Switching fault diagnosis method and device of battery system, battery system and medium

Abstract

The application discloses a kind of switch fault diagnosis method, device, battery system and medium of battery system.It is determined that the switch fault diagnosis method includes: determining the to-be-diagnosed charge-discharge branch in charge-discharge component, and obtaining the branch current in each to-be-diagnosed charge-discharge branch;When at least two branch currents are not equal, for any to-be-diagnosed charge-discharge branch, when the branch current of to-be-diagnosed charge-discharge branch is less than the first preset current, it is determined that there is open circuit fault in the state control switch in to-be-diagnosed charge-discharge branch;Wherein, when battery system is in discharging state, state control switch is discharge switch;When battery system is in charging state, state control switch is charging switch.The application can realize the on-line fault diagnosis of each switch element in battery system.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a method, apparatus, battery system, and medium for diagnosing switching faults in a battery system. Background Technology

[0002] Currently, considering energy consumption and safety issues during battery system operation, switching elements are incorporated into the charging and discharging circuits to control the circuit's on / off state. MOSFETs offer significant advantages over other switching elements in terms of cost, noise, and size, making them increasingly popular for both charging and discharging. Furthermore, to increase the charging and discharging current capacity of the circuit, current technologies typically employ multiple parallel charging and discharging branches, each consisting of a charging switch and a discharging switch. However, faults in the switching elements themselves can affect the battery system's charging and discharging process. For example, an open-circuit fault in a switching element may prevent the corresponding charging / discharging branch from carrying current, causing other branches to exceed their rated current, thus compromising the safety and reliability of the charging and discharging process.

[0003] However, in the existing technology, there are few diagnostic strategies for multi-parallel MOSFET switching schemes in battery systems, especially lacking online diagnostic schemes for switching elements. This makes it impossible to diagnose open-circuit faults of switching elements in a timely manner, affecting the safety and reliability of the battery system. Summary of the Invention

[0004] This invention provides a method, apparatus, battery system, and medium for diagnosing switching faults in a battery system, enabling online fault diagnosis of switching components in the battery system.

[0005] In a first aspect, embodiments of the present invention provide a method for diagnosing switch faults in a battery system. The battery system includes a battery assembly and a charging / discharging assembly connected between the battery assembly and an external device. The charging / discharging assembly includes multiple parallel charging / discharging branches, and each charging / discharging branch includes a charging switch and a discharging switch connected in series.

[0006] The battery system switching fault diagnosis method includes:

[0007] Identify the charge / discharge branch to be diagnosed in the charge / discharge assembly, and obtain the branch current in each of the charge / discharge branches to be diagnosed;

[0008] When at least two of the branch currents are not equal, for any charge / discharge branch to be diagnosed, if the branch current of the charge / discharge branch to be diagnosed is less than the first preset current, it is determined that the state control switch in the charge / discharge branch to be diagnosed has an open circuit fault.

[0009] Wherein, when the battery system is in a discharging state, the state control switch is the discharge switch; when the battery system is in a charging state, the state control switch is the charging switch.

[0010] Optionally, when at least two of the branch currents are not equal, the method further includes:

[0011] For any charge / discharge branch to be diagnosed, if the branch current of the charge / discharge branch to be diagnosed is greater than the second preset current, and there are other charge / discharge branches to be diagnosed whose branch current exceeds a preset multiple of the branch current of the charge / discharge branch to be diagnosed, it is determined that the non-state control switch in the charge / discharge branch to be diagnosed has an open circuit fault.

[0012] Wherein, the second preset current is greater than or equal to the first preset current; when the battery system is in the discharge state, the non-state control switch is the charging switch; when the battery system is in the charging state, the non-state control switch is the discharging switch.

[0013] Optionally, before obtaining the branch current in each of the charge / discharge branches to be diagnosed, the method further includes:

[0014] Obtain the main circuit current; wherein, the main circuit current is the current between the battery assembly and the external device;

[0015] Determine whether the current in the main circuit is 0;

[0016] If so, when the difference between the positive voltage of the battery assembly and the positive voltage of the external device is greater than a preset voltage difference, it is determined that the status control switch in all the charging and discharging branches to be diagnosed has an open circuit fault.

[0017] If not, then perform the step of obtaining the branch current in each of the charging and discharging branches to be diagnosed.

[0018] Optionally, the charge / discharge state of the battery system is determined based on the main circuit current and / or the current direction of the branch circuit;

[0019] When the main circuit current and / or the branch circuit current flows from the battery assembly to the external device, the battery system is in a discharging state;

[0020] The battery system is in a charging state when the main circuit current and / or the branch circuit current flows from the external device to the battery assembly.

[0021] Optionally, the preset multiple is greater than or equal to three times.

[0022] Optionally, the first preset current is less than or equal to 1A.

[0023] Optionally, determining the charge / discharge branch to be diagnosed in the charge / discharge assembly includes:

[0024] The charging / discharging branch in which both the charging switch and the discharging switch receive a conduction signal is taken as the charging / discharging branch to be diagnosed.

[0025] Optionally, the charging and discharging branch further includes a shunt connected in series with the charging switch and the discharging switch;

[0026] Obtaining the branch current in the charge / discharge branch to be diagnosed includes:

[0027] The branch current in the charge / discharge branch to be diagnosed is determined based on the voltage across the shunt and the resistance of the shunt.

[0028] Secondly, embodiments of the present invention also provide a battery system switch fault diagnosis device, comprising:

[0029] The current acquisition module is used to identify the charge / discharge branch to be diagnosed in the charge / discharge assembly and acquire the branch current in each of the charge / discharge branches to be diagnosed.

[0030] The first determination module is used to determine that the state control switch in the charging and discharging branch to be diagnosed has an open circuit fault when the branch current of the charging and discharging branch to be diagnosed is less than the first preset current, when at least two of the branch currents are not equal.

[0031] Wherein, when the battery system is in a discharging state, the state control switch is the discharge switch; when the battery system is in a charging state, the state control switch is the charging switch.

