Battery protection method and apparatus, and battery charging and discharging circuit

Abstract

A battery protection method and apparatus, and a battery charging and discharging circuit, relating to the technical field of batteries, for use in protecting a battery in a battery charging and discharging circuit, wherein the battery charging and discharging circuit comprises a battery protection unit connected to the battery. The method comprises: determining that an interference current is present in the battery charging and discharging circuit when the battery protection unit is turned off (S1); acquiring a first voltage and a second voltage of the battery before and after the occurrence of the interference current (S2); determining a voltage increment of the battery on the basis of a preset current threshold (S3); and in response to the interference current being greater than a current threshold, and upon determining that the first voltage, the voltage increment and the second voltage meet preset conditions, controlling the battery charging and discharging circuit to disconnect from the battery (S4). In the method, when the battery protection unit is turned off, the interference current in the battery charging and discharging circuit and the voltages before and after the occurrence of the interference current are monitored, and when it is determined that the voltage after the occurrence of the interference current reaches a certain level and may cause damage to the battery, the battery is protected by controlling same to be permanently disabled.

Description

Battery protection method, device and charging and discharging circuit

[0001] The present application claims priority to the Chinese patent application No. 202411354382.8, filed on September 26, 2024, and entitled "Battery protection method, device and charging and discharging circuit", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] Embodiments of the present application relate to the technical field of battery, in particular to a battery protection method, device and charging and discharging circuit. BACKGROUND

[0003] There is a corresponding battery protection unit in the battery charging and discharging circuit. The battery protection unit is used to protect the battery by disconnecting the circuit when the battery fails during charging and discharging. When the battery protection unit is triggered to protect the action, if the circuit is disturbed by external interference to generate a virtual current, it will trigger the abnormal failure of the battery, resulting in the use of the device cannot be used normally. SUMMARY

[0004] Embodiments of the present application aim to provide a battery protection method, device and charging and discharging circuit to solve the technical problem that the existing technology will cause the use of the device to be unable to be used normally when the virtual current is generated in the battery circuit.

[0005] In order to solve the above technical problems, the embodiments of the present application disclose the following technical solutions:

[0006] In a first aspect, a battery protection method is provided for protecting a battery in a battery charging and discharging circuit, the battery charging and discharging circuit further comprising a battery protection unit connected to the battery; the method comprising:

[0007] determining that there is an interference current in the battery charging and discharging circuit when the battery protection unit is turned off;

[0008] obtaining a first voltage of the battery before the interference current appears and a second voltage of the battery after the interference current appears;

[0009] determining a voltage increment of the battery based on a preset current threshold;

[0010] in response to the interference current being greater than the current threshold, and determining that the first voltage, the voltage increment and the second voltage meet a preset condition, controlling the battery charging and discharging circuit to disconnect the connection with the battery.

[0011] In combination with the first aspect, the method of determining the voltage increment of the battery based on the preset current threshold comprises:

[0012] determining a real battery impedance before the interference current occurs;

[0013] obtaining the voltage increment based on the real battery impedance and the current threshold.

[0014] With reference to the first aspect, the method of determining the real battery impedance before the interference current occurs includes:

[0015] obtaining a remaining capacity of the battery before the interference current occurs;

[0016] obtaining the real battery impedance based on the remaining capacity of the battery.

[0017] With reference to the first aspect, before the real battery impedance is obtained based on the remaining capacity of the battery, the method further includes:

[0018] obtaining a temperature of the battery before the interference current occurs;

[0019] determining an impedance correction coefficient of the battery based on the temperature of the battery.

[0020] With reference to the first aspect, the method of obtaining the real battery impedance based on the remaining capacity of the battery includes:

[0021] determining a reference battery impedance corresponding to the remaining capacity of the battery based on a first mapping relationship of the battery;

[0022] obtaining the real battery impedance based on a product of the reference battery impedance and the impedance correction coefficient;

[0023] The first mapping relationship is configured to represent a corresponding relationship between the remaining capacity of the battery and the reference battery impedance at the same temperature.

[0024] With reference to the first aspect, the method of determining the impedance correction coefficient of the battery based on the temperature of the battery includes:

[0025] determining the impedance correction coefficient corresponding to the temperature of the battery based on a second mapping relationship of the battery;

[0026] The second mapping relationship is represented as a corresponding relationship between different temperatures of the battery and impedance correction coefficients, and the correction coefficient is represented as a correction of the reference battery impedance to obtain the real battery impedance.

