Measuring setup and method for detecting a fault affecting a battery

Abstract

The invention relates to a measuring arrangement (10) for a battery (18), comprising a carrier plate (14), an electrical conductor arrangement (20) arranged on the carrier plate (14), and an evaluation unit (36) designed to measure an electrical resistance (R) of at least a part of the conductor arrangement (20) and, depending on this, to detect a specific first fault case (F2). The measuring arrangement (10) includes an electrical resonant circuit (12) arranged on the carrier plate (14), which comprises the electrical conductor arrangement (20) and includes an inductive resonant circuit section (12a) and a capacitive resonant circuit section (12b). The measuring arrangement (10) also includes an excitation unit (32, 34) for exciting the resonant circuit (12) and for detecting a response signal to the excitation of the resonant circuit (12), which is designed to generate a characteristic (G, f). R) of the response signal and, depending on this, to detect the specific first error case (F2) and / or a specific second error case (F1).

Description

[0001] The invention relates to a measuring arrangement for a battery, wherein the measuring arrangement comprises a carrier plate, an electrical conductor arrangement arranged on the carrier plate, and an evaluation unit designed to measure the electrical resistance of at least part of the conductor arrangement and to detect a specific fault condition depending on the measured electrical resistance. The invention further relates to a method for detecting a fault condition affecting a battery.

[0002] Various methods are known from the prior art to detect certain fault cases affecting a battery using a resistance measurement via a conductor arrangement.

[0003] German patent DE 10 2022 201 948 A1 describes a system for monitoring and enhancing the safety of a battery system comprising multiple battery cells. A detection element is positioned outside a cell housing, in close proximity to the cell housing, such that fluid escaping from a vent in the cell housing can be detected at the point of escape. The detection element can be an electrically conductive element, for example, a wire. When a cell outgasses, the temperature of the detection element increases, leading to a change in resistance and eventually to the wire melting. The resulting break in the circuit can then be detected. Furthermore, the system can detect the preceding changes in electrical resistance, thus enabling the early detection of an impending thermal runaway.

[0004] WO 2023 / 006914 A1 describes a fiber composite component that includes a sensor element. An evaluation unit is used to determine changes in the sensor element's properties, such as conductivity. The sensor element can be formed by an electrically conductive structure. The sensor device can determine whether the integrity of the fiber composite component is compromised. If the fiber composite component is mechanically damaged, for example by a stone impact, the component, along with the electrical conductors within it (which are part of the sensor element), can buckle, thus interrupting the circuit. This allows conclusions to be drawn about the integrity of the fiber composite component.

[0005] By analyzing the resistance of an electrical conductor, various fault conditions can be detected with varying degrees of accuracy and reliability. A change in resistance and / or a break in the conductor can have different causes, meaning that analyzing such a resistance value does not always definitively pinpoint the cause. Furthermore, evaluating a resistance value is only of limited use in differentiating fault conditions based on their severity or nature. Therefore, it would be desirable to be able to detect one or more fault conditions, particularly those affecting a battery, more reliably and / or with greater differentiation.

[0006] The object of the present invention is therefore to provide a measuring arrangement and a method that enable the most reliable and / or differentiated detection possible of at least one fault case, which in particular concerns a battery.

[0007] This problem is solved by a measuring arrangement and a method with the features according to the respective independent patent claims.

[0008] Advantageous embodiments of the invention are the subject of the dependent patent claims, the description, and the figures.

[0009] A measuring arrangement according to the invention for a battery comprises a carrier plate, an electrical conductor arrangement arranged on the carrier plate, and an evaluation unit designed to measure an electrical resistance of at least a part of the conductor arrangement and to detect a specific first fault case depending on the measured resistance.The measuring arrangement comprises an electrical resonant circuit arranged on the carrier plate and including the electrical conductor arrangement, wherein the electrical resonant circuit comprises an inductive resonant circuit part and a capacitive resonant circuit part, wherein the measuring arrangement also includes an excitation unit for exciting the resonant circuit and for detecting a response signal to the excitation of the resonant circuit, and wherein the evaluation unit is designed to determine a characteristic of the response signal and, depending on the determined characteristic, to detect the specific first fault case and / or a specific second fault case.

