Method for determining the respective temperature of a plurality of cell batteries of a vehicle battery by extrapolation from a measured temperature, control device and vehicle battery

Abstract

The invention relates to a method for monitoring the temperature of individual cells (2) of a vehicle battery (1) in an improved manner, having the following steps: determining (S1) measurement values comprising a first voltage of at least one first cell (11), a second voltage of at least one second cell (12) and at least one respective current flowing through the cells (11, 12); determining (S2) a first measured resistance of the first cell (11) and a second measured resistance of the second cell (12) from the measurement values; determining (S4) a reference resistance; determining (S5) a first resistance ratio between the first measured resistance and the reference resistance and a second resistance ratio between the second measured resistance and the reference resistance; determining (S6) a measured temperature of the first cell (11); and determining (S7) a calculated temperature of the second cell (12) from the measured temperature and the first and second resistance ratios in accordance with a predetermined specification.

Description

[0001] This invention relates to a method for determining the temperature of each of multiple cell units in a vehicle battery. A second aspect of the invention relates to a corresponding control device. A third aspect of the invention relates to a vehicle battery, particularly having said control device.

[0002] For the successful commercialization of electrically powered motor vehicles, they must meet high expectations and stringent requirements that have been satisfied by conventional fuel-powered motor vehicles in terms of lifespan, power capacity, range, and safety. Examples of electrically powered motor vehicles include pure electric vehicles with only an electric storage device and one or more electric motors, hybrid vehicles with an internal combustion engine, an electric storage device, and one or more electric motors, and hydrogen-powered vehicles, for example, with a fuel cell, an electric storage device, and one or more electric motors. The electric storage device of a motor vehicle can also be referred to as a vehicle battery and / or traction battery. A vehicle battery consists of multiple cell units connected in series and / or in parallel. These cell units are designed to collectively store electrical energy or collectively provide power. The cell units of a vehicle battery may all be connected in series. However, it is advantageously specified that multiple cell units are connected in series to form a group, wherein multiple such groups are connected in parallel. The nominal voltage level of the vehicle battery is obtained by the nominal voltage of these individual cell units and the number of cell units connected in series. Preferably, the nominal voltage level is at least 80 volts, more preferably at least 200 volts, for example 400 volts or 800 volts.

[0003] To ensure the efficient and safe operation of motor vehicles or vehicle batteries equipped with vehicle batteries, it is specifically stipulated that vehicle batteries be continuously monitored. This monitoring includes checking, for example, their individual temperature, voltage, current, state of charge (SoC), and / or depreciation rate or degradation (SoH). The listed parameters can be combined arbitrarily. Most advantageously, the temperature of each individual cell is continuously checked, determined, and monitored during operation. This is similarly applied to the depreciation rate or degradation (SoH).

[0004] Placing individual temperature sensors on each cell is extremely complex and costly. Therefore, the relationship between the aforementioned parameters and the internal resistance of each cell is typically utilized. In particular, the temperature and / or degradation of each cell can be inferred from its internal resistance.

[0005] For example, the internal resistance of each individual cell can be considered using a current pulse measurement method that fully utilizes the voltage response relationship to current pulses. This requires low computational cost, but can only provide such definite values ​​in an unordered manner. An alternative approach utilizes adaptive models, such as the so-called switching circuit model (circuit model ECM). This is especially based on Kalman filters.

[0006] The objective of this invention is to achieve improved temperature monitoring of individual cell units in a vehicle battery.

[0007] According to the invention, this task is accomplished through the subject matter of the independent claim. Advantageous embodiments with suitable improvements are the subject matter of the dependent claim.

[0008] A first aspect of the present invention relates to a method for determining the respective temperatures of multiple cell units in a vehicle battery. To allow for better monitoring of the respective temperatures, the method includes the following steps:

[0009] - Determine the measured values, which include a first voltage of at least one first cell and a second voltage of at least one second cell, as well as at least one respective current flowing through the cell;

[0010] - Determine the first measured resistance of the first cell and the second measured resistance of the second cell from the measured value;

[0011] - Determine the reference resistor;

[0012] - Determine the first resistance ratio between the first measuring resistor and the reference resistor, and the second resistance ratio between the second measuring resistor and the reference resistor;

[0013] - Determine the measurement temperature of the first cell unit;

[0014] - The calculated temperature of the second cell is determined according to the predetermined specifications based on the measured temperature and the first resistance ratio and the second resistance ratio.

