Method for operating a full-bridge circuit, voltage converter assembly, and electric drive system

Abstract

The invention relates to a concept for handling a fault in a full-bridge circuit for controlling an electric machine. For this purpose, according to the invention, if both semiconductor switching elements in a half-bridge can no longer be closed, all semiconductor switching elements of the full-bridge circuit that are still functional are closed. In this way, an arc that may occur on a defective semiconductor switching element can be extinguished as quickly as possible.

Description

[0001] Description

[0002] title

[0003] Method for operating a full bridge circuit, voltage converter arrangement and electrical drive system

[0004] Technical field

[0005] The present invention relates to a method for operating a full-bridge circuit, in particular a full-bridge circuit for a voltage converter arrangement. The present invention further relates to a voltage converter arrangement and an electrical drive system with such a voltage converter arrangement.

[0006] background

[0007] Vehicles powered entirely or at least partially by electricity have an electric drive system in which a direct current (DC) from a traction battery is converted into a single- or multi-phase alternating current (AC) by means of a voltage converter (inverter). This AC voltage is then used to drive an electric motor. The voltage converter arrangement typically includes a so-called half-bridge for each phase connection of the electric motor, consisting of two semiconductor switching elements arranged in series or groups of semiconductor switching elements connected in parallel. By selectively opening and closing these semiconductor switching elements, the DC voltage supplied by the traction battery can be converted into a suitable alternating current, which is then used to drive the electric motor according to the specified parameters.During the operation of the electric drive system, individual components can be monitored to detect possible faults and to initiate appropriate countermeasures in case of a fault.

[0008] For example, the publication DE 10 2020 208 973 A1 describes a method and a device for overcurrent detection on circuit breakers in order to initiate a shutdown of the circuit breaker if necessary in the event of a fault.

[0009] Disclosure of the invention

[0010] The present invention provides a method for operating a full bridge circuit, a voltage converter arrangement, and an electrical drive system with the features of the independent claims. Further advantageous embodiments are the subject of the dependent claims.

[0011] Accordingly, the following is planned:

[0012] A method for operating a full-bridge circuit, in particular a full-bridge circuit with multiple half-bridges. Each half-bridge comprises a series connection of two semiconductor switching elements or two groups of semiconductor switching elements connected in parallel. The two series-connected semiconductor switching elements are each connected to each other at a node. The half-bridges are each arranged between two terminals of a DC voltage input of the full-bridge circuit. The individual nodes of the half-bridges are each connected to corresponding terminals of an AC voltage input of the full-bridge circuit. The method includes a step for detecting a malfunction in a semiconductor switching element of a

[0013] Half-bridge. The method further comprises a step for detecting an interruption in a power supply connected to the DC voltage terminal. This interruption can be triggered, in particular, by an overcurrent after the malfunction has occurred in the semiconductor switching element of the half-bridge. The method further comprises a step for closing the two semiconductor switching elements in at least one additional half-bridge. This additional half-bridge is a half-bridge that does not include the semiconductor switching element in which the malfunction was detected. The closing of the two semiconductor switching elements in this at least one additional half-bridge occurs if a malfunction has been detected in the semiconductor switching element.In particular, the two semiconductor switching elements in the at least one additional half-bridge are only closed after it has been determined that the power supply connected to the DC terminal has been interrupted. In other words, the at least one additional half-bridge short-circuits the two terminals of the DC terminal if a malfunction in a semiconductor switching element has been detected and it has also been determined that the power supply connected to the DC terminal has been disconnected.

[0014] Furthermore, the following is planned:

[0015] A voltage converter arrangement comprising a full bridge circuit and a control unit. The full bridge circuit includes several half-bridges. Each half-bridge consists of a series connection of two semiconductor switching elements or two groups of semiconductor switching elements connected in parallel. The two semiconductor switching elements or groups of semiconductor switching elements are connected to each other at a node. The half-bridges are each arranged between two terminals of a DC voltage output. Furthermore, each node of a half-bridge is connected to a corresponding terminal of an AC voltage output. The control unit is designed to detect a malfunction in a semiconductor switching element of a half-bridge. The control unit is also designed to detect an interruption in a power supply connected to the DC voltage output.Furthermore, the control unit is designed to close the two series-connected semiconductor switching elements in at least one additional half-bridge. This additional half-bridge does not include the semiconductor switching element in which a malfunction has been detected. The closing of the two semiconductor switching elements in this additional half-bridge occurs if a malfunction has been detected in the semiconductor switching element, and only after it has been determined that the power supply connected to the DC voltage terminal is interrupted.

