Battery arrangement for the metrological connection of cell modules and motor vehicle

Abstract

Battery arrangement (40) for a motor vehicle, wherein the battery arrangement (40) has - a battery (42) with a battery housing (44), wherein the battery (42) has two different electrical potentials (HV) + HV - ) provides, - several cell modules (46), each arranged in an associated module housing (48), the module housings (48) being arranged in the battery housing (44), - an insulation monitor (54) designed to measure an insulation resistance between a predetermined electrical ground (58) and at least one of the electrical potentials (HV) + HV -) of the battery (42), characterized in that the module housings (48) are each electrically insulated and attached to the battery housing (44), and the module housings (48) are connected to the predetermined electrical ground (58) via a respective connection (66) which has at least a current-limiting property.

Description

[0001] The invention relates to a battery assembly for a motor vehicle, wherein the battery assembly comprises a battery with a battery housing, and the battery provides two different electrical potentials. Furthermore, the battery assembly comprises a plurality of cell modules, each arranged in an associated module housing, wherein the module housings are arranged in the battery housing. Furthermore, the battery assembly comprises an insulation monitor configured to monitor an insulation resistance between a predetermined electrical ground and at least one of the electrical potentials of the battery.

[0002] Various batteries, particularly HV (high-voltage) batteries for motor vehicles, are known from the prior art. Such HV batteries can, for example, comprise 36 individual cell modules. Such a cell module typically comprises several individual cells electrically connected in series or parallel, or a combination of both. The cell modules are also interconnected, for example, also in a series circuit. For strength reasons, the individual cell modules typically have a metal housing in which the individual cells, for example, lithium-ion cells, are housed.

[0003] Such a battery arrangement is in Fig. 1. Shown here is a battery 10 with a battery housing 12, in which such a cell module 14 with a module housing 16 is arranged. Such cell modules 14 or their housings 16 are usually screwed to the battery housing 12. Such a screw connection can be realized, for example, by a screw 18 that is passed through at least part of the module housing 16 and screwed to a corresponding base 20 on the battery housing 12. By fastening the individual module housings 16 in the battery housing 12, all module housings 16 are electrically connected to one another and to the battery housing 12. Furthermore, such an arrangement usually includes an insulation monitor 22, which monitors the insulation between the HV lines 24 of the battery 10, the battery cells, as well as other parts of the HV system and the vehicle body 26.Furthermore, a corresponding connection between the battery housing 12 and the vehicle body 26 is provided as a potential equalization 28. In the event of an insulation fault, for example a fault in the insulation 30 between an HV component of a cell module 14 and the module housing 16, the module housing 16 and then also the vehicle body 26 are exposed to the potential due to the electrical path 32 leading from the module housing 16 to the vehicle body 26 and to the insulation monitor 22, which is shown in . Fig. 1 is shown in dashed lines, then also at a corresponding HV potential, which can then be detected by insulation monitor 22.

[0004] Such insulation monitoring, which monitors the insulation resistance between the HV potentials and the vehicle body, is also described in DE 10 2013 217 458 A1 and US 2004 / 0130288 A1, for example. Problems with such an arrangement, however, primarily become apparent in the case of a double fault, i.e. a double insulation resistance fault, which can, for example, result in two different module housings being at different HV potentials. In such a double insulation resistance fault case, a very high current flows between the cell modules and their module housings, which are electrically connected to one another via the battery housing. In the best case scenario, this current only leads to rapid self-discharge of the battery, but in the worst case scenario to self-destruction of the battery. Both of these also mean that there will be no voltage present in the foreseeable future, which can lead to the vehicle coming to an immediate standstill or even to the engine shutting down.This could lead to the vehicle breaking down. However, the potential for self-destruction of the battery poses significant safety risks and should therefore be avoided.

[0005] DE 10 2013 220 178 A1 describes a device for testing the electrical insulation of cell housings of a battery module comprising a plurality of battery cells arranged next to one another, which device comprises a measuring device with a first measuring connection for electrically contacting a cell housing of a battery cell, a second measuring connection for electrically contacting a cell terminal of a battery cell of the battery module and an electrically insulating base body with a flat surface for receiving the battery module, wherein the flat surface of the base body has electrically conductive contact elements, so that when the battery module is arranged on the flat surface, a cell housing of a battery cell of the battery module is in each case contacted by a contact element, wherein a contacted contact element can be used in each case as the first measuring connection.

