in parallel and operated as rectifiers or AC / DC converters) and the secondary operation 23 (the converter 30 forms another stage and functions as a DC voltage converter or DC / DC converter, particularly a step-down transformer, which is coupled in series to the intermediate circuit 26). In the secondary operation 23, the first switch 41 is open, the other switch 42 is closed, and the third switch 43 is open. In the primary operation 21, the first switch 41 is closed, the other switch 42 is open, and the third switch 43 is closed.

[0026] By Figure 2 The topology shown in FIG. 5 in the form of a switchable secondary unit 50 can be switched between primary operation 21 and secondary operation 23. This topology can thus selectively replace a secondary unit 56 and a primary unit 54.

[0027] Figure 3 The ideal coordination of the characteristic curve 66 of an electrical load 40 is shown, which comprises, for example, two electrical loads 40.1, 40.2 connected in series, in particular a reactor of an electrolysis device, and a corresponding Figure 1 and 2 21 and 23). A power electronic device for a stage conversion concept (combined primary operation 21 and secondary operation 23) as explained in FIG. Here, the permitted areas (switching areas 60, permitted areas 61 for primary operation 21, permitted areas 63 for secondary operation 23) and the impermissible areas 62 are shown. The area in which the two permitted areas 61, 63 of primary operation 21 and secondary operation 23 overlap is understood to be the switchable area 60, so that in this area it is possible to switch between primary operation 21 and secondary operation 23 and vice versa. In addition, the required power P must vary below the power limit Pg1 of the power electronic device in primary operation 21. Due to the parallel connection of the rectifier 16 and the converter 30, in a first approximation, the power limit Pg1 in primary operation 21 is twice as high as in the secondary case (2*Pg2). This condition results in a hyperbola in the current-voltage diagram, because it is again applicable: P=U*I. In the current diagram, a power limit Pg1 of 3 MW is selected as an example.

[0028] Below Figures 6 to 8 The topological solution described in the embodiment is now used to connect the characteristic curve 66 of the load 40 to the characteristic curve 66 of the load 40. Figure 3In the event that the requirements shown in are not met. Figure 3 The voltage range 61 permitted for the primary operation 21 is shown. The characteristic curve 66 is characterized in a very simplified manner in that the voltage Ug (e.g. 620 V) is exceeded before Imax / 2 (Imax=~4000 A), or the characteristic curve 66 with the voltage U=Ug (e.g. Ug=620 V) is located to the left of Imax / 2. In this case, Imax is predetermined by the current-voltage characteristic curve of the load 40 (e.g. the electrolysis device reactor) and the maximum power of the load.

[0029] Figure 4 The key design of the stage conversion concept for a specific electrical consumer 40, in particular an electrolysis device, is shown. In addition to the boundary lines for the primary operation 21 and the secondary operation 23, the problematic characteristic curve 68 at 50° C. (the temperature of the electrical consumer or electrolysis device 40) and the corresponding problematic characteristic curve 69 at 70° C. (the temperature of the electrical consumer or electrolysis device 40) are also plotted. The problematic characteristic curve 69 clearly passes through the prohibited area 62 in the problematic area 72. The problematic characteristic curve 68 also slightly touches the prohibited area 62. Figure 4 The remedial measures and their effects are described in:

[0030] 1. Increase the number of cells installed in the reactor, which causes the reactor characteristic curve to shift parallel to the upper left (Countermeasure 74).

[0031] 2. The temperature of the load 40 or the reactor temperature is reduced in the critical region, which leads to a parallel shift of the reactor characteristic curve to the upper left (countermeasure 74 ).

[0032] 3. Increasing the power capability of the power electronics, which causes the hyperbola to shift parallel to the upper right (countermeasure 76).

[0033] 4. Using a transformer with a modified winding ratio on the input side, which leads to a reduction in the phase voltage and thus in the rectified voltage, which is, for example, 620 V (measure 78).

[0034] 5. Use of power electronics with increased voltage resistance, which results in an increase in the exemplary 800 V characteristic curve (increase in limit value Us).

