Bridge circuit and energy conversion installation

Abstract

The protection relates to a bridge circuit (10) for providing an alternating current at a phase connection, comprising a first direct voltage connection (DC +) and a second direct voltage connection (DC-) for connecting a direct current source or a direct current load, an intermediate circuit (17), and a bridge (11) having a bridge switch, which is designed to connect the direct current source or the direct current load to the intermediate circuit (17). A potential applied to the DC voltage attachment terminals (DC +, DC-) is provided at the first bridge output (18a) and at the second bridge output (18b) independently of one another in a beat-controlled manner. A first connection path (15a) and a second connection path (15b) extend between the respective bridge output (18a, 18b) and the phase attachment end (AC), each of the connection paths (15a, 15b) having a filter choke (12a, 12b) on the bridge output side, the filter chokes (12a, 12b) of the connection paths (15a, 15b) being magnetically coupled to each other. A separating relay (13) having a plurality of relay contacts (14, 14a, 14b) is arranged between the bridge output (18a, 18b) and the phase attachment end (AC) in such a way that, in separate sections of the connection paths (15a, 15b), at least one of the relay contacts (14, 14a, 14b) is arranged in each of the connection paths (15a, 15b). The invention further relates to an energy conversion system comprising such a bridge circuit (10).

Description

Technical Field

[0001] The invention relates to a bridge circuit for providing an alternating current at phase attachment terminals and an energy conversion installation having such a bridge circuit. Background Art

[0002] When converting direct current into alternating current or converting alternating current into direct current, bridge modules are used, in which the potential applied to the direct voltage attachment terminal of the bridge module is provided at the phase attachment terminal of the bridge module in a clocked manner (getaktet) by semiconductor switches. It is desirable here that in addition to the positive and negative potentials of the direct current attachment terminal, further intermediate potentials can be provided, which can be formed at the direct voltage attachment terminal, for example, by a split intermediate circuit. However, it is also known to generate intermediate potentials in the bridge module, for example by means of a so-called flying capacitor (Flying Capacitor) topology. The more intermediate potentials that can be provided at the output attachment terminal of the bridge module, the smaller, lighter and therefore more cost-effective the filter connected downstream of the bridge module can be constructed.

[0003] Furthermore, from document DE 10 2012 107 122 A1 a bridge circuit for providing an alternating current at a phase connection is known, wherein an additional intermediate potential can be generated via a filter connected downstream of the bridge module, in that the bridge module has two bridge outputs which are clocked in an offset manner, and the filter has two magnetically coupled filter chokes in the corresponding connection paths, via which the two bridge outputs are connected to the common phase connection. In this way, the inverter can be manufactured with a high power density and a low weight, which is mainly determined by the weight of the filter. Similar topologies are also disclosed in documents DE 10 2016 222 001 A1 and EP 2136 465 A1, which have filter chokes in separate connection paths between a plurality of bridge outputs and a common phase output, wherein the filter chokes are also not magnetically coupled.

[0004] The following problem exists here: With high inverter or rectifier powers, the currents supplied by the bridge modules are high, and the disconnecting relays required by safety regulations need to be designed according to the maximum current flowing, which disconnecting relays disconnect the current flow from the bridge module via two relay contacts that can be actuated independently of one another. This leads to considerable costs and to a high additional weight, since large relays are excessively heavy compared to small relays. Summary of the invention

[0005] It is therefore an object of the present invention to provide a bridge circuit for supplying or receiving an alternating current at a phase connection or an energy conversion arrangement having a reduced material expenditure.

[0006] This object is achieved by a bridge circuit having the features of independent claim 1. Further embodiments are described with the features of the dependent claims. Claim 11 is directed to an energy conversion system having such a bridge circuit.

[0007] The bridge circuit according to the invention is used to provide an alternating current on phase-attached terminals and comprises:

[0008] - a first DC voltage attachment terminal and a second DC voltage attachment terminal, for attaching a DC power source or a DC load,

[0009] - Intermediate circuit,

[0010] a bridge having a bridge switch, which is designed to provide the potential present at the first DC voltage connection and the second DC voltage connection independently of one another in a clocked manner at a first bridge output and a second bridge output,

[0011] wherein the first connection path extends between the first bridge output terminal and the phase attachment terminal, and the second connection path extends between the second bridge output terminal and the phase attachment terminal,

[0012] Each of the connection paths has a filter choke on the bridge output side, and the filter chokes of the connection paths are magnetically coupled to each other.

