Arrangement and procedure for supplying a load from an energy supply source

Abstract

The invention relates to an arrangement (200) for supplying a load (150) with alternating voltage from a power supply source (130), wherein the arrangement comprises several active rectifiers (110, 120) connected in parallel and one or more transformers (160), wherein the several active rectifiers have DC-side connections (114, 124) for electrical connection to the load, wherein the several active rectifiers are electrically connectable to or are connected to the one or more transformers (160) on the AC-side, wherein separate secondary windings of the one or more transformers are assigned to different several active rectifiers, and wherein the one or more transformers have connections (166) for electrical connection to the power supply source (130). The invention also relates to a method and a system therefor.

Description

[0001] The present invention relates to an arrangement for supplying a load from an AC power source using a plurality of parallel-connected active rectifiers, a method therefor and a system comprising such an arrangement. Background of the invention

[0002] For various applications, such as operating electrolyzers, powerful power sources or energy supply sources are required. The energy supply source can be, for example, a grid connection. Disclosure of the invention

[0003] According to the invention, an arrangement for supplying a load from a power source, a method therefor, and a system comprising such an arrangement are proposed, having the features of the independent patent claims. Advantageous embodiments are the subject of the dependent claims and the following description.

[0004] The invention concerns the supply of alternating current to a load from an energy source, e.g., one or more electrolyzers. Electrolyzers can be used to extract hydrogen (and oxygen) from water, for example, and then temporarily store it or make it available for further use.

[0005] A power supply source, for example, could be a mains connection or, more generally, a power or voltage network. Especially for industrial-scale applications, powerful power sources or power supply sources are required. In conventional technology, the rectifiers used for this purpose, which convert the AC voltage of the power supply into a DC voltage for the load, can be constructed using thyristors. However, this has the disadvantage that severe grid disturbances can occur due to the required phase control.

[0006] When active rectifiers, e.g., with so-called B6 bridges, are used, high-performance switches (power switches) such as IGBTs, MOSFETs, or other semiconductor switches are generally required. Since the size of power switches is limited, power switches or active rectifiers in general can be connected in parallel. However, this can result in circulating currents between the rectifiers.

[0007] A circulating current occurs in particular when, in two rectifiers connected in parallel, a high-side switch is closed in one rectifier and a low-side switch is closed in the other rectifier in the same phase. This creates a current path via which, for example, the intermediate circuit capacitor can be discharged. There are various reasons why such a switching state can occur. For example, the control signals (in particular the underlying so-called carrier signals) of the two rectifiers can be offset from one another, or the duty cycles of the two rectifiers can be different. Component tolerances in the rectifiers can also cause a time offset in the control edges.

[0008] Although such circulating currents can be avoided or at least reduced by targeted control and regulation methods (e.g. specific control patterns for the power switches of the rectifiers), such control and regulation methods are usually complex to implement.

[0009] Within the scope of the present invention, however, a special topology is now proposed which can prevent circulating currents even without adapting the control. To supply a load with alternating voltage from a power supply source, several active rectifiers connected in parallel are used here too. However, one or more transformers are also used. The several active rectifiers are, as usual, electrically connected to the load on the DC side and electrically connected to the power supply source on the AC side via the one or more transformers. Different ones of the several active rectifiers are each assigned separate secondary windings of the one or more transformers. In particular, the different secondary windings assigned to the several active rectifiers are galvanically isolated from one another.

[0010] In this way, the phases or phase connections of the various active rectifiers are galvanically isolated from each other, so that circulating currents cannot occur even in the case of the above-mentioned deviations in the control signals or control patterns.

[0011] It should be noted here that when we talk about active rectifiers, we can also generally refer to power converters, but they can also be operated as rectifiers; for example, a power converter can also be operated as a rectifier and as an inverter. Inverters are often also referred to as inverters.

[0012] In one embodiment, the energy supply source has multiple phases, e.g. three phases, as is often the case with high-performance AC voltage networks. The one or more transformers have a total of multiple primary windings and multiple secondary windings, with one of the primary windings being assigned to each of the multiple phases of the energy supply source. In the case of three phases, there are therefore three primary windings. One of the secondary windings is assigned to each AC-side phase connection of the multiple active rectifiers. This means that the number of secondary windings corresponds to the number of single-phase rectifiers (half-bridge) or the product of the number of phases of the energy supply source and the number of active multi-phase rectifiers.Each rectifier has a number of half-bridges (often referred to as phases) equal to the number of phases of the power source. For example, in the case of two active three-phase rectifiers, there are six secondary windings.