[0027] With reference to the first aspect, the preset condition includes that a sum of the first voltage and the voltage increment is less than the second voltage.

[0028] With reference to the first aspect, before the connection between the battery charging and discharging circuit and the battery is controlled to be disconnected, the method further includes:

[0029] determine that the duration of the interference current is greater than a duration threshold.

[0030] In a second aspect, a battery protection device is provided for protecting a battery in a battery charging and discharging circuit, the battery charging and discharging circuit further comprising a battery protection unit connected to the battery; the device comprising:

[0031] a current monitoring module configured to determine that an interference current exists in the battery charging and discharging circuit when the battery protection unit is turned off;

[0032] a voltage monitoring module configured to obtain a first voltage of the battery before the interference current occurs and a second voltage of the battery after the interference current occurs;

[0033] an operation module configured to determine a voltage increment of the battery based on a preset current threshold;

[0034] a control module configured to control the battery charging and discharging circuit to disconnect from the battery in response to the interference current being greater than the current threshold and the first voltage, the voltage increment and the second voltage satisfying a preset condition.

[0035] In a third aspect, a battery charging and discharging circuit is provided, comprising:

[0036] a battery;

[0037] a battery protection unit connected to the battery;

[0038] a coulometer connected to the battery and the battery protection unit respectively;

[0039] a fuse unit connected between the battery and the battery protection unit, a control end of the fuse unit being connected to the coulometer;

[0040] wherein the coulometer is configured to control the fuse unit to fuse by using the battery protection method of any one of the first aspect.

[0041] One of the above technical solutions has the following advantages or beneficial effects:

[0042] The embodiment of the present application provides a battery protection method for protecting a battery in a battery charging and discharging circuit, wherein the battery charging and discharging circuit further comprises a battery protection unit connected with the battery; the method comprises the following steps: determining that there is an interference current in the battery charging and discharging circuit when the battery protection unit is turned off; obtaining a first voltage of the battery before the interference current appears and a second voltage of the battery after the interference current appears; determining a voltage increment of the battery based on a preset current threshold; and in response to the interference current being greater than the current threshold and the first voltage, the voltage increment and the second voltage satisfying a preset condition, controlling the battery charging and discharging circuit to disconnect the connection with the battery. The battery protection method provided by the present application monitors the current in the battery charging and discharging circuit after the battery protection unit is turned off, and when it is determined that the voltage after the current appears reaches a certain degree and will cause damage to the battery, the battery is permanently disabled to protect the battery.

[0043] The embodiment of the present application further provides a battery protection device for protecting a battery in a battery charging and discharging circuit, wherein the battery charging and discharging circuit further comprises a battery protection unit connected with the battery; the device comprises the following modules: a current monitoring module configured to determine that there is an interference current in the battery charging and discharging circuit when the battery protection unit is turned off; a voltage monitoring module configured to obtain a first voltage of the battery before the interference current appears and a second voltage of the battery after the interference current appears; an operation module configured to determine a voltage increment of the battery based on a preset current threshold; and a control module configured to, in response to the interference current being greater than the current threshold and the first voltage, the voltage increment and the second voltage satisfying a preset condition, control the battery charging and discharging circuit to disconnect the connection with the battery. The battery protection device provided by the present application monitors the current in the battery charging and discharging circuit after the battery protection unit is turned off through the current monitoring module, monitors the voltage change in the battery charging and discharging circuit through the voltage monitoring module, and when it is determined through the control module that the voltage after the current appears reaches a certain degree and will cause damage to the battery, the battery is permanently disabled to protect the battery.

[0044] The embodiment of the present application further provides a battery charging and discharging circuit, comprising: a battery; a battery protection unit connected with the battery; a power meter connected with the battery and the battery protection unit respectively; and a fuse unit connected between the battery and the battery protection unit, wherein the control end of the fuse unit is connected with the power meter; wherein the power meter is configured to control the fuse unit to fuse to protect the battery by using the battery protection method provided in any one of the above embodiments. The battery charging and discharging circuit provided by the present application monitors the current in the battery charging and discharging circuit after the battery protection unit is turned off through the power meter, simultaneously monitors the voltage change in the battery charging and discharging circuit, and when it is determined that the voltage after the current appears reaches a certain degree and will cause damage to the battery, the power meter controls the fuse unit to fuse to permanently disable the battery, thereby protecting the battery. BRIEF DESCRIPTION OF DRAWINGS

[0045] The technical solutions and other advantages of the present application will be apparent from the following detailed description of the application, taken in conjunction with the accompanying drawings.