[0013] Therein, a disconnecting relay having a plurality of relay contacts is arranged between the bridge output and the phase connection in such a way that in separate sections of the connecting paths at least one of the relay contacts is arranged in each of the connecting paths.

[0014] The clocking of the bridge circuit is hereby carried out in an offset manner with a phase shift to the carriers of the two bridge outputs, the phase shift typically being half or a quarter of the switching period. This makes it possible to provide a further potential at the phase connection in addition to the potential of the bridge outputs, the value of which lies between the current values ​​of the potential of the bridge outputs. As a result, the bridge circuit can be operated with lower losses and / or the network filter of the bridge circuit can be designed more cost-effectively.

[0015] In a preferred embodiment, the bridge is set up and designed to provide, at each of the bridge outputs, in addition to the potential applied to the first DC voltage attachment terminal and the potential applied to the second DC voltage attachment terminal, a third potential level formed by the potential of the DC voltage attachment terminal is provided. This potential can be formed by a split intermediate circuit and can be intercepted at the midpoint of the split intermediate circuit. However, it is also conceivable that the third potential is formed by a capacitor (so-called flying capacitor) arranged between the bridge switches of the bridge, which can be used to make the potential applied to one of the bridge outputs relative to one of the potentials of the DC voltage output terminal perform a voltage offset. Similarly, other potential levels can be formed by a plurality of split intermediate circuits or a combination of split intermediate circuits and flying capacitor bridges, and the other potential levels can be provided at the bridge output by suitable clocking control of the bridge switch. Thus, for example, in one embodiment, the bridge can be set up and designed to provide five potential levels formed by the potential of the DC voltage attachment terminal at each of the bridge outputs.

[0016] Since the current is distributed substantially evenly to the connection paths during operation of the bridge circuit by means of the known symmetrical regulation for the bridge current, the current load of the relay contacts of the disconnecting relay is halved, so that a more cost-effective and lighter relay type can be used as a disconnecting relay. Preferably, the distributed relay contacts of the disconnecting relay are located in different relay housings, so that each relay contact can be better cooled, which further reduces the required installation space. In contrast, the additional costs and additional weight caused by the additional voltage measurement on the capacitors 16a and 16b and possibly 46a and 46b can be ignored.

[0017] If there is an electrical (galvanisch) separation plane on the DC side or AC side of the bridge circuit, for example an electrical separation plane formed by a transformer, additional relay contacts can be omitted. Otherwise, safety standards require that two relay contacts of a separation relay that can be operated independently of each other are arranged in series between each of the bridge outputs and the phase attachment end. In a preferred embodiment, in this case, two relay contacts are arranged in separate sections of the connection path. As a result, each relay contact only needs to be designed according to the maximum current flowing in the corresponding connection path. An application example for a bridge circuit that does not have two serial relay contacts is a DC charging device for electric vehicles, in which such an electrical separation plane is usually present.

[0018] In another embodiment, the common relay contact of the disconnecting relay is arranged in a common section of the first connection path and the second connection path. Thus, although the common relay contact is loaded with the entire phase current, on the other hand, even if the two connection paths are separated from the phase connection by the opened relay contact, an electrical variable, such as a voltage or a current, can be detected in the common section of the first connection path and the second connection path by means of a common measuring device at the location between the serial relay contacts of the two connection paths.

[0019] Alternatively or additionally, a further filter comprising a further filter choke and a further filter capacitor may be arranged in a common section of the first connecting path and the second connecting path, wherein the common relay contact of the isolating relay is arranged between the further filter and the phase connection.

[0020] In order to effectively suppress the non-network frequency components of the supplied AC current, preferably, in each of the connection paths, a filter capacitor is respectively attached between the filter choke and the isolating relay, and the filter capacitor is connected to the first DC voltage attachment terminal, the second DC voltage attachment terminal or the midpoint by means of another attachment terminal. Here, the connection to the midpoint has the advantage of a lower voltage load of the filter capacitor.

[0021] A further suppression of non-network-frequency components of the supplied or received alternating current can be achieved by arranging a second filter between the filter choke and the disconnecting relay in at least one of the first and second connecting paths, preferably in both connecting paths, which second filter comprises a second filter choke and a second filter capacitor. This results in a so-called LCLC filter.

[0022] In this case, a DC source or a DC load can also be connected via a further power electronic converter which, for example, steps up or down the DC voltage.

