Battery and vehicle

Abstract

The invention relates to a battery comprising at least two battery cells (1) and a balancing module (2) for performing charge equalization of the battery cells (1), wherein the balancing module (2) is configured to dissipate the excess charge of at least one battery cell (1) via a resistor (3). The battery according to the invention is characterized in that the resistor (3) is thermally connected to one of the battery cells (1).

Description

[0001] The invention relates to a battery of the type defined in more detail in the preamble of claim 1 and to a vehicle with such a battery.

[0002] A secondary battery or accumulator comprises one or more electrically coupled galvanic cells. By connecting several individual cells in series, a desired nominal voltage for such an accumulator can be set. Due to manufacturing and aging, fluctuations in the capacity and internal resistance of the individual cells can occur. This leads to the charge level of the individual cells varying from cell to cell when charging and / or discharging the accumulator. To prevent overcharging or deep discharging of individual cells, charge equalization is carried out between the individual cells. This is also referred to as "cell balancing." A distinction can be made between passive and active balancing.

[0003] A method for balancing the charge of battery cells or a system for balancing battery cells is known, for example, from DE 10 2012 201 332 A1 or EP 3 443 636 B1. The balancing systems known from these two publications are equally capable of performing passive balancing and active balancing. The simultaneous implementation of passive and active balancing is also referred to as hybrid cell balancing.

[0004] The resistors responsible for dissipating excess charge from a battery cell are usually located on a common printed circuit board (PCB). The board can be integrated into the battery's control unit, also known as the battery management system (BMS). This results in a concentration of the resistors responsible for balancing in a relatively small area. This leads to a concentration of the respective dissipation heat, requiring the provision of a separate cooling device to dissipate the dissipation heat in order to prevent local overheating. Inadequate cooling increases the risk of failure of one or more components of the battery management system or the electronic components located on the board, which must be avoided.The provision of a separate cooling device also entails increased manufacturing costs. Furthermore, sufficient space is required to accommodate the cooling device, which increases the development effort and costs of a corresponding battery.

[0005] The present invention is based on the object of providing an improved battery which is capable of carrying out charge equalization and is characterized by a simple construction, improved robustness and a long service life.

[0006] According to the invention, this object is achieved by a battery having the features of claim 1. Advantageous embodiments and further developments as well as a vehicle with such a battery emerge from the dependent claims.

[0007] A generic battery comprising at least two battery cells and a balancing module for carrying out charge balancing of the battery cells, wherein the balancing module is configured to dissipate the excess charge of at least one battery cell at a resistor, is further developed according to the invention in that the resistor is thermally conductively connected to one of the battery cells. By thermally conductively contacting the resistor with the battery cell, the thermal mass of a respective battery cell can be used to absorb the dissipation heat. Typically, the thermal mass of the battery cell is so large that the dissipation heat generated by the resistor does not cause any significant heating of the battery cell. Thus, the provision of a separate cooling device for dissipating the dissipation heat can be dispensed with.This reduces the design effort of the battery according to the invention and lowers development and manufacturing costs. This also eliminates the risk of cooling system failure, which ultimately improves the robustness of the battery according to the invention and thus also its service life.

[0008] According to a first advantageous embodiment of the battery according to the invention, the resistor is thermally conductively connected to the cell housing of the battery cell. This allows the dissipation heat to be introduced directly into the cell housing. Particularly with a cell housing made of metal, the dissipation heat can thus be quickly and evenly supplied to the battery cell. This can also be understood as a direct connection of the resistor to the battery cell. The battery according to the invention can also have a cooling system for cooling the battery cells or be connectable to such a system. Thus, the dissipation heat during charge equalization can be dissipated via the existing cooling system. Furthermore, a separate cooling device for the resistors used for charge equalization can be dispensed with.

[0009] According to an advantageous alternative embodiment of the battery according to the invention, the resistor is thermally conductively connected to a contact element of the battery cell, wherein the contact element is electrically conductively connected to a battery terminal of the battery cell. This enables the dissipation heat emitted by the resistor to be quickly and reliably dissipated into the interior of the battery cell. This can also be understood as an indirect connection of the resistor to the battery cell. The contact element can also be pre-assembled with the resistor, whereby corresponding resistors can be quickly and easily connected to the battery cell. The contact element can be connected to the respective battery terminal in a form-fitting, force-fitting and / or material-fitting manner; in particular, the contact element and the battery terminal can be welded together. This can take place before or after the resistor is mounted on the contact element.