[0032] Thirdly, embodiments of the present invention also provide a battery system, including: a battery component, a controller, and a charging and discharging component connected between the battery component and an external device; the charging and discharging component includes multiple parallel-connected charging and discharging branches, and each charging and discharging branch includes a charging switch and a discharging switch connected in series.

[0033] The controller is electrically connected to the control terminal of each of the charging switches and the control terminal of each of the discharging switches, respectively.

[0034] The controller includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to execute the battery system switching fault diagnosis method provided in any embodiment of the present invention.

[0035] Fourthly, embodiments of the present invention also provide a computer-readable storage medium storing computer instructions, which are used to cause a processor to execute and implement the battery system switching fault diagnosis method provided in any embodiment of the present invention.

[0036] The battery system switch fault diagnosis method provided in this invention obtains the branch current of each charge / discharge branch to be diagnosed in the battery system, and determines whether the state control switch in each charge / discharge branch to be diagnosed has an open circuit fault based on the magnitude of the branch current. When the branch current is less than a first preset current, it indicates that the branch current is close to zero, and the charge / discharge branch to be diagnosed is close to an open circuit. Therefore, it can be determined that the state control switch in the charge / discharge branch to be diagnosed has an open circuit fault. Since the corresponding state control switches are different in the charging state and the discharging state, by combining the diagnosis results in the charging state and the discharging state, this invention can effectively diagnose open circuit faults of each switching element in a multi-parallel structure. Furthermore, this invention directly diagnoses switch faults based on current data, without sending other control signals to each switching element during the test, without testing in a specific scenario, and without changing the operating state of the battery system. Therefore, it can achieve real-time online fault diagnosis of each switching element. In addition, the first preset current involved in this invention can be calibrated according to the actual circuit configuration and application scenario, making this invention highly compatible and widely applicable.

[0037] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the structure of a battery system provided in an embodiment of the present invention;

[0040] Figure 2 This is a schematic flowchart of a battery system switch fault diagnosis method provided in an embodiment of the present invention;

[0041] Figure 3 This is a flowchart illustrating another method for diagnosing switch faults in a battery system provided in an embodiment of the present invention.

[0042] Figure 4 This is a flowchart illustrating another method for diagnosing switch faults in a battery system provided in an embodiment of the present invention.

[0043] Figure 5 This is a schematic diagram of another battery system provided in an embodiment of the present invention;

[0044] Figure 6 This is a flowchart illustrating another method for diagnosing switch faults in a battery system provided in an embodiment of the present invention.

[0045] Figure 7 This is a schematic diagram of the structure of a battery system switch fault diagnosis device provided in an embodiment of the present invention;

[0046] Figure 8 This is a schematic diagram of the structure of a controller provided in an embodiment of the present invention. Detailed Implementation

[0047] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0048] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0049] This invention provides a method for diagnosing switch faults in a battery system. This method is applicable to online diagnosis of open-circuit faults in the charging and discharging switches of a battery system with a multi-switch parallel structure. The method can be executed by a switch fault diagnosis device for the battery system, which can be implemented in hardware and / or software and can be configured in the controller of the battery system. To better explain this method, the following first combines... Figure 1 A brief description of the battery system structure is provided.

[0050] Figure 1This is a schematic diagram of a battery system provided in an embodiment of the present invention. See also... Figure 1 The battery system includes a battery assembly 10 and a charging / discharging assembly 20 connected between the battery assembly 10 and an external device 30. The external device 30 can be a charging device that charges the battery assembly 10 via the charging / discharging assembly 20; or, the external device 30 can be an external load that supplies power to the external load via the charging / discharging assembly 20. For example, the positive terminal of the battery assembly 10 is connected to the positive terminal of the external device 30 via the charging / discharging assembly 20 (e.g., the first connection terminal N1 of the charging / discharging assembly 20 is connected to the positive terminal of the battery assembly 10, and the second connection terminal N2 of the charging / discharging assembly 20 is connected to the positive terminal of the external device 30), and the negative terminal of the battery assembly 10 is directly connected to the negative terminal of the external device 30, forming a complete charging / discharging circuit for the battery system; or, the charging / discharging assembly 20 can also be connected between the negative terminal of the battery assembly 10 and the negative terminal of the external device 30.

[0051] Specifically, the charging / discharging assembly 20 includes multiple charging / discharging branches 21 connected in parallel between the first connection terminal N1 and the second connection terminal N2 to improve the current flow capability of the charging / discharging assembly 20. Each charging / discharging branch 21 may include a charging switch DCB and a discharging switch CCB connected in series between the first connection terminal N1 and the second connection terminal N2. The charging switch DCB and the discharging switch CCB may employ switching elements with the same structure, such as MOSFETs with body diodes.

[0052] Additionally, the battery system may include a controller 40, which is connected to the first connection terminal N1, the second connection terminal N2, and the control terminals of each switching element. The controller 40 can be used to execute the switch fault diagnosis method provided in this embodiment of the invention. Furthermore, the controller 40 can also be used to control the charging and discharging state of the battery assembly 10 and the on / off state of each switching element. To facilitate the acquisition of current in each charging and discharging branch 21, a shunt connected in series with the charging switch CCB and the discharging switch DCB can be provided in each charging and discharging branch 21, and a voltage sampling module AFE can be connected to each shunt and the controller 40. The voltage sampling module AFE can acquire the analog voltage across the shunt, and the controller 40 can determine the branch current in the charging and discharging branch 21 based on the analog voltage and the resistance of the corresponding shunt.

[0053] Based on the structure of the battery system described above, this embodiment of the invention provides a method for online diagnosis of open-circuit faults of each switching element in each target conducting branch when at least two charging and discharging branches 21 are target conducting branches. Figure 2 This is a schematic flowchart of a battery system switch fault diagnosis method provided in an embodiment of the present invention. See also... Figure 2 The switch fault diagnosis method includes:

[0054] S11. Determine the charge / discharge branch to be diagnosed in the charge / discharge assembly, and obtain the branch current in each charge / discharge branch to be diagnosed.

