Battery management system, battery pack and electric device

Abstract

The invention discloses a battery management system, a battery pack and an electric device. The battery management system comprises a first switch, a second switch, a third switch, a voltage sampling module, a first current sampling module, a second current sampling module and a processor. The first switch is electrically connected between the first sampling point and the second sampling point; the second switch is electrically connected between the anode of the first battery and the cathode of the second battery, and the anode of the second battery is electrically connected with the first sampling point; the third switch is electrically connected between the negative electrode of the second battery and the reference point; the voltage sampling module collects the voltage of the first sampling point, the voltage of the second sampling point, the voltage of the first battery and the voltage of the second battery; the first current sampling module collects main loop current; the second current sampling module collects current of a branch where the first battery is located; and the processor is used for determining whether each switch has a fault according to the sampled voltage and current. According to the embodiment of the invention, the accuracy of switch diagnosis can be improved.

Description

[0001] This application is based on the invention with the application number 202510927170.2, the application date is July 7, 2025, the applicant is Ningde Times New Energy Technology Co., Ltd., and the invention name is "Battery Management System, Battery Pack and Electric Device". The invention is a divisional application. TECHNICAL FIELD

[0002] The present application relates to the technical field of battery management, in particular to a battery management system, a battery pack and an electric device. BACKGROUND

[0003] With the development of new energy vehicles, in order to solve the charging anxiety, new energy vehicles are developing towards fast charging 800V system, and the output voltage of some charging piles currently applied is only 400V, which cannot meet the charging requirements of 800V high voltage system.

[0004] In view of this problem, a 400V / 800V switching high voltage topology is proposed in the related technology, which needs to use a switch (such as a relay) to control the series or parallel connection of two batteries. If the switch fails, battery short circuit or failure to achieve charging / discharging may occur, so it is crucial to diagnose the switch failure. SUMMARY

[0005] The present application provides a battery management system, a battery pack and an electric device, which can improve the accuracy of switch fault diagnosis and avoid missed diagnosis.

[0006] In a first aspect, the present application provides a battery management system, comprising a first switch, a second switch, a third switch, a voltage sampling module, a first current sampling module, a second current sampling module and a processor; the first switch is electrically connected between a first sampling point and a second sampling point; the second switch is electrically connected between the positive electrode of a first battery and the negative electrode of a second battery, and the positive electrode of the second battery is electrically connected with the first sampling point; the third switch is electrically connected between the negative electrode of the second battery and a reference point; the voltage sampling module is electrically connected with the first sampling point, the second sampling point, the first battery and the second battery, and is used to collect a first sampling voltage of the first sampling point, a second sampling voltage of the second sampling point, a first battery voltage of the first battery and a second battery voltage of the second battery; the first current sampling module is electrically connected with the reference point, and is used to collect a main loop current; the second current sampling module is electrically connected with a branch in which the first battery is located, and is used to collect a branch current; the processor is connected with the voltage sampling module, the first current sampling module and the second current sampling module, and is used to determine whether the first switch, the second switch and the third switch exist faults according to the first sampling voltage, the second sampling voltage, the first battery voltage, the second battery voltage, the main loop current and the branch current.

[0007] According to the battery management system provided in the embodiments of the present application, the battery management system comprises a first switch, a second switch, a third switch, a voltage sampling module, a first current sampling module, a second current sampling module and a processor. The first switch is electrically connected between a first sampling point and a second sampling point. The second switch is electrically connected between a positive electrode of a first battery and a negative electrode of a second battery, and the positive electrode of the second battery is electrically connected with the first sampling point. The third switch is electrically connected between the negative electrode of the second battery and a reference point. The voltage sampling module is electrically connected with the first sampling point, the second sampling point, the first battery and the second battery, and is configured to collect a first sampling voltage of the first sampling point, a second sampling voltage of the second sampling point, a first battery voltage of the first battery and a second battery voltage of the second battery. The first current sampling module is electrically connected with the reference point, and is configured to collect a main loop current. The second current sampling module is electrically connected with a branch in which the first battery is located, and is configured to collect a branch current. The processor is connected with the voltage sampling module, the first current sampling module and the second current sampling module, and is configured to determine whether the first switch, the second switch and the third switch have faults according to the first sampling voltage, the second sampling voltage, the first battery voltage, the second battery voltage, the main loop current and the branch current. According to the embodiments of the present application, the voltage of the sampling point, the battery voltage and the current value are combined to comprehensively diagnose whether the switch has a fault, which can avoid the risk of misdiagnosis and missed diagnosis caused by invalid single sampling data, improve the diagnosis accuracy, and avoid missed diagnosis.

[0008] In a possible implementation of the first aspect, the battery management system further comprises an active fuse electrically connected between the first sampling point and a third sampling point. The voltage sampling module is further electrically connected with the third sampling point, and is configured to collect a third sampling voltage of the third sampling point. The processor is further configured to determine that the voltage sampling module has a sampling fault in a case where a deviation between the first sampling voltage and the third sampling voltage is greater than a first preset deviation.

[0009] The battery management system provided in the embodiments of the present application can timely and accurately diagnose the sampling fault of the voltage sampling module by adding the active fuse and the third sampling point and the sampling fault diagnosis function of the processor. If the voltage sampling module has a sampling fault, the processor may obtain incorrect voltage data, which affects the judgment of the battery state, the switch state and the like, and even may cause an incorrect control decision, thereby threatening the safety and performance of the battery pack. The fault diagnosis method based on the deviation between the first sampling voltage and the third sampling voltage can effectively improve the reliability and safety of the battery management system.

[0010] In one possible implementation of the first aspect, the processor is further configured to: use the third sampling voltage to replace the first sampling voltage for switching fault diagnosis when the voltage sampling module cannot acquire the first sampling voltage but can acquire the third sampling voltage.

[0011] This application employs a substitution diagnostic mechanism. When the voltage sampling module experiences a sampling failure in the first sampling voltage, a third sampling voltage is used to replace the first sampling voltage for switch fault diagnosis, ensuring that switch fault diagnosis can still be performed. In actual operation, the voltage sampling module may fail to acquire the first sampling voltage due to various reasons (such as sensor failure, poor wiring contact, etc.). Without a substitution diagnostic mechanism, the system would be unable to diagnose switch faults, thus affecting the safe operation of the battery pack. With this mechanism, the system can continue fault diagnosis even when the first sampling voltage acquisition is abnormal, promptly detecting switch faults and avoiding potential safety hazards.

[0012] In one possible implementation of the first aspect, the processor is further configured to: If the voltage sampling module cannot acquire the second sampling voltage but can acquire the first battery voltage, the first battery voltage is used to replace the second sampling voltage for diagnosing the switch fault.

[0013] This application employs a substitution diagnostic mechanism. When the voltage sampling module experiences a sampling failure in the second sampling voltage, the first battery voltage is used instead of the second sampling voltage for switch fault diagnosis, ensuring that switch fault diagnosis can still be performed. In actual operation, the voltage sampling module may fail to acquire the second sampling voltage for various reasons. Without a substitution diagnostic mechanism, the system would be unable to diagnose switch faults, thus affecting the safe operation of the battery pack. With this mechanism, the system can continue fault diagnosis even when the second sampling voltage acquisition is abnormal, promptly detecting switch faults and avoiding potential safety hazards.

[0014] In one possible implementation of the first aspect, the processor is used to: If the first sampling voltage is greater than the first threshold when the first switch, the second switch, and the third switch are all open, it is determined that at least one of the first switch, the second switch, and the third switch has an adhesion fault.

[0015] The processor in this application embodiment can determine whether there is a switch sticking fault by judging whether the first sampling voltage is greater than the first threshold when the first switch, the second switch and the third switch are all open. This provides an effective switch sticking fault diagnosis mechanism and ensures the safety and reliability of the battery management system.

[0016] In one possible implementation of the first aspect, the processor is used to: If the first switch, the second switch, and the third switch are all open, and at least one of the following three relationships is satisfied, then it is determined that the first switch or the third switch has an adhesion fault. |U1-U2|≤a1*U2; |U1-VM1|≤a1*VM1; |U1-VM2|≤a1*VM2; U1 represents the first sampling voltage, U2 represents the second sampling voltage, VM1 represents the first battery voltage, VM2 represents the second battery voltage, and a1 is a preset value less than 0.5.

[0017] This application's embodiments limit the difference ratio, for example, by limiting |U1. U2∣、∣U1 VM1 | ∣, | U1 The proportional relationship between VM2| and the corresponding voltage can accurately determine whether there is a sticking fault in the first or third switch. Since the fault can be determined when at least one of the above relationships is satisfied, the robustness of the diagnosis is improved.

[0018] In one possible implementation of the first aspect, the processor is further configured to: If |U1-VM1| < |U1-VM2|, then the first switch is determined to have a sticking fault.

[0019] This application embodiment compares |U1 VM1|and|U1 The size of VM2| can directly determine whether the first switch has a sticking fault, thus improving the efficiency of fault diagnosis.

[0020] In one possible implementation of the first aspect, the processor is further configured to: If |U1-VM1|>|U1-VM2|, then the third switch is determined to have a sticking fault.

[0021] This application embodiment compares |U1 VM1|and|U1 The size of VM2| can directly determine whether there is a sticking fault in the third switch, thus improving the efficiency of fault diagnosis.

[0022] In one possible implementation of the first aspect, the processor is used to: If the first switch, the second switch, and the third switch are all open, and at least one of the following two relationships is satisfied, then the second switch is determined to have an adhesion fault. |U1-2*U2|≤a2*2*U2; |U1-(VM1+VM2)|≤a2*(VM1+VM2); U1 represents the first sampling voltage, U2 represents the second sampling voltage, VM1 represents the first battery voltage, VM2 represents the second battery voltage, and a2 is a preset value less than 0.5.

[0023] The embodiments of this application can directly determine whether the second switch has an adhesion fault by judging the above relationship, thereby improving the efficiency of fault diagnosis.

