Method for detecting stuck switch

Abstract

The invention relates to a method for detecting a stuck switch of a battery system having a plurality of battery packs connected in parallel having mutually different battery pack voltages which cause a balancing current, comprising the following method steps: diagnosing at least one switch (30, 32, 34) for a stuck state (58) in such a way that the at least one switch (30, 32, 34) can be switched on or off; the battery (12, 14, 16), the balancing current (36, 39, 40) of which has a value of 0, is regarded as a battery having an open switch, the diagnosis being carried out only if at least one balancing current between the battery (12, 14, 16) falls below a threshold value, and / or the at least one switch (30, 32, 34) is diagnosed for an open-jamming state (60) in such a way that the at least one switch (30, 32, 34) does not fall below the threshold value. In this way, the battery pack (12, 14, 16) recognizes a positive diagnostic result when a balancing current (36, 39, 40) is recognized and, on the other hand, a switching failure is inferred if the balancing current (36, 39, 40) does not occur.

Description

Technical Field

[0001] This invention relates to a method for identifying a stuck switch in a battery system having multiple battery packs connected in parallel. Furthermore, this invention relates to the application of the method for identifying switches in multi-functional systems or vehicle systems. Background Technology

[0002] Regular checks of the battery system are crucial for the proper functioning of the switch. Current technology uses diagnostic functions based on monitoring the connection voltage (Linkspannung). This monitoring takes into account the principle that the connection voltage drops after the switch is turned off. If the voltage reaches a predetermined lower threshold, it is assumed that the switch has been turned off as intended. If other operations (such as battery charging or discharging) rely on a reliably turned-off switch, the delayed drop in connection voltage can significantly extend the overall diagnostic time. Furthermore, the varying rate of voltage drop due to its variability varies drastically depending on vehicle type and specific conditions within the relevant project, leading to variations in diagnostic time and making process standardization difficult.

[0003] In systems with battery packs connected in parallel, all switches must be disconnected to identify drops in connection voltage and ensure functional performance. If the connection voltage does not drop during the check, it is impossible to definitively determine which switch is not disconnected. The challenge of definitively identifying the switches that are not disconnected increases the complexity of error elimination and can lead to longer vehicle downtime.

[0004] A relay diagnostic device for a parallel battery pack arrangement is known from US2022 4044 18A1, the battery pack arrangement having: a first battery pack with a first battery module and a first positive relay, and a second battery pack with a second battery module and a second positive relay. The device includes a diagnostic unit comprising a diagnostic switch and a diagnostic resistor connected between the first battery pack connector and the second battery pack connector. Furthermore, the device includes a first detector for detecting the current of the first battery module, and a second detector for detecting the current of the second battery module. Additionally, a control unit is known that collects a first detection value and a second detection value from either the first or second detector during a first diagnostic cycle. A key feature of this diagnostic cycle is that the first and second positive relays are disconnected and the diagnostic switch is closed.

[0005] A contactor diagnostic device is known from KR 2020 0050 865A. This device includes a detection unit mounted at each current path of a plurality of parallel-connected battery modules and configured such that the detection unit measures the current flowing in a plurality of switches connected in parallel with each other. A control unit is configured to output a contactor control signal that controls the plurality of switches to an operating state of either an off or on state, and to calculate the current fluctuation range flowing through each of the plurality of switches, more specifically based on a pre-given reference fluctuation value. Summary of the Invention

[0006] According to the present invention, a method for identifying stuck switches in a battery system having multiple battery packs connected in parallel, the battery packs having different battery pack voltages that cause balancing currents, the method comprising the following steps:

[0007] i) For a stuck state, at least one switch is diagnosed such that a battery pack with a balance current of 0 is considered a battery pack with an open switch, wherein the diagnosis is performed only when at least one balance current between the battery packs drops below a critical value, and / or

[0008] ii) For at least one switch in the open-blocking state, the battery pack identifies a positive diagnostic result if a balancing current is detected, and infers a switch failure if no balancing current is detected.

[0009] Stuck A switch, for example an electromagnetic switch, is in a state where it does not switch between the open and closed positions as intended. Instead, the switch remains in one position, which either results in continuous current flow or a continuous interruption of current. This can lead to malfunction of connected appliances and interference with their operation.

