Voltage monitoring device for a cell stack, particularly a fuel cell stack

Abstract

A voltage monitoring device (1) for a battery stack (2) including a plurality of electrical plates (4) sandwiching an insulating layer (6) is described, the voltage monitoring device (1) being configured to monitor the voltage of at least one electrical plate (4) of the battery stack (2), the voltage monitoring device (1) including at least one voltage monitoring unit (8) having a contact element (10) in contact with the at least one electrical plate (4), the voltage monitoring device (1) including a first signal line (14) configured to provide a first signal from a signal source to a processing unit (16), the voltage monitoring unit (8) including a first signal path interruption element (12) disposed on the first signal line (14), the first signal path interruption element (12) connected to the contact element (10) and configured to transfer the first signal depending on the voltage present on the at least one electrical plate (4).

Description

[Technical Field]

[0001] The invention relates to a voltage monitoring device for a cell stack, in particular a fuel cell stack, according to claim 1. [Background technology]

[0002] Typically, a cell stack is composed of multiple stacked electrical plates separated from each other by insulating layers. In the case of a fuel cell stack, the electrical plates are bipolar plates, and the insulating layers are multilayer membrane electrode assemblies. The bipolar plates themselves are a combination of anode and cathode plates fixed together, with adjacent bipolar plates separated, or sandwiched, by a membrane electrode assembly. The cathode and anode plates that form the bipolar plates are typically conductive metal or graphite plates, so-called flow field plates, with a reactant flow field on one side and a cooling fluid flow field on the other. In the assembled membrane electrode assembly, the flow field plates are positioned on top of each other, with the cooling fluid flow fields facing each other and the reactant flow fields facing the sandwiching membrane electrode assembly. Electric current generated by the membrane electrode assembly during fuel cell stack operation results in a potential difference between the bipolar plate assemblies.

[0003] During operation of a battery stack, the voltages generated by the stacked cells must be monitored to ensure that the stack is operating within intended operating parameters. To this end, each electrical plate typically includes a voltage monitoring unit that is affixed to the electrical plate and has wires connecting the voltage monitoring unit to an external voltage monitoring controller that monitors and controls the operation of the stack.

[0004] The voltage of a cell stack can be monitored by measuring the voltage of each electrical plate and comparing each measured voltage to a reference or threshold voltage. Alternatively, the voltage in a fuel cell stack can be measured by measuring the voltage of one plate relative to the voltage of the previous plate and monitoring the difference. In either case, measurement of the voltage of each plate is required, which requires corresponding measurement means that are costly. Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a voltage monitoring device that is cost effective and easy to implement in a cell stack, particularly a fuel cell stack. [Means for solving the problem]

[0006] This object is solved by a voltage monitoring device for a battery stack according to claim 1.

[0007] The voltage monitor is configured to monitor the voltage of at least one electrical plate of a cell stack, which may be, in particular, a fuel cell stack, and which may include multiple electrical plates sandwiching an insulating layer.

[0008] It should be noted that in general, the term "electrical plate" in this application does not necessarily refer to a rigid electrical plate, and a flexible layered electrical element (anode or cathode) may also be referred to as an electrical plate in this application.

[0009] Additionally, the cell stack may be a fuel cell stack, in which case the electrical plates are bipolar plates consisting of anode and cathode plates fixed together, and in which case the insulating layers are multilayer membrane electrode assemblies. The bipolar plates are typically rigid metal or graphite plates equipped with flow field structures for supplying and distributing reactants and / or coolant to the bipolar plates and / or adjacent membrane electrode assemblies.

[0010] The voltage monitoring device includes at least one voltage monitoring unit with a contact element. The contact element may be connected to at least one of the plurality of electrical plates, for example in the form of a pin or other type of connector, or may be welded directly to at least one of the electrical plates. In a preferred embodiment described below, there are one or more voltage monitoring units, each with a contact element, and each of the contact elements is connected to one of the plurality of electrical plates.

[0011] To monitor the voltage of the battery stack, the voltage monitoring device includes a first signal line configured to provide a first signal from a signal source to the processing unit, and the voltage monitoring unit includes a first signal path interruption element disposed on the first signal line, the first signal path interruption element connected to the contact element and configured to transfer the first signal depending on the voltage present on the electrical plate.