[0015] In particular, the measured values ​​are determined by means of corresponding measurements using a measuring device. The measuring device is particularly designed to measure a first voltage and / or a second voltage and / or a respective current. Specifically, the respective currents flowing through the first and second cell units are the same because the two cell units are connected in series. The first and second measuring resistances can be determined based on the measured values. The determination of the first and second measuring resistances is particularly based on the mathematical relationship between current, voltage, and resistance. For example, the first measuring resistance of the first cell unit and the second measuring resistance of the second cell unit are determined from the measured values ​​using Ohm's law. In another design, more complex mathematical relationships, as will also be shown below in this application, can be employed.

[0016] The reference resistance can be, for example, a predetermined value. In this case, the reference resistance can be determined by retrieving the predetermined value from memory. Alternatively, the reference resistance can be formed as the average of all measured resistances of multiple cell units, such as a first measured resistance and a second measured resistance. In particular, the reference resistance is determined by averaging or forming an average value of all measured resistances of all cell units of the vehicle battery. The ratio of the first and second measured resistances can be formed by dividing each measured resistance, i.e., the first or second measured resistance, by the reference resistance. Alternatively, the first or second resistance ratio can be formed by dividing the reference resistance by the first or second measured resistance.

[0017] The temperature of the first cell can be determined by measuring its temperature. Specifically, the temperature is determined or measured using a temperature sensor. This temperature sensor can be, for example, an NTC sensor or a PTC sensor, or include such sensors. Alternatively, measurement can be performed using an infrared thermometer. Any other measurement method for the temperature of the first cell is also conceivable. Generally, the temperature of the first cell can be determined using a temperature sensing unit.

[0018] The calculated temperature is determined based on the first resistance ratio and the second resistance ratio, and the measured temperature is performed according to predetermined rules. The calculated temperature here indicates the temperature of the second cell, while the measured temperature indicates the measured temperature of the first cell. It is so named "calculated temperature" because it is not measured, but rather derived or determined from given parameters using predetermined rules.

[0019] This invention is based on the concept of extrapolating the temperature of a second cell from the temperature of a first cell. For extrapolation, the measured temperature is correlated with the first and second resistance ratios. Here, the invention utilizes the understanding that the internal resistance of each cell decreases as the temperature of the respective cell increases. Therefore, based on the respective internal resistances of the first and second cells, i.e., the first and second measured resistances, the temperature of the first cell can be extrapolated to the second cell. It is particularly important to consider that there is no linear relationship between the temperature and the respective internal resistance. The relationship between the respective internal resistance and temperature can be used, for example, by a distribution function and / or a corresponding value table. This relationship, especially the distribution function or value table, can be predetermined. In particular, the relationship, especially the distribution function or value table, is derived through corresponding experiments for such vehicle batteries or respective cell units. The numerical generation of the value table or distribution function can be specified here. In summary, this demonstrates how improved monitoring of the temperature of each cell in a vehicle battery can be achieved. In particular, only a small number of temperature measuring units or temperature sensors may be sufficient to determine the respective temperatures of all cell units using the method of this invention. This reduces the complexity of vehicle battery construction on the one hand, and saves costs on the other.

[0020] This method can generally be implemented without the need to determine a reference resistor and the ratio of the first and second resistances. In this case, the temperature calculation can be performed differently based on the measured temperature and the first and second measured resistances according to predetermined specifications. However, it has been shown that setting a ratio for the reference resistor (also known as normalization) provides more reliable results. This is particularly based on the understanding that absolute resistance is not important, because the individual cell with the lowest internal resistance is usually the hottest cell, and the cell with the highest internal resistance is usually the coldest cell. Since the determination of the calculated temperature is also based on the measured temperature, it is sufficient to consider the measured resistance normalized to the reference resistor, i.e., the first or second resistance ratio. Normalization provides a more consistent data basis.

