Battery protection method, device and charging and discharging circuit

Abstract

The present application discloses a battery protection method, device and charge-discharge circuit, which belongs to the field of battery technology and is used to protect batteries in the battery charge-discharge circuit, wherein the battery charge-discharge circuit also includes a battery protection unit connected to the battery; the method includes: determining that there is an interference current in the battery charge-discharge circuit when the battery protection unit is turned off; obtaining the first voltage and the second voltage of the battery before and after the interference current appears; determining the voltage increment of the battery based on a preset current threshold; 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 conditions, controlling the battery charge-discharge circuit to disconnect from the battery. The battery protection method provided in the present application monitors the current in the battery charge-discharge circuit and the voltage before and after the current appears after the battery protection unit is turned off, and when it is determined that the voltage after the current appears reaches a certain level and will cause damage to the battery, the battery is protected by controlling the battery to fail permanently.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of battery technology, and in particular to a battery protection method, device and charging and discharging circuit. Background Art

[0002] 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 a battery failure occurs during the charging and discharging process. When the battery protection unit is triggered to take protective action, if the circuit is disturbed by external interference and generates virtual current, it will trigger abnormal failure of the battery, causing the electrical equipment to be unable to be used normally. Summary of the invention

[0003] The embodiments of the present application aim to provide a battery protection method, device and charging and discharging circuit to solve the technical problem in the prior art that when a virtual current is generated in a battery circuit, the electrical equipment cannot be used normally.

[0004] In order to solve the above technical problems, the embodiments of the present application disclose the following technical solutions:

[0005] In a first aspect, a battery protection method is provided for protecting a battery in a battery charging and discharging circuit, wherein the battery charging and discharging circuit further includes a battery protection unit connected to the battery; the method includes:

[0006] Determining that interference current exists in the battery charging and discharging circuit when the battery protection unit is turned off;

[0007] Acquire a first voltage of the battery before the interference current appears and a second voltage of the battery after the interference current appears;

[0008] determining a voltage increment of the battery based on a preset current threshold;

[0009] 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 satisfy a preset condition, the battery charge and discharge circuit is controlled to disconnect from the battery.

[0010] In combination with the first aspect, the method for determining the voltage increment of the battery based on a preset current threshold includes:

[0011] determining the actual battery impedance before the interfering current appears;

[0012] The voltage increment is obtained based on the actual battery impedance and the current threshold.

[0013] In combination with the first aspect, the method for obtaining the real battery impedance before the interference current appears includes:

[0014] Obtaining the remaining capacity of the battery before the interference current occurs;

[0015] The real battery impedance is obtained based on the battery remaining capacity.

[0016] In combination with the first aspect, before obtaining the real battery impedance based on the remaining battery capacity, the method further includes:

[0017] Acquiring the battery temperature before the interference current appears;

[0018] An impedance correction factor for the battery is determined based on the battery temperature.

[0019] In combination with the first aspect, the method for obtaining the real battery impedance based on the remaining battery capacity includes:

[0020] Determining a reference battery impedance corresponding to the remaining capacity of the battery based on a first mapping relationship of the battery;

[0021] Obtaining the real battery impedance based on the product of the reference battery impedance and the impedance correction coefficient;

[0022] 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 of the battery.

[0023] In combination with the first aspect, a method for determining an impedance correction coefficient of the battery based on the battery temperature includes:

[0024] Determining an impedance correction coefficient corresponding to the battery temperature based on a second mapping relationship of the battery;

[0025] The second mapping relationship is characterized as a correspondence between different battery temperatures and impedance correction coefficients, and the correction coefficient is characterized by correcting the reference battery impedance to obtain the real battery impedance.

[0026] In combination with the first aspect, the preset condition includes that the sum of the first voltage and the voltage increment is less than the second voltage.

[0027] In combination with the first aspect, before controlling the battery charging and discharging circuit to disconnect from the battery, the method further includes:

[0028] It is determined that the duration of the interference current is greater than a duration threshold.

[0029] In a second aspect, a battery protection device is provided for protecting a battery in a battery charging and discharging circuit, wherein the battery charging and discharging circuit further includes a battery protection unit connected to the battery; the device includes:

[0030] a current monitoring module, the current monitoring module being configured to determine whether interference current exists in the battery charging and discharging circuit when the battery protection unit is turned off;

[0031] A voltage monitoring module, wherein the voltage monitoring module is 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;

[0032] A calculation module, wherein the calculation module is configured to determine a voltage increment of the battery based on a preset current threshold;

[0033] A control module is configured to control the battery charge and discharge circuit to disconnect from the battery 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.

