Method for operating a battery system and battery system

Abstract

The present invention relates to a method for operating a battery system and a battery system comprising a battery cell stack having a plurality of individual cells, a temperature control device for each individual cell, and at least one temperature sensor, the temperature control device being located on a first end face of the battery cell stack, and the at least one temperature sensor being disposed in a region of the battery cell stack opposite to the first end face. The method comprises the steps of: a) checking whether a temperature signal generated by the temperature sensor represents a temperature less than a predetermined temperature threshold; b) if the represented temperature is less than the temperature threshold, performing load power regulation independent of the temperature signal.

Description

Technical Field

[0001] This invention relates to a method for operating a battery system and a battery system. Background Technology

[0002] Battery systems are used in vehicles, particularly electric and hybrid vehicles, to store the energy needed to drive the vehicle in the form of electrical energy. For example, the electric traction motor of a vehicle can operate using energy obtained from a battery system.

[0003] Motorized vehicles that are driven or propelled by electric or motor-driven systems, such as electric or hybrid vehicles, typically include an electric motor that can drive one or two axles. To supply electrical power, the electric motor is usually connected to an internal (high-voltage) battery as an energy storage device.

[0004] To provide sufficient energy for the vehicle's expected operating time, individual battery cells of the battery system can be charged.

[0005] Here and below, the term "load process" (Ladevorgang) should be understood in particular as referring to the charging of a battery system or individual battery cells by means of load current (charging current, discharging current), but it can also be understood as discharging. During charging, electrical energy is supplied to individual battery cells through the (charging) current, while during discharging, electrical energy is dissipated from individual battery cells through the (discharging) charging current.

[0006] In this context and below, "electrochemical battery" should be understood, in particular, as a so-called secondary battery (rechargeable battery) for motor vehicles. Using such a vehicle battery, the used chemical energy can be recovered through an electrical (charging) load process. This type of vehicle battery is designed, for example, as an electrochemical rechargeable battery, particularly a lithium-ion rechargeable battery.

[0007] To generate or provide a sufficiently high operating voltage, such vehicle batteries typically have at least one single-cell module, in which multiple individual electrochemical single cells are modularly connected. Alternatively, a so-called single-cell to battery pack (C2P) design is possible, in which single cells are directly interconnected into the vehicle battery, particularly in parallel connection, and are not pre-assembled into modules.

[0008] Depending on the cell temperature, duration of charging, and state of charge, a single cell, especially a lithium-ion cell, can only absorb a certain amount of charging current without being damaged. This limiting current varies with the aging state of the cell. Furthermore, there is the challenge of connecting multiple cells with different temperatures and / or aging states in series or parallel within a battery system.

[0009] Therefore, it is necessary to know the charging and aging states of all individual cells in the battery system, as well as the coldest and hottest points, at all times. It is also necessary to know the temperature gradient within each individual cell to understand the coldest and hottest points of the entire battery system. These two points, along with the charging and aging states of each individual cell, determine the maximum possible charging current at any given time. Since a relaxed individual cell can absorb a current higher than the maximum possible continuous current for a short period, it is also essential to know the cell's temporal response to the charging current. "Relaxation" or "slack" should be understood specifically as the steady-state state of the individual cell achieved after the charging or discharging current has ended.

[0010] What I still hope for is

[0011] • The state of charge distribution within the battery system should be as equal as possible.

[0012] • Individual battery cells will not be overcharged (e.g., final charging voltages of 3.7 V, 4.2 V, 4.3 V, 4.5 V).

[0013] • The state of charge is known, especially for range or runtime predictions.

[0014] • The voltage of a single battery cell shall not be lower than a predetermined voltage (e.g., 2V, 2.5V, 3V).

[0015] • A single battery cell will not be deeply discharged.

[0016] Especially during current-controlled charging, it is crucial to accurately determine the temperatures of the hottest and coldest points in the battery system to charge it with the correct power without damaging the battery. Exceeding the maximum temperature can lead to accelerated battery aging or irreversible damage, and in the worst case, trigger an exothermic reaction. Therefore, understanding the temperature of the battery's hottest points is essential for high-level operational reliability. Power throttling can be applied when certain temperature levels are exceeded. This is also known as thermal derating.