[0013] Each of the primary windings is assigned the secondary windings of the corresponding phase connections (or phases) of the multiple active rectifiers. In the case of, for example, two active rectifiers, each primary winding is assigned two secondary windings. The multiple active rectifiers are electrically connected on the AC side via their phase connections to the respective associated secondary winding, and the primary windings are each electrically connected to the associated phase of the multiple power source.

[0014] In this way, a parallel connection of several active rectifiers can easily be used in a multi-phase power supply without the risk of circulating currents.

[0015] In one embodiment, the primary windings and / or the secondary windings associated with each active rectifier each have a polygonal or star winding pattern. In the case of three phases, the polygonal winding pattern would be a delta winding pattern, for example. Thus, each winding is connected at one terminal or end to the respective phase (be it from the power supply or the phase terminal of the active rectifier), and at the other terminal or end to another winding or a neutral point.

[0016] In one embodiment, several separate transformers are used, with at least one of the several phases of the power supply source being assigned to exactly one of the several separate transformers. It is also conceivable for each phase to be assigned a transformer. In this case, for example, each transformer is assigned a primary winding and a secondary winding for each active rectifier.

[0017] It should be noted that the principle also works with a single-phase power supply. In this case, there is a primary winding, which is connected with both terminals or both ends to the - then two - lines of one phase of the power supply. Each active rectifier then has one or two half-bridges. In the case of a half-bridge, only the positive or only the negative half-wave can be rectified. In the case of two half-bridges, these two or their center taps are connected to the two terminals or ends of the then single secondary winding per rectifier, and the negative and positive half-waves can be rectified.

[0018] In one embodiment, the multiple active rectifiers are each electrically connected to the load on the DC side via a DC-DC converter, i.e., not directly. This then represents a two-stage topology, with which, for example, the DC voltage can be further adjusted in a targeted manner. Regardless of the use of DC-DC converters, however, an intermediate circuit capacitor can also be provided on the DC side, as already mentioned.

[0019] In one embodiment, at least three active rectifiers connected in parallel are used; more than three, e.g., four, five, or six active rectifiers connected in parallel are also conceivable. While in typical use without transformers, the risk of circulating currents increases with the number of rectifiers, this is not the case with the proposed topology. The number of active rectifiers connected in parallel can therefore be safely increased.

[0020] In one embodiment, at least two of the multiple active rectifiers are controlled with offset control patterns for rectification. While this is precisely what should be avoided in typical use without transformers due to the resulting circulating currents, this can be used specifically in the proposed topology, as it allows so-called harmonics (unwanted oscillations) on the primary side of the transformers to be avoided or at least reduced.

[0021] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0022] The invention is illustrated schematically in the drawing using exemplary embodiments and is described below with reference to the drawing. Short description of the drawings Fig. 1 schematically shows an arrangement for explaining a background of the invention. Fig. 2 shows schematically an arrangement according to the invention in a preferred embodiment. Embodiment(s) of the invention

[0023] In Fig. Figure 1 schematically shows an arrangement 100 for explaining a background of the invention. The arrangement 100 comprises, for example, two active rectifiers 110, 120 connected in parallel. The arrangement 100 serves to supply a load 150, e.g., one or more electrolyzers, with alternating voltage from a power supply source 130. For example, the power supply source 130 comprises three phases 130a, 130b, 130c.

[0024] The rectifier 110 has three half-bridges 110a, 110b, 110c, corresponding to the three phases of the power supply source 130, which can also be referred to as phases. Each half-bridge has, for example, two power semiconductor switches, a high-side switch T H and a low-side switch T L .

[0025] The rectifier 120 has three half-bridges 120a, 120b, 120c, corresponding to the three phases of the power supply source 130, which can also be referred to as phases. Each half-bridge has, for example, two power semiconductor switches, a high-side switch T H and a low-side switch T L .