[0034] In a third aspect, a battery charging and discharging circuit is provided, comprising:

[0035] Battery;

[0036] A battery protection unit, wherein the battery protection unit is connected to the battery;

[0037] A fuel gauge, the fuel gauge is connected to the battery and the battery protection unit respectively;

[0038] A fuse unit, the fuse unit is connected between the battery and the battery protection unit, and a control end of the fuse unit is connected to the electricity meter;

[0039] The fuel gauge is configured to control the fuse unit to fuse using the battery protection method described in any one of the first aspects to protect the battery.

[0040] One of the above technical solutions has the following advantages or beneficial effects:

[0041] The embodiment of the present application provides a battery protection method for protecting a battery in a battery charge and discharge circuit, wherein the battery charge and discharge circuit also includes a battery protection unit connected to the battery; the method includes: determining that an interference current exists in the battery charge and discharge 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; 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 preset conditions, controlling the battery charge and discharge circuit to disconnect from the battery. The battery protection method provided in the present application monitors the current in the battery charge and discharge circuit after the battery protection unit is turned off, and when it is determined that the voltage after the current appears reaches a certain level and will cause damage to the battery, the battery is protected by controlling the battery to fail permanently.

[0042] The embodiment of the present application also provides a battery protection device for protecting a battery in a battery charging and discharging circuit, wherein the battery charging and discharging circuit also includes a battery protection unit connected to the battery; the device includes: a current monitoring module, the current monitoring module is 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, the voltage monitoring module is 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, the operation module is configured to determine the voltage increment of the battery based on a preset current threshold; a control module, the control module is 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 determining that the first voltage, the voltage increment and the second voltage meet the preset conditions. 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 protects the battery by controlling the battery to fail permanently when the control module determines that the voltage after the current appears reaches a certain level and will cause damage to the battery.

[0043] The embodiment of the present application also provides a battery charging and discharging circuit, including: a battery; a battery protection unit, the battery protection unit is connected to the battery; a fuel meter, the fuel meter is respectively connected to the battery and the battery protection unit; a fuse unit, the fuse unit is connected between the battery and the battery protection unit, and the control end of the fuse unit is connected to the fuel meter; wherein the fuel meter is configured to control the fuse unit to fuse using the battery protection method provided in any of the above embodiments to protect the battery. 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 fuel meter, and monitors the voltage change in the battery charging and discharging circuit at the same time. When it is determined that the voltage after the current appears reaches a certain level and will cause damage to the battery, the fuel meter controls the fuse unit to fuse to make the battery permanently fail, thereby protecting the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0045] Figure 1 A schematic diagram of the steps of the battery protection method provided in an embodiment of the present application;

[0046] Figure 2 A schematic diagram of the steps of a method for obtaining a voltage increment provided in an embodiment of the present application;

[0047] Figure 3 A schematic diagram of module connection of a battery protection device provided in an embodiment of the present application;

[0048] Figure 4 A schematic diagram of the structural connection of a battery charging and discharging circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0050] In some embodiments of the present application, a fuel meter and a battery protection unit are generally provided in the charging and discharging circuit of the lithium battery. The battery protection unit generally 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 generally a charging MOS tube, and the discharging protection switch is generally a discharging MOS tube). When the fuel meter detects that the charging and discharging circuit of the battery has conditions including overcharging, over-discharging, overcurrent and overtemperature, the fuel meter can cut off the circuit by turning off the charging protection switch or the discharging protection switch, thereby protecting the battery. This type of protection is a general protection of the battery. When the charging protection switch is turned off, the charging function of the battery will be disabled, and the battery cannot be charged at this time; when the discharging protection switch is turned off, the discharging function of the battery will be disabled, and the battery cannot be discharged at this time. It is worth noting that the general protection can restore the charging and discharging functions of the battery by re-turning on the charging protection switch and the discharging protection switch through the fuel meter. In addition to general protection, when the fuel gauge turns off the charging protection switch or the discharging protection switch, when the fuel gauge still monitors the charging current or the discharging current in the battery charging and discharging circuit, the fuel gauge will activate the permanent failure function of the battery. At this time, the battery is permanently disabled and this protection fuel gauge cannot be restored.

[0051] However, relevant technicians of this application have noticed that when the charging protection switch or the discharging protection switch is in the off state, the battery charging and discharging circuit is susceptible to electromagnetic interference in the external environment, generating virtual currents in the circuit, and these virtual currents will trigger abnormal failure of the battery, causing the electrical equipment to be unable to be used normally.

