Circuit arrangement for rectifying an alternating voltage into a direct voltage

Abstract

The invention relates to a circuit arrangement (100) for rectifying an alternating voltage into a direct voltage, comprising alternating voltage terminals (101) for receiving an alternating voltage; a transformer circuit (110) configured to convert the alternating voltage received at the alternating voltage terminals (101) into a second alternating voltage, in particular to reduce it, to change the voltage amplitude of the second alternating voltage to a predetermined value, and to provide the second alternating voltage with the voltage amplitude changed to the predetermined value as an output voltage; a rectifier circuit (150) configured to convert the output voltage provided by the transformer circuit (110) into a direct voltage; and direct voltage terminals (102) for providing the direct voltage generated by the rectifier circuit (150).

Description

[0001] The present invention relates to a circuit arrangement for rectifying an alternating voltage into a direct voltage, a method for rectifying an alternating voltage into a direct voltage, a computing unit, and a computer program for carrying it out. Background of the invention

[0002] To supply electrical power to consumers such as electrochemical plants, e.g., hydrogen production plants via electrolysis, it is usually necessary to provide electrical power in the form of direct current (DC) power. For this purpose, alternating current (AC) supplied by an AC grid can be rectified into a corresponding DC voltage. Depending on the plant's operating point, it may be necessary to adjust the current and voltage of this DC power. A full converter can be used for this purpose, for example, which completely rectifies the entire AC power supplied by the grid and adjusts the current and voltage amplitude accordingly.

[0003] Such a complete conversion can involve a high component count. An improved method for rectifying an AC voltage into a DC voltage would be desirable. Disclosure of the invention

[0004] According to the invention, a circuit arrangement for rectifying an alternating voltage into a direct voltage, a method for rectifying an alternating voltage into a direct voltage, a computing unit, and a computer program for carrying out this method are proposed, comprising the features of the independent claims. Advantageous embodiments are the subject of the dependent claims and the following description.

[0005] The advantages and embodiments of the circuit arrangement and the method according to the invention will become apparent from the present description in a corresponding manner.

[0006] The circuit arrangement includes AC voltage connections, a transformer circuit, a power electronics circuit for flexible voltage amplitude adjustment, a rectifier circuit, and DC voltage connections. The AC voltage connections are intended for receiving an AC voltage, for example, an AC voltage supplied by an AC power grid. For example, the received AC voltage can be a multi-phase voltage, such as a three-phase AC voltage.

[0007] The transformer circuit is designed to convert the alternating voltage received at the AC terminals into a second alternating voltage, specifically to reduce, step down, or increase it. Furthermore, the transformer circuit is designed to change, adjust, or set the amplitude of this second alternating voltage to a predetermined value or in a predetermined manner. The transformer circuit provides the second alternating voltage with its amplitude changed, adjusted, or set to the predetermined value as the output voltage.

[0008] The rectifier circuit is designed to convert the output voltage provided by the transformer circuit into a DC voltage. This DC voltage generated by the rectifier circuit is then made available at the DC terminals.

[0009] The present invention is based on the insight that, instead of a full conversion in which the entire supplied AC voltage power is converted, only a partial power conversion can be carried out by adjustments on the AC voltage side. For the efficient and safe operation of a load connected to the DC voltage terminals, e.g., an electrochemical plant, it is advantageously sufficient to convert only a corresponding portion of the AC voltage supplied at the AC voltage terminals and adapt it to an operating point of the load.

[0010] The power electronic circuit for flexible voltage adjustment makes it possible, in particular, to adapt the voltage at an electrochemical plant or at the electrochemical element during operation to the optimal operating point of the load.

[0011] A conventional full converter often has several stages, with the total power being converted by all these stages to achieve DC voltage adjustment. In contrast, according to the present invention, not all of the AC power supplied at the AC terminals is converted into DC power. Instead, the voltage amplitude on the AC side is adjusted, and the correspondingly adjusted AC voltage is converted into DC. Further adjustment of the DC voltage generated in this way is advantageously unnecessary. The DC voltage generated by the rectifier circuit can conveniently be supplied directly to a load connected to the DC terminals.

[0012] The number of components in the circuit arrangement can be reduced in this way. Furthermore, the efficiency of the circuit arrangement can be increased by using fewer or smaller components. The invention also enables low losses and low costs.

