Method for battery management of a battery with a charge state compensation system and battery management system

Abstract

The disclosure relates to a method for the battery management of a battery which comprises a plurality of battery cells and which is fitted with a battery management system for monitoring battery functionality and with a charge state compensation system, wherein the battery management system comprises a plurality of sensor control devices and a main control device, said control devices being connected with one another via a communication channel, and wherein the charge state compensation system has a number of charge state compensation resistors being put into operation via the sensor control devices for a charge state compensation of battery cells. The sensor control devices save information about performed charge state compensations in non-volatile memory. A computer program, a battery management system, a battery system and a motor vehicle, which are designed to carry out the method, are also described.

Claims

1. A method for battery management of a battery, the battery having a plurality of battery cells, a charge state balancing system, and a battery management system, the method comprising: monitoring operating parameters of the plurality of battery cells with the battery management system, the battery management system including a plurality of sensor control devices and a primary control device which are interconnected via a communication channel; operating, with the sensor control devices, a plurality of charge state balancing resistors of the charge state balancing system to balance charge states of the battery cells; and detecting, with the sensor control devices, and storing, in first nonvolatile memories of the sensor control devices, (i) a total number of temperature changes of each charge state balancing resistor in the plurality of charge state balancing resistors and (ii) a cumulative duration of charge state balancing performed with each charge state balancing resistor in the plurality of charge state balancing resistors; and resetting to zero, with the primary control device, (i) the total number of temperature changes of a respective charge state balancing resistor in the plurality of charge state balancing resistors and (ii) the cumulative duration of charge state balancing performed with a respective charge state balancing resistor in the plurality of charge state balancing resistors in response to a replacement of the respective charge state balancing resistor.

2. The method as claimed in claim 1, further comprising: ascertaining, with the primary control device, a charge state balancing requirement of the battery cells at an end of a driving cycle; communicating the charge state balancing requirement to the sensor control devices; and deactivating the primary control device after communicating the charge state balancing requirement and before operating the plurality of charge state balancing resistors of the charge state balancing system to balance charge states of the battery cells.

3. The method as claimed in claim 1, further comprising: transmitting, with the sensor control devices, (i) the total number of temperature changes of each charge state balancing resistor in the plurality of charge state balancing resistors and (ii) the cumulative duration of charge state balancing performed with each charge state balancing resistor in the plurality of charge state balancing resistors to the primary control device at an end of a driving cycle.

4. The method as claimed in claim 3, further comprising: storing, in a second nonvolatile memory of the primary control device, (i) the total number of temperature changes of each charge state balancing resistor in the plurality of charge state balancing resistors and (ii) the cumulative duration of charge state balancing performed with each charge state balancing resistor in the plurality of charge state balancing resistors.

5. A computer program for a battery management system of a battery, the battery having a plurality of battery cells and a charge state balancing system, the computer program configured to, when executed on a the battery management system: monitor operating parameters of the plurality of battery cells of the battery with the battery management system, the battery management system including a plurality of sensor control devices and a primary control device which are interconnected via a communication channel; operate, with the sensor control devices, a plurality of charge state balancing resistors of the charge state balancing system to balance charge states of the battery cells; detect, with the sensor control devices, and store, in first nonvolatile memories of the sensor control devices, (i) a total number of temperature changes of each charge state balancing resistor in the plurality of charge state balancing resistors and (ii) a cumulative duration of charge state balancing performed with each charge state balancing resistor in the plurality of charge state balancing resistors; and resetting to zero, with the primary control device, (i) the total number of temperature changes of a respective charge state balancing resistor in the plurality of charge state balancing resistors and (ii) the cumulative duration of charge state balancing performed with a respective charge state balancing resistor in the plurality of charge state balancing resistors in response to a replacement of the respective charge state balancing resistor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the present disclosure are depicted in the drawings and are described in greater detail in the following description.

(2) FIG. 1 shows a motor vehicle including a battery system,

(3) FIGS. 2A to 2D show histograms of sensor control devices, and

(4) FIGS. 3A and 3B show histograms of a primary control device.

(5) In the following description of the exemplary embodiments of the present disclosure, identical or similar components are depicted having identical or similar reference numerals; therefore, a repeated description of these components will be omitted in individual cases. The figures depict the subject matter of the disclosure only schematically.

DETAILED DESCRIPTION

(6) FIG. 1 shows an at least partially electrically driven motor vehicle 10 including a battery system 12.

(7) The motor vehicle 10 of FIG. 1 may be designed as a purely electrically driven vehicle or as a hybrid vehicle which additionally has an internal combustion engine. In addition, the motor vehicle 10 is equipped with an electric drive system 14, which drives the motor vehicle 10 via an electric motor (not shown) at least partially electrically.

