Battery system and method of forced charge and discharge thereof

Abstract

The application discloses a battery system and a forced charging and discharging method thereof, and belongs to the technical field of batteries. The method is executed by a control component; the method comprises the following steps: when a forced control instruction issued by an energy storage converter is received, and the alarm level of a voltage fault in a battery component is within a preset alarm level range, closing a fault protection operation corresponding to the voltage fault in the preset alarm level range, and starting a forced charging and discharging operation; the fault protection operation corresponding to the voltage fault in the preset alarm level range comprises: controlling a switch component to be disconnected; the forced charging and discharging operation comprises: controlling the switch component to be turned on, so that the energy storage converter can execute a preset action on the battery component through a total positive end and a total negative end. According to the application, the efficiency of forced charging and discharging of the battery system can be improved, and the cost can be reduced on the basis of ensuring the reliability of the battery system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery, in particular to a battery system and a forced charging and discharging method thereof. BACKGROUND

[0002] At present, for a battery system composed of at least one battery pack, overcharging / overdischarging of the battery pack may occur during actual use or testing of the battery system. In a common protection strategy, in order to protect the system, the charging and discharging circuit of the battery system is cut off when an alarm protection is triggered. At this time, if the battery system needs to be charged and discharged, the original charging and discharging circuit cannot be used, the battery pack needs to be disassembled, and an external charger or load needs to be used to charge and discharge each battery pack. However, the charging and discharging efficiency is low, the cost is high, and the system reliability is affected when the battery pack is disassembled for charging and discharging. SUMMARY

[0003] The present application provides a battery system and a forced charging and discharging method thereof, so as to improve the efficiency of forced charging and discharging of the battery system and reduce the cost on the basis of ensuring the reliability of the battery system.

[0004] In a first aspect, the present application provides a forced charging and discharging method of a battery system, the battery system comprising: a battery assembly, a switch assembly, a control assembly and an energy storage converter; the battery assembly and the switch assembly are connected in series between a total positive terminal and a total negative terminal of the battery system, the control assembly is connected to the battery assembly, the switch assembly and the energy storage converter respectively; the energy storage converter is further connected to the total positive terminal and the total negative terminal respectively; the forced charging and discharging method of the battery system is executed by the control assembly; the forced charging and discharging method of the battery system comprises:

[0005] when the forced control instruction issued by the energy storage converter is received, and the alarm level of the voltage fault in the battery assembly is within a preset alarm level range, the fault protection operation corresponding to the voltage fault in the preset alarm level range is closed, and a forced charging and discharging operation is started; wherein the fault protection operation corresponding to the voltage fault in the preset alarm level range comprises: controlling the switch assembly to be disconnected; the forced charging and discharging operation comprises: controlling the switch assembly to be turned on, so that the energy storage converter can execute a preset action on the battery assembly through the total positive terminal and the total negative terminal;

[0006] wherein, when the forced control instruction is a forced charging instruction, the voltage fault is an under-voltage fault, and the preset action is charging; when the forced control instruction is a forced discharging instruction, the voltage fault is an over-voltage fault, and the preset action is discharging.

[0007] Optionally, after the voltage fault corresponding to the preset alarm level range is closed and the forced charging and discharging operation is started, the method further comprises:

[0008] counting an action duration corresponding to the preset action;

[0009] when the action duration exceeds a preset duration, determining whether the preset action actually occurs according to the electrical parameter of the battery assembly;

[0010] when the action duration does not exceed the preset duration, continuing to execute the forced charging and discharging operation;

[0011] If the preset action actually occurs, the forced charging and discharging method of the battery system further comprises: starting the fault protection operation corresponding to the voltage fault in the preset alarm level range, and waiting to receive the forced control end instruction corresponding to the forced control instruction issued by the energy storage converter;

[0012] If the preset action does not actually occur, the forced charging and discharging method of the battery system further comprises: starting the fault protection operation corresponding to the voltage fault in the preset alarm level range, and waiting to receive the forced control instruction issued by the energy storage converter next time.

[0013] Optionally, the battery assembly comprises a plurality of battery cells connected in series between the positive electrode and the negative electrode of the battery assembly, and the electrical parameter of the battery assembly comprises: a maximum voltage in the single battery voltage of each battery cell, and an action current flowing through the battery assembly.

[0014] Determining whether the preset action actually occurs according to the electrical parameter of the battery assembly comprises:

[0015] When the maximum voltage meets a voltage preset condition, and / or the action current meets a current preset condition, it is determined that the preset action actually occurs;

[0016] When the maximum voltage does not meet the voltage preset condition, and the action current does not meet the current preset condition, it is determined that the preset action does not actually occur.

[0017] Optionally, when the forced control instruction is a forced charging instruction, the maximum voltage is the minimum voltage in the single battery voltage of each battery cell, and the action current is a charging current; the voltage preset condition is that the minimum voltage is greater than a first voltage threshold; and the current preset condition is that the charging current is greater than a first current value and the duration of the charging current is greater than a first preset time.

[0018] The forced control instruction is a forced discharge instruction, the extreme value voltage is the highest voltage among the single voltages of the battery cells, and the action current is a discharge current; the voltage preset condition is that the highest voltage is less than a second voltage threshold; the current preset condition is that the discharge current is greater than a second current value and a duration of the discharge current is greater than a second preset time; and the second voltage threshold is greater than the first voltage threshold.

[0019] Optionally, before the starting of the forced charging and discharging operation, the method further comprises:

[0020] determining whether a forced control end instruction corresponding to the forced control instruction issued by the energy storage converter is received;

[0021] If yes, the forced charging and discharging operation is stopped, and a fault protection operation corresponding to a voltage fault in the preset alarm level range is started;

[0022] If no, the forced charging and discharging operation is started, and an action duration corresponding to the preset action is counted;

[0023] Correspondingly, when the action duration does not exceed the preset duration, the step of determining whether the forced control end instruction corresponding to the forced control instruction issued by the energy storage converter is received is returned to.

[0024] Optionally, the battery assembly comprises a plurality of battery cells connected in series between a positive electrode and a negative electrode of the battery assembly.

[0025] The under-voltage fault comprises a single battery cell under-voltage fault and a total battery assembly under-voltage fault.

[0026] The over-voltage fault comprises a single battery cell over-voltage fault and a total battery assembly over-voltage fault.

[0027] And / or,

[0028] The alarm levels of the voltage faults in the battery assembly comprise at least three alarm levels; wherein the number of alarm levels is positively correlated with the severity of the voltage faults.

[0029] The preset alarm level range comprises alarm levels other than the first and last alarm levels.

[0030] In a second aspect, the embodiments of the present application also provide a forced charging and discharging method of a battery system, the battery system comprising: a battery assembly, a switch assembly, a control assembly and an energy storage converter; the battery assembly and the switch assembly are connected in series between a total positive terminal and a total negative terminal of the battery system, the control assembly is connected to the battery assembly, the switch assembly and the energy storage converter respectively; the energy storage converter is further connected to the total positive terminal and the total negative terminal respectively; the forced charging and discharging method of the battery system is executed by the energy storage converter; the forced charging and discharging method of the battery system comprises:

[0031] when the operation information of the battery assembly on the control assembly meets a forced charging and discharging condition, issuing a forced control instruction to the control assembly, and performing a preset action on the battery assembly through the total positive terminal and the total negative terminal;

[0032] wherein, when the forced charging and discharging condition is a forced charging condition, the forced control instruction is a forced charging instruction, and the preset action is charging; when the forced charging and discharging condition is a forced discharging condition, the forced control instruction is a forced discharging instruction, and the preset action is discharging.

