Electric core level protection circuit

Abstract

The invention belongs to the field of energy storage of a new energy power system, and particularly relates to a cell-level protection circuit, a primary circuit of the cell-level protection circuit is connected with a single battery to form the single battery with the cell-level protection circuit, and the primary circuit and the single battery are connected in series to form a battery module; a primary circuit of the electric core level protection circuit is used for controlling charging and discharging paths of the single batteries; a secondary circuit of the electric core level protection circuit is used for monitoring the voltage, temperature and current state information of each single battery in the battery module in real time and judging the charging and discharging states of the single batteries according to the information; and if the abnormal condition of the single battery is detected, a corresponding control instruction is sent out, so that the control on the charge-discharge path of the single battery is realized. According to the invention, when the single battery is overcharged and overdischarged, the single battery can realize self protection through the electric core level protection circuit, and charging and discharging of the whole battery module are not influenced while protection is carried out.

Description

Technical Field

[0001] The present invention belongs to the field of energy storage of new energy power systems, and in particular relates to a cell-level protection circuit. Background Art

[0002] In the field of new energy, rechargeable single cells are increasingly used, especially lithium iron phosphate single cells, which have the characteristics of high energy density and long cycle, and are widely used in energy storage, electric vehicles, etc. In the application of lithium iron phosphate, safety issues are receiving more and more attention.

[0003] At present, in the application of lithium iron phosphate, multiple single cells are connected in series and parallel to form a battery module unit. The protection of the single cell is also based on the entire battery module, and there is very little protection at the single cell level. When the battery cell in the battery module is overcharged, over-discharged or short-circuited, there are the following disadvantages: First, the entire battery module shares a single cell management system, and the protection response speed is slow; second, the overall characteristics of the battery module are subject to the influence of the single cell, that is, when the single cell is full, the battery module cannot be charged, and when the single cell is empty, the battery module cannot be discharged. That is, the failure of the single cell affects the use of the entire battery module. Summary of the invention

[0004] In order to overcome the problems in the prior art, the present invention proposes a cell-level protection circuit.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] The present invention provides a cell-level protection circuit, comprising a single battery, a primary circuit of the cell-level protection circuit and a secondary circuit of the cell-level protection circuit;

[0007] The primary circuit of the cell-level protection circuit is connected to the single battery to form a single battery with a cell-level protection circuit, and multiple single batteries with cell-level protection circuits are connected in series to form a battery module; wherein the primary circuit of the cell-level protection circuit is used to control the charging and discharging paths of the single battery;

[0008] The secondary circuit of the cell-level protection circuit is used to monitor the voltage, temperature and current status information of each single battery with a cell protection circuit in the battery module in real time, and judge the charging and discharging status of the single battery with the cell protection circuit based on the information; if an abnormal situation is detected in the single battery with the cell protection circuit, a corresponding control instruction is issued to realize the charging and discharging control of the single battery with the cell protection circuit.

[0009] Furthermore, the primary circuit of the cell-level protection circuit includes a positive switch and a short-circuit switch; one end of the positive switch is connected to the positive electrode of the single cell, and the other end is connected to the charging and discharging path, and the short-circuit switch is connected to the negative electrode of the single cell to form a single cell with a cell-level protection circuit, and a plurality of single cells with cell protection circuits are connected in series to form a battery module; wherein the positive switch is used to control the charging and discharging path of the single cell; when the positive switch is disconnected, the short-circuit switch is turned on to form a bypass.

[0010] Furthermore, the positive switch includes a plurality of pair-tube structures, each of which is two metal oxide semiconductor field effect transistors connected in series and face to face; the short-circuit switch includes a plurality of pair-tube structures, each of which is two metal oxide semiconductor field effect transistors connected in series and face to face.

[0011] Furthermore, the secondary circuit of the cell-level protection circuit includes a voltage acquisition circuit, a temperature acquisition circuit, a current acquisition circuit, a drive circuit and a microprocessor; the voltage acquisition circuit, the temperature acquisition circuit, the current acquisition circuit and the drive circuit are all connected to the microprocessor; the drive circuit is respectively connected to the positive switch and the short-circuit switch;

[0012] The voltage acquisition circuit is used to monitor the voltage across the single battery with a cell protection circuit in real time; the current acquisition circuit is used to monitor the current state of the single battery with a cell protection circuit; the temperature acquisition circuit is used to monitor the temperature of the single battery with a cell protection circuit; the drive circuit is used to control the on and off of the positive switch and the short-circuit switch according to the instructions of the microprocessor; the microprocessor processes information from each acquisition circuit, and determines the charge and discharge state of the single battery with the cell protection circuit according to a preset logic, and issues corresponding control instructions.