[0024] In one possible implementation of the first aspect, the battery management system further includes a main circuit switch, the processor being configured to: If U1≤b1*U2, and the first switch is closed while the second switch, the third switch, and the main circuit switch are open, then the first switch is determined to have an open circuit fault. U1 represents the first sampling voltage, U2 represents the second sampling voltage, and b1 is a preset value less than 0.5.

[0025] The embodiments of this application can promptly diagnose open-circuit faults in the first switch, thereby ensuring the independent and normal charging of the first battery.

[0026] In one possible implementation of the first aspect, the battery management system further includes a main circuit switch, the processor being configured to: If U1≤b1*U2, and the third switch is closed while the first switch, the second switch, and the main circuit switch are open, then the third switch is determined to have an open circuit fault. U1 represents the first sampling voltage, U2 represents the second sampling voltage, and b1 is a preset value less than 0.5.

[0027] The embodiments of this application can promptly diagnose open-circuit faults in the third switch, thereby ensuring the independent and normal charging of the second battery.

[0028] In one possible implementation of the first aspect, the battery management system further includes a main circuit switch, the processor being configured to: If U1≤b1*U2, and the first and third switches are closed while the second and main circuit switches are open, then the first and third switches are determined to have an open circuit fault. U1 represents the first sampling voltage, U2 represents the second sampling voltage, and b1 is a preset value less than 0.5.

[0029] The embodiments of this application can promptly diagnose open-circuit faults in the first and third switches, thereby ensuring that the first and second batteries can be charged in parallel normally.

[0030] In one possible implementation of the first aspect, the battery management system further includes a main circuit switch, the processor being configured to: If the first switch and the main circuit switch are closed and the second switch is open, then the first switch is determined to have an open circuit fault if at least one of the following two relationships is satisfied. U1≤b1*U2; |Shunt2|≤I1 and |Shunt1|≥I2; U1 represents the first sampling voltage, U2 represents the second sampling voltage, Shunt1 represents the main circuit current, Shunt2 represents the branch current, b1 is a preset value less than 0.5, I1 and I2 are preset values, and I1 < I2.

[0031] This application embodiment, by combining voltage and current sampling data for comprehensive judgment, can more accurately diagnose whether the first switch has an open circuit fault. Furthermore, the redundant fault diagnosis mechanism improves the reliability of the system and can ensure timely detection and handling when the first switch has an open circuit fault.

[0032] In one possible implementation of the first aspect, the battery management system further includes a main circuit switch, the processor being configured to: If the third switch and the main circuit switch are closed and the second switch is open, then the third switch is determined to have an open circuit fault if at least one of the following two relationships is satisfied. U1≤b2*U2; |Shunt1-Shunt2|≤b2*Shunt1 and |Shunt1|≥I2; U1 represents the first sampling voltage, Shunt1 represents the main circuit current, Shunt2 represents the branch current, b2 is a preset value less than 0.5, and I2 is a preset value.

[0033] This application embodiment uses a combination of voltage and current sampling data for comprehensive judgment, which can more accurately diagnose whether there is an open circuit fault in the third switch. Furthermore, the redundant fault diagnosis mechanism improves the reliability of the system and ensures that an open circuit fault in the third switch can be detected and dealt with in a timely manner.

[0034] In one possible implementation of the first aspect, the processor is used to: If U1≤b3*U2, and the first and third switches are open while the second switch is closed, then the second switch is determined to have an open circuit fault. U1 represents the first sampling voltage, U2 represents the second sampling voltage, and b3 is a preset value less than 0.5.

[0035] The embodiments of this application can promptly diagnose open-circuit faults in the second switch, thereby ensuring that the first battery and the second battery can be charged / discharged in series normally.

[0036] In one possible implementation of the first aspect, the processor is further configured to: When the output voltage of the charging device electrically connected to the battery management system is greater than the threshold voltage, the second switch is closed, while the first and third switches are open.

[0037] In this embodiment, when the output voltage of the charging device is greater than the threshold voltage, a series charging mode of the first battery and the second battery is adopted. The battery pack (the first battery and the second battery) can make full use of the high output voltage of the charging device (such as 800V high voltage), reduce charging time, and improve charging efficiency.

[0038] In one possible implementation of the first aspect, the processor is further configured to: When the output voltage of the charging device electrically connected to the battery management system is less than the threshold voltage, if |VM1-VM2|≤V1, the first and third switches are closed, and the second switch is open. VM1 represents the first battery voltage, VM2 represents the second battery voltage, and V1 is a preset value.

[0039] This application embodiment describes a charging strategy for a battery management system when the output voltage of the charging device is less than a threshold voltage. For example, if the output voltage of the charging device is 400V, a parallel charging mode can be adopted. Before entering the parallel charging mode, it can also determine whether the difference between the first battery voltage VM1 and the second battery voltage VM2 is small enough, so as to ensure that the voltage difference between the two batteries is not too large during parallel charging, thereby avoiding current imbalance and potential battery damage, and ensuring the safety and reliability of the charging process.

[0040] In one possible implementation of the first aspect, the processor is further configured to: If the output voltage of the charging device connected to the battery management system is less than the threshold voltage, and VM1-VM2>V1, the third switch is closed first, while the first and second switches are open. The charging current Ia is requested until the voltage difference between the second battery and the first battery is less than V2. The first switch is closed after the charging current drops below Ia. VM1 represents the first battery voltage, VM2 represents the second battery voltage, V1 and V2 are preset values, and V2 < V1, Ia is the current safety threshold.

[0041] This application describes a charging strategy for a battery management system when the output voltage of the charging device is less than a threshold voltage and the voltage difference between the first and second batteries is large (VM1-VM2>V1). By first charging the battery with the lower voltage (such as the second battery) individually, and then gradually charging them in parallel, the risk of excessive current or battery damage caused by voltage imbalance is avoided. This ensures safe and efficient charging of the battery pack under voltage imbalance conditions, ultimately achieving voltage balance. Furthermore, a current safety threshold Ia is set during the charging process to avoid the impact of large currents on the battery, ensuring the safety and reliability of the charging process and extending the battery's lifespan.

[0042] In one possible implementation of the first aspect, the processor is further configured to: When the output voltage of the charging device connected to the battery management system is less than the threshold voltage, if VM2-VM1>V1, the first switch is closed first, and the third and second switches are open until the voltage of the first battery is charged to the point where the voltage difference with the second battery is less than V2. Then the charging current Ia is requested until the charging current drops below Ia. Then the third switch is closed. VM1 represents the first battery voltage, VM2 represents the second battery voltage, V1 and V2 are preset values, and V2 < V1, Ia is the current safety threshold.

[0043] This application describes a charging strategy for a battery management system when the output voltage of the charging device is less than a threshold voltage and the voltage difference between the first and second batteries is large (VM1-VM2>V1). By first charging the battery with the lower voltage (such as the first battery) individually and then gradually charging them in parallel, the risk of excessive current or battery damage caused by voltage imbalance is avoided. This ensures safe and efficient charging of the battery pack under voltage imbalance conditions, ultimately achieving voltage balance. Furthermore, a current safety threshold Ia is set during the charging process to avoid the impact of large currents on the battery, ensuring the safety and reliability of the charging process and extending the battery's lifespan.

[0044] In one possible implementation of the first aspect, the battery management system further includes: The first fuse is connected in series with the first switch between the first sampling point and the second sampling point; And / or, a second fuse, connected in series with a third switch between the negative terminal of the second battery and a reference point.

[0045] In this embodiment, a newly added first fuse and a first switch are connected in series between the first sampling point and the second sampling point. When the current flowing through the first fuse exceeds its rated value, the fuse wire inside the first fuse will melt due to overheating, thereby cutting off the circuit and preventing equipment damage caused by excessive current. A newly added second fuse and a third switch are connected in series between the negative terminal of the second battery and the reference point. When the current flowing through the second fuse exceeds its rated value, the fuse wire inside the second fuse will melt due to overheating, thereby cutting off the circuit and preventing equipment damage caused by excessive current.

[0046] Based on the same inventive concept, in a second aspect, embodiments of this application provide a battery pack including a first battery, a second battery, and a battery management system as described in any embodiment of the first aspect.

[0047] The battery pack provided in this application includes the battery management system in any of the above embodiments, and therefore the battery pack has the beneficial effects of the battery management system provided in any of the above embodiments.

[0048] Based on the same inventive concept, in a third aspect, embodiments of this application provide an electrical device including a battery pack as described in any embodiment of the first aspect.

[0049] The power device provided in this application includes a battery pack, which includes the battery management system in any of the above embodiments. Therefore, the power device has the beneficial effects of the battery management system provided in any of the above embodiments.

[0050] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0051] The features, advantages, and technical effects of exemplary embodiments of this application will now be described with reference to the accompanying drawings.

[0052] Figure 1 This is a schematic diagram of the structure of a battery management system according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a battery management system according to another embodiment of this application; Figure 3 This is a schematic diagram of the structure of a battery management system according to another embodiment of this application; Figure 4 This is a schematic diagram of the structure of a battery management system according to another embodiment of this application; Figure 5 This is a schematic diagram of the structure of a battery management system according to another embodiment of this application; Figure 6 This is a schematic diagram of the charging process of a battery management system according to a scenario embodiment of this application; Figure 7 This is a schematic diagram of the structure of a battery pack according to an embodiment of this application; Figure 8 This is a schematic diagram of the structure of an electrical device according to an embodiment of this application. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0054] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0055] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0056] Before describing the technical solutions provided in the embodiments of this application, in order to facilitate understanding of the embodiments of this application, this application first specifically explains the problems existing in the related technologies: With the rapid development of the new energy vehicle industry, the component industry of 800V high-voltage architecture has matured. For example, high-voltage components such as motors, inverters, on-board chargers (OBC), DC-DC converters (DCDC), and air conditioning compressors are all capable of supporting the operation of 800V systems.

[0057] Increasing the voltage platform can improve work efficiency, reduce vehicle energy consumption, and increase driving range. At the same time, a high voltage platform can also improve charging speed.

[0058] Currently, most new energy vehicles use an 800V voltage platform. However, due to the relatively slow pace of charging pile upgrades in some areas, some charging piles are still 400V, resulting in a voltage mismatch between the charging pile and the vehicle, which poses a challenge to charging new energy vehicles.