[0046] Fig. 1 is a schematic diagram of the steps of the battery protection method according to an embodiment of the present application;

[0047] Fig. 2 is a schematic diagram of the steps of the method for obtaining the voltage increment according to an embodiment of the present application;

[0048] Fig. 3 is a schematic diagram of the module connection of the battery protection device according to an embodiment of the present application;

[0049] Fig. 4 is a schematic diagram of the structure connection of the battery charging and discharging circuit according to an embodiment of the present application. DETAILED DESCRIPTION

[0050] The technical solutions and other advantages of the present application will be apparent from the following detailed description of the application, taken in conjunction with the accompanying drawings.

[0051] In some embodiments of the present application, the charging and discharging circuit of a lithium battery is generally provided with a coulometer and a battery protection unit. The battery protection unit usually includes a charging protection switch provided in the charging circuit and a discharging protection switch provided in the discharging circuit (the charging protection switch is usually a charging MOS tube, and the discharging protection switch is usually a discharging MOS tube). When the coulometer detects that the charging and discharging circuit of the battery has conditions including overcharging, overdischarging, overcurrent, and temperature overcharge, etc., the coulometer can cut off the circuit by turning off the charging protection switch or the discharging protection switch, thereby playing a role in protecting the battery. This type of protection is a general protection for the battery. When the charging protection switch is turned off, the charging function of the battery will be disabled, and at this time the battery cannot be charged. When the discharging protection switch is turned off, the discharging function of the battery will be disabled, and at this time the battery cannot be discharged. It is worth noting that the general protection can turn on the charging protection switch and the discharging protection switch again through the coulometer, thereby restoring the charging and discharging function of the battery. In addition to the general protection, when the coulometer turns off the charging protection switch or the discharging protection switch, and when the coulometer still monitors the charging current or the discharging current in the battery charging and discharging circuit, the coulometer will start the permanent failure function of the battery, at which time the battery is permanently disabled, and this protection cannot be restored by the coulometer.

[0052] However, the skilled in the art of the present application notices that when the charging protection switch or the discharging protection switch is in the off state, the battery charging and discharging circuit is easy to be affected by the electromagnetic interference in the external environment to generate virtual current in the circuit, and the virtual current can trigger abnormal failure of the battery, resulting in that the electric device cannot be normally used.

[0053] Therefore, the embodiments of the present application provide a battery protection method, which dynamically adjusts the threshold of the virtual current according to the real-time state of the battery and the surrounding environment, so as to improve the safety and anti-interference ability of the battery, so as to solve the problem of abnormal failure of the battery, and avoid the problem that the user uses the electric device in the environment with complex electromagnetic environment, which easily causes the battery to fail, and further causes the system to be powered off.

[0054] The specific embodiments of the present application are described below through examples:

[0055] As shown in FIG. 1, the embodiments of the present application provide a battery protection method for protecting a battery in a battery charging and discharging circuit, and the battery charging and discharging circuit further includes a battery protection unit connected with the battery; the method includes:

[0056] S1: determining that there is an interference current in the battery charging and discharging circuit when the battery protection unit is off.

[0057] Specifically, the battery protection unit specifically includes a charging protection switch and a discharging protection switch, and the charging protection switch is used for protection of the battery in the charging process. When the charging protection switch is closed, the battery can normally charge. When overcharge, overcurrent and temperature overload and the like occur in the charging circuit, the charging protection switch is opened, and at this time the battery cannot continue to charge. By closing the charging protection switch, damage to the battery can be avoided. Similarly, when the discharging protection switch is closed, the battery can be discharging. When over-discharge, over-current and temperature overload occur in the discharging circuit, the discharging protection switch is opened, and at this time the battery cannot continue to discharge. By closing the discharging protection switch, damage to the battery or the electric device can be avoided. When the charging protection switch and the discharging protection switch are off, the battery charging and discharging circuit after being off is affected by the electromagnetic interference in the external environment to generate induced current, and the induced current is the interference current, which cannot be effectively charged and discharged.

