Battery for a motor vehicle and method for operating a battery

Abstract

A battery for a motor vehicle, having multiple battery cells which include respective battery cell housings with electric terminals via which the battery cells are electrically connected to one another. In the battery cell housings, in each case a cell branch connecting the terminals, with a galvanic cell, is arranged, and in each case several of the battery cells are connected to one another in parallel connection to form respective cell blocks. Each cell branch includes a switching element for opening and closing the cell branch; the battery has a control device which is configured in order to actuate the switching elements of the cell branches for opening or closing the switching elements as a function of a performance requirement of an electric drive of the motor vehicle.

Claims

1. A battery for a motor vehicle, comprising: a plurality of cell blocks, each cell block formed by connecting a plurality of battery cells in parallel, wherein each battery cell of each plurality of battery cells comprises a battery cell housing with electric terminals by which each plurality of battery cells are electrically connected to one another; wherein each of the battery cell housings contain therein a galvanic cell and a cell branch which connects the galvanic cell to the electric terminals; wherein each cell branch has a switching element for opening and closing the cell branch; wherein the battery has a control device which is configured to actuate the switching elements of the cell branches as a function of a performance requirement of an electric drive of the motor vehicle; wherein, for each of the plurality of cell blocks, in at least one of the plurality of battery cells, a bypass branch is arranged in the battery cell housing for bridging the galvanic cell, the bypass branch comprising a bridging switching element for opening and closing the bypass branch; and wherein, for bridging all of the plurality of cell blocks, for each of the plurality of cell blocks, the control device is configured to open all the switching elements and to close the at least one bridging switching element.

2. The battery according to claim 1, wherein the control device is configured to actuate the switching elements of the cell branches as a function of a respective temperature of the pluralities of battery cells.

3. The battery according to claim 1, wherein the control device is configured to actuate the switching elements of the cell branches in such a manner that, in adjacent battery cells of different cell blocks, the switching elements are switched oppositely.

4. The battery according to claim 1, wherein the control device is configured to actuate the switching elements of the cell branches as a function of a respective state of charge of the pluralities of battery cells.

5. The battery according to claim 1, wherein the control device is configured to actuate the switching elements of the cell branches as a function of a state of health of the pluralities of battery cells.

6. The battery according to claim 1, wherein the bypass branch is provided in the battery cell housing of each and every battery cell, wherein the control device is configured, for bridging all of the plurality of cell blocks, for each of the plurality of cell blocks, to open all the switching elements and to close all of the bridging switching elements.

7. The battery according to claim 1, wherein the each and every battery cell further comprises at least one sensor for the acquisition of at least one operating parameter of the battery cell, which is designed to transmit data concerning the operating parameter to the control device.

8. A method for operating a battery according to claim 1, comprising: the control device of the battery, as a function of the performance requirement of the electric drive of the motor vehicle, actuates the switching elements of the cell branches for opening or closing the switching elements.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) Additional features, advantages and details of the invention result from the following description of preferred embodiment examples as well as in reference to the drawing. The features and combinations of features mentioned above in the description and the features and combination of features mentioned below in the description of the figures and/or shown in the figures alone can be used not only in the respective indicated combination but also in other combinations or alone without going beyond the scope of the invention.

(2) The drawing shows in:

(3) FIG. 1 a diagrammatic representation of a motor vehicle with a battery for the energy supply of an electric drive of the motor vehicle, wherein the battery comprises multiple cell blocks and a control device which is configured to switch on or bypass respective battery cells, not represented, of the cell blocks as a function of a performance requirement of the electric drive;

(4) FIG. 2 a diagrammatic representation of a first embodiment of the battery, wherein multiple series-connected cell blocks are represented, which comprise multiple parallel-connected battery cells in which in each case a switching element for interrupting a current flow at the cell level is integrated; and

(5) FIG. 3 a diagrammatic representation of another embodiment of the battery, wherein this embodiment differs from the embodiment shown in FIG. 2 in that each of the battery cells comprises another bypass branch.

(6) In the figures, identical or functionally equivalent elements are provided with identical reference numerals.

DETAILED DESCRIPTION

(7) A motor vehicle 10 with an electric drive 12 is shown in a diagrammatic representation in FIG. 1. The motor vehicle 10 comprises a battery 14 which is used for the energy supply of the electric drive 12. The battery 14 comprises multiple diagrammatically indicated cell blocks 16 and a control device 18 which is configured to bypass and switch on individual battery cells, not represented here, of the respective cell blocks 16 depending on the performance requirement of the electric drive 12.

(8) In FIG. 2, a first embodiment of the battery 14 is represented diagrammatically. Here, several of the cell blocks 16 are series-connected, so that the individual voltages of the cell blocks 16 add up to a total voltage between a positive pole 20 and a negative pole 22 at the level of the battery overall.

(9) The individual cell blocks 16 comprise multiple battery cells 24 connected in parallel to one another. The respective battery cells 24 comprise respective battery cell housings 26 with electric terminals 28, 30 via which the individual battery cells 24 are electrically connected to one another. In each case, in the battery cell housings 26, a cell branch 32 connecting the terminals 28, 30, with a galvanic cell 34, is arranged. Each of the cell branches 32 in addition comprises a switching element 36 for opening and closing the respective cell branch 32, so that a current flow via or through the galvanic cell 34 can be enabled or prevented.