[0059] To address the issue of charging 800V battery packs with 400V charging stations, related technologies employ DC-DC boost modules or multiplexed inverters as the boost module solution. However, this solution has the following drawbacks: Limited charging power: DC-DC booster modules and inverters themselves have certain power limits, restricting charging power and making it impossible to meet the demand for high-rate charging. High-rate charging is crucial for shortening charging time and improving user experience, but the current technology cannot meet this requirement, limiting further improvements in the charging efficiency of new energy vehicles.

[0060] Increased costs: Because bypassing the DC-DC booster module and inverter is required, an additional boost relay is needed to control the bypass. This not only increases hardware costs but also makes the system structure more complex, increasing the probability of failure and maintenance costs.

[0061] In view of this, related technologies have proposed a high-voltage topology with 400V / 800V switching, which requires a switch (such as a relay) to control the series or parallel connection of the two batteries. For example, two 400V battery packs are connected in parallel during charging to adapt to 400V charging stations; during discharging, they are connected in series to achieve an output voltage of 800V to meet the power requirements of vehicle operation.

[0062] Because switches (such as relays) are needed to control the connection method of the battery pack, timely detection of switch malfunctions is crucial to ensuring the safe operation of the battery pack. For example, a switch sticking together may cause a short circuit in the battery, leading to serious consequences such as overheating, fire, or even explosion; while a switch open circuit may prevent the battery from charging and discharging properly, affecting the normal use of the vehicle.

[0063] Based on this, embodiments of this application provide a battery management system, a battery pack, and an electrical device. By combining the sampling point voltage, battery voltage, and current value, it is possible to comprehensively diagnose whether a switch is faulty. This avoids the risk of single sampling failure, improves diagnostic accuracy, and avoids missed diagnoses.

[0064] The battery management system provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0065] Figure 1 This is a schematic diagram of the structure of a battery management system provided in an embodiment of this application, such as... Figure 1 As shown, the battery management system 100 may include a first switch 10, a second switch 20, a third switch 30, a voltage sampling module 40, a first current sampling module 50, a second current sampling module 60, and a processor 70.

[0066] The first switch 10 is electrically connected between the first sampling point S1 and the second sampling point S2.

[0067] The second sampling point S2 is electrically connected to the positive electrode of the first battery 200.

[0068] Specifically, the first switch 10 is located between the first sampling point S1 and the second sampling point S2. Therefore, the change in the state of the first switch 10 will directly affect the electrical connection between the first sampling point S1 and the second sampling point S2.

[0069] The second switch 20 is electrically connected between the positive terminal of the first battery 200 and the negative terminal of the second battery 300. The positive terminal of the second battery 300 is electrically connected to the first sampling point S1.

[0070] Specifically, the second switch 20 is positioned between the two batteries (the first battery 200 and the second battery 300), so the second switch 20 can control the connection between the first battery 200 and the second battery 300.

[0071] The third switch 30 is electrically connected between the negative terminal of the second battery 300 and the reference point G.

[0072] Among them, reference point G can be the reference location for high-pressure sampling.

[0073] Specifically, the third switch 30 is located between the negative terminal of the second battery 300 and the reference point G, so the state of the third switch 30 will affect the electrical connection between the second battery 300 and the reference point G.

[0074] For example, the first switch 10, the second switch 20, and the third switch 30 can be relays or other types of switches.

[0075] By controlling the states of the first switch 10, the second switch 20, and the third switch 30, the battery management system 100 can switch between the following four operating modes: 1) Series 800V charging / discharging mode.

[0076] With the first switch 10 and the third switch 30 open and the second switch 20 closed, the first battery 200 and the second battery 300 are connected in series. For example, it can be used to power the 800V high-voltage components of the vehicle; or an 800V charging device can be used to charge the first battery 200 and the second battery 300.

[0077] 2) Parallel 400V charging mode.

[0078] When the first switch 10 and the third switch 30 are closed and the second switch 20 is open, the first battery 200 and the second battery 300 are connected in parallel.

[0079] For example, such as Figure 2 As shown, the first sampling point S1 is electrically connected to the positive terminal P+, and the reference point G is electrically connected to the negative terminal p-. The positive terminal P+ and the negative terminal p- are respectively electrically connected to the positive and negative terminals of the 400V charging device, so that the first battery 200 and the second battery 300 can be charged using the 400V charging device.

[0080] 3) The first battery 200V is charged separately in 400V charging mode.

[0081] With the first switch 10 closed and the second switch 20 and the third switch 30 open, the first battery 200 can be charged separately using a 400V charging device.

[0082] 4) Second battery 300V independent 400V charging mode.

[0083] With the third switch 30 closed and the first switch 10 and the second switch 20 open, the second battery 300 can be charged separately using a 400V charging device.

[0084] The voltage sampling module 40 is electrically connected to the first sampling point S1, the second sampling point S2, the first battery 200, and the second battery 300, and is used to collect the first sampling voltage of the first sampling point S1, the second sampling voltage of the second sampling point S2, the first battery voltage of the first battery 200, and the second battery voltage of the second battery 300.

[0085] Specifically, the voltage sampling module 40 can be used for voltage sampling, such as collecting the first sampling voltage at the first sampling point S1, the second sampling voltage at the second sampling point S2, the first battery voltage of the first battery 200, and the second battery voltage of the second battery 300.

[0086] When the first battery 200 comprises multiple cells connected in series, the first battery voltage of the first battery 200 can be the sum of the voltages of the multiple cells in the first battery. When the second battery 300 comprises multiple cells connected in series, the second battery voltage of the second battery 300 can be the sum of the voltages of the multiple cells in the second battery.

[0087] The first current sampling module 50 is electrically connected to the reference point G and is used to collect the main circuit current.

[0088] Here, the main circuit represents the output circuit of the first battery and the second battery, that is, the connection path between the positive terminal P+ and the negative terminal P-, and the main circuit current represents the current in the connection path between the positive terminal P+ and the negative terminal P-.

[0089] With the first switch 10 and the third switch 30 open and the second switch 20 closed, the first battery 200 and the second battery 300 are connected in series on the connection path between the positive terminal P+ and the negative terminal P-.

[0090] When the first switch 10 and the third switch 30 are closed and the second switch 20 is open, the first battery 200 and the second battery 300 are connected in parallel on the connection path between the positive terminal P+ and the negative terminal P-.

[0091] When the first switch 10 is closed and the second switch 20 and the third switch 30 are open, the first battery 200 is connected to the connection path between the positive terminal P+ and the negative terminal P-, while the second battery 300 is not connected to the connection path between the positive terminal P+ and the negative terminal P-.

[0092] When the third switch 30 is closed and the first switch 10 and the second switch 20 are open, the second battery 300 is connected to the connection path between the positive terminal P+ and the negative terminal P-, while the first battery 200 is not connected to the connection path between the positive terminal P+ and the negative terminal P-.

[0093] When the switch malfunctions, it may cause abnormal current in the main circuit. The first current sampling module 50 can capture the changes in the main circuit current in a timely manner.

[0094] The second current sampling module 60 is electrically connected to the branch where the first battery 200 is located, and is used to collect the branch current.

[0095] Among them, the branch current mainly reflects the current situation of the branch where the first battery 200 is located.

[0096] Specifically, by coordinating the current in the branch where the first battery 200 is located with the current in the main circuit, a more comprehensive understanding of the current distribution of the battery management system and the impact of switching on the current can be obtained.

[0097] The processor 70 is connected to the voltage sampling module 40, the first current sampling module 50, and the second current sampling module 60, and is used to determine whether the first switch 10, the second switch 20, and the third switch 30 are faulty based on the first sampling voltage, the second sampling voltage, the first battery voltage, the second battery voltage, the main circuit current, and the branch current.

[0098] The processor 70 is the core control unit of the entire battery management system 100. The processor 70 includes, but is not limited to, a microcontroller unit (MCU).

[0099] The processor 70 can perform a comprehensive diagnosis of whether the first switch 10, the second switch 20, and the third switch 30 are faulty based on various sampling data, including the first sampling voltage, the second sampling voltage, the first battery voltage, the second battery voltage, the main circuit current, and the branch current. For example, the processor 70 can compare the voltage values ​​at different sampling points and the battery voltage, combined with the changes in current, to determine whether the switches are stuck or open-circuited. This avoids the risk of misdiagnosis or missed diagnosis caused by the failure of a single sampling data point, thus improving the accuracy of diagnosis and preventing missed diagnoses.

[0100] According to the battery management system 100 provided in the embodiments of this application, the battery management system 100 includes a first switch 10, a second switch 20, a third switch 30, a voltage sampling module 40, a first current sampling module 50, a second current sampling module 60, and a processor 70. The first switch 10 is electrically connected between a first sampling point S1 and a second sampling point S2. The second switch 20 is electrically connected between the positive terminal of a first battery 200 and the negative terminal of a second battery 300, with the positive terminal of the second battery 300 electrically connected to the first sampling point S1. The third switch 30 is electrically connected between the negative terminal of the second battery 300 and a reference point G. The voltage sampling module 40 is electrically connected to the first sampling point S1, the second sampling point S2, the first battery 200, and the second battery 300, and is used to collect the first sampling voltage of the first sampling point S1, the second sampling voltage of the second sampling point S2, the first battery voltage of the first battery 200, and the second battery voltage of the second battery 300. The first current sampling module 50 is electrically connected to the reference point G and is used to collect the main circuit current. The second current sampling module 60 is electrically connected to the branch where the first battery 200 is located and is used to collect the branch current. The processor 70 is connected to the voltage sampling module 40, the first current sampling module 50, and the second current sampling module 60, and is used to determine whether the first switch 10, the second switch 20, and the third switch 30 are faulty based on the first sampling voltage, the second sampling voltage, the first battery voltage, the second battery voltage, the main circuit current, and the branch current. This embodiment of the application combines the sampling point voltage, battery voltage, and current value to comprehensively diagnose whether the switches are faulty, which can avoid the risk of misdiagnosis and missed diagnosis caused by the failure of a single sampling data, improve the accuracy of diagnosis, and avoid missed diagnosis.