[0055] The charge / discharge branch to be diagnosed is the target conducting charge / discharge branch, which can be determined based on the control signals provided by the controller 40 to the control terminals of each switching element. For example, the charge / discharge branch 21 in which both the charging switch CCB and the discharging switch DCB receive conduction signals is considered as the charge / discharge branch to be diagnosed. Exemplarily, the controller 40 can determine the number of target conducting charge / discharge branches 21 based on the target charge / discharge current value. During the operation of the battery system, the voltage sampling module AFE can collect the voltage on the shunt in each charge / discharge branch 21 in real time or at a preset sampling frequency, so that the controller 40 can obtain the branch current of each charge / discharge branch to be diagnosed in a timely manner based on the analog voltage in the voltage sampling module AFE when executing the switch fault diagnosis method.

[0056] S12. When at least two branch currents are not equal, for any charge / discharge branch to be diagnosed, if the branch current of the charge / discharge branch to be diagnosed is less than the first preset current, it is determined that the state control switch in the charge / discharge branch to be diagnosed has an open circuit fault.

[0057] Under the condition that all switching elements are fault-free, for any charging / discharging branch 21, when both the discharging switch DCB and the charging switch CCB are turned on, the charging / discharging branch 21 is turned on. The equivalent impedance of the charging / discharging branch 21 can be considered as the sum of the on-resistances of the discharging switch DCB and the charging switch CCB, which is a relatively small impedance. In the charging / discharging branch 21, a switching element that can disconnect the charging / discharging branch 21 when disconnected is defined as a state control switch; a switching element that can only increase the equivalent impedance of the charging / discharging branch 21 when disconnected, but cannot disconnect the charging / discharging branch 21, is defined as a non-state control switch. The state control switches and non-state control switches corresponding to the battery system in the charging and discharging states are opposite.

[0058] Specifically, the charging and discharging state of the battery system can be determined based on the current direction of each branch. When the current in each branch flows from the battery module 10 to the external device 30, the battery system is in a discharging state. At this time, turning off the discharge switch DCB disconnects the corresponding charging and discharging branch 21. Turning off the charging switch CCB allows the branch current in the corresponding charging and discharging branch 21 to flow through the body diode of the charging switch CCB. Since the impedance of the body diode is much greater than the on-resistance of the charging switch CCB, the equivalent impedance of the charging and discharging branch 21 increases. Therefore, in the discharging state, the state control switch in the charging and discharging branch 21 is the discharge switch DCB, and the non-state control switch is the charging switch CCB. When the current in each branch flows from the external device 30 to the battery assembly 10, the battery system is in a charging state. At this time, turning off the charging switch CCB disconnects the corresponding charging / discharging branch 21. Turning off the discharging switch DCB allows the branch current in the corresponding charging / discharging branch 21 to flow through the body diode of the discharging switch DCB. Since the impedance of the body diode is much greater than the on-resistance of the discharging switch DCB, the equivalent impedance of the charging / discharging branch 21 increases. Therefore, in the charging state, the state control switch in the charging / discharging branch 21 is the charging switch CCB, and the non-state control switch is the discharging switch DCB.

[0059] Similarly, during the charging and discharging process of a battery system, if the status control switch in the charging / discharging branch to be diagnosed has an open-circuit fault, the branch to be diagnosed will be disconnected, causing the branch current to approach zero. Therefore, during the charging and discharging process of the battery system, by monitoring the branch current in each charging / discharging branch to be diagnosed and determining the magnitude of each branch current, it is possible to determine whether the status control switch in each charging / discharging branch to be diagnosed has an open-circuit fault.

[0060] For example, the first preset current can be a value close to 0. Its specific value can be selected based on the error of the current detection result, the structure and model of the switching element, etc. For example, the first preset current can be set to be less than or equal to 1A. When the current of a certain branch is less than the first preset current, the charging and discharging branch to be diagnosed can be considered to be in an open state. Therefore, it can be determined that the status control switch in the charging and discharging branch to be diagnosed has an open circuit fault.

[0061] In summary, when the battery system is in a discharging state, online diagnosis of open-circuit faults in the discharge switch (DCB) of each target conducting branch can be achieved; when the battery system is in a charging state, online diagnosis of open-circuit faults in the charging switch (CCB) of each target conducting branch can be achieved. Combining the diagnostic results from both charging and discharging states, a comprehensive diagnosis of all switching elements in the battery system can be realized.

[0062] It should be noted that the branch current mentioned here, as well as the main current mentioned later, represent the magnitude of the current, regardless of its direction. That is, in the discharge state, the aforementioned current refers to the magnitude of the discharge current flowing from the battery pack 10 to the external device 30; in the charging state, the aforementioned current refers to the magnitude of the charging current flowing from the external device 30 to the battery pack 10. For example, when the positive direction of the current in the battery system is specified, the absolute value of the current can be used to represent the magnitude of the current. For instance, when the positive direction of the current is specified as flowing from the external device 30 to the battery pack 10, the charging current of the battery system is positive. In the charging state, the charging current can be directly used as the current required in this diagnostic method; in the discharge state, the absolute value of the discharge current can be used as the current required in this diagnostic method.

[0063] The battery system switch fault diagnosis method provided in this invention obtains the branch current of each charge / discharge branch to be diagnosed in the battery system, and determines whether the state control switch in each charge / discharge branch to be diagnosed has an open circuit fault based on the magnitude of the branch current. When the branch current is less than a first preset current, it indicates that the branch current is close to zero, and the charge / discharge branch to be diagnosed is close to an open circuit. Therefore, it can be determined that the state control switch in the charge / discharge branch to be diagnosed has an open circuit fault. Since the corresponding state control switches are different in the charging state and the discharging state, by combining the diagnosis results in the charging state and the discharging state, this invention can effectively diagnose open circuit faults of each switching element in a multi-parallel structure. Furthermore, this invention directly diagnoses switch faults based on current data, without sending other control signals to each switching element during the test, without testing in a specific scenario, and without changing the operating state of the battery system. Therefore, it can achieve real-time online fault diagnosis of each switching element. In addition, the first preset current involved in this invention can be calibrated according to the actual circuit configuration and application scenario, making this invention highly compatible and widely applicable.

