CN112034361A - Method for detecting errors in an electrical energy storage system - Google Patents

Abstract

A method for detecting errors in an electrical energy storage system is described, wherein the electrical energy storage system comprises at least two branches connected in parallel, wherein each branch has at least two electrical energy storage units connected in series, the The method includes the following steps: a) detecting the first voltage of the first electrical energy storage unit of the first branch; b) checking whether the detected first voltage has errors; c) detecting the second electrical energy storage unit of the second branch the second voltage of the unit; d) check whether the detected second voltage has errors; e) according to the inspection results of steps b) and d), detect errors in the voltage detection in the electric energy storage system or in the electric energy storage system Defective electrical energy storage unit in the system. Corresponding devices, electrical energy storage systems and computer programs are also described.

Description

Method for detecting errors in electrical energy storage systems

technical field

The present disclosure is based on a method for detecting errors in an electrical energy storage system, a corresponding device for detecting errors, a corresponding electrical energy storage system with a corresponding device, and a corresponding computer program.

Background technique

Electrical energy storage systems with a plurality of electrical energy storage cells, particularly battery systems with battery cells, typically include electronic components that detect the voltage and temperature of the electrical energy storage cells. However, it is not possible to precisely locate errors on or in the electrical energy storage unit or on or in the electronic components. This is particularly important for autonomously operating vehicles, for example because sudden failure of said autonomous vehicle is to be avoided.

In document US 2014/0129164 a system for monitoring a battery is described which works with a multiplexer and monitors the voltage of said battery.

In document CN1101938C a method for monitoring a battery is described in which eg the voltage is continuously detected and an alarm is triggered when a limit value is exceeded.

SUMMARY OF THE INVENTION

Advantages of the present invention

A method for detecting errors in an electrical energy storage system is disclosed, wherein the electrical energy storage system comprises at least two parallel-connected branches, each branch having at least two series-connected electrical energy storage units. The method includes the following steps.

The first voltage is detected from the first electric energy storage unit of the first branch, and then it is checked whether the first voltage is wrong. Here, an error can be, for example, exceeding or falling below a predefined voltage limit. For example, detection of a voltage of substantially 0V indicates a defective electrical energy storage unit, but may also be a defect in the equipment required to detect the voltage. Here, the voltages of all energy storage cells in the first branch can be detected and checked for errors.

A second voltage is detected from the second electric energy storage unit of the second branch, and then the second voltage is checked for errors. Here, errors can be detected as described above. Here, the voltages of all energy storage cells in the second branch can be detected and checked for errors.

Next, an error in the voltage detection in the electric energy storage system or an error in a defective electric energy storage unit in the electric energy storage system is detected on the basis of the inspection result. Depending on the error pattern that occurs, it is possible to distinguish, for example, whether there is an error in the voltage detection or the presence of a defective electrical energy storage unit. Based on this result, a further method step can then be carried out, in which the branch with the defective electrical energy storage unit is disconnected, for example by means of a switch.

This is advantageous because different method steps or operations can be carried out depending on the detected error pattern in order to ensure the safety or continued operation of the electrical energy storage system. For example, a defective electrical energy storage unit is critical to the safety of the electrical energy storage system, and the flow of corresponding energy into or out of the electrical energy storage unit should be prohibited. In the event of an error in the voltage detection, the electrical energy storage system can, if necessary, continue to operate with reduced power by using the voltage value detected before the error occurred in order to predict the corresponding voltage value. Thus, disconnection of the corresponding branch or the entire electrical energy storage system can be avoided in this case.

Here, the sequence of the method steps can be chosen arbitrarily, as long as the voltage is detected before the corresponding check of the voltage. For example, all voltages can be detected first and then checked, which can also be performed in parallel for the at least two branches, eg on a multiprocessor system.

Further advantageous embodiments of the invention are the subject of the dependent claims.

Expediently, the first voltage of the first electrical energy storage unit of the first branch is rechecked, and then the first voltage is rechecked for errors. Errors in the voltage detection in the electric energy storage system or faults in defective electric energy storage cells in the electric energy storage system are then additionally detected on the basis of the results of the new inspection. This facilitates achieving a higher accuracy of conclusions about the error or improving the discrimination between the detection of an error in the voltage detection and the detection of a defective electrical energy storage unit.