[0010] The measuring arrangement thus comprises a resonant circuit mounted on the carrier plate, which can advantageously be used in two ways to detect a first and / or second fault condition. Firstly, the resonant circuit can be excited and its response signal evaluated to determine a characteristic based on which such a fault condition can be detected. Secondly, part of the resonant circuit can also be used for resistance measurement to detect a fault condition. This can be the same fault condition, which can be detected more reliably due to the dual detection capability, or whose detection can be verified by redundant measurements. Alternatively, it can be an additional, different fault condition, allowing the measuring arrangement to detect different fault conditions and thus enabling a significantly more differentiated detection of fault conditions.Thus, it is advantageous to integrate two sensor concepts into one component or measuring arrangement.

[0011] It is particularly advantageous to use a vehicle underride guard as a mounting plate, or a substrate that can be mounted on such an underride guard. In particular, an underride guard can be a plate-shaped component which, in its intended installation position in a vehicle, can be positioned below a battery in the vehicle's vertical direction and at least partially at a distance from the underside of the battery. Such a battery can be, in particular, a high-voltage battery. In its intended installation position in a vehicle, this battery can be located in an underbody area of ​​such a vehicle. Such a battery can, in particular, comprise several battery modules and / or several battery cells, for example, lithium-ion cells. The battery can optionally also be part of the measuring arrangement.In this case, the support plate is positioned below the battery in a defined direction that corresponds to the vehicle's vertical orientation when installed in a motor vehicle. The support plate can extend perpendicular to this defined direction across the entire battery. The electrical resonant circuit is then located on the side of the support plate facing the battery.

[0012] The mounting plate can be made of an electrically conductive material, for example, a metallic material. In this case, the electrical resonant circuit is electrically insulated on the mounting plate. However, the mounting plate can also be made of an electrically insulating material or have an electrically insulating surface. For example, the mounting plate can be made of a plastic material or a plastic composite material.

[0013] In principle, any section of the electrical resonant circuit can be used for resistance measurement. However, it is preferred that the conductor arrangement, or the part of the conductor arrangement whose resistance is measured, is provided by a portion of the capacitive resonant circuit. This has the advantage that the capacitive resonant circuit can be easily laid over any surface with any geometry. This allows, in principle, any arbitrarily large area of ​​the substrate to be monitored by resistance measurement. Furthermore, despite the large surface area covered by the capacitive resonant circuit, the section used for resistance measurement can be easily designed so that its total resistance under normal conditions (i.e., without any fault present) lies within a desired range, e.g., is as low as possible.This can influence or increase the accuracy in detecting resistance changes, e.g. because very small resistance changes in relation to a small total resistance become more noticeable than in relation to a very large total resistance, so that they can be detected reliably and with high accuracy.

[0014] The excitation unit can be designed to provide the acquired response signal to the evaluation unit for analysis. Furthermore, the excitation unit can be inductively coupled to the inductive resonant circuit section. For example, the excitation unit can include an excitation coil that is inductively coupled to a resonant circuit coil as part of the inductive resonant circuit section. The excitation unit can thus be designed to inductively excite the resonant circuit. Likewise, the response signal, inductively fed back into the excitation unit via the inductive resonant circuit section, can be acquired by the excitation unit and provided to the evaluation unit.

[0015] To excite the circuit, electrical energy can be introduced into the resonant circuit by means of the excitation unit, in particular through its coupling coil. The excitation should be carried out in such a way that the resonant frequency of the circuit is also excited.

[0016] Alternatively, it is also conceivable to provide the resonant circuit with a conductive input by applying a regulator voltage, although this is less preferred. A current flow through the resonant circuit can then be detected as the response signal, for example, using a current sensor. In this case, the excitation unit can be designed to provide such an AC voltage as the excitation voltage at the input of the resonant circuit. However, excitation using an inductively coupled excitation unit eliminates the need for additional sensors to detect the response signal and also simplifies resistance measurement, as will be explained in more detail below.

[0017] According to an advantageous embodiment of the invention, the evaluation unit is designed to detect a deformation of the carrier plate, and / or contact of the carrier plate with a component arranged above the carrier plate at least partially at a distance from the carrier plate, in particular the battery, and / or a break in the conductor arrangement and / or a thermal runaway of a battery cell arranged above the carrier plate as a first fault case, depending on the measured resistance.