[0021] According to an improved embodiment, the predetermined specification includes an allocation function and / or value table, which assigns a plurality of values ​​for a second resistance ratio to the temperature, i.e., the calculated temperature, based on the measured temperature and a first resistance ratio, particularly a corresponding value. It can be specified that the allocation function and / or value table are generated through corresponding tests or measurements on the vehicle battery. The value table or allocation function can be provided by mathematical relations or formulas or numerical values. Furthermore, the value table and / or allocation function can have the state of discharge of the vehicle battery and / or its respective cell as parameters. In other words, a correspondingly applicable allocation function and / or value table can be considered for different values ​​of the state of charge of the vehicle battery and / or its respective cell. In this case, the method may include, as an additional step, "determination of the state of charge of the vehicle battery and / or its respective cell." In this way, a more accurate determination of the temperature of the second cell, particularly the calculated temperature, can be obtained.

[0022] According to an improved scheme, a normalized allocation function and / or value table is first established based on a first resistivity ratio and a measured temperature. Then, the calculated temperature is derived from the normalized allocation function and / or value table based on a second resistivity ratio. In other words, the allocation function and / or value table is first selected or generated based on the data of the first cell, i.e., the first resistivity ratio and the measured temperature. Then, the calculated temperature is selected from the allocation function and / or value table generated in this way based on the second resistivity ratio. Here, the normalized allocation function and / or value table can show a one-to-one relationship between the calculated temperature and the second resistivity ratio. In this way, the calculated temperature can be easily derived from the normalized allocation function and / or value table. The generation or selection of the normalization or normalized allocation function and / or value table can also be based on predetermined data.

[0023] According to an improved scheme, a second resistance ratio for each of the multiple second cell units is determined, and thereby, based on predetermined specifications, a measured temperature, and a first resistance ratio, a calculated temperature for each of the second cell units is determined. In other words, the calculated temperature of the second cell unit is determined in parallel for the multiple second cell units in a similar manner. Here, for each second cell unit, a second resistance ratio can be derived from a measured resistance determined for that second cell unit. To determine the respective second measured resistance, a second voltage for each second cell unit can be determined. A current for each second cell unit can be determined, wherein the respective current can be the same for all second cell units in the case of series connection. The calculated temperature of each second cell unit is then determined based on the first resistance ratio and the measured temperature of the first cell unit. In other words, the calculated temperature of each second cell unit is extrapolated based on the measured temperature of the first cell unit and its resistance or resistance ratio. This method eliminates the need for multiple temperature sensors, as a temperature sensor is no longer required for each individual second cell unit.

[0024] According to an improved scheme, the respective measured temperatures and respective first resistivity ratios of multiple first cell units are determined, and the respective calculated temperatures of the second cell units are determined based on predetermined specifications and second resistivity ratios. In other words, the calculated temperature of the second cell unit is extrapolated based on the respective measured temperatures and respective first resistivity ratios of the multiple first cell units. In particular, the determination or extrapolation of the calculated temperatures is performed independently of each individual cell unit. Multiple calculated temperatures of the second cell unit are obtained in this way. In other designs, it can be specified that the multiple calculated temperatures of the second cell unit are averaged. Before averaging, outliers, i.e., calculated temperatures of the second cell unit that differ from the remaining values ​​by a predetermined amount, can be filtered out. This is because such drastically different values ​​or outliers are likely caused by measurement errors or errors in the determination of the calculated temperatures. In this way, the accuracy of determining the individual temperatures of the cell units can be further improved.

[0025] According to an improved embodiment, at least one measured temperature of one of a plurality of first cell units located at the edge of the vehicle battery and at least one measured temperature of one of a plurality of first cell units centrally located within the vehicle battery are determined. In other words, respective temperature sensors or respective temperature measuring units are mounted on at least one first cell unit located at the edge of the vehicle battery, and at least one temperature sensor or temperature measuring unit is mounted on a first cell unit centrally located within the vehicle battery. For example, a first cell unit located at the edge of the vehicle battery may be adjacent to only one other cell unit. For example, a first cell unit centrally located within the vehicle battery may be adjacent to each of two other cell units on multiple sides. In this way, different temperature measurements are obtained for different installation configurations of different first cell units. This allows for more accurate determination of the measured temperatures and, consequently, the derived calculated temperatures or multiple calculated temperatures.