[0023] In another aspect of the present invention, the energy conversion facility comprises a bridge circuit according to the present invention. Here, the energy conversion facility can be attached to the AC voltage network in a single-phase or multi-phase manner. In the case of multi-phase attachment, a bridge circuit according to the present invention can be provided for each of the phases. Preferably, the energy conversion facility has a photovoltaic generator or a battery as a DC power source for providing the converted AC current. However, in addition to or instead of a DC power source, the energy conversion facility may also have a DC load or be set up for attaching such a load. For example, the energy conversion facility may be a DC charging device for an electric vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention is illustrated below with the aid of the accompanying drawings, in which:

[0025] Figure 1 A first embodiment according to the invention of a bridge circuit is shown,

[0026] Figure 2 A second embodiment according to the invention of a bridge circuit is shown,

[0027] Figure 3 A third embodiment according to the invention of a bridge circuit is shown,

[0028] Figure 4 A fourth embodiment according to the invention of a bridge circuit is shown,

[0029] Figure 5 A fifth embodiment according to the invention of a bridge circuit is shown,

[0030] Figure 6 An embodiment according to the invention of an energy conversion facility is shown,

[0031] Figure 7a A first configuration of a bridge in a bridge circuit according to the invention is shown,

[0032] Figure 7b A second configuration of a bridge in a bridge circuit according to the invention is shown,

[0033] Figure 7c A third configuration of a bridge in a bridge circuit according to the invention is shown,

[0034] Figure 7d A fourth configuration of a bridge in a bridge circuit according to the invention is shown,

[0035] Figure 7e A fifth configuration of a bridge in a bridge circuit according to the invention is shown,

[0036] Figure 7f shows a sixth configuration of a bridge in a bridge circuit according to the invention,

[0037] Figure 7g shows a seventh configuration of a bridge in a bridge circuit according to the invention,

[0038] Figure 7h An eighth configuration of a bridge in a bridge circuit according to the invention is shown,

[0039] Figure 7i shows a ninth configuration of a bridge in a bridge circuit according to the invention,

[0040] Figure 7j shows a tenth configuration of a bridge in a bridge circuit according to the invention, and

[0041] Figure 7k An eleventh embodiment of a bridge in a bridge circuit according to the invention is shown. DETAILED DESCRIPTION

[0042] Figure 1 An embodiment according to the invention of a bridge circuit 10 is shown, which has DC voltage attachment terminals DC+, DC-, to which a DC source or a DC load can be attached. An intermediate circuit in the form of two intermediate circuit capacitors 17 is arranged between the DC voltage attachment terminals DC+, DC-, the midpoint M of which together with the DC voltage attachment terminals DC+, DC- supplies a DC voltage to a bridge 11. The bridge 11 has two bridge output terminals 18a, 18b, at which the bridge 11 supplies a voltage independently of one another in a clocked manner, said voltage being formed by a DC voltage.

[0043] The connection path 15a extends from the first bridge output 18a to the phase connection AC of the bridge circuit 10, in which the first filter choke 12a is arranged on the bridge output side and the relay contact 14a of the disconnecting relay 13 is arranged on the phase connection side. A first filter capacitor 16a branches out between the first filter choke 12a and the disconnecting relay 13, which is connected to the midpoint M. The second connection path 15b is constructed in a similar manner and extends from the bridge output 18b to the phase connection AC of the bridge circuit 10, in which the second filter choke 12b is arranged on the bridge output side and the further relay contact 14b of the disconnecting relay 13 is arranged on the phase connection side. A second filter capacitor 16b branches out between the second filter choke 12b and the disconnecting relay 13, which is likewise connected to the midpoint M. Alternatively, the filter capacitors 16 a , 16 b may also be connected to one of the DC voltage attachment terminals DC+, DC−.

[0044] The first filter choke 12a and the second filter choke 12b are magnetically coupled to each other, in particular, the first filter choke and the second filter choke have a common core. Since relay contacts 14a, 14b are arranged in each of the connection paths 15a, 15b, the separation relay 13 can be designed in terms of its current loadability only according to the maximum current that can flow in the corresponding connection paths 15a, 15b. As a result, the separation relay 13 can be configured cost-effectively. However, it is also conceivable that each relay contact in the relay contacts 14a, 14b is formed by two serial contacts, and for safety reasons, the contacts can be operated separately from each other, that is, for example, assigned to different relays. However, as mentioned above, for example, when an electrically isolated plane is connected upstream or downstream of the bridge circuit, a single relay contact can also meet the safety standards applicable in each connection path. This also applies to the implementation described below.