[0018] When the carrier plate deforms, the conductor assembly mounted on it stretches accordingly, which in turn changes the conductor resistance. This change can be detected by measuring the resistance. If the carrier plate is deformed so severely, for example towards the battery, that it makes contact with the underside of the battery and, consequently, with the conductor assembly mounted on it, the conductor assembly is also deformed, in particular crushed, which further alters its conductor resistance, especially increasing it. In this case, the change in resistance is significantly greater than in the case of deformation of the carrier plate without direct contact with the component above it, namely the battery. Thus, these two initial failure scenarios can also be distinguished by resistance measurement using different resistance threshold values.A break in the conductor arrangement leads to an infinitely high resistance, which can also be detected by resistance measurement. In particular, this fault condition can then be clearly distinguished from the two fault conditions mentioned above, namely deformation with and without contact. Such a break can, for example, be caused by thermal runaway in a battery cell located above the carrier plate. It is advantageous if the battery cells are arranged relative to the carrier plate in such a way that the accessible cell vents, through which the battery cells can release gases in the event of thermal runaway, face the carrier plate.Hot gas escaping from a thermally continuous battery cell then directly impacts the carrier plate and, in particular, the conductor assembly mounted on it. The conductor assembly is preferably positioned relative to the battery cells such that the portion of the conductor assembly used for resistance measurement is located below the cell vent openings of the battery cells in the direction defined above. The escaping hot gas can thus cause the corresponding conductors of the conductor assembly to melt, which in turn can be detected as a conductor break. Therefore, the aforementioned fault conditions, especially the first type of fault, can be reliably and distinguishably detected by means of resistance measurement.

[0019] Additionally or alternatively, the evaluation unit may be designed to detect a break in the resonant circuit and / or a thermal runaway of a battery cell located above the carrier plate, and / or the presence of liquid on the carrier plate, depending on the characteristics, in particular a resonant frequency of the resonant circuit and / or a quality factor of the response signal, as the first and / or second fault case.

[0020] The evaluation unit can therefore be designed to determine the resonant frequency of the resonant circuit and / or the quality factor of the response signal based on its characteristics. Based on this, the aforementioned fault conditions can be detected. In particular, the presence of liquid on the substrate, especially near the resonant circuit or in direct contact with the electrical resonant circuit, leads to a change in its resonant frequency. Therefore, if the evaluation unit detects a change in the resonant frequency of the resonant circuit, for example, compared to a reference resonant frequency defined for normal conditions, the presence of liquid on the substrate can be inferred.The liquid in question could be, for example, water, particularly cooling water, that has leaked from the battery's cooling system, and / or an electrolyte fluid that has leaked from a battery cell. These two cases can also be advantageously distinguished, for example, by considering the quality of the response signal. Water, for instance, reduces the quality of the response signal, while electrolyte fluid, upon contact with the resonant circuit, does not significantly reduce the quality of the response signal.

[0021] A break in the resonant circuit or thermal runaway of a battery cell can also be detected by evaluating the response signal. Specifically, the battery cells enclosed by the battery should be arranged relative to the resonant circuit as described above, so that hot gas escaping from a battery cell during thermal runaway strikes a part of the resonant circuit. This can cause the resonant circuit to melt at that point, which can then be detected as a break in the circuit because it results in a shift in the resonant frequency. In the case of such a break, a significantly more drastic shift in the resonant frequency of the circuit is to be expected than in the case of liquid being present on the substrate, thus allowing these cases to be distinguished.Furthermore, thermal runaway causes the resonant circuit to heat up, which is primarily reflected in a change, especially a reduction, in the quality of the response signal. This allows a circuit break caused by thermal runaway in a battery cell to be distinguished from other circuit breaks not caused by such thermal runaway.

[0022] Furthermore, certain fault conditions, such as a broken wire or thermal runaway in a battery cell, can be detected based on both the characteristics of the resonant circuit's response signal and resistance measurements. This allows for more reliable detection of these fault conditions, as well as more reliable detection of fault causes and / or a more precise or reliable differentiation between these different fault conditions.

[0023] To detect the aforementioned fault conditions, changes in the respective measured variables are preferably considered. In other words, the first fault condition can be detected, for example, as a function of a measured change in the electrical resistance of a part of the wiring assembly. For this purpose, the resistance can be measured repeatedly or continuously, and the fault condition can be detected accordingly as a function of a change in the resistance value, for example, relative to previous resistance values ​​or an average of previous resistance values. Alternatively, a corresponding reference resistance value can be specified for a defined normal case, i.e., in which none of the fault conditions are present, and the measured electrical resistance value can be compared with this reference resistance value.

