Method for fault detection in an electrical energy storage system

Abstract

The invention relates to a method for fault detection in an electric energy storage system (100), the electric energy storage system comprising a plurality of electric energy storage units (111, 112, 113, 114) in a series circuit, the method comprising the following steps: a) detecting a first voltage generated by a first electric energy storage unit of the plurality of electric energy storage units (111, 112, 113); b) detecting a second voltage generated by the first electric energy storage unit (111, 112, 113) and a second electric energy storage unit (112, 113, 114) connected downstream in the series circuit; c) detecting a fault in voltage detection of one of the plurality of electric energy storage units (111, 112, 113, 114) and / or a fault of one of the plurality of electric energy storage units (111, 112, 113, 114) based on the detected voltage. A corresponding device (130), an electric energy storage system (100) and a computer program are also described.

Description

Technical Field

[0001] The invention relates to a method for fault detection in an electrical energy storage system having a plurality of electrical energy storage cells, a corresponding device, a corresponding electrical energy storage system and a corresponding computer program. Background Art

[0002] An electrical energy storage system having a plurality of electrical energy storage units, in particular a battery system having battery cells, typically comprises electronic components which detect the voltage and temperature of the electrical energy storage units. However, it is not possible to precisely locate a fault on an electrical energy storage unit or on or in the electronic components. This is particularly important for autonomously operated vehicles, for example in order to avoid a sudden failure of the autonomous vehicle.

[0003] JP 2013 094032 describes a battery monitoring system which detects faults in the voltage measurement during equalization of the states of charge between battery cells.

[0004] Document US 2014 / 0159739 A1 describes a battery monitoring system which detects faults in voltage measurement by means of individual voltage measurements and overall battery voltage measurement. Summary of the invention

[0005] The invention discloses a method for fault detection in an electric energy storage system, wherein the electric energy storage system comprises a plurality of electric energy storage units which are connected in series. The method comprises the following steps.

[0006] A first voltage generated by a first electrical energy storage cell of the plurality of electrical energy storage cells is detected.

[0007] Furthermore, a second voltage is detected which is generated by the first electrical energy storage cell and a second electrical energy storage cell which is connected downstream in the series circuit.

[0008] Furthermore, a fault in the voltage detection and / or a fault in one of the plurality of electrical energy storage cells is detected based on the detected voltage.

[0009] This is advantageous because it allows a distinction to be made between a fault in the energy storage unit (for example caused by an internal short circuit within the energy storage unit or lithium deposition on the electrodes) and a fault in the voltage detection. This is particularly advantageous because a fault in the energy storage unit can lead to a shutdown of the energy storage system, while the energy storage system can continue to operate despite a fault in the voltage detection. In this case, the first step can also be performed after the second step, so the order of the voltage detection is not important.

[0010] Further advantageous embodiments of the invention are the subject matter of the dependent claims.

[0011] In addition, a third voltage is suitably detected, which is generated by the second electrical energy storage unit. Here, the step of detecting a fault in the voltage detection and / or a fault in one of the plurality of electrical energy storage units based on the detected voltage now includes a first detection whether the detected first voltage is faulty. This can be done, for example, by checking whether the detected voltage is outside a predefined voltage band that is typical for the corresponding electrical energy storage unit, for example for a lithium-ion cell in the range of 2.5 volts to 4.3 volts. In addition, the check can be embodied in whether the deviation from the previously detected voltage value exceeds a physically explainable value and is therefore physically not achievable without the fault taking effect. Therefore, these situations lead to the detection of a fault.

[0012] In addition, the aforementioned steps include a second detection, whether the detected second voltage has a fault, and a third detection, whether the detected third voltage has a fault. In addition, the steps then include a fourth detection of a fault in voltage detection and / or a fault of one of the electrical energy storage units based on the detection results.

[0013] This is advantageous since faults can thereby be detected quickly and reliably.

[0014] The fourth detection advantageously includes detecting a fault in the voltage detection if the detected voltage is detected as faulty in the first detection and the third detection respectively and the detected second voltage is not detected as faulty in the second detection. Thus, a fault in the electrical energy storage unit can be distinguished in an advantageous manner and the electrical energy storage system can continue to be operated.

[0015] The fourth detection advantageously includes detecting a fault in one of the electrical energy storage units if the detected first voltage was not detected as faulty in the first detection and the detected voltage was detected as faulty in the second detection and the third detection, respectively. Thus, a fault in the voltage detection can be distinguished in an advantageous manner and a shutdown of the electrical energy storage system can be initiated.