[0058] In some embodiments of the present application, the battery protection unit can further include an overvoltage protection circuit, an undervoltage protection circuit and an overcurrent protection circuit and the like, and these protection circuits can also play a role in detecting and protecting the battery charging and discharging circuit to ensure that the battery works in a safe range.

[0059] In some embodiments of the present application, when the charging protection switch and the discharging protection switch are turned off, interference current can be caused due to sudden interruption of current or change of circuit state; or due to the internal resistance and capacitance characteristics of the battery itself, when the current is cut off or the circuit state is changed, the internal voltage of the battery can change, thereby generating interference current.

[0060] In embodiments of the present application, the interference current is usually monitored by using a current sensor, a current detection circuit or a power gauge provided by the battery itself. The current sensor can be connected to the battery charging and discharging circuit to monitor the change of current and interference in real time so as to take timely measures for protection. The current detection circuit can measure the size and direction of current and compare it with a preset threshold to determine whether there is interference current or abnormal situation. Through monitoring and detection, timely action can be taken to prevent the battery and circuit from being damaged. The power gauge is connected to the positive and negative poles of the battery, and the power gauge is also connected to the charging protection switch and the discharging protection switch, which can control the on-off of the charging protection switch and the discharging protection switch according to the situation in the circuit.

[0061] S2: obtaining a first voltage of the battery before the occurrence of the interference current and a second voltage of the battery after the occurrence of the interference current.

[0062] Specifically, in embodiments of the present application, the battery refers to a battery or a battery pack composed of one or more battery cells. The relevant parameters of the battery are obtained in real time by the power gauge, which include the current, voltage, resistance, temperature and remaining capacity in each battery cell of the battery. Through monitoring and judging these parameters, the current state of the battery can be obtained, and the future state of the battery can also be predicted.

[0063] In embodiments of the present application, the power gauge is used to monitor the relevant parameters of each battery cell in real time. When the power gauge monitors the change of current in the battery charging and discharging circuit, it is determined that interference current occurs, and the power gauge records the specific time when the interference current occurs, and records the first voltage of each battery cell in the battery before that time, for example, when the battery has three battery cells, the first voltage of the first battery cell is V0_Cell1, the first voltage of the second battery cell is V0_Cell2, and the first voltage of the third battery cell is V0_Cell3; the power gauge also needs to record the second voltage of each battery cell in the battery after the occurrence of the interference current, and for the same reason, the second voltage of the first battery cell is V1_Cell1, the second voltage of the second battery cell is V1_Cell2, and the second voltage of the third battery cell is V1_Cell3.

[0064] S3: determining the voltage increment of the battery based on a preset current threshold.

[0065] As shown in FIG. 2, the steps of specifically determining the voltage increment of the battery include:

[0066] S301: Determine the real battery impedance before the interference current occurs.

[0067] Specifically, the battery impedance is not constant, and generally changes with the remaining capacity and temperature of the battery. When the battery is continuously used to a certain extent and then continues to be used, the less the remaining capacity of the battery, the more the battery impedance increases with the decrease of the battery capacity. This is because, with the discharge process of the battery, the active material inside the battery is gradually depleted, the electrochemical reaction rate slows down, and the impedance inside the battery gradually increases. Therefore, by monitoring the change of the battery impedance, the remaining capacity of the battery can be inferred. The effect of temperature on the battery is just the opposite, as the temperature rises, the impedance of the battery generally decreases. This is because the increase in temperature increases the chemical reaction rate inside the battery, improves the conductivity of the electrolyte, reduces the polarization phenomenon at the electrode interface, thereby reducing the overall battery impedance. That is, the increase in temperature promotes the progress of the reaction inside the battery, improves the ion migration rate inside the battery, reduces the negative effects inside the battery, and thus reduces the battery impedance. Therefore, when considering the impedance of the battery, the effect of temperature needs to be considered and corrected accordingly.

[0068] In the embodiments of the present application, when the interference current occurs in the battery charging and discharging circuit, the remaining capacity and temperature of the battery will be affected and changed to a certain extent, so the impedance in the battery charging and discharging circuit also changes. In order to obtain the accurate battery increment after the interference current occurs in the battery charging and discharging circuit, the real battery impedance before the interference current occurs needs to be obtained, so as to facilitate the calculation of the battery increment.