[0024] The same applies to the evaluation of the response signal's characteristics. Here, too, it can be arranged that the resonant circuit is repeatedly or continuously excited by the excitation unit, and the corresponding response signal is recorded and evaluated with regard to its characteristics. The characteristics of the response signal can thus also be recorded repeatedly or continuously. A change in the characteristics can, for example, be recorded or evaluated in relation to a previous value of the characteristic or in relation to a reference value for the characteristic, such as a quality factor reference value and / or a reference resonant frequency value.

[0025] Furthermore, not only can the individual measured variables, namely the resistance and / or the characteristics of the response signal, and their changes be considered, but also, for example, their temporal behavior or the duration of their occurrence.

[0026] The quality factor (Q factor) can characterize the quality of the response signal. For example, the Q factor can be defined as the amplitude of the response signal at the (current) resonant frequency of the resonant circuit. The Q factor can also be defined as the ratio of stored energy to thermal energy loss during one oscillation period. Alternatively, the Q factor can be defined as the ratio of the resonant frequency to the bandwidth.

[0027] According to a further advantageous embodiment of the invention, the measuring arrangement is configured such that the resistance measurement, on the one hand, and the excitation of the resonant circuit and the acquisition of the response signal, on the other hand, occur sequentially. Thus, no resistance measurement is performed while the resonant circuit is being excited and the response signal is being acquired, and vice versa. This ensures that the response signal of the resonant circuit is not distorted by the resistance measurement, and conversely, the resistance measurement is not distorted by the excitation of the resonant circuit. This results in more accurate measurement results.

[0028] The measuring setup can be configured to alternate between resistance measurement and "resonant circuit measurement"—that is, excitation of the resonant circuit and recording of the response signal—for example, in a predetermined sequence or specifically in predetermined situations. It is particularly advantageous to differentiate between at least two operating conditions.

[0029] Accordingly, a further advantageous embodiment of the invention is achieved if the measuring arrangement is configured such that, in a first operating mode, which in particular represents driving mode, the resistance is repeatedly measured and, depending on this, repeatedly checked for the presence of the first fault condition. In particular, the characteristics of the resonant circuit's response signal are determined more frequently than in the first operating mode. Resistance measurement allows for the particularly reliable detection of deformations of the carrier plate or contact between the carrier plate and the component located above it. Such deformations are generally caused by external objects striking the underside of the carrier plate, especially the underride guard. This typically occurs only during driving and not, or at least very rarely, when the vehicle is stationary.Therefore, it is advantageous to perform resistance measurements primarily or exclusively during driving operation or in the first operating mode, or at least more frequently than resonant circuit measurements. It can also be provided that, upon detection of the first fault based on resistance measurements and / or at certain predetermined (less frequent) measurement times during the first operating mode, the characteristics of the response signal to excitation of the resonant circuit are also determined and checked for the presence of the first and / or second fault. Thus, if, for example, the first fault—such as deformation of the carrier plate or contact with the component above it—is detected in the first operating mode based on resistance measurements, consequential damage, such as fluid leakage from the battery, can be detected or ruled out by means of a subsequent resonant circuit measurement.The resonant circuit measurement can also be performed occasionally during the first operating mode, for example, to monitor for the presence of liquid in the area of ​​the carrier plate. However, this should preferably be done less frequently than the resistance measurement during the first operating mode.

[0030] Furthermore, it is highly advantageous if the measuring arrangement is configured such that, in a second operating mode—which particularly represents a standstill or parking of the vehicle in which the measuring arrangement is used—the characteristic of the response signal to excitation of the resonant circuit is repeatedly determined and checked for the presence of the first and / or second fault condition. In particular, it can be provided that only resonant circuit measurements are performed in this second operating mode, and no resistance measurements. Thus, for example, even when the vehicle is stationary, such as when parked, stopped at a traffic light, during electrical charging of the vehicle's battery, or similar situations, the carrier plate can be monitored for the presence of liquid.

[0031] This allows for advantageous, targeted measurements adapted to different operating situations using the measuring setup. This enables particularly effective situation-adapted use of the measuring setup and its measurement functionalities.

[0032] According to a further advantageous embodiment of the invention, the capacitive resonant circuit part comprises a pair of conductors with two electrical conductors, each having a first conductor end that is electrically connected or connectable to one end of the inductive resonant circuit part, in particular a coil, and each having a second open conductor end.

[0033] The fact that the first conductor end is connected or connectable to the inductive resonant circuit component means that the first conductor can be permanently connected to the inductive resonant circuit component, e.g., the first coil end, either by hardwiring or by a switch or similar device that can be connected and disconnected as needed. The same applies to the second electrical conductor, or rather its first conductor end, and the inductive resonant circuit component. In the case of a permanent electrical connection, the conductor pair and the coil can be made from a single, continuous wire or conductor, or from separate components connected to each other.

