DETECTION OF MOISTURE IN AN ELECTRONIC CIRCUIT

Description

[0001] The present invention relates to an electronic circuit with a moisture detection device, a battery pack for supplying an electrical device with such an electronic circuit, an electrical device with such an electronic circuit or battery pack, and a method for detecting moisture in an electronic circuit. US 2015 / 346127 A1 describes a moisture sensor.

[0002] Moisture penetrating an electronic circuit can cause malfunctions and damage to the electronic circuit or a device containing the electronic circuit. This can have particularly dramatic consequences if, for example, damaged lithium-ion battery cells come into contact with water, which can lead to a violent reaction and, as a result, personal injury.

[0003] It is an object of the present invention to enable simple and reliable detection of moisture in an electronic circuit.

[0004] This object is achieved by the respective subject matter of the independent claims. Advantageous further developments and preferred embodiments are the subject matter of the dependent claims.

[0005] The invention is based on the idea of ​​providing a detection structure in addition to two reference structures connected to corresponding reference potential terminals of the electrical circuit and measuring a voltage between the detection structure and one of the reference structures in order to detect moisture between the detection structure and the other reference structure.

[0006] According to one aspect of the invention, an electronic circuit with a moisture detection device is specified. The moisture detection device has an electrically conductive detection structure arranged in the vicinity of an electrically conductive first reference structure of the electronic circuit, wherein the first reference structure is connected to a first reference potential terminal of the electronic circuit. The moisture detection device has a voltage sensor having a first sensor terminal connected to the detection structure and a second sensor terminal connectable to an electrically conductive second reference structure of the electronic circuit. The second reference structure is connected to a second reference potential terminal of the electronic circuit.The voltage sensor is configured to generate a sensor signal depending on an electrical voltage between the first sensor terminal and the second sensor terminal. The moisture detection device has a switching device configured to selectively disconnect the second sensor terminal from the second reference structure and connect it to the second reference structure. In other words, the switching device is configured to switchably connect the second sensor terminal to the second reference structure or to connect the second sensor terminal to the second reference structure and disconnect the connection.The moisture detection device comprises an evaluation unit configured to detect moisture depending on the sensor signal generated in particular while the second sensor terminal is electrically connected to the second reference structure by the switching device, which electrically couples the first reference structure to the detection structure.

[0007] The first and second reference potential terminals are, in particular, at different electrical potentials. The first and second reference potential terminals of the electronic circuit can serve, for example, to connect the electronic circuit to a voltage source, for example one or more rechargeable battery cells. Alternatively, the first reference potential terminal can be connected to a supply voltage for the electronic circuit and the second reference potential terminal to a ground terminal, or vice versa. The first reference structure is electrically connected directly or indirectly to the first reference potential terminal, just as the second reference structure is electrically connected directly or indirectly to the second reference potential terminal. The reference structures can be, for example, wire connections, conductor tracks, connections or pins of electronic components, electrodes, and so on.The direct or indirect connection of the respective reference structures with the corresponding reference potential connection ensures in particular that the reference structures are each at a defined electrical potential.

[0008] The detection structure can, for example, also be a conductor track, a wire structure, or another electrically conductive structure, which, apart from moisture detection, is irrelevant to the functionality of the electronic circuit. In particular, in the dry state of the electronic circuit—that is, when no moisture couples the detection structure to the first or second reference structure—and the second sensor terminal is separated from the second reference structure, the detection structure is neither directly nor indirectly connected to one of the reference potential terminals. The electrical potential of the detection structure is therefore generally not fixed or floating.

[0009] In particular, the sensor signal is a direct measure of the voltage between the first and second sensor terminals. If the switching device electrically connects the second sensor terminal to the second reference structure, the sensor signal is a direct measure of the voltage between the detection structure and the second reference structure.

[0010] The fact that the moisture electrically couples the first reference structure to the detection structure can be understood in particular in such a way that the moisture at least temporarily establishes an electrical connection between the first reference structure and the detection structure.

[0011] Due to the floating electrical potential of the detection structure in the dry state of the circuit, an electrical voltage is present between the sensor terminals at the time the detection structure is electrically connected to the second reference structure by the switching device, the magnitude of which is generally unknown. However, since the voltage sensor necessarily has a finite internal resistance, charge equalization occurs between the detection structure and the second reference structure during continuous electrical connection. This results in the voltage between the sensor terminals dropping to a predeterminable value after a characteristic time. Simply put, the voltage between the sensor terminals drops to zero or essentially zero within a certain time.