[0069] Therefore, in the embodiments of the present application, the remaining capacity of the battery before the interference current occurs needs to be obtained, which is measured and recorded by the coulomb counter in real time (or obtained by using other battery remaining capacity measurement methods in real time), and is at the same time as the first voltage, so as to avoid the deviation of the calculation result caused by the asynchronization of the battery remaining capacity and the first voltage. After obtaining the remaining capacity of the battery, the reference battery impedance corresponding to the remaining capacity of the battery is determined based on the first mapping relationship of the battery, and the first mapping relationship is configured to represent the corresponding relationship between the remaining capacity of the battery and the reference battery impedance at the same temperature. The first mapping relationship is shown in Table 1 and Table 2.

[0070] Table 1

[0071] Table 2

[0072] In Table 1, ChgR0-ChgR14 represent 15 discharge nodes, which are obtained by dividing the whole discharge process of the battery from 100% to 0% into 15 equal parts. Table 2 discloses the relationship between the battery remaining capacity and the reference battery impedance during the charging process of the battery; at the beginning of charging, the reference battery impedance is large, and as the battery remaining capacity increases, the reference battery impedance gradually tends to be flat and fluctuates up and down, and when the battery remaining capacity is close to Ra14, the reference battery impedance becomes large. In Table 2, Ra0-Ra14 represent 15 charging nodes, which are obtained by dividing the whole charging process of the battery from 100% to 0% into 15 equal parts.

[0073] In the embodiments of the present application, after the reference battery impedance is determined, the battery temperature before the interference current occurs is further obtained, which is recorded by the coulometer in real time (or measured by a temperature sensor, etc.) and at the same time as the first voltage, so as to avoid the deviation of the calculation result caused by the asynchronization of the first voltage and the battery temperature. The impedance correction coefficient of the battery is determined by the battery temperature to correct the reference battery impedance. The impedance correction coefficient is determined based on the second mapping relationship of the battery; the second mapping relationship is characterized by the corresponding relationship between different battery temperatures and the impedance correction coefficient, and the correction coefficient is characterized by correcting the reference battery impedance to obtain the real battery impedance. The second mapping relationship is disclosed in detail in Table 3 below.

[0074] Table 3

[0075] In Table 3, the relationship between the battery temperature and the impedance correction coefficient during the charging and discharging process of the battery is disclosed, and it can be seen from the table that the impedance correction coefficient increases with the increase of the battery temperature, that is, the larger the battery temperature, the larger the impedance correction coefficient.

[0076] Therefore, the reference battery impedance can be determined by the battery remaining capacity through the first mapping relationship of Table 1 and Table 2, and the impedance correction coefficient at the battery temperature can be determined by combining the second mapping relationship of Table 3, and the real battery impedance is finally obtained by the product of the reference battery impedance and the impedance correction coefficient.

[0077] Taking a battery with three cells as an example, the calculation formula of the real battery impedance of the three cells is: R_Cell1=Ra_Cell1xF; (1) R_Cell2=Ra_Cell2xF; (2) R_Cell3=Ra_Cell3xF. (3)

[0078] In the above formula, R_Cell1 represents the real battery impedance of the first cell; R_Cell2 represents the real battery impedance of the second cell; R_Cell3 represents the real battery impedance of the third cell; Ra_Cell1 represents the reference battery impedance during the charging process of the first cell; Ra_Cell2 represents the reference battery impedance during the charging process of the second cell; Ra_Cell3 represents the reference battery impedance during the charging process of the third cell; and F represents the impedance correction coefficient.

[0079] It should be noted that when the battery is in the discharging process, the formula (1) to (3) can be rewritten as: R_Cell1=ChgRa_Cell1xF; (1) R_Cell2=ChgRa_Cell2xF; (2) R_Cell3=ChgRa_Cell3xF. (3)

[0080] In the above formula, ChgRa_Cell1 represents the reference battery impedance during the discharging process of the first cell; ChgRa_Cell2 represents the reference battery impedance during the discharging process of the second cell; and ChgRa_Cell3 represents the reference battery impedance during the discharging process of the third cell.

[0081] S302: Obtain a voltage increment based on the real battery impedance and the current threshold.

[0082] Specifically, according to Ohm's law, the resistance multiplied by the current is equal to the voltage, so after obtaining the real battery impedance, the real battery impedance is multiplied by the current threshold to obtain the voltage increment. The voltage increment is used to determine whether the interference current appearing in the battery charging and discharging loop will affect the battery.