[0006] DE 10 2009 003 048 A1 describes a device for triggering a disconnection of an energy storage device from a connected network, wherein a voltage curve under load can be measured, the measured values ​​can be compared with a reference value and, in the event of a deviation outside a tolerance range, a disconnection of the energy storage device from the network can be triggered.

[0007] The object of the present invention is therefore to provide a battery arrangement and a motor vehicle by means of which both a first fault can be detected and at the same time the risk of self-destruction of the battery in the event of a double insulation resistance fault can be reduced in the simplest possible manner.

[0008] This object is achieved by a battery arrangement and a motor vehicle having the features according to the respective independent claims. Advantageous embodiments of the invention are the subject of the dependent patent claims, the description, and the figures.

[0009] The battery arrangement according to the invention for a motor vehicle comprises a battery with a battery housing, wherein the battery provides two different electrical potentials. Furthermore, the battery arrangement comprises a plurality of cell modules, each arranged in an associated module housing, wherein the module housings are arranged in the battery housing. In addition, the battery arrangement also comprises an insulation monitor designed to monitor an insulation resistance between a predetermined electrical ground and at least one of the electrical potentials of the battery. The module housings are each fastened in the battery housing in an electrically insulated manner, and the module housings are connected to the predetermined electrical ground via a respective connection having at least a current-limiting property.

[0010] A connection with at least a current-limiting property can be understood as a connection with a current-limiting but not current-interrupting property, such as a predetermined high-impedance connection, as well as a connection with a current-interrupting property, for example a fused connection. This advantageously ensures that the individual module housings are no longer connected to one another via the battery housing with low impedance or without protection. The predetermined high-impedance or fused metrological connection of the individual module housings to the insulation monitor and the insulated fastening of the module housings in the battery housing realized by the invention can advantageously prevent current flow via fastening elements such as screws and bases and other conductive and very low-impedance elements in the event of a double fault.In the event of a double insulation resistance fault, this can also advantageously prevent self-destruction of the battery. Furthermore, the insulation monitor's full functionality is maintained, since a low-resistance connection between the individual module housings and the battery housing is not necessary for its proper functioning. For example, a contact resistance of 1 kOhm would also be suitable, allowing the respective high-resistance connections to have a resistance in the kiloohm range without impairing the insulation monitor's functionality.

[0011] The battery is preferably an HV battery. The individual cell modules of this battery, which may each comprise several individual cells, such as lithium-ion cells, for example in a series circuit, can also be connected in series or in parallel circuits or combinations thereof. The various potentials of the battery can be provided via a positive pole and a negative pole of the battery, and the predetermined ground is preferably realized via the vehicle body of the motor vehicle. In addition, the insulation monitor is preferably also designed to monitor the insulation resistance between the ground and both electrical potentials of the battery, as this enables a more precise determination of the insulation resistance.

[0012] There are numerous advantageous possibilities for the design of such a connection with at least the current-limiting property, via which respective module housings are connected to the ground, which are described in more detail below.

[0013] According to one embodiment of the invention, it is provided that at least one of the respective connections is provided by an electrical line, in particular a signal line. The respective connections can thus be provided, for example, by a respective thin wire with a correspondingly small line cross-section, as is the case, for example, with a signal line, which usually has a very small line cross-section. This allows the electrical connection to be realized in a particularly simple and cost-effective manner. The great advantage of designing such an electrical connection as a thin wire or signal line is that, in the event of a fault-related high current flow through such a thin electrical connection, the line can be automatically destroyed and the impermissible current flow can thus be immediately interrupted.It is therefore particularly advantageous if, in general, at least one of the electrical lines is designed such that it is interrupted when a current flows through the at least one electrical line with a current intensity greater than a predetermined limit. As already mentioned, such an interruption can be provided, for example, by the electrical lines being designed to be correspondingly thin so that they automatically melt or burn out when a correspondingly high current flows. In this way, in the event of a double insulation fault, not only can self-destruction of the battery be advantageously prevented, but self-discharge of the battery can also be prevented in a particularly simple and cost-effective manner.However, such an interruption measure does not necessarily have to be achieved by making the respective electrical cables correspondingly thin, but can also be achieved in other ways.

