Electrical energy store having plurality of store branches and disconnection device between store branches

Abstract

The invention relates to an electrical energy store (1) for a motor vehicle for supplying at least one vehicle component of the motor vehicle, comprising at least two store branches (S1, S2, S3, S4) extending geometrically next to one another, each of which has a plurality of connected store units (2), the memory units each have at least one memory cell (3); at least one branch connector (C1, C2, C3) for connecting the memory branches (S1, S2, S3, S4) in series, said branch connector having a breaking device (T1, T2, T3) for detecting and interrupting a fault current circuit (K1, K2, K3, K4) formed by an undesired electrical connection between the two memory branches (S1, S2, S3, S4) and by the at least one branch connector (C1, C2, C3), the disconnecting device (T1, T2, T3) has a controllable disconnecting unit (F1, F2, F3) for disconnecting the at least one branch connector (C1, C2, C3) and a current sensor (I1, I2, I3) for detecting a branch current flowing through the at least one branch connector (C1, C2, C3); and a control device (6), which is designed to detect at least one fault current circuit (K1, K2, K3, K4) as a function of the detected branch current and to actuate the at least one breaking unit (F1, F2, F3) in order to interrupt the fault current circuit (K1, K2, K3, K4).

Description

Technical Field

[0001] The invention relates to an electric energy storage device for a motor vehicle, which is used to supply power to at least one vehicle component of the motor vehicle. The electric energy storage device has a plurality of storage units connected to each other, each of which has at least one storage cell. The invention also relates to a motor vehicle. Background Art

[0002] The present invention concerns an electric energy storage device for a motor vehicle. Such an electric energy storage device can be used, for example, as a traction battery for an electrified motor vehicle, i.e., an electric vehicle or a hybrid vehicle, and supplies energy to at least one vehicle component, such as an electric drive machine. The energy storage device usually has a plurality of interconnected storage cells and usually has a fault current disconnection device for a short circuit occurring outside the storage device. In addition, passive disconnecting elements can be arranged inside the storage device, which are triggered in the case of propagation, for example, caused by the heat diffusion of the fault current. However, based on the specific geometric arrangement of the storage cells with respect to each other, the fault current inside the energy storage device may not flow through the disconnecting element, but through the parasitic fault current path, so that these fault currents cannot be interrupted by the disconnecting element. In addition, the parasitic current path can have an undefined resistance, so that the fault current can be much lower than the rated current of the electric energy storage device. Therefore, the disconnecting element cannot be designed accordingly. These unidentified fault currents can also locally cause critical hot spots and thermal events of the energy storage device even in the state where the electric energy storage device is powered off. Summary of the invention

[0003] The object of the present invention is to provide a simple solution, for example for particularly reliably detecting and disconnecting fault currents within an electrical energy storage device for a motor vehicle.

[0004] This object is achieved according to the invention by an electrical energy storage device and a motor vehicle having the features according to the respective independent claims. Advantageous embodiments of the invention are the subject of the dependent claims, the description and the drawings.

[0005] The electric energy storage device for a motor vehicle according to the present invention is used to supply power to at least one vehicle component of the motor vehicle. The electric energy storage device has at least two storage branches extending geometrically side by side, each of which has a plurality of connected storage cells, each of which has at least one storage cell. In addition, the electric energy storage device has at least one branch connector for connecting the storage branches in series, and the branch connector has a disconnecting device for identifying and interrupting a fault current loop formed by an undesired electrical connection between the two storage branches and by the at least one branch connector. The disconnecting device has a controllable disconnecting unit for disconnecting the at least one branch connector and a current sensor for detecting a branch current flowing through the at least one branch connector. In addition, the electric energy storage device has a control device, which is designed to identify a fault current loop based on the detected branch current and to control the disconnecting unit to interrupt the fault current loop.

[0006] The present invention also relates to a motor vehicle, comprising an electric energy storage device according to the present invention and at least one vehicle component electrically connected to the energy storage device. The electric energy storage device is in particular a high-voltage energy storage device and is used as a traction battery for an electrified motor vehicle. The at least one vehicle component can be, for example, an electric drive machine, which is supplied with electric energy by a traction battery to drive the motor vehicle. The electric energy storage device has a plurality of storage cells or battery cells, which are arranged in a plurality of branches. This means in particular that the storage cells in a branch are arranged geometrically linearly, i.e. in rows or columns. The storage cells are preferably connected in series in this branch. The storage cells each have at least one storage cell or battery cell. For example, each storage cell can also have the interconnection of a plurality of energy storage cells. Preferably, the storage cell is configured as a round cell. However, the storage cell can also be configured as a prismatic cell or a bag cell.