(10) The control device 18 mentioned in connection with FIG. 1 is configured to actuate the individual switching elements 36 of the cell branches 32 for opening or closing the switching elements 36 as a function of a respective performance requirement of the electric drive 12 of the motor vehicle 10. This can occur, for example, in a centralized manner by the control device 18, wherein this can also occur, for example, in a decentralized manner by individual microcontrollers, not represented here, which belong to the control device 18.

(11) The control device 18 can thus open for each cell block 16 all the switching elements 36 except for one as a function of the performance requirement of electric motor 12, so that, in the case of the lowest performance requirement and thus the lowest power provision by the battery 14, in each case only one of the galvanic cells 34, which can be, for example, lithium ion cells or also fuel cells, is used for the energy provision. Due to the series connection of the individual cell blocks 16 it is necessary that for each cell block 16 at least one of the switching elements 36 is thus closed, so that a current flow from the positive pole 20 to the negative pole 22 of the overall battery 14 can occur. Naturally, depending on the performance requirement of the electric drive 12, several of the switching elements 36 can be closed. For example, if a driver of the motor vehicle 10 fully depresses a gas pedal, then all the switching elements 36 can be closed, so that the maximum power can be provided by means of the battery 14.

(12) In addition, the control device 18 can also actuate the respective switching elements 36 inside the cell for opening or closing as a function of a respective temperature of the individual battery cells 24. In view of the actual performance requirement of the electric motor 12, a respective temperature at the cell level is thus also taken into consideration in this manner, so that, for example, hot spots within the battery 14 can be avoided, in that the individual battery cells 24 are used alternatingly for the energy supply, so that the individual battery cells 24 during the use in the motor vehicle 10 can also cool off again sufficiently before they are used again for the energy supply.

(13) Thus, the control device 18 can actuate, for example, the switching elements 36 of the cell branches 32 for opening or closing the switching elements 36 in such a manner that, in adjacent battery cells 24 of different cell blocks 16, the respective switching elements 36 are always switched oppositely. In this manner, in immediately adjacent battery cells 24 of different cell blocks 16, current is prevented from flowing simultaneously through the two adjacent battery cells 24. Thereby, an unfavorable thermal heating up or mutually thermal influencing of adjacent battery cells 24 in different cell blocks 16 is prevented.

(14) In addition, the control device 18 can also take into consideration respective states of charge of the individual battery cells 24 and actuate the respective switching elements 36 as a function thereof in such a manner that the individual battery cells 24 are discharged as uniformly as possible. Furthermore, the control device 18 can also take into consideration a respective state of health of the individual battery cells 24 in the actuation of the switching elements 36. In this manner, the control device 18 can ensure that the individual batteries 24 age at least substantially uniformly, which has a positive effect on the performance capability and the useful life of the entire battery 14.

(15) In FIG. 3, another possible embodiment of the battery 14 is represented diagrammatically. The embodiment shown here differs from the embodiment shown in FIG. 2 in that, in addition, a bypass branch 38 for bypassing the respective galvanic cells 34 is arranged in all the battery cell housings 26. Each of the bypass branches 38 comprises a bypass switching element 40 for opening and closing the bypass branch 38. In order to bypass all the cell blocks 16, the control device 18 is configured to open, for each cell block 16, all the switching elements 36 and to close at least one of the bypass switching elements 40. In the embodiment of the battery 14 shown in FIG. 3, it is also possible, without problem, to bypass all the cell blocks 16 by corresponding actuation of the switching elements 36 and of the bypass switching elements 40 in such a manner that, in the cell blocks 16 in question, no current flow via the galvanic cells 34 occurs. This is possible without problem due to said bypass branches 38. Thus, if, for example, one of the cell blocks 16 is to be bypassed completely, then the control device 18 actuates the switching elements 36 in the cell block 16 in question in such a manner that they are all opened, wherein, in addition, the control device 18 actuates, for example, all the bypass switching elements 40 in such a manner that they are closed. In this case, a current distributed over all the battery cells 24 of the cell block 16 to be bypassed can flow via the respective bypass branches 38.

(16) By bypassing individual cell blocks 16, for example, in an eco operating mode of the motor vehicle 10 in question, all the cell blocks 16 can thus be switched off, as a result of which the voltage level of the battery 14 is lowered in accordance with the cell blocks 16 that are switched off. Thus, at the cell block level, all the battery cells 24 located in the cell block 16 in question can be spared in a simple manner.

(17) If, in the meantime, it has then become necessary to provide, for example, the full power by means of the battery 14, then the control device 18, can close all the switching elements 36 in all the cell blocks 16 and open all the bypass switching elements 40, as a result of which the maximum power can be provided by means of the battery 14.

(18) In the embodiment of the battery 14 shown in FIG. 3 as well, it is possible, in addition to the actual performance requirement of the electric drive 12, also to take into consideration respective temperatures, states of charge, aging states or states of health at the cell level. The embodiments of the battery 14 shown in FIG. 2 and in FIG. 3 can both comprise at the cell level one or more sensors which can measure a wide variety of operating parameters of the respective battery cells 24, such as, for example, voltages, currents, internal cell pressures and the like, and transmit associated data to the control device 18.

(19) Thus, knowing the respective operating parameters of the battery cells 24, the control device 18 can switch the respective battery cells 24 on or off for the respective energy provision. Overall, at the cell level, the different embodiments of the battery 14 thus offer the possibility of reacting in a particularly flexible manner to respective performance requirements of the electric drive 12, on the one hand, and of switching the individual battery cells 24 on and off at the cell level, on the other hand, so that the individual battery cells 24 experience a particularly optimal temperature management, uniform discharging and uniform aging.