[0034] The conductor pair can be laid out on the carrier plate in any geometry. For example, it can run in a straight line from a starting area of ​​the carrier plate to an end area. It can also be laid out in loops from the starting area to the end area and optionally back again, etc. In particular, several such loops can be provided. The conductor pair can also run in a wave-like, zigzag, or meandering pattern from the starting area to the end area. This arrangement of the conductor pair allows for reliable and flexible coverage of a desired detection area.

[0035] Each conductor in this pair of conductors comprises a first and a second conductor end. The second conductor end is an open end, at least during the resonant circuit measurement. The two second conductor ends are therefore not directly electrically connected to each other, but only indirectly connected, or connectable, via the inductive resonant circuit section. The first conductor ends can be connected, or connectable, to corresponding coil ends of the coil that provides the inductive resonant circuit section.

[0036] According to a further advantageous embodiment of the invention, the evaluation unit is designed to measure the resistance via two taps, one of which is provided on each of the two conductors of the conductor pair. A measuring voltage can be applied between these two taps, for example, by the evaluation unit, and the resulting current flow can be measured. Knowing the applied voltage and the measured current flow, the conductor resistance can be determined as the electrical resistance. The evaluation unit can be connected to these two taps via appropriate measuring leads and disconnected from them. Switches can be provided for this purpose. During the resonant circuit measurement, the two taps should therefore not be electrically connected via external resonant circuit leads or similar, or at most, they should be connected with such a high resistance that this has no influence on the resonant circuit measurement.

[0037] According to a further advantageous embodiment of the invention, the measuring arrangement is configured such that the capacitive resonant circuit section is permanently electrically connected to the inductive resonant circuit section, in particular with each of the two taps being arranged at the respective second end of the two conductors. In the case of resistance measurement, the entire resonant circuit can thus be traversed by a corresponding measuring current. A corresponding measuring voltage can be applied to the two second open ends of the two conductors via the respective taps. This enables a particularly simple and cost-effective design of the measuring arrangement, since very few or even no additional switching elements are required.

[0038] According to a particularly advantageous embodiment of the invention, however, the measuring arrangement comprises at least one or two first switching elements by means of which the capacitive resonant circuit part can be electrically separated from the inductive resonant circuit part, in particular wherein the measuring arrangement is configured so that during the detection of the resistance via the two taps the capacitive resonant circuit part is electrically conductively separated from the inductive resonant circuit part.

[0039] It is further advantageous if the measuring arrangement also includes a second switching element by means of which the two conductors of the conductor pair can be electrically connected, in particular wherein the measuring arrangement is configured such that, during the detection of the resistance via the two taps, the two conductors of the conductor pair are electrically connected by means of the second switching element, in particular wherein one of the two taps is arranged at each of the first ends of the two conductors. The second switching element is then preferably arranged such that it connects the two conductors to each other in the region of their second open ends. However, it can also be provided that the second switching element electrically connects the two first ends of the two conductors, which are then in a state separated from the inductive resonant circuit section, to each other, and the two taps are provided at the second open ends of the conductors.

[0040] Decoupling the inductive resonant circuit section during resistance measurement increases the accuracy of the results. In particular, this reduces the overall resistance of the resistance measurement path, allowing even small changes in resistance to be detected more reliably and accurately. Therefore, it is highly advantageous to decouple the inductive resonant circuit section during resistance measurement using one or two primary switching elements, such as switches. The capacitive resonant circuit section can then be advantageously used for resistance measurement. The taps can be located at either the first two ends or the second two ends, and the other two ends can be electrically connected via the second switching element. This allows both conductors of the wire pair to contribute to the resistance measurement, resulting in highly accurate measurements.

[0041] It is also conceivable that only one of the two conductors of the wire pair is used for resistance measurement. Therefore, a further advantageous embodiment of the invention is achieved if the two taps are arranged at least on a first part of an identical conductor and at a distance from each other, particularly if at least the first part of the conductor can be decoupled from the inductive resonant circuit via a third switching element, and the measuring arrangement is designed such that at least the first part of the conductor is separated from the inductive resonant circuit while the resistance is measured via the taps. Using only a single conductor of the wire pair for resistance measurement reduces complexity and saves on components. In particular, this again allows for the elimination of switching elements.The conductor used for resistance measurement can, in turn, advantageously be decoupled from the inductive resonant circuit section via a corresponding switching element, which is referred to here as the third switching element, in order to further increase the measurement accuracy.