[0033] Optionally, after issuing the forced control instruction to the control assembly and performing the preset action on the battery assembly through the total positive terminal and the total negative terminal, the forced charging and discharging method further comprises:

[0034] when the operation information of the battery assembly on the control assembly meets a forced control stop condition corresponding to the currently performed preset action, issuing a forced control end instruction to the control assembly, and stopping the preset action;

[0035] wherein, when the currently performed preset action is charging, the forced control stop condition is a forced charging end condition, and the forced control end instruction is a forced charging end instruction; when the currently performed preset action is discharging, the forced charging and discharging stop condition is a forced discharging end condition, and the forced control end instruction is a forced discharging end instruction.

[0036] Optionally, the energy storage converter is further connected to a power grid;

[0037] when the preset action is charging, the energy storage converter takes the power grid as a power supply of the battery assembly; when the preset action is discharging, the energy storage converter takes the power grid as a load of the battery assembly.

[0038] In a third aspect, the embodiments of the present application further provide a battery system, comprising: a battery assembly, a switch assembly, a control assembly and an energy storage converter; the battery assembly and the switch assembly are connected in series between a total positive terminal and a total negative terminal of the battery system, the control assembly is connected to the battery assembly, the switch assembly and the energy storage converter respectively; and the energy storage converter is further connected to the total positive terminal and the total negative terminal respectively.

[0039] The control assembly is configured to execute the forced charging and discharging method of the battery system according to any of the embodiments of the present application, and the energy storage converter is configured to execute the forced charging and discharging method of the battery system according to any of the embodiments of the present application.

[0040] In the forced charging and discharging method of the battery system according to the embodiments of the present application, the control assembly determines whether to start the forced charging and discharging operation based on the received forced control instruction and the actual voltage fault alarm level, which is equivalent to preliminarily identifying the correctness of the forced control instruction and can avoid misoperation to a certain extent. Moreover, when forced charging and discharging is needed, the battery assembly does not need to be disassembled and externally connected to a charger or a load, but the switch assembly is forced to be turned on, and the original charging and discharging circuit of the battery system is used for charging and discharging. In this way, firstly, the forced charging and discharging can be realized based on the original hardware conditions, without the need to adjust the wiring, saving manpower and time, improving the charging and discharging efficiency, reducing the disassembly and assembly loss and risk; secondly, the original charging and discharging circuit is used to directly force the entire battery assembly to charge and discharge, without the need to disassemble the battery assembly into multiple parts for separate charging and discharging, which can avoid the problem of uneven charging and discharging and ensure the system reliability and safety; thirdly, there is no need to purchase or independently develop the equipment required for forced charging and discharging, which can effectively reduce the cost, and the code modification is flexible, with strong portability, without damaging the existing function modules of the control assembly and affecting other fault detection and protection functions of the system. In summary, the embodiments of the present application can improve the efficiency of forced charging and discharging of the battery system and reduce the cost on the basis of ensuring the reliability of the battery system.

[0041] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creating laborious work.

[0043] Figure 1 is a structural schematic diagram of a battery system provided by the embodiments of the present application;

[0044] Figure 2 is a flowchart of a forced charging and discharging method of a battery system according to an embodiment of the present application;

[0045] Figure 3 is a flowchart of another forced charging and discharging method of a battery system according to an embodiment of the present application;

[0046] Figure 4 is a flowchart of a method for determining whether a preset action actually occurs according to an embodiment of the present application;

[0047] Figure 5 is a flowchart of another forced charging and discharging method of a battery system according to an embodiment of the present application;

[0048] Figure 6 is a flowchart of another forced charging and discharging method of a battery system according to an embodiment of the present application;

[0049] Figure 7 is a flowchart of another forced charging and discharging method of a battery system according to an embodiment of the present application;

[0050] Figure 8 is a flowchart of another forced charging and discharging method of a battery system according to an embodiment of the present application;

[0051] Figure 9 is a schematic structural diagram of another battery system according to an embodiment of the present application. DETAILED DESCRIPTION

[0052] In order to make the personnel in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0053] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion.

[0054] As mentioned in the background, after triggering the protection to cut off the charge-discharge circuit of the battery system, the battery pack needs to be disassembled for charging and discharging. The main disadvantages of this solution include:

[0055] 1. Time-consuming and laborious actual operation process. In large cabinets, multiple battery packs are often connected in series, and the number of circuit boards and battery packs that need to be disassembled is large. During the reassembly process, re-wiring may be involved, which can increase the risk of the system and affect the reliability of the system.

[0056] 2. Increased external purchase cost / development cost. Whether purchasing or independently developing a charger requires time and money costs, and new external equipment also has problems such as maintenance and after-sales.

[0057] 3. Low charging efficiency of external chargers. Especially for cabinets with multiple battery packs, when the system as a whole is under-voltage or over-voltage, the number of battery packs that need to be charged and discharged is large, and the disassembly and charging and discharging process is complicated. Without the aid of the system platform for charging and discharging, it is easy to cause uneven charging voltage, affecting the reliability and life of the system.

[0058] 4. Large area over-voltage and under-voltage of the battery is not a common phenomenon. This situation mostly occurs when the battery pack is left for a long time or used improperly. Purchasing related charging and discharging equipment or investing in development plans for this purpose will cause waste of resources.

[0059] In summary, in the related art, the charging and discharging efficiency of the battery pack after disassembly is low, the cost is high, and the system reliability is affected.

[0060] To solve the above problems, the embodiments of the present application provide a forced charging and discharging method for a battery system. The original charging and discharging circuit of the battery system is used for forced charging and discharging after under-voltage / over-voltage, which can improve the efficiency of forced charging and discharging of the battery system and reduce the cost on the basis of ensuring the reliability of the battery system. To facilitate the explanation of the method, the basic structure of the battery system will be briefly described first.

[0061] Figure 1 is a structural schematic diagram of a battery system provided by the embodiments of the present application. Referring to Figure 1 , for example, the battery system can include a battery assembly 10, a switch assembly 20, a control assembly 30, and a power conversion system (PCS) 40. The battery assembly 10 and the switch assembly 20 are connected in series between the total positive end P1 and the total negative end P2 of the battery system, the control assembly 30 is connected to the battery assembly 10, the switch assembly 20, and the power conversion system 40 respectively, and the power conversion system 40 is also connected to the total positive end P1 and the total negative end P2 respectively.