[0013] Furthermore, it also includes an external communication circuit, which is connected to the microprocessor; the external communication circuit is used to transmit the status information of the battery module.

[0014] Furthermore, when the battery module is in a normal charging state, the voltage acquisition circuit acquires the voltage across each single battery with a cell protection circuit, and feeds back the data to the microprocessor in real time, and the microprocessor monitors the voltage changes of each single battery with a cell protection circuit in real time; if a single battery with a cell protection circuit reaches a critical fully charged state, that is, the voltage reaches a preset maximum charging voltage, the microprocessor disconnects the positive switch in the single battery with the cell protection circuit through the driving circuit, and cuts off the charging path of the single battery with the cell protection circuit; at the same time, the microprocessor turns on the short-circuit switch through the driving circuit to form a bypass.

[0015] Furthermore, when the microprocessor confirms through the current acquisition circuit that the battery module is no longer in a charging state, that is, the charging current is less than a preset charging current threshold, the positive switch in the single battery with the battery cell protection circuit is reopened through the driving circuit, and the short-circuit switch is disconnected to restore the charging path of the single battery with the battery cell protection circuit.

[0016] Furthermore, when the battery module is in a normal discharge state, the microprocessor continuously monitors the voltage and current parameters of each single cell with a battery cell protection circuit; when the power of a single cell with a battery cell protection circuit gradually decreases and is less than a preset discharge current threshold, the microprocessor disconnects the positive switch in the single cell with the battery cell protection circuit through a driving circuit; at the same time, the microprocessor turns on the short-circuit switch through the driving circuit to form a bypass.

[0017] Furthermore, when the battery module completes the discharge task or reaches a predetermined discharge termination condition, the microprocessor controls the discharge process to stop; the microprocessor reconfigures the positive switch and the short-circuit switch in the single battery with the cell protection circuit, that is, re-turns on the positive switch and disconnects the short-circuit switch through the driving circuit.

[0018] Furthermore, when the microprocessor determines that a single cell battery with a cell protection circuit has an overcharge or over-discharge fault, the status information of the single cell battery with a cell protection circuit is fed back to the background management system through the communication circuit; after receiving the status information, the background management system immediately parses and processes the status information.

[0019] Compared with the prior art, the present invention has the following technical effects:

[0020] In the present invention, when the battery module is in a charging state, if the single battery connected in series inside the battery module has been fully charged, the protection circuit of the fully charged single battery actively disconnects the positive switch and closes the short-circuit switch at the same time, so that the single battery is in a bypass and no longer charged; at the same time, the battery module as a whole continues to be in a charging state. When the battery module is in a discharging state, if the single battery connected in series inside the battery module has been discharged, the protection circuit of the discharged battery actively disconnects the positive switch and closes the short-circuit switch at the same time, so that the single battery is in a bypass and no longer discharged; at the same time, the battery module as a whole continues to be in a discharging state. Through the cell-level protection circuit, accurate protection of the single battery inside the battery module is achieved. When a single battery fails or is at the critical point of overcharging or over-discharging, the cell-level protection circuit protects the single battery, and the battery module as a whole is not affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 The installation position of the primary circuit of the cell-level protection circuit of the present invention;

[0023] Figure 2 The relationship between the cell-level protection circuit and the battery module of the present invention;

[0024] Figure 3 A primary circuit of the cell-level protection circuit of the present invention;

[0025] Figure 4 It is a secondary circuit block diagram of the cell-level protection circuit of the present invention;

[0026] Figure 5 The voltage acquisition circuit of the present invention;

[0027] Figure 6 The current collection circuit of the present invention;

[0028] Figure 7 The temperature acquisition circuit of the present invention;

[0029] Figure 8 A driving circuit of the present invention;

[0030] Fig. 9 This is the external communication circuit of the present invention.

[0031] In the accompanying drawings, the component names represented by the reference numerals are listed as follows:

[0032] 1. Single battery; 2. Primary circuit of cell-level protection circuit; 3. Single battery with cell-level protection circuit; 4. Battery module. DETAILED DESCRIPTION

[0033] In order to further explain the technical means and effects taken by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the technical solutions proposed by the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments. The specific features, structures or characteristics in one or more embodiments may be combined in any suitable form. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by technicians in the technical field of the present invention.