[0012] The situation is different, however, when moisture couples the detection structure to the first reference structure. In this case, the detection structure receives a more or less defined electrical potential from the first reference structure. In other words, the first reference structure recharges the detection structure when charges flow from the detection structure via the voltage sensor to the second reference structure, or vice versa. This leads to the voltage between the sensor terminals either rising again if it had already dropped accordingly, or not falling to the value expected for the dry state at all, or falling more slowly than expected for the dry state.Accordingly, the evaluation unit can determine whether the moisture is located between the first reference structure and the detection structure by evaluating the sensor signal, in particular by evaluating the temporal course of the sensor signal, by comparing it with a predetermined target behavior in the dry state of the electronic circuit.

[0013] This advantageously eliminates the need for a dedicated power supply for the detection structure. Furthermore, it is not necessary to know the detection structure's inherent resistance precisely. Likewise, it is not necessary to generate a current flow through the detection structure and measure the change in this current flow to detect moisture. Compared to applying a dedicated voltage and measuring the corresponding current, fewer components are required, namely, only a voltage sensor instead of a current sensor and a voltage source. Corresponding additional electrical connections are also eliminated. This can also have advantages in terms of installation space or the area required on a circuit board of the electronic circuit.

[0014] The moisture that couples the first reference structure to the detection structure can, for example, be water penetrating from the outside. However, it can also be a liquid that is provided within the electronic circuit or within an electrical device or battery pack in or with which the electronic circuit can be used. For example, the electronic circuit can be part of a battery pack with multiple battery cells. In this case, the moisture can correspond, for example, to liquid electrolyte leaking from a damaged battery cell.

[0015] If the evaluation unit determines that moisture is present based on the sensor signal, the evaluation unit can initiate an appropriate measure, particularly a risk-reducing measure, such as deactivating the electronic circuit, interrupting a corresponding current flow, and / or generating a warning signal, etc. For this purpose, the evaluation unit can also control other components of the electronic circuit or, if applicable, the electrical device or battery pack.

[0016] The electronic circuit or moisture detection device can, for example, comprise an analog-to-digital converter (ADC), which contains or represents the voltage sensor. Accordingly, the sensor terminals can correspond to inputs of the ADC.

[0017] According to at least one embodiment of the electronic circuit, the detection structure is electrically separated from the first reference structure and from the second reference structure in a dry state of the electronic circuit when the second sensor terminal is separated from the second reference structure by the switching device.

[0018] The dry state of the electronic circuit corresponds in particular to a state in which neither the first reference structure nor the second reference structure is coupled to the detection structure by moisture. The dry state of the electronic circuit can also be considered a desired state, for example.

[0019] As a result, the electrical potential of the detection structure in the dry state is independent of the first reference potential at the first reference potential terminal and the second reference potential at the second reference potential terminal. Moisture eliminates this independence, resulting in the detectability of moisture as described.

[0020] According to at least one embodiment, the evaluation unit is configured to detect the sensor signal, while the second sensor terminal is connected to the second reference structure in order to detect the humidity.

[0021] The evaluation of the sensor signal can vary depending on the design of the electronic circuit. For example, the switching device can essentially permanently electrically connect the second reference structure to the second sensor terminal, so that after a certain decay time, the electrical voltage between the sensor terminals is zero. The evaluation unit can then monitor the sensor signal to determine whether the sensor signal or the voltage between the sensor terminals rises above a predetermined limit. If this is the case, the presence of moisture can be determined.

[0022] In other embodiments, the evaluation unit can cyclically establish and disconnect the electrical connection between the second sensor terminal and the second reference structure, so that in the dry state, a drop in the corresponding voltage can be observed each time the second sensor terminal is reconnected to the second reference structure. The evaluation unit can then compare the voltage curve with a target curve to determine, for example, whether the voltage drops more slowly than expected in the dry state and / or whether the voltage has dropped to at least a corresponding limit value after a predetermined time in order to detect moisture.

[0023] According to at least one embodiment, the evaluation unit is configured to record the temporal profile of the sensor signal while the second sensor terminal is connected to the second reference structure, in particular by means of the switching device, and to detect the humidity depending on the temporal profile.

[0024] According to at least one embodiment, the switching device is configured to connect the second reference structure to the second sensor terminal at a first starting time, wherein the second reference structure is in particular not connected to the second sensor terminal immediately before the first starting time.

[0025] According to at least one embodiment, the evaluation unit is configured to compare the sensor signal at a first measurement time with a predefined threshold value, with a predefined first time interval between the first start time and the first measurement time. The evaluation unit is configured to detect the humidity depending on the result of the comparison.

[0026] For this purpose, the switching device comprises, in particular, a switching element arranged between the second reference structure and the second sensor connection. This switching element can be opened to separate the second reference structure from the second sensor connection and closed to connect the second reference structure to the second sensor connection. The switching device also comprises a control unit that can control the switching element accordingly. The evaluation unit can contain the control unit, or vice versa, or the two units can be configured independently of one another.