[0083] Taking a battery with three cells as an example, after obtaining the real battery impedance of the three cells, the calculation formula of the voltage increment of the three cells is: ΔV_Cell1=R_Cell1xI s ; (4) ΔV_Cell2=R_Cell2xI s ; (5) ΔV_Cell3=R_Cell3xI s ; (6)

[0084] In the above formula, ΔV_Cell1 represents the voltage increment of the first battery cell; ΔV_Cell2 represents the voltage increment of the second battery cell; ΔV_Cell3 represents the voltage increment of the third battery cell; I s represents the current threshold.

[0085] S4: in response to the interference current being greater than the current threshold and determining that the first voltage, the voltage increment and the second voltage meet the preset condition, controlling the battery charging and discharging circuit to disconnect the connection with the battery.

[0086] Specifically, it is first needed to determine whether the interference current is greater than the current threshold, and the current threshold is determined by the full charging capacity of the battery. Generally, the current threshold is one-tenth to one-fifth of the full charging capacity of the battery. For example, when the full charging capacity of a battery is 4000 mAh, the current threshold of the battery is 400 mA to 800 mA. When the interference current is much smaller than the current threshold, for example, the current threshold is 400 mA and the interference current is 120 mA, at this time, the interference current has less impact on the normal use of the battery and the electric device. When the interference current is close to or greater than the current threshold, the interference current has more obvious impact on the normal use of the battery and the electric device. Therefore, it is needed to determine the battery voltage after the interference current occurs, and determine whether the interference current will have an impact on the battery and the electric device by combining the size of the interference current and the size of the battery voltage. If there is an impact, the battery is permanently disabled to avoid damage to the battery or the electric device.

[0087] In the embodiments of the present application, after it is determined that the interference current is greater than the current threshold, the interference current needs to be continuously monitored to determine whether the interference current will persist, so as to avoid the power meter misjudgment caused by some short-term appearing and disappearing interference currents. When the duration of the interference current in the battery charging and discharging circuit is greater than the duration threshold, it is indicated that the interference current has a persistent impact on the battery charging and discharging circuit. The value range of the duration threshold is 8-12 s, and the values that can be selected include but are not limited to 8.0 s, 8.2 s, 8.5 s, 8.8 s, 9.0 s, 9.2 s, 9.5 s, 9.8 s, 10.0 s, 10.2 s, 10.5 s, 10.8 s, 11.0 s, 11.2 s, 11.5 s, 11.8 s, 12.0 s. By setting the duration threshold in the power meter, the duration of the interference current can be effectively determined, so as to avoid misjudgment of the interference current.

[0088] In the embodiments of the present application, after it is determined that the interference current is greater than the current threshold and the duration of the interference current is greater than the duration threshold, it is finally determined whether the sum of the first voltage and the voltage increment is less than the second voltage. The preset condition is configured to represent the size relationship between the sum of the first voltage and the voltage increment and the second voltage. The first voltage is the battery voltage before the interference current occurs, and the second voltage is the battery voltage after the interference current occurs. Before the interference current occurs, the battery voltage is always in a stable state. When the interference current occurs, a voltage surge will occur in the battery charging and discharging circuit, thereby breaking the stable state of the battery voltage, that is, the second voltage is greater than the first voltage. Therefore, the sum of the first voltage and the voltage increment is taken as the voltage threshold, and the second voltage is compared with the voltage threshold. If the second voltage is greater than or equal to the voltage threshold, it indicates that the voltage surge caused by the interference current has a greater impact on the battery circuit, and there is a risk of damaging the battery and the electrical equipment. If the second voltage is less than the voltage threshold, it indicates that the voltage surge caused by the interference current has a smaller impact on the battery circuit, and will not affect the battery and the electrical equipment.

[0089] Taking a battery with three cells as an example, the formula for comparing the first voltage, the voltage increment and the second voltage of the three cells is: V0_Cell1+ΔV_Cell1<V1_Cell1; (7) V0_Cell2+ΔV_Cell2<V1_Cell2; (8) V0_Cell3+ΔV_Cell3<V1_Cell3; (9)

[0090] In the above formula, ΔV_Cell1 represents the voltage increment of the first cell; ΔV_Cell2 represents the voltage increment of the second cell; ΔV_Cell3 represents the voltage increment of the third cell; I s represents the current threshold.