[0010] A further advantageous embodiment of the battery according to the invention further provides that at least two battery cells are equipped with a respective resistor. This increases the flexibility in implementing charge equalization. Thus, the resistor provided for dissipating the excess charge can be selected depending on a wide variety of boundary conditions, for example, the respective current cell temperature. Thus, the resistor selected for carrying out charge equalization is the one connected to a battery cell with a particularly low temperature. The equalization module can have corresponding executive units, for example, a circuit in the form of a microcontroller, a microprocessor, or the like, which allow appropriate control of the resistors.

[0011] Preferably, all battery cells are equipped with a respective resistor, and the equalization module is further configured to dissipate the excess charge of a respective battery cell at precisely the resistor that is thermally conductively connected to the battery cell intended for charge equalization. In other words, each battery cell has its own resistor for charge equalization. Thus, the battery cell performing charge equalization also absorbs the heat dissipated by the respective resistor.

[0012] A further advantageous embodiment of the battery according to the invention further provides that the resistor is connected to the battery cell via a thermally conductive adhesive or a thermally conductive pad. This further improves heat transfer from the resistor to the battery cell. Such a thermally conductive adhesive or a thermally conductive pad is characterized in particular by a thermal conductivity that is on the order of magnitude of metals. The thermal conductivity is preferably greater than 10 W / (mK), particularly preferably greater than 50 W / (mK), most preferably greater than 100 W / (mK) or even greater. The resistor can also be soldered to the battery cell. The contact surface of the resistor on the battery cell should be as large as possible.

[0013] According to a further advantageous embodiment of the battery according to the invention, it is designed as a traction battery for a vehicle. The battery cells comprised by the battery according to the invention can particularly preferably be combined to form one or more battery modules. The individual battery modules can be connected in series and / or parallel in a targeted manner in order to set a desired capacity or voltage for the traction battery. These can be all common types of battery cells, such as round cells, prismatic cells, pouch cells, or the like. The battery cells of a traction battery are comparatively large and massive and are thus characterized by a particularly high thermal mass and thus capacity to absorb the dissipated heat of the resistors.

[0014] According to the invention, a vehicle comprises such a battery as described above. The vehicle can be any road vehicle such as a car, truck, van, bus, or the like. Generally, it could also be a rail vehicle, watercraft, or aircraft. The battery can be capable of active and / or passive cell balancing.

[0015] Further advantageous embodiments of the battery according to the invention also emerge from the exemplary embodiments which are described in more detail below with reference to the figures.

[0016] Showing: Fig. 1 is a schematic view of a battery cell provided with a resistor of a battery according to the invention; Fig. 2 is a schematic view of an alternative embodiment of the battery according to the invention; and Fig. 3 a schematic view of a further alternative embodiment of the battery according to the invention, in which the resistor is connected to the battery cell via a contact element.

[0017] A battery according to the invention comprises at least two rechargeable battery cells 1, wherein Fig. 1 only one battery cell 1 is shown. The battery according to the invention is therefore a secondary battery or an accumulator. The battery according to the invention further comprises a balancing module 2 for carrying out charge balancing of the battery cells 1. The balancing module 2 can also be referred to as a “balancer”. The balancing module 2 in turn comprises, in addition to corresponding connecting lines, cell monitoring electronics 6, for example in the form of a circuit board 8 provided with a microcontroller 7. The cell monitoring electronics 6 can also be referred to as “Cell Supervision Electronics” (CSE) or “Cell Supervising Circuit” (CSC). Particularly preferably, the battery according to the invention comprises a plurality of battery modules, each of which has its own cell monitoring electronics 6 (not shown). Each cell monitoring electronics 6 can be connected to a battery management system or integrated into such a system.