[0042] The control of these switching elements can be handled, for example, by the evaluation unit. This unit can control and switch the corresponding switching elements accordingly, i.e., open or close them, depending on the type of measurement being performed, such as resistance measurement or resonant circuit measurement. Each switching element can therefore have an open state and a closed state and be reversibly transitionable between these states. The switching elements can be, for example, electronically controlled switches such as transistors, MOSFETs, or similar devices.

[0043] Furthermore, the invention also relates to a motor vehicle with a measuring arrangement according to the invention or one of its embodiments.

[0044] The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus or motorcycle. The motor vehicle can be designed as an electric vehicle.

[0045] Furthermore, the invention also relates to a method for detecting a fault case concerning a battery by means of a measuring arrangement comprising a carrier plate, an electrical conductor arrangement arranged on the carrier plate, and an evaluation unit that measures an electrical resistance of at least a part of the conductor arrangement and detects a specific first fault case depending on the measured resistance.The measuring arrangement comprises an electrical resonant circuit arranged on the carrier plate and including the electrical conductor arrangement, wherein the electrical resonant circuit comprises an inductive resonant circuit part and a capacitive resonant circuit, wherein the measuring arrangement has an excitation unit that excites the resonant circuit and detects a response signal to the excitation of the resonant circuit, wherein the evaluation unit determines a characteristic of the response signal and, depending on the determined characteristic, detects the specific first fault case and / or a specific second fault case.

[0046] The advantages described for the measuring arrangement and its embodiments according to the invention apply in the same way to the method according to the invention.

[0047] The invention also includes further developments of the method according to the invention, which have features already described in connection with the further developments of the measuring arrangement according to the invention. For this reason, the corresponding further developments of the method according to the invention are not described again here.

[0048] The invention also includes combinations of the features of the described embodiments. The invention therefore also includes realizations that each exhibit a combination of the features of several of the described embodiments, provided that the embodiments have not been described as mutually exclusive.

[0049] The following are exemplary embodiments of the invention. This is illustrated by: Fig. 1 a schematic representation of the measuring arrangement according to an embodiment of the invention; Fig. 2 a schematic representation of a measuring arrangement in a side view according to an embodiment of the invention; Fig. 3 a schematic side view of a measuring arrangement in the case of external force application according to a further embodiment of the invention; Fig. 4 a schematic representation of an electrical resonant circuit for a measuring arrangement according to an embodiment of the invention; and Fig. 5 a schematic representation of an electrical resonant circuit for a measuring arrangement according to a further embodiment of the invention.

[0050] The exemplary embodiments described below are preferred embodiments of the invention. In these exemplary embodiments, the described components each represent individual features of the invention, which can be considered independently of one another and each further develops the invention independently. Therefore, the disclosure is intended to include combinations of features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0051] In the figures, identical reference symbols denote functionally equivalent elements.

[0052] Fig. Figure 1 shows a schematic representation of a measuring arrangement 10 according to an embodiment of the invention. The measuring arrangement 10 comprises an electrical resonant circuit 12 mounted on a carrier plate 14 (see Figure 1). Fig. 2) is arranged, for example by an underride guard 16 (see Fig. 2) of a motor vehicle. Such a carrier plate 14 is preferably positioned below a battery 18 (see Figure 1) with respect to a defined direction, which in this case corresponds to the z-direction shown. Fig. 3), which can also be part of the measuring arrangement 10, is arranged. The electrical resonant circuit 12 comprises an inductive resonant circuit section 12a and a capacitive resonant circuit section 12b. The resonant circuit 12 also includes a conductor arrangement 20, which in this case is provided by the capacitive resonant circuit section 12b. The inductive resonant circuit section 12a can be provided by a coil 21. The capacitive resonant circuit section 12b is provided by a pair of conductors 22, which comprises a first electrical conductor 22a and a second electrical conductor 22b. Each of these conductors 22a, 22b in turn has a first conductor end 24, which in this example is permanently electrically connected to a respective coil end 28, 30. The coil 21 can therefore comprise the two coil ends 28, 30, each of which is electrically connected to one of the first ends 24 of a respective conductor 22a, 22b.The coil 21 and the electrical conductors 22a, 22b can also be formed in one piece, for example from a single piece of electrical wire. Furthermore, the respective electrical conductors 22a, 22b each include an open second conductor end 26.