[0026] According to an improved scheme, it is specified that a reference state exists, in which the correlation coefficient G is greater than a predetermined value and / or the individual measured temperatures of the multiple first cell units are not higher than a predetermined level. The correlation coefficient G specifically indicates the regression quality of the determination of the individual measured resistances. Here, the correlation coefficient G is particularly a quality coefficient, which characterizes the data quality of the measured values ​​or the resistance values ​​derived therefrom. Here, the reference state is particularly applicable to a static state, in which the vehicle battery is in a static state. In the reference state, or precisely when a reference state exists, the determination of the individual temperatures of the multiple cell units can be abandoned, because it can be assumed that they develop constantly over time. In addition, other evaluations can be completed precisely when a reference state exists. In particular, the degradation or degradation change of the vehicle battery is quantified by comparing it with an earlier reference state. This is based on the understanding that the gradual change characteristics or long-term characteristics of the measured values ​​do not originate from changes in the cell unit temperature, but from changes in their degradation. Therefore, the changes in the state of the vehicle battery or individual cell units or their degradation can be inferred from the long-term characteristics.

[0027] A second aspect of the invention relates to a control device for determining the respective temperatures of multiple cell units in a vehicle battery, wherein the control device is designed to:

[0028] - Receive measurement values, including a first voltage of at least one first cell and a second voltage of at least one second cell, as well as at least one respective current flowing through each cell.

[0029] -From this measurement value, determine the first measured resistance of the first cell and the second measured resistance of the second cell.

[0030] - Determine the reference resistor,

[0031] - Determine the first resistance ratio between the first measuring resistor and the reference resistor, and the second resistance ratio between the second measuring resistor and the reference resistor.

[0032] - Receive the measured temperature of the first cell, and

[0033] - The calculated temperature of the second cell is determined according to the predetermined specifications based on the measured temperature and the first resistance ratio and the second resistance ratio.

[0034] In particular, the control device is designed to execute the method of the present invention according to one or more of the embodiments described herein. For example, the control device includes a computing unit, which is designed, for example, a microcontroller, a field-programmable gate array (FPGA), or a digital signal processor (DSP). The control device or computing unit may have memory units such as flash memory, magnetic memory media, and / or optical memory media, wherein the stored computer program product contains program code structures for executing the method of the present invention or the various method steps of the method of the present invention. In particular, the program code structures, when running on the control device or computing device, allow execution of the method of the present invention according to one or more embodiments.

[0035] A third aspect of the present invention relates to a vehicle battery having:

[0036] -The aforementioned control device.

[0037] - At least one first cell and a respective temperature measuring unit for determining the respective measured temperature of each first cell.

[0038] -At least one second cell battery, and

[0039] - A measuring device for determining a measured value, which includes a first voltage of a first cell and a second voltage of a second cell, and at least one respective current flowing through the cell.

[0040] For example, a vehicle battery can be designed as a lithium-ion battery. The vehicle battery can have a voltage level greater than 80 volts, preferably greater than 200 volts, such as 400 volts or 800 volts. In particular, the vehicle battery has multiple temperature sensing units, such as two, three, or four. In this case, four cells of the vehicle battery are suitable as the first cell in the sense of this application. The respective temperatures of the remaining cells of the vehicle battery, which may also be referred to as the second cell in the sense of this application, are extrapolated based on the respective measured temperatures of the one or more first cells.

[0041] Other advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and in conjunction with the figures. The features and combinations of features mentioned above in the specification, as well as the features and combinations of features mentioned below in the description of the drawings and / or shown individually in the figures, may be used not only in their respective specified combinations, but also in other combinations or individually, without departing from the scope of the invention, wherein:

[0042] Figure 1 A schematic block diagram of a vehicle battery with multiple cell units is shown, wherein several cell units have their own temperature sensors, and the temperatures of the remaining cell units are extrapolated based on the measured temperatures of these cell units and their respective resistances.