[0101] It should be noted that, according to the inventors' research, related technologies are basically based on the voltage across the relay for relay sticking diagnosis. Each relay requires sampling points at both ends, resulting in a large number of sampling points. Furthermore, if the voltage at the sampling points is not collected or is inaccurate, it can easily lead to misdiagnosis or missed diagnosis. In contrast, the embodiments of this application do not require sampling points at each switch end, reducing the number of sampling points. Moreover, by combining the voltage at the sampling points, battery voltage, and current value, a comprehensive diagnosis of whether the switch is faulty can be performed. This avoids misdiagnosis or missed diagnosis caused by the inability to collect voltage data at both ends of the switch or inaccurate voltage data collection, avoids the risk of single sampling data failure, and improves diagnostic accuracy.

[0102] Figure 3 This is another structural schematic diagram of the battery management system 100 provided in the embodiments of this application.

[0103] In some embodiments, such as Figure 3 As shown, the battery management system 100 may also include an active fuse 81, which is electrically connected between the first sampling point S1 and the third sampling point S3.

[0104] The voltage sampling module 40 is also electrically connected to the third sampling point S3 to collect the third sampling voltage of the third sampling point S3.

[0105] The processor 70 is also configured to: determine that the voltage sampling module 40 has a sampling fault if the deviation between the first sampling voltage and the third sampling voltage is greater than a first preset deviation.

[0106] Among them, the active fuse 81 is an electrical component with active protection function. For example, when the current sampling module detects an abnormal current, the processor 70 can trigger the active fuse to operate, promptly cutting off the circuit and protecting the battery pack and other electrical components from damage. As the active fuse of the main circuit, in the event of an emergency (such as a collision, thermal runaway, or other extreme conditions), the processor 70 can drive the active fuse 81 to actively disconnect the high-voltage circuit, preventing the spread of harm.

[0107] Voltage relationship under normal conditions: When the battery management system 100 is operating normally, since the first sampling point S1 and the third sampling point S3 are connected by the active fuse 81, and under fault-free conditions, the resistance of the active fuse 81 is relatively small, its impact on the voltage can be ignored. Therefore, the first sampling voltage of the first sampling point S1 and the third sampling voltage of the third sampling point S3 should theoretically be similar, that is, the deviation between the two should be within a small range.

[0108] Sampling fault judgment conditions: The processor 70 will preset a first preset deviation value. When the deviation between the first sampling voltage and the third sampling voltage is greater than this first preset deviation, it means that the voltage sampling module 40 may have encountered a problem when collecting the voltage of the first sampling point S1 and the third sampling point S3, that is, there is a sampling fault. At this time, the battery management system 100 can report the fault and will not respond to the vehicle's high voltage command (because it cannot distinguish which sampling point, the first sampling point S1 or the third sampling point S3, has a sampling problem).

[0109] The first preset deviation value and other preset values ​​mentioned below can be set according to the actual situation, but this application does not limit them.

[0110] The battery management system 100 provided in this application embodiment can promptly and accurately diagnose sampling faults in the voltage sampling module 40 by adding an active fuse 81, a third sampling point S3, and a sampling fault diagnosis function to the processor 70. If the voltage sampling module 40 has a sampling fault, it may cause the processor 70 to obtain incorrect voltage data, thereby affecting the judgment of battery status, switch status, etc., and may even lead to incorrect control decisions, such as misjudging battery overcharge or over-discharge, thus threatening the safety and performance of the battery pack. Through this fault diagnosis method based on the deviation between the first and third sampling voltages, the reliability and safety of the battery management system 100 can be effectively improved.

[0111] In one example, the voltage sampling module may include multiple analog-to-digital converters (ADCs). Different sampling points can use different ADCs, and configuring independent ADC channels for different sampling points can prevent multiple voltage signals from failing simultaneously due to a single ADC failure, thus improving the system's fault tolerance and stability. For the battery voltages of the first and second batteries, analog front-end (AFE) sampling can be used. An AFE is an integrated chip used for battery signal acquisition. Utilizing the integrated advantages of analog front-end AFE sampling, high-precision and high-reliability battery voltage monitoring can be achieved. These two different sampling schemes can avoid the risk of a single failure.

[0112] The following describes the specific process by which the battery management system 100 provided in this application improves the robustness of the entire strategy by using an alternative diagnostic mechanism.

[0113] In some embodiments, the processor 70 can also be used to: replace the first sampling voltage with the third sampling voltage to diagnose the switch fault when the voltage sampling module 40 cannot collect the first sampling voltage but can collect the third sampling voltage.

[0114] The active fuse 81 is equivalent to a very small resistor. Under normal operation, the voltages at the first sampling point S1 and the third sampling point S3 can be approximated as equal.

[0115] During the operation of the battery management system 100, the processor 70 continuously monitors the voltage sampling module 40's acquisition of voltage at each sampling point. When the voltage sampling module 40 fails to acquire the first sampling voltage but can acquire the third sampling voltage, the processor 70 will activate the voltage substitution diagnostic mechanism, that is, use the third sampling voltage to replace the first sampling voltage for switching fault diagnosis.

[0116] It should be noted that after replacing the first sampling voltage with the third sampling voltage, the processor 70 needs to adjust the logic for switch fault diagnosis. The original algorithm, which was based on the first sampling voltage and other voltage and current data for fault judgment, needs to be modified to be based on the third sampling voltage and other relevant data.

[0117] It should also be noted that this alternative diagnostic mechanism is part of the data redundancy and fault-tolerant design of the battery management system 100. By adding a third sampling point S3 and collecting its voltage, the system can utilize the third sampling voltage to ensure the continuity and accuracy of switch fault diagnosis when the voltage collection at the first sampling point S1 is abnormal. Just as in a data backup system, when the primary data source fails, the backup data source can take over in time to ensure the normal operation of the system, in the battery management system 100, the third sampling voltage is equivalent to a backup data source, which can play a role when the first sampling voltage is unavailable. The redundant switch diagnostic scheme (alternative diagnostic mechanism) provided in this application embodiment can ensure the accuracy of switch diagnosis and avoid missed detections.

[0118] This application embodiment employs a substitution diagnostic mechanism. When the voltage sampling module 40 experiences a sampling failure in the first sampling voltage, a third sampling voltage is used to replace the first sampling voltage for switch fault diagnosis, ensuring the accuracy of the switch fault diagnosis. In actual operation, the voltage sampling module 40 may fail to acquire the first sampling voltage due to various reasons (such as sensor failure, poor wiring contact, etc.). Without a substitution diagnostic mechanism, the system would be unable to perform switch fault diagnosis, thus affecting the safe operation of the battery pack. With this mechanism, the system can continue fault diagnosis when the first sampling voltage acquisition is abnormal, promptly detecting switch faults and avoiding potential safety hazards.

[0119] In some embodiments, the processor 70 may also be used for: If the voltage sampling module 40 cannot collect the second sampling voltage but can collect the first battery voltage, the first battery voltage is used to replace the second sampling voltage for diagnosing the switch fault.

[0120] When an anomaly occurs in the second sampling voltage acquisition, the first battery voltage can be used to ensure the continuity and accuracy of switch fault diagnosis. After replacing the second sampling voltage with the first battery voltage, the processor 70 needs to adjust the switch fault diagnosis logic accordingly. The algorithm that originally judged the fault based on the second sampling voltage and other voltage and current data needs to be modified to judge based on the first battery voltage and other relevant data.

[0121] This application embodiment employs a substitution diagnostic mechanism. When the voltage sampling module 40 experiences a sampling failure in the second sampling voltage, the first battery voltage is used instead of the second sampling voltage for switch fault diagnosis, ensuring the accuracy of the switch fault diagnosis. In actual operation, the voltage sampling module 40 may fail to acquire the second sampling voltage due to various reasons (such as sensor failure, poor line contact, electromagnetic interference, etc.). Without a substitution diagnostic mechanism, the system would be unable to perform switch fault diagnosis, thus affecting the safe operation of the battery pack. With this mechanism, the system can continue fault diagnosis when the second sampling voltage acquisition is abnormal, promptly detecting switch faults and avoiding potential safety hazards.

[0122] The following describes the specific process by which the battery management system 100 provided in this application determines a switch sticking fault.

[0123] The diagnostic timing for switch sticking is before issuing a closing command to the switch or after issuing an opening command to the switch.

[0124] In some embodiments, the processor 70 may be used for: If the first sampling voltage is greater than the first threshold when the first switch 10, the second switch 20 and the third switch 30 are all open, it is determined that at least one of the first switch 10, the second switch 20 and the third switch 30 has an adhesion fault.

[0125] Specifically, under normal circumstances, when the first switch 10, the second switch 20, and the third switch 30 are all open, the first sampling voltage of the first sampling point S1 should theoretically be in a relatively low voltage state (such as zero voltage or a small voltage). When at least one of the first switch 10, the second switch 20, or the third switch 30 experiences a sticking fault, it will cause a connection between the first sampling point S1 and the reference point G, and the connection path between the first sampling point S1 and the reference point G includes at least one of the first battery and the second battery, causing the voltage of the first sampling point S1 to rise. Therefore, when the first sampling voltage of the first sampling point S1 is greater than a preset first threshold, it indicates that at least one of the first switch 10, the second switch 20, and the third switch 30 has a sticking fault.

[0126] The processor 70 in this embodiment can determine whether there is a switch sticking fault by judging whether the first sampling voltage is greater than the first threshold when the first switch 10, the second switch 20 and the third switch 30 are all off. This provides an effective switch sticking fault diagnosis mechanism and ensures the safety and reliability of the battery management system 100.

[0127] In some embodiments, the processor 70 may be used for: If the first switch 10, the second switch 20, and the third switch 30 are all open, and at least one of the following three relationships is satisfied, then it is determined that the first switch 10 or the third switch 30 has an adhesion fault.

[0128] |U1-U2|≤a1*U2; |U1-VM1|≤a1*VM1; |U1-VM2|≤a1*VM2; U1 represents the first sampling voltage, U2 represents the second sampling voltage, VM1 represents the first battery voltage, VM2 represents the second battery voltage, and a1 is a preset value less than 0.5.