[0010] When a stuck switch is detected, a functional failure is considered to exist. Therefore, early identification of stuck switches is crucial to ensure the safe and reliable functioning of electrical systems, such as vehicle systems. A stuck switch can not only adversely affect connected appliances but also compromise the entire electrical system. The method according to the present invention enables timely diagnosis of stuck switches, thus preventing operational interference and subsequent damage. Consequently, improvements are achieved in the functionality and safety of systems, such as vehicle systems.

[0011] A stuck state indicates a switch condition where, when the switch is opened to start, a positive diagnostic result (i.e., the switch is open) is identified if the switch is successfully opened, and a stuck state is identified if the switch is not opened. A disconnect-stuck state indicates a switch condition where, when the open switch is initiated to close, a positive diagnostic result (i.e., the switch is closed) is identified if the switch is closed. A disconnect-stuck state is identified if the switch is not closed, indicating a switch malfunction and / or jamming.

[0012] When at least two batteries are connected in parallel simultaneously, the method according to the invention can, for example, enable diagnosis by means of current measurement, i.e., identifying stuck switches. In the advantageous solution according to the invention, measurements of vehicle-dependent on-board voltage are eliminated. This significantly reduces the time spent diagnosing switches. By eliminating system dependencies, project risk is advantageously reduced, as is development time for vehicle integration, for example. Another advantage is the identification of switches with corresponding faults. This simplifies troubleshooting in the workshop and reduces warranty costs, as not all switches are classified as faulty.

[0013] For example, after battery use or due to varying self-discharge rates, slightly different battery pack voltages often occur. In a system with two battery packs connected in series, a balancing current is generated due to the difference in battery pack voltages. This balancing current can be defined, for example, such that a first current I1, i.e., the current of the first battery pack, equals a second current I2, i.e., the current of the second battery pack (I2 = -I1). In a dual-battery pack system, the balancing current is defined as the difference between the voltages of the first and second battery packs divided by the sum of the resistances of the first and second battery packs. A calculable balancing current is also generated when two or more battery packs are connected in parallel, and this balancing current flows even at higher temperatures, lower battery pack resistances, and for a sufficiently long duration.

[0014] After the battery has been running, in the first method step for identifying stuck switches, all switches must be checked for a stuck state. During this time, no current I4 flows to the system, such as the vehicle; instead, the balancing current between the batteries flows. In certain cases, this balancing current can reach a significant level, so wait until the balancing current is below a critical value (e.g., 2-3A). Alternatively, wait until at least one of the balancing currents has reached the critical value. This allows disconnection of the battery pack with balancing currents below the critical value. Advantageously, it is not necessary to wait until all balancing currents are below the critical value. This prevents premature aging of the switches. Battery packs with currents below the critical value (e.g., the third switch in a three-pack system) can be disconnected. In this case, determine whether the third balancing current I3 of the third switch jumps to 0A. If it jumps to 0A, all other currents of the other switches change. The balancing current I3 jumping to 0A can be assessed as a successful switch disconnection. Alternatively, all other changes in current can also be interpreted as switch disconnection. This is necessary, for example, in the case of a faulty current sensor in the disconnected battery pack. Once only one switch is closed, the balancing current stops flowing and the previously open switch must be closed again. After the balancing current resumes flowing, the remaining switches can be inspected.

[0015] After the first method step i) for diagnosing the stuck state is completed, the switch is checked according to the second method step ii) for diagnosing the open-stuck state. To perform this method step ii), the switch for each battery pack must be closed, or at least the switches for two battery packs must be closed. If a balancing current is detected in the battery pack, the switch is considered successfully closed and a positive diagnostic result is obtained, i.e., normal operation and no switch sticking. If no balancing current is detected in the battery pack, this could be due to, for example, the superposition of other balancing currents. In this case, another combination of switch closing sequences should be implemented. If no balancing current is present in each combination of other switch positions, the stuck switch is assumed to be a fault in the open-stuck state according to the method of the present invention.

[0016] In an advantageous improvement of the method according to the present invention, at least one switch is checked for a stuck state before performing step i), balancing the flow of current and preventing current I4 from flowing toward the vehicle system.

[0017] In an advantageous improvement of the method according to the present invention, according to step i), the critical value is preferably between 2A and 3A.

[0018] In an advantageous improvement of the method according to the present invention, the switch is disconnected in the battery pack in which the balance current is below a critical value, such that the relevant balance current has a value of 0.