[0016] Finally, the following is planned:

[0017] An electric drive system comprising a voltage converter arrangement according to the invention and an electric machine. The electric machine is electrically coupled to the AC voltage terminal of the full-bridge circuit in the voltage converter arrangement. The DC voltage terminal of the full-bridge circuit of the voltage converter arrangement is designed to be electrically coupled to a DC voltage source. In particular, the DC voltage source can be coupled to the DC voltage terminal via a suitable isolating device.

[0018] Advantages of the invention

[0019] To control an electric machine in an electric drive system, a direct current (DC) voltage can be converted into a suitable alternating current (AC) voltage using an electrical converter. The electrical converter typically comprises several semiconductor switching elements that are opened and closed in a controlled manner to generate the desired AC voltage. In very rare cases, there is a risk that a defective semiconductor switching element may prevent it from opening, or may no longer open completely. In the highly improbable event that the second semiconductor switching element in the half-bridge also fails to open due to a defect or other cause, a short circuit occurs between the DC input terminals in this half-bridge.This may result in an arc forming at or above a semiconductor switching element.

[0020] If such a fault occurs during operation of the electric drive system, there is also the risk that even after disconnecting the DC voltage source at the DC terminal, electrical energy can continue to be fed into the converter by an electric machine connected to the AC terminal, which is still rotating during operation. This energy from the electric machine can then continue to power the arc, and the energy in the arc can be converted into thermal energy.

[0021] Based on this understanding, the present invention aims to provide a concept for the described fault condition in which the resulting arc can be extinguished as quickly as possible. To this end, in the event of a fault, the semiconductor switching elements of at least one, preferably several, and in particular all, further half-bridges are closed. This creates parallel current paths through which, on the one hand, the energy supplied by the electric machine can be rapidly dissipated, and, on the other hand, this short-circuit configuration also causes the electrical voltage across the half-bridge with the defective semiconductor switching elements to drop, thus rapidly extinguishing the arc.

[0022] By consciously and actively closing as many as possible

[0023] By removing semiconductor switching elements from the still-functional half-bridges, the duration of the arc over a defective semiconductor switching element can be reduced. This also reduces the electrical energy dissipated by the arc. As a result, in such a fault scenario, it is possible to reduce the transfer of thermal energy from the arc to the surrounding components, thus preventing or at least significantly reducing potential damage or destruction of these components.

[0024] According to one embodiment, detecting a malfunction of a semiconductor switching element in a half-bridge can include detecting a short circuit at the semiconductor switching element. Such a short circuit corresponds to a condition in which the semiconductor switching element is no longer able to completely interrupt an electrical connection between the input and output terminals. In other words, the semiconductor switching element can no longer completely interrupt an electrical connection, even though it is being driven accordingly. Detecting the malfunction can also include, in particular, detecting an arc at the semiconductor switching element. Especially when an arc occurs, a very large amount of thermal energy can be released into the environment. This poses a risk of damaging or even destroying components or parts located near the arc.

[0025] According to one embodiment, the malfunction of the semiconductor switching element in the half-bridge can be detected by means of voltage monitoring at a control terminal of the semiconductor switching element or the complementary semiconductor switching element in the half-bridge. Such voltage monitoring at the control terminals of the semiconductor switching elements can be implemented, for example, by the driver circuits connected to the semiconductor switching elements. However, any other suitable measures for monitoring the semiconductor switching elements and detecting a malfunction in a semiconductor switching element can also be provided. According to one embodiment, the interruption of the power supply connected to the DC voltage terminal is detected using voltage measurement and / or current measurement. In particular, the electrical voltage at the DC voltage terminal or...An electrical current at the DC voltage connection can be monitored. When the power supply is disconnected from the DC voltage connection, the voltage at the DC voltage connection can drop very rapidly, and no further electrical current can flow from the DC voltage source to the DC voltage connection. Therefore, such monitoring allows for the reliable detection of a power supply interruption. Since the necessary sensors may already be available for other purposes, this method of detecting the interruption between the DC voltage source and the DC voltage connection can be implemented very simply and cost-effectively.