[0012] Therefore, instead of directly measuring and monitoring the voltage of the electrical plate, the voltage monitoring device proposed herein uses an indirect monitoring method. A first signal is transmitted to a processing unit on a first signal line. The first signal itself is applied to the first signal line independently of the voltage of the electrical plate. For example, the first signal on the first signal line may originate from a light source or a power source, such as a current source or a voltage source.

[0013] Alternatively, the signal source may be a first electrical plate of the plurality of electrical plates, meaning that the first signal will originate from the first electrical plate and be provided to the first signal line, which will then function as the first signal on the signal line, after which transmission on the first signal line may be interrupted, or the first signal may be forwarded using a further voltage monitoring unit and a corresponding signal path interruption element, as described below.

[0014] However, transmission of the first signal on the first signal line depends on the voltage of the electrical plates, as described below. The voltage of at least one electrical plate is tapped by a contact element and transmitted to a first signal path blocking element. The first signal path blocking element then closes (i.e., connects) or opens (i.e., blocks) the first signal line depending on the tapped voltage of the at least one electrical plate. Alternatively, the first signal path blocking element may open to transmit a signal on the first signal line or close to block the first signal line depending on the tapped voltage of the at least one electrical plate. When the first signal path blocking element closes the first signal line, the first signal is transferred to the processing unit. When the first signal path blocking element opens (i.e., blocks) the first signal line, the first signal is not transferred to the processing unit.

[0015] The processing unit can then monitor only whether the first signal is received. If the processing unit does not receive any signal, it may interpret this as meaning that at least one electrical plate has no voltage or that the voltage is too low, and that the electrical plate is not operating as intended, i.e., not operating within the intended operating parameters. Alternatively, depending on the implementation of the signal path blocking element as described above, the processing unit may receive a signal, but at least one electrical plate may have no voltage or that the voltage is too low, and that this may be interpreted as meaning that the electrical plate is not operating as intended. For example, this may be particularly true if the electrical plate is defective. Thus, the proposed voltage monitoring device provides a simple and cost-effective way to monitor electrical plate voltage without actually measuring the electrical plate voltage.

[0016] Alternatively, depending on the implementation of the signal path blocking element as described above, if the processing unit receives a signal, it may interpret this as an electrical plate not operating as intended because there may be no voltage or the voltage may be too low on at least one electrical plate. Thus, the combination of the signal path blocking element and the signal line may forward a signal on a first signal line if the electrical plate is operating as intended, and not forward the signal (i.e., block the signal line) if the electrical plate is not operating as intended. Alternatively, conversely, the combination of the signal path blocking element and the signal line may not forward a signal on a first signal line (i.e., interrupt the signal line) if the electrical plate is operating as intended, and forward the signal if the electrical plate is not operating as intended. Thus, in the first exemplary implementation, the processing unit may determine that the electrical plate is not operating as intended if it does not receive a signal, and in the second exemplary implementation, the processing unit may determine that the electrical plate is not operating as intended if it receives a signal. It should be noted below that both implementations may be equally used, and that even if only one possible implementation is described, the same features and examples apply to the other implementation.

[0017] According to one embodiment, the first signal path blocking element is configured to forward or block the first signal when a voltage present on the at least one electrical plate exceeds a reference threshold voltage. Conversely, the first signal path blocking element may be configured to block signal transmission on the first signal line or forward the signal when a voltage present on the at least one electrical plate is below the reference threshold voltage. The reference threshold voltage would be a voltage considered to distinguish a normal operating voltage or voltage range of the at least one electrical plate from a voltage indicative of a defect in the at least one electrical plate.

[0018] According to a further embodiment, the first signal is an electrical signal, and the first signal path interruption element is a relay, an electrical switch, or an electromechanical switch. The electrical signal may be a voltage or current signal that can be received by the processing unit. The first signal path interruption element may be any type of switch-like element that can interrupt signal transmission of the first signal on the first signal line or forward the first signal. For example, the signal path interruption element may be a relay in the form of a transistor, particularly a bipolar transistor. The relay can be activated or switched by voltages present on its electrical plates. For example, if the relay is a transistor, the voltages on the electrical plates are applied to the base of the transistor, and the transistor is connected, particularly when the voltage on at least one electrical plate exceeds a reference threshold. The first signal is then transmitted to the first signal line via the transistor and forwarded to the processing unit.