[0026] Rectifiers 110 and 120 can therefore be constructed similarly. An alternating voltage can be rectified by the power semiconductor switches, which can be controlled, for example, by a control unit 142 using a control pattern to open and close (separate control units for the rectifiers are also conceivable); these are thus active rectifiers. In particular, however, rectifiers 110 and 120 are connected in parallel on the DC voltage side and can be electrically connected to load 150. In addition, an intermediate circuit capacitor 140 can be interposed. For this purpose, rectifiers 110 and 120 have terminals 114 and 124, respectively, on the DC voltage side, by means of which they can be connected to load 150.

[0027] On the AC side, however, the rectifiers 110 can be electrically connected to the power supply source 130. In particular, the corresponding phases are connected, ie, the phases or half-bridges 110a and 120a are connected to phase 130a. The same applies to the half-bridges 110b and 120b or 110c and 120c as well as the phases 130b and 130c. Suitable phase connections 112, 122 of the rectifiers 110, 120 are provided for this purpose. These phase connections are connected in the respective rectifier to the center taps of the respective half-bridges, ie, between the high-side switch T H and low-side switch T L . After the phase connections 122 and 122, inductors 116, 126 are provided as examples.

[0028] In this arrangement 100, the mentioned circulating currents can occur. For example, the high-side switch T Hthe half-bridge 110a of the rectifier 110 and the low-side switch T L the half-bridge 120a of the rectifier 120 must be closed, ie conductive, at the same time; this can also be the case only for a short time. In this case, a circulating current I K which can discharge the intermediate circuit capacitor 140.

[0029] In Fig. 2 schematically shows an arrangement 200 according to the invention in a preferred embodiment, with which a method according to the invention can also be carried out.

[0030] The arrangement 200 comprises, for example, two active rectifiers 110, 120 connected in parallel. The arrangement 200 serves to supply a load 150, e.g., one or more electrolyzers, with alternating voltage from a power supply source 130. For example, the power supply source 130 comprises three phases 130a, 130b, 130c. The arrangement 200 also comprises a transformer 160.

[0031] The two active rectifiers 110, 120 correspond to those according to Fig. 1, so reference can be made to the description therein. The same applies to the load 150, the power supply source 130, as well as the intermediate circuit capacitor 140 and the control unit 142.

[0032] As already mentioned, more than two active rectifiers, such as three or four, can also be used in parallel. Furthermore, a DC-DC converter (not shown here) can be connected between the active rectifiers and the load on the DC side.

[0033] The transformer 160 has, for example, three primary windings 162a, 162b, 162c, each of the three primary windings being assigned to one of the three phases of the power supply source 130. In addition, the transformer 160 has a total of six secondary windings, corresponding to the three primary windings and the two active rectifiers 110, 120.

[0034] Each phase or half-bridge of the active rectifier is assigned a secondary winding. Secondary winding 164.1a is assigned to phase or half-bridge 110a, secondary winding 164.1b to phase or half-bridge 110b, and secondary winding 164.1c to phase or half-bridge 110c. Similarly, secondary winding 164.2a is assigned to phase or half-bridge 120a, secondary winding 164.2b to phase or half-bridge 120b, and secondary winding 164.2c to phase or half-bridge 120c.

[0035] For this purpose, the phase terminals 112, 122 of the rectifiers can be electrically connected to the respective secondary windings.

[0036] In addition, the secondary windings of the corresponding phase connections of the multiple active rectifiers are assigned to each of the primary windings. In this specific case, the secondary windings 164.1a and 164.2a are assigned to primary winding 162a, the secondary windings 164.1b and 164.2b are assigned to primary winding 162b, and the secondary windings 164.1c and 164.2c are assigned to primary winding 162c.

[0037] Furthermore, the secondary windings are connected to each other according to a star winding pattern, for example, at the ends other than the ends at which they are connected to the phase terminals shown, for each rectifier to which they are assigned. The invention is also applicable when using a different connection—e.g., delta or zigzag.

[0038] The primary windings can, in turn, be electrically connected to the associated one of the multiple phases of the power supply source 130 via a respective terminal 166 (shown only for one primary winding). Furthermore, the primary windings are connected to one another at the ends other than the terminals 166 shown, for example, according to a star winding pattern. Delta or zigzag connections are also possible here.

[0039] The transformer 160, a single transformer in the example shown, can be configured, for example, to accommodate the primary windings and the secondary windings, in particular such that they are associated with one another as mentioned. For example, the transformer 160 can have three yokes, each of which has a primary winding and two secondary windings mounted on it. As mentioned, however, separate transformers can also be used.