[0064] Figure 3 This is a flowchart illustrating another battery system switch fault diagnosis method provided in an embodiment of the present invention. See also... Figure 3 The switch fault diagnosis method includes the following steps:

[0065] S110. Determine the charge / discharge branch to be diagnosed in the charge / discharge assembly, and obtain the branch current in each charge / discharge branch to be diagnosed.

[0066] S120. When at least two branch currents are not equal, for any charge / discharge branch to be diagnosed, determine whether the branch current of the charge / discharge branch to be diagnosed is less than the first preset current; if yes, then execute S130; if no, then execute S140.

[0067] As analyzed in the above embodiments, the magnitude of the branch current is negatively correlated with the equivalent impedance of the charge / discharge branch to be diagnosed. During the charging and discharging process of the battery system, when the state control switch in the charge / discharge branch to be diagnosed has an open-circuit fault, the charge / discharge branch to be diagnosed will be disconnected, causing the equivalent impedance of the charge / discharge branch to be diagnosed to approach infinity, and the branch current of the charge / discharge branch to be diagnosed to approach 0. When the non-state control switch in the charge / discharge branch to be diagnosed has an open-circuit fault, the equivalent impedance of the charge / discharge branch to be diagnosed will increase, causing the branch current flowing through the charge / discharge branch to be diagnosed to decrease.

[0068] Based on the above current characteristics, during the charging and discharging process of the battery system, by monitoring the branch current in each charging and discharging branch to be diagnosed, judging the magnitude of each branch current, and comparing the relationship between the branch currents, it is possible to determine whether there is an open circuit fault in the state control switch in each charging and discharging branch to be diagnosed, and also to determine whether there is an open circuit fault in the non-state control switch in each charging and discharging branch to be diagnosed.

[0069] When the currents in at least two charge / discharge branches to be diagnosed are unequal, the equivalent impedances of these two branches are different. The branch with the smaller current will have a larger equivalent impedance. Therefore, the discharge switch DCB and / or charging switch CCB in this branch to be diagnosed have an open-circuit fault. The following section provides a detailed explanation of the methods for determining faults in various switching components.

[0070] S130. It is determined that the status control switch in the charging / discharging branch to be diagnosed has an open circuit fault.

[0071] The principle behind this determination can be found in the explanation in S12, and will not be repeated here.

[0072] S140. When the branch current of the charging / discharging branch to be diagnosed is greater than the second preset current, and there are other charging / discharging branches to be diagnosed whose branch current exceeds a preset multiple of the branch current of the charging / discharging branch to be diagnosed, it is determined that the non-state control switch in the charging / discharging branch to be diagnosed has an open circuit fault.

[0073] This step can be broken down into the following steps: determining whether the branch current of the charging / discharging branch is greater than the second preset current; if so, determining whether there are other charging / discharging branches whose branch current exceeds a preset multiple of the branch current of the charging / discharging branch to be diagnosed; if so, determining that the non-state control switch in the charging / discharging branch to be diagnosed has an open-circuit fault. If the result of any of these determination steps is negative, the switching element in the charging / discharging branch to be diagnosed is considered fault-free, and other undiagnosed charging / discharging branches to be diagnosed are selected for fault diagnosis.

[0074] The first preset current is set to determine whether the charging / discharging branch is close to an open circuit, so its value is relatively small. However, when the non-state control switch has an open circuit fault, there is actually a certain branch current in the faulty charging / discharging circuit 21, and the branch current under the non-state control switch open circuit fault is much larger than the branch current under the state control switch open circuit fault. Therefore, by setting the second preset current to be greater than the first preset current, when the current branch current is greater than the second preset current, it can be determined that a certain amount of current is indeed flowing in the charging / discharging branch to be diagnosed. Based on this, it can be preliminarily determined that the state control switch in the charging / discharging branch to be diagnosed does not have an open circuit fault. On this basis, since there is a multiple relationship between the branch current in the normal charging / discharging branch and the branch current under the non-state control switch open circuit fault (this multiple relationship is related to, for example, the multiple relationship between the impedance of the body diode and the conduction impedance of the switching element); by further determining the multiple relationship between this branch current and other branch currents, it is possible to accurately determine whether the non-state control switch of the charging / discharging branch to be diagnosed has an open circuit fault. Specifically, when the current in this branch is less than the current in other branches, especially when the current in other branches is greater than a preset multiple of this branch circuit, the effects of device impedance drift caused by device aging or parameter drift, as well as measurement errors, can be ruled out. This confirms that the equivalent impedance of the charge / discharge branch to be diagnosed with the smaller current is indeed larger, and therefore it can be determined that the non-state control switch in the charge / discharge branch to be diagnosed has an open circuit fault. The preset multiple is a multiple greater than 1, preferably greater than or equal to three times.

[0075] For example, the preset multiplier can be selected based on the relationship between the on-resistance of the switching element and the impedance of the body diode in the switching element. Generally speaking, the impedance of the body diode is much greater than the on-resistance of the switching element, for example, more than ten times. However, considering the applicability of this method, the preset multiplier should not be set too large, so as to ensure that an open-circuit fault in a non-state-controlled switch can be detected even when the impedance of the body diode is relatively small. For example, considering both the reliability of the diagnostic results and the applicability of the diagnostic method, the preset multiplier can be set between three and ten times.

[0076] For example, the second preset current can be selected based on the target current in the charging / discharging circuit, the number of charging / discharging branches to be diagnosed, the on-resistance of each switching element and the impedance of its body diode, and the value of the first preset current. The second preset current can be greater than the first preset current, for example, greater than or equal to 3A; or, to simplify the diagnostic logic and reduce the number of comparison steps, the second preset current can be set to be equal to the first preset current, for example, equal to 1A.

