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DE-102024132690-A1 - DEVICE AND METHOD FOR MONITORING A BATTERY SYSTEM AND MOTOR VEHICLE

DE102024132690A1DE 102024132690 A1DE102024132690 A1DE 102024132690A1DE-102024132690-A1

Abstract

A method for monitoring a battery system comprising several battery elements connected in series exhibits: Recording a voltage assigned to each of the battery elements; Comparing a first voltage of the measured voltages with at least two other measured voltages or with a predetermined voltage to determine whether there is an anomaly in the battery system; Recording the total voltage assigned to each pair of adjacent battery elements when an anomaly in the battery system has been determined; Calculating the magnitude of a difference between a first sum voltage assigned to a first pair of adjacent battery cells and a second sum voltage assigned to a second pair of adjacent battery cells, wherein the first of the detected voltages is assigned to a battery cell of the first pair of adjacent battery cells; Determine that a battery element of the first pair is defective if the amount of the difference is greater than a threshold, or Determine that a fault exists in the voltage sensing device if the magnitude of the difference is less than another threshold.

Inventors

  • Julian Wiesmeier
  • Dominik Gruber
  • Jasmin Kalb
  • Christian Maerzinger

Assignees

  • BAYERISCHE MOTOREN WERKE AKTIENGESELLSCHAFT

Dates

Publication Date
20260513
Application Date
20241108

Claims (9)

  1. Method for monitoring a battery system (500) comprising a battery having several battery cells (10-1, ..., 10-7) connected in series, and a voltage sensing device ( V1 , ..., V7 ) configured to detect a voltage ( U1 , ..., U7 ) associated with each of the battery cells (10-1, ..., 10-7) and a total voltage ( U1 + U2 , U2 + U3 , ..., U6 + U7 ) associated with each pair (P1, ..., P6) of adjacent battery cells (10-1, ..., 10-7), wherein the method comprises: operating the voltage sensing device ( V1 , ..., V7 ) to detect a voltage ( U1 , ..., U7 ) associated with each of the battery cells (10-1, ..., 10-7); Comparing a first voltage (U 1 ) of the recorded respective voltages (U 1 , ..., U 7 ) assigned to a respective of the battery elements (10-1, ..., 10-7) with at least two other recorded voltages of the respective voltages (U 1 , ..., U 7 ) assigned to a respective of the battery elements (10-1, ..., 10-7) or with a predetermined voltage based on a predetermined criterion, in order to determine whether or not there is an anomaly in the battery system (500); Operating the voltage detection device ( V1 , ..., V7 ) to detect a total voltage ( U1 + U2 , U2 + U3 , ..., U6 + U7 ) assigned to a respective pair ( P1 , ..., P6 ) of adjacent battery elements ( 10-1 , ..., 10-7 ) when it has been determined that an anomaly of the battery system (500) is present; Forming a magnitude of a difference between a first sum voltage (U 1 + U 2 ) assigned to a first pair (P1) of adjacent battery elements (10-1, 10-2) and a second sum voltage (U 2 + U 3 ) assigned to a second pair (P2) of adjacent battery elements (10-2, 10-3), wherein the first of the detected voltages is assigned to a battery element (10-1, 10-2) of the first pair (P1) of adjacent battery elements (10-1, ..., 10-7); Determine that a battery element (10-1, 10-2) of the first pair (P1) of battery elements (10-1, ..., 10-7) is defective if the magnitude of the difference is greater than a first predetermined threshold, or determine that there is a fault in the voltage sensing device (V 1 , ..., V 7 ) if the magnitude of the difference is less than a second predetermined threshold.
  2. Procedure according to Claim 1 , wherein a respective amount of a respective difference between the first total voltage (U 1 + U 2 ) assigned to the first pair (P1) of adjacent battery elements (10-1, 10-2) and a respective second total voltage (U 2 + U 3 , ..., P6) assigned to a respective second pair (P2, ..., P6) of adjacent battery elements (10-2, 10-3 ; ...; 10-6 , 10-7 ) is formed when it has been determined that an anomaly of the battery system (500) is present, wherein the first of the detected voltages is assigned to a battery element (10-1, 10-2) of the first pair (P1) of adjacent battery elements (10-1, ..., 10-7); and it is determined that a battery cell (10-1, 10-2) of the first pair (P1) of adjacent battery cells (10-1, ..., 10-7) is defective if all amounts of the respective differences or a mean The value of all the amounts of the respective differences is greater than the first specified threshold, or it is determined that there is a fault in the voltage detection device (V 1 , ..., V 7 ) if all the amounts of the respective differences or an average of all the amounts of the respective differences are less than the second specified threshold.
  3. Method according to one of the preceding claims, wherein the anomaly is determined to be present if a respective amount of a respective difference between the first voltage (U 1 ) and each of the at least two other detected voltages is greater than a third predetermined threshold or an amount of a difference between the first voltage (U 1 ) and the predetermined voltage is greater than a fourth predetermined threshold.
  4. A method according to one of the preceding claims, wherein a comparison of a first of the detected respective voltages (U 1 , ..., U 7 ) associated with a respective of the battery elements (10-1, 10-7) with at least two detected other voltages (U 1 , ..., U 7 ) associated with a respective of the battery elements (10-1, ..., 10-7) or a predetermined voltage is carried out on the basis of a predetermined criterion for each of the respective voltages (U 1 , ..., U 7 ) associated with a respective of the battery elements (10-1, ..., 10-7) in order to determine whether the anomaly of the battery system (500) is present or not.
  5. Method according to one of the preceding claims, wherein, when it is determined that a fault of the voltage detection device (V 1 , ..., V 7 ) is present, a voltage is assigned to each battery element (10-1, 10-2) of the first pair (P1) of adjacent battery elements which is equal to half of the first sum voltage (U 1 + U 2 ).
  6. Method according to one of the preceding claims, wherein the battery element (10-1, ..., 10-7) comprises one battery cell or several battery cells connected in parallel and/or in series.
  7. Method according to one of the preceding claims, wherein the battery system (500) comprises a voltage sensing device (V G ) which is configured to detect a total voltage of the several battery elements (10-1, ..., 10-7) connected in series.
  8. Device (200) for monitoring a battery system (500) which is configured to perform a method according to any of the preceding claims.
  9. motor vehicle (600) comprising a device (200) according to Claim 8 .

