Method for monitoring battery cells and circuit device

Abstract

A circuit device (10) for monitoring a battery cell is designed to receive a first measurement signal representing the cell voltage of the battery cell. The first measurement signal is supplied to a main monitoring channel (20) of the circuit device (10) (the main monitoring channel includes a first analog-to-digital converter (ADC) (24)) and to a redundant monitoring channel (30) of the circuit device (10) (the redundant monitoring channel includes a second ADC (34). A reference signal is determined based on a first output signal (U_MAIN) of the main monitoring channel (20) and a second output signal (U_AUX) of the redundant monitoring channel (30). If the first output signal (U_MAIN) is less than a specified first voltage value and exceeds a specified second voltage value, the reference signal is compared with a specified first trigger threshold (TH1). However, if the first output signal (U_MAIN) is greater than or equal to the specified first voltage value or less than or equal to the specified second voltage value, the reference signal is compared with a specified second trigger threshold (TH2).

Description

Technology Field

[0001] The present invention relates to a method and circuit device for monitoring a rechargeable battery cell. The rechargeable battery cell is placed in a rechargeable battery, particularly in a rechargeable traction battery of an electric vehicle. The present invention also relates to a monitoring system, a rechargeable battery system, and a vehicle. Background Technology

[0002] With the electrification of drivetrains, accuracy requirements for battery monitoring are becoming increasingly stringent to improve the driving range and operational safety of electric vehicles, such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs). A critical factor here is the measurement accuracy of cell voltage monitoring. High Automotive Safety Integrity Levels (ASIL), such as Class C or D, require that cell voltage be available as a highly accurate measured value even in the event of undetected errors. Higher cell voltage measurement accuracy allows the traction battery to operate close to its cell voltage limits without risk, thereby increasing the driving range achievable with the same battery capacity. The performance of semiconductor devices used for battery monitoring has already significantly improved in recent years. However, due to high safety requirements, measurement circuits (e.g., analog-to-digital converters that convert recorded voltage sensor signals) must be partially redundant. Voltage sensor signals are compared. An inevitable disturbance factor, namely ripple disturbance, occurs when measuring cell voltage.

[0003] It is desirable to set the trigger threshold that signals an error in the battery monitoring circuit such that these acceptable ripple disturbances are not interpreted as errors by the battery monitoring circuit. In the worst case, if the trigger threshold is exceeded, an emergency stop of the drive train occurs, but at least the service life counter of the traction battery increases.

[0004] Due to the actual tolerances of the components of the filter structure upstream of the two ADCs, it is impossible to completely filter or suppress ripple disturbances. Therefore, the trigger threshold must be set correspondingly high, so the remaining maximum ripple disturbance determines the battery's driving range. A high trigger threshold, for example, shortens the battery charging process prematurely, preventing the battery from being fully charged.

[0005] The object of the present invention is to provide a method and circuit device for monitoring a rechargeable battery cell that contributes to increasing the driving range of a vehicle having a specific battery capacity.

[0006] The above objective is achieved by the features of the independent patent claim. Advantageous improvements of the invention are presented in the dependent claim.

[0007] According to a first embodiment, the objective is achieved by a method for monitoring a rechargeable battery cell of a rechargeable battery. A first step includes receiving a first measurement signal representing the cell voltage of a rechargeable battery cell in a circuit device comprising a main monitoring channel and a redundant monitoring channel. The first measurement signal is supplied to a main monitoring channel comprising a first analog-to-digital converter (ADC) and supplied to a redundant monitoring channel comprising a second ADC. The first ADC performs analog-to-digital conversion of the first measurement signal and provides a first digital output signal representing the cell voltage of the rechargeable battery cell. The second ADC performs analog-to-digital conversion of a signal including the first measurement signal and provides a second digital output signal.

[0008] The first output signal of the main monitoring channel and the second output signal of the redundant monitoring channel are taken as a basis for determining a comparison signal. If the first output signal is less than a specified first voltage value and exceeds a specified second voltage value, the comparison signal is compared with a specified first trigger threshold, and if the comparison signal is greater than the first trigger threshold, a first error signal is provided to the evaluation unit. On the other hand, if the first output signal is greater than or equal to a specified first voltage value or less than or equal to a specified second voltage value, the comparison signal is compared with a specified second trigger threshold, and if the comparison signal is greater than the second trigger threshold, a second error signal is provided to the evaluation unit. In this case, the first voltage value is greater than the second voltage value, and the first trigger threshold has a magnitude greater than the second trigger threshold.