[0013] According to one embodiment, the transformer circuit comprises a transformer unit and an amplitude-modifying circuit. The transformer unit is configured to convert the AC voltage received at the AC terminals into a second AC voltage, in particular to reduce it. The amplitude-modifying circuit is configured to change the voltage amplitude of the second AC voltage to a predetermined value. The amplitude-modifying circuit can be provided on a high-voltage side and / or a low-voltage side of the transformer unit. Advantageously, the amplitude-modifying circuit includes mechanical and / or electronic switches, whereby the voltage amplitude can be changed by actuating these switches.

[0014] According to one embodiment, the amplitude-changing circuit is configured to change the number of turns in the transformer unit used for converting the AC voltage into the second AC voltage, particularly during operation of the circuit arrangement. The voltage amplitude of the second AC voltage is advantageously dependent on this number of turns in the transformer unit, and in particular directly proportional to the number of turns. Using the amplitude-changing circuit, the number of turns on an input and / or output side of the transformer unit can be advantageously changed in order to modify the voltage amplitude of the second AC voltage and adjust it to the specified value.

[0015] According to one embodiment, the amplitude-changing circuit is connected between the AC terminals and the transformer unit, i.e., on the input or high-voltage side of the transformer unit. The amplitude-changing circuit then includes a medium-voltage switching unit, which in particular comprises a switching element, especially a mechanical switching element. This medium-voltage switching unit is configured to electrically connect input-side windings of the transformer unit with different numbers of turns to the AC terminals, i.e., one of several such different numbers of turns. This medium-voltage switching unit allows the voltage amplitude on the high-voltage side to be adjusted to the specified value with minimal loss.The switching element of the medium-voltage switching unit can, in particular, be a mechanical switching element by means of which a specific number of turns can be selected and used for the AC voltage conversion. In this case, the transformer unit and the amplitude-changing circuit can, in particular, form a mechanical variable transformer.

[0016] According to one embodiment, the amplitude-modifying circuit is connected between the transformer unit and the rectifier circuit, i.e., on the output or low-voltage side of the transformer unit. In this case, the amplitude-modifying circuit includes a low-voltage switching unit, which in particular comprises at least one semiconductor switching element, especially at least one triac element or other suitable switching elements that exhibit reverse blocking capability. The low-voltage switching unit is configured to electrically connect output-side windings of the transformer unit with different or varying numbers of turns to the rectifier circuit, i.e., one of several such different or varying numbers of turns. The low-voltage switching unit advantageously allows the voltage amplitude to be adjusted to the predetermined value on the low-voltage side with minimal loss.By switching or controlling individual semiconductor switching elements of the low-voltage switching unit, a more appropriate number of turns can be selected and used for the AC voltage conversion.

[0017] According to one embodiment, the amplitude-modifying circuit is connected between the transformer unit and the rectifier circuit and includes a linear regulator circuit. This linear regulator circuit is advantageously connected in series with the rectifier circuit on the output or low-voltage side of the transformer unit. Advantageously, the linear regulator circuit includes switching elements, and the voltage amplitude can be varied accordingly by controlling these switching elements.

[0018] According to one embodiment, the linear regulator circuit comprises at least one controllable transformer unit or at least one control transformer, each (i.e., the single controllable transformer unit or each of them if more than one is present) comprising a transformer element and at least one semiconductor switching element, in particular at least one triac element or other suitable switching elements that have reverse blocking capability. In particular, four such semiconductor switching elements can be provided per AC voltage phase to control the respective transformer element. The respective transformer element can, in particular, be connected in a first connecting line to the rectifier circuit. The individual semiconductor switching elements can, in particular, be connected between terminals of the respective transformer element and a second connecting line to the rectifier circuit.In particular, several such controllable transformer units can be provided, which together can form a tap changer or stages of the linear regulator.

[0019] According to one embodiment, the linear regulator circuit comprises at least one active linear regulator unit, each (i.e., the single active linear regulator unit, or each of them if more than one is present) comprising a transformer element, a rectifier, and an inverter. The transformer element can, in particular, be connected in a first connecting line to the rectifier circuit. The rectifier and the inverter can be connected between the terminals of the transformer element and a second connecting line to the rectifier circuit.

[0020] According to one embodiment, the rectifier circuit comprises a half-bridge switch arrangement with at least one half-bridge. Each half-bridge expediently includes two semiconductor switching elements, e.g., diodes, field-effect transistors (FETs), metal-oxide-semiconductor field-effect transistors (MOSFETs), etc. Such half-bridges allow the adapted alternating voltage to be effectively rectified.

[0021] According to one embodiment, the specified value depends on a load that can be connected to the DC terminals, in particular on the load's operating point. The AC power supplied at the AC terminals can expediently be adjusted for subsequent rectification so that the rectified DC voltage is sufficient for efficient and safe operation of the connected load at the respective operating point.