[0017] Aging or damage processes in lithium-ion battery packs with liquid electrolytes include, for example, so-called lithium deposition (Li- deposition), in which metallic lithium is deposited on the surface of the anode and irreversibly reacts with the components of the electrolyte. As a result, for example, the capacity of a single cell is lost due to the reduction of free lithium ions. Furthermore, this can lead to electrical short circuits within the single cell, potentially causing the cell to catch fire during charging. Lithium plating occurs when the potential of the anode material and electrolyte is lower than the potential of lithium. During charging, overvoltage occurs, lowering the anode potential. This overvoltage is comprised of the separator / electrolyte section, the cathode section, and the anode section, with the anode section being the critical part for lithium plating. At high charging currents, the anode potential drops below the lithium potential (0 volts vs. Li / Li+), causing lithium ions to deposit on the anode surface.

[0018] In particular, to prevent this lithium deposition, it may be necessary to know the temperature of the coldest point in order to control the current release based on the coldest region of the active material inside the battery.

[0019] The temperature associated with current / power release is typically the temperature of the active materials within the individual cells of a battery. According to current technology, it is impossible to measure the temperature of the active materials using physical sensors within the battery. Temperature sensors (preferably designed as NTC, but also PTC, thermocouples, Pt100, Pt1000) are located near temperature peaks (cold or hot spots) on the outside of the battery. This alone results in a loss of crucial knowledge about the accurate temperature.

[0020] Therefore, tolerances must be planned and the corresponding safety margins must be subtracted from the current / power release.

[0021] In addition, temperature sensors are used in cooling and heating strategies within the battery, which is why accurate measurements are required throughout the operating temperature range.

[0022] When a single cell is unilaterally conditioned by means of a cooling plate (that is, heat is introduced into or extracted from the cell from only one side), a significant temperature difference is generated on the side of the cell closest to the cooling plate and the side furthest from the cooling plate by pre-conditioning (heating) or cooling the single cell. This further complicates temperature-related load power regulation.

[0023] Therefore, in the most extreme case, the optimal possible load power regulation requires two temperature sensors per battery cell: one for the hot spot and one for the cold spot. If redundancy is to be provided with at least two temperature sensors per hot and cold spot, for example, to detect defects in the temperature sensors, this results in four temperature sensors per battery cell. This, in turn, increases the workload required for the signal connections of these temperature sensors, such as through flexible...

[0024] Printed cables (FPCs) connect temperature sensors to sensor evaluation and battery control units (such as CMCs).

[0025] For lithium-ion batteries, the maximum possible charging current can be determined, for example, by adjusting the potential of the anode under load using a 3-electrode battery. This can only be achieved in a 3-electrode battery with a reference electrode. Then, in the battery system, the reduction in the load current characteristic curve is proportional to the reduction in capacity or the increase in internal resistance during the aging process of a single cell. For example, SIEG, Johannes et al., article: Fast charging of lithium-ion batteries for electric vehicles under the limits of lithium deposition process. See: Journal of Power Sources, Vol. 427, 2019, pp. 260-270 and DE 10 201 6 007 479 A1. However, the limitation of this method is that, for each single cell in the system, the minimum and maximum temperatures in the single cell must be known in order to select the maximum permissible load current from the characteristic curve. In addition, the aging state of each single cell in the battery system must be known, especially the current internal resistance, because in the process described there, the oldest single cell determines the current. Furthermore, for battery systems used as batteries in transportation vehicles, it is necessary to construct experimental laboratory single cells with reference electrodes from industrially manufactured battery single cells.

[0026] Furthermore, as is known from DE 10 201 9 003 465 A1, for example, a three-electrode cell can be used to determine the maximum pulse current for each load state of a relaxed cell. However, this method presents similar challenges to those described above. Additionally, a large number of characteristic maps must be determined and stored in the system.

[0027] Generally, if the system stores explicit load current characteristic plots, the highest and lowest temperatures in the system need to be accurately determined, and the large number of stored characteristic plots must be used without errors. Stable and safe operation must be ensured through complex programming and comprehensive testing.

[0028] Furthermore, for example, the harmfulness of the load current characteristic diagram, which depends on temperature, load state, and pulse duration, can be checked by repeatedly applying it to the battery, and the system can then be preset accordingly.

[0029] DE 20 202 1 203 390 B3 discloses a method for voltage-controlled operation of a battery system having at least one electrochemical cell during a charging process.

[0030] Therefore, the technical problem that arises is to create a method for operating a battery system and a battery system that can achieve the highest possible operational reliability during charging and discharging, while reducing manufacturing costs and installation space requirements.