[0035] Figure 5 Shown according to Figure 3 The characteristic curve 66 does not conform to the characteristic curve 47 (and the aging characteristic curve 48). It is desirable that the characteristic curve 66 (or the characteristic curve 48 according to Figure 5The intersection of the characteristic curve 47 of the voltage Ug (e.g. Ug=620 V) is located to the left of Imax / 2. The region below Ug or the exemplary 620 V can then be operated by half a two-stage branch or two-stage unit 50, 56, while the upper current region can be supplied with twice the number of one-stage units 54 or switchable two-stage units 50 operated in one-stage operation 21.

[0036] This is achieved, for example, by:

[0037] a plurality of secondary units 50 , 56 covers the current region of the characteristic curve 66 below the intersection of the reactor characteristic curve 66 and the lower voltage limit value Ug, for example 620 V, and

[0038] A number of primary cells 54 or primary or secondary cells 50 cover the current region of the characteristic curve 66 above the intersection point between the characteristic curve 66 and the voltage U=Ug (eg 620 V).

[0039] The region below the voltage limit value Ug is necessarily operated with the secondary unit 50, 56, since the primary unit 54 cannot reach the lower voltage region Ug. However, the upper voltage region (above the lower voltage limit value Ug) can be operated by the primary unit 54 or the secondary unit 50, 56, since both units 54; 50, 56 can generate an output voltage U above the lower limit voltage Ug.

[0040] For example, according to Figure 5 A characteristic curve 47 is given, which intersects the lower voltage limit value Ug (for example at 620 V) at 2660 A, wherein the corresponding primary or secondary unit 54; 50, 56 can provide 333.3 A by way of example. Thus, for a total current of 4000 A, 12 units 54; 50, 56 are required by way of example. Figure 6 , 7 or 8, in which case different topologies are conceivable.

[0041] according to Figure 6In the embodiment, six switchable units 50 (50.1, 50.2, ..., 50.6) and two secondary units 56 (constructed to be non-switchable) are provided, which are connected in parallel and are used to supply power to a consumer 40 consisting of a series circuit of at least two sub-consumers 40.1, 40.2. If the six switchable units 50 are now operated in the primary operation 21, 12 primary branches (two branches, including the AC / DC rectifier 16 connected in parallel and the converter 30 operated as an AC / DC rectifier) ​​are available. Therefore, there are two secondary units 56 in excess for the upper current range. These units can be used to reduce the maximum load of the individual units 50, 56. Alternatively, they can be turned off in the upper voltage range.

[0042] In accordance with Figure 7 In the embodiment of , four switchable units 50 (50.1, 50.2, ..., 50.4) and four secondary units 56 (designed to be non-switchable) are provided, which are connected in parallel and are used to supply power to the load 40 consisting of a series circuit of at least two sub-loads 40.1, 40.2. If the four switchable units 50 are operated in the primary operation 21, eight primary branches and four secondary units 56 or branches are available, and these branches and units work in the mixed operation.

[0043] This topology still allows savings to be achieved in terms of power electronics, since a total of 24 power cells (rectifiers 16 and DC voltage converters 30 ) are required for a complete equipment of 12 secondary cells 56 .

[0044] Optionally, according to Figure 5 In the design of , two secondary units 56 can be removed when the characteristic curve ages accordingly (characteristic curve 47 transforms into characteristic curve 48).

[0045] In accordance with Figure 8 In another embodiment, only the switchable unit 50 may be used instead. Figure 8 In the embodiment of , eight switchable units 50 (50.1, 50.2, ..., 50.8) are provided in parallel and are used to supply power to the electrical appliance 40. This embodiment is also characterized by the combination of the switchable unit 50 and the secondary unit, and in this embodiment, the secondary unit is also configured as the switchable unit 50.

[0046] The described circuit arrangement is particularly suitable for operating an electrolysis device 40 or comparable devices which, at high power, must be supplied with a DC voltage over a wide voltage range from an AC network.