[0027] If the evaluation unit determines, based on the evaluation of the sensor signal, in particular based on the comparison with the limit value, that the voltage between the first and second sensor terminals has not dropped at least to the limit value at the first measurement time, the presence of moisture can be concluded. Alternatively, the evaluation unit can also determine whether the voltage initially falls below the limit value and has already exceeded it again at the first measurement time. This can also indicate the presence of moisture.

[0028] According to at least one embodiment, the evaluation unit is configured to compare the temporal profile of the sensor signal after the first start time with a predetermined target profile and to detect the humidity depending on a result of this comparison.

[0029] According to at least one embodiment, the moisture detection device contains an electrically conductive further detection structure arranged in an environment of the second reference structure of the electronic circuit. The moisture detection device has a further voltage sensor having a further first sensor terminal connected to the further detection structure. A second further sensor terminal of the further voltage sensor is connectable to the first reference structure. The further voltage sensor is configured to generate a further sensor signal depending on an electrical voltage between the first further sensor terminal and the second further sensor terminal. The switching device is configured to selectively disconnect the second further sensor terminal from the first reference structure and connect it to the first reference structure.The evaluation unit is configured to detect moisture depending on the further sensor signal generated while the second further sensor terminal is connected to the first reference structure, which moisture electrically couples the second reference structure to the further detection structure.

[0030] The evaluation unit can therefore evaluate the sensor signal and the second sensor signal. Optionally, the evaluation unit can have two independent evaluation subunits, which can also be spatially separated from each other if necessary. A first evaluation subunit can then receive the sensor signal, and a second evaluation subunit can receive the additional control signal.

[0031] The switching device can, for example, have a further switching element which is arranged between the first reference structure and the second further sensor connection in order to establish or separate the connection between the first reference structure and the second further sensor connection.

[0032] The statements regarding the detection structure and the voltage sensor can be transferred analogously to embodiments with the further detection structure and the further voltage sensor, wherein the roles of the first reference structure and the second reference structure are exchanged in this regard.

[0033] According to at least one embodiment, in particular an embodiment in which the moisture detection device does not have the further detection structure and the further voltage sensor, the switching device is configured to selectively separate the second sensor terminal from the first reference structure and to connect it to the latter, for example by means of a correspondingly arranged further switching element of the switching device.

[0034] The switching device is in particular configured to connect the second sensor terminal either to the first reference structure or to the second reference structure.

[0035] This allows the above statements regarding the detection of moisture, which electrically couples the first reference structure to the detection structure, to be transferred to the detection of moisture, which electrically couples the second reference structure to the detection structure. Therefore, a single detection structure can advantageously be used to detect both situations.

[0036] According to at least one embodiment, the switching device is configured to disconnect the second sensor terminal from the first reference structure and to connect the second sensor terminal to the second reference structure during a first measuring cycle.

[0037] According to at least one embodiment, the switching device is configured to disconnect the second sensor terminal from the second reference structure and to connect the second sensor terminal to the first reference structure during a second measuring cycle following, for example immediately following, the first measuring cycle.

[0038] In other words, the second sensor terminal is connected to the second reference structure and disconnected from the first reference structure during the first measurement cycle and / or the second sensor terminal is disconnected from the second reference structure and connected to the first reference structure during the second measurement cycle.

[0039] Accordingly, by evaluating the sensor signal, the evaluation unit can detect the humidity that couples the first reference structure to the detection structure during the first measurement cycle, and the humidity that couples the second reference structure to the detection structure during the second measurement cycle. Further analog first and second measurement cycles can alternate, allowing both situations to be detected alternately.

[0040] The first measurement cycle lasts, for example, from the first start time to a first end time, with the first measurement time being between the first start time and the first end time. Accordingly, the second measurement cycle can last from a second start time to a second end time, with a second measurement time being between the second start time and the second end time, with a predetermined second time interval in particular between the second start time and the second measurement time.

[0041] The evaluation unit can, for example, compare the sensor signal at the second measurement time with a predetermined further limit value and, depending on the result of this comparison, detect the moisture that couples the second reference structure to the detection structure.

[0042] The further possibilities for detecting the moisture, which couples the first reference structure with the detection structure, can also be transferred accordingly to the detection of the moisture, which couples the second reference structure with the detection structure.

[0043] According to at least one embodiment, the evaluation unit is configured to acquire the sensor signal while the second sensor terminal is connected to the first reference structure, in particular during the second measurement cycle, in order to detect the humidity that electrically couples the second reference structure to the detection structure. In particular, the evaluation unit can be configured to acquire a temporal profile of the sensor signal while the second sensor terminal is connected to the first reference structure and to detect the corresponding humidity depending on the temporal profile.