[0009] By implementing two different trigger thresholds, the driving range of a rechargeable battery can be increased without changing the hardware.

[0010] This utilizes the fact that the current flowing and the resulting ripple disturbance differ depending on the operating range of the rechargeable battery. In the normal operating range of the rechargeable battery, each cell of the rechargeable battery exceeds the lower voltage, which includes the lowest allowable cell voltage—that is, the lower threshold cell voltage limit plus a first voltage value (e.g., about 0.1 V)—and each cell of the rechargeable battery is below the upper voltage, which includes the maximum allowable cell voltage—that is, the upper threshold cell voltage limit minus a second voltage value (e.g., about 0.1 V). Since a high current flows in the normal operating range of the rechargeable battery, severe ripple disturbance occurs. Therefore, to prevent high ripple disturbance from causing a false alarm, the trigger threshold is set to a higher level in the normal operating range of the rechargeable battery.

[0011] In the critical operating range, when the rechargeable battery operates near the critical cell voltage, only a low charging current (at the upper cell voltage limit) or a low discharging current (at the lower cell voltage limit) flows, and consequently only minor ripple disturbances may occur, a low trigger threshold is selected.

[0012] In at least one advantageous configuration according to the first embodiment, the designated first voltage value corresponds to the value obtained by subtracting the safety margin voltage value from the upper threshold cell voltage limit value, and the designated second voltage value corresponds to the value obtained by adding the safety margin voltage value to the lower threshold cell voltage limit value.

[0013] In at least one advantageous configuration according to the first embodiment, the direction of the current flowing to the rechargeable battery cell is taken as a basis for suppressing or ignoring the second error signal.

[0014] When a rechargeable battery operates at or near the upper cell voltage limit but is discharging rather than charging, very large currents and consequently large ripple disturbances may occur. However, since the discharge current cannot overload the cell at the upper cell voltage limit, exceeding the second trigger threshold for the relevant current direction can be ignored.

[0015] If a rechargeable battery is operating at or near the lower cell voltage limit but is charging rather than discharging, very large currents and consequently large ripple disturbances may occur. However, since the charging current cannot over-discharge the cell at the lower cell voltage limit, exceeding the threshold for the relevant current direction can be ignored.

[0016] In at least one advantageous configuration according to the first embodiment, the signal is identical to the first measurement signal, and the second output signal represents the cell voltage of the rechargeable battery cell. This allows for a simple comparison. However, common mode errors cannot be detected.

[0017] In at least one advantageous configuration according to the first embodiment, the first ADC of the main monitoring channel and the second ADC of the redundant monitoring channel use the same reference voltage provided by the reference voltage source used by the two ADCs for their respective analog-to-digital conversions. The signal includes a differential signal representing the difference between the supply voltage or reference voltage of the second ADC and the provided first measurement signal. The second output signal represents a level-changed cell voltage signal. In this case, determining a comparison signal based on the first output signal and the second output signal includes the steps of adding the first output signal and the second output signal, subtracting a set value of the supply voltage of the second ADC if the level change of the cell voltage signal is caused by the supply voltage, and subtracting the reference voltage if the level change of the cell voltage signal is caused by the reference voltage.

[0018] Using a common reference voltage reduces manufacturing costs and saves space for circuit devices, and thus enables the detection of reference voltage errors. Consequently, the circuit device also detects common-mode errors (common-mode errors of the reference voltage), eliminating the need for any additional safety devices. Therefore, no additional safety devices are required.

[0019] According to a second embodiment, the above objective is achieved by a circuit device for monitoring a rechargeable battery cell of a rechargeable battery. The circuit device includes a main monitoring channel including a first analog-to-digital converter (ADC) and a redundant monitoring channel including a second ADC. The circuit device has an associated comparison circuit, or the circuit device includes a comparison unit.

[0020] The circuit device is designed to receive a first measurement signal representing the cell voltage of a rechargeable battery cell. The circuit device is designed to make the first measurement signal available on a main monitoring channel and a redundant monitoring channel. A first ADC is designed to perform analog-to-digital conversion of the first measurement signal and provide a first output signal representing the cell voltage of the rechargeable battery cell. A second ADC is designed to perform analog-to-digital conversion of a signal including the first measurement signal and provide a second output signal.