[0129] Specifically, if the first switch 10 is stuck, the first sampling point S1 will be connected to the first battery 200 through the stuck first switch 10, resulting in a smaller difference between U1 and VM1 or U1 and U2. If the third switch 30 is stuck, the first sampling point S1 will be connected to the second battery 300 through the stuck third switch 30, resulting in a smaller difference between U1 and VM2. Therefore, when the first switch 10, the second switch 20, and the third switch 30 are all in the off state, if at least one of the above three relationships is satisfied, the processor 70 can determine that the first switch 10 or the third switch 30 has a sticking fault.

[0130] a1 is a preset value, for example, a1 is 5%. Of course, the size of a1 can be designed according to the actual situation, and this application does not limit it.

[0131] This application's embodiments limit the difference ratio, for example, by limiting |U1. U2∣、∣U1 VM1 | ∣, | U1 The proportional relationship between VM2| and the corresponding voltage can accurately determine whether there is a sticking fault in the first switch 10 or the third switch 30. Since the fault can be determined when at least one of the above relationships is satisfied, the robustness of the diagnosis is improved.

[0132] In some embodiments, the processor 70 may also be used for: If |U1-VM1| < |U1-VM2|, then the first switch 10 is determined to have an adhesion fault.

[0133] Specifically, when the first switch 10, the second switch 20, and the third switch 30 are all open, if the first switch 10 experiences a sticking fault, the first sampling point S1 will form an electrical path with the first battery 200 through the stuck first switch 10. At this time, the value of U1 will be close to VM1, making |U1| close to the value of VM1. The value of VM1| is relatively small. Therefore, when |U1 VM1 | < | U1 When VM2 is used, it can be inferred that the first switch 10 has an adhesion fault.

[0134] This application embodiment compares |U1 VM1|and|U1 The size of VM2| can directly determine whether the first switch 10 has an adhesion fault, thus improving the efficiency of fault diagnosis.

[0135] In some embodiments, the processor 70 may also be used for: If |U1-VM1|>|U1-VM2|, then the third switch 30 is determined to have an adhesion fault.

[0136] Specifically, when the first switch 10, the second switch 20, and the third switch 30 are all open, if the third switch 30 experiences a sticking fault, the first sampling point S1 will form an electrical path with the second battery 300 through the stuck third switch 30, causing |U1| to be unavailable. The value of VM2| is relatively small. Therefore, when |U1-VM1|>|U1-VM2|, it can be determined that the third switch 30 has an adhesion fault.

[0137] This application embodiment compares |U1 VM1|and|U1 The size of VM2| can directly determine whether the third switch 30 has an adhesion fault, thus improving the efficiency of fault diagnosis.

[0138] It should be noted that if |U1-VM1|=|U1-VM2|, then it is impossible to distinguish whether the first switch 10 or the third switch 30 is stuck together, and it can be determined that the first switch 10 or the third switch 30 is stuck together.

[0139] In some embodiments, the processor 70 may be used for: If the first switch 10, the second switch 20, and the third switch 30 are all open, and at least one of the following two relationships is satisfied, then the second switch 20 is determined to have an adhesion fault.

[0140] |U1-2*U2|≤a2*2*U2; |U1-(VM1+VM2)|≤a2*(VM1+VM2); U1 represents the first sampling voltage, U2 represents the second sampling voltage, VM1 represents the first battery voltage, VM2 represents the second battery voltage, and a2 is a preset value less than 0.5.

[0141] Specifically, when the first switch 10, the second switch 20, and the third switch 30 are all in the open state, if the second switch 20 experiences a sticking fault, the first sampling point S1, the second battery 300, the second sampling point S2, and the first battery 200 will form an electrical path based on the sticking second switch 20, that is, the first battery 200 and the second battery 300 will be connected in series. Therefore, if at least one of the above two relationships is satisfied, it can be determined that the second switch 20 has a sticking fault.

[0142] a2 is a preset value, for example, a2 is 5%. Of course, the size of a2 can be designed according to the actual situation, and this application does not limit it.

[0143] The embodiments of this application can directly determine whether the second switch 20 has an adhesion fault by determining the above-mentioned relationship, thereby improving the efficiency of fault diagnosis.

[0144] The above is an introduction to the diagnostic solution for switch adhesion.

[0145] The following describes the specific process of determining an open-circuit fault in the battery management system 100 provided in this application embodiment.

[0146] The timing for diagnosing an open circuit in a switch is either before issuing an open command to the switch or after issuing a close command to the switch.

[0147] Figure 4 This is another structural schematic diagram of the battery management system 100 provided in the embodiments of this application.

[0148] In some embodiments, such as Figure 4 As shown, the battery management system 100 may also include a main circuit switch 82, and the processor 70 may be used for: If U1≤b1*U2, and the first switch 10 is closed while the second switch 20, the third switch 30, and the main circuit switch 82 are open, then the first switch 10 is determined to have an open circuit fault.

[0149] U1 represents the first sampling voltage, U2 represents the second sampling voltage, and b1 is a preset value less than 0.5 (e.g., 0.4).

[0150] Specifically, when the first switch 10 is normally closed and all other switches are open, it is equivalent to the first battery 200 being charged at 400V alone. Theoretically, the first sampling point S1 should be electrically connected to the first battery 200 through the first switch 10. If the first switch 10 has an open circuit fault, although the control signal indicates that it is closed, there is actually no electrical connection between the first sampling point S1 and the first battery 200. Therefore, if U1≤b1*U2, it can be determined that the first switch 10 has an open circuit fault.

[0151] The embodiments of this application can promptly diagnose open-circuit faults in the first switch 10, thereby ensuring that the first battery 200 can be charged normally at 400V.

[0152] It should be noted that the accompanying drawings illustrate the connection of the positive terminal P+ to the main circuit switch 82, but this is not intended to limit the scope of this application. For example, in other examples, the positive terminal P+ and the negative terminal P- are each connected to the main circuit switch 82, or the negative terminal P- is connected to the main circuit switch 82.

[0153] In some embodiments, see [link to relevant documentation]. Figure 4 The battery management system 100 may also include a main circuit switch 82, and the processor 70 may be used for: If U1≤b1*U2, and the third switch 30 is closed while the first switch 10, the second switch 20, and the main circuit switch 82 are open, then the third switch 30 is determined to have an open circuit fault.

[0154] U1 represents the first sampling voltage, U2 represents the second sampling voltage, and b1 is a preset value less than 0.5.

[0155] Specifically, when the third switch 30 is normally closed and all other switches are open, it is equivalent to the second battery 300 being charged at 400V alone. Theoretically, the first sampling point S1 should be electrically connected to the second battery 300 through the third switch 30. If the third switch 30 has an open circuit fault, although the control signal indicates that it is closed, there is actually no electrical connection between the first sampling point S1 and the second battery 300. Therefore, if U1≤b1*U2, it can be determined that the third switch 30 has an open circuit fault.

[0156] The embodiments of this application can promptly diagnose open-circuit faults in the third switch 30, thereby ensuring that the second battery 300 can be charged normally at 400V.

[0157] In some embodiments, see [link to relevant documentation]. Figure 4 The battery management system 100 may also include a main circuit switch 82, and the processor 70 may be used for: If U1≤b1*U2, and the first switch 10 and the third switch 30 are closed while the second switch 20 and the main circuit switch 82 are open, then it is determined that the first switch 10 and the third switch 30 have an open circuit fault.

[0158] U1 represents the first sampling voltage, U2 represents the second sampling voltage, and b1 is a preset value less than 0.5.

[0159] Specifically, when the first switch 10 and the third switch 30 are normally closed, and the other switches are open, it is equivalent to a parallel 400V charging mode. Theoretically, the first sampling point S1 should be electrically connected to the first battery 200 through the first switch 10, and the first sampling point S1 should be electrically connected to the second battery 300 through the third switch 30. If both the first switch 10 and the third switch 30 have open circuit faults, although the control signal indicates that they are closed, there is actually no electrical connection between the first sampling point S1 and the first battery 200, nor between the first sampling point S1 and the second battery 300. Therefore, if U1≤b1*U2, it can be determined that the first switch 10 and the third switch 30 have open circuit faults.

[0160] The embodiments of this application can promptly diagnose open-circuit faults in the first switch 10 and the third switch 30, thereby ensuring that the first battery 200 and the second battery 300 can be charged normally in parallel at 400V.

[0161] It should be noted that the open-circuit diagnosis of the first switch 10 / third switch 30 is performed before high voltage is applied (main circuit switch 82 is open). If the first switch 10 and the third switch 30 are closed when the second switch 20 and the main circuit switch 82 are open, and only one switch is open, the open-circuit fault cannot be diagnosed. This is because even if one of the first switch 10 or the third switch 30 is stuck together, the first sampling point S1 can still sample the voltage of the first battery 200 or the second battery 300, which cannot meet the judgment condition. In this case, the open-circuit diagnosis of the first switch 10 or the third switch 30 can be distinguished after high voltage is applied.

[0162] It should also be noted that the main circuit switch 82 being open indicates before high voltage is applied, and the main circuit switch 82 being closed indicates after high voltage is applied.

[0163] In some embodiments, see [link to relevant documentation]. Figure 4 The battery management system 100 may also include a main circuit switch 82, and the processor 70 may be used for: If the first switch 10 and the main circuit switch 82 are closed and the second switch 20 is open, then the first switch 10 is determined to have an open circuit fault if at least one of the following two relationships is satisfied.

[0164] U1≤b1*U2; |Shunt2|≤I1 and |Shunt1|≥I2; U1 represents the first sampling voltage, U2 represents the second sampling voltage, Shunt1 represents the main circuit current, Shunt2 represents the branch current, b1 is a preset value less than 0.5, I1 and I2 are preset values, and I1 < I2.

[0165] The preset values ​​b1, I1, and I2 are used to set the judgment thresholds to distinguish between normal and fault conditions. By adjusting the magnitude of these preset values, the sensitivity and accuracy of fault diagnosis can be adjusted. These values ​​can be set according to actual needs, and this application embodiment does not limit this.