[0019] In an advantageous improvement of the method according to the present invention, after performing method steps i) to ii) and completing the first diagnosis for the stuck state "stuck-closed", an additional second diagnosis is performed on the switch for the open-stuck state "stuck-open".

[0020] In an advantageous improvement to the method proposed according to the present invention, at least two switches are closed within the framework of a second diagnosis of the switches.

[0021] In an advantageous improvement of the method according to the present invention, a disconnection is identified and a positive diagnostic result of a second diagnosis is determined when a balancing current appears at one of the battery packs in the relevant switch's battery pack.

[0022] In an advantageous improvement of the method according to the present invention, it is inferred that an open-blocking state exists at one of the switches when a balancing current is missing in each combination of the switching states of the switch.

[0023] Furthermore, the application of the method for identifying switches in multifunctional systems is proposed.

[0024] Furthermore, the application of the method for identifying switches in vehicle systems is proposed.

[0025] Advantages of this invention:

[0026] An advantageous feature of the method according to the invention is its ability to perform rapid and particularly efficient diagnostics on each individual switch without relying on individual system characteristics. This results in robust usability, especially as system characteristics change throughout the system's lifespan. This is particularly advantageous in evolving technological landscapes where systems and components are frequently updated or replaced, as it ensures the method according to the invention remains effective in future environments and applications.

[0027] Furthermore, failures in other system components can lead to incorrect diagnoses, which can be avoided by the method according to the present invention. In addition, this feasible solution offers another key advantage: accurate identification of stuck switches and targeted focus on the relevant switches. This targeted approach significantly improves efficiency within the scope of error analysis, resulting in shorter system downtime and higher overall availability.

[0028] Precisely locating faults based on stuck switches helps minimize unnecessary downtime and thereby improves overall operational efficiency. This enables businesses to plan all production processes more smoothly and reduce bottlenecks or unplanned downtime, which in turn improves overall performance and profitability.

[0029] Furthermore, the independence of system-specific features ensures flexibility and adaptability, thus making the method according to the invention suitable for a variety of applications and environments. The flexibility of the solution according to the invention improves practical usability and enables its integration into different industries and system configurations.

[0030] In a world that increasingly emphasizes interoperability and integration, the method according to this invention enables seamless integration into existing systems and infrastructure without requiring significant adaptation or modification. By combining rapid diagnostics, precise fault location, and system-independent usability, it enables more efficient and reliable identification of stuck switches, thereby maximizing uptime and improving overall system performance.

[0031] Therefore, the method according to the present invention enables timely diagnosis of stuck switches, and thus avoids operational interference and subsequent damage. This optimizes the functionality and safety of systems, such as vehicle systems. Attached Figure Description

[0032] Embodiments of the present invention will be explained in detail with reference to the accompanying drawings and the following description.

[0033] in:

[0034] Figure 1 A schematic diagram of the circuitry for multiple battery packs is shown. Detailed Implementation

[0035] In the following description of embodiments of the invention, the same or similar elements are designated by the same reference numerals, and in some cases, repeated descriptions of these elements are omitted. The accompanying drawings are merely schematic illustrations of the subject matter of the invention.

[0036] Figure 1 A circuit diagram of multiple battery packs is shown. Figure 1 The image shows vehicle system 48, which is powered by battery system 10. Furthermore, from... Figure 1 As can be seen, the battery system 10 has a first battery pack 12, a second battery pack 14, and a third battery pack 16. Figure 1 It is concluded that the first battery pack 12 has a first battery pack voltage U Pack118. The first battery pack includes resistor R1 24, a first switch 30, and a first balancing current I1 36. The second battery pack 14 has a second battery pack voltage U. Pack2 20. The second battery pack resistor R2; 26. The second switch 32; and the second balancing current I2; 39. The third battery pack 16 has a third battery pack voltage U. Pack3 22. The third battery pack resistor R3 28, the third switch 34, and the third balancing current I3 40. Here, the so-called balancing currents I1 36, I2 39, and I3 40 are connected to the current conductor 43 for transmission, so that the current to be transmitted I4 44 is provided to the vehicle system 48 through the first, second, and third battery packs 12, 14, and 16.

[0037] In addition, Figure 1 For the corresponding battery packs 12, 14, and 16, the switching states "disconnected" 54 and "closed" 56 are respectively indicated at switches 30, 32, and 34.