[0077] The battery system switch fault diagnosis method provided in this invention obtains the branch current of each charge / discharge branch to be diagnosed in the battery system, and determines whether each switching element in each charge / discharge branch to be diagnosed has an open circuit fault based on the magnitude relationship between the branch currents. Specifically, when the branch current is close to zero, it indicates that the equivalent impedance of the charge / discharge branch to be diagnosed is close to infinity, and the charge / discharge branch to be diagnosed is close to an open circuit. Therefore, it can be determined that the state control switch in the charge / discharge branch to be diagnosed has an open circuit fault. When the branch current is greater than a second preset current, and there are other branch currents that exceed a preset multiple of the branch current, it indicates that the equivalent impedance of the charge / discharge branch to be diagnosed has increased to a certain extent compared with the normal situation. Based on this, it can be determined that the non-state control switch in the charge / discharge branch to be diagnosed has an open circuit fault. The first preset current, the second preset current, and the preset multiple can all be calibrated according to the actual circuit configuration and application scenario.

[0078] Figure 4 This is a schematic flowchart of another battery system switch fault diagnosis method provided in an embodiment of the present invention. See also Figure 4 The specific methods for diagnosing switch faults include:

[0079] S201. Obtain the main circuit current and determine the charge / discharge branch to be diagnosed in the charge / discharge assembly.

[0080] The main circuit current is the current between the battery module 10 and the external device 30, which is the total current in the battery system's charging and discharging circuit, or the sum of the currents in each charging and discharging branch to be diagnosed. Specifically, the current between the battery module 10 and the first connection terminal N1, or the current between the second connection terminal N2 and the external device 30, or the current on the path directly connecting the battery module 10 and the external device 30 can be collected as the main circuit current.

[0081] For example, the charging and discharging state of the battery system can also be determined based on the direction of the main circuit current. The determination method can be found in the determination method based on the branch circuit current, and will not be repeated here.

[0082] S202. Determine if the main circuit current is 0; if yes, proceed to S203; if no, proceed to S205.

[0083] When the main circuit current is 0, the following situations may exist: First, the battery module 10 is fully charged or fully discharged, so there is no current in the entire charging / discharging circuit. Second, there is no charging / discharging demand at this time, so no charging / discharging current is required. Third, the system has a charging / discharging demand, and the battery module 10 / external device 30 can provide power, but the status control switches in each charging / discharging circuit to be diagnosed have open-circuit faults, causing each charging / discharging circuit to be diagnosed to be open-circuited. In the aforementioned two situations, if each charging / discharging circuit to be diagnosed is fault-free, there is basically no voltage difference or a small voltage difference between the first connection terminal N1 and the second connection terminal N2; however, when the status control switches in each charging / discharging circuit to be diagnosed have open-circuit faults, there is a large voltage difference between the first connection terminal N1 and the second connection terminal N2. Therefore, the fault state of each switching element can be determined based on the voltage difference between the first connection terminal N1 and the second connection terminal N2.

[0084] S203. Determine whether the difference between the positive voltage of the battery module and the positive voltage of the external device is greater than the preset voltage difference; if yes, proceed to S204; if no, return to S201.

[0085] In this configuration, the positive voltage V_bat of the battery assembly 10 is the voltage of the first connection terminal N1, and the positive voltage V_bus of the external device 30 is the voltage of the second connection terminal N2. For example, the preset voltage difference can be determined based on parameters such as the on-resistance of each switching element, the number of charging / discharging branches to be diagnosed, and the target main circuit current; for example, it can be greater than or equal to 0.3V.

[0086] S204. It is determined that the status control switches in all the charging and discharging branches to be diagnosed have open circuit faults.

[0087] For example, after this step is completed, S201 can be executed to proceed to the next round of diagnosis.

[0088] S205. Obtain the branch current in each charging / discharging branch to be diagnosed.

[0089] When the main circuit current is not zero, it indicates that there is a conducting charging / discharging branch to be diagnosed. Therefore, we can proceed to the step of judging whether each switching element has an open circuit fault based on the branch current.

[0090] S206. Determine whether the current in each branch is equal; if yes, proceed to S207; if no, proceed to S208.

[0091] For example, suppose the number of charging and discharging branches to be diagnosed is n, where n > 1. This step can also be to determine whether the current in each branch is 1 / n of the current in the main circuit.

[0092] S207. Determine that there is no open circuit fault in the status control switches of all the charging and discharging branches to be diagnosed.

[0093] When the current in each branch is equal, it indicates that the equivalent impedance of each branch to be diagnosed is equal. Therefore, it can be preliminarily determined that the state control switches in each charge / discharge branch to be diagnosed have no open-circuit faults. For non-state control switches in each charge / discharge branch to be diagnosed, the judgment can be made after changing the charge / discharge state of the battery system. For example, after this step is completed, S201 can be executed to perform the next round of diagnosis.

[0094] S208. Select a charging / discharging branch to be diagnosed.

[0095] Specifically, this step can be to arbitrarily select one charge / discharge branch to be diagnosed from among the charge / discharge branches that have not yet been diagnosed in this round of diagnosis.

[0096] S209. Determine whether the absolute value of the current of the currently selected branch is less than the preset current; if yes, execute S210; if no, execute S211.

[0097] In this embodiment, the first preset current and the second preset current are set to the same preset current value.

[0098] S210. It is determined that the status control switch in the charging / discharging branch to be diagnosed has an open circuit fault.

[0099] After this step is completed, S213 can be executed to perform fault diagnosis of other charging and discharging branches 21 in this round of diagnosis.

[0100] S211. Determine whether there are other charging / discharging branches whose absolute values ​​of branch current exceed a preset multiple of the absolute value of the currently selected charging / discharging branch whose absolute value of branch current exceeds a preset multiple. If yes, execute S212; otherwise, execute S213.

[0101] S212. Determine that the non-state control switch in the charging / discharging branch to be diagnosed has an open circuit fault.

[0102] After this step is completed, S213 can be executed to perform fault diagnosis of other charging and discharging branches 21 in this round of diagnosis.

[0103] S213. Determine whether the diagnosis of all charging and discharging branches to be diagnosed has been completed; if yes, return to execute S201; if no, return to execute S208.

[0104] Specifically, if the absolute value of the branch current of no other charge / discharge branch to be diagnosed exceeds a preset multiple of the absolute value of the branch current of the currently selected charge / discharge branch to be diagnosed, it can be determined that neither the charging switch CCB nor the discharging switch DCB in the currently selected charge / discharge branch to be diagnosed has an open circuit fault.