[0021] The comparison unit is designed to determine a comparison signal based on a first output signal of a main monitoring channel and a second output signal of a redundant monitoring channel. The comparison unit is designed to compare the comparison signal with a specified first trigger threshold when the first output signal is less than a specified first voltage value and exceeds a specified second voltage value, and to provide a first error signal to an evaluation unit when the comparison signal is greater than the first trigger threshold. Additionally, the comparison unit is designed to compare the comparison signal with a specified second trigger threshold when the first output signal is greater than or equal to a specified first voltage value or less than or equal to a specified second voltage value, and to provide a second error signal to an evaluation unit when the comparison signal is greater than the second trigger threshold.

[0022] In this case, the first voltage value is greater than the second voltage value, and the first trigger threshold has a size greater than the second trigger threshold.

[0023] In at least one advantageous configuration according to the second embodiment, the comparison unit is designed to take a provided current measurement signal indicating the direction of the current flowing to the rechargeable battery cell as a basis for suppressing the output of the second error signal.

[0024] In at least one advantageous configuration according to the second embodiment, the signal is identical to the first measurement signal, and the second output signal represents the cell voltage of the rechargeable battery cell.

[0025] In at least one advantageous configuration according to the second embodiment, the first ADC of the main monitoring channel and the second ADC of the redundant monitoring channel are designed to use the same reference voltage provided by a reference voltage source for their respective analog-to-digital conversions. The signal includes a differential signal representing the difference between the supply voltage or reference voltage of the second ADC and the provided first measurement signal. The second output signal represents a level-changed cell voltage signal. In this case, the step of determining a comparison signal based on the first output signal and the second output signal comprises:

[0026] -- Step of adding the first output signal and the second output signal,

[0027] -- When a level change in the cell voltage signal is caused by the supply voltage, a step of subtracting the set value of the supply voltage of the second ADC,

[0028] -- If a level change in the cell voltage signal is caused by the reference voltage, it includes a step of subtracting the reference voltage.

[0029] The above objective is achieved by a monitoring system for a rechargeable battery cell according to a third embodiment. The monitoring system comprises a circuit device and a control unit according to a first embodiment, wherein the control unit is designed to take a digital cell voltage signal provided by the circuit device and representing the current cell voltage of the rechargeable battery cell as a basis for specifying a next trigger threshold to a comparison unit of each circuit device, wherein the next trigger threshold is a first trigger threshold when the digital cell voltage signal is less than a specified first voltage value and exceeds a specified second voltage value, and a second trigger threshold when the digital cell voltage signal is greater than or equal to the specified first voltage value or less than or equal to the specified second voltage value.

[0030] The above objective is achieved by a rechargeable battery system comprising, according to a fourth embodiment, a rechargeable battery comprising at least one rechargeable battery cell, a circuit device according to a second embodiment for each of all or at least some of the rechargeable battery cells, and a control unit, wherein the control unit is designed to take a digital measurement signal provided by each circuit device and representing the current cell voltage of each rechargeable battery cell as a basis for specifying a next trigger threshold to a comparison unit of each circuit device, wherein the next trigger threshold is a first trigger threshold when the digital cell voltage signal is less than a specified first voltage value and exceeds a specified second voltage value, and a second trigger threshold when the digital cell voltage signal is greater than or equal to the specified first voltage value or less than or equal to the specified second voltage value.

[0031] The above objective is achieved by a vehicle comprising a rechargeable battery system according to the fourth embodiment according to the fifth embodiment.

[0032] Therefore, the selective configuration of the first and second modes can be applied to other modes and can have a corresponding effect.

[0033] Exemplary embodiments of the present invention are described in more detail below based on schematic drawings. In the drawings, the same reference numerals are used for elements having essentially the same function, but these elements do not need to be identical in all details.

[0034] The description of the subject matter presented in this specification is not limited to individual specific embodiments.