[0031] The solution to this technical problem originates from the subject matter characterized by independent claims. Advantageous improvements and extensions are the subject matter of dependent claims. Summary of the Invention

[0032] A method for a battery system for operating vehicles is proposed, wherein the battery system has a battery single-cell stack with multiple battery single cells.

[0033] Each battery cell can be a cuboid or substantially cuboid and has a length, width, and height. Battery cells can also be designed as pouch cells or circular cells, for example, according to the 18650 or 21700 format describing the dimensions and design of the battery cells. A battery cell stack can be assigned a stack longitudinal axis, a stack transverse axis, and a stack vertical axis. Each battery cell can then extend along the stack longitudinal, transverse, and vertical directions. The dimension of a battery cell along the stack longitudinal axis can be a cell length, a cell width along the stack transverse axis, and a cell height along the stack vertical axis. Battery cells in a battery cell stack can be arranged one after another along the stack longitudinal direction. A battery cell stack can have two longitudinal axis-specific end faces along the stack longitudinal axis, which can be orthogonal to the stack longitudinal axis. These can correspond to the longitudinal axis-specific end faces of the first and last battery cells in the battery cell stack. Therefore, a battery cell stack can have two transverse axis-specific end faces along the stack transverse axis, which can be orthogonal to the stack transverse axis. These end faces can consist of cell-specific, lateral axis-specific end faces. Therefore, a cell stack can have two vertical axis-specific end faces along the stack's vertical axis, which can be orthogonally oriented to the stack's vertical axis. These end faces can consist of cell-specific, vertical axis-specific end faces.

[0034] The battery system also includes a device for temperature regulation of individual battery cells (temperature regulation device). This can be designed and arranged in such a way that heat is transferred from the individual battery cell stack to the temperature regulation device for cooling, and heat is transferred from the individual battery cell stack to the temperature regulation device for heating. It is possible that, using the temperature regulation device, the individual battery cell stack can be heated without cooling, cooled without heating, or both, or heated. The temperature regulation device is specifically designed as a cooling plate. The temperature regulation device is disposed on the first end face of the individual battery cell stack. This can also be referred to as the active thermal side. The temperature regulation device can be placed on this end face or spaced apart from it along the vertical axis of the stack by a predetermined dimension.

[0035] The battery system also includes at least one temperature sensor. It may include exactly one temperature sensor. Preferably, the number of temperature sensors is less than the number of individual battery cells. In particular, the number of temperature sensors may be less than half the number of individual battery cells.

[0036] At least one temperature sensor is arranged in a region of the battery cell stack facing away from the first surface. This can mean that the temperature sensor is at a greater distance from the first end face than the temperature sensor is at a greater distance from the end face of the battery cell stack opposite to the first end face, which may also be referred to as the thermal passive side. Specifically, the distance of each temperature sensor from the first end face can be greater than the distance from its opposite side. In particular, the ratio of the distance to the opposite side to the distance to the first end face can be less than 1, preferably less than 0.25.

[0037] Specifically, the temperature control device can be arranged on one of the two specific end faces of the vertical axis. Furthermore, at least one temperature sensor can be arranged in a region of the other specific end face of the vertical axis, for example, on the other specific end face of the vertical axis. However, this is not mandatory. At least one temperature sensor can also be arranged on one of the two specific end faces of the transverse axis or on one of the specific end faces of the longitudinal axis. The distance from the specific end face of the vertical axis can be measured along the vertical axis of the stack.

[0038] The method includes a checking step, wherein the temperature signal generated by the temperature sensor is checked to determine whether it represents a temperature below a predetermined temperature threshold. If so, load power regulation independent of the temperature signal is performed. The fact that load power regulation is independent of the temperature signal likely means that the temperature signal is not considered in the load power regulation. In particular, the temperature signal cannot form an input signal for load power regulation.

[0039] The exemplary load power regulation independent of temperature signals is explained in more detail below.

[0040] Therefore, the temperature signal represents the temperature of at least a portion of the battery single-cell stack in the region away from the first end face (i.e., in the region on the thermal passive side).