[0105] When all switching elements in the charging and discharging branches to be diagnosed have been diagnosed, the current round of diagnosis ends, and the process can return to execute S201 to proceed to the next round of diagnosis.

[0106] This embodiment implements battery system switch fault diagnosis through steps S201-S213. For example, the battery system can be an on-board battery system, and the external device 30 can be an on-board load and / or an on-board charger. The switch fault diagnosis method provided by this embodiment can perform real-time open-circuit diagnosis of each discrete MOSFET regardless of the vehicle's operating conditions. Furthermore, this embodiment is applicable to almost all solutions that use MOSFETs as battery system charge / discharge switches.

[0107] It should be noted that, Figure 4 The method steps shown are merely illustrative of the present invention and are not intended to limit the invention. In other embodiments, steps can be added or removed, and the order of steps can be adjusted, according to actual needs. For example, the diagnostic process for multiple charge / discharge branches to be diagnosed can be performed simultaneously.

[0108] The following section uses the example of a charging / discharging assembly 20 containing two charging / discharging branches to illustrate the specific application steps of this switch fault diagnosis method.

[0109] Figure 5 This is a schematic diagram of another battery system provided in an embodiment of the present invention. See also... Figure 5 The discharge switch in the first charging / discharging branch 211 is labeled DCB_A, the charging switch is labeled CCB_A, and the shunt is labeled Shunt_A. The discharge switch in the second charging / discharging branch 212 is labeled DCB_B, the charging switch is labeled CCB_B, and the shunt is labeled Shunt_B to distinguish them.

[0110] Figure 6 This is a schematic flowchart of another battery system switch fault diagnosis method provided in an embodiment of the present invention. See also Figure 6 The specific steps of this switch fault diagnosis method are as follows:

[0111] S301, Obtain I

[0112] Where I is the main circuit current.

[0113] S302. Determine if I = 0. If yes, proceed to S303; otherwise, proceed to S305.

[0114] S303. Determine if |V_bat-V_bus| > 0.3V. If yes, execute S304; otherwise, execute S301.

[0115] S304, DCB_A, CCB_A, DCB_B, and CCB_B are all open circuits.

[0116] S305. Determine if I < 0. If yes, proceed to S306; otherwise, proceed to S316.

[0117] This step is equivalent to determining the charge / discharge state of the battery system. Here, the positive direction of current is defined as the flow from external device 30 to battery assembly 10. Therefore, I < 0 indicates a discharge state, and vice versa for a charging state. Accordingly, this embodiment provides specific determination steps for both the charging and discharging states. S306-S315 are diagnostic steps for the discharge state; S316-S325 are diagnostic steps for the charging state.

[0118] S306. Obtain IA and IB.

[0119] Wherein, IA is the branch current in the first charging / discharging branch 211, and IB is the branch current in the second charging / discharging branch 212.

[0120] S307. Determine if IA = IB. If yes, execute S301; otherwise, execute S308.

[0121] S308. Determine if IA < -3A & IB > -1A. If yes, proceed to S309; ​​otherwise, proceed to S310.

[0122] This step is equivalent to determining whether IA is close to 1 and whether IB is close to 0.

[0123] S309, DCB_B open circuit.

[0124] When IB approaches 0, it indicates that the second charging / discharging branch 212 is open. Since it is in a discharging state at this time, it can be determined that the discharge switch DCB_B is open.

[0125] S310. Determine if IB < -3A & IA > -1A. If yes, execute S311; otherwise, execute S312.

[0126] This step is equivalent to determining whether IB is close to I and whether IA is close to 0.

[0127] S311, DCB_A open circuit.

[0128] When IA approaches 0, it indicates that the first charging / discharging branch 211 is open. Since it is in a discharging state at this time, it can be determined that the discharge switch DCB_A is open.

[0129] S312. Determine if IA < 3IB & IB < -3A. If yes, execute S313; otherwise, execute S314.

[0130] This step is equivalent to determining whether there is a certain current in IB (the current magnitude is greater than 3A) and whether the magnitude of IA is greater than three times that of IB.

[0131] S313, CCB_B open circuit.

[0132] In the discharge state, when the charging switch CCB_B is open, current can flow through the body diode of the charging switch CCB_B. However, because the body diode has impedance, which is much greater than the on-resistance of each charging and discharging switch, the equivalent impedance of the first charging / discharging branch 211 is much smaller than the equivalent impedance of the second charging / discharging branch 212. This results in current flowing in both the first and second charging / discharging branches 211 and 212, with IA being much larger than IB. Therefore, when IA < 3IB & IB < -3A, it can be determined that CCB_B is open.

[0133] S314. Determine if IB < 3IA & IA < -3A. If yes, execute S315; otherwise, execute S301.

[0134] This step is equivalent to determining whether there is a certain current in IA (the current magnitude is greater than 3A) and whether the magnitude of IB is greater than three times that of IA.

[0135] S315, CCB_A open circuit.

[0136] In the discharge state, when the charging switch CCB_A is open, current can flow through the body diode of the charging switch CCB_A. However, because the body diode has impedance, which is much greater than the on-resistance of each charging and discharging switch, the equivalent impedance of the first charging / discharging branch 211 is much greater than the equivalent impedance of the second charging / discharging branch 212. This results in current flowing in both the first charging / discharging branch 211 and the second charging / discharging branch 212, and the magnitude of IA is much smaller than the magnitude of IB. Therefore, when IB < 3IA & IA < -3A, it can be determined that CCB_A is open.

[0137] S316. Obtain IA and IB.

[0138] S317. Determine if IA = IB. If yes, execute S301; otherwise, execute S318.

[0139] S318. Determine if IA > 3A & IB < 1A. If yes, execute S319; otherwise, execute S320.

[0140] S319, CCB_B open circuit.

[0141] S320. Determine if IB > 3A & IA < 1A. If yes, execute S321; otherwise, execute S322.

[0142] S321, CCB_A open circuit

[0143] S322. Determine if IA > 3IB & IB > 3A. If yes, execute S323; otherwise, execute S324.

[0144] S323, DCB_B open circuit.