Expediently, the voltages of at least two electrical energy storage units arranged in different branches are detected by a common voltage detection device. This is advantageous since the number of voltage detection devices can thereby be reduced and a higher accuracy of conclusions about the error is achieved when the voltages of the different electrical energy storage cells are detected by the common voltage detection device Or an improved discrimination between the detection of an error in the voltage detection and the detection of a defective electrical energy storage unit.

Suitably, an error in the voltage detection is detected if it is determined that there is an error in the detected voltage when checking the detected first voltage for errors and when checking the detected second voltage for errors, respectively. This is advantageous because such errors can thus be detected reliably, which allows corresponding measures to be taken to ensure safety.

Suitably, an error in the voltage detection is detected if, upon rechecking the re-detected first voltage for error, it is still determined that there is an error. This is advantageous because there is further evidence that the voltage detection is erroneous, and thus significantly improves the quality of conclusions about voltage detection errors.

Suitably, the voltage is detected by the common voltage detection device in the above-mentioned steps. This is advantageous because there are thus several inspection results for one voltage detection device, which increases the confidence that there is an error in said voltage detection device.

Suitably, upon detection of an error in the voltage detection in the electrical energy storage system or upon detection of a defective electrical energy storage unit in the electrical energy storage system, the switch arranged in the branch is opened , in order to inhibit the flow of energy from the branch. In this case, the branch has errors in the voltage detection or in the electrical energy storage cells identified as defective. This is advantageous in preventing lasting damage to the electrical energy storage system or even endangering the user.

Alternatively, the electrical energy storage system can also be operated with reduced power, which can be advantageous in particular in the case of errors in the voltage detection, since there is a good chance that there are still reliable measurements from previous measurements. value, these measurements can be used to estimate the voltage range of the corresponding electrical energy storage unit. A complete failure of the electrical energy storage system is thus avoided in an advantageous manner. The corresponding actuation can be carried out, for example, for the inverter or for the converter in general.

Suitably, the voltage is detected and checked for all electrical energy storage units in a branch and for all branches, respectively, wherein each electrical energy storage unit in a plurality of electrical energy storage units in different branches is detected by said common voltage detection device. The voltage of the energy storage unit. In this case, errors in the voltage detection in the electric energy storage system or defective electric energy storage cells in the electric energy storage system are detected on the basis of the results of the inspection of the voltages detected by the common voltage detection device. This is advantageous because as the number of voltages detected and checked increases, the quality of the conclusions about whether there is an error in the voltage detection or a defective energy storage cell improves.

Furthermore, the subject of the present disclosure is an apparatus for detecting faults in an electrical energy storage system, wherein the electrical energy storage system comprises at least two parallel-connected branches, wherein each branch has at least two series connections An electrical energy storage unit, wherein the apparatus comprises at least one device, in particular an electronic control unit. Here, the device is designed to carry out the steps of the above-described method, for example by corresponding programming. The above-mentioned advantages are thus achieved.

Furthermore, the subject matter of the present disclosure is an electrical energy storage system comprising the above-described apparatus. The above-mentioned advantages are thus achieved.

Furthermore, the subject matter of the present disclosure is a computer program comprising commands to cause the described apparatus to perform all the steps of the described method.

An electrical energy storage unit is to be understood in particular as an electrochemical cell and/or a battery module having at least one electrochemical cell and/or a battery having at least one battery module. For example, the electrical energy storage unit may be a lithium-based battery cell or a lithium-based battery module or a lithium-based battery pack. In particular, the electrical energy storage unit may be a lithium-ion battery cell or a lithium-ion battery module or a lithium-ion battery pack. Furthermore, the battery cells can be of the type of lithium polymer batteries, nickel metal hydride batteries, lead acid batteries, lithium air batteries or lithium sulfur batteries, or, in general, batteries of any electrochemical composition. Capacitors can also act as electrical energy storage units.

The at least one device may comprise, for example, a battery management control device and corresponding power electronics, such as an inverter, and a current sensor and/or a voltage sensor and/or a temperature sensor. An electronic control unit, in particular an electronic control unit embodied as a battery management control device, can also be such a device.

An electronic control unit is to be understood in particular as an electronic control device comprising, for example, a microcontroller and/or a dedicated hardware module (eg an ASIC), but also a personal computer or a memory programmable controller.

Description of drawings

Advantageous embodiments of the invention are shown in the drawings and explained in more detail in the following description.

in:

Figure 1 shows a schematic diagram of a battery system with multiple battery branches;

Figure 2 shows a flowchart of the disclosed method according to a first embodiment;

FIG. 3 shows a flowchart of the disclosed method according to a second embodiment; and

Figure 4 shows a flowchart of the disclosed method according to a third embodiment.