[0022] According to one embodiment, the circuit arrangement is designed to be electrically connected to an electrochemical plant, particularly a hydrogen production plant, via its DC voltage connections, for the purpose of operating the electrochemical plant. The circuit arrangement is thus particularly suitable for supplying electrical power to a given electrochemical plant. Advantageously, the circuit arrangement is designed to convert a single-phase or multi-phase AC voltage from an AC power grid into a single-phase DC voltage sufficient for the efficient and safe operation of the electrochemical plant at a given operating point.

[0023] A computing unit according to the invention is, in particular in terms of programming, equipped to carry out a method according to the invention.

[0024] Implementing a method according to the invention in the form of a computer program or computer program product with program code for carrying out all method steps is also advantageous, as this incurs particularly low costs, especially if an executing control unit is already available for other tasks. Finally, a machine-readable storage medium is provided with a computer program stored on it as described above. Suitable storage media or data carriers for providing the computer program are, in particular, magnetic, optical, and electrical storage media, such as hard drives, flash memory, EEPROMs, DVDs, etc. Downloading a program via computer networks (Internet, intranet, etc.) is also possible. Such a download can be wired or wireless (e.g., via a WLAN network, a 3G, 4G, 5G, or 6G connection, etc.).

[0025] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.

[0026] The invention is schematically illustrated in the drawing using exemplary embodiments and is described below with reference to the drawing. Brief description of the drawings Fig. Figure 1 schematically shows an embodiment of a circuit arrangement according to the invention. Fig. Figure 2 schematically shows an embodiment of a circuit arrangement according to the invention. Fig. Figure 3 schematically shows an embodiment of a circuit arrangement according to the invention. Fig. Figure 4 schematically shows an embodiment of a circuit arrangement according to the invention. Fig. Figure 5 schematically shows an embodiment of a circuit arrangement according to the invention. embodiment(s) of the invention

[0027] In Fig. Figure 1 is a schematic embodiment of a circuit arrangement according to the invention, shown and labelled 100.

[0028] The circuit arrangement 100 is connected to an AC voltage network 103 via AC voltage connections 101 and to a consumer 104, for example an electrochemical plant, e.g. a plant for hydrogen production by means of electrolysis, via DC voltage connections 102.

[0029] The circuit arrangement 100 can be configured to convert a single-phase or multi-phase alternating voltage from the alternating voltage network 102 into a single-phase direct voltage sufficient for efficient and safe operation of the electrochemical plant 104 at one operating point.

[0030] For this purpose, the circuit arrangement 100 comprises a transformer circuit 110 and a rectifier circuit 150, wherein the transformer circuit 110 is configured to convert the alternating voltage received at the AC voltage terminals 101 into a second alternating voltage and to modify the voltage amplitude of the second alternating voltage to a predetermined value, this value being predetermined depending on an operating point of the system 104. This second alternating voltage with the voltage amplitude modified to the predetermined value is converted into a direct voltage by the rectifier circuit 150, and this direct voltage is provided at the DC voltage terminals 102 for supplying the system 104.

[0031] Furthermore, a control unit 105 is provided for this purpose in order to control the circuit arrangement 100 or electronic switching elements of the circuit arrangement 100 and to carry out an embodiment of a method according to the invention.

[0032] The circuit arrangement 100 converts the entire AC voltage power of the network 110 supplied at the AC voltage terminals 101. Additionally, the voltage amplitude is adjusted on the AC side, and the correspondingly adjusted AC voltage is converted into DC voltage. Further adjustment of the generated DC voltage is therefore not necessary.

[0033] The following will be discussed in relation to the Fig. Two to five different configurations of the circuit arrangement 100 are explained.

[0034] In Fig. Figure 2 is a schematic embodiment of the circuit arrangement according to the invention, designated by the letter 200. The circuit arrangement 200 has AC voltage connections 201, DC voltage connections 202, a transformer circuit 210, and a rectifier circuit 250. The electrochemical system 104 is in Fig. 2 is indicated purely schematically by a resistor and a battery.

[0035] The rectifier circuit 250 has a half-bridge switch arrangement with two half-bridges 251, each half-bridge 251 having two semiconductor switching elements 252. In the example shown, the semiconductor switching elements 252 are each configured as diodes, but other semiconductor switching elements can also be used, e.g., field-effect transistors (FETs), metal-oxide-semiconductor field-effect transistors (MOSFETs), etc.

