AC / DC converter layout

Abstract

In an AC / DC converter arrangement, it is proposed that: the input of an AC circuit breaker (1) forms the AC input (8) of the arrangement, the output of the AC circuit breaker (1) is connected to the input (9) of a rectifier (21), a smoothing capacitor (4) connects a first output (10) of the rectifier (21) to a second output (11), the first output (10) of the rectifier (21) is connected to a first isolating relay (7), the output of the first isolating relay (7) forms a DC output (12) for connection to a DC network, a control and monitoring unit (15) is designed to initiate, in a first step, the separation of the AC input (8) from the DC output (12, 28) when a short-circuit current is detected, so that a resonant circuit consisting of the smoothing capacitor (4) and the inductance of the DC network connected to the first DC output (12, 28) is excited to oscillate, the first isolating relay (7) then opening.

Description

Technical Field

[0001] The invention relates to an electrical AC / DC converter arrangement. Background Art

[0002] Figure 1 An electrical AC / DC converter arrangement according to the prior art is shown. The AC / DC converter arrangement consists in each case of the following individual components:

[0003] an active rectifier 3 comprising the actual rectifier 21 and a capacitor 4 connected to the output of the rectifier 21, in particular a so-called capacitor bank,

[0004] Input coil 20, also called "boost inductor",

[0005] an electromechanical AC circuit breaker 30 with a typical response time of 5 to 9 ms for short circuit protection on the AC side in long DC lines,

[0006] AC contactor 31, which has a typical response time of 20 to 30 ms to ensure electrical isolation and to switch the rated or operating current,

[0007] a "fast" fuse 32 for protecting the rectifier 3 or the diode in case of a fault between the rectifier 3 and the capacitor bank, since both the AC circuit breaker 30 and the AC contactor 31 would be too slow to ensure protection in this case,

[0008] an electromechanical DC breaker 34 having a typical response time of 5 to 9 ms for short-circuit protection on the DC side,

[0009] • A DC isolating switch 35 with a typical response time of 20 to 30 ms to ensure electrical isolation.

[0010] Furthermore, the installation has an EMC filter 33 and a DC distributor 36 to which different loads can be connected, with a further DC breaker 29 being connected in each case to the respective output of the DC distributor 36. Figure 1 Furthermore, the arrangement according to the state of the art has in each case downstream of the DC breaker 29 a connection which is not in each case Figure 1 The circuit breaker shown in FIG.

[0011] As can be seen from this installation, the protection of such systems or installations is very complex and requires a large number of different individual devices. In particular, special DC circuit breakers and DC power switches are required. Since disconnecting high direct currents is significantly more difficult than disconnecting alternating currents due to the lack of zero crossings of the voltage, the corresponding high-power DC switching devices are in each case technically much more complex than comparable AC switching devices. The DC switching devices are not only more complex in design, but also have a larger volume and, due to the increased complexity, are also more expensive than comparable AC switching devices. Summary of the invention

[0012] It is therefore an object of the present invention to provide an electrical AC / DC converter arrangement of the type mentioned at the outset, by which the aforementioned disadvantages can be avoided and protection of the electrical AC / DC converter arrangement can be ensured simply and with minimal complexity in terms of the number and type of components required.

[0013] This is achieved by the following features according to the invention: an electrical AC / DC converter arrangement comprising at least the following components: an AC breaker, and a rectifier, and at least one smoothing capacitor, and at least one first isolating relay for electrical isolation, and at least one first current sensor, and a control and monitoring unit, the input of the AC breaker forming the AC input of the arrangement, the output of the AC breaker being at least indirectly connected by means of an electrical circuit to the input of the rectifier, the smoothing capacitor connecting a first output of the rectifier to a second output of the rectifier, the first output of the rectifier being further at least indirectly connected by means of an electrical circuit to the input of the first isolating relay, The output of the first isolating relay forms a first DC output of the arrangement and is provided for connecting the DC network to at least one first DC load, the first current sensor is arranged between the smoothing capacitor and the isolating relay, and the AC circuit breaker, the first current sensor and the first isolating relay are connected to the control and monitoring unit by means of a controller, the control and monitoring unit being designed to induce, in a first step, separation of the AC input from the DC output upon detection of a short-circuit current, such that a resonant circuit consisting of the smoothing capacitor and the inductance of the DC network connected to the first DC output is excited to oscillate, the first isolating relay subsequently opening.