[0053] To excite the resonant circuit 12, the measuring arrangement 10 comprises an excitation unit 32, which in this case is provided by a coil 34 inductively coupled to the resonant circuit coil 21. The measuring arrangement 10 also comprises an evaluation unit 36. The excitation unit 32 can be electrically isolated from the coil 34 in the z-direction above it. The excitation unit 32 is designed to excite the resonant circuit 12 and to detect a corresponding response signal. From this response signal, the evaluation unit 36 ​​can extract a characteristic, in particular a quality factor G of the response signal and / or a current resonant frequency f. Rof the resonant circuit 12. Furthermore, the evaluation unit 36 ​​can continuously or repeatedly record this characteristic and, in particular, monitor it for changes in these characteristics. Certain fault conditions can be detected by changes in these characteristics. In the present example, the presence of a liquid 38 in the area of ​​the resonant circuit 12, especially on the support plate 14, is shown as an example of such a fault condition F1. Such a liquid 38 changes the resonance frequency f. Rof the resonant circuit 12, which can thus advantageously be detected by the evaluation unit 36. Furthermore, the quality factor G of the response signal can be used to determine the type of liquid involved, specifically whether it is electrolyte fluid of the battery 18 or cooling water from a cooling device for the battery 18. The operating principle is based on the presence of the capacitive component (capacitor), i.e., the capacitive resonant circuit section 12b, and the inductive component 12a (coil 21). The capacitive component 12b is altered by contamination with specific substances or other environmental influences. This results in a shift of the resonant frequency f. R , which is measured. The measured quantity is, for example, the resonance frequency f. R or additionally or alternatively, the grade G.

[0054] A particular advantage is that part of this resonant circuit 12, namely the conductor arrangement 20, can also be used for resistance measurement. The evaluation unit 36 ​​is therefore also designed to measure the resistance R of at least part or section of this conductor arrangement 20. In this example, two taps 40, 42 are provided on the respective conductors 22a, 22b for measuring the resistance R, specifically in the region of their second ends 26. Thus, the resistance measurement can be performed via these taps 40, 42.

[0055] The resistance measurement is not performed simultaneously with the resonant circuit measurement, i.e., with the recording of the characteristic G and / or f. RThe execution of the respective measurements may depend on a given operating state B1, B2 of the motor vehicle, whereby, for example, a first operating state B1 may represent driving operation of the motor vehicle, and a second operating state B2 may represent a standstill of the motor vehicle or a parking and / or charging of the motor vehicle.

[0056] Because the resonant circuit 12, or a part thereof, can also be used for resistance measurement, significantly more fault cases can be detected using this measuring arrangement 10, and / or fault cases can be detected, verified, and / or recorded in a more differentiated manner. In particular, resistance measurement can be used to detect deformation of the carrier plate 14, contact with the battery 18, and / or even an intrusion, as will be explained in more detail later.

[0057] Fig. Figure 2 shows a schematic representation of the measuring arrangement 10. Fig. Figure 1 shows a schematic side view. The arrangement of the inductive resonant circuit part 12a can be limited to an initial region 14a of the carrier plate 14, while the capacitive resonant circuit part 12b can extend, for example, in a specific direction, in this case in the x-direction, almost over the entire carrier plate 14, for example up to a defined end region 14b of the carrier plate 14.

[0058] In general, the resonant circuit 12, as well as the excitation unit 32, 34, can be designed to be particularly flat. The measuring arrangement 10, in particular the excitation unit 32 and the resonant circuit 12, can therefore provide a planar sensor unit that requires very little installation space in the z-direction.

[0059] Fig. Figure 3 shows a schematic side view of a measuring arrangement 10 according to a further embodiment of the invention. This can be implemented in particular as described above. Here, the battery 18, which can be designed, for example, as a high-voltage battery, is additionally illustrated above the support plate 14, in particular above the underride guard 16. In the present example, an external force is applied to the support plate 14 from below by an object 40 external to the vehicle.This results in contact between the carrier plate 14, in particular a part of the resonant circuit 12, and the underside 18a of the battery 18. This constitutes a second fault condition F2, which can now be detected particularly reliably and advantageously using the aforementioned resistance measurement. This is because such deformation and / or, above all, contact with the battery 18 causes deformation of the conductors 22a, 22b and / or stretching of these conductors, which significantly increases the resistance R. This increase can be reliably detected by the evaluation unit 36 ​​based on the resistance measurement. The operating principle is therefore as follows: The deformation leads to a reduction in the cross-section and an elongation of the wire, resulting in a higher ohmic resistance, which in turn generates a voltage change.The measured quantity can be the ohmic resistance and / or the measured bridge voltage caused by the change in resistance.