[0045] Figure 2 The bridge circuit 10 shown in FIG. Figure 1 The difference of the circuit shown in is that, on the one hand, the separation relay 13 now has only three relay contacts 14, one of which is arranged in a common section of the connection paths 15a, 15b, while the other relay contacts 14 are arranged in sections of the connection paths 15a, 15b that extend separately from each other. Thus, although the relay contacts 14 arranged in the common section of the connection paths 15a, 15b need to be designed according to the maximum current on the phase attachment end AC, this can only achieve a partial saving. However, at the same time, this arrangement of the relay contacts 14 can achieve that the electrical parameters, such as voltage, between the serial arrangements of the relay contacts 14 are detected by means of the same measuring device, so that the measuring device can be saved if necessary. In the case of a functional check of the relay contacts, this detection may be required in the case of a synchronization process of the AC voltage provided by the bridge circuit before being connected to the AC voltage network attached to the phase attachment end, or also during the normal feed-in operation of the bridge circuit.

[0046] Figure 3 The bridge circuit 10 has Figure 2 , wherein, in addition, a further filter is arranged in the common section of the connection paths 15a, 15b between the serial relay contacts 14. The further filter has a further filter choke 32 and a further filter capacitor 36, which is also connected to the midpoint M.

[0047] Figure 4 The bridge circuit 10 is also adopted as follows Figure 1, the arrangement of the relay contacts 14 shown in FIG. 1 , wherein, in addition, in each of the connection paths 15a, 15b, a second filter is arranged between the magnetically coupled filter chokes 12a, 12b and the disconnecting relay 13. In the first connection path 15a, the second filter is formed by the second filter choke 42a and the second filter capacitor 46a. In the second connection path 15b, the second filter is formed by the second filter choke 42b and the second filter capacitor 46b. The second filter chokes 42a, 42b of the first connection path 15a and the second connection path 15b are shown here as non-magnetically coupled, but the second filter chokes can also be magnetically coupled to each other. The additional filter is particularly effective in suppressing the non-network frequency components of the alternating current provided by the bridge circuit 10. In particular, when the bridge circuit is used in a three-phase inverter or rectifier, the connection of the filter capacitors 46a and 46b to the midpoint M can be omitted.

[0048] like Figure 5 As shown in Figure 3 Based on the embodiment of the bridge circuit 10 in , the second filter having the second filter choke 42a, 42b and the second filter capacitor 46a, 46b can also be easily combined with a further filter having a further filter choke 32 and a further filter capacitor 36 in each of the connection paths 15a, 15b in order to further amplify the filtering effect on the non-network frequency components of the supplied alternating current.

[0049] Additionally, in Figure 5An electrical separation plane 50 is drawn in, which is, for example, a transformer, which is arranged in a common section of the first connection path and the second connection path. This creates the possibility of meeting possible safety requirements in terms of separation from the attached network without having to provide two serial relay contacts of the separation relay 13 in each of the connection paths, which can be operated independently of each other. Instead, in each of the connection paths 15a, 15b, a single relay contact 14 is sufficient. Instead of the arrangement of the electrical separation plane 50 on the AC side, the arrangement on the DC side can also meet safety requirements, for example, by connecting an electrically separated DC / DC converter (not shown) upstream of the bridge circuit 10, without serial relay contacts. Similarly, other embodiments can also be configured in a safe and compliant manner by providing an electrical separation plane 50 with a single relay contact in each of the connection paths 15a, 15b. For example, a DC charging device for electric vehicles is an example in which an electrical separation between the network and the DC voltage connection is usually required even with a closed disconnect relay. In this case, a single relay contact 14 in each of the connection paths 15a, 15b is sufficient to meet the safety requirements.

[0050] Figure 6 1 shows an energy conversion facility based on a bridge circuit 10 according to the invention for feeding an alternating current in a single phase into an alternating voltage network 61 attached to the energy conversion facility. The structure of the bridge circuit 10 corresponds to Figure 1 The embodiment shown in the figure, however, the structure can also be designed according to other embodiments of the bridge circuit according to the present invention. A generator 60 of an energy conversion facility, in particular a photovoltaic generator, is attached to the DC voltage attachment terminals DC+ and DC- of the bridge circuit 10. The phase attachment terminals of the bridge circuit 10 are connected to the phase conductors (Phasenleiter) L of the AC voltage network 61. The neutral conductor N of the AC voltage network is also connected to the midpoint M of the bridge circuit 10 via two serial relay contacts of the isolating relay 13.