[0014] As a result, a safe electrical AC / DC converter arrangement can be provided which has significantly fewer components than is the case with known AC / DC converter arrangements. Furthermore, it is no longer necessary to use special DC switching devices which are able to quench arcs in the case of direct current, since the disconnection occurs on the AC side and a zero crossing is generated by resonance on the DC side, which significantly simplifies the additional disconnection on the DC side.

[0015] In the subject arrangement, even if the first isolating relay is arranged on the DC side, it is possible to design the isolating relay as a conventional AC isolating relay without a DC arc quenching device. On the DC side, special DC switching devices and automatic switches are no longer needed at all.

[0016] Furthermore, fuses can be omitted on the AC side.On the AC side, the electromechanical AC circuit breaker of the AC power switch as well as the fuses are replaced by a single hybrid or semiconductor breaking device.

[0017] In summary, it can therefore be said that the subject measure ensures that the number of switching devices required for the protection of the electrical AC / DC converter arrangement is significantly reduced, in particular without technically complex and complicated DC circuit breakers and DC power switches. In addition, the handling of cumbersome fuses can be omitted. Since such fuses must be replaced and stored accordingly in the event of a fault, the availability of the system can be significantly increased simply by the fact that no fuses are required.

[0018] The invention further relates to a method of disconnecting the subject electrical AC / DC converter arrangement described below:

[0019] A method for disconnecting an AC / DC electrical converter arrangement as described above in the event of a DC short circuit, detecting the short circuit current by means of the first current sensor, switching off the AC circuit breaker in a first step so that a resonant circuit consisting of the smoothing capacitor and the inductance of the DC network connected to the first DC output is excited to oscillate, and subsequently opening the first isolating relay.

[0020] A method for disconnecting an electrical AC / DC converter arrangement as described above in the event of a DC short circuit, detecting the short circuit current by means of the first current sensor, switching off the first semiconductor switch in a first step so that a resonant circuit consisting of the smoothing capacitor and the inductance of the DC network connected to the first DC output is excited to oscillate, and subsequently opening the first isolating relay.

[0021] As a result, the advantages described above for the electrical AC / DC converter arrangement are achieved.

[0022] The following relates to further advantageous embodiments of the invention:

[0023] Preferably, the AC circuit breaker is particularly designed as a hybrid circuit breaker or a semiconductor circuit breaker, and the control and monitoring unit for separating the AC input from the DC output trips the AC circuit breaker.

[0024] Preferably, the AC / DC converter arrangement has a first semiconductor switch arranged between the first output of the rectifier and the smoothing capacitor, and the control and monitoring unit for decoupling the AC input from the DC output disconnects the first semiconductor switch.

[0025] Preferably, the first isolating relay is designed as an automatic AC circuit breaker including a short-circuit release.

[0026] Preferably, the first isolation relay is designed as an AC switch capable of remote tripping, and a trip input of the first isolation relay is connected to the control and monitoring unit.

[0027] Preferably, the control and monitoring unit is designed to determine the time of the zero crossing of the oscillating current after the resonant circuit starts to oscillate, and then output a release pulse to the first isolation relay to disconnect the first isolation relay within a predeterminable time range before and after the determined time of the zero crossing.