[0062] Specifically, the battery assembly 10 can include a plurality of battery packs connected in series between the positive electrode BAT1 and the negative electrode BAT2 of the battery assembly 10, and each battery pack can include a plurality of battery cells connected in series. The switch assembly 20 can include: a first switch unit 210 connected between the positive electrode BAT1 of the battery assembly 10 and the total positive end P1, and a second switch unit 220 connected between the negative electrode BAT2 of the battery assembly 10 and the total negative end P2. The first switch unit 210, the battery assembly 10 and the second switch unit 220 are connected in series between the total positive end P1 and the total negative end P2 in turn, forming a charging and discharging circuit (or high-voltage circuit) of the battery assembly 10, and the on-off of the switch assembly 20 determines the on-off of the charging and discharging circuit. When at least one switch unit in the switch assembly 20 is turned off, the switch assembly 20 is turned off; when both switch units are turned on, the switch assembly 20 is turned on. Exemplarily, the first switch unit 210 and the second switch unit 220 can be synchronously turned on or turned off.

[0063] The control assembly 30 can collect the operating parameters of the battery assembly 10 in real time, such as the current, voltage and temperature of each battery cell, and the total voltage and electrode temperature of the battery assembly 10, and can control the operating state of the battery assembly 10, such as charging and discharging balancing. The control part of the energy storage converter 40 can be connected to the control assembly 30 and exchange data with the control assembly 30, such as receiving the operating information uploaded by the control assembly 30 and issuing control instructions to the control assembly 30. The energy conversion part of the energy storage converter 40 can be connected to the total positive end P1 and the total negative end P2, and to the power grid. The control part of the energy storage converter 40 can control the working state of the energy conversion part thereof. When the switch assembly 20 is turned on, based on the control of the energy storage converter 40, the power grid can be used as a power supply to charge the battery assembly 10, or as a load to discharge the battery assembly 10 to the power grid.

[0064] The implementation of the forced charging and discharging method of the battery system will be described below based on the control assembly 30 and the energy storage converter 40 respectively.

[0065] The embodiment of the present application provides a forced charging and discharging method of a battery system, which is executed by a control assembly, and the forced charging and discharging method of the battery system comprises: when a forced control instruction issued by an energy storage converter is received, and the alarm level of a voltage fault in the battery assembly is within a preset alarm level range, closing a fault protection operation corresponding to the voltage fault in the preset alarm level range, and starting a forced charging and discharging operation.

[0066] The fault protection operation corresponding to the voltage fault in the preset alarm level range includes: controlling the switch assembly to be turned off. The forced charging and discharging operation includes: controlling the switch assembly to be turned on, so that the energy storage converter can perform a preset action on the battery assembly through the total positive terminal and the total negative terminal. When the forced control instruction is a forced charging instruction, the voltage fault is an under-voltage fault, and the preset action is charging; when the forced control instruction is a forced discharging instruction, the voltage fault is an over-voltage fault, and the preset action is discharging.

[0067] Specifically, voltage stabilization / balancing is an important indicator for the safe operation of a battery system. When a voltage fault occurs in a battery assembly, both excessively high and excessively low voltage can increase the internal pressure of the battery assembly, affect the charging and discharging efficiency of the battery assembly, accelerate the aging process of the battery assembly, shorten the service life of the battery assembly, and easily cause safety problems such as short circuit, liquid leakage, and thermal runaway. Therefore, during the operation of the battery system, the control assembly detects the voltage and SOC (State Of Charge, remaining capacity) of the battery assembly in real time and uploads the information to the energy storage converter in real time. It can be understood that the operation of the system can be in actual use and in the test process, and the specific scenarios are not limited here.

[0068] Generally, in the control assembly, a plurality of alarm protection levels are provided according to the severity of the voltage fault, a series of alarm levels are set, and corresponding fault protection operations under each alarm level are specified. Among them, the fault protection operation corresponding to the voltage fault under at least part of the alarm levels includes turning off the switch assembly. For example, when the fault is less severe, such as slight overvoltage / under-voltage, the fault protection operation can be only to alarm without turning off the switch assembly, such as alarming by sound, light, vibration, etc. to prompt relevant personnel to pay attention to the voltage condition; when the fault is more severe, i.e. the actual voltage deviates from the voltage allowed range more due to overvoltage / under-voltage, the fault protection operation can be to alarm and turn off the switch assembly at the same time, stopping the charging and discharging of the battery assembly to avoid further expansion of the fault. Then, the preset alarm level range includes at least part of the voltage fault alarm levels whose fault protection operation includes turning off the switch assembly. Turning off the switch assembly can be turning off at least one of the first switch unit and the second switch unit. It can be understood that the first switch unit and the second switch unit can each include one or more of a relay, a circuit breaker, and a contactor; the specific operation of turning off the switch assembly can be different under different alarm levels of the voltage fault, such as different types of switch devices and / or different sequences of turning off the switch devices, which are not limited here. The control assembly can store the judgment conditions of the voltage fault under each level and the corresponding fault protection operation in the control assembly. The control assembly can determine whether a voltage fault occurs in the battery assembly according to the voltage condition of the battery assembly, and determine the alarm level of the voltage fault when a voltage fault occurs.

[0069] The energy storage converter determines whether the battery assembly needs to be forced to charge and discharge according to the operation information of the battery assembly, and issues a forced control instruction to the control assembly when forced charging and discharging is needed. For example, a forced charging instruction is issued when the total voltage / cell voltage / SOC of the battery assembly is lower than the corresponding preset limit value, and a forced discharging instruction is issued when the total voltage / cell voltage / SOC of the battery assembly is higher than the corresponding preset limit value.

[0070] Referring to Figure 2 The forced charging and discharging method of the battery system can specifically include the following steps:

[0071] S110, determine whether a forced control instruction issued by the energy storage converter is received; if yes, execute S120, and if no, end the current control.

[0072] In the case where the energy storage converter does not issue a forced control instruction, the control assembly can perform corresponding fault protection operations according to the voltage fault alarm level determined by monitoring, for example, the switch assembly is controlled to be disconnected when the alarm level of the voltage fault is within the preset alarm level range.

[0073] It can be understood that the "end" in each figure of the embodiments of the present application refers to the end of the current forced charging and discharging control process. Since the control assembly is real-time monitoring the operation information of the battery assembly and uploading to the energy storage converter, and the energy storage converter is also real-time determining whether forced charging and discharging is needed, after each forced charging and discharging control process ends, the next forced charging and discharging control process can be entered. The execution frequency of the forced charging and discharging control process can be set according to actual needs, which is not limited here.

[0074] S120, determine whether the alarm level of the voltage fault in the battery assembly is within the preset alarm level range; if yes, execute S130; if no, end the current control.

[0075] In the case where the energy storage converter has issued a forced control instruction, the determination of this step S120 is equivalent to further determining whether there is a need for forced charging and discharging according to the actual voltage condition of the battery assembly. When the forced control instruction is issued by the energy storage converter and the alarm level of the corresponding voltage fault in the battery assembly is within the preset alarm level range, the forced charging and discharging operation corresponding to the operation is executed again, which can effectively avoid misoperation.

[0076] S130, close the fault protection operation corresponding to the voltage fault within the preset alarm level range, and start the forced charging and discharging operation.