[0026] According to a further embodiment, the detection of an interruption in the connection of a power supply connected to the DC voltage terminal can be based on a predetermined time interval between the detection of the malfunction in the semiconductor switching element and the time of detection of the power supply interruption. In other words, the time of detection of the power supply interruption is determined at a point in time that is a predetermined time interval after the time at which the malfunction in the semiconductor switching element was detected. This predetermined time interval can, for example, correspond to the time interval used as the basis for tripping a protective device, in particular an overcurrent protection device or similar.For example, this predetermined time interval could be the period during which an overcurrent protection device responds at its maximum capacity to disconnect the DC voltage source from the DC voltage connection in the event of a fault. This allows the point in time at which it can be assumed that the DC voltage source has been disconnected from the DC voltage connection in the event of a fault to be determined without any additional hardware.

[0027] According to another embodiment, the interruption of the power supply connected to the DC voltage terminal is detected using an external signal. This external signal could, for example, be a signal from an overcurrent protection device. For instance, this signal could be the control signal of a pyrotechnic circuit breaker for the external DC voltage source. Similarly, it is conceivable to provide a trip signal from the pyrotechnic circuit breaker as the signal. However, any other signal related to the interruption of the external power supply is also possible.

[0028] According to one embodiment, closing the two semiconductor switching elements includes closing all semiconductor switching elements in all half-bridges of the full-bridge circuit, in particular closing all semiconductor switching elements in the half-bridges that are parallel to the half-bridge containing the faulty semiconductor switching element. Closing all available semiconductor switching elements creates the greatest possible number of parallel electrical paths suitable for dissipating the electrical energy. This allows an arc at the defective semiconductor switching element to be extinguished as quickly as possible.

[0029] According to one embodiment, the method includes a step for enabling the simultaneous activation of both semiconductor switching elements in a half-bridge if a malfunction of one semiconductor switching element has been detected. By enabling the simultaneous closing of both semiconductor switching elements of a half-bridge in this way, a normally implemented mutual interlock during normal operation can, for example, be overridden. This interlock during normal operation may, for example, be intended to prevent a short circuit between the connection points of the DC voltage terminal caused by a faulty activation of the semiconductor switching elements.If such an interlock is provided, this interlock can be actively and deliberately released after the detection of a malfunction of a semiconductor switching element in order to set a switching state for the rapid extinguishing of an arc, in order to realize the protection concept according to the invention.

[0030] The above embodiments and further developments can be combined with one another as appropriate. Further embodiments, further developments, and implementations of the invention also include combinations of features of the invention described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In particular, those skilled in the art will also add individual aspects as improvements or additions to the respective basic forms of the invention.

[0031] Brief description of the drawings

[0032] Further features and advantages of the invention are explained below with reference to the figures. These show:

[0033] Fig. 1 : a schematic representation of a basic circuit diagram of an electric drive system with a voltage converter arrangement according to one embodiment;

[0034] Fig. 2: a schematic representation of a basic circuit diagram to illustrate the switching states in a full bridge circuit according to one embodiment; and

[0035] Fig. 3: a flowchart as it underlies a method for operating a full bridge circuit according to one embodiment.

[0036] Description of Embodiments Figure 1 shows a schematic representation of a basic circuit diagram of an electric drive system with a voltage converter arrangement 1 according to one embodiment. The voltage converter arrangement 1 comprises a DC voltage terminal 12 with two connection points 12a and 12b. A first connection point 12a can be connected to a corresponding, for example, positive connection point of a DC voltage source 30, for example, an electrical energy storage device such as a traction battery. Similarly, the second connection point 12b can be connected to a corresponding, for example, negative connection point of the DC voltage source 30. A protective device 31, in particular an overcurrent protection device, such as a pyrotechnic circuit breaker, can be provided between the DC voltage source 30 and the DC voltage terminal 12, preferably on or in the DC voltage source 30.This protective device 31 can interrupt the electrical connection between the DC voltage source 30 and the DC voltage terminal 12 of the voltage transformer arrangement 1 when an electric current above a predetermined threshold is detected. Furthermore, other components may also be provided between the DC voltage source 30 and the DC voltage terminal 12 of the voltage transformer arrangement 1, which are not explicitly shown in Figure 1 for the sake of simplicity.

[0037] The voltage converter arrangement 1 further comprises an AC voltage terminal 13 with several AC voltage connection points 13a - 13c. This AC voltage terminal 13 can, for example, be connected to an electric machine 20. In particular, each connection point 13a - 13c of the AC voltage terminal 13 can be connected to a corresponding connection point of the electric machine 20.

[0038] The voltage converter arrangement 1 further comprises a full bridge circuit.