[0044] According to at least one embodiment, the evaluation unit is configured to initiate a risk-reducing measure when the moisture that electrically couples the first reference structure to the detection structure has been detected.

[0045] According to at least one embodiment, the evaluation unit is configured to initiate the risk-reducing measure when the moisture has been detected which electrically couples the second reference structure to the detection structure or the further detection structure.

[0046] Initiating the risk-reducing measure may, for example, involve generating or triggering a warning signal and / or generating or triggering a control signal for another switching element to interrupt a current flow through the electronic circuit, or the like. Initiating the risk-reducing measure may also involve deactivating the electronic circuit and / or an electrical device and / or a battery pack that is connected to the electronic circuit or contains the electronic circuit.

[0047] According to at least one embodiment, the evaluation unit is configured to initiate an interruption of an electrical connection of the first reference potential terminal to the first reference structure and / or an electrical connection of the second reference potential terminal to the second reference structure in order to initiate the risk-reducing measure.

[0048] For this purpose, the electronic circuit, the moisture detection device or the switching device can have switching elements that can be controlled by the evaluation unit.

[0049] According to a further aspect of the invention, a battery pack for supplying an electrical device with electrical energy is specified. The battery pack has at least one battery cell, in particular a lithium-ion battery cell. The at least one battery cell has a first electrode and a second electrode. The battery pack has an electronic circuit according to the invention. The first reference potential terminal of the electronic circuit is connected directly or indirectly to the first electrode, and the second reference potential terminal is connected directly or indirectly to the second electrode of the battery pack.

[0050] According to at least one embodiment of the battery pack, the electronic circuit contains a battery management system for the battery pack.

[0051] According to at least one embodiment, the electronic circuit contains at least one switching element for interrupting a discharge current from the at least one accumulator cell to the electrical device and / or at least one switching element for interrupting a charging current from a charger to the at least one accumulator cell.

[0052] The risk-reducing measure may then include, for example, interrupting the discharge current and / or the charging current.

[0053] According to a further aspect of the invention, an electrical device with an electronic circuit according to the invention and / or with a battery pack according to the invention is specified.

[0054] The electrical device can be configured, for example, as a power tool or an electrical household appliance. The electrical device can also be configured as an electrically powered vehicle, in particular a small vehicle, such as an electrically powered bicycle or scooter, or the like.

[0055] According to a further aspect of the invention, a method for detecting moisture in an electronic circuit is specified. In this case, a second sensor terminal of a voltage sensor, in particular of the electronic circuit, is connected, in particular by means of a switching device of the electronic circuit, to an electrically conductive second reference structure of the electronic circuit, wherein the second reference structure is connected to a second reference potential terminal of the electronic circuit. A sensor signal is generated by the voltage sensor as a function of a voltage between a first sensor terminal of the voltage sensor and the second sensor terminal.The first sensor connection is connected to an electrically conductive detection structure of the electronic circuit, and the detection structure is arranged in the vicinity of an electrically conductive first reference structure of the electronic circuit. Depending on the sensor signal, moisture is detected, in particular by means of an evaluation unit of the electronic circuit, which electrically couples the first reference structure to the detection structure.

[0056] Further embodiments of the method according to the invention follow directly from the various embodiments of the electronic circuit according to the invention, the battery pack according to the invention, and the electrical device according to the invention, and vice versa. In particular, an electronic circuit according to the invention can be configured to carry out a method according to the invention or it carries out such a method.

[0057] The invention is explained in more detail below using specific embodiments and associated schematic drawings. In the figures, identical or functionally equivalent elements may be provided with the same reference numerals. The description of identical or functionally equivalent elements may not necessarily be repeated for different figures.

[0058] The figures show: Fig. 1 is a schematic representation of an exemplary embodiment of an electronic circuit according to the invention; Fig. 2 is a schematic representation of a voltage curve; Fig. 3 is a schematic representation of a further exemplary embodiment of an electronic circuit according to the invention; Fig. 4 is a schematic representation of further voltage curves; Fig. 5 is a schematic representation of a further exemplary embodiment of an electronic circuit according to the invention; Fig. 6a is a schematic representation of an exemplary embodiment of a battery pack according to the invention; Fig. 6b is a schematic representation of a contact arrangement of the battery pack from Fig. 6a ; Fig. 7 shows a schematic sectional view through a further exemplary embodiment of a battery pack according to the invention; and Fig. 8 shows a schematic sectional view through a battery cell of a further exemplary embodiment of a battery pack according to the invention.