[0035] To the extent that it is technically reasonable, features of various exemplary embodiments may be combined with one another to form additional exemplary embodiments. For example, variations or modifications described for one of the exemplary embodiments may also apply to other exemplary embodiments unless otherwise specified. Brief explanation of the drawing

[0036] FIG. 1 illustrates an exemplary block diagram of one exemplary embodiment of a circuit device for monitoring a rechargeable battery cell. FIG. 2 illustrates an exemplary block diagram of another exemplary embodiment of a circuit device for monitoring a rechargeable battery cell. Specific details for implementing the invention

[0037] When it is stated that one element is "connected" or "combined" to another element, it is understood that this element is directly connected or combined with the other element, or that an intermediate element may exist. Conversely, when it is stated that one element is "directly" "connected" or "combined" to another element, no intermediate element exists. Other expressions used to describe relationships between elements (e.g., "between" versus "directly between," "adjacent to" versus "directly adjacent to," etc.) must be interpreted in the same way.

[0038] The function of the circuit device (10) for monitoring a rechargeable battery cell is described below in relation to FIG. 1, where this figure is a simplified representation of the circuit of the present invention in which many basic components have been omitted for clarity.

[0039] FIG. 1 illustrates an exemplary block diagram of one exemplary embodiment of a circuit device (10) for monitoring a rechargeable battery cell of a rechargeable battery (the rechargeable battery cell and the rechargeable battery are not shown in FIG. 1). The rechargeable battery preferably comprises a plurality of rechargeable battery cells connected in parallel and / or series. The rechargeable battery is, for example, in the form of a rechargeable traction battery for a vehicle.

[0040] A rechargeable battery cell is connected to a circuit device (10), and the input side of the circuit device (10) receives a first cell potential signal (Ucell_p) and a second cell potential signal (Ucell_c) from the indirectly or directly rechargeable battery cell through a preprocessing unit.

[0041] The circuit device (10) includes a main monitoring channel (20) including a first analog-to-digital converter (ADC) (24) and a redundant monitoring channel (30) including a second ADC (34). Additionally, the circuit device (10) includes, for example, a comparison unit (40). Alternatively, the comparison unit (40) may be part of an evaluation unit (50).

[0042] The circuit device (10) is preferably in the form of an integrated circuit within a semiconductor chip. In particular, the semiconductor chip may include a number of such circuit devices (10), and thus a number of rechargeable battery cells can be monitored using the semiconductor chip.

[0043] The input side of the main monitoring channel (20) includes, for example, an analog first filter (22). A first ADC (24) is connected downstream of the first filter (22). For example, the analog first filter (22) of the main monitoring channel (20) is connected directly or indirectly to a rechargeable battery cell. The analog first filter (22) is used to process cell potential signals (Ucell_p, Ucell_n) received from the rechargeable battery cell.

[0044] For example, a digital low-pass filter (26) is connected downstream of the first ADC (24). For example, the output of the digital low-pass filter (26) provides a filtered digital cell voltage signal (UC) representing the cell voltage of the connected rechargeable battery cell to an evaluation unit (50). The evaluation unit (50) may be a control unit associated with the circuit device (10) or a higher-level computing unit.

[0045] The input side of the redundant monitoring channel (30) of the circuit device (10) includes, for example, an analog second filter (32). A second ADC (34) is connected downstream of the second filter (32). The analog second filter (32) of the redundant monitoring channel (30) is connected, for example, directly or indirectly to a rechargeable battery cell. The analog second filter (32) is used to signal process cell potential signals (Ucell_p, Ucell_n) received from the rechargeable battery cell.

[0046] In an optional configuration, the first discrete hardware filter (28) and the second discrete hardware filter (38) are connected upstream of the circuit device (10), the first discrete hardware filter (28) is connected upstream of the first filter (22) of the main monitoring path (20), and the second discrete hardware filter (38) is connected upstream of the second filter (32) of the redundant monitoring path.

[0047] The input of the first ADC (24) has a first input terminal that receives a first measurement signal (Uin_p) representing the potential of the positive electrode of the rechargeable battery cell, and a second input terminal that receives a second measurement signal (Uin_n) representing the potential of the negative electrode of the rechargeable battery cell.

[0048] The first ADC (24) includes, for example, a first level converter. The first level converter is designed to form a first cell potential difference between a first measurement signal (Uin_p) and a second measurement signal (Uin_n). The first cell potential difference may also be referred to as a cell voltage (Ucell).

[0049] The first ADC (24) further includes a converter unit designed to perform an actual analog-to-digital conversion of the cell voltage (Ucell) and to provide a first digital output signal (U_MAIN) at the output of the converter unit.