[0041] According to the present invention, temperature sensors for detecting temperature only need to be installed on the thermal passive side rather than on the thermal active side, which advantageously leads to more cost-effective production of battery systems with fewer temperature sensors, and load power regulation independent of the temperature signal can ensure safe operation. The overhead required for connecting the signal technology of the temperature sensors is also reduced, thereby further reducing manufacturing costs and the likelihood of failure. Since the thermal active side is actively conditioned, and in particular cooled, it can be assumed that it will not rise to a temperature above the maximum permissible operating temperature, or will not rise to a temperature above the maximum permissible operating temperature before the thermal passive side. In other words, it can be assumed that thermal critical overheating occurs only or first in the region of the thermal passive side. Therefore, monitoring the temperature of the thermal passive side is sufficient to ensure safe operation when heated to the critical temperature, particularly by initiating derating based on the temperature signal. Due to load power regulation independent of the temperature signal, safe operation can also be ensured at operating temperatures below the maximum permissible operating temperature without recording the temperature of the thermal active side. Especially in the case of loads with strong cooling performance and resulting large temperature differences within a single battery cell, aging processes such as lithium deposition can be reliably avoided by load power regulation independent of the temperature signal.

[0042] In another embodiment, if the indicated temperature is greater than or equal to a temperature threshold, temperature-dependent load power regulation of the individual battery cell is performed. Specifically, in this case, thermal derating can be performed, i.e., the charging power, and particularly the discharging power, can be reduced. As mentioned above, this increases operational safety because exceeding the maximum permissible temperature and associated aging and / or damage can be avoided.

[0043] In another embodiment, the temperature control device operates based on the temperature detected by the temperature sensor. For example, the temperature control device may operate in a temperature-controlled manner, particularly in a manner that minimizes the difference between the theoretical temperature and the temperature detected by the temperature sensor.

[0044] In another embodiment, a method for voltage control operation of the battery system is implemented for load power regulation independent of temperature signals. This method is explained in DE 10 202 1 203 390 B3, which has already been explained at the beginning. Specifically, it is described that if a destructive process is assumed as a limiting factor, the determination of the maximum charging current results in a voltage trajectory that is practically independent of temperature. In particular, the battery voltage has no temperature dependence or only a slight temperature dependence relative to the state of charge of a single battery cell. This means that for different single-cell temperatures, the single-cell voltage has a nearly constant process compared to the state of charge of a single battery cell. This allows the load process to be controlled and / or regulated using only a single reference curve. In particular, temperature monitoring of each individual battery cell in the battery system is not required. This eliminates the need for complex temperature monitoring through direct measurement or modeling of each individual battery cell, while ensuring the safe operation of the single battery cells.

[0045] Alternatively, load power regulation independent of temperature signals can be performed based on individual pool attributes. Individual pool attributes can be, in particular, individual pool (internal) pressure and / or individual pool thickness and / or individual pool internal resistance and / or individual pool capacity, and can be independent of individual pool temperature.

[0046] The charging power can be adjusted or modified based on this single-cell attribute, particularly in a way that minimizes the deviation between the actual and theoretical values ​​of the single-cell attribute. The actual values ​​of the corresponding variables can be recorded using sensors or determined mathematically based on other recorded variables.

[0047] For example, high-precision coulombic methods can be used to determine the properties of a single pool.

[0048] Actual and theoretical values ​​can be values ​​that depend on the operating state, especially the state of charge. Theoretical values ​​can be predetermined for different operating states, especially the state of charge, in a way that prevents damage to individual battery cells when actual values ​​are set to theoretical values.

[0049] To determine the theoretical value, a voltage curve dependent on the operating conditions can be established, such as the process of battery voltage relative to load conditions, where the single-cell properties dependent on the operating conditions, i.e., the theoretical single-cell properties, are determined based on the voltage curve established in this way. This voltage curve can be determined in various ways, such as based on measurements of a three-electrode laboratory single cell or using high-precision coulometric methods.

[0050] For example, when using a 3-electrode laboratory single cell, the reference electrode can be adjusted to a specific anode potential. When using a 3-electrode laboratory single cell, it is also meaningful to determine the theoretical single-cell properties by converting the battery properties determined based on the laboratory single cell into the properties of a battery in actual use, and / or by considering predetermined safety margins.

[0051] Alternatively, the voltage profile (and therefore the theoretical single-cell properties) can be determined based on simulation, such as a semi-single-cell model, or based on a predetermined allocation, such as in the form of a lookup table.

[0052] Even in temperature ranges below the maximum permissible temperature, this advantageously leads to a high level of operational reliability, as the proposed method enables damage-free charging of individual battery cells within this temperature range.

[0053] In another embodiment, the first end face is arranged in a plane formed by the stack's longitudinal axis and transverse axis. At least one temperature sensor is arranged in the central region of the single-cell stack along a spatial direction parallel to the stack's longitudinal axis and / or along a spatial direction parallel to the stack's transverse axis. The central region can be, for example, an area whose limiting value is spaced from a particular end face of the axis by more than 0.2 times, preferably more than 0.4 times, the dimension along the corresponding axis. Since it can be assumed that the single-cell stack heats up fastest or most intensely in the central region, operational safety can be advantageously ensured particularly well.