[0007] Each branch is electrically connected in series here, but geometrically extends side by side. In particular, the branches have the same extension direction and extend parallel to each other. Through this geometric arrangement of the storage units in the respective branches and between the branches, each storage unit has at least one adjacent storage unit in the same storage branch and at least one adjacent storage unit in the adjacent storage branch. In addition, the electrical energy storage device can have at least one temperature regulating element for regulating the temperature of the storage unit, and the temperature regulating element extends through the energy storage device transversely to the extension direction of the branch. In the case of a circular unit, a plurality of temperature regulating elements in the form of corrugated temperature regulating coils in strips are particularly provided, which are locally arranged against the cylindrical unit housing of the storage unit. The temperature regulating element can, for example, guide a fluid in order to transport the waste heat of the storage unit away and / or transfer the heating heat to the storage unit.

[0008] In order to connect the branches, at least one branch connector is provided. The branch connector can be configured as a metal busbar, for example. The branch connector connects two adjacent ends of two adjacent branches transversely to the extension direction. The first and last branches of the electric energy storage are connected to terminals in the form of positive and negative poles of the electric energy storage. In the case of an electric energy storage having at least three branches extending side by side, the total current path of the electric energy storage extends geometrically in a meandering manner from one terminal of the electric energy storage through the interconnection circuit of the storage cells to another terminal of the electric energy storage.

[0009] Based on this special arrangement of the branches to each other, a parasitic, undesirable fault current path may be formed between two directly adjacent or spaced branches. Such a fault current path may be generated, for example, by a defective insulation of the at least one temperature control element. The at least one temperature control element usually has a metal fluid conductor, which has an insulating layer because the temperature control element is arranged close to the metal cell housing of the storage cell. If the insulating layer is defective at two locations in the area of ​​two parallel branches, a parasitic fault current path can be formed between the two branches through the metal fluid conductor. A parasitic current path can also be formed between the two branches in other ways, for example, by conductive particles deposited in the energy storage device. A parasitic fault current loop is formed by this parasitic current path and the at least one branch connector connecting the branches, in which the fault current can still circulate even in a state where the electrical energy storage device is powered off, for example, disconnected from the at least one vehicle component. Such a fault current inside the storage device can cause local overheating and thus a thermal event of at least one storage cell, which in the worst case can cause thermal breakdown of the entire electrical energy storage device.

[0010] In order to prevent this situation, the fault current loop is interrupted when the fault current path is identified. For this reason, in particular, each branch connector of the electric energy storage device has a circuit breaker that can be controlled by a control device. The control device can be integrated into a controller inside the storage device or outside the storage device, or can be configured as a separate controller. Each circuit breaker has at least one controllable circuit breaker unit. The controllable circuit breaker unit is preferably configured as a high-temperature fuse. Such a high-temperature fuse has, for example, an ignition unit or a detonator, which activates a circuit breaker element to mechanically disconnect the branch connector. The detonator can be ignited by the control device. In addition, each circuit breaker has a current sensor, which detects the branch current flowing through the branch connector. Based on the detected branch current, it can be identified whether there is a parasitic current path from the branch to another branch.

[0011] For example, the electric energy storage device may have a total current sensor for detecting the interconnected circuit flowing through the branch, and the control device is designed to compare the branch current with the total current, and if the deviation of the branch current from the total current exceeds a predetermined threshold value, a fault current loop is identified. Since the branches are connected in series, the branch currents must be equal to the total current in a non-defective state. If at least one of the branch currents deviates from the total current, this indicates that a fault current loop exists. Instead of or in addition to the comparison with the total current, in the case of at least three storage branches connected in series, the control device can be designed to compare the branch currents with each other, and according to the comparison, at least one fault current loop is identified and the disconnection unit of the corresponding branch connector is controlled to interrupt the relevant fault current loop. Since the branch currents in the series circuit are also necessarily equal in the case of no defects, the fault current loop can also be identified according to the deviation of the fault currents from each other and / or from the total current. Subsequently, the disconnection unit of the branch connector that guides the branch current that deviates from the total current is controlled by the control device. As a result, the fault current loop guided by the branch connector is disconnected and thermal breakdown of the electric energy storage device can be reliably prevented.

[0012] It has proven to be advantageous that the electric energy storage device has a protective device, which is designed to additionally interrupt the current between the electric energy storage device and the at least one vehicle component when a fault current loop is detected. The protective device is designed to de-energize the electric energy storage device. For example, the protective device can be integrated in the control device and send a signal to the at least one vehicle component so that the vehicle component stops drawing current from the electric energy storage device. The protective device can also have a fuse and / or a controllable switching device, which, for example, has a contactor, which disconnects the terminals of the electric energy storage device from the interconnection circuit formed by the branches and / or from the terminals of the at least one vehicle component. With the help of the protective device, it is possible to prevent the current from continuing to be conducted through the fault current path of the interconnection circuit.