[0019] According to an alternative embodiment, the first signal may be an optical signal, and the signal path blocking element may be an electrical switch or an electromechanical switch (e.g., a piezoelectric element). In this case, the first signal line may be an optical fiber or the like transmitting an optical signal, and the signal path blocking element may be configured to block propagation of the optical signal on the first signal line. For example, when a piezoelectric element, which is an electromechanical switch actuated by voltage, is used, the piezoelectric element may be affected by the presence or absence (depending on the actual implementation) of voltage, thereby opening or closing the optical path.

[0020] According to a further embodiment, the voltage monitoring unit further includes a voltage fluctuation equalization element disposed between the contact element and the first signal path blocking element and configured to transmit a voltage from the contact element to the first signal path blocking element when the voltage exceeds an equalization threshold voltage. Such a voltage fluctuation equalization element can be implemented, for example, using a resistor or any type of filtering element capable of equalizing voltage fluctuations. The voltage fluctuation equalization element can be used to eliminate voltage fluctuations, i.e., to equalize voltage fluctuations. Such fluctuations can cause the first signal path blocking element to switch between two different stages very frequently, e.g., even in the absence of degradation of at least one electrical plate, typical fluctuations can cause the voltage to change within a small range without significant change. Using such a voltage fluctuation equalization element can prevent the first signal path blocking element from switching between two stages without degradation of at least one electrical plate. Because unnecessary switching of the first signal path blocking element is reduced by the voltage fluctuation equalizing element, the first signal path blocking element may be protected because voltage fluctuations are filtered and do not affect signal path blocking elements downstream of the voltage fluctuation equalizing element. Reducing switching of the signal path blocking element may extend the life of the signal path blocking element.

[0021] According to a further embodiment, the voltage monitoring unit, i.e., the combination of the voltage fluctuation leveling element and the signal path blocking element, can be used to define a reference threshold voltage below which the electrical plates are considered not to be operating as intended, i.e., when at least one electrical plate generates a voltage below such reference threshold voltage, the signal path blocking element blocks signal transmission on the signal line or allows signals on the signal line to be forwarded.

[0022] According to a further embodiment, the processing unit is configured to output a warning signal if the first signal is not transferred to the processing unit. As already mentioned above, the processing unit will determine that at least one of the electric plates is not operating as intended if the processing unit does not receive the first signal. In this case, the processing unit can output a warning signal indicating that at least one electric plate is not operating as intended. Alternatively, as mentioned above, the processing unit can output a warning signal when it receives the first signal.

[0023] According to a further embodiment, the voltage monitoring device includes a plurality of voltage monitoring units, each including a contact element in contact with one of the plurality of electrical plates. Each voltage monitoring unit further includes a first signal path blocking element disposed on the first signal line, connected to the contact element and configured to forward a first signal depending on the voltage present at the respective electrical plate. The first signal path blocking elements of all voltage monitoring units are connected in series. Therefore, if one of the electrical plates is not operating as intended, the voltage generated by the non-operating electrical plate will be below the aforementioned reference threshold voltage, causing the corresponding first signal path blocking element to block the first signal line, and the first signal will not be received by the processing unit. Conversely, if the voltage generated by the respective electrical plate exceeds the reference threshold voltage, the first signal path blocking element will pass the first signal. In this case, the processing unit will receive the first signal. As described above, the blocking and forwarding of signal transmission can be reversed, i.e., the signal will be forwarded if the electrical plate is not operating as intended, and the signal will not be forwarded if the electrical plate is operating as intended.