[0077] Specifically, the fault protection operation corresponding to the voltage fault in the preset alarm level range is closed, which is equivalent to shielding the fault protection operation corresponding to each alarm level voltage fault in the preset alarm level range, thereby avoiding the control component from disconnecting the switch component in response to the demand of the fault protection operation during the forced charging / discharging process. Then, the forced charging / discharging operation is started, which is equivalent to forcibly controlling the switch component to be turned on, and the existing charging / discharging circuit in the battery system is used to forcibly charge / discharge the battery component through the energy storage converter. Specifically, the battery component needs to be forcibly charged under the condition of an under-voltage fault, and the battery component needs to be forcibly discharged under the condition of an over-voltage fault.

[0078] The forced charging / discharging method of the battery system provided by the embodiment of the application can preliminarily identify the correctness of the forced control instruction based on the received forced control instruction and the actual voltage fault alarm level, which can avoid misoperation to a certain extent. When forced charging / discharging is needed, the battery component does not need to be disassembled and externally connected to a charger or a load, but the switch component is forcibly controlled to be turned on, and the existing charging / discharging circuit of the battery system is used for charging / discharging. In this way, the forced charging / discharging can be realized based on the original hardware conditions, without the need to adjust the wiring, saving manpower and time, improving the charging / discharging efficiency, reducing disassembly and assembly loss and risk, directly using the original charging / discharging circuit to forcibly charge / discharge the entire battery component without the need to disassemble the battery component for separate charging / discharging, avoiding the problem of unbalanced charging / discharging, ensuring system reliability and safety, without the need to purchase or independently develop equipment required for forced charging / discharging, effectively reducing the cost, and the code modification is flexible, has strong portability, does not damage the existing functional modules of the control component, and does not affect other fault detection and protection functions of the system. In summary, the embodiment of the application can improve the efficiency of forced charging / discharging of the battery system and reduce the cost on the basis of ensuring the reliability of the battery system.

[0079] On the basis of the above-mentioned embodiments, the battery component can include a plurality of battery cells connected in series between the positive electrode and the negative electrode of the battery component, and the plurality of battery cells can belong to one or more battery packs. Specifically, the under-voltage fault in the voltage fault can include a single battery cell under-voltage fault and a total voltage under-voltage fault of the battery component. The over-voltage fault in the voltage fault can include a single battery cell over-voltage fault and a total voltage over-voltage fault of the battery component.

[0080] The cell voltage is the voltage between the two ends of a single cell. Overly high or low cell voltage can cause a large voltage difference between the cells in the battery pack, affecting the charging and discharging efficiency of the battery pack, resulting in incomplete charging or discharging, and thus affecting the endurance of the battery pack. The total voltage of the battery assembly is the voltage between the positive and negative electrodes of the battery assembly. Overvoltage can easily cause internal overheating and electrolyte rupture of the battery assembly, and under-voltage can easily cause a significant reduction in battery capacity, affecting the normal operation of the system. Therefore, whether it is an under-voltage or over-voltage fault, the cell voltage and the total voltage of the battery assembly are considered. As long as the alarm level of one of the faults is within the corresponding preset alarm level range, it is considered that there is a charging / discharging requirement.

[0081] On the basis of the above-mentioned embodiments, the alarm level of the voltage fault in the battery assembly includes at least three alarm levels. The number of alarm levels is positively correlated with the severity of the voltage fault, that is, the higher the alarm level, the farther the voltage deviates from the normal range, and the more serious the fault. For under-voltage faults, the control logic is that the alarm voltage threshold decreases from the first level to the last level, and the corresponding fault protection operation is gradually enhanced, for example, the switching assembly is cut off faster and / or the switching assembly is cut off more and more. Taking the cell under-voltage fault as an example, the lowest voltage among all cell voltages is compared with the alarm voltage threshold of each alarm level to determine the alarm level of the current voltage fault. For over-voltage faults, the control logic is that the alarm voltage threshold increases from the first level to the last level, and the corresponding fault protection operation is gradually enhanced. It can be understood that the fault protection operation intensity of the single cell under-voltage fault, the total voltage under-voltage fault of the battery assembly, the single cell over-voltage fault, and the total voltage over-voltage fault of the battery assembly is the same at the same level.

[0082] Exemplarily, the preset alarm level range includes alarm levels other than the first and last alarm levels. The first alarm level is the first alarm level, and the fault of this level is slight. The fault protection operation can be set to only alarm but not to keep the switching assembly closed, so there is no need to shield the fault protection operation of this alarm level during forced charging and discharging. When the system appears the second and subsequent alarms, the fault protection operation can be set to disconnect the switching assembly to achieve the purpose of being unable to charge and discharge the battery assembly through the high-voltage loop, and to achieve fault protection. The last alarm level is the last alarm level. The fault at this level is serious, and the risk of switching on the switching assembly again is too great, so the switching assembly is not allowed to be switched on again. Therefore, the preset alarm level range provided in this embodiment comprehensively considers the specific fault protection operation at each alarm level and the risk of shutting down the fault protection operation at each alarm level, so that the forced charging and discharging strategy is more scientific and reliable. Exemplarily, the alarm level of the voltage fault is four levels in total, and the preset alarm level range includes the second and third alarm levels.

[0083] It should be noted that in the forced charging and discharging process of the embodiment of the application, only the fault protection operation corresponding to the voltage fault in the preset alarm level range is closed (or shielded), and the fault protection operation under other fault voltage alarm levels and other fault types is not closed. For example, if the fault type such as overcurrent or overtemperature that needs to control the switch assembly to be disconnected occurs in the forced charging and discharging process, the control assembly can still perform the fault protection operation corresponding to the fault type, and normally control the switch assembly to be disconnected to ensure the safety of the system.

[0084] Figure 3 is a flowchart of another forced charging and discharging method of a battery system provided by the embodiment of the application. Referring to Figure 3 , the forced charging and discharging method of the battery system specifically includes the following steps:

[0085] S210, it is judged whether the forced control instruction issued by the energy storage converter is received; if yes, S220 is executed; if no, the control is ended.

[0086] S220, it is judged whether the alarm level of the voltage fault in the battery assembly is in the preset alarm level range; if yes, S230 is executed; if no, the control is ended.

[0087] Among them, if there is no voltage fault in the preset alarm level range, the following situations can occur:

[0088] 1) There is no voltage fault alarm or the alarm level is lower than the lower limit level of the preset alarm level range, which indicates that the forced control instruction sent by the energy storage converter is incorrect, and at this time, the instruction can be ignored to control the system to normally operate. Among them, the reasons for the incorrect forced control instruction are: 1, to prevent over-discharge of the battery system, when the SOC is lower than 2%, the energy storage converter will immediately issue a forced charging instruction, but at this time, there is no under-voltage fault in the system, or the alarm level of the under-voltage fault does not reach the corresponding preset alarm level range; 2, communication errors can cause the forced control instruction to be sent incorrectly.

[0089] 2) The alarm level of the voltage fault is higher than the upper limit level of the preset alarm level range, which indicates that the voltage fault is relatively serious, and the switch assembly is not allowed to be controlled to be turned on, and the forced charging and discharging through the original charging and discharging circuit is not supported, and fault maintenance needs to be performed in time.