Detailed ways

In all figures, the same reference numbers refer to the same equipment components or the same method steps.

FIG. 1 shows a schematic diagram of an electrical energy storage system 10 for an electric vehicle, which in the present case has two branches 6 . Each branch 6 of the electrical energy storage system 10 includes a plurality of electrical energy storage units 5 that are electrically connected to each other in series. Each electrical energy storage unit 5 comprises, for example, at least one battery cell, preferably a plurality of battery cells. The electrical energy storage system 10 for an electric vehicle may also comprise a greater number of branches 6 .

In the present case, these branches 6 can be electrically connected in parallel. These branches 6 are electrically connected to each other on the input side. As shown, each of these branches 6 may comprise a separate main switch 61 electrically connected in series with the electrical energy storage unit 5 . These branches 6 are also electrically connected to each other on the output side by closing the main switch 61 . These branches 6 are thus electrically connected in parallel when the main switch 61 is closed. The main switch 61 of the branch 6 can be designed, for example, as a contactor, an electromechanical relay or a semiconductor switch. Alternatively, the electrical energy storage units can also each have a corresponding switch in order to switch the corresponding electrical energy storage unit out of the branch without disconnecting the entire corresponding branch.

The electric energy storage system 10 further includes a plurality of monitoring units 20 for monitoring each electric energy storage unit 5 of the electric energy storage system 10 . In this case, each voltage detection device 20 is each associated with a plurality of electrical energy storage units 5 which are arranged in different branches 6 . In the present case, each voltage detection device 20 is associated with exactly two electrical energy storage units 5 . In the present case, the number of voltage detection devices 20 corresponds to the number of electrical energy storage units 5 per branch 6 .

Here, each voltage detection device 20 has a switching device 25 . A corresponding voltage detection device 20 can be connected to the respective electrical energy storage unit 5 associated therewith by means of a switching device 25 . The voltage detection devices 20 are connected by means of signal lines to the electrical energy storage units 5 associated with the respective voltage detection devices 20 . These electrical energy storage units 5 transmit data to the switching device 25 of the voltage detection device 20 via said signal lines. In this case, the corresponding switching device 25 can also be integrated into the corresponding voltage detection device 20 .

The electrical energy storage system 10 also includes a central control unit 30 . The central control unit 30 communicates with the voltage detection device 20 via signal lines. The voltage detection device 20 further transmits, in particular, data that has been transmitted from the electrical energy storage unit 5 to the switching device 25 of the voltage detection device 20 to the central control unit 30 . The central control unit 30 analyzes the data transmitted from the voltage detection device 20 .

The central control unit 30 is also connected to the main switch 61 of the branch 6 . In particular, the central control unit 30 can operate the main switch 61 of the branch 6 to open and close. If the central control unit 30 identifies an error in the electrical energy storage unit 5 by analyzing the data transmitted from the voltage detection device 20 , the central control unit 30 can open the main switch 61 of the corresponding branch 6 or open the defective circuit accordingly The corresponding switch of the electric energy storage unit.

By analyzing the transmitted data, the central control unit 30 can also determine whether there is an error in the voltage detection. If the central control unit 30 identifies errors in the voltage detection by analyzing the data transmitted from the voltage detection device 20 , the main switch of the respective branch 6 can also remain closed or, if necessary, open, depending on the application. A corresponding warning message can be generated.

The central control unit 30 is also connected to the switching device 25 of the voltage detection device 20 via a control line not shown here. The central control unit 30 controls the switching device 25 via the control line. In this case, the central control unit 30 controls, in particular, which data is to be transmitted from which of the electrical energy storage units 5 associated with the respective voltage detection device 20 and within what time period.

Figure 2 shows a flowchart of the disclosed method according to a first embodiment. An electrical energy storage system to which the method can be applied is shown, for example, in FIG. 1 or has at least two parallel-connected branches, wherein each branch has at least two series-connected electrical energy storage units.

In the first step S21, the first voltage of the first electric energy storage unit of the first branch of the electric energy storage system is detected. Then in a second step S22, it is checked whether the detected first voltage has errors, eg whether the detected first voltage has a prominently high value or a prominently low value, or has a generally implausible value .