[0028] Preferably, at least two components, in particular all components, are arranged as an integrated unit in a common housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The invention will now be described in more detail with reference to the accompanying drawings, in which preferred embodiments are depicted by way of example only. In the drawings:

[0030] Figure 1 is a schematic diagram of an electrical AC / DC converter arrangement according to the prior art;

[0031] Figure 2 a schematic diagram of a first embodiment of the subject electrical AC / DC converter arrangement; and

[0032] Figure 3 Schematic diagram of a second embodiment of the subject electrical AC / DC converter arrangement. DETAILED DESCRIPTION

[0033] Figure 2 and 3 Each shows an electrical AC / DC converter arrangement comprising at least the following components:

[0034] - AC circuit breaker 1, and

[0035] - a rectifier 21, and

[0036] - at least one smoothing capacitor 4, and

[0037] - at least one first isolating relay 7 for electrical isolation, and

[0038] - at least one first current sensor 6, and

[0039] - Control and monitoring unit 15.

[0040] In particular, the subject electrical AC / DC converter is arranged without further disconnecting means on the AC side.

[0041] In particular, the subject AC / DC converter is arranged without special DC disconnecting means or so-called automatic circuit breakers on the DC side. Due to the lack of zero crossings in the case of direct current itself, it is known that quenching the disconnecting arc in the case of direct current is significantly more complicated than in the case of alternating current. Therefore, the direct current or DC disconnecting means are significantly more complicated and also larger than the corresponding AC disconnecting means.

[0042] The subject facility shown in the figure is grounded via a conductor. However, the facility can also be designed to be ungrounded or to have a potential equal to the ground.

[0043] The AC circuit breaker 1 is specifically a so-called hybrid circuit breaker 2 or semiconductor circuit breaker. Semiconductor circuit breakers interrupt current exclusively by means of at least one power semiconductor through which current constantly flows. The hybrid circuit breaker 2 has a parallel circuit consisting of a bypass switch and a power semiconductor circuit, and preferably also an opening contact for electrical isolation.

[0044] Such a disconnecting device is known, for example, from WO 2015 / 028634 A1 of the applicant.

[0045] The AC circuit breaker 1 forms one or more AC inputs 8 of the subject installation. A schematic representation depicting an AC power source 27 is shown, which is shown in each case as a three-phase power source. In particular, the specific number of outer conductors of the AC supply and the presence of a neutral conductor are not necessary and are not limiting. The AC circuit breaker 1 will be designed accordingly, or a plurality of AC circuit breakers 1 may be provided in parallel.

[0046] An output of the AC breaker 1 or outputs of the AC breaker 1 are at least indirectly connected by means of an electrical circuit to one or more inputs 9 of the rectifier 21. In this case, an EMC filter 33 is preferably connected between the AC breaker 1 and the rectifier 21.

[0047] The plant has a rectifier 21. The rectifier 21 or the rectifier switching arrangement 21 is preferably designed so as to comprise a predeterminable number of switchable half-bridges, as is known from inverter technology. The rectifier 21 can also be designed in different ways.

[0048] The arrangement has at least one smoothing capacitor 4, which can of course be formed by any number of discrete capacitors 4 connected to one another. Figure 2 and 3As shown, the smoothing capacitor 4 connects the first output 10 of the rectifier 21 to the second output 11 of the rectifier 21 .

[0049] It is preferably provided that the rectifier 21 and the smoothing capacitor 4 together form part of an “active rectifier 3.” Such an “active rectifier 3” is also referred to as an “active front end.”

[0050] Furthermore, it can be provided that the input coil 20 shown, also referred to as a “boost inductor”, is designed together with an “active rectifier 3 ”. Such an arrangement is referred to as a “boost converter”.

[0051] A first isolating relay 7 is provided to ensure electrical isolation. The first output 10 of the rectifier 21 is connected to the input of the first isolating relay 7 at least by means of an electrical circuit. The rectifier 21 has two outputs of different polarity. It is preferably provided that the first isolating relay 7 has two inputs and two outputs and correspondingly also has two contact disconnection distances, each contact disconnection distance having a contact breaker point, and both outputs 10, 11 of the rectifier 21 are connected to the first isolating relay 7, such as Figure 2 and 3 shown.

[0052] In the subject arrangement, even if the first isolating relay 7 is arranged on the DC side, it is possible to design said isolating relay as a conventional AC isolating relay without a DC arc quenching device.