[0166] For example, I1 is a small current, such as 5A, and I2 is a large current, such as 100A.

[0167] Specifically, when the first switch 10 and the main circuit switch 82 are closed, and the second switch 20 is open, theoretically, the first sampling point and the first battery 200 can form an electrical connection with the main circuit through the first switch 10. In this case, the voltage U1 of the first sampling point S1 should be close to the positive terminal voltage of the first battery 200, that is, close to the voltage U2 of the second sampling point S2. If the first switch 10 has an open circuit fault, although the control signal indicates that it is closed, in reality, no effective electrical connection is formed between the first battery 200 and the first sampling point S1. Therefore, it can be determined that the first switch 10 has an open circuit fault when U1≤b1*U2.

[0168] Furthermore, under normal circumstances, when the first switch 10 is closed, the branch current Shunt2 should reflect the current in the branch where the first battery 200 is located, while the main circuit current Shunt1 reflects the current in the entire main circuit. Therefore, by comparing the relationship between the branch current Shunt2 and the preset value I1, and the main circuit current Shunt1 and the preset value I2, it can be determined whether the first switch 10 has an open circuit fault. When |Shunt2|≤I1 and |Shunt1|≥I2, it can be considered that the current in the branch where the first battery 200 is located is abnormally small while the current in the main circuit is relatively large, thus inferring that the first switch 10 may have an open circuit fault.

[0169] This application embodiment makes a comprehensive judgment by combining voltage and current sampling data, which can more accurately diagnose whether the first switch 10 has an open circuit fault. The redundant fault diagnosis mechanism improves the reliability of the system and can ensure that the first switch 10 has an open circuit fault and can be detected and dealt with in a timely manner.

[0170] In some embodiments, see [link to relevant documentation]. Figure 4 The battery management system 100 may also include a main circuit switch 82, and the processor 70 may be used for: If the third switch 30 and the main circuit switch 82 are closed and the second switch 20 is open, then the third switch 30 is determined to have an open circuit fault if at least one of the following two relationships is satisfied.

[0171] U1≤b2*U2; |Shunt1-Shunt2|≤b2*Shunt1 and |Shunt1|≥I2; U1 represents the first sampling voltage, Shunt1 represents the main circuit current, Shunt2 represents the branch current, b2 is a preset value less than 0.5 (e.g., 5%), and I2 is a preset value.

[0172] Specifically, when the third switch 30 and the main circuit switch 82 are closed and the second switch 20 is open, theoretically, the first sampling point S1 and the second battery 300 can form an electrical connection through the third switch 30. In this case, the voltage U1 of the first sampling point S1 should be close to the positive terminal voltage of the second battery 300. If the third switch 30 has an open circuit fault, although the control signal indicates that it is closed, in reality, no effective electrical connection is formed between the second battery 300 and the first sampling point S1. Therefore, if U1 ≤ b1 * U2, it can be determined that the third switch 30 has an open circuit fault.

[0173] In addition, the difference between the main circuit current Shunt1 and the branch current Shunt2 where the first battery 200 is located can be compared with the relationship between the main circuit current Shunt1 and the preset value I2 to determine whether the third switch 30 has an open circuit fault.

[0174] This application embodiment uses a combination of voltage and current sampling data for comprehensive judgment, which can more accurately diagnose whether the third switch 30 has an open circuit fault. Furthermore, the redundant fault diagnosis mechanism improves the reliability of the system and ensures that an open circuit fault in the third switch 30 can be detected and dealt with in a timely manner.

[0175] It should be noted that by adding current as a supplementary judgment condition, the judgment of the first switch 10 and the third switch 30 does not need to distinguish their respective states.

[0176] In some embodiments, the processor 70 may be used for: If U1≤b3*U2, and the first switch 10 and the third switch 30 are open while the second switch 20 is closed, then the second switch 20 is determined to have an open circuit fault.

[0177] U1 represents the first sampling voltage, U2 represents the second sampling voltage, and b3 is a preset value less than 0.5.

[0178] Where b3 is a preset value less than 0.5, such as 0.4.

[0179] Specifically, when the first switch 10 and the third switch 30 are open and the second switch 20 is closed, theoretically the first sampling point S1, the second battery 300 and the first battery 200 can be electrically connected through the second switch 20. Therefore, if U1≤b3*U2, it can be determined that the second switch 20 has an open circuit fault.

[0180] The embodiments of this application can promptly diagnose open-circuit faults in the second switch 20, thereby ensuring that the first battery 200 and the second battery 300 can be normally charged / discharged in series at 800V.

[0181] It should be noted that the embodiments of this application provide a redundant relay diagnostic scheme. By arranging three high-voltage sampling points (first sampling point S1, second sampling point S2, and third sampling point S3), the sticking / open circuit diagnosis of three switches is performed. At the same time, the multiple sampling points are mutually checked and verified by accumulating the cell voltages of the two batteries. Meanwhile, the coupling current sampling value improves the accuracy of switch sticking and open circuit diagnosis, ensuring that switch sticking is not missed, thus preventing accidental switch closure that could lead to battery pack short circuit and serious consequences.

[0182] The above describes the specific process by which the battery management system 100 provided in this application determines switch sticking faults (sticking faults can be simply understood as faults where the switch should be open but is not) and open circuit faults (open circuit faults can be simply understood as faults where the switch should be closed but is not). Switch sticking poses a safety risk; therefore, sticking diagnosis combines high-voltage sampling and cell voltage accumulation for judgment to improve the accuracy of the strategy. Open circuit diagnosis has a lower safety risk; therefore, high-voltage sampling is used for judgment. Only when high-voltage sampling is ineffective is cell voltage accumulation used as a substitute, improving the robustness of the strategy.

[0183] The charging strategy of the battery management system 100 provided in the embodiments of this application is described below.

[0184] In some embodiments, the processor 70 may also be used for: When the output voltage of the charging device 400, which is electrically connected to the battery management system 100, is greater than the threshold voltage, the second switch 20 is closed, while the first switch 10 and the third switch 30 are in the open state.

[0185] The charging device 400 can be used to charge the battery.

[0186] Specifically, when the output voltage of the charging device 400 is greater than the threshold voltage, it indicates that the charging device 400 is an 800V charging device. At this time, the second switch 20 can be closed while the first switch 10 and the third switch 30 are open, so that the first battery 200 and the second battery 300 are connected in series, thereby realizing the series 800V charging mode.

[0187] In this embodiment, when the output voltage of the charging device 400 is greater than the threshold voltage, a series charging mode of the first battery 200 and the second battery 300 is adopted. The battery pack (the first battery 200 and the second battery 300) can make full use of the high output voltage (such as 800V high voltage) of the charging device 400, reduce charging time, and improve charging efficiency.

[0188] It should be noted that the system only switches to parallel charging of the two batteries when testing a 400V charging station; otherwise, it operates in series at 800V. Due to differences in battery consistency and internal resistance, a voltage difference exists between the two batteries during actual use. If the voltage difference is significant and the 400V charging device is detected, the switch (such as a relay) is immediately closed, it can easily cause the relay to stick and fail. Therefore, it is necessary to control when the relay switches to 400V charging.

[0189] In some embodiments, the processor 70 may also be used for: When the output voltage of the charging device 400 electrically connected to the battery management system 100 is less than the threshold voltage, if |VM1-VM2|≤V1, the first switch 10 and the third switch 30 are closed, and the second switch 20 is in the open state; VM1 represents the first battery voltage, VM2 represents the second battery voltage, and V1 is a preset value.

[0190] Before deciding to enter the parallel charging mode, it is determined whether the difference between the first battery voltage VM1 and the second battery voltage VM2 is small enough to ensure that the voltage difference between the two batteries will not be too large during parallel charging, thereby avoiding current imbalance and potential battery damage.

[0191] Specifically, the processor 70 can monitor the output voltage of the charging device 400. If it is lower than a preset threshold voltage, the processor 70 determines that the charging device 400 cannot support the series charging mode. When the processor 70 detects that the output voltage of the charging device 400 is lower than the preset threshold voltage, it will further determine the difference between the first battery voltage VM1 and the second battery voltage VM2. If the difference satisfies |VM1-VM2|≤V1 (V1 is a preset value, such as 5V), the processor 70 will control the first switch 10 and the third switch 30 to close, and simultaneously control the second switch 20 to open, thereby entering the parallel charging mode.

[0192] This application embodiment describes a charging strategy of the battery management system 100 when the output voltage of the charging device 400 is less than a threshold voltage. For example, if the output voltage of the charging device 400 is 400V, a parallel charging mode can be adopted. Before entering the parallel charging mode, it can also be determined whether the difference between the first battery voltage VM1 and the second battery voltage VM2 is small enough, so as to ensure that the voltage difference between the two batteries is not too large during parallel charging, thereby avoiding current imbalance and potential battery damage, and ensuring the safety and reliability of the charging process.

[0193] In some embodiments, the processor 70 may also be used for: If the output voltage of the charging device 400 electrically connected to the battery management system 100 is less than the threshold voltage, and if VM1-VM2>V1, the third switch 30 is first closed, while the first switch 10 and the second switch 20 are in the open state. The charging current Ia is requested until the voltage of the second battery 300 is charged to a level where the voltage difference between it and the first battery 200 is less than V2. The first switch 10 is then closed after the charging current drops below Ia.

[0194] VM1 represents the first battery voltage, VM2 represents the second battery voltage, V1 and V2 are preset values, and V2 < V1, Ia is the current safety threshold.

[0195] When a new energy vehicle plugs in the charging gun, the battery management system 100 can interact with the charging device to obtain relevant information about the charging device and determine the output voltage of the charging device.

[0196] Specifically, when the processor 70 detects that the output voltage of the charging device 400 is lower than a preset threshold voltage, it will further determine the difference between the first battery voltage VM1 and the second battery voltage VM2. If the difference satisfies |VM1-VM2|>V1 (V1 is a preset value, such as 5V), it indicates that the two battery voltages are unbalanced. The following charging strategy needs to be adopted to avoid directly closing the switch when the branch voltage difference is too large, thus preventing the switch from sticking together: 1) Charge batteries with lower voltage individually (by judging the voltage difference between VM1 and VM2, it can be determined which branch needs to be charged first, such as the second battery 300).