[0036] The transformer circuit 210 comprises a transformer unit 211 and an amplitude-modifying circuit 212. The transformer unit 211 is configured to convert the alternating voltage received at the AC voltage terminals 201 into the second alternating voltage. The amplitude-modifying circuit 212 is configured to change the voltage amplitude of the second alternating voltage to the specified value. For this purpose, the amplitude-modifying circuit 212 is configured to change the number of turns of the transformer unit 211 used for converting the AC voltage into the second alternating voltage.

[0037] As in Fig. As shown in Figure 2, the amplitude-changing circuit 212 can be connected on an input or high-voltage side of the transformer unit 211 between the AC voltage terminals 201 and the transformer unit 211. In the example of Fig. 2 The amplitude-changing circuit 212 includes a medium-voltage switching unit 220 in the form of a mechanical switching element, which is configured to electrically connect input-side windings of the transformer unit 211, each with one of several different numbers of turns, to the AC voltage terminals 201. Since the voltage amplitude of the second AC voltage is conveniently directly proportional to the number of turns of the transformer unit 211, the voltage amplitude can be adjusted to the specified value by changing the number of turns using the mechanical switching element 220.

[0038] The amplitude-changing circuit can also be provided on an output or low-voltage side of the transformer unit, as shown below. Fig. 3 will be explained.

[0039] Also in Fig. Figure 3 schematically shows an embodiment of the circuit arrangement according to the invention and is designated 300. The circuit arrangement 300 also has AC voltage connections 301, DC voltage connections 302, a transformer circuit 310 and a rectifier circuit 350, wherein the rectifier circuit 350 has half-bridges 351 with semiconductor switching elements 352.

[0040] As in Fig. As shown in Figure 3, the transformer circuit 310 comprises a transformer unit 311 and an amplitude-modifying circuit 312 connected on the output or low-voltage side between the transformer unit 311 and the rectifier circuit 350. In the example shown in Figure 3, the amplitude-modifying circuit 312 has a transformer unit 311 and an amplitude-modifying circuit 312 connected between the transformer unit 311 and the rectifier circuit 350. Fig. 3 a low-voltage switching unit which has a plurality of semiconductor switching elements 320, e.g. three triac elements or other suitable semiconductor switches. By controlling these triac elements 320, output-side windings of the transformer unit with different numbers of turns are electrically connected to the rectifier circuit 350, whereby the voltage amplitude can be set to the specified value.

[0041] The amplitude-varying circuit can also be designed as a linear regulator circuit, as described below in relation to the Fig. 4 and Fig. 5 is explained

[0042] Fig. Figure 4 schematically shows an embodiment of the circuit arrangement 400 according to the invention. This circuit arrangement 400 also has AC voltage connections 401, DC voltage connections 402, a transformer circuit 410 and a rectifier circuit 450 comprising half-bridges 451 with semiconductor switching elements 452.

[0043] The transformer circuit 410 comprises a transformer unit 411 and an amplitude-varying circuit 412 designed as a linear regulator circuit. This linear regulator circuit 412, for example, comprises two controllable transformer units 420, each of which has a transformer element 421 and four semiconductor switching elements 422, e.g., in the form of triac elements.

[0044] The linear regulator circuit can also be designed, for example, as an active linear regulator unit, as described below in relation to Fig. 5 is explained

[0045] Also in Fig. Figure 5 is a schematic embodiment of the circuit arrangement 500 according to the invention, comprising AC voltage connections 501, DC voltage connections 502, a transformer circuit 510 and a rectifier circuit 550 comprising half-bridges 551 with semiconductor switching elements 552.

[0046] The transformer circuit 510 comprises a transformer unit 511 and an amplitude-varying circuit 512 designed as a linear regulator circuit, which is configured as an active linear regulator unit 520. This linear regulator unit 520 comprises a transformer element 521, a rectifier 522, and an inverter 523.

[0047] In the Fig.Figures 2 to 5 show the individual circuit arrangements 200, 300, 400, and 500, each as a single-phase schematic. It should be understood that circuit arrangements 200, 300, 400, and 500 can also be implemented as multi-phase solutions, for example, to convert a three-phase AC or three-phase voltage into a DC voltage.