[0053] It should be noted that according to the first preferred embodiment no further semiconductor switches are arranged in the connection line between the outputs 10, 11 of the rectifier 21 and the first isolating relay 7. The corresponding connection is therefore switchless.

[0054] According to the second preferred embodiment, Figure 3 As shown, provision is made for the arrangement to further have a first semiconductor switch 5 which is connected between the first output 10 of the rectifier 21 and the smoothing capacitor 4 .

[0055] The output 12 or outputs 12, 18 of the first isolating relay 7 forms a first DC output of the arrangement and is provided for connecting the DC network to at least one first DC load 13. No additional DC breakers are required. Figure 2 and 3 Further shown is an electrical fault 26 on the DC side.

[0056] The installation or arrangement has at least one first current sensor 6 arranged between the smoothing capacitor 4 and the isolating relay 7. The first current sensor 6 can also be referred to as a current measuring arrangement. In this case, the first current sensor 6 is used to detect overcurrent and / or short-circuit current, or to record the current curve after separation from the AC side.

[0057] The first current sensor 6 is an AC current sensor and is therefore also able to detect negative polarity currents. Furthermore, the first current sensor is preferably not an effective value sensor but instead measures the instantaneous value of the current.

[0058] For controlling the subject arrangement, provision is made that the arrangement comprises as a further component at least one of the aforementioned control and monitoring units 15. This control and monitoring unit 15 can be designed as a separate unit or integrated in one of the other components.

[0059] Therefore, it is provided that the control and monitoring unit 15 is connected to the AC circuit breaker 1 and the first current sensor 6 at least indirectly by means of the controller, and preferably also to the first isolating relay 7. The control and monitoring unit 15 is preferably further connected to the rectifier 21. If the control and monitoring unit 15 is already integrated in one of these components, it is of course no longer necessary to connect to this one component. Then, in this case, one of the components is the master controller, and the other components are the corresponding controlled devices. The relevant control engineering intelligence can be arranged on different components.

[0060] The control and monitoring unit 15 is designed in particular to include a μC or a μP.

[0061] In the case of individually designed components, the individual components are preferably connected to a control and monitoring unit 15 by means of a bus 14. This bus 14 can be formed by several control lines operating at 24 V and 28 V, respectively. However, any other form of bus 14 can be provided, such as Modbus or USB. However, a radio connection can also be provided.

[0062] As a result, a safe electrical AC / DC converter arrangement can be provided which has significantly fewer components than is the case with known AC / DC converter arrangements. Furthermore, it is no longer necessary to use special DC switching devices which are able to quench arcs in the case of direct current, since the disconnection occurs on the AC side and a zero crossing is generated by resonance on the DC side, which significantly simplifies the additional disconnection on the DC side.

[0063] Furthermore, it is possible to dispense with the fuse 32 on the AC side. On the AC side, the electromechanical AC circuit breaker 30 of the AC power switch 31 as well as the fuse 32 are replaced by a hybrid or semiconductor breaking device 2 .

[0064] In the subject arrangement, even if the first isolating relay 7 is arranged on the DC side, it is possible to design the isolating relay as a conventional AC isolating relay without DC arc quenching means. On the DC side, special DC switching devices and reclosers are no longer needed at all.

[0065] In summary, it can therefore be said that the subject measure ensures that the number of switching devices required for the protection of the electrical AC / DC converter arrangement is significantly reduced, in particular without the need for technically complex and expensive DC circuit breakers and DC power switches. In addition, the handling of cumbersome fuses 32 can be omitted. Since such fuses must be replaced and stored accordingly in the event of a fault, the availability of the system can be significantly increased simply by the fact that fuses 32 are not required. Therefore, the subject arrangement is designed to be fuse-free.

[0066] The subject installation or arrangement is intended to protect a downstream or connected DC network. As explained below, this DC network to be protected is itself related to the operating mode of the device.

[0067] Provision is made for the control and monitoring unit 15 to initiate a separation of the AC input 8 from the DC output 12 , 28 in a first step when the current sensor 6 detects a predeterminable short-circuit current on the DC side.