[0034] In view of the shortcomings of the traditional single cell 1 protection method, the present invention realizes that when the single cell 1 is overcharged or over-discharged, the single cell 1 can protect itself through its cell-level protection circuit, and at the same time, it does not affect the charging and discharging of the entire battery module 4.

[0035] like Figure 1-Figure 9 As shown, a cell-level protection circuit comprises a single cell 1, a primary circuit 2 of the cell-level protection circuit and a secondary circuit of the cell-level protection circuit; the primary circuit 2 of the cell-level protection circuit is connected to both ends of the single cell 1, the positive and negative electrodes of the primary circuit 2 of the cell-level protection circuit are directly connected to the positive and negative terminals of the single cell 1 and are placed above it to form a single cell 3 with a cell-level protection circuit, the positive and negative electrodes of the circuit in the single cell 3 with the cell-level protection circuit replace the positive and negative terminals of the single cell 1 itself, and the positive and negative electrodes of the circuit become the connection points between the single cell 3 with the cell-level protection circuit and the external circuit, which can also be called the cell-level The positive and negative electrodes of the single battery 3 with the protection circuit at the cell level; a plurality of the single battery 3 with the cell-level protection circuit are connected in series to form a battery module 4; wherein the primary circuit 2 of the cell-level protection circuit is used for the charging and discharging path of the single battery 1; the secondary circuit of the cell-level protection circuit is used for real-time monitoring of the voltage, temperature and current status information of each single battery 3 with the cell-level protection circuit in the battery module 4, and judging the charging and discharging status of the single battery 3 with the cell-level protection circuit according to the information; if an abnormal situation of the single battery 3 with the cell-level protection circuit is detected, a corresponding control instruction is issued to realize the control of the charging and discharging path of the single battery 3 with the cell-level protection circuit.

[0036] In this embodiment, the primary circuit of the cell-level protection circuit includes a positive switch and a short-circuit switch; one end of the positive switch is connected to the positive electrode of the single cell 1, i.e., the positive electrode of the cell, and the other end is connected to the charging and discharging path, and the short-circuit switch is connected to the negative electrode of the single cell 1, i.e., the negative electrode of the cell, to form a single cell 3 with a cell-level protection circuit, and multiple single cells 3 with cell-level protection circuits are connected in series to form a battery module 4.

[0037] The positive switch is connected to the charging and discharging path and is used to control the charging and discharging path of the single cell 1. When the single cell 1 is working normally, the positive switch is in the on state, allowing current to pass, so that the single cell 1 can be charged and discharged normally; when the single cell 1 is in abnormal conditions such as overcharge or over discharge, the positive switch will be quickly disconnected, cutting off the charging and discharging path of the single cell 1 to protect the single cell 1 from damage.

[0038] The short-circuit switch works in conjunction with the positive switch to form a bypass. When the positive switch is disconnected, the short-circuit switch will be turned on immediately to short-circuit the positive and negative electrodes of the single battery 3 with the cell-level protection circuit, so that the current bypasses the single battery 1 to prevent the charging and discharging of the entire battery module from being affected. At the same time, the conduction of the short-circuit switch also ensures that the battery module 4 can remain stable when the positive switch is disconnected, avoiding affecting the entire battery module 4.

[0039] The positive switch is composed of 2*N MOSFETs (metal oxide semiconductor field effect transistors), and the short-circuit switch is composed of 2*N MOSFETs. Since there is a body diode inside the MOSFET, in order to completely cut off the circuit, two MOSFETs are connected in series, and the two MOSFETs in series need to be connected face to face (that is, the source is connected to the source, and the drain is connected to the drain) to be used as a pair of tubes; in order to increase the carrying capacity of the circuit, the positive switch may include 2*N MOSFETs, where N≥1. The short-circuit switch is also composed of two MOSFETs in series, and its design purpose is similar to that of the positive switch, but it focuses more on quickly turning on to form a bypass when the positive switch is disconnected to protect the single cell 1 from damage; the two MOSFETs in series can speed up the response speed of the short-circuit switch, ensuring that when the positive switch is disconnected, the short-circuit switch can be quickly turned on to form a bypass, preventing the entire battery module from voltage drift or damage due to long-term open circuit; when the single cell 1 is overcharged, over-discharged, etc., the charge and discharge path of the single cell 1 can be more reliably cut off, and the single cell 1 is protected by bypass, thereby improving the safety of the single cell 1.