[0016] Furthermore, a fourth voltage is expediently detected, which is generated by the second electrical energy storage unit and the third electrical energy storage unit connected downstream in the series circuit. Furthermore, the step of detecting a fault in the voltage detection and / or a fault in one of the plurality of electrical energy storage units now includes a fifth detection, whether the detected fourth voltage is faulty, and the fourth detection also includes additionally detecting a fault in the voltage detection and / or a fault in one of the electrical energy storage units based on the detection result of the fifth detection. This is advantageous because the reliability of the conclusions about the fourth detection result is increased by the additional measurement and detection.

[0017] Expediently, a fault in the voltage detection of one of the plurality of electrical energy storage units is detected, wherein in the first detection and in the third detection the respective detected voltage is detected as faulty if the respective detected voltage is outside a predefined first voltage range, wherein the predefined first voltage range relates to the first electrical energy storage unit and / or the second electrical energy storage unit, and in addition, in the second detection the detected second voltage is not detected as faulty if it is within a value of twice the predefined first voltage range. This is advantageous because the pattern of the measured voltages indicates a fault in the voltage detection, which can therefore be detected directly and allow corresponding remedial measures.

[0018] Advantageously, if the first voltage detected in the first detection is not detected as faulty, a fault in one of the electrical energy storage units is detected if the detected first voltage is within a predefined second voltage range, wherein the predefined second voltage range relates to the first electrical energy storage unit and / or the second electrical energy storage unit, and if the detected second voltage is outside a value that is twice the predefined second voltage range, then the second voltage detected in the second detection is detected as faulty, and if the detected third voltage is outside the predefined second voltage range, then the third voltage detected in the third detection is detected as faulty.

[0019] This is advantageous since the pattern of the measured voltages means a fault in one of the electrical energy storage cells, which can therefore be detected directly and allow corresponding remedial measures, such as, for example, the above-mentioned shutdown of the electrical energy storage system.

[0020] The electrical energy storage system expediently comprises at least four electrical energy storage cells, wherein the corresponding method steps are respectively carried out for two and / or three directly consecutively connected electrical energy storage cells in series until the voltage of all of the at least four electrical energy storage cells has been detected at least once, and wherein a fault in the voltage detection and / or a fault of the electrical energy storage cell is localized within the electrical energy storage system based on the detection result. This is advantageous because both fault detection and fault localization are thereby possible, which simplifies maintenance and, if necessary, only subsystems of the electrical energy storage system need to be shut down, for example, by shutting down only individual modules in which a fault is present in the battery system.

[0021] Furthermore, the subject matter of the invention is a device for fault detection of an electrical energy storage system having a plurality of electrical energy storage cells connected in series, wherein the device comprises at least one component, in particular an electronic control unit, which is configured to implement the disclosed method. The advantages mentioned are thus achieved.

[0022] The at least one component may include, for example, a battery management controller and corresponding power electronics, such as an inverter, as well as current sensors and / or voltage sensors and / or temperature sensors. The electronic control unit, in particular in the embodiment as a battery management controller, may also be such a component.

[0023] The subject matter of the invention is also an electrical energy storage system having a plurality of electrical energy storage cells connected in series, which comprises the above-described device. The advantages mentioned are thereby achieved.

[0024] Furthermore, the subject matter of the invention is a computer program comprising instructions for causing the device to carry out all the steps of the method. The advantages mentioned are thereby achieved.

[0025] An electrical energy storage unit can be understood in particular as an electrochemical battery cell and / or a battery module having at least one electrochemical battery cell and / or a battery pack having at least one battery module. For example, the electrical energy storage unit can 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 can be a lithium-ion battery cell or a lithium-ion battery module or a lithium-ion battery pack. Furthermore, the battery cell can be of the type of lithium polymer battery, nickel metal hydride battery, lead acid battery, lithium air battery or lithium sulfur battery or, in general, a battery of any electrochemical composition. Capacitors can also be used as electrical energy storage units. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Advantageous embodiments of the invention are shown in the drawings and are explained in more detail in the following description.

[0027] It shows:

[0028] Figure 1 A schematic diagram of the disclosed device and the disclosed electrical energy storage system according to one embodiment is shown;

[0029] Figure 2 A flow chart of the disclosed method according to a first embodiment is shown;

[0030] Figure 3 shows a flow chart of the disclosed method according to a second embodiment;

[0031] Figure 4 A flow chart of the disclosed method according to a third embodiment is shown. DETAILED DESCRIPTION

[0032] The same reference numerals denote the same device parts or the same method steps in all the figures.