[0090] S230, the fault protection operation corresponding to the voltage fault in the preset alarm level range is closed, and the forced charging and discharging operation is started.

[0091] S240, the action duration corresponding to the preset action is counted.

[0092] The step is performed after starting the forced charging and discharging operation. When the preset action is charging, the charging duration is counted, and when the preset action is discharging, the discharging duration is counted.

[0093] S250, determine whether the action duration exceeds the preset duration; if yes, perform S270; if no, perform S260.

[0094] The preset duration can be set according to the performance of the battery assembly, for example, can be set according to actual calculation or according to empirical value. The preset duration is, for example, a preset charging / discharging duration for charging / discharging the battery assembly from an under-voltage / over-voltage state to a normal voltage range. The preset charging duration and the preset discharging duration can be the same or different. For example, the preset charging duration and the preset discharging duration are the same preset duration, for example, 5 minutes.

[0095] S260, continue to perform the forced charging and discharging operation.

[0096] When the action duration does not exceed the preset duration, the fault protection operation corresponding to the voltage fault in the preset alarm level range can be continued to be closed, and the forced charging and discharging operation is performed to continue to charge / discharge the battery assembly.

[0097] S270, determine whether the preset action actually occurs according to the electrical parameters of the battery assembly; if yes, perform S280; if no, perform S290.

[0098] When the action duration exceeds the preset duration, according to the expected charging and discharging progress, the charging and discharging of the battery assembly can be successfully completed. At this time, whether the preset action actually occurs can be determined according to the current electrical parameters of the battery assembly, such as voltage or current, and then it can be confirmed whether the forced control instruction is an instruction sent by mistake by the energy storage converter, so as to confirm the subsequent processing flow.

[0099] S280, start the fault protection operation corresponding to the voltage fault in the preset alarm level range, and wait to receive the forced control end instruction corresponding to the forced control instruction issued by the energy storage converter.

[0100] When the preset action has occurred, the energy storage converter further determines whether the preset action is completed according to the operating parameter of the battery assembly uploaded by the control assembly, and issues a corresponding forced control end instruction to the control assembly as an end identifier of the current forced charging and discharging when the preset action is completed. When the control assembly determines that the preset action has occurred, the control assembly can first start the fault protection operation corresponding to the voltage fault in the preset alarm level range, which is equivalent to canceling the shielding of the fault protection operation corresponding to the voltage fault in the preset alarm level range, returning to the normal voltage fault protection, and then waiting for the forced control end instruction to complete the current forced charging and discharging control. The end identifier corresponding to the forced charging instruction is a forced charging end instruction, and the end identifier corresponding to the forced discharging instruction is a forced discharging end instruction.

[0101] S290, starting the fault protection operation corresponding to the voltage fault in the preset alarm level range, and waiting to receive the next forced control instruction issued by the energy storage converter.

[0102] When the preset action has not occurred, the energy storage converter does not actually perform the forced charging and discharging related operation, and therefore, there is no forced control end instruction as the end identifier of the current forced charging and discharging. In this case, the control assembly directly resumes starting the fault protection operation corresponding to the voltage fault in the preset alarm level range, which is equivalent to completing the current forced charging and discharging control, and can enter a state of waiting to receive the next forced control instruction, that is, can enter S210 in the next charging and discharging control process.

[0103] The embodiment of the application provides a forced charging and discharging method of a battery system through S210-S290. After starting the forced charging and discharging operation, whether the preset action occurs is determined according to the electrical parameter of the battery assembly after a preset time period, which mainly discriminates the case that the forced control instruction is issued but the energy storage converter does not actually charge and discharge the battery assembly. At the same time, the effect of the forced charging and discharging can be determined, so as to timely resume the original voltage fault protection and enter the next forced charging and discharging control, avoiding the strategy staying in the state of the forced control switch assembly being turned on, so that the switch assembly is turned off in time through the original voltage fault protection strategy in the case of actual non-forced charging / forced discharging, ensuring the safety of the system, for example, avoiding irreversible loss caused by self-consumption in the under-voltage mode. For example, the control assembly can continuously acquire the forced control instruction during the timing period, and the energy storage converter can broadcast the forced control instruction every 100 ms.

[0104] On the basis of the above-mentioned embodiments, optionally, the battery assembly includes a plurality of battery cells connected in series between the positive electrode and the negative electrode of the battery assembly, and the electrical parameter of the battery assembly includes: the maximum voltage in the single battery voltage of each battery cell, and the action current flowing through the battery assembly. Then, S270 specifically includes:

[0105] When the extreme value voltage meets the voltage preset condition, and / or, the action current meets the current preset condition, it is determined that the preset action has actually occurred.

[0106] That is, when at least one of the voltage preset condition and the current preset condition is met, it can be considered that the preset action has actually occurred, and the instruction issued by the energy storage converter is consistent with the executed action. It can be understood that the two judgment conditions belong to a parallel relationship, and as long as any one of them is met, it can be determined that the system has entered the state of forced charging / discharging, and only the forced control end instruction corresponding to the forced control instruction is needed to determine that the forced charging / discharging has been completed. When it is determined that the preset action has occurred, the original fault protection operation is restored, and the purpose of protecting the battery system can be achieved.

[0107] When the extreme value voltage does not meet the voltage preset condition, and the action current does not meet the current preset condition, it is determined that the preset action has not actually occurred.

[0108] That is, when neither the voltage preset condition nor the current preset condition is met, it can be considered that the preset action has not actually occurred, and the instruction issued by the energy storage converter is inconsistent with the executed action.

[0109] When the forced control instruction is a forced charging instruction, the extreme value voltage is the lowest voltage among the single voltages of the battery cells, and the action current is the charging current; the voltage preset condition is that the lowest voltage is greater than a first voltage threshold; and the current preset condition is that the charging current is greater than a first current value and the duration of the charging current is greater than a first preset time. The first voltage threshold can be determined according to the actual working characteristics of the battery cells, for example, it can be set to a smaller value within the normal working voltage range, which can be 3.2V. The first current value and the first preset time can be determined according to the actual working characteristics of the battery assembly, for example, the first current value is 1A and the first preset time is 5s.

[0110] When the forced control instruction is a forced discharge instruction, the extreme value voltage is the highest voltage among the single voltages of the battery cells, and the action current is the discharge current; the voltage preset condition is that the highest voltage is less than a second voltage threshold; and the current preset condition is that the discharge current is greater than a second current value and the duration of the discharge current is greater than a second preset time; wherein the second voltage threshold is greater than the first voltage threshold. The second voltage threshold can be determined according to the actual working characteristics of the battery cells, for example, it can be set to a larger value within the normal working voltage range, which can be 3.45V. The second current value and the second preset time can be determined according to the actual working characteristics of the battery assembly, the first current value and the second current value can be the same or different, and the first preset time and the second preset time can be the same or different; for example, the second current value is 1A and the second preset time is 5s.

[0111] Figure 4is a flowchart of a process for determining whether a preset action actually occurs, provided by an embodiment of the present application. Referring to Figure 4 In one specific embodiment, the specific steps of S270 can optionally include:

[0112] S310, obtaining the maximum voltage and the action current.