In the third step S23, the second voltage of the second electric energy storage unit of the second branch of the electric energy storage system is detected. Then in a fourth step S24 it is checked whether the detected second voltage has errors. This can be done as described above.

In the fifth step S25, an error in voltage detection in the electric energy storage system or a defective electric energy storage unit in the electric energy storage system is detected according to the inspection result of the detected voltage. Depending on the status of the errors obtained in the checking steps S22 and S24, an error in the voltage detection (eg a specific defective voltage detection device) or a specific defective electrical energy storage unit is detected.

Figure 3 shows a flowchart of the disclosed method according to a second embodiment. In a first step S31 , the first voltage of the first electric energy storage unit of the first branch of the electric energy storage system is detected, for example by means of the voltage detection device 20 in FIG. 1 . Then in the second step S32 it is checked whether the detected first voltage is wrong. This can take place, for example, directly in the voltage detection device 20 or in the central control unit 30 or on a data processing device not shown here, to which the corresponding detected voltage is transmitted, for example, wirelessly.

In the third step S33, the second voltage of the second electric energy storage unit of the second branch of the electric energy storage system is detected. This can be done as described above. Then in a fourth step S34 it is checked whether the detected second voltage has errors. This can be done as described above.

In the fifth step S35, a case distinction is made according to the status of the errors obtained in the checking steps S32 and S34. If the check in the second step S32 yields an error in the detected voltage and the check in the fourth step S34 does not yield an error in the detected voltage, then this indicates the presence of a defective electrical energy storage unit, The defective electrical energy storage unit has, for example, an internal short circuit. In order to prove this defect, the first voltage of the first electric energy storage unit of the first branch is then rechecked in the sixth step S36. Next, in the seventh step S37, it is rechecked whether the re-detected first voltage has errors.

Assuming that it is determined here that the first voltage detected again is erroneous, for example because the detected voltage again has an implausible value, then in an eighth step S38 a defective electrical storage system is detected in the electrical storage system energy unit. In a subsequent step not shown in FIG. 3 it can be provided, for example, that the branch with the electrical energy storage unit identified as defective is opened by means of a switch, so that no current can flow from this branch.

If the check in the second step S32 yields an error in the detected voltage and the check in the fourth step S34 yields an error in the detected voltage, this indicates that there is an error in the voltage detection, for example because the corresponding sensing Device is defective. Due to the double check and detection, the first voltage need not be checked again. A ninth step S39 is then continued, in which the electric energy storage system is operated at a reduced power and/or a certain amount of energy is also set before the final disconnection, according to previously recorded reliable measurements. Remaining stroke length. Therefore, instead of an immediate disconnection, the user of the electric energy storage system still has enough time to adapt to the situation and take corresponding measures, eg manoeuvring the workshop.

Figure 4 shows a flowchart of the disclosed method according to a third embodiment. Here, in contrast to FIG. 1 , the electrical energy storage system comprises more than two parallel-connected branches, for example three parallel-connected branches, and furthermore each branch comprises more electrical energy storage units .

In a first step S41, a first voltage of a first electrical energy storage unit of a first branch of the electrical energy storage system is detected by means of a voltage detection device. Then in the second step S42 it is checked whether the detected first voltage is wrong. This can take place, for example, directly in the voltage detection device or in a central control unit or on a data processing device, not shown here, to which the corresponding detected voltage is transmitted, for example, wirelessly.

In a third step S43, it is checked whether voltage detection has been performed for all branches. If not, the first step S41 is continued, and the second voltage of the second electric energy storage unit of the second branch of the electric energy storage system is detected by means of the voltage detection device. All branches are checked in a similar manner as long as they are not checked accordingly. The same is true for the checking of the detected voltage.

After the voltage of the last branch has been detected and checked, a case distinction is made in a third step S43 according to the existing error pattern according to the status of the errors obtained in the second checking step S42.

If there is an error in the detected voltage of a certain branch in the repeated execution of the check in the second step S42, wherein all the voltages are detected by the same voltage detection device, this indicates that there is a defective electric energy storage unit, which has Defective electrical energy storage cells have, for example, an internal short circuit. In order to prove this defect, the voltage of the electric energy storage unit in which the branch of the electric energy storage unit identified as defective is then detected again in a fourth step S44 . Next, in the fifth step S45, it is rechecked whether the voltage re-detected in the fourth step S44 has errors.