[0145] S324. Determine if IB > 3IA & IA > 3A. If yes, execute S325; otherwise, execute S301.

[0146] S325, DCB_A open circuit.

[0147] The diagnostic steps in the charging state are basically the same as those in the discharging state, with the main difference being that in the charging state, I is a positive value, and the state control switch is the charging switch, while the non-state control switch is the discharging switch. Therefore, the diagnostic steps in the charging state can be explained by referring to the explanation of the diagnostic steps in the discharging state, and will not be repeated here.

[0148] This embodiment implements switch fault diagnosis for a battery system with two charge / discharge branches through steps S301-S325. It should be noted that... Figure 6 The method steps shown are merely illustrative of the present invention and are not intended to limit the invention. In other embodiments, steps can be added or removed, and the order of steps can be adjusted according to actual needs. For example, in the discharge state, steps S308, S310, S312, and S314 can be performed simultaneously; or, steps S308 and S310 can be performed simultaneously, with step S312 executed after step S308 and step S314 executed after step S310. Corresponding adjustments can also be made in the charging state. In addition, diagnostic stop conditions can be set. For example, after a round of diagnosis is completed, it is first determined whether the diagnostic stop conditions are met. If yes, the diagnosis stops; if no, the process returns to the first step for the next round of diagnosis.

[0149] This invention also provides a battery system switch fault diagnosis device, used to execute the battery system switch fault diagnosis method provided in any embodiment of this invention, and has the corresponding functional modules and beneficial effects of the method execution. Figure 7 This is a schematic diagram of a battery system switch fault diagnosis device provided in an embodiment of the present invention. See also... Figure 7 The battery system switch fault diagnosis device includes: a current acquisition module 610 and a first determination module 620.

[0150] The current acquisition module 610 is used to identify the charge / discharge branch to be diagnosed in the charge / discharge assembly and acquire the branch current in each charge / discharge branch to be diagnosed. The first determination module 620 is used to determine that the state control switch in the charge / discharge branch to be diagnosed has an open circuit fault when at least two branch currents are not equal, and the branch current of any charge / discharge branch to be diagnosed is less than a first preset current. Specifically, when the battery system is in a discharging state, the state control switch is a discharge switch; when the battery system is in a charging state, the state control switch is a charging switch.

[0151] Based on the above embodiments, optionally, the battery system switch fault diagnosis device further includes: a second determination module, used to determine that the non-state control switch in the charge / discharge branch to be diagnosed has an open circuit fault when at least two branch currents are not equal, for any charge / discharge branch to be diagnosed, if the branch current of the charge / discharge branch to be diagnosed is greater than a second preset current, and there are other charge / discharge branches to be diagnosed whose branch current exceeds a preset multiple of the branch current of the charge / discharge branch to be diagnosed. Wherein, the second preset current is greater than or equal to the first preset current; when the battery system is in a discharging state, the non-state control switch is a charging switch; when the battery system is in a charging state, the non-state control switch is a discharging switch.

[0152] Based on the above embodiments, optionally, the current acquisition module 610 is further configured to acquire the main circuit current before acquiring the branch current in each charge / discharge branch to be diagnosed; wherein, the main circuit current is the current between the battery module and the external device. The battery system switch fault diagnosis device further includes a main circuit current judgment module, configured to determine whether the main circuit current is 0; if so, when the difference between the positive voltage of the battery module and the positive voltage of the external device is greater than a preset voltage difference, it is determined that the state control switch in all charge / discharge branches to be diagnosed has an open circuit fault; if not, the current acquisition module 610 can perform the step of acquiring the branch current in each charge / discharge branch to be diagnosed.

[0153] Based on the above embodiments, optionally, the current acquisition module 610 is specifically used to take the charging and discharging branch where both the charging switch and the discharging switch receive the conduction signal as the charging and discharging branch to be diagnosed, and to determine the branch current in the charging and discharging branch to be diagnosed based on the voltage across the shunt and the resistance of the shunt.

[0154] Based on the above embodiments, optionally, the battery system switch fault diagnosis device further includes: a state determination module, used to determine the charging and discharging state of the battery system based on the current direction of the main circuit current and / or the branch circuit current. Specifically, it is used to determine that the battery system is in a discharging state when the main circuit current and / or the branch circuit current flows from the battery pack to the external device; and to determine that the battery system is in a charging state when the main circuit current and / or the branch circuit current flows from the external device to the battery pack.

[0155] This invention also provides a battery system, the structure of which can be found in [reference needed]. Figure 1 The battery system may specifically include: a battery assembly 10, a controller 40, and a charging / discharging assembly 20 connected between the battery assembly 10 and an external device 30; the charging / discharging assembly 20 includes multiple parallel charging / discharging branches 21, each of which includes a charging switch CCB and a discharging switch DCB connected in series. The controller 40 is electrically connected to the control terminals of each charging switch CCB and each discharging switch DCB, respectively; the controller 40 is used to execute the battery system switch fault diagnosis method provided in any embodiment of the present invention, and has corresponding beneficial effects.

[0156] For example, the controller 40 includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the battery system switching fault diagnosis method provided in any embodiment of the present invention.

[0157] Figure 8 This is a schematic diagram of the structure of a controller provided in an embodiment of the present invention. See also... Figure 8 , Figure 8 The components in the controller 40 shown, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the invention described and / or claimed herein.

[0158] like Figure 8As shown, the controller 40 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 or a random access memory (RAM) 13, communicatively connected to the at least one processor 11. The memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded from storage unit 18 into the RAM 13. The RAM 13 can also store various programs and data required for the operation of the controller 40. The processor 11, ROM 12, and RAM 13 are interconnected via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0159] Multiple components in the controller 40 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, optical disk, etc.; and a communication unit 19, such as a network card, modem, wireless transceiver, etc. The communication unit 19 allows the controller 40 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0160] Processor 11 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as a method for diagnosing switching faults in a battery system.

[0161] In some embodiments, the battery system switching fault diagnosis method may be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program may be loaded and / or installed on controller 40 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by processor 11, one or more steps of the battery system switching fault diagnosis method described above may be performed. Alternatively, in other embodiments, processor 11 may be configured to perform the battery system switching fault diagnosis method by any other suitable means (e.g., by means of firmware).