[0014] The respective electrical lines can be electrically connected to one another, in particular directly or indirectly via the battery housing or the vehicle body. Because the electrical lines are designed to interrupt current, for example, by a cross-section in the range of a few square millimeters, for example 0.35 mm 2 , or at least current-limiting, for example with a correspondingly predetermined high-ohmic resistor, the battery does not self-destruct despite the electrically conductive connection between the electrical lines.

[0015] According to a further particularly advantageous embodiment of the invention, it is provided that at least one of the electrical lines has a fuse which is designed to interrupt the electrical line when a current flows through the electrical line with a current intensity greater than a predetermined limit. Such a fuse can accordingly be provided as an overcurrent fuse which causes a line interruption when a corresponding predetermined overcurrent occurs. For example, such a fuse can be easily implemented as a melting fuse. The provision of a fuse also has the great advantage that the location of the line interruption is predetermined by the position of the fuse in the line. If, on the other hand, the line interruption is only implemented by a thin design of the electrical line itself, it is not possible to predict at which point the line will melt in the event of an overcurrent.By making the location of the line interruption predictable by providing appropriate protection at that location, safety can be further increased.

[0016] Furthermore, the electrical lines, designed as a wire or resistor, can be arranged with or without a fuse, for example with a first end on a respective module housing and with a second end, for example, on the battery housing. If the electrical lines are provided, for example, by a respective high-ohm resistor, this is preferably designed such that it melts in the event of a predetermined overcurrent. Alternatively, such a resistor can also be combined with a fuse or a thin line section in order to enable a line interruption in the event of an overcurrent. This provides numerous advantageous options for implementing the respective predetermined high-ohm or fused connections between the module housings and the predetermined ground, thereby providing numerous advantageous measurement connection options to the insulation monitor.

[0017] In a further advantageous embodiment of the invention, the predetermined limit value is dimensioned such that it is exceeded in the event of an insulation resistance fault occurring at least twice. An insulation resistance fault, as already described, represents a fault relating to the insulation between a cell module and the associated module housing. An insulation resistance fault occurring at least twice is accordingly an insulation resistance fault that affects at least two different cell modules or their insulation from the associated module housing, as explained above.

[0018] This embodiment of the invention ensures that, in the event of a double insulation resistance fault, the critical current flow is interrupted or the current level is at least limited. This can be implemented particularly easily using the measures described above, for example, a correspondingly thin signal line or an appropriately dimensioned fuse.

[0019] In a further advantageous embodiment of the invention, the respective lines are designed such that if a current flows through two of these lines due to a double insulation resistance fault, only one of these two lines is interrupted. If a double fault as described above occurs, one of the two electrical lines of a module or the corresponding fuse blows, resulting in an immediate interruption of the impermissible current flow. At the same time, this advantageous embodiment of the invention can ensure that the fault that has occurred continues to be detected by the insulation monitor, since the second, still intact electrical line still allows the insulation monitor to detect the fault. This advantageously ensures that monitoring and fault detection by the insulation monitor continue.This is particularly relevant in the event of a repair, as a person then knows that there is a fault before opening the battery and can prepare and protect themselves accordingly.

[0020] In general, the insulation monitor can be designed to detect when a predetermined minimum insulation resistance falls below a certain threshold, for example, by measuring the current. In the event of a fault, which is then detected, for example, by exceeding the insulation fault current, a corresponding warning can be issued and the fault documented.

[0021] To ensure that only one of the two affected lines is interrupted in the event of a dual insulation resistance fault, special measures are not necessarily required for the design of these electrical lines, as it is highly unlikely that both lines will actually melt or blow the relevant fuses simultaneously. Once the current flow through one of these two lines is interrupted without interrupting the other, the other remains intact because no current flows through it.However, it is also conceivable to design the respective lines slightly differently, for example, with different thicknesses or with respective fuses that trigger at slightly different overcurrents, so that in the event of a double insulation resistance fault, it is guaranteed that one of the two affected lines is always interrupted first and the other is not interrupted, regardless of which two of the multiple electrical lines current flows through in the case of a double fault. Accordingly, the predetermined limit value described above can also be determined slightly differently for the respective electrical lines.