[0024] Therefore, instead of monitoring the exact voltage of each electrical plate, it is sufficient to monitor the voltage of the electrical plates in a more abstract manner. Because if one of the electrical plates is not operating as intended, the completed battery stack must be disassembled, it is sufficient to monitor the voltage of all electrical plates as a whole. If one of the electrical plates is not operating as intended, the first signal is not transmitted to the processing unit (or the first signal is transmitted as described above), and the processing unit determines that at least one electrical plate is not operating as intended, i.e., that the entire stack is not operating as intended, although it does not know which electrical plate is not operating as intended. In this case, after the entire battery stack is disassembled, each electrical plate can be checked for its functionality. In this way, the voltage monitoring device described herein provides a simple and cost-effective method for monitoring a battery stack. Alternatively, an additional evaluation unit can be installed to individually evaluate each electrical plate before disassembling the entire battery stack. For example, such an evaluation unit can be attached to each electrical plate for further testing.

[0025] According to another embodiment, only some of the voltage monitoring units include a signal path interruption element. According to this embodiment, some of the voltage monitoring units include only a contact element for tapping the voltage of a corresponding electrical plate. The tapped voltages of multiple consecutive electrical plates are transmitted to a respective voltage monitoring unit including a signal path interruption element. The voltage monitoring unit switches the signal path interruption element based on the cumulative total voltage of the previous electrical plate. Thus, instead of interrupting the first signal line when the voltage of the corresponding electrical plate falls below a defined threshold, the voltage monitoring unit interrupts the first signal line when the cumulative total voltage of the previous electrical plate falls below a predefined threshold. Alternatively, the voltage monitoring unit can forward a signal on the first signal line when the cumulative total voltage of the previous electrical plate falls below a predefined threshold.

[0026] For example, each fifth voltage monitoring unit includes a signal path blocking element. The first through fourth voltage monitoring units sample the voltages of their corresponding electrical plates and forward the sampled voltages to the fifth voltage monitoring unit. The fifth voltage monitoring unit switches the signal path blocking element when the cumulative voltages of the first through fourth and fifth electrical plates are below or above a predefined threshold, as described above.

[0027] According to a further embodiment, the voltage monitoring device includes a second signal line connected in parallel with the first signal line. In this embodiment, the voltage monitoring unit includes a second signal path blocking element disposed on the second signal line and connected in parallel with the first signal path blocking element. The first and second signal path blocking elements can accommodate different threshold voltages, thereby realizing more detailed monitoring of the electrical plate.

[0028] For example, the first signal path blocking element may be configured to transmit (or block) a first signal when the voltage of the electrical plate exceeds a first reference voltage, and the second signal path blocking element may be configured to transmit (or block) a second signal when the voltage of the electrical plate exceeds a second reference voltage. Preferably, the first and second reference voltages are different from each other. This advantageously allows for different warning stages to be implemented. For example, the first signal path blocking element functions as a first warning stage, where the first signal path blocking element blocks transmission of the first signal when the voltage generated by the electrical plate falls below a higher reference threshold voltage. This higher reference threshold voltage indicates that the battery stack is still functional but is approaching a critical state. If the generated voltage further falls below the lower reference threshold voltage of the second signal path blocking element, the processing unit can determine that the battery stack needs to be disassembled and at least one of the electrical plates needs to be replaced.

[0029] The voltage monitoring device may be expandable as needed, for example, by adding a third signal line and a third signal path blocking element, a fourth signal line and a fourth signal path blocking element, etc. The more signal lines and corresponding signal path blocking elements used, the more different warning levels can be implemented.

[0030] It should be noted that in this embodiment, when multiple voltage monitoring units are used, the first signal path blocking elements of all voltage monitoring units are connected in series, the second signal path blocking elements of all voltage monitoring units are also connected in series, and so on.

[0031] Further preferred embodiments are defined in the description and drawings as well as in the dependent claims, in which respect an element described or shown in combination with other elements may also be present alone or in combination with other elements without departing from the scope of protection.

[0032] Preferred embodiments of the invention will now be described with reference to the drawings, which are for illustrative purposes only and are not intended to limit the scope of protection, which is defined solely by the appended claims. [Brief explanation of the drawings]

[0033] [Figure 1] 1 shows a first embodiment of a voltage monitoring device for a battery stack. [Figure 2] 2 shows a second embodiment of a voltage monitoring device for a battery stack. [Figure 3] 10 shows a third embodiment of a voltage monitoring device for a battery stack. DETAILED DESCRIPTION OF THE INVENTION

[0034] In the following, identical or similarly functioning elements are designated with the same reference numerals.