[0162] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0163] Computer programs used to implement the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0164] In the context of this invention, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0165] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0166] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or computing systems that include middleware components (e.g., application servers), or computing systems that include frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0167] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0168] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0169] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for diagnosing switch faults in a battery system, characterized in that, The battery system includes a battery module and a charging / discharging module connected between the battery module and an external device; the charging / discharging module includes multiple parallel charging / discharging branches, and each charging / discharging branch includes a charging switch and a discharging switch connected in series. The battery system switching fault diagnosis method includes: The charging and discharging branch to be diagnosed in the charging and discharging assembly is determined, and the branch current in each charging and discharging branch to be diagnosed is obtained; wherein, the charging and discharging branch in which both the charging switch and the discharging switch receive the on signal is taken as the charging and discharging branch to be diagnosed. When at least two of the branch currents are not equal, for any charge / discharge branch to be diagnosed, if the branch current of the charge / discharge branch to be diagnosed is less than the first preset current, it is determined that the state control switch in the charge / discharge branch to be diagnosed has an open circuit fault. Wherein, when the battery system is in a discharging state, the state control switch is the discharge switch; when the battery system is in a charging state, the state control switch is the charging switch. When at least two of the branch currents are not equal, the method further includes: For any charge / discharge branch to be diagnosed, if the branch current of the charge / discharge branch to be diagnosed is greater than the second preset current, and there are other charge / discharge branches to be diagnosed whose branch current exceeds a preset multiple of the branch current of the charge / discharge branch to be diagnosed, it is determined that the non-state control switch in the charge / discharge branch to be diagnosed has an open circuit fault. Wherein, the second preset current is greater than or equal to the first preset current; the charging switch and the discharging switch use switching elements with the same structure, and the preset multiple is a multiple greater than 1. The preset multiple is selected in combination with the relationship between the on-resistance of the switching element and the impedance of the body diode in the switching element; when the battery system is in the discharging state, the non-state control switch is the charging switch; when the battery system is in the charging state, the non-state control switch is the discharging switch.

2. The method for diagnosing switch faults in a battery system according to claim 1, characterized in that, Before obtaining the branch current in each of the described charge / discharge branches to be diagnosed, the method further includes: Obtain the main circuit current; wherein, the main circuit current is the current between the battery assembly and the external device; Determine whether the main circuit current is 0; If so, when the difference between the positive voltage of the battery assembly and the positive voltage of the external device is greater than a preset voltage difference, it is determined that the status control switch in all the charging and discharging branches to be diagnosed has an open circuit fault. If not, then perform the step of obtaining the branch current in each of the charging and discharging branches to be diagnosed.

3. The method for diagnosing switch faults in a battery system according to claim 2, characterized in that, The charging and discharging state of the battery system is determined based on the current direction of the main circuit and / or the current direction of the branch circuit. When the main circuit current and / or the branch circuit current flows from the battery assembly to the external device, the battery system is in a discharging state; The battery system is in a charging state when the main circuit current and / or the branch circuit current flows from the external device to the battery assembly.

4. The method for diagnosing switch faults in a battery system according to claim 2, characterized in that, The preset multiple is greater than or equal to three times.

5. The method for diagnosing switch faults in a battery system according to claim 1, characterized in that, The first preset current is less than or equal to 1A.

6. The method for diagnosing switch faults in a battery system according to claim 1, characterized in that, Identifying the charge / discharge branch to be diagnosed in the charge / discharge assembly includes: The charging / discharging branch in which both the charging switch and the discharging switch receive a conduction signal is taken as the charging / discharging branch to be diagnosed.

7. The method for diagnosing switch faults in a battery system according to claim 1, characterized in that, The charging and discharging branch further includes a shunt connected in series with the charging switch and the discharging switch; Obtaining the branch current in the charge / discharge branch to be diagnosed includes: The branch current in the charge / discharge branch to be diagnosed is determined based on the voltage across the shunt and the resistance of the shunt.

8. A battery system switch fault diagnosis device, characterized in that, include: The current acquisition module is used to determine the charge / discharge branch to be diagnosed in the charge / discharge assembly and acquire the branch current in each charge / discharge branch to be diagnosed; wherein, the charge / discharge branch in which both the charging switch and the discharging switch receive the on signal is taken as the charge / discharge branch to be diagnosed. The first determination module is used to determine that the state control switch in the charging and discharging branch to be diagnosed has an open circuit fault when the branch current of the charging and discharging branch to be diagnosed is less than the first preset current, when at least two of the branch currents are not equal. Wherein, when the battery system is in a discharging state, the state control switch is the discharge switch; when the battery system is in a charging state, the state control switch is the charging switch. The battery system switch fault diagnosis device also includes: a second determination module, used to determine that the non-state control switch in the charge-discharge branch to be diagnosed has an open circuit fault when at least two branch currents are not equal, for any charge-discharge branch to be diagnosed, when the branch current of the charge-discharge branch to be diagnosed is greater than the second preset current, and there are other charge-discharge branches to be diagnosed whose branch current exceeds a preset multiple of the branch current of the charge-discharge branch to be diagnosed. The second preset current is greater than or equal to the first preset current; the charging switch and the discharging switch use switching elements with the same structure, and the preset multiple is a multiple greater than 1. The preset multiple is selected in combination with the relationship between the on-resistance of the switching element and the impedance of the body diode in the switching element; when the battery system is in the discharging state, the non-state control switch is the charging switch; when the battery system is in the charging state, the non-state control switch is the discharging switch.

9. A battery system, characterized in that, include: A battery assembly, a controller, and a charging / discharging assembly connecting the battery assembly and an external device; the charging / discharging assembly includes multiple parallel charging / discharging branches, each of which includes a charging switch and a discharging switch connected in series. The controller is electrically connected to the control terminal of each of the charging switches and the control terminal of each of the discharging switches, respectively. The controller includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the battery system switching fault diagnosis method according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that, when executed by a processor, implement the switching fault diagnosis method for the battery system according to any one of claims 1-7.

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