[0022] According to a further advantageous embodiment of the invention, the electrical lines can also be connected to a control device that is designed to detect at least one insulation resistance fault relating to an insulation between a cell module and the module housing assigned to this cell module. The electrical lines therefore do not have to be directly connected from a respective module housing to the battery housing and via this to the body, but can also be indirectly connected to ground via the control device. Accordingly, for example, a respective electrical line can be arranged with a first end on a module housing and coupled with the second end to the control device. The corresponding electrical lines can thus also be connected to the predetermined ground in a galvanically isolated manner.This control device can now advantageously implement fault detection and, optionally, fault localization or other advantageous functions. For example, the control device can also be designed to cause a severing of at least one of the affected electrical lines through which current flows due to the fault, in the event of the detection of an insulation resistance fault, in particular a double insulation resistance fault.This eliminates the need to create a suitable design for the electrical lines themselves, for example, by making them thin enough or by using an overcurrent fuse. Numerous other advantageous options are available for severing one of the affected electrical lines in the event of a double insulation resistance fault, such as opening a switch, triggering a pyroelectric fuse, or other measures for separating the two electrically connected electrical lines affected by the double insulation resistance fault using the control device. The provision of a control device also enables numerous other advantageous configurations.For example, no measures need to be taken to interrupt the lines if, for example, the respective electrical lines are electrically connected to the control device but not to each other.

[0023] Therefore, a further advantageous embodiment of the invention is that the electrical lines are not electrically conductively connected to one another. This means that even in the event of a double insulation resistance fault, no current can flow between the respective affected electrical lines, even without having to provide a means of severing the electrical lines. Furthermore, it is also possible for the control device to be designed to monitor the respective potentials of the individual electrical lines that are not connected to one another and to measure them against ground, for example, so that not only a single fault and a double insulation resistance fault can advantageously be detected, but such faults can also be localized. For this purpose, the cell module and its module housing affected by this fault can be determined depending on the respective electrical potential of a respective electrical line.The location of an occurring error or several occurring errors can thus advantageously be stored, for example, in a memory and used for error diagnosis and read out for this purpose.

[0024] Furthermore, the invention relates to a motor vehicle having a battery arrangement according to the invention or one of its embodiments. The advantages described for the battery arrangement according to the invention and its embodiments apply equally to the motor vehicle according to the invention.

[0025] Exemplary embodiments of the invention are described below. Shown are: Fig. 1 is a schematic representation of a battery arrangement according to the prior art; Fig. 2 a schematic cross-sectional view of a battery arrangement according to an embodiment of the invention; Fig. 3 is a schematic representation of a battery arrangement according to a further embodiment of the invention; and Fig. 4 a schematic representation of a battery arrangement according to a further embodiment of the invention.

[0026] The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual, independently considered features of the invention, which also further develop the invention independently of one another and are thus also to be considered as components of the invention, either individually or in a combination other than that shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0027] In the figures, functionally identical elements are provided with the same reference numerals.

[0028] Fig. Figure 2 shows a schematic cross-sectional view of a battery assembly 40 according to an embodiment of the invention. The battery assembly 40 comprises a battery 42 with a battery housing 44 in which several cell modules 46 are arranged, of which Fig. 2, only one is shown as an example. These cell modules 46 are arranged in respective associated module housings 48, which in turn are fastened in the battery housing 44. Such a fastening can be provided, for example, by a screw connection realized by a screw 50 that is passed through at least part of a respective module housing 48 and screwed to a corresponding base 52 of the battery housing 44. However, such a fastening can be designed in any other way. Furthermore, the battery arrangement 40 has an insulation monitor 54, which monitors the insulation between the HV lines 56, or in general the HV potentials, and the vehicle body 58, which provides the ground. A corresponding conductive connection as potential equalization 60 is also provided between the ground, i.e. the vehicle body 58 and the battery housing 44.For stability reasons, the module housings, such as the module housing 48 shown here, are made of metal or an alloy and are therefore electrically conductive. For this reason, an insulation 62 is arranged between the electrical components of the cell module 46 and the respective module housings 48, which electrically insulates the cell modules 46 and their components, such as the battery cells, from the module housing 48.