[0018] The cell monitoring electronics 6 or the equalization module 2 is capable of tapping the voltage across a respective battery cell 1 and thus monitoring it. If, particularly during a charging process of the battery according to the invention, it is determined that a corresponding cell voltage exceeds a specified threshold value, charge equalization can be started and the excess charge of a respective battery cell 1 can be dissipated at a respective resistor 3. According to the invention, the respective resistor 3 is not (locally) integrated into the cell monitoring electronics 6, but is attached to the respective battery cell 1 in a thermally conductive manner. This enables the heat dissipated by the resistor 3 to be introduced directly into the battery cell 1. The thermal mass of the battery cell 1 can thus be used to absorb the dissipation heat.The provision of separate cooling devices to dissipate the corresponding dissipation heat can therefore be dispensed with.

[0019] In Fig. 1, the resistor 3 is connected to the cell housing 4 of the battery cell 1 via a thermally conductive fastening material 9. Fig. 1 shows the provision of the resistor 3 on one end face of the battery cell 1. In general, it would also be possible to provide the resistor 3 on the casing of the battery cell 1. The Fig. 1 to 3 show battery cells 1 designed as round cells. In general, however, they could also be prismatic cells, pouch cells or the like.

[0020] According to the invention, at least one resistor 3 is provided on a battery cell 1. In general, several resistors 3, in particular resistors 3 assigned to different battery cells 1, could also be attached to one and the same battery cell 1 (not shown).

[0021] How Fig. 2 shows, the resistor 3 can be attached to a first battery cell 1 in a thermally conductive manner, but can be electrically connected to another battery cell 1. The Fig. The battery cells 1 shown in Figure 2 particularly preferably form a so-called cell assembly 10. One or more such cell assemblies 10 can form a battery module. The electrical interconnection of the battery cells 1 to one another is not shown.

[0022] Particularly advantageously, each battery cell 1 has a corresponding resistor 3 (not shown). The equalization module 2 can preferably be capable of dissipating the excess charge of a respective battery cell 1 at precisely the resistor 3 that is connected to the battery cell 1 intended for charge equalization. In other words, each battery cell 1 can thus have its "own" resistor 3.

[0023] Fig. 3 shows an alternative embodiment of the battery according to the invention. Here, the resistor 3 is connected to a contact element 5. The contact element 5 is in turn electrically connected to a battery terminal of the battery cell 1. In particular, the contact element 5 can be a so-called cell connector. The contact element 5 can, in particular, be welded to the battery terminal. Here, too, the resistor 3 can preferably be connected to the contact element 5 via a thermally conductive fastening material 9. Here, too, the contact element 5 could alternatively be attached to the casing of the battery cell 1.

[0024] The battery according to the invention makes it possible to utilize the thermal mass of a respective battery cell 1 to absorb the dissipation heat emitted by a respective resistor 3 during charge equalization. Thus, a separate cooling device for dissipating the dissipation heat can be dispensed with. This can reduce costs. Furthermore, the development and manufacturing effort for integrating the equalization module 2 or the cell monitoring electronics 6 into the battery 1 according to the invention is reduced. Since no corresponding cooling device can fail and local overheating is avoided by the spatially distributed arrangement of the resistors 3, the robustness of the battery according to the invention is increased.

Claims

[1] Battery, comprising at least two battery cells (1) and a balancing module (2) for carrying out a charge balancing of the battery cells (1), wherein the balancing module (2) is designed to dissipate the excess charge of at least one battery cell (1) at a resistor (3), characterized by that the resistor (3) is thermally conductively connected to one of the battery cells (1). [2] Battery according to claim 1, characterized by that the resistor (3) is thermally conductively connected to the cell housing (4) of the battery cell (1). [3] Battery according to claim 1, characterized by that the resistor (3) is thermally conductively connected to a contact element (5) of the battery cell (1), wherein the contact element (5) is electrically conductively connected to a battery pole of the battery cell (1). [4] Battery according to one of claims 1 to 3, characterized bythat at least two battery cells (1) are equipped with a respective resistor (3). [5] Battery according to claim 4, characterized by that all battery cells (1) are equipped with a respective resistor (3), and the equalization module (2) is further configured to dissipate the excess charge of a respective battery cell (1) at precisely the resistor (3) which is thermally conductively connected to the battery cell (1) provided for charge equalization. [6] Battery according to one of claims 1 to 5, characterized by that the resistor (3) is connected to the battery cell (1) via a thermally conductive adhesive or a thermal pad. [7] Battery according to one of claims 1 to 6, characterized by a version as a traction battery for a vehicle. [8] Vehicle, characterized by a battery according to claim 7.

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