[0043] Figure 2 An exemplary method process is illustrated in the process diagram;

[0044] Figure 3 An exemplary assignment function determined by experiment is shown.

[0045] Figure 1 A vehicle battery 1 having multiple cell units 2 is shown according to a highly exemplary embodiment. The cell units 2 are divided into two groups 3, wherein the cell units 2 of each group 3 are connected in series. The groups 3 are also connected in parallel. Obviously, any other meaningful connection of the cell units 2 is also feasible. In particular, the vehicle battery 1 is designed as a so-called traction battery for supplying electrical energy to the electric drive system of a motor vehicle to drive or accelerate the vehicle. The vehicle battery 1 or its cell units 2 are particularly based on lithium-ion battery technology.

[0046] Vehicle battery 1 has an electrical connector 5 to which the output voltage of vehicle battery 1 is applied. Specifically, loads, particularly converters for operating the motor of the vehicle and / or transformers for supplying power to the vehicle's onboard power supply, are connected to electrical connector 5. In other words, vehicle battery 1 can output electrical energy or power through electrical connector 5. Electrical connector 5, which may be the only source of power, extends from the battery casing 6 of vehicle battery 1. Electrical connector 5 can provide power through two terminals. The nominal output voltage of vehicle battery 1 is particularly greater than 80 volts, preferably greater than 200V, for example, 400 volts or 800 volts. When using lithium-ion based cell batteries 2, the number of cell batteries 2 connected in series is also derived from the desired nominal voltage level of the output voltage.

[0047] To ensure a high level of safety during the operation of the vehicle battery 1 and to extend its lifespan as much as possible, it is necessary to monitor the vehicle battery 1 extensively. Monitoring may include, for example, output voltage, current flow, temperature, state of charge (SOC), and degradation (SOH). Particularly preferred is that the monitoring is performed not only on the entire vehicle battery 1 but also at least partially on each individual cell 2. This allows for the identification of damage to individual cell 2 or the prevention of such damage.

[0048] The vehicle battery 1 has multiple temperature measuring units 4. Each temperature measuring unit 4 is associated with a specific cell 2. Here, the temperature measuring unit 4 is designed to measure the temperature of its respective cell 2. The cell 2 associated with the temperature measuring unit 4 is also referred to as the first cell 11. Obviously, only a small portion of the cell 2 is associated with the temperature measuring unit 4. Cell 2 not associated with the temperature measuring unit 4 is also referred to as the second cell 12. Only a small number of temperature measuring units 4 are provided to keep the vehicle battery 1 as low as possible in terms of complexity and manufacturing cost. On the other hand, it is desirable to determine the individual temperature of all cell 2. Therefore, the measured temperature of the first cell 11 is extrapolated to the second cell using a method for determining the individual temperatures of the cell 2 in the vehicle battery 1. To perform this method, the vehicle battery 1 may have a corresponding control device 9.

[0049] Here, the vehicle battery 1 has a measuring device 7 designed to measure or determine the current and voltage of individual cell 2. Specifically, it can be specified that the voltage of each cell 2 is measured or determined. It can also be specified that the current of each cell 2 is measured independently of each other. However, it is preferred that the current is measured or determined jointly for multiple cell 2. Because multiple cell 2 are connected in series, the individual currents flowing through the series-connected cell 2, in this case, a group of 3, are each the same. In this way, the current can be measured only once for each group 3. Alternatively, the total current of all groups 3 can be measured and divided by the number of groups 3, especially under the assumption that the total current is evenly distributed among all groups 3. According to another alternative, the current of one group 3 can be measured, and it is assumed that the current of another group 3 is equal to it. Regarding the... Figure 2 The process diagram shows that the measurement of the given measured value corresponds to step S1. Alternatively or additionally, the measured value is received by the control device 9 in step S1.

[0050] Based on the measured values, namely the respective values ​​for current and voltage, the individual resistance, also known as the measured resistance, for each cell 2 can be determined. This can be done, for example, based on Ohm's law. In other embodiments, this is done according to different formula algorithms, which will be explained in detail below. The determination of the individual resistance or internal resistance of each cell 2 corresponds to step S2.