[0039] 10 with several half-bridges 10a - 10c. In particular, a half-bridge 10a - 10c can be provided for each connection point 13a- 13c of the AC voltage connection 13 and thus for each phase connection of the electrical machine 20.

[0040] Each half-bridge 10a - 10c comprises a series connection of two semiconductor switching elements M1a - M1c and M2a - M2c. Instead of a single semiconductor switching element, a group of several semiconductor switching elements connected in parallel can also be provided. In particular, the multiple semiconductor switching elements can be arranged as a group on a common substrate. The term semiconductor switching element will be used hereafter for such an arrangement as well.

[0041] In each half-bridge 10a - 10c, a first semiconductor switching element M1a - M1c is provided between the first terminal 12 of the DC voltage terminal 12 and a node K of the respective half-bridge 10a - 10c, and a second semiconductor switching element M2a - M2c is provided between the node K of the respective half-bridge 10a - 10c and the second terminal 12 of the respective half-bridge 10a - 10c. Each node K of a half-bridge 10a - 10c is connected to a corresponding terminal 13a - 13c of the AC voltage terminal 13.

[0042] The individual semiconductor switching elements M1a-M1c, M2a-M2c of the half-bridges 10a-10c can each be controlled via suitable driver circuits 11a-11c. The individual driver circuits 11a-11c can be controlled by a control device 11 and / or be integrated into such a control device 11.

[0043] In particular, the voltage between the control terminal of a semiconductor switching element, M1a-M1c, M2a-M2c, and a power terminal of the respective semiconductor switching element, M1a-M1c, M2a-M2c, can also be monitored. This allows, for example, the detection of a possible malfunction of a semiconductor switching element M1a-M1c, M2a-M2c. Such a malfunction could, in particular, be an electrically conductive state of a semiconductor switching element M1a-M1c, M2a-M2c, even though the corresponding semiconductor switching element M1a-M1c, M2a-M2c should be open at that time. It is understood, however, that any other suitable measures for monitoring the semiconductor switching elements M1a-M1c, M2a-M2c, and especially for monitoring unwanted electrical conductivity of a semiconductor switching element M1a-M1c, M2a-M2c, are also possible.

[0044] During normal, error-free operation to control the electric machine 20 using electrical energy from the DC voltage source 30, typically only one of the two semiconductor switching elements M1a-M1c, M2a-M2c is closed in each half-bridge. Otherwise, if both semiconductor switching elements of a half-bridge 10a-10c were to close simultaneously, an electrical short circuit could occur between the two connection points 12a-12b.

[0045] In the event of a fault, there is a risk that a semiconductor switching element M1a-M1c, M2a-M2c may no longer be able to completely interrupt the electrical connection between its two power terminals, i.e., between the respective DC voltage terminal 12a or 12b and the node K. If the complementary semiconductor switching element M1a-M1c, M2a-M2c of this half-bridge Oa-10c is then closed, a short circuit occurs between the terminal points 12a, 12b of the DC voltage terminal 12. If such a condition is detected early, the still intact semiconductor switching element M1a-M1c, M2a-M2c should be reopened as quickly as possible. In rare cases, however, it is possible that this complementary semiconductor switching element M1a-M1c, M2a-M2c may also be unable to (completely) interrupt the electrical connection.In this case, a very high electric current will flow from the DC voltage source 30 through the two semiconductor switching elements M1a-M1c, M2a-M2c in the half-bridge 10a-10c with the defective semiconductor switching elements M1a-M1c, M2a-M2c. An arc may form at at least one of the semiconductor switching elements M1a-M1c, M2a-M2c. This arc can release a large amount of thermal energy.

[0046] In such a fault condition, the high electrical current from the DC voltage source 30 will typically trigger an overcurrent protection device 31, thus interrupting the electrical connection between the DC voltage source 30 and the DC voltage terminal 12. This prevents any further electrical energy from flowing from the DC voltage source 30 to the fault location in the half-bridge 11a-11c with the defective semiconductor switching elements M1a-M1c and M2a-M2c.

[0047] However, if the described fault occurs during the operation of the electric machine 20, the electric machine 20 may be in rotation. In this case, the still-rotating electric machine 20 can also feed electrical energy into the full bridge 10 via the AC voltage connection 13, acting as a generator. This electrical energy can then also power the arc at the defective semiconductor switching element M1a-M1c, M2a-M2c.