[0038] In addition, from Figure 1 It can be seen that the voltage U supplied to vehicle system 48 link 42. Vehicle system 48 has the vehicle system 48 in Figure 1 The exemplary modules, vehicle resistor 52, and vehicle capacitor 50 are schematically shown. A control line 46 is connected between the battery system 10 and the vehicle system 48.

[0039] Here, the proposed method for identifying stuck switches in battery packs 12, 14, and 16 is performed, for example, as follows: First, the delivered current I4 44 is suppressed so that no current flows toward vehicle system 48. Then, a first method step i) is initiated, which includes diagnosing at least one switch 30, 32, and 34 for a stuck state 58. Within the framework of this diagnosis, battery packs 12, 14, and 16—whose balance currents I1 36, I2 39, and I3 40 have a value of 0A—are considered to have open switches. However, here, the diagnosis is only performed when the balance currents I1 36, I2 39, and I3 40 among battery packs 12, 14, and 16 drop below a critical value. Preferably, the critical value is between 2A and 3A. Alternatively, alternative critical values ​​can be considered depending on the battery system used.

[0040] Following the first method step i), the second method step ii) is initiated. The second method step includes diagnosing at least one switch 30, 32, 34 considering the disconnect-blocking state 60. During the second method step, battery packs 12, 14, 16 determine a positive diagnostic result if balancing currents I1 36, I2 39, and I3 40 are detected, and infer a fault in switches 30, 32, and 34 if balancing currents I1 36, I2 39, and I3 40 are not present.

[0041] This invention is not limited to the embodiments described herein and the aspects highlighted therein. Rather, various modifications that are within the scope of the claims and are of skill to those skilled in the art can be implemented.

Claims

1. A method for identifying a stuck switch in a battery system (10), the battery system having a plurality of battery packs (12, 14, 16) connected in parallel, the battery packs having different battery pack voltages (18, 20, 22) that cause balancing currents (36, 39, 40), the method comprising the following steps: i) For a jammed state (58), at least one switch (30, 32, 34) is diagnosed such that the battery packs (12, 14, 16) whose balance currents (36, 39, 40) have a value of 0 are considered as battery packs with open switches (30, 32, 34), wherein, The diagnostic is performed only when at least one balancing current (36, 39, 40) among the battery packs (12, 14, 16) drops below a critical value, and / or ii) For the disconnect-blocking state (60), at least one switch (30, 32, 34) is diagnosed such that the battery pack (12, 14, 16) identifies a positive diagnosis if a balance current (36, 39, 40) is detected, and on the other hand, if the balance current (36, 39, 40) is not detected, a switch failure is inferred.

2. The method according to claim 1, characterized in that, Before performing step i), at least one switch (30, 32, 34) is checked for the jammed state (58), the current (36, 39, 40) flows in a balanced manner and no current I4 (44) flows toward the vehicle system (48).

3. The method according to claims 1 to 2, characterized in that, According to method step i), the critical value is preferably between 2A and 3A.

4. The method according to claims 1 to 3, characterized in that, In battery packs (12, 14, 16) where the balancing currents (36, 39, 40) are below the critical value, the switches (30, 32, 34) are disconnected such that the relevant balancing currents (36, 39, 40) have a value of 0.

5. The method according to claims 1 to 4, characterized in that, After performing steps i) to ii) of the method and completing the first diagnosis for the stuck state (58) "stuck-closed", perform an additional second diagnosis of the switches (30, 32, 34) for the open-stuck state (60) "stuck-open".

6. The method according to claim 5, characterized in that, Within the framework of the second diagnosis of the switches (30, 32, 34), at least two switches (30, 32, 34) are closed.

7. The method according to claim 6, characterized in that, In the event of a balanced current (36, 39, 40) at one of the battery packs (12, 14, 16) of the relevant switches (30, 32, 34), a disconnection is identified and a positive diagnostic result for the second diagnosis is determined.

8. The method according to claims 5 to 7, characterized in that, In each combination of the switching states (54, 56) of the switches (30, 32, 34), in the case of the absence of balancing current (36, 39, 40), it is deduced that there is an open-blocking state (60) at one of the switches (30, 32, 34).

9. Use of the method according to any one of the preceding claims in a multifunctional system for identifying stuck switches.

10. Use of the method according to any one of claims 1 to 9 in a vehicle system (48) for identifying stuck switches.

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