[0197] Switch control: The processor 70 controls the third switch 30 to close, while ensuring that the first switch 10 and the second switch 20 are open, so that the second battery 300 is connected to the charging device 400 alone and starts charging.

[0198] Charging target: Gradually increase the voltage of the second battery 300 by charging it separately until the voltage difference between it and the first battery 200 is less than V2 (V2 is a preset voltage difference threshold. V2 needs to have a certain hysteresis range with V1 to avoid jumping back and forth at the zero point, causing the relay to repeatedly open and close, such as 3V).

[0199] 2) Request the charging current Ia and monitor it.

[0200] Request charging current: When the voltage of the second battery 300 is close to the voltage of the first battery 200 (the voltage difference is less than V2), the processor 70 requests the charging device 400 to provide a charging current Ia (Ia is the current safety threshold, under which there is no risk of the relay closing under load, such as 5A).

[0201] Current monitoring: During charging, the processor 70 monitors the charging current in real time to ensure it does not exceed Ia. This is to prevent the battery from overheating or being damaged due to excessive current.

[0202] 3) Close the first switch 10 to achieve parallel charging.

[0203] When the charging current drops below Ia, the processor 70 controls the first switch 10 to close while keeping the second switch 20 open (ensuring no series path is formed). At this time, the first battery 200 and the second battery 300 are connected in parallel for parallel charging, and eventually the first battery 200 and the second battery 300 are charged in parallel until fully charged.

[0204] This application embodiment describes a charging strategy for the battery management system 100 when the output voltage of the charging device 400 is less than a threshold voltage, and the voltage difference between the first battery 200 and the second battery 300 is large (VM1-VM2>V1). By first charging the battery with the lower voltage (such as the second battery 300) individually, and then gradually charging them in parallel, the risk of excessive current or battery damage caused by battery voltage imbalance is avoided. This ensures that the battery pack is charged safely and efficiently under voltage imbalance conditions, and ultimately achieves voltage balance. Furthermore, a current safety threshold Ia is set during the charging process to avoid the impact of large current on the battery, ensuring the safety and reliability of the charging process and extending the battery's lifespan.

[0205] In some embodiments, the processor 70 may also be used for: When the output voltage of the charging device 400 electrically connected to the battery management system 100 is less than the threshold voltage, if VM2-VM1>V1, the first switch 10 is first closed, and the third switch 30 and the second switch 20 are in the open state. The charging current Ia is requested until the voltage of the first battery 200 is charged to a level where the voltage difference with the second battery 300 is less than V2. The third switch 30 is then closed after the charging current drops below Ia.

[0206] VM1 represents the first battery voltage, VM2 represents the second battery voltage, V1 and V2 are preset values, and V2 < V1, Ia is the current safety threshold.

[0207] Specifically, when the processor 70 detects that the output voltage of the charging device 400 is lower than a preset threshold voltage, it will further determine the difference between the voltage of the first battery VM1 and the voltage of the second battery VM2. If the difference satisfies |VM1-VM2|>V1 (V1 is a preset value), it indicates that the voltages of the two batteries are unbalanced, and a special charging strategy needs to be adopted: charge the battery with the lower voltage separately (such as the first battery 200); close the third switch 30 to achieve parallel charging.

[0208] This application embodiment describes a charging strategy for the battery management system 100 when the output voltage of the charging device 400 is less than a threshold voltage, and the voltage difference between the first battery 200 and the second battery 300 is large (VM1-VM2>V1). By first charging the battery with the lower voltage (such as the first battery 200) individually, and then gradually charging them in parallel, the risk of excessive current or battery damage caused by battery voltage imbalance is avoided. This ensures that the battery pack is charged safely and efficiently under voltage imbalance conditions, and ultimately achieves voltage balance. Furthermore, a current safety threshold Ia is set during the charging process to avoid the impact of large current on the battery, ensuring the safety and reliability of the charging process and extending the battery's lifespan.

[0209] Figure 5 This is another structural schematic diagram of the battery management system 100 provided in the embodiments of this application.

[0210] In some embodiments, such as Figure 5 As shown, the battery management system 100 may also include a first fuse 83.

[0211] The first fuse 83 and the first switch 10 are connected in series between the first sampling point S1 and the second sampling point S2.

[0212] In this embodiment of the application, the newly added first fuse 83 and the first switch 10 are connected in series between the first sampling point S1 and the second sampling point S2. When the current flowing through the first fuse 83 exceeds its rated value, the fuse wire inside the first fuse 83 will melt due to overheating, thereby cutting off the circuit and preventing equipment damage caused by excessive current.

[0213] In some embodiments, see [link to relevant documentation]. Figure 4 The battery management system 100 may also include a second fuse 84.

[0214] The second fuse 84 and the third switch 30 are connected in series between the negative terminal of the second battery 300 and the reference point G.

[0215] In this embodiment, the newly added second fuse 84 and third switch 30 are connected in series between the negative terminal of the second battery 300 and the reference point G. When the current flowing through the second fuse 84 exceeds its rated value, the fuse wire inside the second fuse 84 will melt due to overheating, thereby cutting off the circuit and preventing equipment damage caused by excessive current. For example, if the branch of the first battery 200 is short-circuited, it can be protected by the passive fuse (first fuse 83); if the branch of the second battery 300 is short-circuited, it will be protected by the passive fuse (second fuse 84), avoiding serious consequences caused by battery short circuits.

[0216] In one example, the first switch 10, the second switch 20, and the third switch 30 are all relays. The three relays control the series and parallel use of two 400V battery packs. The main circuit uses an active fuse 81 for short circuit protection, and the two branch circuits use passive fuses (such as the first fuse 83 and the second fuse 84) for short circuit protection to meet the functional safety protection design.

[0217] Figure 6 This is a schematic diagram of the charging process of a battery management system according to a scenario embodiment of this application.

[0218] In a scenario example, such as Figure 6 As shown, the charging process of the battery management system 100 may include steps S110 to S168.

[0219] S110, gun inserted.

[0220] After the new energy vehicle plugs in the charging gun, the battery management system 100 can interact with the charging device 400 to obtain relevant information about the charging device 400 and determine the output voltage of the charging device 400.

[0221] Steps S121 to S123 describe the charging process when the charging device 400 is an 800V charging device.

[0222] S121, Based on the output voltage of the charging device 400, it is determined that the charging device 400 is an 800V charging device.

[0223] S122, when the charging device 400 is an 800V charging device, close the second switch 20.

[0224] S123, the first battery 200 and the second battery 300 are connected in series for charging.

[0225] Steps S130 to S168 are the charging process when the charging device 400 is a 400V charging device.

[0226] Steps S141 to S143 are the charging process when the voltage difference between the first battery 200 and the second battery 300 is not large.

[0227] S130, Based on the output voltage of the charging device 400, it is determined that the charging device 400 is a 400V charging device.

[0228] S141, if the charging device 400 is a 400V charging device, determine whether |VM1-VM2|≤V1 is satisfied.

[0229] S142, if |VM1-VM2|≤V1 (V1 is a preset value, such as 5V), it means that the voltage difference between the first battery 200 and the second battery 300 is not large. At this time, the first switch 10 and the third switch 30 can be closed.

[0230] S143, the first battery 200 and the second battery 300 are connected in parallel for charging.

[0231] Steps S151 to S158 are the charging process when the voltage difference between the first battery 200 and the second battery 300 is large and the voltage of the second battery 300 is low.

[0232] S151, if |VM1-VM2|≤V1 is not satisfied, further determine whether VM1-VM2>V1 is satisfied.

[0233] S152, when VM1-VM2>V1, it indicates that the voltage difference between the first battery 200 and the second battery 300 is large and the voltage of the second battery 300 is low. At this time, the third switch 30 can be closed.

[0234] S153, the second battery 300 is charged separately.

[0235] S154, determine whether VM1-VM2≤V2 (V2 is a preset voltage difference threshold, V2 needs to have a certain hysteresis range with V1 to avoid jumping back and forth at the zero point, causing the relay to repeatedly open and close, such as 3V).

[0236] S155 If VM1-VM2≤V2 is satisfied, it means that the voltage difference between the first battery 200 and the second battery 300 has become smaller. At this time, a charging current Ia can be requested from the charging device 400 (Ia is the current safety threshold. There is no risk of the relay closing under load at this current, such as 5A).

[0237] S156, determine whether the loop current ≤ Ia is satisfied.

[0238] S157, under the condition that the loop current ≤ Ia, close the first switch 10.

[0239] S158, the first battery 200 and the second battery 300 are connected in parallel for charging.

[0240] Steps S161 to S168 are the charging process when the voltage difference between the first battery 200 and the second battery 300 is large and the voltage of the first battery 200 is low.

[0241] S161, if |VM1-VM2|≤V1 is not satisfied, determine whether VM2-VM1>V1 is satisfied.

[0242] S162, if VM2-VM1>V1 is satisfied, then the first switch 10 is closed.

[0243] S163, first battery 200, charged separately.

[0244] S164, determine whether VM2-VM1≤V2 is satisfied.

[0245] S165, if VM2-VM1≤V2 is satisfied, then a charging current Ia can be requested from the charging device 400.

[0246] S166, determine whether the loop current ≤ Ia is satisfied.

[0247] S167, under the condition that the loop current ≤ Ia, close the third switch 30.

[0248] S168, the first battery 200 and the second battery 300 are connected in parallel for charging.

[0249] This application embodiment can intelligently select the most suitable charging mode based on the output voltage of the charging device 400 and the voltage difference between the first battery 200 and the second battery 300. This includes 800V series charging, 400V parallel charging, and a method that first charges the battery with the lower voltage individually and then gradually charges it in parallel at 400V when the voltage difference between the batteries is large. This ensures the efficiency of the charging process, the safety and reliability of the charging process, and extends the service life of the batteries.