Claims

1. A device for supplying a DC voltage to at least one electrical consumer (40), in particular an electrolysis device, comprising a plurality of switchable units (50) connected in parallel, wherein: The switchable units (50) each comprise at least one rectifier (16) and at least one converter (30), wherein in primary operation (21) the converter (30) can be operated in parallel with the rectifier (16) so that the converter (30) is used as a rectifier (30) to convert an AC voltage provided by a power source (12) into a DC voltage, wherein in secondary operation (23) the converter (30) can be operated as a DC voltage converter (30) connected downstream of the rectifier (16) to supply a voltage (U) to the electrical load (40), wherein at least one secondary unit (56) is provided, which is connected in parallel with the switchable unit (50).

2. The device according to claim 1, characterized in that The secondary unit is designed as a non-switchable unit (56) and / or as a switchable unit (50).

3. The device according to any one of the preceding claims, characterized in that At least one non-switchable unit (56) and at least one switchable unit (50) are provided.

4. The device according to any one of the preceding claims, characterized in that Several of the secondary units (56) and / or several of the switchable units (50) are selected in such a way that the characteristic curves (Pg2) generated by these units, in particular the current-voltage characteristic curve (Pg2), intersect the characteristic curve (66) of the electrical load (40), in particular the current-voltage characteristic curve (66), at a point above the limit voltage (Ug).

5. The device according to any one of the preceding claims, characterized in that A plurality of secondary units (56) and / or a plurality of switchable units (50) are selected such that the characteristic curves (Pg2), in particular the current-voltage characteristic curve (Pg2), generated by these units intersect the characteristic curve (66), in particular the current-voltage characteristic curve (66), of the electrical load (40) at a point to the right of a percentage, in particular 50%, of the maximum current (Imax).

6. The device according to any one of the preceding claims, characterized in that A plurality of secondary units (56) and / or a plurality of switchable units (50) are selected such that the intersection of the characteristic curve (66) with the voltage limit value (Ug) is at a current value (I) which is less than a percentage of the current value of the maximum current (Imax), in particular 50% (Imax / 2), and a plurality of secondary units (56) and / or a plurality of switchable units (50) are selected such that the characteristic curves (Pg2) generated by these units, in particular the current-voltage characteristic curve (Pg2), intersect the characteristic curve (66) of the electrical load (40), in particular the current-voltage characteristic curve (66), at a point above the limit voltage (Ug).

7. A device according to any one of the preceding claims, characterised in that The secondary unit (56) is operable in a wider voltage range than the primary unit (54).

8. The device according to any one of the preceding claims, characterized in that The primary unit (54) and / or the secondary unit (56) are designed to be switchable and detachable, in particular independently of one another.

9. The device according to any one of the preceding claims, characterized in that - at least one coil (14, 38) is arranged between the rectifier (16) and / or converter (30) of the switchable unit (50) and the power source (12), and / or - at least one switching device (41) of a switching unit is provided between the power source (12) and the converter (30), the switching unit being configured to switch between the primary operation (21) and the secondary operation (23), and / or - in particular at least one coil (38) is arranged for each phase, and / or - at least one switching element (42, 43) of the switching unit is arranged between the converter (30) and the load, in particular the electrolysis device (40), and / or At least one switch (42) of the switching unit is arranged between the further coil (38) and the input of the electrical load, in particular an electrolysis device (40).

10. The device according to any one of the preceding claims, characterized in that At least one switching unit (41, 42, 43) is provided, which: either connects the converter (30) in parallel with the rectifier (16) in primary operation (21), so that the converter (30) is used as a rectifier (30) to convert the AC voltage provided by the power source (12) into a DC voltage; or operates the converter (30) as a DC voltage converter (30) connected downstream of the rectifier (16) in secondary operation (23), wherein the output voltage of the converter (30) is used to supply power to the electrolysis device (40).

11. The device according to any one of the preceding claims, characterized in that The load (40) is designed as an electrolysis device and / or the load (40) comprises at least two sub-loads (40.1, 40.2) which are connected in series, in particular, each of which is a reactor of the electrolysis device.

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