[0033] Figure 1A schematic diagram of a disclosed device 130 and a disclosed electrical energy storage system 100 according to one embodiment is shown. In this case, the device 130 has a plurality of inputs in order to detect the voltage of the electrical energy storage units, in this case battery cells 111 , 112 , 113 , 114 . For this purpose, corresponding detection lines 101 , 102 , 103 , 104 , 105 are installed. In addition, the device 130 has a component that is provided for carrying out the disclosed method for fault detection, such as an electronic control unit that is programmed accordingly. The electrical energy storage system 100 has two terminal poles 121 , 122 , to which, for example, an inverter or an electric motor can be connected. For example, a fault may occur, in that the sensor line 102 is damaged, for example due to a cable break. It is also possible that a fault may occur, in that the battery cell 112 is damaged and no longer provides voltage.

[0034] Figure 2 A flow chart of the disclosed method for fault detection in an electrical energy storage system according to a first embodiment is shown. In a first step S21, a voltage generated by a first electrical energy storage unit of a plurality of electrical energy storage units is detected. Figure 1 When the electrical energy storage system 100 is connected, the voltage generated by the battery cell 111 is detected via the detection wires 101 and 102 of the device 130.

[0035] In a second step S22, a second voltage is detected which is generated by the first electrical energy storage unit and the second electrical energy storage unit connected downstream in the series circuit. Figure 1 When the electrical energy storage system 100 is connected to the power supply 100 , the voltage generated by the battery cells 111 , 112 is detected by the device 130 via the detection lines 101 , 103 .

[0036] In a third step S23, a fault in the voltage detection of one of the plurality of energy storage units or a fault of one of the plurality of energy storage units is detected based on the detected voltage. Figure 1 When detecting an electrical energy storage system 100 , for example, it is possible to detect when a detection line 102 is damaged, since this is reflected in the detected voltage.

[0037] Figure 3 A flow chart of the disclosed method for fault detection in an electrical energy storage system comprising a plurality of electrical energy storage cells according to a second specific embodiment is shown. In a first step S31 , a first voltage generated by a first electrical energy storage cell of the plurality of electrical energy storage cells is detected.

[0038] In a second step S32 , a second voltage is detected which is generated by the first electrical energy storage cell and a second electrical energy storage cell connected downstream in the series circuit.

[0039] In a third step S33 , a third voltage generated by the second electrical energy storage cell is detected.

[0040] In a fourth step S34, a first detection is performed to determine whether the detected first voltage is faulty. This can be done, for example, by checking whether the detected value is outside a predefined voltage range that does not occur during normal operation of the electrical energy storage system. If the detected voltage is faulty, for example because Figure 1 If the detection line 102 in the battery is damaged, this is determined here. However, a faulty voltage detection cannot yet be clearly attributed to a fault. The battery cell 111 or the detection line 101 or the detection line 102 may be damaged.

[0041] In the fifth step S35, a second detection is performed to determine whether the detected second voltage is faulty. If this is not the case, for example, Figure 1 If, in the electrical energy storage system 100 , a double battery cell voltage is detected between the detection line 101 and the detection line 103 , the detection line 102 located therebetween is damaged.

[0042] In the sixth step S36, a third detection is performed to determine whether the detected third voltage is faulty. If this is the case, the evaluation in the fifth step S35 confirms that the detection wire 102 is damaged.

[0043] The order of the steps can be varied completely and the aforementioned steps can be performed in parallel if necessary. For example, the first voltage can be detected and the first detection can be connected at the same time, and the detection of the second voltage can only be carried out subsequently.

[0044] In a seventh step S37 , a fourth detection is performed based on the detection results of the fourth step S34 , the fifth step S35 and the sixth step S36 to determine whether there is a fault in the voltage detection of one of the multiple energy storage cells or a fault within one of the energy storage cells, such as a short circuit within the cell.

[0045] Therefore, it is detected based on the results of the fourth step S34 , the fifth step S35 , and the sixth step S36 that there is a fault in the voltage detection caused by the damaged detection wire 102 .

[0046] Depending on the result of the detection in the seventh step S37 , if there is a fault in an electrical energy storage unit, for example the withdrawal of energy from the electrical energy storage system can be interrupted.

[0047] Figure 4 A flow chart of the disclosed method for fault detection in an electrical energy storage system according to a third embodiment is shown. In this case, the electrical energy storage system comprises at least four electrical energy storage units, such as Figure 1. The method is started, for example, when the electrical energy storage system is activated and in a first step S41 and a second step S42, for example, the respective voltages of the first electrical energy storage unit or the first electrical energy storage unit and the downstream second electrical energy storage unit are detected in a manner similar to steps S21, S22. In a third step S43, it is then checked whether there is a fault in the voltage detection of one of the at least four electrical energy storage units and / or a fault in one of the at least four electrical energy storage units.

[0048] If a fault is present, a fourth step S44 is carried out, for example the electrical energy storage system is switched off or, alternatively, the electrical energy storage system is only operated further at reduced power, in particular if the fault does not involve an electrical energy storage unit.