[0013] The embodiments presented with regard to the electrical energy store according to the invention and their advantages apply correspondingly to the motor vehicle according to the invention.

[0014] Further features of the invention are apparent from the claims, the drawings and the description of the drawings. The features and feature combinations mentioned above in the description and the features and feature combinations mentioned below in the description of the drawings and / or shown individually in the drawings can be used not only in the respectively given combination but also in other combinations or individually. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will now be described in detail according to preferred embodiments and with reference to the accompanying drawings. The accompanying drawings are as follows:

[0016] Figure 1shows a schematic design of an electrical energy storage device for a motor vehicle; and

[0017] Figure 2 Show according to Figure 1 Possible fault current paths of the electrical energy storage device. DETAILED DESCRIPTION

[0018] In the figures, identical elements and elements having the same function are provided with the same reference symbols.

[0019] Figure 1 An electrical energy storage device 1 is shown, which can be used, for example, as a rechargeable traction battery or traction storage battery for an electric vehicle or hybrid vehicle. The electrical energy storage device 1 has terminals A+, A-, via which the electrical energy storage device 1 can be connected to at least one vehicle component of a motor vehicle. The electrical energy storage device 1 has four series-connected storage branches S1, S2, S3, S4, which are arranged geometrically side by side or in parallel. Each storage branch S1, S2, S3, S4 has a plurality of storage cells 2, which each have a storage cell 3. The storage cells 2 and therefore the storage cells 3 are connected in series. The first storage branch S1 is connected to the first terminal A+ (here the positive pole) of the electrical energy storage device 1 and the fourth storage branch S4 is connected to the second terminal A- (here the negative pole) of the electrical energy storage device 1. The first and second branches S1, S2 are connected in series via a first branch connector C1. The second and third branches S2, S3 are connected in series via a second branch connector C2 and the third and fourth branches S3, S4 are connected in series via a third branch connector C3. The branches S1, S2, S3, S4 and the branch connectors C1, C2, C3 form a meandering arrangement of the memory cells 2.

[0020] In addition, the electrical energy storage device 1 has a plurality of temperature control elements 4, which are arranged transversely to the extension direction of the branches S1, S2, S3, S4 and partially abut against the cell housing of the storage cell 3. The temperature control element 4 may have defective locations 5, such as defective insulation, through which an undesirable electrical connection or fault current path may be formed between two storage branches S1, S2, S3, S4. For example, a first connection may be formed between the first and second branches S1, S2, which together with the first branch connector C1 forms a first fault current loop K1. It is also possible to form a second connection between the third and fourth branches S3, S4, which together with the third branch connector C3 forms a second fault current loop K2. The third connection formed between the second and third branches S2, S3 may form a third fault current loop K3 together with the second branch connector C2. The fourth connection between the first and fourth branches S1, S4 may form a fourth fault current loop K4 together with the branch connectors C1, C2, C3. In Figure 2 The fault current loops K1, K2, K3, and K4 are shown in FIG. Figure 2 The temperature control element 4 is not shown. In these fault current loops K1, K2, K3, K4, corresponding fault currents can circulate. Such fault currents circulating inside the storage device do not necessarily have to have a critical value, but the fault currents cannot flow out of the electrical energy storage device 1 through the terminals A+, A- and thus cause local overheating inside the electrical energy storage device 1.

[0021] Therefore, the branch connectors C1, C2, C3 each have a disconnecting device T1, T2, T3. Each disconnecting device T1, T2, T3 has a current sensor I1, I2, I3 for detecting the branch current flowing through the branch connectors C1, C2, C3. In addition, each disconnecting device T1, T2, T3 has a controllable disconnecting unit F1, F2, F3, which can be constructed as a high-temperature fuse, for example. The sensor data of the current sensors I1, I2, I3 can be received by the control device 6, which can also control the disconnecting units F1, F2, F3. In addition, the electrical energy storage device 1 has a total current sensor I4, which can detect the total current of the electrical energy storage device 1.