[0059] In Fig. 1 An electronic circuit 1 according to the invention is shown schematically. The circuit 1 has a first reference potential terminal 9a and a second reference potential terminal 9b, which can be connected, for example, to corresponding electrodes of a voltage source. For example, the electronic circuit 1 can be part of a battery pack 15 (see Fig. 6a ) with several accumulator cells 18 (see Fig. 7 ). The accumulator cells 18 can, for example, be connected in series and / or parallel and have a common first electrode and a common second electrode for outputting an output voltage. In this case, the first electrode can be connected to the first reference potential terminal 9a and the second electrode to the second reference potential terminal 9b. However, the electronic circuit 1 can also be used in other configurations, wherein the reference potential terminals 9a, 9b are at different electrical potentials.

[0060] The circuit 1 has an electrically conductive first reference structure 4a, which is connected to the first reference potential terminal 9a, and an electrically conductive second reference structure 4b, which is connected to the second reference potential terminal 9b. The reference structures 4a, 4b can, for example, correspond to conductor tracks or wiring of the circuit 1. The circuit 1 can have a plurality of further electronic components, which for the sake of clarity are shown in Fig. 1 are not shown. The electronic circuit 1 also has a moisture detection device 2. The function of the moisture detection device 2 is independent of the specific design of the other components of the circuit 1, so that in the following, reference is made only to the reference structures 4a, 4b and the reference potential terminals 9a, 9b.

[0061] The moisture detection device 2 contains an electrically conductive detection structure 3, which can also be configured, for example, as a wire or conductor track, and which is arranged in the vicinity of the first reference structure 4a. The moisture detection device 2 also has a voltage sensor 5 with a first sensor terminal 6a, which is connected to the detection structure 3, and with a second sensor terminal 6b, which can be connected to or disconnected from the second reference structure 4b via a switching element 8. For this purpose, the moisture detection device 2 has a control unit 10, which can control the switching element 8 accordingly to establish or disconnect the connection. The switching element 8 can contain a transistor, for example a field-effect transistor.

[0062] The moisture detection device 2 also has an evaluation unit 7, which is connected to the voltage sensor 5 or, in some embodiments, can contain the voltage sensor 5. In various embodiments, the evaluation unit 7 and the control unit 10 can also be designed as a common control and evaluation unit.

[0063] The voltage sensor 5 can generate a sensor signal that represents the voltage between the two sensor terminals 6a, 6b. If the switching element 8 is closed, so that the second reference structure 4b is connected to the second sensor terminal 6b, the sensor signal represents the voltage U between the detection structure 3 and the second reference structure 4b. A corresponding voltage U curve is shown schematically in Fig. 2 as a function of time t.

[0064] In the example of Fig. 2 For example, the switching element 8 is initially open and is closed by means of the control unit 10 at a starting time t 0. In a dry state of the electronic circuit 1, the detection structure 3 is electrically separated from the first reference structure 4a and from the second reference structure 4b, provided the switching element 8 is open. Therefore, the electrical potential of the detection structure 3 is generally undetermined, i.e., floating. Accordingly, at time t 0, a voltage drop occurs between the detection structure 3 and the second reference structure 4b. However, due to the finite internal resistance of the voltage sensor 5, this voltage drops over time and, in the dry state of the electronic circuit 1, reaches, for example, approximately zero at a later time t 1.

[0065] However, if there is moisture 11 in the electronic circuit 1, which, as in Fig. 1 As indicated, the first reference structure 4a is electrically connected to the detection structure 3, at least a partial charge equalization can take place between the detection structure 3 and the first reference structure 4a. Since the reference structures 4a, 4b are at different electrical potentials, this leads to a voltage greater than zero between the sensor terminals 6a, 6b. Accordingly, the voltage U can rise again after the time t 1, as in Fig. 2 If the connection of the second sensor terminal 6b with the second reference structure 4b is established by closing the switching element 8 when the moisture 11 is already present, the voltage U may not drop as in Fig. 2 indicated to zero, but remains at a higher value. A corresponding curve or value of the voltage U can be compared with an expected target curve or target value of the voltage by means of the evaluation unit 7 in order to detect the humidity 11.

[0066] In Fig. 3 A further exemplary embodiment of the electronic circuit 1 according to the invention is shown schematically, which is based on the embodiment of the Fig. 1 based.

[0067] In the embodiment of the Fig. 3 The evaluation unit 7 and the control unit 10 are not shown for reasons of clarity. The switching element 8 can, for example, be designed or act as a changeover switch. The control unit 10 can then control the switching element 8 such that the second sensor connection 6b is connected to the first reference structure 4a and is separated from the second reference structure, or vice versa. Alternatively, the moisture detection device 2 can have a switching element 8 as with respect to Fig. 1 explained, as well as a further switching element (not shown), which can also be controlled by the control unit 10 and is arranged between the first reference structure 4a and the detection structure 3. Accordingly, the control unit 10 can control the switching element 8 and the further switching element such that the switching element 8 is closed and the further switching element is open, or vice versa.