[0051] In step S3, it is determined whether a reference state or a so-called "stable state" exists. In the reference state, in this embodiment, the temperatures of the first cell 11 differ from each other by a predetermined amount at most. Additionally, in this embodiment, the correlation coefficient G is greater than a predetermined value in the reference state. The correlation coefficient G will be described in detail below, also in formula (22). If such a reference state exists, the method for determining the respective temperatures is interrupted until it is performed in another manner. In this case, the temperature of the second cell 12 is not determined, which corresponds to path "n" in the process diagram; instead, the degradation ("health state") of the battery is determined. Figure 2 The middle corresponds to the path "y".

[0052] In another step S6, the temperature value from the temperature measuring unit 4 is retrieved or received. This is done, in particular, by the control device 9. Alternatively or additionally, the temperature value measurement by means of the temperature measuring unit 4 can also be performed in step S6. Step S6 can be repeated and / or performed before step S3, so the temperature value for step S3 is always provided in real time.

[0053] If no reference resistor is available, the method can proceed to step S4. In step S4, a reference resistor is determined. This reference resistor can be, for example, a predetermined value, retrieved from the storage unit of the control device 9 during step S4. In this embodiment, the reference resistor is determined from the internal resistance or measured resistance of all cell batteries 2. In particular, the reference resistor is determined by averaging the internal resistance or measured resistance. In other words, the reference resistor can be an average value with respect to the internal resistance or measured resistance.

[0054] In step S5, the respective resistance ratios of the respective internal resistances of the cell 2 are determined. The respective resistance ratios are calculated by dividing the respective internal resistance or measured resistance by a reference resistance. Alternatively, the respective resistance ratios can be calculated by dividing the reference resistance by the respective internal resistance or measured resistance.

[0055] In method step S7, a true extrapolation of the measured temperature or temperature value of the first cell 2 is performed. In this case, the calculated temperatures of all second cells 12 are determined based on their respective resistance ratios according to the measured temperatures. The calculated temperatures may be based on predetermined rules. In particular, the predetermined rules correlate the respective temperatures of the cells 2 with their respective resistance ratios. Here, the predetermined rules may include value tables and / or allocation functions 15. In particular, the value tables and / or allocation functions 15 can be derived from corresponding laboratory tests. The results of the corresponding laboratory tests may be included in the value tables and / or allocation functions in numerical form or presented through mathematical functions.

[0056] Figure 3 An exemplary allocation function 15 is shown, which describes the respective resistance ratio V of the corresponding second cell 12. R2The State of Charge (SOC) indicates the temperature T of each of the second cell 12. R The exemplary allocation function 15 is generated here based on the first resistance ratio and the measured temperature of each of the first cell 11 as parameters. In other words, the allocation function 15 is generated based on the measured temperature and the first resistance ratio of each of the first cell 11, so that the allocation function is based on its resistance ratio V. R2 The temperature T of the second cell 12 is derived from the state of charge (SOC). R In another design, this can be performed independently of each other based on the corresponding first cell 11 for the corresponding second cell 12. In this way, the same number of calculated temperatures are obtained for each cell 12 as for the number of existing first cell 11s or temperature sensing units 4. Multiple calculated temperatures for each cell 12 can be averaged. In another design, outliers or significantly different values ​​can be picked out before averaging. In this way, very accurate determination of the calculated temperature is achieved.

[0057] The mathematical principles of this invention will now be described in more detail:

[0058] A. Algorithm for determining resistance

[0059] The basis for determining or calculating the internal resistance of each component is to divide the curves of the measured parameters (current and voltage) into instantaneous system responses I(t)·R. Ohm (t) and delayed system response

[0060]

[0061] Instantaneous system response via ohmic resistor R Ohm The voltage across I(t) is described based on the current I(t). Delayed system response. It is further divided into deterministic parts. and random noise component

[0062]

[0063] The deterministic characteristics of delayed cell batteries can be expressed using a switching circuit model (ECM) with two resistance pairs.

[0064]

[0065]

[0066]

[0067]

[0068] Random noise can be expressed using the method of independent Gaussian noise with a mean of 0.