[0049] If there is no fault, the first step S41 is performed again, but now continues with the second electrical energy storage unit. The first step S41 is followed by the corresponding steps mentioned with the correspondingly moved electrical energy storage unit, so that the method monitors the electrical energy storage unit until a corresponding fault is detected or the electrical energy storage system is shut down from the outside.

[0050] This type of monitoring, which in a block always observes two or three electrical energy storage cells and then continues with a corresponding further block, makes it possible to localize faults in electrical energy storage systems of any size.

Claims

1. A method for fault detection in an electrical energy storage system (100), the electrical energy storage system comprising a plurality of electrical energy storage units (111, 112, 113, 114) connected in series, the method The following steps are involved: a) detecting a first voltage generated by a first electrical energy storage unit of a plurality of electrical energy storage units (111, 112, 113); b) detecting a second voltage generated by the first electrical energy storage unit (111, 112, 113) and a second electrical energy storage unit (112, 113, 114) connected downstream in the series circuit; c) detecting a fault in voltage detection of one of the plurality of electrical energy storage units (111, 112, 113, 114) and / or a fault of one of the plurality of electrical energy storage units (111, 112, 113, 114) based on the detected voltage, wherein the electrical energy storage system (100) has at least a first electrical energy storage unit (111, 112, 113) and a second electrical energy storage unit (112, 113, 114) interconnected in series, the method further comprising the following steps: d) detecting a third voltage generated by the second electrical energy storage unit (112, 113, 114); Wherein step c) comprises: e) whether the first voltage detected by the first detection is faulty; f) whether the second voltage detected by the second detection is faulty; g) whether the third voltage detected by the third detection is faulty; h) fourthly detecting a fault in voltage detection of one of the plurality of electrical energy storage units (111, 112, 113, 114) and / or a fault of one of the plurality of electrical energy storage units (111, 112, 113, 114) based on the detection results in steps e), f) and g), wherein step h) comprises detecting a fault in the voltage detection of one of the plurality of electrical energy storage units (111, 112, 113, 114) if the detected voltage is detected as faulty in steps e) and g) respectively and the detected second voltage is not detected as faulty in step f), and / or Step h) comprises detecting a fault in one of the electrical energy storage cells (111, 112, 113, 114) if the detected first voltage was not detected as faulty in step e) and the detected voltage was detected as faulty in each of steps f) and g).

2. The method according to claim 1, further comprising: The following steps are involved: i) detecting a fourth voltage generated by the second electrical energy storage unit (112, 113, 114) and a third electrical energy storage unit (113, 114) connected downstream in the series circuit; Wherein step c) comprises: j) a fifth detection, determining whether the detected fourth voltage has a fault; Therein, step h) comprises, in addition, detecting a fault in the voltage detection and / or a fault in one of the electrical energy storage cells (111, 112, 113, 114) as a function of the detection result of step j).

3. The method according to claim 1, in, In step e) and step g), if the detected voltage is outside a predefined first voltage range, the detected voltage is detected as faulty, respectively, wherein the predefined first voltage range is related to the first electrical energy storage unit (111, 112, 113) and / or the second electrical energy storage unit (112, 113, 114), and in step f), if the detected second voltage is within a value twice the predefined first voltage range, the detected second voltage is not detected as faulty.

4. The method according to claim 1, in, In step e), if the detected first voltage is within a predefined second voltage range, the detected first voltage is not detected as faulty, wherein the predefined second voltage range is related to the first electrical energy storage unit (111, 112, 113) and / or the second electrical energy storage unit (112, 113, 114), and if the detected second voltage is outside a value twice the predefined second voltage range, the detected second voltage is detected as faulty in step f), and if the detected third voltage is outside the predefined second voltage range, the detected third voltage is detected as faulty in step g).

5. The method according to any one of claims 1 to 4, in, The electrical energy storage system (100) comprises at least four electrical energy storage units (111, 112, 113, 114), wherein corresponding method steps are respectively carried out for two and / or three electrical energy storage units (111, 112, 113, 114) directly connected in series, at least until a fault is detected, and wherein faults in voltage detection and / or faults of electrical energy storage units (111, 112, 113, 114) within the electrical energy storage system (100) are localized based on the detection results.

6. A device (130) for fault detection of an electrical energy storage system (100) having a plurality of electrical energy storage units (111, 112, 113, 114) connected in series, in, The device (130) comprises at least one component, in particular an electronic control unit, which is configured to carry out the steps of the method according to any one of claims 1 to 5.

7. An electrical energy storage system (100) having a plurality of electrical energy storage cells (111, 112, 113, 114) connected in series, the electrical energy storage system comprising the device (130) according to claim 6.

8. A computer program comprising instructions for causing the device (130) according to claim 6 to implement all the steps of the method according to any one of claims 1 to 5.

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