[0048] The following describes an operating strategy designed to extinguish the arc as quickly as possible in the previously explained fault scenario. The corresponding switching states are shown schematically in Figure 2.

[0049] As can be seen in Figure 2, the arc mentioned above can occur, for example, at the upper semiconductor switching element M1a of the first half-bridge 10a. Furthermore, the complementary semiconductor switching element M2a in this half-bridge 10a can also be permanently conductive. It is understood that the configuration shown here, in the event of a fault in the first half-bridge 10a and an arc at the upper semiconductor switching element M1a, is merely an example and does not represent a limitation of the present invention. Rather, the faults can also occur at other half-bridges, or the arc can occur at a lower semiconductor switching element M2a-M2c.

[0050] As previously explained, the electrical connection between the DC voltage source 30 and the DC voltage terminal 12 is typically interrupted by the activation of a suitable overcurrent protection device 31. The activation of this overcurrent protection device 31 can be signaled to the control unit 11. For example, the overcurrent protection device 31 can directly output a corresponding signal after tripping. Alternatively or additionally, a control signal to trigger this overcurrent protection device 31 can be forwarded to the control unit 11 of the voltage transformer arrangement 1. Furthermore, it is of course also possible to receive any other type of signal for triggering a device to disconnect the electrical connection between the DC voltage source 30 and the DC voltage terminal 12.

[0051] Furthermore, it is also possible for the control unit 11 to detect the fault condition in a half-bridge M1a-M1c, M2a-M2c and then wait a predetermined time period. This predetermined time period can, for example, correspond to the maximum response time of the overcurrent protection device 31. After this time, the control unit 11 can assume that, due to the detected fault, the overcurrent protection device 31 has tripped and interrupted the electrical connection between the DC voltage source 30 and the DC voltage terminal 12. However, any other concept is also fundamentally possible, which allows the control unit 11 to determine a point in time at which, after a fault, the electrical connection between the DC voltage source 30 and the DC voltage terminal 12 has been interrupted.

[0052] After the control unit 11 has detected that a fault has occurred in a half-bridge 10a of the full-bridge circuit 10, in particular a fault as described above with electrical conductivity between both semiconductor switching elements M1a and M2a in a half-bridge 10a, and after the control unit 11 has further detected that the electrical connection between the DC voltage source 30 and the DC voltage terminal 12 has been interrupted, the control unit 11 can close all semiconductor switching elements M1b, M1c, M2b, and M2c in at least one further half-bridge 10b, 10c, but preferably in all further half-bridges 10b, 10c. In this way, the electrical energy supplied by the electric machine 20 can be dissipated as quickly as possible via these short-circuit connections in the further half-bridges 10b, 10c.Furthermore, the electrical voltage across the half-bridge 10a with the defective semiconductor switching elements M1a and M2a can also be reduced. This ensures that any arc that may be burning at a defective semiconductor switching element M1a is extinguished as quickly as possible. This also reduces the thermal energy released into the environment by this arc. Consequently, the risk of damage to or destruction of other components in the vicinity of the defective semiconductor switching element M1a is reduced.

[0053] Figure 3 shows a flowchart of a method for operating a full-bridge circuit 10, in particular a full-bridge circuit 10 for a voltage converter arrangement 1 according to one embodiment. The method can, in principle, comprise any steps suitable for implementing the concept already described above in connection with Figures 1 and 2. Similarly, the voltage converter arrangement 1 described above, or the full-bridge circuit 10 contained therein, can also comprise any components suitable for implementing the method described below.

[0054] The method comprises a step S1 for detecting a malfunction in a semiconductor switching element M1 a-M1 c, M2a-M2c of a half-bridge 10a - 10c of the full-bridge circuit 10. Furthermore, the method comprises a step S2 for detecting an interruption in a power supply 30 connected to the DC voltage terminal 12.

[0055] Finally, the method comprises a step S3 for closing the two semiconductor switching elements M1 a-M1 c, M2a-M2c in at least one further half-bridge 10a - 10c in which no faulty semiconductor switching element M1 a-M1 c, M2a-M2c has been detected. Preferably, in this step S3, all semiconductor switching elements M1 a-M1 c, M2a-M2c of the half-bridges 10a - 10c are closed.

[0056] In summary, the present invention relates to a concept for handling a fault in a full-bridge circuit for controlling an electric machine. For this purpose, it is provided that, in the event that both semiconductor switching elements in a half-bridge can no longer be closed, all still functional semiconductor switching elements of the full-bridge circuit are closed. In this way, any arc that may occur at a defective semiconductor switching element can be extinguished as quickly as possible.