[0113] S320, determining whether the maximum voltage meets the voltage preset condition; if yes, performing S330; if no, performing S340.

[0114] S330, determining that the preset action has actually occurred.

[0115] S340, determining whether the action current meets the current preset condition; if yes, performing S330; if no, performing S350.

[0116] S350, determining that the preset action has not actually occurred.

[0117] This embodiment provides a specific determination process for whether a preset action actually occurs through S310-S350, but is not a limitation on the present application. In other embodiments, the order of S320 and S340 can also be adjusted, for example, the determination of S340 is performed first, and then the determination of S320 is performed, or the determinations of S320 and S340 can be performed simultaneously.

[0118] On the basis of the above-mentioned embodiments, before starting the forced charging and discharging operation, the method can further include: determining whether a forced control end instruction corresponding to the forced control instruction issued by the energy storage converter is received; if yes, stopping the forced charging and discharging operation, and starting the fault protection operation corresponding to the voltage fault in the preset alarm level range; if no, starting the forced charging and discharging operation, and counting the action duration corresponding to the preset action. Correspondingly, when the action duration does not exceed the preset duration, returning to the step of determining whether the forced control end instruction corresponding to the forced control instruction issued by the energy storage converter is received.

[0119] In this embodiment, the energy storage converter is determined in real time whether the forced control end instruction is issued during the timing process. The energy storage converter also determines in real time whether the preset action is completed during the execution of the preset action. In actual application, it is very likely that the charging and discharging is completed in advance. This embodiment adds the determination of whether the forced control end instruction is received, which is beneficial to jumping out of the loop, stopping the forced charging and discharging, and starting the original overvoltage fault protection when the preset action is completed, thereby avoiding new overvoltage / undervoltage problems caused by forced charging and discharging, and ensuring the reliability of the system forced charging and discharging.

[0120] Specifically, referring to Figure 5 The forced charging and discharging method of the battery system includes the following steps:

[0121] S401, determining whether a forced control instruction issued by the energy storage converter is received; if yes, performing S402; if no, ending the current control.

[0122] S402, determining whether an alarm level of a voltage fault in the battery assembly is within a preset alarm level range; if yes, performing S403; if no, ending the current control.

[0123] S403, closing a fault protection operation corresponding to the voltage fault within the preset alarm level range.

[0124] The step can be considered as a forced charging and discharging preparation step.

[0125] S404, determining whether a forced control end instruction is received; if yes, performing S405; if no, performing S406.

[0126] S405, stopping the forced charging and discharging operation, and starting the fault protection operation corresponding to the voltage fault within the preset alarm level range.

[0127] S406, starting the forced charging and discharging operation.

[0128] S407, counting an action duration corresponding to a preset action.

[0129] S408, determining whether the action duration exceeds a preset duration; if yes, performing S409; if no, returning to perform S404.

[0130] S409, obtaining a maximum voltage and an action current.

[0131] S410, determining whether at least one of the following conditions is met: the maximum voltage meets a voltage preset condition, and the action current meets a current preset condition; if yes, performing S411; if no, performing S412.

[0132] S411, starting the fault protection operation corresponding to the voltage fault within the preset alarm level range, and waiting for a forced control end instruction corresponding to a forced control instruction issued by the energy storage converter.

[0133] S412, starting the fault protection operation corresponding to the voltage fault within the preset alarm level range, and waiting for a forced control instruction issued by the energy storage converter next time.

[0134] The embodiment provides specific steps of the forced charging and discharging method of the battery system through S401-S412, and the forced charging and discharging of the system in a voltage fault state can be safely and reliably realized, which is beneficial to maintaining system stability.

[0135] The control strategy of forced charging and discharging is exemplarily given in each of the above embodiments. Taking the preset alarm level range including two alarm levels of level two and level three as an example, the specific control processes of forced charging and forced discharging are described respectively.

[0136] Figure 6 is a flowchart of another forced charging and discharging method of a battery system provided by an embodiment of the application. Referring to Figure 6 In an embodiment, the specific process of forced charging control includes the following steps.

[0137] S501, determining whether a forced charging instruction is received; if yes, performing S502; if no, ending the current control.

[0138] S502, determining whether there is an under-voltage fault of an alarm level of level one or above and level four or below; if yes, performing S503; if no, ending the current control.

[0139] S503, closing the fault protection operation corresponding to the under-voltage fault under the alarm levels of level two and level three.

[0140] S504, determining whether a forced charging end instruction is received; if yes, performing S505; if no, performing S506.

[0141] S505, ending forced charging and starting the fault protection operation corresponding to the under-voltage fault under the alarm levels of level two and level three.

[0142] The ending of forced charging is to stop the forced charging and discharging operation and restore the normal voltage fault protection related operation.

[0143] S506, performing forced charging and counting the charging duration.

[0144] The performing of forced charging is to start the forced charging and discharging operation and control the switch component to be conductive.

[0145] S507, determining whether the charging duration exceeds a preset duration; if yes, performing S508; if no, returning to perform S504.

[0146] S508, obtaining the lowest voltage and the charging current.

[0147] S509, determining whether at least one of the following conditions is met: the lowest voltage is greater than a first voltage threshold, the charging current is greater than a first current value and the duration is greater than a first preset time; if yes, performing S510; if no, performing S511.

[0148] S510, starting the fault protection operation corresponding to the under-voltage fault under the alarm levels of level two and level three and waiting for a forced charging end instruction.

[0149] S511, start the fault protection operation corresponding to the undervoltage fault under the secondary and tertiary alarm levels, and wait for the next forced charging instruction.

[0150] The embodiment provides the specific process of the forced charging control through S501-S511.

[0151] Figure 7 is a flowchart of another forced charging and discharging method of the battery system provided by the embodiment of the application. Referring to Figure 7 In another embodiment, the specific process of the forced discharging control comprises the following steps:

[0152] S601, determining whether a forced discharging instruction is received; if yes, performing S602; if no, ending the current control.

[0153] S602, determining whether there is an overvoltage fault of an alarm level of one or more and four or less; if yes, performing S603; if no, ending the current control.

[0154] S603, closing the fault protection operation corresponding to the overvoltage fault under the secondary and tertiary alarm levels.

[0155] S604, determining whether a forced discharging end instruction is received; if yes, performing S605; if no, performing S606.

[0156] S605, ending the forced discharging, and starting the fault protection operation corresponding to the overvoltage fault under the secondary and tertiary alarm levels.

[0157] The ending of the forced discharging is to stop the forced charging and discharging operation and restore the normal voltage fault protection related operation.

[0158] S606, performing the forced discharging, and counting the discharging duration.

[0159] The performing of the forced discharging is to start the forced charging and discharging operation and control the switch assembly to be conductive.

[0160] S607, determining whether the discharging duration exceeds a preset duration; if yes, performing S608; if no, returning to perform S604.

[0161] S608, obtaining the maximum voltage and the discharging current.

[0162] S609, determining whether at least one of the following conditions is met: the maximum voltage is less than a second voltage threshold, the discharging current is greater than a second current value and the duration is greater than a second preset time; if yes, performing S610; if no, performing S611.