[0050] The input of the second ADC (34) has a first input terminal that receives a first measurement signal (Uin_p) representing the potential of the positive electrode of the rechargeable battery cell, and a second input terminal that receives a second measurement signal (Uin_n) representing the potential of the negative electrode of the rechargeable battery cell.

[0051] The second ADC (34) includes, for example, a first level converter. The first level converter is designed to form a first cell potential difference between a first measurement signal (Uin_p) and a second measurement signal (Uin_n). The first cell potential difference may also be referred to as a cell voltage (Ucell).

[0052] The first ADC (34) further includes a converter unit designed to perform an actual analog-to-digital conversion of the cell voltage (Ucell) and to provide a second digital output signal (U_AUX) at the output of the converter unit.

[0053] Accordingly, the first ADC (24) and the second ADC (34) receive a first measurement signal representing the cell voltage of a rechargeable battery cell. The first ADC (24) and the second ADC (34) each perform an analog-to-digital conversion of the first measurement signal and provide a first output signal (U_MAIN) or a second output signal (U_AUX) at the output. To determine whether the first ADC (24) is operating normally, the two output signals (U_MAIN, U_AUX) are compared with each other. For example, a comparison signal is determined that indicates the difference between the two output signals (U_MAIN, U_AUX).

[0054] An additional step is to check whether the comparison signal meets the criteria for estimating an error. That is, for example, if the comparison signal representing the difference between two output signals (U_MAIN, U_AUX) exceeds a trigger threshold, an error is detected.

[0055] However, since disturbances—more precisely, ripple disturbances, particularly those dependent on the flowing current—can distort the measurement signal, these disturbances are considered when selecting the trigger threshold.

[0056] Accordingly, if the first output signal (U_MAIN) is less than a specified first voltage value and exceeds a specified second voltage value, the comparison signal is compared with a specified first trigger threshold (TH1), wherein the first voltage value represents the value obtained by subtracting a margin value (e.g., 0.1V) from the threshold upper cell voltage and the second voltage value represents the value obtained by adding another margin value (e.g., 0.1V) to the threshold lower cell voltage. If the comparison signal is greater than the first trigger threshold (TH1), a first error signal (ERR1) is provided to the evaluation unit (50).

[0057] On the other hand, if the first output signal (U_MAIN) is greater than or equal to a specified first voltage value or less than or equal to a specified second voltage value, the comparison signal is compared with a specified second trigger threshold (TH2), and if the comparison signal is greater than the second trigger threshold (TH2), a second error signal (ERR2) is provided to the evaluation unit (50).

[0058] For example, the first trigger threshold (TH1) has a magnitude of 25mV, and the second trigger threshold (TH2) has a magnitude of 12mV. This results in a range gain of 26mV for a given battery size.

[0059] Preferably, when the rechargeable battery is operating at or near the upper cell voltage limit but is discharging rather than charging, the second error signal (ERR2) is suppressed. Additionally, when the rechargeable battery is operating at or near the lower cell voltage limit but is charging rather than discharging, the second error signal (ERR2) is suppressed.

[0060] Alternatively, the evaluation unit (50) can transmit information specifying the current direction to the comparison unit (40). Thus, the comparison unit (40) can immediately mask errors when the current direction is not important. For example, the evaluation unit (50) can transmit an additional flag to the comparison unit (40).

[0061] FIG. 2 illustrates an exemplary block diagram of another exemplary embodiment of a circuit device (10) for monitoring a rechargeable battery cell of a rechargeable battery.

[0062] Unlike the circuit device (10) shown in Fig. 1, the first ADC (24) and the second ADC (34) use the same reference voltage source.

[0063] Additionally, the second ADC (34) of FIG. 2 includes a second level converter. The second level converter is designed to form a second cell potential difference between a second measurement signal (Uin_n) and a first measurement signal (Uin_p), wherein the second measurement signal (Uin_n) forms a minuend and the first measurement signal (Uin_p) forms a subtrahend. The second level converter adds the supply voltage (VCC) of the second ADC (34) and the second cell potential difference to the second ADC (34) to produce a differential signal (U diff It is additionally designed to provide ).

[0064] Alternatively, the second level converter adds the reference voltage (VREF) used by the two ADCs (24, 34) for analog-to-digital conversion and the second cell potential difference to the second ADC (34) to produce a differential signal (U diff It is designed to provide ).