[0052] To this end, an embodiment of the present application provides a battery protection method by dynamically adjusting the threshold of the virtual current according to the surrounding environment and the real-time status of the battery, thereby improving the safety and anti-interference ability of the battery to cope with the problem of abnormal battery failure and avoiding the problem of battery failure that may easily cause system power outages when users use electrical equipment in a complex electromagnetic environment.

[0053] The specific implementation methods of the present application are described below by way of examples:

[0054] like Figure 1 As shown, an 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 includes a battery protection unit connected to the battery; the method includes:

[0055] S1: Determine whether there is interference current in the battery charging and discharging circuit when the battery protection unit is turned off.

[0056] Specifically, the battery protection unit specifically includes a charging protection switch and a discharging protection switch. The charging protection switch is used to protect the battery during the charging process. When the charging protection switch is closed, the battery can be charged normally. When overcharging, overcurrent and overtemperature occur in the charging circuit, the charging protection switch is disconnected, and the battery cannot continue to be charged. By turning off the charging protection switch, damage to the battery can be avoided. Similarly, when the discharging protection switch is closed, the battery can be discharged. When overdischarge, overcurrent and overtemperature occur in the discharging circuit, the discharging protection switch is disconnected, and the battery cannot continue to be discharged. By turning off the discharging protection switch, damage to the battery or electrical equipment can be avoided. When the charging protection switch and the discharging protection switch are turned off, they are affected by electromagnetic interference in the external environment, and an induced current will be generated in the battery charging and discharging circuit after the shutdown. The induced current is the interference current, and the interference current cannot be effectively charged and discharged.

[0057] In some embodiments of the present application, the battery protection unit may also include an overvoltage protection circuit, an undervoltage protection circuit, and an overcurrent protection circuit, etc. These protection circuits can also play a role in detecting and protecting the battery charging and discharging circuit to ensure that the battery operates within a safe range.

[0058] In some embodiments of the present application, when the charging protection switch and the discharging protection switch are turned off, interference current may be caused due to the sudden interruption of current or change of circuit state; or because the battery itself has internal resistance and capacitance characteristics, when the current is cut off or the circuit state is changed, it may cause changes in the internal voltage of the battery, thereby generating interference current.

[0059] In an embodiment of the present application, a current sensor, a current detection circuit or a fuel gauge of the battery itself is generally used to monitor interference current. The current sensor can be connected to the battery charge and discharge circuit to monitor the changes and interference of the current in real time so that timely measures can be taken for protection. The current detection circuit can measure the magnitude and direction of the current and compare it with a preset threshold to determine whether there is interference current or abnormal conditions. Through monitoring and detection, timely action can be taken to prevent damage to the battery and the circuit. The fuel gauge is connected to the positive and negative poles of the battery, and the fuel gauge is also connected to the charging protection switch and the discharging protection switch, and the on and off of the charging protection switch and the discharging protection switch can be controlled according to the situation in the circuit.

[0060] S2: Acquire a first voltage of the battery before the interference current appears and a second voltage of the battery after the interference current appears.

[0061] Specifically, in the embodiments of the present application, the battery refers to a battery or battery pack composed of one or more cells. The relevant parameters of the battery are obtained in real time through the fuel gauge, and these parameters include the current, voltage, resistance, temperature and remaining capacity of each cell in the battery. By 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.

[0062] In an embodiment of the present application, the fuel meter is used to monitor the relevant parameters of each battery cell in real time. When the fuel meter monitors the current change in the battery charging and discharging circuit, it determines that an interference current occurs. The fuel meter records the specific time when the interference current occurs, and at the same time records the first voltage of each battery cell in the battery before that time. Taking a battery with three batteries as an example, 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 fuel meter also needs to record the second voltage of each battery cell in the battery after the interference current occurs. Similarly, 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.

[0063] S3: Determine the voltage increment of the battery based on a preset current threshold.

[0064] like Figure 2 As shown, the specific steps of determining the voltage increment of the battery include:

[0065] S301: Determine the real battery impedance before the interference current appears.

