Battery management procedures

Abstract

The present invention relates to a method for managing a battery pack, particularly in a power tool or an electric vehicle, with a plurality of battery cells connected in series. The method comprises the steps of receiving an external voltage signal and adjusting a cell tap of a defined number of battery cells based on the received external voltage signal.

Description

State of the art

[0001] The present invention relates to a method for battery management of a battery pack and to an electric vehicle or a power tool with a battery management system which is configured to carry out the battery management method.

[0002] Current technology often involves mobile electronic assemblies that comprise different systems that must be adapted to the respective battery voltage of the assembly. Connecting system components of different voltage classes may be impossible or cause damage. For example, it is not always possible to charge a 36 V battery with a 48 V charger.

[0003] It would be desirable to have a method and a device that enables the connection of different system components in a simple and cost-effective manner. Disclosure of the invention

[0004] The method according to the invention with the features of claim 1 and the electric vehicle or power tool with the features of claim 12 have the advantage that system components of different voltage classes can be easily connected to one another.

[0005] This is achieved according to the invention by a method for battery management of a battery pack with a plurality of battery cells connected in series.

[0006] The method is used in particular for battery management of battery packs in power tools or electric vehicles. The method receives an external voltage signal in one step. Subsequently, a cell tap from a defined number of battery cells is adjusted based on the received external voltage signal. An external voltage signal preferably comprises voltage information that does not originate from the battery pack. The output voltage of the battery pack is preferably the sum of the tapped individual cell voltages of the series-connected battery cells. By tapping a defined number of battery cells, the battery pack can thus be flexibly adapted to the requirements of connected system components. Furthermore, interfaces between the battery pack and connected components can be standardized.Familiar interfaces can make handling easier for the customer and during assembly.

[0007] The subclaims show preferred developments of the invention.

[0008] Preferably, the cell tap adjusts the battery pack's output voltage. This allows the battery pack's output voltage to be specifically adapted to the connected system components, ensuring the functionality of the connected system components and preventing damage.

[0009] The method preferably includes a further step in which a test voltage is output from the battery pack to obtain an external voltage signal from a component electrically connected to the battery pack. The test voltage is preferably significantly lower than the minimum dielectric strength of a possible connected component. This enables a safe system start of the battery pack.

[0010] Further preferably, the external voltage signal comprises a dielectric strength and / or a required supply voltage of the electrical component.

[0011] Particularly preferably, the cell tap is adjusted so that the output voltage is less than or equal to the dielectric strength of the connected electrical component. This can prevent damage to a component connected to the battery pack due to voltage breakdown caused by an excessively high output voltage.

[0012] If it is not possible to adjust the output voltage through cell tapping such that the battery pack's output voltage is lower than the dielectric strength of the connected electrical component, the user is preferably given a warning that the battery pack is incompatible with the connected electrical component. This warning is preferably provided via a human-machine interface (HMI).

[0013] Furthermore, the cell tap is preferably adjusted so that the output voltage is greater than or equal to the required supply voltage of the connected electrical component. This ensures the proper functioning of all electrical components connected to the battery pack.

[0014] The external voltage signal preferably comprises a charging voltage. Particularly preferably, the external voltage signal originates from a charger connected to the battery pack. The external voltage signal can have an electrical voltage equal to the charging voltage or include information about the charging voltage. This can enable the battery pack to be adapted to the charger.

[0015] More preferably, the cell tap is adjusted to the charging voltage. In particular, enough battery cells are tapped so that the end-of-charge voltage of the battery cell is not exceeded. This ensures that the battery pack is charged efficiently and safely. For example, if the battery pack has a end-of-charge voltage of 48 V, but the charging voltage is only 36 V, the cell tap can be adjusted so that the tapped battery cells have a end-of-charge voltage of 36 V. Alternatively, the charging voltage can be increased using a voltage converter to fully charge the battery pack.

[0016] Particularly preferably, the charging voltage is converted down to a battery voltage if the charging voltage is higher than the battery voltage. This prevents damage or overcharging of the battery pack. The battery voltage is preferably a final charging voltage of the tapped battery cells. Alternatively, the battery voltage can be another voltage criterion for the charging process of the battery cells.

[0017] Preferably, the cell tap is adjusted to the battery cell charge level. This is especially true if, due to the cell tap, not all battery cells in the battery pack are charged simultaneously. By taking the battery cell charge level into account, the cell tap can be adjusted so that the battery pack is charged evenly.

[0018] According to a further preferred embodiment of the invention, each battery cell can be tapped individually or in combination with other battery cells. This allows for maximum flexibility in cell tapping.

[0019] Furthermore, the invention relates to an electric vehicle or a power tool comprising a battery pack, an electrical component, and a battery management system. The battery management system is configured to carry out the method described above. The electric vehicle is preferably an electric bicycle. This enables high compatibility of the battery pack with various electrical components.