[0029] Typically, module housings are connected to the ground, i.e., the vehicle body, via their attachment to the battery housing, but are also electrically connected to each other via the low-resistance connection provided by the attachment, via the battery housing. In the event of a single insulation fault, for example, a defect in the insulation between a cell module and the module housing, this can be detected by the insulation monitor according to the state of the art without resulting in any dangerous situations.However, in the event of a double insulation resistance fault, for example, a defect in the insulation surrounding two different cell modules, the module housings may be at different potentials. Due to their low-resistance electrically conductive connection via the fastenings to the common battery housing, a very high current can flow, which can lead to self-destruction of the battery. The inventions and their embodiments now advantageously prevent this by the following measures: On the one hand, the cell modules 46 are arranged and secured in the battery housing 44 in an electrically insulated manner. This can be easily achieved by appropriate insulation 64 between the module housings 16 and the battery housing 44, particularly in the area of ​​the fastening elements, such as the screw 50 and the base 52. Such insulation 64 can be provided, for example, simply by a KTL (catalytic dip painting) layer, or by any other insulation, at the relevant points of the module housing 16 and the battery housing 44 to be insulated. On the other hand, the module housing 48 is further connected to the electrical ground provided by the vehicle body 58 or by the battery housing 44 as part of the vehicle body 58 via a connection 66 with at least a current-limiting property, for example a predetermined high-resistance or fused connection.This connection 66 can be configured, for example, as an electrical line 66, for example, as a signal line, wire, or resistor, from the module housing 48 to the battery housing 44. Furthermore, this electrical line 66 can be configured such that it is destroyed, for example, by melting, above a certain current intensity. Alternatively, the electrical connection 66 can also have a corresponding overcurrent fuse 68, which interrupts the line 66 above a certain overcurrent. The measurement connection via the in . Fig. 2, to the ground 58 of the insulation monitor 54 is advantageously not via the module and battery housing 48, 44 with low resistance, but rather via the electrical line 66 with high resistance or protection. If a double fault as described above occurs, which leads to a current flow through two relevant electrical lines 66, the thin design of the electrical lines 66 or the optional fuse 68 immediately interrupts the impermissible current flow. Nevertheless, such a fault will still be detected by the insulation monitor 54, since the second, still intact electrical line 66 of the other relevant cell module 46 still allows the insulation monitor 54 to detect the fault. The electrical lines 66 can also be designed with a defined resistance for permanent current limitation.In this way, too, in the case of a double insulation resistance fault, the current flow can be limited at least to a level that is not critical with regard to self-destruction of the battery 42, and furthermore, a connection to the insulation monitor 54 is still provided, by which the fault can be detected accordingly.

[0030] Fig. Figure 3 again shows a battery arrangement 40 according to an embodiment of the invention in a slightly different schematic representation. This battery arrangement 40 is designed in the same way as already Fig. 2. Here, the multiple cell modules 46, which in this example are connected in series, can be seen within the battery housing 44. Each of these cell modules 46 can have multiple individual cells 46a, such as lithium-ion cells connected in series. The housings 48 of the respective cell modules 46 are connected to the battery housing 44 via respective electrical lines 66, which can optionally have respective overcurrent fuses 68 or resistors, and via them to the ground or vehicle body 58. This illustration also shows the two potentials HV provided by the battery 42. + and AGM -which provide a voltage that can be tapped at the battery poles, in particular a positive pole 74 and a negative pole 76. This illustration clearly shows that a current flow between two module housings 48 caused by a double insulation resistance fault can be immediately stopped by interrupting one of the two electrical lines 66 through which this fault current flows.

[0031] Thus, in the event of a double insulation resistance fault, a corresponding automatic shutdown within the HV battery 42 is advantageously implemented and effective. In this scenario, the battery 42 would be impaired neither by self-destruction nor by rapid self-discharge. The functionality and repairability of the battery 42, as well as its value, are thus maintained. Furthermore, in such a double fault situation, the vehicle does not come to a standstill or break down. Nevertheless, the insulation monitor 54 fully functions. The insulation fault can thus be advantageously detected both during vehicle operation and during repair and analysis in the workshop.