[0065] The second ADC (34) is a differential signal (U diff It includes a converter unit designed to perform actual analog-to-digital conversion of ) and, in this case, provide a second output signal (U_AUX) representing a level-changed cell voltage signal to the output of the converter unit.

[0066] The converter units of the first ADC (24) and the second ADC (34) may be the same or different. In particular, the second ADC (34) may have lower resolution or a longer settling time, as it is sufficient for comparisons to be performed only at specific time intervals. This enables a cost-effective implementation while still ensuring the necessary reliability.

[0067] The first ADC (24) and the second ADC (34) have a cell voltage (U) based on the same reference voltage (VREF) for both ADCs (24, 34). cell ) or differential signal (U diff It is designed to perform analog-to-digital conversion of ).

[0068] The comparison unit (40) of the circuit device (10) is designed to determine each comparison value according to a specified comparison function based on a digital first cell voltage signal (U_MAIN) and a digitally level-changed second output signal (U_AUX).

[0069] The comparison function includes, in particular when the supply voltage (VCC) is used for level change of the second ADC (34), the value obtained by subtracting the set value (VCC_set) of the supply voltage of the second ADC (34) from the sum of the digital first output signal (U_MAIN) and the digitally level-changed second output signal (U_AUX).

[0070] Therefore, in each case, the digital comparison mechanism transmits the resulting comparison value:

[0071] U_delta = U_MAIN + U_AUX - VCC Formula (1a)

[0072] When the reference voltage (VREF) is used for level changes of the second ADC (34), the comparison function includes, in particular, the value obtained by subtracting the reference voltage (VREF) from the sum of the first output signal (U_MAIN) and the second output signal (U_AUX).

[0073] In this case, the digital comparison mechanism transmits the resulting comparison value for each case:

[0074] U_delta = U_MAIN + U_AUX - VREF formula (1b)

[0075] The first ADC (24) and the second ADC (34) use the same reference voltage (VREF). If the reference voltage (VREF) deviates by 10% or more due to an error, the first ADC (24) determines the following cell voltage for the rechargeable battery cell:

[0076] U_MAIN = 1.1 * U cell Formula (2)

[0077] And the second ADC (34) determines the next level-changed cell voltage when the supply voltage (VCC) is used for level change:

[0078] U_AUX = 1.1 * VCC_act - 1.1 * U cell Formula (3a)

[0079] Here U cell is the measured cell voltage of the rechargeable battery cell, and VCC_act is the actual or real value of the supply voltage.

[0080] When a reference voltage (VREF) is used for level change, the second ADC (34) determines the level-changed cell voltage:

[0081] U_AUX = 1.1*VREF - 1.1*U cell Formula (3b).

[0082] Assuming that the supply voltage (VCC) is used for level change in the second ADC (34) and that the set value (VCC_set) and the actual value (VCC_act) of the supply voltage are equal as follows,

[0083] VCC_set = VCC_act = VCC Formula (4)

[0084] The comparison unit (40) checks the following comparison values:

[0085] U_delta = U_MAIN + U_AUX - VCC = 0.1*VCC Formula (5a).

[0086] For example, if the supply voltage is VCC = 5V, this corresponds to 0.5V.

[0087] When the reference voltage (VREF) is used for level change in the second ADC (34), the comparison value is as follows:

[0088] U_delta = U_MAIN + U_AUX - VREF = 0.1*VREF Formula (5b).

[0089] Then, each comparison value is compared with a first trigger threshold (TH1) or a second trigger threshold (TH2) as described in relation to Figure 1.

[0090] Trigger thresholds (TH1, TH2) are specified, for example, by an evaluation unit (50). The evaluation unit (50) is designed to take a digital cell voltage signal (UC), which is provided by the circuit device (10) and represents the current cell voltage of a rechargeable battery cell, as a basis for specifying a first trigger threshold (TH1) or a second trigger threshold (TH2) to the comparison unit (40). In particular, if the digital cell voltage signal (UC) is less than a specified first voltage value and exceeds a second voltage value, the first trigger threshold (TH1) is specified. If the digital cell voltage signal (UC) is greater than or equal to the specified first voltage value, the second trigger threshold (TH2) is specified. If the digital cell voltage signal (UC) is less than or equal to the specified second voltage value, the second trigger threshold (TH2) is likewise specified. Explanation of the symbols