[0020] Preferably, the electric vehicle or power tool comprises a frame, with the battery pack distributed across at least two parts of the frame. Based on the method described above, the battery cells of the individual battery packs can be tapped independently of one another. Short description of the drawings

[0021] Embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing: Fig. 1 a schematic flow diagram of a method for battery management of a battery pack according to a first embodiment, Fig. 2 a schematic flow diagram of the method according to a second embodiment, Fig. 3 a schematic representation of an electric vehicle with an electrically connected component and a battery management system for carrying out a method according to the first and second embodiments, and Fig. 4 a schematic representation of the battery pack with the electrically connected component and the battery management system for carrying out a method according to the first and second embodiments. Embodiments of the invention

[0022] The following is based on the Fig. 1 to 4, an apparatus and a method according to a first and second preferred embodiment of the invention are described in detail.

[0023] Fig. 1 shows a first embodiment of a method for battery management of a battery pack 1 with a plurality of battery cells 10 connected in series.

[0024] In a first step S1, a test voltage is output to obtain an external voltage signal 20 from a component 2 electrically connected to the battery pack 1. The test voltage is lower than the dielectric strength of the electrically connected component 2, so that it is not damaged. If the dielectric strength of the electrically connected component 2 is unknown, the test voltage is preferably significantly lower than an expected dielectric strength of the connected component 2.

[0025] Preferably, the battery pack 1 is electrically connected to a plurality of components 2. The test voltage is applied simultaneously or sequentially to the individual electrically connected components 2.

[0026] The test voltage and a resulting test current preferably supply the connected electrical component 2 with enough electrical energy to enable it to output an external voltage signal 20.

[0027] The test voltage is preferably generated by means of a voltage converter and / or by an adapted cell tap from the battery cells 10 of the battery pack 1.

[0028] In a second step S2, the external voltage signal 20 of the at least one electrically connected component 2 is received by a battery management system 5.

[0029] Based on the received external voltage signal 20, the cell tap of a defined number of battery cells 10 is adjusted in a third step S3. Thus, the output voltage of the battery pack 1 can be adjusted such that it is greater than or equal to a required supply voltage and less than or equal to the dielectric strength of the electrically connected component 2.

[0030] The battery pack 1 comprises at least two battery cells 10 connected in series. Additionally, the battery pack 1 can also have battery cells 10 connected in parallel. Preferably, all battery cells 10 connected in series can be tapped individually. By tapping several battery cells 10 together, their voltage can be added together. The battery is preferably tapped using electrical switches 14, which are controlled by the battery management system 5.

[0031] Preferably, steps S1 to S3 are carried out directly one after the other.

[0032] Fig. 2 shows a second embodiment of the method for battery management of a battery pack 1.

[0033] In the second embodiment of the method according to the invention, the external voltage signal 20 is received in step S2, which comprises information about a charging voltage.

[0034] The external voltage signal 20 in the second embodiment preferably originates from a charger with a defined charging voltage. The external voltage signal 20 with the charging voltage is preferably sent by the charger before the charging process.

[0035] Subsequently, in step S3, the cell tap of a defined number of battery cells is adjusted to the charging voltage based on the external voltage signal 20.

[0036] The cell tap is preferably selected such that the charging voltage drop in a battery cell 10 does not exceed its maximum charging voltage, also called the end-of-charge voltage. Furthermore, the cell tap is preferably selected such that the battery pack 1 can be charged as quickly and evenly as possible.

[0037] During the charging process, the cell tap is preferably adjusted based on the state of charge of the individual battery cells 10.

[0038] Fig. Figure 3 schematically shows an electric vehicle 3 in the form of an electric bicycle with a frame 4. In the frame 4, a first battery pack 11 and a second battery pack 12 are arranged, which are electrically connected to a component 2. The component 2 is in the embodiment in Fig. 3, for example, an electric drive. Furthermore, a battery management system 5 is arranged in the frame 4 of the electric bicycle, which is configured to carry out the method according to the first and second embodiments.

[0039] The first battery pack 11 and the second battery pack 12 are in Fig. 3 are arranged in two different frame tubes and electrically connected to each other via a cable. Thus, multiple battery packs 1 can be easily integrated into the electric vehicle 3. For example, the first battery pack 11 can be arranged in the top tube and the second battery pack 12 in the seat tube.

[0040] The battery management system 5 is in Fig. 3 is arranged in the down tube of the frame 4 and is electrically connected to the electrical component 2 and the second battery pack 12 via a cable. Thus, the battery management system 5 is configured to receive an external voltage signal 20 from the electrical component 2 and to adjust the cell tap to battery cells 10 of the first battery pack 11 and / or the second battery pack 12 accordingly.