[0068] Thus, the control unit 10 can optionally connect the detection structure 3 to the first reference structure 4a and the second reference structure 4b. If the detection structure 3 is connected to the second reference structure 4b and separated from the first reference structure 4a, the evaluation unit 7 can measure the moisture 11 between the first reference structure 4a and the detection structure 3 as with respect to Fig. 1 described. If, however, the detection structure 3 is connected to the first reference structure 4a and separated from the second reference structure 4b, the evaluation unit 7 can detect a moisture 11 which electrically connects the second reference structure 4b to the detection structure 3. In this case, the statements regarding Fig. 1 und Fig. 2 analogue.

[0069] In various embodiments, the control unit 10 can cyclically control the switching element 8 and the further switching element such that during successive measurement cycles, the first reference structure 4a or the second reference structure 4b is alternately connected to the detection structure 3 in order to alternately perform the corresponding moisture detection. A corresponding voltage curve between the two sensor terminals 6a, 6b is shown schematically in Fig. 4 The voltage curve U as a function of time t corresponds to the voltage curve between the second reference structure 4b and the detection structure 3 and the voltage curve U' as a function of time t corresponds to the voltage curve between the first reference structure 4a and the detection structure 3. As with respect to Fig. 2 carried out, the second reference structure 4b is connected to the detection structure 3 at time t 0 , so that the voltage U drops from a finite value to a value close to zero at time t 1 . At time t 1 , for example, the second reference structure 4b is then separated from the detection structure 3 and the detection structure 3 is connected to the first reference structure 4a. Accordingly, the voltage U' assumes a finite value, which drops over time until a further time t 2 , for example, to a value close to zero. At time t 2 , the detection structure 3 is again separated from the first reference structure 4a and connected to the second reference structure 4b, so that the voltage curve of the voltage U repeats itself between t 2 and a subsequent time t 3 as described. It should be noted that this sketched curve of the voltages U, U' corresponds to the dry state of the circuit 1.Corresponding deviations, as with regard to . Fig. 2 described, the evaluation unit 7 accordingly allows conclusions to be drawn about the moisture 11 between the detection structure 3 and one of the reference structures 4a, 4b.

[0070] In Fig. 3 An optional resistor 14 is shown, which is connected in series with the internal resistance of the voltage sensor 5. This allows the electrical resistance between the sensor terminals 6a, 6b to be further increased in order to delay the described voltage drop. In this way, the voltage curve can be adapted according to the specific requirements. Such a resistor 14 can also be used in embodiments according to Fig. 1 be provided.

[0071] Furthermore, Fig. 3 an optional inductive element 12a and an optional resistor 13a are connected in series between the first reference structure 4a and the detection structure 3. By appropriately selecting the inductance of the inductive element 12a and the ohmic resistance of the resistor 13a, the coupling can be adjusted accordingly in order to adjust the temporal course of the voltage during the measuring intervals for detecting the moisture 11. This can also be done in embodiments according to Fig. 1 be provided optionally. Furthermore, as in Fig. 3 As shown, a further inductive element 12b may be connected in series with a further resistor 13b between the detection structure 3 and the second reference structure 4b. These have a function analogous to that described with respect to the inductive element 12a and the resistor 13a.

[0072] In Fig. 5 another exemplary embodiment of the electronic circuit 1 according to the invention is shown, which is based on the embodiment of the Fig. 1 is based on.

[0073] For the sake of clarity, the sensor connections 6a, 6b as well as the control unit 10 and the evaluation unit 7 as well as the switching element 8 are not shown.

[0074] In the embodiment of the Fig. 5 The moisture detection device 2 has a further detection structure 3', which is arranged in an environment of the second reference structure 4b. The moisture detection device 2 also contains a further voltage sensor 5', which has a further first sensor connection connected to the further detection structure 3', and a second sensor connection switchably connected to the first reference structure 4a. For this purpose, the moisture detection device 2 has a further switching element (not shown) that can be controlled by the control unit 10 in order to connect the first reference structure 4a to the further second sensor connection or to disconnect it from it. The functioning of the detection structure 3' or the voltage sensor 5' is analogous to the functioning of the detection structure 3 and the voltage sensor 5, as with respect to Fig. 1 described.

[0075] According to the embodiment of the Fig. 5 Thus, the moisture 11 that couples the detection structure 3 to the first reference structure 4a can be detected by evaluating the sensor signal of the voltage sensor 5 as described. Moisture 11 that couples the further detection structure 3' to the second reference structure 4b can be detected in an analogous manner by evaluating a further sensor signal of the further voltage sensor 5' by the evaluation unit 7.

[0076] In Fig. 6a is a schematic illustration of an exemplary embodiment of a battery pack 15 according to the invention, which has an electronic circuit 1 according to the invention, as it is described, for example, with regard to the Fig. 1 bis Fig. 5 was explained.