(8) The electrical energy is provided by a battery 16. The battery 16 includes multiple battery cells 19 or accumulator cells, for example, lithium-ion cells having a voltage range from 2.8 V to 4.2 V. The battery cells 19 are combined in groups into battery modules 20 and connected in series and partially also in parallel, in order to achieve the required power and energy data via the battery 16.

(9) The battery 16 is part of a battery system 12, which in addition includes a battery management system. The battery management system includes a primary control device 18 and multiple sensor control devices 17 which are associated with the battery modules 20.

(10) The primary control device 18 and the sensor control devices 17 are connected via a communication channel 24, for example, an SPI (serial peripheral interface) bus or a CAN (controller area network) bus, via which cell monitoring units and module monitoring units (not shown) generally detect operating parameters such as voltages, current strengths, or temperatures of individual battery cells 19 or individual battery modules 20 as measured values and provide them to the primary control device 18 for monitoring and controlling the battery functionality. For communication, communication units 26, 28 are associated with the battery modules 20 and the primary control device 18.

(11) The battery 16, i.e., in the depicted exemplary embodiment, each battery module 20, has a charge state balancing system 22, which carries out resistive charge state balancing in the depicted exemplary embodiment. For this purpose, a switch 32 and a charge state balancing resistor 30 are associated with each battery cell 19, wherein the switch 32 may be actuated by the sensor control device 17. However, the present disclosure is not limited to this exemplary embodiment, but may be used in inductive or capacitive charge state balancing methods.

(12) Each sensor control device 17 includes the communication unit 26 and a charge state balancing control unit 33. The charge state balancing control unit 33 is configured to record information from implemented charge state balancing, in particular the number of temperature changes and the cumulative duration of the charge state balancing, and to store it in a first nonvolatile memory 34. The first nonvolatile memory 34 is, for example, an EEPROM (electrically erasable programmable read-only memory), in which the information is permanently stored.

(13) The primary control device 18 includes a second nonvolatile memory 36, in which the information about implemented charge state balancing which is ascertained and stored by the sensor control devices 17 is permanently stored.

(14) FIGS. 2A to 2D show histograms 38, FIG. 2A and FIG. 2B being associated with a first sensor control device 17, and FIG. 2C and FIG. 2D being associated with a second sensor control device 17. The histograms represent the information stored by the sensor control devices 17 from implemented charge state balancing. The information depicted in FIGS. 2A to 2D may be read out of the first nonvolatile memories 34 of the sensor control devices 17 and analyzed.

(15) The histogram 38 in FIG. 2A represents a measured number of temperature changes for each charge state balancing resistor 30. For this purpose, frequency values 40 are plotted above identifiers 42 of the charge state balancing resistors 30.

(16) FIG. 2B depicts the cumulative duration of charge state balancing for the charge state balancing resistors 30. For this purpose, time period values 44 are plotted above the identifiers 42 of the charge state balancing resistors 30.

(17) FIG. 2C and FIG. 2D depict the corresponding information about the number of temperature changes and the cumulative duration of the charge state balancing for charge state balancing resistors 30 of the second sensor control device 17.

(18) FIG. 3A and FIG. 3B depict information about the number of temperature changes and the cumulative duration of the charge state balancing of all charge state balancing resistors 30 of the battery 16. The identifiers 42 of the individual charge state balancing resistors 30 are unambiguously assigned within the battery 16, The information in the primary control device 18 forms overall histograms 46, which may be read out of the second nonvolatile memory 36 of the primary control device 18 and analyzed.

(19) In practice, a method may be implemented as follows:

(20) At the beginning of the driving cycle, the primary control device 18 powers up. The information about the charge state balancing resistors 30 in the primary control device 18 originates from the penultimate driving cycle during normal operation, since the information about the charging state balancing following the last driving cycle is only transmitted by the sensor control devices 17 following the driving cycle.

(21) At the end of the driving cycle, the primary control device 18 requests the current state of the usage information of the charge state balancing resistors 30 from the sensor control devices 17. Subsequently, the primary control device 18 sends the command for carrying out the charge state balancing to the sensor control devices 17 and deactivates itself. If the primary control device 18 is deactivated, the charge state balancing is carried out by the sensor control devices 17 autonomously.

(22) At the end of the next driving cycle, the primary control device 18 in turn requests the current state of the usage information of the charge state balancing resistors 30 from the sensor control devices 17. In this case, as after the previous driving cycle, the information is stored in the first nonvolatile memory of the sensor control devices 17 and transmitted thereafter. Subsequently, the primary control device 18 in turn sends the command for carrying out the charge state balancing to the sensor control devices 17 and deactivates itself. If the primary control device 18 is deactivated, the request is carried out autonomously.

(23) The present disclosure is not limited to the exemplary embodiments described here and the aspects emphasized therein. Rather, within the framework indicated by the disclosure, a plurality of modifications is possible, which are within the capabilities of those skilled in the art.