[0022] The control device 6 can now compare the branch currents of the current sensors I1, I2, and I3 with one another and with the total current of the current sensor I4. If, for example, the branch current of the first current sensor I1 deviates from the branch currents of the other current sensors I2 and I3 and from the total current of the total current sensor I4, the first fault current loop K1 is detected and the first disconnecting unit F1 is actuated to disconnect the first branch connector C1 and thus interrupt the first fault current loop K1. If, for example, the branch current of the second current sensor I2 deviates from the branch currents of the other current sensors I1 and I3 and from the total current of the total current sensor I4, the second fault current loop K2 is detected and the second disconnecting unit F2 is actuated to disconnect the second branch connector C2 and thus interrupt the second fault current loop K2. If, for example, the branch current of the third current sensor 13 deviates from the branch currents of the other current sensors I1 and I2 and from the total current of the total current sensor 14, the third fault current loop K3 is detected and the third disconnecting unit F3 is actuated to disconnect the third branch connector C3 and thus interrupt the third fault current loop K3. If, for example, the branch currents of all current sensors I1, I2, I3 deviate from the total current of the total current sensor I4, the fourth fault current loop K4 is detected and at least one of the disconnecting units F1, F2, F3 is actuated to disconnect at least one branch connector C1, C2, C3 and thus interrupt the fourth fault current loop K4.

[0023] If at least one of the fault current paths K4 is detected, a protective device 7 , such as a fuse, can additionally be activated in order to de-energize the electrical energy store 1 .

Claims

1. An electrical energy storage device (1) for a motor vehicle, the electrical energy storage device being used to supply power to at least one vehicle component of the motor vehicle, the electrical energy storage device comprising: at least two storage branches (S1, S2, S3, S4) extending geometrically next to one another, each of which has a plurality of connected storage cells (2), each of which has at least one storage cell (3), at least one branch connector (C1, C2, C3) for connecting the storage branches (S1, S2, S3, S4) in series, the branch connector having a disconnecting device (T1, T2, T3) for identifying and interrupting a fault current loop (K1, K2, K3, K4) formed by an undesired electrical connection between two storage branches (S1, S2, S3, S4) and by the at least one branch connector (C1, C2, C3), the disconnecting device (T1, T2, T3) having a controllable disconnecting unit (F1, F2, F3) for disconnecting the at least one branch connector (C1, C2, C3) and a current sensor (I1, I2, I3) for detecting a branch current flowing through the at least one branch connector (C1, C2, C3), and A control device (6) is designed to detect at least one fault current loop (K1, K2, K3, K4) based on the detected branch current and to actuate the at least one disconnecting unit (F1, F2, F3) to interrupt the fault current loop (K1, K2, K3, K4).

2. The electrical energy storage device (1) according to claim 1, characterized in that The electrical energy storage device (1) has a total current sensor (I4) for detecting the total current flowing through the interconnected circuits of the storage branches (S1, S2, S3, S4), the control device (6) being designed to compare the at least one branch current with the total current and to identify the at least one fault current loop (K1, K2, K3, K4) if the deviation of the at least one branch current from the total current exceeds a predetermined threshold value.

3. The electrical energy storage device (1) according to claim 1 or 2, characterized in that The electrical energy storage device (1) has a protective device (7) which is designed to additionally interrupt the current flow between the electrical energy storage device (1) and the at least one vehicle component when the at least one fault current loop (K1, K2, K3, K4) is detected.

4. The electrical energy storage device (1) according to claim 1, characterized in that The storage cells (2) of each storage branch (S1, S2, S3, S4) are arranged geometrically linearly and each storage cell (2) has at least one adjacent storage cell (2) in the same storage branch (S1, S2, S3, S4) and at least one adjacent storage cell (2) in an adjacent storage branch (S1, S2, S3, S4).

5. The electrical energy storage device (1) according to claim 1, characterized in that The electrical energy storage device (1) has at least one temperature control element (4) for controlling the temperature of a storage cell (3), the temperature control element extending through the electrical energy storage device (1) transversely to the extension direction of the storage branches (S1, S2, S3, S4) and, in the event of a defect in the insulation, an undesired connection between at least two storage branches (S1, S2, S3, S4) can be established via the temperature control element.

6. The electrical energy storage device (1) as claimed in claim 1, characterized in that The storage cell (3) is constructed as a round cell.

7. The electrical energy storage device (1) according to claim 1, characterized in that The at least one controllable disconnecting unit (F1, F2, F3) is designed as a high-temperature fuse which can be ignited by a control device (6).

8. The electrical energy storage device (1) as claimed in claim 1, characterized in that The electric energy storage device (1) has at least three storage branches (S1, S2, S3) extending side by side, the storage branches are respectively connected in series via a branch connector (C1, C2, C3) respectively having a disconnecting device (T1, T2, T3), the control device (6) is designed to compare the branch currents of the current sensors (I1, I2, I3) of the disconnecting devices (T1, T2, T3) with each other and / or with the total current of the electric energy storage device (1), identify at least one fault current loop (K1, K2, K3, K4) based on the comparison, and control the disconnecting unit (F1, F2, F3) of at least one relevant branch connector (C1, C2, C3) to interrupt the fault current loop (K1, K2, K3, K4). 9 . A motor vehicle comprising at least one vehicle component and at least one electrical energy storage device ( 1 ) according to claim 1 .

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