[0069]

[0070] ECM parameter R Ohm R Pol R Diff C Pol C Diff and C N The values ​​of vary over time depending on operating conditions and cell state. The requirement for using a random method necessitates discretizing this voltage and current signal, which is in the form of sampled values. The sampling parameter n and sampling rate T... S Two requirements should be met. Firstly, the sampling range n should be large enough to satisfy a high-confidence random measure. Secondly, the ohmic resistance R... Ohm (t) and the deterministic system characteristics should remain constant Δt = nT during the sampling time interval. S .

[0071] Based on the aforementioned requirements, the total difference in ohmic resistance

[0072]

[0073] It should be negligible in the sampling interval Δt. The total difference in the delayed system response leads to the following equation:

[0074]

[0075] The condition at this point is the change in OCV.

[0076]

[0077] Negligible over short intervals. This is due to the large time constant of the diffusion process.

[0078] T S <<R Diff ·C Diff (11)

[0079] It can also be used to pair the second RC

[0080]

[0081] Negligible. The total change in the first RC pair is based on a low time constant.

[0082] T S >R Pol ·C Pol (13)

[0083] Within a wide temperature and SoC (State of Charge) range

[0084]

[0085] The variation in random measurement noise is not negligible. The total difference in the delayed system response leads to...

[0086]

[0087] The result is obtained by using the inverse difference of the discrete voltage signal:

[0088]

[0089] For a better overview, the discrete signals are combined in the following vector.

[0090]

[0091] The length of the sample parameter n specifically corresponds to the number of cell units 2. The system equations can now be written in vector notation:

[0092]

[0093] One possible way to determine the ohmic resistance is therefore to apply the voltage vector covariance to the current vector.

[0094]

[0095] The condition is that the current current vector is constant and the variance of the current current vector is zero. The second term of Equation 19 can be approximated by Equations (9)-(15):

[0096]

[0097] Therefore, the covariance of the cell voltage and current can be approximated as follows:

[0098]

[0099] This is defined as the internal resistance R of each individual cell 2. I (t). Applying regression methods to real data requires filtering techniques because the real change curve includes many stages in which the current is constant or zero. In the case of using the least square root method, the correlation coefficient is used to evaluate the quality of the regression.

[0100]

[0101] The quality coefficient G is added to the database for each sample to evaluate the estimate. This application includes two different regression methodologies. One method requires backups of the data for each sample to analyze and calculate the covariance and correlation coefficient. The other algorithm approximates the covariance and correlation coefficient without requiring temporary storage. Both algorithms are described in full below, including the filters used, initial values, and definitions.

[0102] B. Overview of Regression Methods (RM) with Data Backup

[0103] Symbols and definitions:

[0104] Sample vector

[0105] For current

[0106] For voltage

[0107] Accompanying optimized sampling parameters

[0108] Initialization: k = 0

[0109]

[0110] Calculation, for k>0

[0111]

[0112]

[0113]

[0114]

[0115] C. Overview of Recursive Methods (RRM) definition:

[0116]

[0117] Initialization: k = 0

[0118]

[0119]

[0120]

[0121] Initial state calculation: 0≤k <n opt

[0122]

[0123]

[0124] For k≥n opt Calculation:

[0125]

[0126]

[0127]

[0128]

[0129]

[0130]

[0131] D. Degradation (SoH) and Temperature Estimation

[0132] The output of the database-based algorithm results in the resistance distribution of the lithium-ion battery within vehicle battery 1. The allocation consists of degradation (SoH) and temperature gradient, as well as errors during cell manufacturing and module design. To distinguish the causes, a reference allocation will be used.

[0133]

[0134] Placed in a no-load state. The exponent j represents the respective period. Brief changes in the reference allocation.

[0135]

[0136] This can be attributed to the temperature gradient within the battery. Long-term drift between the following reference settings.

[0137]

[0138] Describe the aging rate gradient, which affects degradation or SoH.