[0041] The electrical component 2 is in Fig. 3 is depicted as an electric motor. Other electrical components 2 may include, for example, a bicycle light or a bicycle computer.

[0042] Fig. 4 shows a schematic representation of the battery pack 1 with the battery management system 5 and the connected electrical component 2.

[0043] The battery pack 1 comprises a first battery cell 11, a second battery cell 12, and a third battery cell 13, which are connected in series. Each battery cell 10 is connected to the electrical component 2 via an electrical switch 14. A voltage converter 6 is also arranged between the battery cells 10 and the electrical component 2. The voltage converter 6 can also be connected to or disconnected from the electrical component 2 via an electrical switch 14.

[0044] The electrical switches 14 and the voltage converter 6 can be arranged both inside the battery pack 1 and outside the battery pack 1. The battery management system 5 can also be arranged either inside or outside the battery pack 1.

[0045] The battery management system 5 can, for example, control the third battery cell 13 and the voltage converter 16 by controlling the electrical switches 14 to send a test voltage to the electrically connected component 2. The electrical component 2 then sends a voltage signal 20 to the battery management system 5 to communicate, for example, its dielectric strength and / or required supply voltage.

[0046] The battery management system 5 can then calculate the required output voltage of the battery pack 1 and the necessary cell tap. If the maximum output voltage of the battery pack 1 is, for example, 30 V, but the required supply voltage of the electrical component 2 is 20 V, the output voltage of the battery pack 1 can be reduced to 20 V by tapping the first battery cell 11 and the second battery cell 12, as shown in Fig. 4 by the closed electrical switch 14 between the second battery cell 12 and the third battery cell 13.

[0047] The electrical component 2 can also be a charger that transmits the charging voltage to the battery management system 5 as a voltage signal 20. Based on the charging voltage, the battery management system 50 can adjust the cell tap of the battery cells 10 in the battery pack 1 to ensure a fast, efficient, and safe charging process.

[0048] If the charging voltage is higher than the maximum battery voltage of battery pack 1, all battery cells 10 are tapped, and the voltage converter 6 is switched on to convert the charging voltage down to the battery voltage. The battery voltage of battery pack 1 is preferably also its final charging voltage.

[0049] If the charging voltage is equal to the maximum battery voltage, all battery cells 10 of the battery pack 1 are tapped for the charging process without switching on the voltage converter 6.

[0050] If the charging voltage is lower than the maximum battery voltage, individual battery cells 10 of the battery pack 1 can be tapped. For example, as in Fig. 4, at a charging voltage of 20 V and a battery voltage of the battery pack 1 of 30 V, the first battery cell 11 and the second battery cell 12 are tapped by the battery management system 5 closing the electrical switch 14 between the second battery cell 12 and the third battery cell 13.

[0051] To ensure a uniform charge level of the battery cells 10 in the battery pack 1, the cell tapping can be adjusted during the charging process. For example, the first battery cell 11 and the third battery cell 13, the second battery cell 12 and the third battery cell 13, or the first battery cell 11 and the second battery cell 12 can be tapped alternately.

Claims

Method for battery management of a battery pack (1), in particular in a power tool or an electric vehicle, with a plurality of battery cells (10) connected in series, comprising the steps of:- receiving (S2) an external voltage signal (20), and- adjusting (S3) a cell tap of a defined number of battery cells (10) based on the received external voltage signal (20). Method according to claim 1, wherein the cell tap adjusts an output voltage of the battery pack (1). Method according to claim 2, comprising the step of: outputting (S1) a test voltage to obtain the external voltage signal (20) from a component (2) electrically connected to the battery pack (1). Method according to claim 3, wherein the external voltage signal (20) comprises a dielectric strength and / or a required supply voltage of the electrical component (2). Method according to claim 4, wherein the cell tap is adjusted such that the output voltage is less than or equal to the dielectric strength of the connected electrical component (2). Method according to claim 4 or 5, wherein the cell tap is adjusted such that the output voltage is greater than or equal to the required supply voltage of the connected electrical component (2). Method according to claim 1, wherein the external voltage signal (20) comprises a charging voltage. Method according to claim 7, wherein the cell tap is adapted to the charging voltage. Method according to claim 7 or 8, wherein the charging voltage is converted down to a battery voltage when the charging voltage is greater than the battery voltage. Method according to one of claims 7 to 9, wherein the cell tap is adapted to a state of charge of the battery cells (10). Method according to one of the preceding claims, wherein each battery cell (10) can be tapped individually or in combination with further battery cells (10). Electric vehicle or power tool, comprising a battery pack, an electrical component (2) and a battery management system (5) which is configured to carry out a method according to one of claims 1 to 11. Electric vehicle or power tool according to claim 12, comprising a frame (4), wherein the battery pack (1) is distributed in at least two parts of the frame (4).

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