[0091] As shown in FIG. 3, the embodiment of the present application further provides a battery protection device for protecting a battery in a battery charging and discharging circuit, the battery charging and discharging circuit further comprising a battery protection unit connected with the battery; the device comprises: a current monitoring module configured to determine an interference current in the battery charging and discharging circuit when the battery protection unit is turned off. Specifically, the current monitoring module comprises components or circuits capable of monitoring current, such as a power meter, an ammeter and a current sensor. A voltage monitoring module configured to obtain a first voltage of the battery before the interference current appears and a second voltage of the battery after the interference current appears. Specifically, the voltage monitoring module comprises components or circuits capable of monitoring voltage, such as a power meter, a voltmeter and a voltage sensor. An operation module configured to determine a voltage increment of the battery based on a preset current threshold. Specifically, the operation module comprises components or circuits capable of calculating the voltage increment through the current threshold, such as a power meter and a logic operation circuit. A control module configured to, in response to the interference current being greater than the current threshold and the first voltage, the voltage increment and the second voltage satisfying a preset condition, permanently disable the battery. Specifically, the control module comprises chips, components or circuits capable of comparing, judging and sending control signals to the first voltage, the second voltage and the voltage increment, such as a power meter, a control chip and a control circuit. The embodiment of the present application can monitor the interference current in the battery charging and discharging circuit through the current monitoring module when the protection unit of the battery is turned off by connecting the battery protection device between the battery and the electrical equipment, monitor the voltage change in the battery charging and discharging circuit through the voltage monitoring module, and protect the battery by permanently disabling the battery when the voltage after the interference current appears reaches a certain degree and will cause damage to the battery through the control module.

[0092] As shown in FIG. 4, the embodiment of the present application further provides a battery charging and discharging circuit, comprising: a battery S; a battery protection unit, the battery protection unit comprising a first protection switch Q1 and a second protection switch Q2, the first protection switch Q1 and the second protection switch Q2 being connected in series and then connected with the battery S; a coulometer, the coulometer being connected with the battery S, the first protection switch Q1 and the second protection switch Q2; a fuse unit F1, the fuse unit F1 being connected between the battery S and the battery protection unit, and a control end of the fuse unit F1 being connected with the coulometer; wherein the coulometer is configured to control the fuse unit F1 to fuse by using the battery protection method in any one of the above, so as to protect the battery. Specifically, the battery charging and discharging circuit further comprises a third protection switch Q3 and a precision resistor RS1. In the battery charging and discharging circuit, the fuse unit F1 is a three-terminal fuse, comprising a first end, a second end and a fuse control end, the first protection switch Q1, the second protection switch Q2 and the third protection switch Q3 are all MOS tubes, and a first interface P+ and a second interface P- are used for connecting an electrical equipment. Wherein, a positive electrode of the battery is connected with the first end of the fuse unit F1, the second end of the fuse unit F1 is connected with an input end (a source electrode of the MOS tube) of the first protection switch Q1, an output end (a drain electrode of the MOS tube) of the first protection switch Q1 is connected with an output end of the second protection switch Q2, an input end of the second protection switch Q2 is the first interface P+, a control end (a gate electrode of the MOS tube) of the first protection switch Q1 is connected with a CHG pin of the coulometer, a control end of the second protection switch Q2 is connected with a DSG pin of the coulometer, an input end of the third protection switch Q3 is connected with a negative electrode of the battery, an output end of the third protection switch Q3 is connected with the fuse control end of the fuse unit F1, and a control end of the third protection switch Q3 is connected with a FUSE pin of the coulometer. A VC1 pin and a VC2 pin of the coulometer are connected with positive electrode ends of battery cells in the battery, for obtaining voltages of each battery cell. Two ends of the precision resistor RS1 are connected with an SRP pin and an SRN pin of the coulometer, for obtaining a current in the battery charging and discharging circuit. When general protection occurs in the battery charging and discharging circuit, that is, the first protection switch Q1 or the second protection switch Q2 is turned off, the coulometer will monitor the current in the battery charging circuit or the discharging circuit, when the coulometer monitors an interference current, whether the interference current will cause damage to the battery or the electrical equipment is determined by judging the size, duration and voltage difference before and after the interference current. When the coulometer determines that the voltage after the interference current reaches a certain degree and will cause damage to the battery, the coulometer controls the third protection switch Q3 to be turned on to fuse the fuse unit F1 to make the battery permanently invalid, so as to protect the battery.