Description

The present invention relates to a device and a method for monitoring a battery system and to a motor vehicle which incorporates the device. The present invention relates in particular to a device and a method for monitoring a battery system which is designed as a high-voltage storage device and can be used in motor vehicles to supply an electric drive motor of the motor vehicle with electrical energy. Such battery systems typically have several battery cells connected in series, whose voltages must remain within a predetermined range for safety reasons. A voltage monitoring device is provided to monitor the battery system. This device is designed to detect the voltage of each individual battery cell. If any of the detected voltages fall outside the predetermined range, a control unit issues a warning or, if necessary after a predetermined period, shuts down the battery system, thus preventing the vehicle from being supplied with propulsion energy. Typically, measuring leads are used to measure the voltages of the battery cells, with each cell connected between the cells. This means that if one measuring lead fails, the voltages of two adjacent battery cells may not be measured, or only inaccurately. Furthermore, if one of the measured voltages is outside the specified range, it cannot be distinguished whether the battery element is defective and the measuring lead is not, or the battery element is not defective and the measuring lead is defective, or both the battery element and the measuring lead are defective. One objective of the present invention is to improve the monitoring of a battery system. This problem is solved by the features of the independent patent claims. Further preferred embodiments of the invention are the subject of the dependent patent claims. According to a first aspect of the present invention, a method for monitoring a battery system comprising a battery having several battery elements connected in series and a voltage detection device configured to detect a respective voltage associated with each of the battery elements and a respective sum voltage associated with each pair of adjacent battery elements comprises: Operating the voltage detection device to detect a respective voltage assigned to each of the battery elements; Comparing a first voltage of the recorded respective voltages assigned to each of the battery elements with at least two other recorded voltages of the respective voltages assigned to each of the battery elements or with a predetermined voltage based on a predetermined criterion, in order to determine whether an anomaly of the battery system is present or not; Operating the voltage detection device to detect a total voltage assigned to each pair of adjacent battery elements when an anomaly in the battery system has been determined; Calculating the magnitude of a difference between a first sum voltage assigned to a first pair of adjacent battery cells and a second sum voltage assigned to a second pair of adjacent battery cells, wherein the first of the detected voltages is assigned to a battery cell of the first pair of adjacent battery cells; Determine that a battery cell of the first pair of battery cells is defective if the amount of the difference is greater than a first predetermined threshold, or Determine that a fault exists in the voltage detection device if the magnitude of the difference is less than a second predetermined threshold. In some designs, this allows the battery system, and thus a motor vehicle equipped with it, to continue operating advantageously if a fault in the voltage detection device is detected. Furthermore, if it can be assumed that all the battery elements behave the same, for example in the new state of the battery system, the first of the recorded voltages can be calculated or estimated by multiplying the sum voltage assigned to the first pair of adjacent battery elements by 0.5 and adding an uncertainty factor. Furthermore, the voltage assigned to the other battery element of the first pair of adjacent battery elements can be calculated or estimated by multiplying the total voltage assigned to the first pair of adjacent battery elements by 0.5 and subtracting an uncertainty factor. The uncertainty factor can depend on factors such as the aging of the battery system, the history of the battery system (voltage variations of the battery elements in the event of a failure), the state of charge of the battery system, the temperature of the battery system, and others. If, however, it is found that a battery element of the first pair of battery elements is defective, the battery system is preferably switched off for safety reasons as a further step in the procedure. The term "motor vehicle" as used here refers in particular to a passenger car, including all types of motor vehicles, hybrid and battery-powered electric vehicles, as well as vehicles such as sedans, vans, buses, trucks, delivery vans, and the like. In particular, a vehicle