[0035] 1 shows a voltage monitoring device 1 for a cell stack 2, for example a fuel cell stack. The cell stack 2 includes a number of electrical plates 4-1 to 4-5 sandwiching insulating layers 6-1 to 6-4.

[0036] The battery stack 2 generates a total voltage as a result of the individual voltages of each electrical plate 4-1 to 4-5. Because the electrical plates 4-1 to 4-5 may wear over time and the total voltage generated is dependent on each electrical plate 4-1 to 4-5, the voltage generated must be monitored.

[0037] For this purpose, the voltage monitoring device 1 includes a plurality of voltage monitoring units 8-1 to 8-5, preferably one for each of the electrical plates 4-1 to 4-5. Each voltage monitoring unit 8-1 to 8-5 includes a contact element 10-1 to 10-5. Each contact element 10-1 to 10-5 may be connected to one of the electrical plates 4-1 to 4-5, for example, in the form of a pin or other type of connector, or may be welded directly to the electrical plate. Alternatively, the contact elements 10-1 to 10-2 may be disposed on the respective electrical plate 4-1 to 4-5, for example, by molding, preferably by injection molding.

[0038] Via contact elements 10-1 to 10-5, the voltages of the electric plates 4-1 to 4-5 are respectively taken out and transmitted to first signal path blocking elements 12-1 to 12-5. The first signal path blocking elements 12-1 to 12-5 are arranged on a first signal line 14 configured to transmit a first signal to a processing unit 16.

[0039] In the following, the signal is an electrical signal, and the signal path blocking element is an electrical switch, e.g., a transistor. However, it should be noted that the signal may also be an optical signal, and the signal path blocking element may be an electromechanical switch, such as a piezoelectric element. The following description also applies to such embodiments. Furthermore, in the following, the signal path blocking element is configured to block signal transmission when one electrical plate is not operating as intended. However, the following description is equally applicable to embodiments in which the signal path blocking element is configured to forward a signal when the electrical plates are not operating as intended and to block signal transmission when the electrical plates are operating properly.

[0040] The signal may originate from a power source, such as a voltage source. Alternatively, the voltage on the first electrical plate 4-1 may be used as the signal transmitted on the signal line 14. The first signal line 14 provides the first signal to the processing unit 16. Based on the received signal, the processing unit 16 can determine whether the cell stack 2 is operating properly, as described in more detail below.

[0041] The first signal path blocking elements 12-1 to 12-5 receive the voltages of the electrical plates 4-1 to 4-5 via the contact elements 10-1 to 10-5. Depending on the respective voltages, each of the first signal path blocking elements 12-1 to 12-5 forwards or blocks transmission of a signal on the first signal line 14. If all generated voltages are sufficient, each of the first signal path blocking elements 12-1 to 12-4 forwards the signal to the next first signal path blocking element 12-2 to 12-5, respectively, until the last first signal path blocking element 12-5 forwards the signal to the processing unit 16.

[0042] The signal path interruption elements 12-1 to 12-5 can be realized, for example, using electrical switches that open when the voltage falls below a threshold and close when the voltage exceeds the threshold. In the former case, the signal line 14 is interrupted, and in the latter case, the signal line 14 is closed, and the signal is transferred to the next signal path interruption element 12-2 to 12-5. For example, the signal path interruption elements 12-1 to 12-5 can be transistors. When the voltage of the contact elements 10-1 to 10-5 is applied to the base of the transistor, and the applied voltage exceeds a threshold, a voltage flows from the emitter to the collector or vice versa, depending on the type of transistor.

[0043] For example, if the voltage of electrical plate 4-2 falls below the reference threshold voltage, corresponding first signal path blocking element 12-2 will block the transmission of signals on first signal line 14. In this case, even if the other first signal path blocking elements 12-1, 12-3 to 12-5 remain closed, i.e., keep first signal line 14 connected and continue to transfer signals, processing unit 16 will not receive any signal because first signal line 14 is blocked by first signal path blocking element 12-2. Processing unit 16 will then output a warning signal that at least one of at least one electrical plate 4-1 to 4-5 is not operating as intended.