[0139] List of reference numerals

[0140] 1. Vehicle battery

[0141] 2-cell battery

[0142] 3 groups

[0143] 4 Temperature Measurement Unit

[0144] 5 connectors

[0145] 6. Battery casing

[0146] 7. Measuring device

[0147] 9. Control device

[0148] 11 First Unit Battery

[0149] 12 Second Unit Battery

[0150] 15. Assignment function.

Claims

1. A method for determining the temperature of each of a plurality of cell units in a vehicle battery (1), comprising the following steps: - Determine (S1) the measured values, which include a first voltage of at least one first cell (11) and a second voltage of at least one second cell (12), as well as at least one corresponding current flowing through the first cell (11) and the second cell (12). - Determine (S2) the first measured resistance of the first cell (11) and the second measured resistance of the second cell (12) from the measured values. - Determine the (S4) reference resistor, - Determine (S5) the first resistance ratio between the first measuring resistor and the reference resistor, and the second resistance ratio between the second measuring resistor and the reference resistor. - Determine (S6) the measured temperature of the first cell (11), and - The calculated temperature of the second cell (12) is determined (S7) according to a predetermined specification based on the measured temperature, the first resistance ratio, and the second resistance ratio. The predetermined specification includes an allocation function (19) and / or a value table, which assigns a corresponding value for the temperature to a plurality of values ​​for the second resistance ratio based on the measured temperature and the first resistance ratio.

2. The method according to claim 1, characterized in that, The reference resistor is formed as the average of all measured resistances for the plurality of cell units.

3. The method according to claim 1 or 2, characterized in that, Based on the first resistance ratio and the measured temperature, the allocation function and / or value table is first normalized, and then the calculated temperature is derived from the normalized allocation function and / or value table based on the second resistance ratio.

4. The method according to claim 1 or 2, characterized in that, The respective second resistance ratios for the multiple second cell units (12) are determined, and the corresponding values ​​of the calculated temperatures for the respective second cell units (12) are determined based on the predetermined provisions, the measured temperature, and the first resistance ratio.

5. The method according to claim 1 or 2, characterized in that, The respective measured temperatures and respective first resistivity ratios for the plurality of first cell units (11) are determined, and the corresponding values ​​for the calculated temperature for the second cell unit (12) are determined based on the predetermined provisions and the second resistivity ratio.

6. The method according to claim 5, characterized in that, The measured temperature of at least one of the first cell batteries (11) located at the edge of the vehicle battery (1) and the measured temperature of at least one of the first cell batteries (11) located centrally within the vehicle battery are determined.

7. The method according to claim 1 or 2, characterized in that, Check (S3) whether there is a reference state, wherein the correlation coefficient G is greater than a predetermined value, and / or the individual measured temperatures of the multiple first cell batteries are not higher than a predetermined level relative to each other.

8. The method according to claim 2, characterized in that, The reference resistor is formed as the average of the first measuring resistor and the second measuring resistor.

9. A control device (9) for determining the temperature of each of a plurality of cell units in a vehicle battery (1), wherein, This control device is designed for: - Receive measurement values, said measurement values ​​including a first voltage of at least one first cell (11) and a second voltage of at least one second cell (12) and at least one corresponding current flowing through the first cell and the second cell. - Determine the first measured resistance of the first cell (11) and the second measured resistance of the second cell (12) from the measured values. - Determine the reference resistor, - Determine a first resistance ratio between the first measuring resistor and the reference resistor, and a second resistance ratio between the second measuring resistor and the reference resistor. - Receive the measured temperature of the first cell (11), and - The calculated temperature of the second cell (12) is determined according to a predetermined specification based on the measured temperature and the first resistance ratio and the second resistance ratio. The predetermined specification includes an allocation function (19) and / or a value table, which assigns a corresponding value for the temperature to a plurality of values ​​for the second resistance ratio based on the measured temperature and the first resistance ratio.

10. A vehicle battery (1) comprising: - The control device (9) according to claim 9, - At least one first cell (11) and a corresponding temperature measuring unit for determining the respective measured temperature of each first cell (11), -At least one second cell (12), and - A measuring device for determining a measured value, the measured value including a first voltage of a first cell (11) and a second voltage of a second cell (12) and at least one corresponding current flowing through the first cell (11) and the second cell (12).

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