[0054] In another embodiment, the battery system includes multiple temperature sensors arranged in a separated region, the sensors being arranged according to specific heat exchange characteristics of a portion of the battery cell stack. Specifically, region-specific temperature sensors can be provided to detect the temperature of a portion of the region if, under a predetermined operating state of the battery system, the temperature of that region does not exceed a predetermined level or has a temperature change rate less than a predetermined threshold, which can be altered by heat transfer, particularly by a reduction. Heat transfer can be to adjacent regions, particularly passive heat transfer, i.e., heat transfer not caused by work.

[0055] Additional temperature sensors can be arranged in predetermined sections of the battery single-cell stack that are directly exposed to heat input from heat sources, such as relays, power electronic components, contactors, fuses, or high-voltage connectors. The fact that these sections are directly exposed to heat input implies that the thermal conductivity of the heat transfer path between the heat source and the predetermined section is greater than a predetermined thermal conductivity.

[0056] In another embodiment, the distribution density of temperature sensors in the battery system varies along a spatial direction parallel to the longitudinal axis of the stack and / or along a spatial direction parallel to the transverse axis of the stack. The distribution density can be, for example, the number of temperature sensors per predetermined unit length. The predetermined unit length can in particular be the maximum distance between two adjacent temperature sensors along the corresponding spatial direction. Specifically, fewer temperature sensors can be arranged along the spatial direction in the edge regions of the battery single-cell stack than in the aforementioned central region. Alternatively or cumulatively, the distribution density in the edge regions can be lower than that in the central region. This advantageously results in a good trade-off between improved operational safety (because temperatures are recorded in several partial regions) and manufacturing costs (because temperatures are recorded only in critical partial regions). It can be assumed here that the edge regions heat up more slowly or more intensely compared to the central region, and that overheating is less likely to occur in these edge regions preceding the central region.

[0057] In another embodiment, the measurement accuracy of the temperature sensor is set to different measurement accuracies for different temperature ranges. It can be assumed that the temperature sensor has adjustable measurement accuracy. Such a temperature sensor can be, for example, an NTC sensor (negative temperature coefficient sensor). For example, the measurement accuracy for a specific region can be adjusted by arranging a series resistor. By selecting the series resistor, the sensitivity of the voltage divider used by the NTC can be adjusted within certain temperature ranges, thereby improving the measurement accuracy within those temperature ranges. However, using an NTC as a temperature sensor and setting the measurement accuracy via a series resistor is purely exemplary. Of course, alternative temperature sensors and / or alternative methods for setting the measurement accuracy can also be used.

[0058] As a result, operational safety can be further improved while manufacturing costs can be reduced. This is especially possible because the temperature sensor does not need to have the same measurement accuracy across the entire range of possible operating temperatures of a single battery cell stack, which allows the use of relatively inexpensive temperature sensors.

[0059] In another embodiment, the measurement accuracy within a first temperature range is lower than that within another temperature range, the maximum value of the first temperature range is less than the minimum value of the other temperature range, and the difference between a temperature threshold and the minimum value is less than the difference between a temperature threshold and the maximum value. This other temperature range may, in particular, include the temperature threshold as previously explained. This may, in particular, be greater than the minimum value of the other temperature range. The maximum value of the other temperature range may be greater than or equal to the temperature threshold. This advantageously leads to further improvements in operational reliability because, in particular, the detection of temperatures approaching or even exceeding a predetermined temperature threshold with relatively high measurement accuracy, and the subsequent possible initiation of temperature-dependent load power regulation, is based on a relatively accurate temperature value.

[0060] A battery system for a vehicle is also proposed, comprising a battery cell stack having multiple individual cells, a temperature control device for each individual cell, and at least one temperature sensor for temperature control located on a first end face of the battery cell stack, and the at least one temperature sensor disposed in a region of the battery cell stack opposite to the first side. This has already been explained previously.

[0061] The battery system also includes at least one control and evaluation device configured to perform a method for operating the battery system according to one of the embodiments described in this disclosure. Therefore, the technical advantages described therein can be achieved using this device.