[0091] 10: Circuit device 20: Main monitoring channel 22: Analog First Filter 24: 1st ADC 26: Digital Filter 30: Redundant monitoring channels 32: Analog Second Filter 34: 2nd ADC 40: Comparison Unit 50: Evaluation Unit ERR1: First error signal ERR2: Second error signal TH1: 1st Trigger Threshold TH2: Second trigger threshold U_MAIN: First output signal U_AUX: Second output signal UC: Digital cell voltage signal

Claims

Claim 1 A method for monitoring a rechargeable battery cell of a rechargeable battery, comprising: receiving a first measurement signal representing the cell voltage of the rechargeable battery cell by a circuit device (10) including a main monitoring channel (20) and a redundant monitoring channel (30); supplying the first measurement signal to a main monitoring channel (20) including a first analog-to-digital converter (ADC) (24) and supplying it to a redundant monitoring channel (30) including a second ADC (34); the first ADC (24) performing analog-to-digital conversion of the first measurement signal and providing a first output signal (U_MAIN) representing the cell voltage of the rechargeable battery cell; the second ADC (34) performing analog-to-digital conversion of a signal including the first measurement signal and providing a second output signal (U_AUX); and determining a comparison signal based on the first output signal (U_MAIN) of the main monitoring channel (20) and the second output signal (U_AUX) of the redundant monitoring channel (30). A method comprising: a step of, when the first output signal (U_MAIN) is less than a specified first voltage value and exceeds a specified second voltage value, comparing the comparison signal with a specified first trigger threshold (TH1), and when the comparison signal is greater than the first trigger threshold (TH1), providing a first error signal (ERR1) to an evaluation unit (50); and a step of, when the first output signal (U_MAIN) is greater than or equal to the specified first voltage value or less than or equal to the specified second voltage value, comparing the comparison signal with a specified second trigger threshold (TH2), and when the comparison signal is greater than the second trigger threshold (TH2), providing a second error signal (ERR2) to the evaluation unit (50), wherein the first voltage value is greater than the second voltage value and the first trigger threshold (TH1) has a magnitude greater than the second trigger threshold (TH2). Claim 2 A method according to claim 1, wherein the designated first voltage value corresponds to a value obtained by subtracting the safety margin voltage value from the threshold upper cell voltage value, and the designated second voltage value corresponds to a value obtained by adding the safety margin voltage value to the threshold lower cell voltage value. Claim 3 A method according to claim 1 or 2, wherein the direction of the current flowing through the rechargeable battery cell is taken as a basis for suppressing or ignoring the second error signal (ERR2). Claim 4 A method according to claim 1 or 2, wherein the signal for which analog-to-digital conversion is performed by the second ADC (34) is the same as the first measurement signal, and the second output signal (U_AUX) represents the cell voltage of the rechargeable battery cell. Claim 5 In claim 1 or 2, - the first ADC (24) of the main monitoring channel (20) and the second ADC (34) of the redundant monitoring channel (30) use the same reference voltage provided by the reference voltage source used by the two ADCs (24, 34) for their respective analog-to-digital conversions, - the signal for which analog-to-digital conversion is performed by the second ADC (34) includes a differential signal representing the difference between the supply voltage of the second ADC (34) or the reference voltage and the provided first measurement signal, and the second output signal (U_AUX) represents a level-changed cell voltage signal, - the step of determining the comparison signal based on the first output signal (U_MAIN) and the second output signal (U_AUX) comprises: -- adding the first output signal (U_MAIN) and the second output signal; -- subtracting a set value of the supply voltage of the second ADC (34) when the level change of the cell voltage signal is caused by the supply voltage; and -- the level of the cell voltage signal A method comprising the step of subtracting the reference voltage when a change occurs due to the reference voltage. Claim 6 A circuit device (10) for monitoring a rechargeable battery cell of a rechargeable battery, wherein the circuit device (10) includes a main monitoring channel (20) including a first analog-to-digital converter (ADC) (24) and a redundant monitoring channel (30) including a second ADC (34), and the circuit device (10) includes a comparison unit (40), wherein the circuit device (10) receives a first measurement signal representing the cell voltage of the rechargeable battery cell and is designed to make the first measurement signal available in the main monitoring channel (20) and the redundant monitoring channel (30), wherein the first ADC (24) is designed to perform analog-to-digital conversion of the first measurement signal and provide a first output signal (U_MAIN) representing