[0040] In this embodiment, the secondary circuit of the cell-level protection circuit includes a voltage acquisition circuit, a temperature acquisition circuit, a current acquisition circuit, a drive circuit, an external communication circuit and a microprocessor; the voltage acquisition circuit, the temperature acquisition circuit, the current acquisition circuit, the drive circuit and the external communication circuit are all connected to the microprocessor; the drive circuit is respectively connected to the two ends of the single battery 3 with the cell-level protection circuit, that is, connected to the positive switch and the short-circuit switch, and the external communication circuit is connected to the background management system; wherein the microprocessor is an MCU.

[0041] Figure 5 It is a voltage collection circuit of a cell-level protection circuit, which is connected to the positive and negative electrodes of the single battery 3 of the cell-level protection circuit, and is used to monitor the voltage across each voltage collection circuit and the single battery 3 of the cell-level protection circuit in real time. Figure 6 It is a current acquisition circuit of the cell-level protection circuit, which is connected to the positive and negative electrodes of the single battery 3 of the cell-level protection circuit. The current acquisition circuit is used to monitor the voltage acquisition circuit and the current state of the single battery 3 of the cell-level protection circuit. Figure 7It is a temperature acquisition circuit of the cell-level protection circuit, and the temperature acquisition circuit is used to monitor the temperature of each single battery 3 of the voltage acquisition circuit and the cell-level protection circuit.

[0042] Figure 8 It is a driving circuit for a cell-level protection circuit, and the driving circuit is used to control the on and off of the positive switch and the short-circuit switch according to the instructions of the microprocessor; the microprocessor, as the core of the entire protection circuit, processes information from each acquisition circuit, and determines the charging and discharging status of the single battery 3 with the cell-level protection circuit according to the preset logic, and issues corresponding control instructions; the external communication circuit is used to transmit the status information of the battery module 4.

[0043] Charging management: When the battery module 4 is in a normal charging state, the voltage acquisition circuit collects the voltage at both ends of each single battery 3 with a cell-level protection circuit, and feeds the data back to the MCU in real time; the MCU will monitor the voltage changes of each single battery 3 with a cell-level protection circuit in real time. During the charging process, if a single battery 3 with a cell-level protection circuit reaches a critical fully charged state, that is, the voltage approaches or reaches the preset maximum charging voltage, the MCU will immediately disconnect the positive switch in the single battery 3 with the cell-level protection circuit through the driving circuit, cut off the charging path of the single battery 3 with the cell-level protection circuit, and prevent the single battery 3 with the cell-level protection circuit from overcharging; at the same time, the MCU will also turn on the short-circuit switch to form a bypass, so that the current does not pass through the single battery 3 with the cell-level protection circuit, but flows to the negative electrode of the circuit through the positive electrode of the primary circuit 2 of the cell-level protection circuit, without affecting the charging and discharging of other single batteries 3 with cell-level protection circuits.

[0044] When the MCU confirms through the current acquisition circuit that the battery module 4 is no longer in the charging state, that is, the charging current has dropped below the preset threshold, the positive switch of the battery cell protection circuit is turned on again through the driving circuit, and the short-circuit switch is turned off, thereby restoring the charging path of the single battery 3 with the battery cell-level protection circuit, so that the battery module 4 can enter the standby state or start discharging.

[0045] Discharge management: When the battery module 4 is in a normal discharge state, the MCU will continuously monitor the voltage, current and other parameters of each single battery 3 with a cell-level protection circuit. When the power of a single battery 3 with a cell-level protection circuit gradually decreases and approaches the critical discharge state, the MCU disconnects the positive switch in the primary circuit 2 of the cell-level protection circuit of the single battery 3 with the cell-level protection circuit through the driving circuit; at the same time, the MCU will turn on the short-circuit switch to form a bypass, allowing other single batteries 3 with cell-level protection circuits to continue discharging or ensure the safety of the entire battery module 4.

[0046] When the battery module 4 completes the discharge task or reaches the predetermined discharge termination condition, the MCU stops the discharge process. Subsequently, the MCU reconfigures the positive switch and the short-circuit switch in the battery cell protection circuit, that is, turns on the positive switch again and turns off the short-circuit switch, so that the battery module 4 returns to the standby state or prepares for the next charge.