[0077] The battery pack 15 has at least one battery cell 18 (see Fig. 7 ), wherein a first electrode of the accumulator cells 18 is connected to the first reference potential terminal 9a and a second electrode of the accumulator cells 18 is connected to the second reference potential terminal 9b.

[0078] The battery pack 15 can also have two or more external contacts 16 for connecting the battery pack 15 to an electrical device. A first of the external contacts 16 is connected to the first reference potential terminal 9a, and a second of the external contacts 16 is connected to the second reference potential terminal 9b. The external contacts 16 represent potential points for moisture penetration into the battery pack 15 and thus into the electrical circuit 1.

[0079] In Fig. 6b A possible arrangement of the detection structure 3 of the circuit 1 with respect to the external contacts 16 is schematically shown. For example, a part of the detection structure 3 can be arranged between adjacent external contacts 16 in order to be able to detect moisture accordingly.

[0080] In Fig. 7 1 shows a sectional view through a further exemplary embodiment of a battery pack 15 according to the invention. The battery pack 15 can, for example, contain a circuit board 17 that carries a battery management system for the battery pack 15. Furthermore, the circuit board 17 can partially carry the electronic circuit 1 or the moisture detection device 2. The detection structure 3 can, for example, have one or more wire loops that are guided through the region of the battery pack 15 in which the battery cells 18 are arranged. The detection structure 3 can, for example, run in a meandering shape between the individual battery cells 18. In this way, moisture that penetrates into the region of the battery cells 18 and is therefore of particular safety relevance can be detected.

[0081] In Fig. 8 1 shows a schematic sectional view through a rechargeable battery cell 18 of a battery pack 15 according to the invention. The rechargeable battery cell 18 has a housing 19, which forms a negative electrode of the rechargeable battery cell 18 and is connected, for example, to the first reference potential terminal 9a. Furthermore, the rechargeable battery cell 18 has a current interruption element 20, also referred to as a CID (Current Interruption Device), which is electrically insulated from the housing 19 by an insulation element 21 of the rechargeable battery cell 18. The current interruption element 20 can correspond to a positive electrode of the rechargeable battery cell 18 and can be connected, for example, to the second reference potential terminal 9b.

[0082] Fig. 8 also shows another exemplary arrangement of the detection structure 3, which can also be designed as a wire loop structure here. The detection structure 3 is guided, for example, such that it runs near the current interruption element 20 and the housing 19, for example, between the housing 19 and the current interruption element 20. This allows moisture to be detected at particularly critical locations on the battery pack 15.

[0083] For example, the detection structure 3 can be embedded in a further insulation element 22, which is designed, for example, to be porous or sponge-like, so that moisture can penetrate through the electrical insulation element 22 to the detection structure 3, but the detection structure 3 is nevertheless electrically insulated from the housing 19 and the current interruption element 20. BEZUGSZEICHENLISTE:

[0084] 1Circuit 2Moisture detection device 3, 3'Detection structures 4a, 4bReference structures 5, 5'Voltage sensors 6a, 6bSensor connections 7Evaluation unit 8Switching element 9a, 9bReference potential connections 10Control unit 11Moisture 12a, 12Inductive elements 13a, 13b, 14Resistors 15Battery pack 16External connections 17PCB 18Battery cells 19Housing 20Current interruption element 21, 22Insulation elements

Claims

1. Electronic circuit (1) comprising a humidity detection device (2), the humidity detection device (2) comprising - an electrically conductive detection structure (3) arranged in an environment of an electrically conductive first reference structure (4a) of the electronic circuit (1), wherein the first reference structure (4a) is connected to a first reference potential terminal (9a) of the electronic circuit (1); - a voltage sensor (5) comprising a first sensor terminal (6a), which is connected to the detection structure (3), and comprising a second sensor terminal (6b), which is connectable to an electrically conductive second reference structure (4b) of the electronic circuit (1), which is connected to a second reference potential terminal (9b) of the circuit (1), wherein the voltage sensor (5) is configured to generate a sensor signal depending on an electric voltage between the first sensor terminal (6a) and the second sensor terminal (6b); - a switching device (8, 10), which is configured to selectively disconnect the second sensor terminal (6b) from the second reference structure (4b) and connect it thereto, and - an evaluation unit (7) configured to detect depending on the sensor signal humidity (11) which electrically couples the first reference structure (4a) to the detection structure (3).

2. Electronic circuit (1) according to claim 1, wherein the evaluation unit (7) is configured to capture the sensor signal, while the second sensor terminal (6b) is connected to the second reference structure (4b) in order to detect the humidity (11).