[0044] The processing unit 16 cannot determine which electrical plates 4-1 through 4-5 are not operating as intended; it can only determine that some plates are not operating as intended. However, it should be noted that this information is sufficient because it may be necessary to disassemble the entire battery stack in any event. A more detailed evaluation of the electrical plates 4-1 through 4-5 can be performed after disassembly of the entire stack 2. Alternatively, a more detailed evaluation can be performed before disassembly of the entire battery stack by installing additional evaluation units to individually evaluate each electrical plate. For example, such evaluation units can be attached to each electrical plate 4-1 through 4-5 for further inspection.

[0045] As shown in FIG. 2, the voltage monitoring device 1 may further include voltage fluctuation leveling elements 18-1 to 18-5 to protect the first signal path blocking elements 12-1 to 12-5. The voltage fluctuation leveling elements 18-1 to 18-5 are connected in series between the contact elements 10-1 to 10-5 and the first signal path blocking elements 12-1 to 12-5 and are configured to transmit the voltage of each contact element 10-1 to 10-5 to the first signal path blocking elements 12-1 to 12-5 when the voltage exceeds a leveling threshold voltage. Therefore, voltage fluctuations are filtered and do not affect the downstream signal path blocking elements 12-1 to 12-5. The voltage fluctuation leveling elements 18-1 to 18-5 may be, for example, resistors.

[0046] 3, the voltage monitoring device 1 includes an additional second signal line 20 connected in parallel to the first signal line 14 and also connected to the processing unit 16. The signal carried on the first signal line 14 may have the same origin as the signal carried on the second signal line 20, or may have a different origin, for example a voltage source.

[0047] Each voltage monitoring unit 8-1 to 8-5 includes a second signal path blocking element 22-1 to 22-5, which is arranged on the second signal line 20 and connected in parallel with the respective first signal path blocking element 12-1 to 12-5. Preferably, the first and second signal path blocking elements 12-1 to 12-5 and 22-1 to 22-5 are adapted to different threshold reference voltages.

[0048] 2, each voltage monitoring unit 8-1 to 8-5 may further include a second voltage fluctuation leveling element 24-1 to 24-5 connected in series between the contact element 10-1 to 10-5 and the second signal path blocking element 22-1 to 22-5. Similar to the voltage fluctuation leveling elements 18-1 to 18-5, the second voltage fluctuation leveling elements 24-1 to 24-5 also serve to protect the second signal path blocking elements 22-1 to 22-5 by filtering voltage fluctuations. It should be noted that the voltage fluctuation leveling elements 18-1 to 18-5 and 24-1 to 24-5 are optional and may be omitted.

[0049] The first and second signal lines 14, 20 may be used to provide a staged warning system. This means that the first signal line 14 and the second signal line 20 and their corresponding signal path blocking elements 12-1 to 12-5 and 22-1 to 22-5 are each adapted to a different reference voltage threshold. For example, if the voltage generated by one of the electrical plates 4-1 to 4-5 (e.g., 4-2) falls below a first reference threshold voltage, the corresponding first signal path blocking element 12-2 will block transmission of the first signal because the voltage supplied to the first signal path blocking element 12-2 falls below the required first reference threshold voltage. In this way, signal transmission on the first signal line 14 is blocked, and the processing unit 16 determines that it receives a signal on the second signal line 20 but not on the first signal line 14. The processing unit 16 then outputs a pre-warning signal indicating that one of the electrical plates 4-1 to 4-5 has reached a critical state but is still functional.

[0050] If the voltage generated by the electrical plate 4-2 also falls below the lower second reference threshold voltage, the corresponding second signal path blocking element 22-2 also blocks transmission on the second signal line 20, and the processing unit 16 determines that the battery stack 2 needs to be disassembled and at least one of the electrical plates 4-1 to 4-5 needs to be replaced.

[0051] The voltage monitoring device 1 can be scaled up as needed, since it can include two or more signal lines 14, 20 with corresponding signal path blocking elements. Depending on the number of signal lines, more detailed monitoring with various warning levels can be achieved.