[0163] S610, start the overvoltage fault corresponding fault protection operation under the secondary and tertiary alarm levels, and wait for the forced discharge end instruction.

[0164] S611, start the overvoltage fault corresponding fault protection operation under the secondary and tertiary alarm levels, and wait for the next forced discharge instruction.

[0165] The embodiment provides a specific flow of forced discharge control through S601-S611.

[0166] The embodiment also provides a forced charging and discharging method of a battery system, applied to an energy storage converter. The forced charging and discharging method of the battery system comprises: when running information of a battery assembly on a control assembly meets a forced charging and discharging condition, issuing a forced control instruction to the control assembly, and performing a preset action on the battery assembly through a total positive end and a total negative end.

[0167] When the forced charging and discharging condition is a forced charging condition, the forced control instruction is a forced charging instruction, and the preset action is charging. When the forced charging and discharging condition is a forced discharging condition, the forced control instruction is a forced discharging instruction, and the preset action is discharging.

[0168] It can be understood that the battery system can still refer to the structure shown in Figure 1 During the running process of the battery system, the control assembly 30 can detect the running information of the battery assembly 10 in real time and upload it to the energy storage converter 40 in real time. The running information of the battery assembly 10 comprises, for example, voltage conditions, current conditions, temperature conditions and SOC of the battery assembly 10, and the voltage conditions can comprise total voltage of the battery assembly 10 and single voltage of each cell in the battery assembly 10. The control assembly 10 can collect and upload the running information of the battery assembly 10 at a certain frequency, which is not limited here.

[0169] The energy storage converter 40 determines whether the battery assembly 10 needs to be forced to charge and discharge according to the running information of the battery assembly 10. When forced charging and discharging is needed, the energy storage converter 40 issues a forced control instruction to the control assembly 30, and at the same time, the energy storage converter 40 controls the energy flow direction to realize charging / discharging of the battery assembly 10.

[0170] Specifically, the energy storage converter can also be connected to the power grid. When the preset action is charging, the energy storage converter takes the power grid as the power supply of the battery assembly and controls the power grid to charge the battery assembly. When the preset action is discharging, the energy storage converter takes the power grid as the load of the battery assembly and controls the battery assembly to discharge to the power grid.

[0171] The battery system forced charging and discharging method provided by the embodiment of the present application includes the following steps.

[0172] Figure 8 is a flowchart of another battery system forced charging and discharging method provided by the embodiment of the present application. Referring to Figure 8 , the battery system forced charging and discharging method includes the following steps.

[0173] S710, when the running information of the battery assembly uploaded to the control assembly meets the forced charging and discharging condition, a forced control instruction is issued to the control assembly, and a preset action is performed on the battery assembly through the total positive end and the total negative end.

[0174] wherein, when the forced charging and discharging condition is a forced charging condition, the forced control instruction is a forced charging instruction, and the preset action is charging; when the forced charging and discharging condition is a forced discharging condition, the forced control instruction is a forced discharging instruction, and the preset action is discharging.

[0175] S720, when the running information of the battery assembly uploaded to the control assembly meets the forced control stop condition corresponding to the currently executed preset action, a forced control end instruction is issued to the control assembly, and the preset action is stopped.

[0176] wherein, when the currently executed preset action is charging, the forced control stop condition is a forced charging end condition, and the forced control end instruction is a forced charging end instruction; when the currently executed preset action is discharging, the forced control stop condition is a forced discharging end condition, and the forced control end instruction is a forced discharging end instruction.

[0177] The embodiment of the present application provides a complete forced charging and discharging control process on the side of the energy storage converter, and the forced charging and discharging can be realized safely and reliably based on the original structure and connection relationship of the battery system.

[0178] The embodiment of the present application also provides a battery system, which can apply the forced charging and discharging method of the battery system provided by any of the above embodiments and has the corresponding beneficial effects. Figure 1 The battery system can include a battery assembly 10, a switch assembly 20, a control assembly 30 and an energy storage converter 40. The battery assembly 10 and the switch assembly 20 are connected in series between a total positive terminal P1 and a total negative terminal P2 of the battery system, the control assembly 30 is connected to the battery assembly 10, the switch assembly 20 and the energy storage converter 40 respectively, and the energy storage converter 40 is also connected to the total positive terminal P1 and the total negative terminal P2 respectively. The control assembly 30 is used to execute the forced charging and discharging method of the battery system on the side of the control assembly provided by any of the embodiments of the present application, and the energy storage converter 40 is used to execute the forced charging and discharging method of the battery system on the side of the energy storage converter provided by any of the embodiments of the present application.

[0179] Figure 9 is another structural schematic diagram of a battery system provided by the embodiment of the present application. Referring to Figure 9 In a specific embodiment, the battery assembly 10 can include a plurality of battery packs 110 connected in series between a positive electrode BAT1 and a negative electrode BAT2 of the battery assembly 10, the battery pack 110 can include a battery module 111 and a battery management unit BMU, the battery module 111 includes a plurality of battery cells E connected in series, and the battery management unit BMU is used to collect operating parameters such as voltage and temperature of each battery cell E in the battery module 111 and to perform equalization management on the battery module 111.

[0180] The switch assembly 20 can include a first switch unit 210 and a second switch unit 220, the first switch unit 210 is connected between the positive electrode BAT1 of the battery assembly 10 and the total positive terminal P1, and the second switch unit 220 is connected between the negative electrode BAT2 of the battery assembly 10 and the total negative terminal P2.

[0181] The control assembly 30 can include a slave battery management unit SBMU and a master battery management unit MBMU, the slave battery management unit SBMU is connected to the battery management unit BMU in each battery pack 110 and connected to the master battery management unit MBMU, and the master battery management unit MBMU is connected to the energy storage converter 40. Exemplarily, the master battery management unit MBMU communicates with the slave battery management unit SBMU and the energy storage converter 40 through a CAN (Controller Area Network) protocol.

[0182] The energy storage converter 40 is also connected to the power grid 50 to control the power grid 50 as a power source or load of the battery assembly 10 in the forced charging and discharging process.

[0183] The control assembly 30 and each battery management unit BMU can be components of a battery management system (BMS). The battery assembly 10 and at least part of the control assembly 30 can be integrated in a battery cabinet 1000. For example, the battery assembly 10 and the slave battery management units SBMU are integrated in the battery cabinet 1000, the slave battery management units SBMU are control boards in the battery cabinet 1000, the master battery management unit MBMU is a cabinet control board, and the master battery management unit MBMU is connected to the slave battery management units SBMU in each battery cabinet 1000. The same master battery management unit MBMU and the same energy storage converter 40 can be shared by each battery cabinet 1000, and the battery assembly 10 in any battery cabinet 1000 can be forced to charge and discharge by using the forced charging and discharging method of the battery system provided in any of the above embodiments. The battery cabinet 1000 can be a production cabinet or a test cabinet, which is not limited herein.

[0184] It should be understood that the various forms of flow shown above can be reordered, additional steps can be added, or steps can be deleted. For example, the steps described in the present application can be performed in parallel, in sequence, or in a different order, as long as the desired results of the technical solutions of the present application can be achieved, and the present application is not limited herein.