the cell voltage of the rechargeable battery cell, wherein the second ADC is designed to perform analog-to-digital conversion of a signal including the first measurement signal and provide a second output signal (U_AUX), and wherein the comparison unit (40) is the main A comparison signal is designed to be determined based on a first output signal (U_MAIN) of a monitoring channel (20) and a second output signal (U_AUX) of a redundant monitoring channel (30), and the comparison unit (40) is designed to: -- compare the comparison signal with a designated first trigger threshold (TH1) when the first output signal (U_MAIN) is less than a designated first voltage value and exceeds a designated second voltage value, and provide a first error signal (ERR1) to an evaluation unit (50) when the comparison signal is greater than the first trigger threshold (TH1), and - compare the comparison signal with a designated second trigger threshold (TH2) when the first output signal (U_MAIN) is greater than or equal to the designated first voltage value or less than or equal to the designated second voltage value, and provide a second error signal (ERR2) to the evaluation unit (50) when the comparison signal is greater than the second trigger threshold (TH2), and the first voltage value is greater than the second voltage value, andA circuit device (10) having a first trigger threshold (TH1) that is larger than the second trigger threshold (TH2). Claim 7 In claim 6, the comparison unit (40) is designed to take a provided current measurement signal indicating the direction of the current flowing to the rechargeable battery cell as a basis for suppressing the output of the second error signal (ERR2), circuit device (10). Claim 8 A circuit device (10) according to claim 6 or 7, wherein the signal for which analog-to-digital conversion is performed by the second ADC (34) is the same as the first measurement signal, and the second output signal (U_AUX) represents the cell voltage of the rechargeable battery cell. Claim 9 In claim 6 or 7, - the first ADC (24) of the main monitoring channel (20) and the second ADC (34) of the redundant monitoring channel (30) are designed to use the same reference voltage provided by a reference voltage source for each analog-to-digital conversion, - the signal for which analog-to-digital conversion is performed by the second ADC (34) includes a differential signal representing the difference between the supply voltage or reference voltage of the second ADC (34) and the provided first measurement signal, and the second output signal (U_AUX) represents a level-changed cell voltage signal, - the step of determining the comparison signal based on the first output signal (U_MAIN) and the second output signal (U_AUX) comprises: -- adding the first output signal (U_MAIN) and the second output signal (U_AUX); -- subtracting a set value of the supply voltage of the second ADC (34) when the level change of the cell voltage signal is caused by the supply voltage; and -- when the level change of the cell voltage signal is to the reference voltage A circuit device (10) comprising the step of subtracting the reference voltage when it occurs. Claim 10 A monitoring system for a rechargeable battery cell, wherein the monitoring system comprises a circuit device (10) of claim 6 or 7 and a control unit, wherein the control unit is designed to take a digital cell voltage signal (UC) provided by the circuit device (10) and representing the current cell voltage of the rechargeable battery cell as a basis for providing a next trigger threshold to the comparison unit (40), wherein the next trigger threshold is the first trigger threshold (TH1) when the digital cell voltage signal (UC) is less than the specified first voltage value and exceeds the second voltage value, the second trigger threshold (TH2) when the digital cell voltage signal (UC) is greater than or equal to the specified first voltage value, and the second trigger threshold (TH2) when the digital cell voltage signal (UC) is less than or equal to the specified second voltage value. Claim 11 A rechargeable battery system comprising: a rechargeable battery including at least one rechargeable battery cell; a circuit device (10) of claim 6 or 7 for each of all or at least some of the rechargeable battery cells; and a control unit, wherein the control unit is designed to take a digital cell voltage signal (UC) provided by each of the circuit devices (10) and representing the current cell voltage of each of the rechargeable battery cells as a basis for specifying a next trigger threshold to a comparison unit (40) of each of the circuit devices (10), wherein the next trigger threshold is: -- a first trigger threshold (TH1) when the digital cell voltage signal (UC) is less than the specified first voltage value and exceeds the second voltage value; -- a second trigger threshold (TH2) when the digital cell voltage signal (UC) is greater than or equal to the specified first voltage value; and -- a second trigger threshold (TH2) when the digital cell voltage signal (UC) is less than or equal to the specified second voltage value. Claim 12 A vehicle comprising the rechargeable battery system of claim 11.

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