Claims

Claims 1. Method for operating a full-bridge circuit (10) with several half-bridges (10a-10c), wherein each half-bridge (10a-10c) comprises a series connection of two semiconductor switching elements (M1a-M1c, M2a-M2c) which are each connected to each other at a node (K), the half-bridges (10a-10c) are each arranged between two connection points (12a, 12b) of a DC voltage terminal (12), and the nodes (K) of the half-bridges (10a-10c) are each connected to corresponding connection points (13a-13c) of an AC voltage terminal (13), and wherein the method comprises: Detecting (S1) a malfunction in a semiconductor switching element (M1a-M1 c, M2a-M2c) of a half-bridge (10a-10c); Detecting (S2) an interruption of a power supply (30) connected to the DC terminal (12); Closing (S3) of both semiconductor switching elements (M1 a-M1 c, M2a-M2c) in at least one further half-bridge (10a-10c) if a malfunction in a semiconductor switching element (M1a-M1 c, M2a-M2c) has been detected and after it has been determined that the power supply (30) connected to the DC voltage terminal (12) is interrupted.

2. Method according to claim 1, wherein the detection (S1) of the malfunction of the semiconductor switching element (M1a-M1c, M2a-M2c) in a half-bridge (10a-10c) comprises detecting a short circuit, in particular detecting an arc, at the semiconductor switching element (M1a-M1c, M2a-M2c).

3. Method according to claim 1 or 2, wherein the detection (S1) of the malfunction of the semiconductor switching element (M1a-M1c, M2a-M2c) in a half-bridge (10a-10c) is carried out using voltage monitoring at a control terminal of the complementary semiconductor switching element (M1a-M1c, M2a-M2c) in the half-bridge (10a-10c).

4. Method according to one of claims 1 to 3, wherein the detection (S2) of the interruption of the power supply (30) connected to the DC voltage terminal (12) is carried out using a voltage and / or current measurement at the DC voltage terminal (12).

5. Method according to any one of claims 1 to 4, wherein the detection (S2) of the interruption of the power supply (30) connected to the DC voltage terminal (12) is carried out using a predetermined time interval between the detection (S1) of the malfunction and the time of detection of the interruption.

6. Method according to one of claims 1 to 5, wherein the detection (S2) of the interruption of the power supply (30) connected to the DC voltage terminal (12) is carried out using an external signaling, in particular a signaling from an overcurrent protection device (31).

7. Method according to any one of claims 1 to 6, wherein the closing (S3) of the semiconductor switching elements (M1a-M1 c, M2a-M2c) comprises closing both semiconductor switching elements (M1a-M1 c, M2a-M2c) of all half-bridges (10a-10c) in the full-bridge circuit (14).

8. Method according to any one of claims 1 to 7, comprising a step for enabling simultaneous activation of both semiconductor switching elements (M1a-M1c, M2a-M2c) in a half-bridge (10a-10c) if a malfunction of a semiconductor switching element (M1a-M1c, M2a-M2c) has been detected.

9. Voltage converter arrangement (1) comprising: a full bridge circuit (10) comprising several half bridges (10a-10c), each half bridge (10a-10c) comprising a series connection of two semiconductor switching elements (M1a-M1c, M2a-M2c) connected to each other at a node (K), the half bridges (10a-10c) each being arranged between two connection points (12a, 12b) of a DC voltage terminal (12), and the nodes (K) of the half bridges (10a-10c) each being connected to corresponding connection points (13a-13c) of an AC voltage terminal (13), and a control device (11) designed to detect a malfunction in a semiconductor switching element (M1a-M1c, M2a-M2c) of a half bridge (10a-10c), an interruption of a connection at the DC voltage terminal (12) connected power supply (30) to close both semiconductor switching elements (M1a-M1c, M2a-M2c) in at least one further half-bridge (10a-10c),if a malfunction in a semiconductor switching element (M1a-M1c, M2a-M2c) has been detected and after it has been determined that the power supply (30) connected to the DC voltage terminal (12) is interrupted.

10. Electric drive system, comprising: a voltage converter arrangement (1) according to claim 9; and an electric machine (20), wherein the electric machine (20) is electrically coupled to the AC voltage connection (13), and wherein the DC voltage connection (12) of the full bridge circuit (14) is designed to be electrically coupled to a DC voltage source (30).

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