[0185] The above detailed description does not constitute a limitation on the protection scope of the present application. 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 replacements and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method of forcibly charging and discharging a battery system, characterized by, The battery system comprises a battery assembly, a switch assembly, a control assembly and a storage converter; the battery assembly and the switch assembly are connected in series between a total positive terminal and a total negative terminal of the battery system, the control assembly is connected to the battery assembly, the switch assembly and the storage converter respectively; the storage converter is further connected to the total positive terminal and the total negative terminal respectively; a forced charging and discharging method of the battery system is executed by the control assembly; the forced charging and discharging method of the battery system comprises: when receiving the forced control instruction issued by the storage converter, and the alarm level of the voltage fault in the battery assembly is within a preset alarm level range, the fault protection operation corresponding to the voltage fault in the preset alarm level range is turned off, and a forced charging and discharging operation is started; wherein the fault protection operation corresponding to the voltage fault in the preset alarm level range comprises: controlling the switch assembly to be disconnected; the forced charging and discharging operation comprises: controlling the switch assembly to be turned on, so that the storage converter can execute a preset action on the battery assembly through the total positive terminal and the total negative terminal; wherein, when the forced control instruction is a forced charging instruction, the voltage fault is an under-voltage fault, and the preset action is charging; when the forced control instruction is a forced discharging instruction, the voltage fault is an over-voltage fault, and the preset action is discharging; after turning off the fault protection operation corresponding to the voltage fault in the preset alarm level range, and starting the forced charging and discharging operation, further comprising: statistically recording the action duration corresponding to the preset action; when the action duration exceeds a preset duration, judging whether the preset action actually occurs according to the electrical parameters of the battery assembly; when the action duration does not exceed the preset duration, continuing to execute the forced charging and discharging operation; wherein, if the preset action actually occurs, the forced charging and discharging method of the battery system further comprises: starting the fault protection operation corresponding to the voltage fault in the preset alarm level range, and waiting for receiving a forced control end instruction corresponding to the forced control instruction issued by the storage converter; if the preset action does not actually occur, the forced charging and discharging method of the battery system further comprises: starting the fault protection operation corresponding to the voltage fault in the preset alarm level range, and waiting for receiving the forced control instruction issued by the storage converter next time; the battery assembly comprises a plurality of battery cells connected in series between a positive electrode and a negative electrode of the battery assembly, and the electrical parameters of the battery assembly comprise: a maximum voltage in the single-cell voltage of each battery cell, and an action current flowing through the battery assembly.

2. The method of claim 1, wherein, judging whether the preset action actually occurs according to the electrical parameters of the battery assembly comprises: when the maximum voltage meets a voltage preset condition, and / or the action current meets a current preset condition, it is determined that the preset action actually occurs; when the maximum voltage does not meet the voltage preset condition, and the action current does not meet the current preset condition, it is determined that the preset action does not actually occur.

3. The method of claim 2, wherein the battery system is forced to charge and discharge when the battery system is connected to the external device. The forced control instruction is a forced charging instruction, the extreme voltage is the lowest voltage among the single voltages of the battery cells, and the action current is a charging current; the voltage preset condition is that the lowest voltage is greater than a first voltage threshold; and the current preset condition is that the charging current is greater than a first current value and a duration of the charging current is greater than a first preset time. The forced control instruction is a forced discharging instruction, the extreme voltage is the highest voltage among the single voltages of the battery cells, and the action current is a discharging current; the voltage preset condition is that the highest voltage is less than a second voltage threshold; and the current preset condition is that the discharging current is greater than a second current value and a duration of the discharging current is greater than a second preset time; wherein the second voltage threshold is greater than the first voltage threshold.

4. The method according to any one of claims 1 to 3, wherein, Before the forced charging and discharging operation is started, the method further comprises: determining whether a forced control end instruction corresponding to the forced control instruction issued by the energy storage converter is received; if yes, stopping the forced charging and discharging operation and starting a fault protection operation corresponding to a voltage fault in a preset alarm level range; if no, starting the forced charging and discharging operation and counting an action duration corresponding to the preset action; when the action duration does not exceed the preset duration, returning to the step of determining whether the forced control end instruction corresponding to the forced control instruction issued by the energy storage converter is received.

5. The method of claim 1, wherein, The under-voltage fault includes a battery cell single under-voltage fault and a battery assembly total under-voltage fault; The over-voltage fault includes a battery cell single over-voltage fault and a battery assembly total over-voltage fault; and / or, The alarm levels of the voltage faults in the battery assembly include at least three alarm levels; wherein a number of the alarm levels is positively correlated with a severity of the voltage faults; The preset alarm level range includes alarm levels other than the first and last alarm levels.

6. A method of forcibly charging and discharging a battery system, characterized by, A battery system includes a battery assembly, a switch assembly, a control assembly and an energy storage converter; the battery assembly and the switch assembly are connected in series between a total positive terminal and a total negative terminal of the battery system, the control assembly is connected to the battery assembly, the switch assembly and the energy storage converter respectively; the energy storage converter is further connected to the total positive terminal and the total negative terminal respectively; a forced charging and discharging method of the battery system is executed by the energy storage converter; the forced charging and discharging method of the battery system comprises: when running information of the battery assembly on the control assembly meets a forced charging and discharging condition, issuing a forced control instruction to the control assembly and executing a preset action on the battery assembly through the total positive terminal and the total negative terminal; wherein when the forced charging and discharging condition is a forced charging condition, the forced control instruction is a forced charging instruction and the preset action is charging; and when the forced charging and discharging condition is a forced discharging condition, the forced control instruction is a forced discharging instruction and the preset action is discharging; after the forced control instruction is issued to the control assembly and the preset action is executed on the battery assembly through the total positive terminal and the total negative terminal, the method further comprises: When the operation information of the battery assembly on the control assembly meets a forced control stop condition corresponding to a preset action currently executed, a forced control end instruction is issued to the control assembly, and the preset action is stopped; When the preset action is charging, the forced control stop condition is a forced charging end condition, and the forced control end instruction is a forced charging end instruction; when the preset action is discharging, the forced control stop condition is a forced discharging end condition, and the forced control end instruction is a forced discharging end instruction.

7. The method of claim 6, wherein, The energy storage converter is further connected to a power grid; When the preset action is charging, the energy storage converter takes the power grid as a power supply of the battery assembly; when the preset action is discharging, the energy storage converter takes the power grid as a load of the battery assembly.

8. A battery system characterized by, Comprise: a battery assembly, a switch assembly, a control assembly, and an energy storage converter; the battery assembly and the switch assembly are connected in series between a total positive terminal and a total negative terminal of the battery system, the control assembly is connected to the battery assembly, the switch assembly, and the energy storage converter respectively; the energy storage converter is further connected to the total positive terminal and the total negative terminal respectively; The control assembly is used to execute the forced charging and discharging method of the battery system in any one of claims 1-5; the energy storage converter is used to execute the forced charging and discharging method of the battery system in any one of claims 6-7.

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