[0068] In accordance with Figure 2 In a first preferred embodiment, the AC input 8 is separated from the DC outputs 12, 28 by a control and monitoring unit 15, which trips or actuates the AC circuit breaker 1 accordingly.

[0069] As a result, a simple design with particularly low resistance on the DC side can be achieved. This immediately stops the flow of current.

[0070] It has proven to be particularly advantageous if the AC circuit breaker 1 is designed as a hybrid circuit breaker 2 or as a semiconductor circuit breaker.

[0071] In any case, this ensures that the separation process occurs quickly so that the voltage at the smoothing capacitor 4 is not zero when separation of the AC input has ended. This is important for generating oscillations on the DC side, as will be explained in more detail in several paragraphs.

[0072] As another component, according to Figure 3 The second preferred embodiment of the invention has a first semiconductor switch 5 which is arranged between the first output 10 of the rectifier 21 and the smoothing capacitor 4. The AC side can be quickly separated from the DC side by means of the first semiconductor switch 5, independently of a corresponding design of the AC circuit breaker 1.

[0073] In any case, it is ensured that this separation occurs quickly so that the oscillation occurs on the DC side. As a result, the expected operating mode can be ensured even if the AC circuit breaker 1 is designed as a "slower" AC circuit breaker 1. In this embodiment, of course, the AC circuit breaker 1 can also be designed as a hybrid circuit breaker 2 or a semiconductor circuit breaker. The subject arrangement of the first semiconductor switch 5 is substantially more efficient compared to the arrangement of the SSCB on the DC side. In addition, the subject arrangement of the rectifier 21 and the first semiconductor switch 5 makes bidirectional current flow possible.

[0074] The first semiconductor switch 5 is preferably designed as an IGBT or a MOSFET. When the semiconductor switch 5 is designed as an IGBT, a so-called anti-parallel diode is also provided, such as Figure 3 It is also possible to arrange a plurality of first semiconductor switches 5 connected in parallel at this position.

[0075] In accordance with Figure 3 In the second preferred embodiment, the AC input 8 is separated from the DC output 12 , 28 by the control and monitoring unit 15 , which disconnects the first semiconductor switch 5 to separate the AC input 8 from the DC output 12 , 28 .

[0076] It is preferably provided that the AC circuit breaker 1 is also switched off, but this is not essential.

[0077] According to a preferred refinement, it is further provided in both embodiments that the active switching elements of the rectifier 21 are also disconnected additionally or substantially simultaneously with the separation of the AC input 8 from the DC output 12, 28. In this case, it is particularly provided that upon detection of a predeterminable overcurrent or short-circuit current on the DC side, the active switching elements of the rectifier 21 are first disconnected and the AC breaker 1 or the first semiconductor switch 5 is subsequently or substantially simultaneously switched off.

[0078] As an alternative to detecting the overcurrent by means of the first current sensor 6, the overcurrent can also be detected by the drive circuit of the rectifier 21. Furthermore, when appropriately designed by means of PWM, the rectifier 21 can also limit the overcurrent.

[0079] By disconnecting the AC input 8 from the DC output 12, 28, a resonant circuit consisting of the capacitance of the smoothing capacitor 4 and the inductance of the DC network connected to the first DC output 12, 28 is excited to oscillate. In this case or as a result of this, an alternating current attenuation occurs within the DC network. For this purpose, a separation of the AC input must be performed as long as the voltage at the smoothing capacitor 4 is not zero. This is always guaranteed by the capacitance value of a typical smoothing capacitor 4 and the response time of modern electronics itself. In addition, the smoothing capacitor 4 may not be a capacitor with a predetermined polarity, i.e., for example, an electrolytic capacitor.

[0080] Due to the lines that must be present, the typical inductance value of the connected DC network is between 10 μH and 200 μH, which can also be called leakage inductance. When disconnected from the AC side, this generates a current oscillating at a frequency between 100 Hz and 1000 Hz.