[0093] The above has carried out the detailed introduction to the battery protection method, the device and the charge-discharge circuit provided by the embodiment of the application, the principle and the implementation mode of the application are described in this paper, the above embodiment is only used to help understanding the technical scheme of the application and its core idea; the ordinary skilled in the art should understand that: it can still modify the technical scheme recorded by the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical scheme deviate from the scope of the technical scheme of the embodiments of the application.

Claims

1. A battery protection method, characterized by, The application discloses a method for protecting a battery in a battery charging and discharging circuit, wherein the battery charging and discharging circuit further comprises a battery protection unit connected with the battery; the method comprises the following steps: determining that there is an interference current in the battery charging and discharging circuit when the battery protection unit is turned off; obtaining a first voltage of the battery before the interference current appears and a second voltage of the battery after the interference current appears; determining a voltage increment of the battery based on a preset current threshold value; in response to the interference current being greater than the current threshold value and the first voltage, the voltage increment and the second voltage satisfying a preset condition, controlling the battery charging and discharging circuit to be disconnected from the battery.

2. The battery protection method of claim 1, wherein, The method for determining the voltage increment of the battery based on the preset current threshold value comprises the following steps: determining a real battery impedance before the interference current appears; obtaining the voltage increment based on the real battery impedance and the current threshold value.

3. The battery protection method of claim 2, wherein, The method for obtaining the real battery impedance before the interference current appears comprises the following steps: obtaining a remaining capacity of the battery before the interference current appears; obtaining the real battery impedance based on the remaining capacity of the battery.

4. The battery protection method of claim 3, wherein, Before obtaining the real battery impedance based on the remaining capacity of the battery, the method further comprises the following steps: obtaining a battery temperature before the interference current appears; determining an impedance correction coefficient of the battery based on the battery temperature.

5. The battery protection method of claim 4, wherein, The method for obtaining the real battery impedance based on the remaining capacity of the battery comprises the following steps: determining a reference battery impedance corresponding to the remaining capacity of the battery based on a first mapping relationship of the battery; obtaining the real battery impedance based on a product of the reference battery impedance and the impedance correction coefficient; wherein the first mapping relationship is configured to represent a corresponding relationship between the remaining capacity of the battery and the reference battery impedance at the same temperature.

6. The battery protection method of claim 5, wherein, The method for determining the impedance correction coefficient of the battery based on the battery temperature comprises the following steps: determining the impedance correction coefficient corresponding to the battery temperature based on a second mapping relationship of the battery; the second mapping relationship is represented as a corresponding relationship between different battery temperatures and impedance correction coefficients, and the correction coefficient is represented as a correction coefficient for correcting the reference battery impedance to obtain the real battery impedance.

7. The battery protection method of claim 1, wherein, The preset condition comprises that a sum of the first voltage and the voltage increment is less than the second voltage.

8. The battery protection method of claim 7, wherein, Before controlling the battery charging and discharging circuit to be disconnected from the battery, the method further comprises the following steps: determining that a duration of the interference current is greater than a duration threshold value.

9. A battery protection device, characterized by The application discloses a device for protecting a battery in a battery charging and discharging circuit, wherein the battery charging and discharging circuit further comprises a battery protection unit connected with the battery; the device comprises the following steps: a current monitoring module configured to determine that there is an interference current in the battery charging and discharging circuit when the battery protection unit is turned off; a voltage monitoring module configured to obtain a first voltage of the battery before the interference current appears and a second voltage of the battery after the interference current appears; an operation module configured to determine a voltage increment of the battery based on a preset current threshold value; A control module configured to, in response to the interference current being greater than the current threshold value and determining that the first voltage, the voltage increment and the second voltage satisfy a preset condition, control the battery charging and discharging circuit to disconnect from the battery.

10. A battery charging and discharging circuit, characterized by comprising: Comprise: a battery; a battery protection unit connected with the battery; a coulometer connected with the battery and the battery protection unit respectively; a fuse unit connected between the battery and the battery protection unit, a control end of the fuse unit being connected with the coulometer; wherein the coulometer is configured to control the fuse unit to fuse by using the battery protection method in any one of claims 1-8 to protect the battery.

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