[0040] By galvanically isolating the windings, especially the respective secondary windings, the Fig. 1 mentioned circulating currents do not occur here.

Claims

[1] Arrangement (200) for supplying a load (150) from a power supply source (130) with alternating voltage, the arrangement comprising a plurality of parallel-connected active rectifiers (110, 120) and one or more transformers (160), wherein the plurality of active rectifiers have DC side terminals (114, 124) for electrical connection to the load, wherein the plurality of active rectifiers are electrically connectable or connected on the AC voltage side to the one or more transformers (160), wherein different ones of the plurality of active rectifiers are each assigned separate secondary windings of the one or more transformers, and wherein the one or more transformers have terminals (166) for electrically connecting to the power supply source (130). [2] Arrangement (200) according to claim 1, wherein the power supply source (130) has a plurality of phases (130a, 130b, 130c), wherein one of the plurality of transformers comprises a total of a plurality of primary windings and a plurality of secondary windings, wherein each of the plurality of phases of the power supply source is assigned one of the primary windings, wherein each AC-side phase connection of the plurality of active rectifiers is assigned one of the secondary windings, wherein each of the primary windings is assigned the secondary windings of the corresponding phase terminals of the plurality of active rectifiers, wherein the plurality of active rectifiers are or can be electrically connected to the respective associated secondary winding via the phase terminals on the AC voltage side, and wherein the primary windings each have a terminal for electrical connection to the associated one of the plurality of phases of the power supply source. [3] Arrangement (200) according to claim 2, wherein a plurality of separate transformers are provided, and wherein at least one of the plurality of phases of the power supply source is assigned to exactly one of the plurality of separate transformers. [4] Arrangement (200) according to claim 2 or 3, wherein the primary windings and / or the secondary windings (164.1a, 164.2a, 164.1b, 164.2b, 164.1c, 164.2c) each associated with an active rectifier each have a polygonal or a star winding pattern. [5] Arrangement (200) according to one of the preceding claims, wherein the plurality of active rectifiers are each electrically connected to the load on the DC voltage side via a DC-DC converter. [6] Arrangement (200) according to one of the preceding claims, with at least three active rectifiers connected in parallel. [7] Arrangement (200) according to one of the preceding claims, wherein the various secondary windings associated with the plurality of active rectifiers are galvanically isolated from one another. [8] Arrangement (200) according to one of the preceding claims, wherein the load (150) comprises one or more electrolyzers. [9] Arrangement (200) according to one of the preceding claims, which is arranged such that at least two of the plurality of active rectifiers are controlled with mutually offset control patterns for rectification. [10] Method for supplying a load (150) from a power supply source (130) with alternating voltage, using a plurality of parallel-connected active rectifiers (110, 120) and one or more transformers (160), wherein the plurality of active rectifiers (110, 120) are electrically connected to the load (150) on the DC voltage side, wherein the plurality of active rectifiers are electrically connected on the AC voltage side to the energy supply source (130) via the one or more transformers (160), wherein different ones of the plurality of active rectifiers are each assigned separate secondary windings (164.1a, 164.2a, 164.1b, 164.2b, 164.1c, 164.2c) of the one or more transformers. [11] The method of claim 10, wherein the power supply source (130) has a plurality of phases (130a, 130b, 130c), wherein the one or more transformers have a total of several primary windings (162a, 162b, 162c) and several secondary windings (164.1a, 164.2a, 164.1b, 164.2b, 164.1c, 164.2c), wherein each of the several phases of the power supply source is assigned one of the primary windings, wherein each AC-side phase connection (112, 122) of the plurality of active rectifiers is assigned one of the secondary windings, wherein each of the primary windings is assigned the secondary windings of the corresponding phase terminals (112, 122) of the plurality of active rectifiers, wherein the plurality of active rectifiers are electrically connected on the AC side to the phase terminals with the respective associated secondary winding, and wherein the primary windings are each electrically connected to the associated one of the plurality of phases of the power supply source (130). [12] A system comprising one or more electrolyzers and an arrangement (200) according to claim 1 or 2, wherein the one or more electrolyzers are electrically connected as a load (150) to the DC-side terminals (114, 124).

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