Claims

[1] Circuit arrangement (100, 200, 300, 400, 500) for rectifying an alternating voltage into a direct voltage, comprising: AC voltage terminals (101, 201, 301, 401, 501) for receiving an AC voltage; a transformer circuit (110, 210, 310, 410, 510) which is configured to convert the alternating voltage received at the alternating voltage terminals (101, 201, 301, 401, 501) into a second alternating voltage, in particular to reduce it, to change a voltage amplitude of the second alternating voltage to a predetermined value and to provide the second alternating voltage with the voltage amplitude changed to the predetermined value as an output voltage; a rectifier circuit (150, 250, 350, 450, 550) configured to convert the output voltage provided by the transformer circuit (110, 210, 310, 410, 510) into a DC voltage; and DC voltage terminals (102, 202, 302, 402, 502) for providing the DC voltage generated by the rectifier circuit (150, 250, 350, 450, 550). [2] Circuit arrangement (100, 200, 300, 400, 500) according to claim 1, wherein the transformer circuit (110, 210, 310, 410, 510) comprises a transformer unit (211, 311, 411, 511) and an amplitude variation circuit (212, 312, 412, 512), wherein the transformer unit (211, 311, 411, 511) is configured to convert the alternating voltage received at the alternating voltage terminals (101, 201, 301, 401, 501) into the second alternating voltage, wherein the amplitude variation circuit (212, 312, 412, 512) is configured to change the voltage amplitude of the second alternating voltage to the predetermined value. [3] Circuit arrangement (100, 200, 300) according to claim 2, wherein the amplitude variation circuit (212, 312) is configured to change a number of turns of the transformer unit (211, 311) used for converting the alternating voltage into the second alternating voltage. [4] Circuit arrangement (100, 200) according to claim 3, wherein the amplitude variation circuit (212) is connected between the AC voltage terminals (201) and the transformer unit (211) and has a medium-voltage switching unit (220), in particular having a switching element, wherein the medium-voltage switching unit (220) is designed to electrically connect input-side windings of the transformer unit (211), each having one of a plurality of different numbers of windings, to the AC voltage terminals (201). [5] Circuit arrangement (100, 300) according to claim 2 or 3, wherein the amplitude variation circuit (312) is connected between the transformer unit (311) and the rectifier circuit (350) and has a low-voltage switching unit (320), in particular having at least one semiconductor switching element, in particular at least one triac element, wherein the low-voltage switching unit (320) is configured to electrically connect output-side windings of the transformer unit (311), each having one of a plurality of different numbers of windings, to the rectifier circuit (350). [6] Circuit arrangement (100, 400, 500) according to one of claims 2 to 5, wherein the amplitude variation circuit (412, 512) is connected between the transformer unit (411, 511) and the rectifier circuit (450, 550) and comprises a series regulator circuit. [7] Circuit arrangement (100, 400) according to claim 6, wherein the series regulator circuit (412) has at least one controllable transformer unit (420), each comprising a transformer element (421) and at least one semiconductor switching element (422), in particular at least one triac element. [8] Circuit arrangement (100, 500) according to claim 6 or 7, wherein the series regulator circuit (512) comprises at least one active series regulator unit (520), each comprising a transformer element (521), a rectifier (522) and an inverter (523). [9] Circuit arrangement (100, 200, 300, 400, 500) according to one of the preceding claims, wherein the rectifier circuit (150, 250, 350, 450, 550) comprises a half-bridge switch arrangement with at least one half-bridge (251, 351, 451, 551), wherein each half-bridge (251, 351, 451, 551) has two semiconductor switching elements (252, 352, 452, 552). [10] Circuit arrangement (100, 200, 300, 400, 500) according to one of the preceding claims, wherein the predetermined value is predetermined as a function of a consumer (104) connectable to the DC voltage terminals (102, 202, 302, 402, 502), in particular as a function of an operating point of the consumer (104). [11] Circuit arrangement (100, 200, 300, 400, 500) according to one of the preceding claims, which is designed to be electrically connected via the DC voltage connections (102, 202, 302, 402, 502) to an electrochemical plant (104) for the operation thereof, in particular to a plant for hydrogen production. [12] Method for rectifying an alternating voltage into a direct voltage by means of a circuit arrangement (100, 200, 300, 400, 500) according to one of the preceding claims, comprising: Controlling the transformer circuit (110, 210, 310, 410, 510) to convert the alternating voltage received at the alternating voltage terminals (101, 201, 301, 401, 501) into a second alternating voltage, in particular to reduce it, to change a voltage amplitude of the second alternating voltage to a predetermined value and to provide the second alternating voltage with the voltage amplitude changed to the predetermined value as an output voltage; Driving the rectifier circuit (150, 250, 350, 450, 550) to convert the output voltage provided by the transformer circuit (110, 210, 310, 410, 510) into a DC voltage. [13] Computing unit (105) which is configured to carry out all method steps of a method according to claim 12. [14] Computer program which causes a computing unit (105) to carry out all method steps of a method according to claim 12 when it is executed on the computing unit (105). [15] A machine-readable storage medium having stored thereon a computer program according to claim 14.

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