[0081] Of course, other oscillation frequencies may occur here. This is an oscillation that has been excited and whose amplitude is reduced due to the capacitor charge reduction and damping.

[0082] The oscillations thus generated have zero crossings and simplify disconnection on the DC side, which is necessary to achieve galvanic isolation, which is why the first isolating relay 7 is opened after separation of the AC input 8 from the DC output 12 , 28 .

[0083] Depending on the design of the first isolating relay 7 , the first isolating relay 7 opens or disconnects in different ways or may open or disconnect in different ways.

[0084] According to a first preferred embodiment of the first isolating relay 7, it is provided that the first isolating relay 7 is designed as an automatic AC circuit breaker including a short-circuit release, which is preferably electromechanical. Such an automatic AC circuit breaker with a short-circuit release is, for example, a so-called MCB. However, the relevant automatic AC circuit breaker can also be designed as a hybrid switching device. It has been shown that the short-circuit release of such an automatic AC circuit breaker is tripped by the resonant circuit current generated when the connection is released, and such an automatic AC circuit breaker is disconnected even without additional actuation.

[0085] According to a second preferred embodiment of the first isolating relay 7, it is provided that the first isolating relay 7 is designed as a remotely trippable AC switch, the trip input of which is connected to the control and monitoring unit 15. In this case, it can also be provided that the first isolating relay 7 in the form of an automatic AC circuit breaker is also designed to be remotely trippable and has a trip input.

[0086] The control and monitoring unit 15 is preferably designed to determine the time of the zero crossing of the oscillating current after the resonant circuit starts to oscillate, and then output a disconnection pulse to the first isolation relay 7 to disconnect the first isolation relay 7 in a predeterminable time range before and after the determined time of the zero crossing.

[0087] As a result, the switching contacts of the first isolating relay 7 can be disconnected when the load on the switching contacts is very low. The bandwidth of a switch or relay suitable for use as the first isolating relay 7 can thereby be significantly increased. Even though the AC-MCB is capable of interrupting high alternating currents and quenching the resulting AC switching arc at any time, this is not the case for conventional relays intended to switch operating currents. By intentionally disconnecting at specific times when a small current is expected, in particular at the shortest possible time before the zero crossing, it is also possible to use relays that are themselves designed only for switching during operation.

[0088] The time of the zero crossing of the oscillating current can be determined in various ways. According to one embodiment, it is further provided that the subject installation is trained during its installation based on a plurality of test faults or test versions. As a result, the control and monitoring unit 15 already "knows" the expected magnitude of the oscillation frequency when switched off. In the event of a disconnection during subsequent operation, the gradient of the current rise is then determined. The gradient and the previous training can then be used to determine quite easily and with little computational effort the frequency or period of the relevant oscillation or the expected time of the first zero crossing quite accurately.

[0089] In this case, when determining the time of the first zero crossing, in particular another actual current curve to be measured is taken into account, in particular up to the first inflection point, and for this current curve, in particular the time of the first inflection point is taken into account. In addition, the data determined here are also used to adjust the settings stored in the control and monitoring unit 15 after training.

[0090] The subject arrangement can be designed completely with individual components. However, it can also be provided that at least two components, in particular all components, are arranged as an integrated unit in a common housing.

[0091] As a result, a compact design is achieved and wiring errors can be avoided.

[0092] Therefore, if a DC short circuit occurs, the subject arrangement performs the following method: the short circuit current is detected by the first current sensor 6, the AC circuit breaker 1 is switched off in a first step so that the resonant circuit consisting of the smoothing capacitor 4 and the inductance of the DC network connected to the first DC output 12, 28 is excited to oscillate, and then the first isolation relay 7 is disconnected.

[0093] If the first semiconductor switch 5 is arranged at the described position in the relevant facility, it is provided that: in the method, a short-circuit current is detected by the first current sensor 6, and in a first step, the first semiconductor switch 5 and the AC circuit breaker 1 are switched off, so that a resonant circuit consisting of the smoothing capacitor 4 and the inductance of the DC network connected to the first DC output 12, 28 is excited to oscillate, and then the first isolating relay 7 is disconnected.