[0032] In order to Fig. 3 and Fig. In addition to the high-resistance or fused connection 66 described in Figure 2 for connecting the module housing 16 to the ground 58 of the insulation monitor 54, there are numerous other possibilities. Such a connection can also include galvanic isolation. It is also conceivable that the respective electrical lines 66 are not connected directly to the battery housing 44, but rather coupled to a control unit, which can then detect and optionally also localize an insulation fault, as well as a double insulation fault.

[0033] This is shown schematically in Fig. 4, which shows a battery arrangement 40 according to a further embodiment of the invention. The battery arrangement 40 can be configured as already described with the exception of the differences described below. Fig. 3. For reasons of clarity, the battery housing 44 is made of Fig. 3, but it is still present and accommodates the individual battery modules 46. In contrast to the battery arrangement 40 from Fig. 3, the module housings 48 are now directly connected to the insulation monitor 54 via respective connections 66. In particular, the individual connections 66 are not electrically conductively connected to one another. The respective connections 66 can again be protected, for example, with a fuse 68, or, for example, also comprise a resistor. In this configuration, both a single and a double insulation resistance fault can advantageously be detected by the insulation monitor 54 and, moreover, can be localized, since the potentials at the individual connections 66 can now be tapped.

[0034] Overall, the examples show how the invention can be used to implement a metrological connection of cell modules within an HV battery, so that in the event of a double insulation resistance fault, self-destruction and self-discharge of the battery can be avoided in a particularly cost-effective and effective manner.

Claims

[1] Battery arrangement (40) for a motor vehicle, wherein the battery arrangement (40) comprises - a battery (42) with a battery housing (44), wherein the battery (42) has two different electrical potentials (HV + , AGM - ) provides, - a plurality of cell modules (46), each arranged in an associated module housing (48), wherein the module housings (48) are arranged in the battery housing (44), - an insulation monitor (54) designed to measure an insulation resistance between a predetermined electrical ground (58) and at least one of the electrical potentials (HV + , AGM - ) of the battery (42), characterized bythat the module housings (48) are each fastened in the battery housing (44) in an electrically insulated manner, and the module housings (48) are connected to the predetermined electrical ground (58) via a respective connection (66) which has at least a current-limiting property. [2] Battery arrangement (40) according to claim 1, characterized by that at least one of the respective connections (66) is provided by an electrical line (66), in particular a signal line. [3] Battery arrangement (40) according to claim 2, characterized by that the respective electrical lines (66) are electrically conductively connected to one another. [4] Battery arrangement (40) according to claim 2 or 3, characterized by that at least one of the electrical lines (66) is designed such that it is interrupted when a current flows through the electrical line with a current intensity greater than a predetermined limit value. [5] Battery arrangement (40) according to one of claims 2 or 3, characterized by that at least one of the electrical lines (66) has a fuse (68) which is designed to interrupt the electrical line (66) when a current flows through the electrical line (66) with a current intensity greater than a predetermined limit value. [6] Battery arrangement (40) according to one of claims 4 or 5, characterized by that the predetermined limit value is dimensioned such that it is exceeded in the event of an insulation resistance fault (70) occurring at least twice, wherein an insulation resistance fault (70) represents a fault relating to an insulation (62) between a cell module (46) and the associated module housing (48). [7] Battery arrangement (40) according to one of claims 2 to 6, characterized bythat the respective lines (66) are designed in such a way that in the event of a current flow through two of these lines (66) caused by a double insulation resistance fault (70), only one of these two lines (66) is interrupted. [8] Battery arrangement (40) according to one of claims 2 or 4 to 7, characterized by that the electrical lines (66) are connected to a control device which is designed to detect at least one insulation resistance fault (70) relating to an insulation (62) between a cell module (46) and the module housing (48) associated with this cell module (46). [9] Battery arrangement (40) according to claim 8, characterized by that the electrical lines (66) are not electrically connected to one another. [10] Motor vehicle with a battery arrangement (40) according to one of the preceding claims.

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