3. Electronic circuit (1) according to any one of the preceding claims, wherein the evaluation unit (7) is configured to capture a temporal course of the sensor signal, while the second sensor terminal (6b) is connected to the second reference structure (4b), and to detect the humidity (11) depending on the temporal course.

4. Electronic circuit (1) according to any one of the preceding claims, wherein - the switching device (8, 10) is configured to connect the second reference structure (4b) to the second sensor terminal (6b) at a first starting time; - the evaluation unit (7) is configured to compare the sensor signal with a predetermined threshold value at a first measurement time point, wherein a predetermined first time interval lies between the first starting time and the first measurement time point; and - the evaluation unit (7) is configured to detect the humidity (11) depending on a result of the comparison.

5. Electronic circuit (1) according to any one of the preceding claims, wherein - the humidity detection device (2) comprises an electrically conductive further detection structure (3'), which is arranged in an environment of the second reference structure (4b) of the electronic circuit (1); - the humidity detection device (2) comprises a further voltage sensor (5') comprising a first further sensor terminal, which is connected to the further detection structure (3'), and comprising a second further sensor terminal, which is connectable to the first reference structure (4a), wherein the further voltage sensor (5') is configured to generate a further sensor signal depending on an electric voltage between the first further sensor terminal and the second further sensor terminal; - the switching device (8, 10) is configured to selectively disconnect the second further sensor terminal from the first reference structure (4a) and connect it thereto; and - the evaluation unit (7) is configured to detect depending on the further sensor signal humidity (11) which electrically couples the second reference structure (4b) to the further detection structure (3').

6. Electronic circuit (1) according to any one of claims 1 to 4, wherein the switching device (8, 10) is configured to selectively disconnect the second sensor terminal (6b) from the first reference structure (4a) and connect it thereto.

7. Electronic circuit (1) according to claim 6, wherein the switching device (8, 10) is configured - to disconnect the second sensor terminal (6b) from the first reference structure (4a) and connect it to the second reference structure (4b) during a first measuring cycle; and / or - to disconnect the second sensor terminal (6b) from the second reference structure (4b) and connect it to the first reference structure (4a) during a second measuring cycle.

8. Electronic circuit (1) according to any one of claims 6 or 7, wherein the evaluation unit (7) is configured to capture the sensor signal, while the second sensor terminal (6b) is connected to the first reference structure (4a) in order to detect humidity (11), which electrically couples the second reference structure (4b) to the detection structure (3).

9. Electronic circuit (1) according to any one of the preceding claims, wherein the evaluation unit (7) is configured to initiate a risk-reducing measure if the humidity (11), which electrically couples the first reference structure (4a) to the detection structure (3), was detected.

10. Electronic circuit (1) according to claim 9, wherein the evaluation unit (7) is configured to initiate an interruption of an electric connection of the first reference potential terminal (9a) to the first reference structure (4a) and / or an electric connection of the second reference potential terminal (9b) to the second reference structure (4b) in order to initiate the risk-reducing measure.

11. Battery pack (15) for supplying an electric appliance with electric energy, the battery pack (15) comprising - at least one accumulator cell (18) comprising a first electrode (19) and a second electrode (20); - an electronic circuit (1) according to any one of the preceding claims, wherein the first reference potential terminal (9a) is connected to the first electrode (19) and the second reference potential terminal (9b) is connected to the second electrode (20).

12. Electric appliance comprising an electronic circuit (1) according to any one of claims 1 to 10 or comprising a battery pack (15) according to claim 11.

13. Method for detecting humidity (11) in an electronic circuit (1) according to any one of claims 1 to 10, wherein - a second sensor terminal (6a) of a voltage sensor (5) is connected to an electrically conductive second reference structure (4b) of the circuit (1), wherein the second reference structure (4b) is connected to a second reference potential terminal (9b) of the circuit (1): - by the voltage sensor (5) a sensor signal depending on a voltage between a first sensor terminal (6a) of the voltage sensor (5), which is connected to an electrically conductive detection structure (3) of the circuit (1), and the second sensor terminal (6b) is generated, wherein the detection structure (3) is arranged in an environment of an electrically conductive first reference structure (4a) of the circuit (1); and - depending on the sensor signal humidity (11), which electrically couples the first reference structure (4a) to the detection structure (3), is detected.

14. Method according to claim 13, wherein - the second sensor terminal (6b) during a first measuring cycle is disconnected from the first reference structure (4a) and connected to the second reference structure (4b) and the humidity (11), which electrically couples the first reference structure (4a) to the detection structure (3), is detected depending on the sensor signal captured during the first measuring cycle; and / or - the second sensor terminal (6b) during a second measuring cycle is disconnected from the second reference structure (4b) and connected to the first reference structure (4a) and humidity (11), which electrically couples the reference structure (4b) to the detection structure (3), is detected depending on the sensor signal captured during the second measuring cycle.