Claims

1. An AC / DC converter device comprising at least the following components -AC circuit breaker (1), and - a rectifier (21), and - at least one smoothing capacitor (4), and - at least one first isolating relay (7) for electrical isolation, and - at least one first current sensor (6), and - control and monitoring unit (15), The input of the AC circuit breaker (1) forms the AC input (8) of the device, the output of the AC circuit breaker (1) is at least indirectly connected by means of an electrical circuit to the input (9) of the rectifier (21), the smoothing capacitor (4) connects the first output (10) of the rectifier (21) to the second output (11) of the rectifier (21), the first output (10) of the rectifier (21) is further at least indirectly connected by means of an electrical circuit to the input of the first isolating relay (7), the output of the first isolating relay (7) forms the first DC output (12) of the device and is provided for connecting the DC network to at least one first DC load (13), The first current sensor (6) is arranged between the smoothing capacitor (4) and the first isolating relay (7), and the AC circuit breaker (1), the first current sensor (6) and the first isolating relay (7) are connected to the control and monitoring unit (15) by means of a controller, the control and monitoring unit (15) being designed to initiate, in a first step, the separation of the AC input (8) from the DC output (12, 28) when a short-circuit current is detected, so that a resonant circuit consisting of the smoothing capacitor (4) and the inductance of the DC network connected to the first DC output (12, 28) is excited to oscillate, the first isolating relay (7) then opening.

2. The AC / DC converter device according to claim 1, characterized in that: The AC circuit breaker (1) is designed as a hybrid circuit breaker (2) or a semiconductor circuit breaker, and the control and monitoring unit (15) for separating the AC input (8) from the DC output (12, 28) trips the AC circuit breaker (1).

3. The AC / DC converter device according to claim 1 or claim 2, characterized in that: The AC / DC electrical converter device has a first semiconductor switch (5) arranged between the first output (10) of the rectifier (21) and the smoothing capacitor (4), and the control and monitoring unit (15) for separating the AC input (8) from the DC output (12, 28) disconnects the first semiconductor switch (5).

4. The AC / DC converter device according to claim 1, characterized in that: The first isolating relay (7) is designed as an automatic AC circuit breaker including a short-circuit release.

5. The AC / DC converter device according to claim 1, characterized in that: The first isolation relay (7) is designed as an AC switch capable of remote tripping, and a trip input of the first isolation relay (7) is connected to the control and monitoring unit (15).

6. The AC / DC converter device according to claim 1, characterized in that: The control and monitoring unit (15) is designed to determine the time of the zero crossing of the oscillating current after the resonant circuit starts to oscillate, and then output a disconnecting pulse to the first isolating relay (7) to disconnect the first isolating relay (7) within a predeterminable time range before and after the determined time of the zero crossing.

7. The AC / DC converter device according to claim 1, characterized in that: At least two components are arranged as an integrated unit in a common housing.

8. The AC / DC converter device according to claim 1, characterized in that: All components are arranged as an integrated unit in a common housing.

9. The AC / DC converter device according to claim 4, characterized in that: The automatic AC circuit breaker is electromechanical.

10. A method for disconnecting an AC / DC electrical converter device according to claim 1 in the event of a DC short circuit, detecting a short circuit current by means of the first current sensor (6), switching off the AC circuit breaker (1) in a first step so that a resonant circuit consisting of the smoothing capacitor (4) and the inductance of the DC network connected to the first DC output (12, 28) is excited to oscillate, and subsequently opening the first isolating relay (7).

11. A method for disconnecting an AC / DC electrical converter device according to claim 3 in the event of a DC short circuit, detecting a short circuit current by means of the first current sensor (6), switching off the first semiconductor switch (5) in a first step so that a resonant circuit consisting of the smoothing capacitor (4) and the inductance of the DC network connected to the first DC output (12, 28) is excited to oscillate, and subsequently disconnecting the first isolating relay (7).

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