[0060] To ensure that the measurements do not influence each other, it is preferred that they be carried out alternately over time, in particular, as already mentioned, preferably depending on the respective operating states B1, B2.

[0061] It is particularly advantageous if the inductive resonant circuit section 12a can be decoupled from the capacitive resonant circuit section 12b in order to avoid negatively affecting the resistance measurement. This can be achieved primarily by the in Fig. 4 and Fig. 5 illustrated versions of the resonant circuit 12 can be implemented particularly advantageously.

[0062] According to the in Fig. In the example shown in Figure 4, the measuring arrangement 10 comprises two first switching elements 48, 50, via which the capacitive resonant circuit part 12b can be decoupled from the inductive resonant circuit part 12a, in particular electrically disconnected, and, if necessary, reconnected to it, i.e., electrically conductively connected. The measuring arrangement 10 also comprises a second switching element 52, via which the second ends 26 of the electrical conductors 22a can be conductively connected and disconnected from each other. The taps 40, 42, via which the resistance measurement is performed, are provided in this example in the region of the first ends 24 of the conductors 22a, 22b. Thus, in this example, three switching elements 48, 50, 52 are required to switch from the resonant circuit measurement to the resistance measurement and vice versa.

[0063] Fig. Figure 5 shows a schematic representation of a resonant circuit 12 for a measuring arrangement according to a further embodiment of the invention. In this example, the measuring arrangement 10 includes a third switch 54, by means of which one of the conductors 22a, 22b, in this example conductor 22b, can be disconnected from the inductive resonant circuit part 12a. The taps 40, 42 for the resistance measurement are now both provided on this single common conductor 22b, one at the first end 24 and the other at the second end 26 of the conductor 22b. In this case as well, the measuring section for the resistance measurement can advantageously be disconnected from the inductive resonant circuit part 12b, but in this example only one switching element 54 is required. Compared to the one in Figure 5, the measuring section 54 is therefore only one switching element 54. Fig. However, in the variant shown in section 4, a slightly weaker resistance signal can be expected.

[0064] Overall, the examples show how the invention can provide a combined wire layout for the detection of deformations and substances as well as thermal runaway.

[0065] The invention enables the combination of two sensor concepts in a single component. An optionally switchable wire layout, providing the electrical resonant circuit, can be mounted on an underbody protection panel beneath a high-voltage battery. The wire layout can be coupled with an evaluation unit for assessing resistance values ​​and changes in the resonant frequency and / or Q factor. By evaluating the resistance value, intrusions through the underbody can be detected (in multiple stages). Very high resistance (wire breakage) indicates a thermal runaway of a cell (ejected particles destroy the wire layout and thus interrupt the circuit). By evaluating the resonant frequency, certain substances (e.g., electrolytes or water) and, furthermore, wire breaks (e.g., triggered by a thermal event) on the wire layout can be detected, indicating a fault in the high-voltage system.The circuit allows both functions to be implemented particularly advantageously in a single component. The wire layout can be adapted for the respective functions by means of one or more switches.

[0066] Ideally, both functions—resistance measurement and resonant circuit measurement—should not operate simultaneously. Therefore, logic for switching between the two is advantageous. Bollard load cases (e.g., driving over a bollard) or special events typically only occur while driving. Since deformations in a plastic underride guard are largely elastic (i.e., only temporary), deformation detection based on resistance measurement can be continuously active while driving. Thus, two operating modes can be defined depending on the status. In operating mode 1, when the vehicle is driving, deformation detection is active. If an event is detected, the system switches to the resonant circuit—i.e., to resonant circuit measurement—for a specific period to detect potential consequential damage, such as leaking fluids or thermal runaway. Regular switching to the resonant circuit for monitoring purposes is also possible.In operating mode 2, in which the vehicle is stationary (parking / charging / idle times (e.g. traffic light)), the resonant circuit is on, i.e., the resonant circuit measurement is active, possibly only at the beginning and / or end of the parking phase, and optionally, e.g., at regular intervals or situationally (e.g., when the vehicle is stopped at a traffic light). QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2022 201 948 A1

[0003] WO 2023 / 006914 A1

[0004]

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