[0062] The control and evaluation device can be designed as a computing device, which may be a microcontroller or an integrated circuit, or may include a microcontroller or an integrated circuit. Specifically, the control and evaluation device can be used to receive a temperature signal generated by a temperature sensor, and can execute interpreted test steps, and, if necessary, perform load power regulation independent of and dependent on the temperature signal. A temperature control device can also operate in conjunction with the control and evaluation device.

[0063] A vehicle, particularly an electric or hybrid vehicle, is further described having a battery system according to one of the embodiments described in this disclosure. Attached Figure Description

[0064] The invention will be explained in more detail using exemplary embodiments. The accompanying drawings illustrate:

[0065] Figure 1 A schematic flowchart of the method according to the present invention is shown.

[0066] Figure 2 A schematic block diagram of a battery system according to the present invention is shown.

[0067] Figure 3a A schematic perspective view of a single-cell battery stack is shown.

[0068] Figure 3b A schematic perspective view of a single-cell battery stack is shown.

[0069] Figure 4a This shows the unadjusted sensor characteristics.

[0070] Figure 4b The adjusted sensor characteristics and

[0071] Figure 5 Schematic time curves of temperature, charging power, and state of charging are shown when the method according to the invention is used. Detailed Implementation

[0072] In the following text, the same reference numerals denote elements having the same or similar technical characteristics.

[0073] Figure 1 A battery system 1 for operating a vehicle according to the present invention is shown (see Figure 2 A schematic flowchart of the method is provided. In this method, in the test step S1, it is checked whether the temperature signal TS, generated by the temperature sensor 5 of the battery system 1 and representing the temperature of a portion of the battery cell stack 2, is less than a predetermined temperature threshold. If this is the case, then in the normal operation step S2, load power regulation of the battery system 1, independent of the temperature signal, is performed, specifically by the control and evaluation device 6. If this is not the case, then in the safe operation step S3, load power regulation of the battery system 1, dependent on the temperature signal, is performed, specifically using the control and evaluation device 6. For this purpose, the temperature signal TS can be transmitted to the control and evaluation device 6. In particular, by using this load power regulation dependent on the temperature signal, charging power can be throttled to prevent the temperature from rising further or falling further.

[0074] Load power regulation dependent on temperature signals can be performed in particular according to the method used for voltage control operation of battery system 1. This has already been explained earlier.

[0075] The control and evaluation device can also control or adjust the operation of the temperature control device 4 based on the temperature signal TS.

[0076] Figure 2 A schematic block diagram of a battery system 1 according to the present invention is shown. The battery system 1 includes a battery cell stack 2 having multiple individual battery cells 3, a device 4 for temperature control of the individual battery cells 3, at least one temperature sensor 5, and a control and evaluation device 6. It is connected to the temperature sensor 5 for signaling purposes. The temperature sensor 5 generates a temperature signal TS, which represents the temperature of a portion of the battery cell stack 2. This is transmitted to the control and evaluation device 6. This is used to perform... Figure 1 The method shown includes test steps S1 and normal operation steps S2 or safe operation steps S3.

[0077] Figure 2 The diagram shows that the individual battery cell 3 is rectangular in shape. The coordinate system assigned to the battery cell stack 2 is also shown, which has a stack longitudinal axis x and a stack transverse axis y (which lies in...). Figure 2 (Centered perpendicular to the plane of the diagram) and the stack perpendicular to the z-axis. Figure 2 The arrows in the diagram indicate the directions of the x, y, and z axes, forming a Cartesian coordinate system. Each battery cell 3 can then extend with a cell length along the stack's longitudinal axis x, a cell width along the stack's transverse axis y, and a cell height along the stack's vertical axis z.

[0078] In the battery cell stack 2, individual battery cells 3 are arranged one after another along the stack's longitudinal axis x. The battery cell stack 2 has two longitudinal axis-specific end faces Sx1 and Sx2 along the stack's longitudinal axis x, oriented orthogonally to the stack's longitudinal axis x. These correspond to the longitudinal axis-specific end faces of the first and last battery cell 3 in the battery cell stack 2. Furthermore, the battery cell stack 2 has two transverse axis-specific end faces Sy1 along the stack's transverse axis y, oriented orthogonally to the stack's transverse axis y. These end faces Sy1 can be composed of battery cell-specific transverse axis-specific end faces. The battery cell stack 2 also has two vertical axis-specific end faces Sz1 and Sz2 along the stack's vertical axis z, oriented orthogonally to the stack's vertical axis z. These end faces can be composed of battery cell-specific vertical axis-specific end faces.