Assuming that it is determined here that the re-detected first voltage of the fourth step S44 is wrong, for example because the detected voltage has an implausible value again, then in the sixth step S46 it is detected that there is a presence in the electric energy storage system Defective electrical energy storage unit. In a subsequent step not shown in FIG. 4 , it can be provided, for example, that the branch with the electric energy storage unit identified as defective is opened by means of a switch, so that no current can flow from this branch.

If the checking in the second step S42 respectively results in an error in the detection voltage detected by the same voltage detection device, this indicates that there is an error in the voltage detection, for example because the corresponding sensing device is defective. Due to multiple checks and probes, there is no need to detect the voltage again by the same voltage detection device. A seventh step S47 is then continued, in which the electric energy storage system is operated at reduced power and/or a certain residual is also set before the final disconnection, according to previously recorded reliable measurements. stroke length. Therefore, instead of an immediate disconnection, the user of the electric energy storage system still has enough time to adapt to the situation and take corresponding measures, eg manoeuvring the workshop.

Claims (12)

1. Method for detecting errors in an electrical energy storage system (10), the electrical energy storage system (10) comprising at least two parallel-connected branches (6), wherein each branch (6) has at least two series-connected electrical energy storage cells (5), the method comprising the steps of:

a) detecting a first voltage of a first electrical energy storage unit (5) of a first branch (6);

b) checking whether the detected first voltage has an error;

c) detecting a second voltage of a second electrical energy storage unit (5) of the second branch (6);

d) checking whether the detected second voltage has an error;

e) detecting an error in the voltage detection in the electrical energy storage system (10) or a defective electrical energy storage cell (5) in the electrical energy storage system (10) depending on the result of the checking of steps b) and d).

2. The method of claim 1, further comprising:

f) -re-detecting a first voltage of a first electrical energy storage unit (5) of the first branch (6);

g) re-checking whether the re-detected first voltage has an error,

wherein step e) comprises additionally detecting an error in the voltage detection in the electrical energy storage system (10) or a defective electrical energy storage cell (5) in the electrical energy storage system (10) depending on the result of the check of step g).

3. The method according to any of the preceding claims, wherein the voltages of at least two electrical energy storage cells (5) arranged in different branches (6) are detected by a common voltage detection device (20).

4. The method according to claim 3, wherein an error in the detection of the voltage is detected if it is determined at the time of the check in step b) and at the time of the check in step d), respectively, that there is an error in the detected voltage.

5. The method according to claim 4, wherein an error in the voltage detection is detected if additionally at the time of the recheck in step g) it is determined that there is an error in the rechecked first voltage.

6. A method according to claim 3, characterized in that a defective electrical energy storage cell (5) is detected in step e) if an error in the detected first voltage of the same first electrical energy storage cell (5) of the first branch is determined both at the time of the check in step b) and at the time of the recheck in step g), and no error is determined at the time of the check of the detected second voltage in step d).

7. The method according to any one of claims 4 to 6, wherein the voltages in steps a) and c) and/or f) are detected by the common voltage detection device (20).

8. Method according to any of the preceding claims, wherein upon detection of an error in the voltage detection in the electrical energy storage system (10) or upon detection of a defective electrical energy storage cell (5) in the electrical energy storage system (10), a switch (61) arranged in a branch (6) is opened in order to inhibit energy from flowing out of the branch (6), wherein the branch (6) has the erroneous or defective electrical energy storage cell (5) in the voltage detection.

9. The method according to any one of claims 3 to 8, wherein the voltages are detected and checked for all electrical energy storage cells (5) in one branch (6) and for all branches (6), respectively, wherein the voltage of each of a plurality of electrical energy storage cells (5) in different branches (6) is detected by the common voltage detection device (20), and wherein an error in the voltage detection in the electrical energy storage system (10) or a defective electrical energy storage cell (5) in the electrical energy storage system (10) is detected depending on the result of the check of the voltages detected by the common voltage detection device (21).

10. Device for detecting errors in an electrical energy storage system (10), wherein the electrical energy storage system (10) comprises at least two parallel-connected branches (6), wherein each branch (6) has at least two series-connected electrical energy storage cells (5), wherein the device comprises at least one apparatus, in particular an electronic control unit, which is designed to perform the steps of the method according to any one of claims 1 to 9.

11. Electrical energy storage system (10) comprising a device according to claim 10.

12. Computer program comprising instructions for causing an apparatus according to claim 10 to perform all the steps of the method according to any one of claims 1 to 9.

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