[0051] The multiphase feeding of alternating current into an AC voltage network can also be easily achieved by means of a bridge circuit, in that each phase of the AC voltage network is assigned a bridge circuit 10 according to the invention and the bridge circuit is attached to the corresponding phase conductor of the AC voltage network by means of its phase connection terminals. Usually, the DC voltage connection terminals DC+, DC- are connected in parallel with one another, but it is also conceivable to connect a separate generator to the corresponding bridge circuit.

[0052] exist Figures 7a to 7kIn FIG. 1 , conceivable switch arrangements of a bridge, which can be used in a bridge circuit according to the invention, are shown in a non-exhaustive enumeration and in a non-prioritized order.

[0053] Figure 7a The switching arrangement in the figure shows two so-called flying capacitor half bridges connected in parallel, in the case of which, via the capacitors arranged in the bridge, in addition to the potential of the DC voltage attachment terminals DC+, DC-, a third potential offset by the capacitor voltage can be provided independently of each other at the bridge output terminals 18a, 18b.

[0054] However, it is also possible to consider Figure 7b As shown in FIG. 1 , two simple half bridges each having two switches are arranged in parallel between the DC voltage terminals DC+, DC− and the bridge outputs 18a, 18b of the two half bridges are each connected to the phase terminal via one of the connection paths. Figure 7a and Figure 7b The switch arrangement in does not require a split intermediate circuit and therefore does not need to be attached to the midpoint of the same intermediate circuit.

[0055] In contrast, Figure 7c to Figure 7k The switch arrangement has an attachment terminal at the midpoint M of the intermediate circuit designed as a split intermediate circuit, so that at least three different potentials can be provided in a clock-controlled manner at the bridge output terminals 18a, 18 and the midpoint M having the potential of the DC voltage attachment terminals DC+, DC-.

[0056] exist Figure 7c , two so-called BSNPC bridges (Bipolar Switched Neutral Point Clamped) connected in parallel to each other are shown, which can also be used and also require a connection to the center point of the split intermediate circuit. If the switches connected to the DC voltage terminals DC+, DC- are replaced by diodes, as in Figure 7d As shown in , the bridge circuit can still be used as a rectifier for powering a DC load.

[0057] exist Figure 7e , two so-called NPC bridges (Neutral Point Clamped Bridges) connected in parallel to one another are shown, which can also be used and likewise require a connection to the center point of the split intermediate circuit.

[0058] exist Figure 7f, two so-called ANPC bridges (Active Neutral Point Clamped-Brücken) connected in parallel to each other are shown, which can also be used and also require a connection to the center point of the split intermediate circuit. In this case, the capacitor 17 is optional and can also be omitted in the case of a modified clock control method.

[0059] exist Figure 7g Another bridge circuit is shown in FIG. 1 , which can also be used and also requires a connection to the center point of the split intermediate circuit. If the switches connected to the DC voltage terminals DC+, DC- are replaced by diodes, as in Figure 7h As shown in , the bridge circuit can still be used as a rectifier for supplying DC loads. Here, the capacitor 17 is also optional and can also be omitted in the case of a suitable clock control method.

[0060] exist Figure 7i , Figure 7j and Figure 7k , three further bridge circuits are shown which can also be used and also require a connection to the center point of the split intermediate circuit. Figure 7a to Figure 7h Unlike the circuit in , five potentials can be provided at the bridge outputs 18a and 18b.

[0061] with Figures 7a to 7k Independently of the switch type shown in FIG. 1 , in principle, at each position, IGBTs, MOSFETs (both preferably as silicon switches or silicon carbide switches), HEMTs or GIT switches (both preferably as gallium nitride switches) can optionally be used for the bridge circuit. Other self-latching switch types can also be considered for use in the bridge.