[0079] A battery temperature control device 4 is arranged on the first end face of the battery single-cell stack 2, specifically on one of the two vertical axis-specific end faces Sz2. At least one temperature sensor 5 is arranged in the region of the battery single-cell stack 2 opposite to this first end face. The device 4 and the temperature sensor 5 are arranged in different spatial halves relative to a reference plane 7, which is orthogonal to the stack vertical axis z and intersects the battery single-cell stack 2 at the middle (i.e., at half its height along the stack vertical axis z).

[0080] Figure 2 The battery system 1 is shown to include just one temperature sensor 5, which is arranged on a specific end face Sz1 of the remaining vertical axis.

[0081] Figure 3a A schematic perspective view of a battery cell stack 2 of a battery system 1 according to another embodiment of the present invention is shown. The battery system 1 includes a temperature control device 4 designed as a cooling plate, disposed on a second vertical axis-specific end face Sz2 of the battery cell stack 2. This forms the thermally active side of the battery cell stack 2. The battery system 1 also includes three temperature sensors 5a, 5b, and 5c, disposed in a region of the battery cell stack 2 opposite to the second vertical axis-specific end face Sz2, disposed on a first transverse axis-specific end face Sy1 of the battery cell stack 2. A terminal 8 of a battery cell 3 is also shown; for clarity, only one battery cell 3 and one terminal 8 are indicated by reference numerals. Connectors are also disposed on the first transverse axis-specific end face Sy1.

[0082] However, it is also true. Figure 2 As shown, the temperature control device 4 and temperature sensors 5a, 5b, and 5c are arranged in different spatial halves about a reference plane 7, which is orthogonal to the stack vertical axis z and intersects the single-cell stack 2 centrally (i.e., at half its height along the stack vertical axis z). A conductor circuit 9 is also shown, through which the temperature sensors 5a, 5b, and 5c are connected... Figure 2The control and evaluation device 6 shown is for signal purposes.

[0083] The first and third temperature sensors 5a and 5c are arranged along the longitudinal axis x of the stack in the edge region of the single-cell battery stack 2. The second temperature sensor 5b is arranged in the central region. In the exemplary embodiment shown, the central region is a region arranged along the length L of the single-cell battery stack 2, ranging from 1 / 3 (inclusive) to 2 / 3 (inclusive) of that length, which is measured along the longitudinal axis x of the stack. Therefore, the first edge region is the region from a specific end face Sx1 (inclusive) of the first longitudinal axis to 1 / 3 (exclusive) of the length, and the other edge region is the region from 2 / 3 (exclusive) of the length to a specific end face Sx2 (inclusive) of the second longitudinal axis.

[0084] Figure 3b A schematic perspective view of a single-cell battery stack 2 of a battery system 1 according to another embodiment of the present invention is shown. Figure 3a In contrast to the embodiment shown, battery system 1 includes four temperature sensors 5a, 5b, 5c, and 5d. The first temperature sensor 5a and the fourth temperature sensor 5d are arranged along the stack's longitudinal axis x about... Figure 3a The illustrated embodiment explains the edge region.

[0085] However, the second and third temperature sensors 5b and 5c are arranged in the central region. Therefore, the distribution density of temperature sensors 5a, 5b, 5c, and 5d varies along a spatial direction parallel to the longitudinal axis x of the stack.

[0086] Figure 4a The sensor characteristic curve of the temperature sensor 5, which is not suitable for the method according to the invention, is shown. The operating temperature range 10 of the battery pack stack 2 is shown, which includes temperatures from -30°C to +55°C. Here, the temperature sensor 5 can detect the temperature with a measurement accuracy of ±3°C in a first temperature range 11 from -60°C to -20°C, and with a measurement accuracy of ±2°C in another temperature range 12 from 20°C to 65°C.

[0087] Figure 4b A sensor characteristic curve for a temperature sensor 5 suitable for the method according to the invention is shown. The operating temperature range of the battery pack 2 is shown again, encompassing temperatures from -30°C to +55°C. Here, the temperature sensor 5 can detect temperature with a measurement accuracy of ±4°C in a first temperature range 11 from -60°C to 50°C, and with a measurement accuracy of ±1°C in another temperature range 12 from 50°C to 65°C. If we assume test step S1 (see...) Figure 1The predetermined temperature threshold used in the test is 55°C, which is the upper limit of the operating temperature range of 10. This shows that the adjusted sensor characteristic curve can more accurately detect temperatures within this upper limit. In particular, this minimizes the risk of erroneously measuring temperatures below 55°C when the actual temperature is above 55°C.