[0047] As the core component of the management system of the single battery 3 with cell-level protection circuit, the microprocessor continuously monitors the key parameters such as voltage, current and temperature of the single battery 3 with cell-level protection circuit. If the key parameters exceed the preset safety range, the microprocessor determines whether the single battery 3 with cell-level protection circuit has an overcharge or over-discharge fault. When the microprocessor determines that the single battery 3 with cell-level protection circuit has an overcharge or over-discharge fault, the status information of the single battery 3 with cell-level protection circuit is fed back to the background management system through the communication circuit; after receiving the cell status information, the background management system immediately parses and processes the information. After receiving the cell status information, the background management system will immediately parse and process the information to ensure the safe operation of the battery module 4.

[0048] Combination Figure 1-Figure 9 , introduces the specific working principle of this embodiment:

[0049] When the battery module 4 is charged normally, if a single battery 3 with a cell-level protection circuit connected in series in the battery module 4 is already in a critically fully charged state, the MCU collects the voltage at both ends of the single battery 3 with the cell-level protection circuit in real time through the voltage collection circuit when it is in a critically fully charged state, and the MCU actively disconnects the positive switch of the primary circuit 2 of the cell-level protection circuit by issuing instructions to the drive circuit, and turns on the short-circuit switch at the same time. At this time, the current of the battery module 4 no longer flows through the single battery 3 with the cell-level protection circuit, but flows directly to the negative electrode through the positive electrode of the primary circuit 2 of the cell-level protection circuit.

[0050] If the MCU determines through the current acquisition circuit that the battery module 4 is no longer in a charging state, it will immediately send a command to the drive circuit to actively disconnect the short-circuit switch of the primary circuit 2 of the cell-level protection circuit and turn on the positive switch at the same time. When the battery module 4 is in standby mode, the current is zero. If the battery module 4 starts to discharge, the current flows through the single battery 3 with the cell-level protection circuit, and the battery module 4 is in a normal discharge state, the MCU monitors the voltage of each single battery 3 with the cell-level protection circuit in real time through the voltage acquisition circuit.

[0051] If the MCU detects that the voltage of a single battery 3 with a cell-level protection circuit has reached a critical discharge state, the MCU actively disconnects the positive switch of the primary circuit 2 of the cell-level protection circuit by issuing instructions to the drive circuit, and simultaneously turns on the short-circuit switch; at this time, the current of the battery module 4 no longer flows through the single battery 3 with the cell-level protection circuit, but flows through the positive pole of the primary circuit 2 of the cell-level protection circuit to the negative pole of the circuit.

[0052] When the MCU detects that the battery module 4 is no longer in the discharge state through the current acquisition circuit, it immediately sends a command to the drive circuit to actively disconnect the short-circuit switch of the primary circuit 2 of the cell-level protection circuit and turn on the positive switch at the same time. At this time, the battery module 4 is ready to enter the next charge or standby state. When the battery module 4 starts to charge again, the current flows through the single battery 3 with the cell-level protection circuit, and the battery module 4 enters the normal charging state. The MCU continues to monitor the voltage of each single battery in real time through the voltage acquisition circuit to ensure the safety of the charging process.

[0053] The above-mentioned MCU switches the positive switch and the short-circuit switch of the battery cell protection circuit so that the charging and discharging of the battery module 4 is no longer affected by a single battery cell: first, taking lithium iron phosphate as an example, the voltage of a single battery cell is about 3.3V, and taking the voltage liquid-cooled PACK as an example, the voltage of the battery module 4 is about 80V, and whether a single battery cell is bypassed or not has little effect on the overall voltage change of the battery module 4; second, since the battery module 4 is no longer affected by a single battery cell, the utilization rate of the battery cell is maximized.

[0054] Each battery cell is equipped with independent voltage acquisition circuit, current acquisition circuit, and temperature acquisition circuit. The temperature acquisition circuit collects the temperature of the positive and negative terminals of the battery cell to identify the temperature of the battery cell. When a single battery cell is overcharged or over-discharged, the battery cell protection circuit can respond quickly and transmit the battery cell status to the background management system through the communication circuit in real time, so that the background management system can be informed.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A cell-level protection circuit, characterized in that: Including a single battery, a primary circuit of a cell-level protection circuit and a secondary circuit of a cell-level protection circuit; The primary circuit of the cell-level protection circuit is connected to the single battery to form a single battery with a cell-level protection circuit, and multiple single batteries with cell-level protection circuits are connected in series to form a battery module; wherein the primary circuit of the cell-level protection circuit is used to control the charging and discharging paths of the single battery; The secondary circuit of the cell-level protection circuit is used to monitor the voltage, temperature and current status information of each single battery with a cell protection circuit in the battery module in real time, and judge the charging and discharging status of the single battery with the cell protection circuit based on the information; if an abnormal situation is detected in the single battery with the cell protection circuit, a corresponding control instruction is issued to realize the charging and discharging control of the single battery with the cell protection circuit.