[0052] In summary, the voltage monitoring device described herein can provide a simple and cost-effective method for monitoring the voltage of a battery stack. Instead of monitoring the exact voltage of each electrical plate, it is sufficient to monitor whether any one of the electrical plates in the battery stack is not operating as intended, without more detailed information about the actual plate that is causing the non-operation. [Explanation of symbols]

[0053] 1. Voltage monitoring device 2 Battery stack 4 Electric Plates 6 insulating layer 8 Voltage Monitoring Unit 10 Contact Elements 12 First signal path blocking element 14 First signal line 16 Processing Unit 18 Voltage fluctuation leveling element 20 Second signal line 22 second signal path blocking element 24 Voltage fluctuation leveling element

Claims

1. A voltage monitoring device (1) for a battery stack (2) including a plurality of electrical plates (4) sandwiching an insulating layer (6), the voltage monitoring device (1) being configured to monitor the voltage of at least one electrical plate (4) of the battery stack (2), the voltage monitoring device (1) including at least one voltage monitoring unit (8) having a contact element (10) in contact with the at least one electrical plate (4), 1. A voltage monitoring device (1) comprising a first signal line (14) configured to supply a first signal from a signal source to a processing unit (16), wherein the voltage monitoring unit (8) comprises a first signal path interrupting element (12) arranged on the first signal line (14), the first signal path interrupting element (12) being connected to the contact element (10) and configured to transfer the first signal depending on the voltage present on the at least one electrical plate (4).

2. 2. The voltage monitoring device of claim 1, wherein the first signal path blocking element (12) is configured to forward or block the first signal when a voltage present on the at least one electrical plate (4) exceeds a reference threshold voltage.

3. 3. The voltage monitoring device of claim 1, wherein the first signal is an electrical signal, and the first signal path interrupting element (12) is a relay, an electrical switch, or an electromechanical switch.

4. 4. A voltage monitoring device according to claim 3, wherein the relay is a transistor, in particular a bipolar transistor.

5. 3. The voltage monitoring device according to claim 1, wherein the first signal is an optical signal, and the first signal path interrupting element (12) is an electrical switch or an electromechanical switch.

6. 6. A voltage monitoring device according to any one of claims 1 to 5, wherein the signal source is a current source or a voltage source, or is a first electrical plate (4) of the plurality of electrical plates (4).

7. 7. The voltage monitoring device of claim 1, wherein the voltage monitoring unit (8) includes a voltage fluctuation equalization element (18) arranged between the contact element (10) and the first signal path interruption element (12) and configured to transmit a voltage from the contact element (10) to the first signal path interruption element (12) when the voltage exceeds an equalization threshold voltage.

8. 8. The voltage monitoring device of claim 1, wherein the processing unit is configured to output a warning signal when the first signal is not transferred to the processing unit or when the first signal is transferred to the processing unit.

9. 9. The voltage monitoring device (1) of claim 1, wherein the voltage monitoring device (1) includes a plurality of voltage monitoring units (8), each including a contact element (10) in contact with a respective one of the plurality of electrical plates (4), each including a first signal path interruption element (12) arranged on the first signal line (14), each of the first signal path interruption elements (12) connected to the corresponding contact element (10) and configured to transfer the first signal depending on the voltage present on each of the electrical plates (4), and wherein the first signal path interruption elements (12) of the plurality of voltage monitoring units (8) are connected in series.

10. 10. The voltage monitoring device according to claim 1, wherein the voltage monitoring device (1) includes a second signal line (20) connected in parallel with the first signal line (14), and the voltage monitoring unit (8) includes a second signal path blocking element (22) arranged on the second signal line (20) and connected in parallel with the first signal path blocking element (12).

11. 11. The voltage monitoring device of claim 10, wherein the first signal path blocking element (12) is configured to forward the first signal when the voltage of the at least one electrical plate (4) exceeds a first reference threshold voltage, and the second signal path blocking element (22) is configured to forward or block the second signal when the voltage of the at least one electrical plate (4) exceeds a second reference threshold voltage.

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