[0088] Figure 5 A schematic time curve of temperature T1, charging power P1, and state of charge SOC1 is shown, indicated by solid lines, when using the method according to the invention, along with corresponding time curves T2, P2, and SOC2 according to the prior art method, which also takes into account the temperature signal from a temperature sensor disposed in the first end face region. It can be seen that, using the method according to the invention, relatively high charging power, relatively high state of charge, and a small difference from the maximum permissible operating temperature Tmax can be achieved, while ensuring that the maximum permissible operating temperature Tmax is not exceeded. The maximum permissible operating temperature Tmax may correspond to a predetermined temperature threshold used in test step S1.

[0089] List of reference numerals

[0090] 1. Operating System

[0091] 2 Battery stack

[0092] 3 single-cell battery

[0093] 4. Battery temperature control device

[0094] Temperature sensors 5, 5a, 5b, 5c, and 5d

[0095] 6. Control and Evaluation Unit

[0096] 7. Reference Plane

[0097] 8 terminals

[0098] 9. Conductor Circuits

[0099] 10 Operating temperature range

[0100] 11 First temperature range

[0101] 12 Wider temperature range

[0102] S1 Test Procedure

[0103] S2 Normal Operating Procedures

[0104] S3 Safe Operation Procedures

[0105] TS temperature signal

[0106] Time curves of temperatures T1 and T2

[0107] Time curves of charging power of P1 and P2

[0108] x Heap longitudinal axis

[0109] y-axis of the stack

[0110] z-pile vertical axis

[0111] Specific end faces of longitudinal axes Sx1 and Sx2

[0112] Sy1 Horizontal Axis Specific Front

[0113] Sz1, Sz2 Vertical axis specific end faces

Claims

1. A method for using a battery system to operate a vehicle, wherein, The battery system includes a battery cell stack having multiple individual battery cells, a temperature control device for each individual battery cell, and at least one temperature sensor. The temperature control device is located on a first end face of the battery cell stack, and the at least one temperature sensor is disposed in a region of the battery cell stack opposite to the first end face. The method includes the following steps: a) Check whether the temperature signal generated by the temperature sensor represents a temperature lower than the predetermined temperature threshold. b) If the indicated temperature is less than the temperature threshold, then load power regulation independent of the temperature signal is performed.

2. The method according to claim 1, characterized in that, If the indicated temperature is greater than or equal to the temperature threshold, load power regulation dependent on the temperature signal is performed.

3. The method according to any one of the preceding claims, characterized in that, The temperature control device operates based on the temperature detected by the temperature sensor.

4. The method according to any one of the preceding claims, characterized in that, In order to perform load power regulation independently of temperature signals, a method for voltage control of the battery system is implemented, or load power regulation independently of temperature signals is performed based on individual cell pressure and / or individual cell thickness and / or individual cell internal resistance.

5. The method according to any one of the preceding claims, characterized in that, The first end face is arranged in a plane formed by the stack longitudinal axis and the stack transverse axis, wherein at least one temperature sensor is arranged in the central region of the single cell stack in a spatial direction parallel to the stack longitudinal axis and / or in a spatial direction parallel to the stack transverse axis.

6. The method according to claim 5, characterized in that, The battery system includes multiple temperature sensors arranged in the separated region, the multiple temperature sensors being arranged according to the specific heat exchange characteristics of a portion of the battery cell stack.

7. The method according to claim 5 or 6, characterized in that, The distribution density of multiple temperature sensors varies along a spatial direction parallel to the longitudinal axis of the stack and / or a spatial direction parallel to the transverse axis of the stack.

8. The method according to any one of the preceding claims, characterized in that, The temperature sensor's measurement accuracy is set to different levels for different temperature ranges.

9. The method according to claim 8, characterized in that, The measurement accuracy in a first temperature range is less than the measurement accuracy in another temperature range, wherein the maximum value in the first temperature range is less than the minimum value in the other temperature range, and wherein the difference between the temperature threshold and the minimum value is less than the difference between the temperature threshold and the maximum value.

10. A battery system for a vehicle, wherein the battery system includes a battery cell stack having a plurality of individual battery cells, a temperature control device for the individual battery cells, and at least one temperature sensor, wherein the temperature control device is disposed on a first end face of the battery cell stack, and at least one temperature sensor is disposed in a region of the battery cell stack facing away from the first side, wherein the battery system includes at least one control and evaluation device and is configured to perform the method according to any one of claims 1 to 9.

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