[0250] It should be noted that the embodiments of this application are mainly for fault diagnosis of three switches used for 400V / 800V switching. The main positive, main negative, pre-charge, charge positive, and charge negative relays in conventional high-voltage topologies can use conventional diagnostic schemes, and the sampling of high voltage and current can also use conventional sampling schemes, which can be implemented by the processor 70 of the embodiments of this application.

[0251] Based on the same inventive concept, embodiments of this application also provide a battery pack. For example... Figure 7As shown, the battery pack 1000 includes a first battery 200, a second battery 300, and a battery management system 100 as described in any of the above embodiments. It is understood that the battery pack 1000 has the beneficial effects of the battery management system 100 provided in the embodiments of this application. For details, please refer to the specific descriptions of the battery management system 100 in the above embodiments; these descriptions will not be repeated here.

[0252] Based on the same inventive concept, this application also provides an electrical device. For example... Figure 8 As shown, the power-consuming device 2000 includes a battery pack 1000. The battery pack 1000 includes the battery management system 100 in any of the above embodiments. It is understood that the power-consuming device 2000 has the beneficial effects of the battery management system 100 provided in the embodiments of this application. For details, please refer to the specific descriptions of the battery management system 100 in the above embodiments, which will not be repeated here.

[0253] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0254] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery management system, characterized in that, It includes a first switch, a second switch, a third switch, a voltage sampling module, a first current sampling module, a second current sampling module, and a processor; The first switch is electrically connected between the first sampling point and the second sampling point; The second switch is connected in series between the first battery and the second battery, wherein the second switch and the second battery are connected in parallel with the first switch between the first sampling point and the second sampling point; The third switch is connected in parallel with the first battery and the second switch; The voltage sampling module is electrically connected to the first sampling point, the second sampling point, the first battery, and the second battery, and is used to collect the first sampling voltage of the first sampling point, the second sampling voltage of the second sampling point, the first battery voltage of the first battery, and the second battery voltage of the second battery. The first current sampling module is connected to the main circuit of the first battery and the second battery, and is used to collect the main circuit current. The second current sampling module is connected to the branch where the first battery is located and is used to collect the branch current; The processor, connected to the voltage sampling module, the first current sampling module, and the second current sampling module, is used to compare the first sampled voltage, the second sampled voltage, the first battery voltage, and the second battery voltage, and, in conjunction with the changes in the main circuit current and the branch current, determine whether the first switch, the second switch, and the third switch have sticking or open circuit faults.

2. The battery management system according to claim 1, characterized in that, The battery management system also includes an active fuse, which is electrically connected between the first sampling point and the third sampling point; The voltage sampling module is also electrically connected to the third sampling point, and is used to collect the third sampling voltage of the third sampling point; The processor is further configured to: determine that the voltage sampling module has a sampling fault when the deviation between the first sampling voltage and the third sampling voltage is greater than a first preset deviation.

3. The battery management system according to claim 2, characterized in that, The processor is further configured to: when the voltage sampling module cannot acquire the first sampling voltage but can acquire the third sampling voltage, use the third sampling voltage to replace the first sampling voltage for diagnosing switch faults.

4. The battery management system according to any one of claims 1-3, characterized in that, The processor is also used for: If the voltage sampling module cannot acquire the second sampling voltage but can acquire the first battery voltage, the first battery voltage is used to replace the second sampling voltage for diagnosing the switch fault.

5. The battery management system according to claim 1, characterized in that, The processor is used for: When the first switch, the second switch, and the third switch are all open, the voltage collected by the voltage sampling module is used to determine whether there is a sticking fault in the first switch, the second switch, and the third switch.

6. The battery management system according to claim 5, characterized in that, The processor is used for: If the first sampling voltage is greater than the first threshold when the first switch, the second switch, and the third switch are all open, it is determined that at least one of the first switch, the second switch, and the third switch has an adhesion fault.

7. The battery management system according to claim 5, characterized in that, The processor is used for: If the first switch, the second switch, and the third switch are all open, and at least one of the following three relationships is satisfied, then it is determined that the first switch or the third switch has an adhesion fault. |U1-U2|≤a1*U2; |U1-VM1|≤a1*VM1; |U1-VM2|≤a1*VM2; U1 represents the first sampling voltage, U2 represents the second sampling voltage, VM1 represents the first battery voltage, VM2 represents the second battery voltage, and a1 is a preset value less than 0.

5.

8. The battery management system according to claim 7, characterized in that, The processor is also used for: If |U1-VM1| < |U1-VM2|, then the first switch is determined to have an adhesion fault.

9. The battery management system according to claim 7, characterized in that, The processor is also used for: If |U1-VM1|>|U1-VM2|, then the third switch is determined to have an adhesion fault.

10. The battery management system according to claim 1, characterized in that, The processor is used for: If the first switch, the second switch, and the third switch are all open, and at least one of the following two relationships is satisfied, then the second switch is determined to have an adhesion fault. |U1-2*U2|≤a2*2*U2; |U1-(VM1+VM2)|≤a2*(VM1+VM2); U1 represents the first sampling voltage, U2 represents the second sampling voltage, VM1 represents the first battery voltage, VM2 represents the second battery voltage, and a2 is a preset value less than 0.

5.

11. The battery management system according to claim 1, characterized in that, The battery management system also includes a main circuit switch, and the processor is used for: When the main circuit switch is open, the voltage collected by the voltage sampling module is used to determine whether there is an open circuit fault in the first switch and the third switch.

12. The battery management system according to claim 11, characterized in that, The processor is used for: If U1≤b1*U2, and the first switch is closed while the second switch, the third switch, and the main circuit switch are open, then the first switch is determined to have an open circuit fault. U1 represents the first sampling voltage, U2 represents the second sampling voltage, and b1 is a preset value less than 0.

5.

13. The battery management system according to claim 11, characterized in that, The processor is used for: If the third switch is closed and the first switch, the second switch, and the main circuit switch are open, and U1 ≤ b1 * U2, then the third switch is determined to have an open circuit fault. U1 represents the first sampling voltage, U2 represents the second sampling voltage, and b1 is a preset value less than 0.

5.

14. The battery management system according to claim 11, characterized in that, The battery management system also includes a main circuit switch, and the processor is used for: If U1≤b1*U2, and the first switch and the third switch are closed while the second switch and the main circuit switch are open, then it is determined that the first switch and the third switch have an open circuit fault. U1 represents the first sampling voltage, U2 represents the second sampling voltage, and b1 is a preset value less than 0.

5.

15. The battery management system according to claim 1, characterized in that, The battery management system also includes a main circuit switch, and the processor is used for: When the main circuit switch is closed, based on the voltage collected by the voltage sampling module and the current collected by the first current sampling module and the second current sampling module, it is determined whether there is an open circuit fault in the first switch and the third switch.

16. The battery management system according to claim 15, characterized in that, The processor is used for: If the first switch and the main circuit switch are closed and the second switch is open, then the first switch is determined to have an open circuit fault if at least one of the following two relationships is satisfied. U1≤b1*U2; |Shunt2|≤I1 and |Shunt1|≥I2; U1 represents the first sampling voltage, U2 represents the second sampling voltage, Shunt1 represents the main circuit current, Shunt2 represents the branch current, b1 is a preset value less than 0.5, I1 and I2 are preset values, and I1 < I2.

17. The battery management system according to claim 15, characterized in that, The processor is used for: If the third switch and the main circuit switch are closed and the second switch is open, then the third switch is determined to have an open circuit fault if at least one of the following two relationships is satisfied. U1≤b2*U2; |Shunt1-Shunt2|≤b2*Shunt1 and |Shunt1|≥I2; U1 represents the first sampling voltage, Shunt1 represents the main circuit current, Shunt2 represents the branch current, b2 is a preset value less than 0.5, and I2 is a preset value.

18. The battery management system according to claim 1, characterized in that, The processor is used for: If U1≤b3*U2, and the first switch and the third switch are open while the second switch is closed, then the second switch is determined to have an open circuit fault. U1 represents the first sampling voltage, U2 represents the second sampling voltage, and b3 is a preset value less than 0.

5.

19. The battery management system according to claim 1, characterized in that, The processor is also used for: When the output voltage of the charging device electrically connected to the battery management system is greater than the threshold voltage, the second switch is controlled to close, while the first switch and the third switch are in the open state.

20. The battery management system according to claim 1, characterized in that, The processor is also used for: If the output voltage of the charging device electrically connected to the battery management system is less than the threshold voltage, and |VM1-VM2|≤V1, the first switch and the third switch are closed, and the second switch is in the open state. VM1 represents the voltage of the first battery, VM2 represents the voltage of the second battery, and V1 is a preset value.

21. The battery management system according to claim 1, characterized in that, The processor is also used for: When the output voltage of the charging device electrically connected to the battery management system is less than the threshold voltage, if VM1-VM2>V1, the third switch is first controlled to close, and the first and second switches are in the open state. The charging current Ia is requested until the voltage difference between the second battery and the first battery is less than V2. The first switch is controlled to close after the charging current drops below Ia. VM1 represents the voltage of the first battery, VM2 represents the voltage of the second battery, V1 and V2 are preset values, and V2 < V1, and Ia is the current safety threshold.

22. The battery management system according to claim 1, characterized in that, The processor is also used for: When the output voltage of the charging device electrically connected to the battery management system is less than the threshold voltage, if VM2-VM1>V1, the first switch is first controlled to close, and the third switch and the second switch are in the open state. The charging current Ia is requested until the voltage of the first battery is charged to a level where the voltage difference with the second battery is less than V2. The third switch is then controlled to close. VM1 represents the voltage of the first battery, VM2 represents the voltage of the second battery, V1 and V2 are preset values, and V2 < V1, and Ia is the current safety threshold.

23. The battery management system according to claim 1, characterized in that, The battery management system also includes: The first fuse is connected in series with the first switch between the first sampling point and the second sampling point; And / or, a second fuse, connected in series with the third switch between the negative terminal of the second battery and the reference point.

24. A battery pack, characterized in that, It includes a first battery, a second battery, and a battery management system as described in any one of claims 1 to 23.

25. An electrical appliance, characterized in that, Includes the battery pack as described in claim 24.

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