2. A cell-level protection circuit according to claim 1, characterized in that: The primary circuit of the cell-level protection circuit includes a positive switch and a short-circuit switch; one end of the positive switch is connected to the positive electrode of the single cell, and the other end is connected to the charging and discharging path. The short-circuit switch is connected to the negative electrode of the single cell to form a single cell with a cell-level protection circuit. A plurality of single cells with cell protection circuits are connected in series to form a battery module; wherein the positive switch is used to control the charging and discharging path of the single cell; when the positive switch is disconnected, the short-circuit switch is turned on to form a bypass.

3. A cell-level protection circuit according to claim 2, characterized in that: The positive switch includes a plurality of pair-tube structures, each of which is two metal oxide semiconductor field effect transistors connected in series and face to face; the short-circuit switch includes a plurality of pair-tube structures, each of which is two metal oxide semiconductor field effect transistors connected in series and face to face.

4. A cell-level protection circuit according to claim 2, characterized in that: The secondary circuit of the cell-level protection circuit includes a voltage acquisition circuit, a temperature acquisition circuit, a current acquisition circuit, a drive circuit and a microprocessor; the voltage acquisition circuit, the temperature acquisition circuit, the current acquisition circuit and the drive circuit are all connected to the microprocessor; the drive circuit is respectively connected to the positive switch and the short-circuit switch; The voltage acquisition circuit is used to monitor the voltage across the single battery with a cell protection circuit in real time; the current acquisition circuit is used to monitor the current state of the single battery with a cell protection circuit; the temperature acquisition circuit is used to monitor the temperature of the single battery with a cell protection circuit; the drive circuit is used to control the on and off of the positive switch and the short-circuit switch according to the instructions of the microprocessor; the microprocessor processes information from each acquisition circuit, and determines the charge and discharge state of the single battery with the cell protection circuit according to a preset logic, and issues corresponding control instructions.

5. A cell-level protection circuit according to claim 4, characterized in that: It also includes an external communication circuit, which is connected to the microprocessor; the external communication circuit is used to transmit the status information of the battery module.

6. A cell-level protection circuit according to claim 4, characterized in that: When the battery module is in a normal charging state, the voltage acquisition circuit acquires the voltage across each single battery with a cell protection circuit, and feeds back the data to the microprocessor in real time, and the microprocessor monitors the voltage change of each single battery with a cell protection circuit in real time; if a single battery with a cell protection circuit reaches a critical fully charged state, that is, the voltage reaches a preset maximum charging voltage, the microprocessor disconnects the positive switch in the single battery with the cell protection circuit through the driving circuit, and cuts off the charging path of the single battery with the cell protection circuit; at the same time, the microprocessor turns on the short-circuit switch through the driving circuit to form a bypass.

7. A cell-level protection circuit according to claim 6, characterized in that: When the microprocessor confirms through the current acquisition circuit that the battery module is no longer in a charging state, that is, the charging current is less than the preset charging current threshold, the positive switch in the single battery with the battery cell protection circuit is reopened through the driving circuit, and the short-circuit switch is disconnected to restore the charging path of the single battery with the battery cell protection circuit.

8. A cell-level protection circuit according to claim 4, characterized in that: When the battery module is in a normal discharge state, the microprocessor continuously monitors the voltage and current parameters of each single cell with a battery cell protection circuit; when the power of a single cell with a battery cell protection circuit gradually decreases and is less than a preset discharge current threshold, the microprocessor disconnects the positive switch in the single cell with the battery cell protection circuit through the driving circuit; at the same time, the microprocessor turns on the short-circuit switch through the driving circuit to form a bypass.

9. A cell-level protection circuit according to claim 8, characterized in that: When the battery module completes the discharge task or reaches the predetermined discharge termination condition, the microprocessor controls the discharge process to stop; the microprocessor reconfigures the positive switch and the short-circuit switch in the single battery with the battery cell protection circuit, that is, re-turns on the positive switch and disconnects the short-circuit switch through the driving circuit.

10. A cell-level protection circuit according to claim 5, characterized in that: When the microprocessor determines that a single battery with a cell protection circuit has an overcharge or over-discharge fault, the state information of the single battery with a cell protection circuit is fed back to the background management system through the communication circuit; After receiving the status information, the background management system analyzes and processes the status information.

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