[0062] Reference numerals list

[0063] 10 Bridge Circuit

[0064] 11 Bridge

[0065] 12a, 12b Filter choke

[0066] 13. Separation relay

[0067] 14, 14a, 14b relay contacts

[0068] 15a, 15b connection path

[0069] 16a, 16b, 16c filter capacitors

[0070] 17 Intermediate circuit capacitor

[0071] 18a, 18b Bridge output

[0072] 32 Filter choke

[0073] 36 Filter capacitor

[0074] 42a, 42b Filter choke

[0075] 46a, 46b Filter capacitor

[0076] 50 Electrical separation plane

[0077] 60 Generator

[0078] 61 AC voltage network

[0079] DC+, DC- DC voltage attachment terminals

[0080] M Midpoint

[0081] AC Phase Attachment Terminal

[0082] L phase conductor

[0083] N Neutral conductor

Claims

1. A bridge circuit (10) for providing an alternating current at phase attachment terminals (AC), the bridge circuit comprising: - a first DC voltage attachment terminal (DC+) and a second DC voltage attachment terminal (DC-), for attaching a DC power source or a DC load, - intermediate circuit (17), a bridge (11) with a bridge switch, which is designed to provide the potential applied to the first DC voltage connection terminal (DC+) and the second DC voltage connection terminal (DC-) independently of one another in a clocked manner at a first bridge output terminal (18a) and a second bridge output terminal (18b), wherein a first connection path (15a) extends between the first bridge output terminal (18a) and the phase attachment terminal (AC), and a second connection path (15b) extends between the second bridge output terminal (18b) and the phase attachment terminal (AC), Each of the connection paths (15a, 15b) has a filter choke (12a, 12b) on the bridge output side, and the filter chokes (12a, 12b) of the connection paths (15a, 15b) are magnetically coupled to each other. It is characterized in that a separation relay (13) having a plurality of relay contacts (14, 14a, 14b) is arranged between the bridge output terminal (18a, 18b) and the phase attachment terminal (AC) in such a way that in the separated sections of the connection paths (15a, 15b), at least one of the relay contacts (14, 14a, 14b) is arranged in each of the connection paths (15a, 15b), respectively.

2. The bridge circuit (10) according to claim 1, wherein: The bridge (11) is designed and configured to provide three potential levels at each of the bridge outputs (18a, 18b) which are formed from the potentials of the direct voltage terminals (DC+, DC-).

3. The bridge circuit (10) according to claim 1, wherein: The bridge (11) is designed and configured to provide five potential levels at each of the bridge outputs (18a, 18b) which are formed from the potentials of the direct voltage terminals (DC+, DC-).

4. The bridge circuit (10) according to any one of the preceding claims, wherein: Two relay contacts (14, 14a, 14b) of the disconnecting relay (13) which can be actuated independently of one another are arranged in series between each of the bridge outputs (18a, 18b) and the phase connection (AC).

5. The bridge circuit (10) according to any one of the preceding claims, wherein: In each of the connecting paths (15a, 15b), two relay contacts (14) of the disconnecting relay (13) are arranged in series in a disconnecting section of the connecting path (15a, 15b).

6. The bridge circuit (10) according to any one of the preceding claims, wherein: The intermediate circuit (17) is a split intermediate circuit having a midpoint (M), and wherein the bridge (11) is established and designed to provide the potential applied to the first DC voltage attachment terminal (DC+), the second DC voltage attachment terminal (DC-) and the midpoint (M) independently of each other in a clocked manner at a first bridge output terminal (18a) and a second bridge output terminal (18b).

7. The bridge circuit (10) according to any one of the preceding claims, wherein: In each of the connection paths (15a, 15b), a filter capacitor (16a, 16b) is respectively attached between the filter choke (12a, 12b) and the separation relay (13), and the filter capacitor is connected to the first DC voltage attachment terminal (DC+), the second DC voltage attachment terminal (DC-) or the midpoint (M) via another attachment terminal.

8. The bridge circuit (10) according to any one of the preceding claims, wherein: In addition, in at least one of the first and second connection paths (15a, 15b), a second filter is arranged between the filter choke (12a, 12b) and the separation relay (13), and the second filter includes a second filter choke (32, 42a, 42b) and a second filter capacitor (36, 46a, 46b).

9. The bridge circuit (10) according to any one of the preceding claims, wherein: A common relay contact (14) of the disconnecting relay (13) is arranged in a common section of the first connecting path (15a) and the second connecting path (15b).

10. The bridge circuit (10) according to claim 9, wherein: A further filter is arranged in a common section of the first connecting path (15a) and the second connecting path (15b), the further filter comprising a further filter choke (32) and a further filter capacitor (36), wherein the common relay contact (14) of the disconnecting relay (13) is arranged between the further filter and the phase connection (AC).

11. An energy conversion installation comprising a bridge circuit (10) according to any one of the preceding claims.

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