[0066] Specifically, the battery impedance is not static, and usually changes with the remaining capacity and temperature of the battery. When the battery is used continuously to a certain extent and then continues to be used, the less the remaining capacity of the battery, the more the battery impedance will increase as the battery capacity decreases. This is because as the battery discharges, the active substances inside the battery are gradually exhausted, the electrochemical reaction rate slows down, and the impedance inside the battery gradually increases. Therefore, the remaining capacity of the battery can be inferred by monitoring the impedance change of the battery. The effect of temperature on the battery is just the opposite. As the temperature rises, the impedance of the battery usually decreases. This is because the increase in temperature will increase the chemical reaction rate inside the battery, increase the conductivity of the electrolyte, and reduce the polarization phenomenon at the electrode interface, thereby reducing the overall battery impedance. That is, the increase in temperature will promote the reaction inside the battery, increase the migration rate of ions inside the battery, reduce the negative effects in the battery, and thus reduce the battery impedance. Therefore, when considering the impedance of the battery, it is necessary to consider the influence of temperature and make corresponding corrections.

[0067] In the embodiment of the present application, when interference current appears in the battery charge and discharge circuit, the remaining capacity and temperature of the battery will be affected and changed to a certain extent, so the impedance in the battery charge and discharge circuit also changes. In order to obtain the accurate battery increment of the battery charge and discharge circuit after the interference current appears, it is necessary to obtain the real battery impedance before the interference current appears, so as to facilitate the calculation of the battery increment.

[0068] Therefore, in the embodiment of the present application, it is necessary to first obtain the remaining battery capacity before the interference current appears. The remaining battery capacity is measured and recorded in real time by the fuel gauge (or obtained by real-time measurement using other remaining battery capacity measurement methods) and is at the same time as the first voltage to avoid the deviation in the calculation result caused by the remaining battery capacity being out of sync with the first voltage. After obtaining the remaining battery capacity, the reference battery impedance corresponding to the remaining battery capacity is determined based on the first mapping relationship of the battery. The first mapping relationship is configured to characterize the corresponding relationship between the remaining battery capacity and the reference battery impedance at the same temperature. The first mapping relationship is detailed in Tables 1 and 2 below.

[0069] Table 1

[0070]

[0071] Table 2

[0072]

[0073] Among them, Table 1 discloses the relationship between the remaining capacity of the battery and the reference battery impedance during the discharge process. As shown in the data in Table 1, after the battery is fully charged, at the beginning of discharge, the reference battery impedance fluctuates up and down with the amount of battery discharge. When discharged to the discharge node of ChgR9, the reference battery impedance gradually increases as the remaining capacity of the battery decreases. In Table 1, ChgR0~ChgR14 represent 15 discharge nodes, and the 15 discharge nodes are obtained by dividing the entire discharge process of the battery from 100% to 0% into 15 parts. Table 2 discloses the relationship between the remaining capacity of the battery and the reference battery impedance during the charging process; at the beginning of charging, the reference battery impedance is large, and as the remaining capacity of the battery increases, the reference battery impedance gradually tends to be flat and fluctuates up and down. When the remaining capacity of the battery is charged close to Ra14, the reference battery impedance becomes larger. In Table 2, Ra0~Ra14 represent 15 charging nodes, and the 15 charging nodes are obtained by dividing the entire charging process of the battery from 100% to 0% into 15 parts.

[0074] In an embodiment of the present application, after determining the reference battery impedance, the battery temperature before the interference current appears is further obtained. The battery temperature is recorded in real time by the fuel gauge (or measured and recorded in real time using a temperature sensor, etc.) and is at the same time as the first voltage to avoid the deviation in the calculation result caused by the first voltage and the battery temperature being out of sync. 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 as the corresponding relationship between different battery temperatures and the impedance correction coefficient, and the correction coefficient is characterized as correcting the reference battery impedance to obtain the real battery impedance. The second mapping relationship is detailed in Table 3 below.

[0075] Table 3

[0076]

[0077] Among them, Table 3 discloses the relationship between the battery temperature and the impedance correction coefficient during the charging and discharging process of the battery. It can be seen from the table that the impedance correction coefficient increases with the increase of the battery temperature, that is, the higher the battery temperature, the greater the impedance correction coefficient.

[0078] Therefore, the reference battery impedance can be determined by the remaining battery capacity through the first mapping relationship in Table 1 and Table 2, and the impedance correction coefficient at the battery temperature can be determined by combining the second mapping relationship in Table 3. The real battery impedance is finally obtained by multiplying the reference battery impedance by the impedance correction coefficient.

[0079] Taking a battery with three cells as an example, the calculation formula for the actual battery impedance of the three cells is:

[0080] R_Cell1=Ra_Cell1×F; (1)

[0081] R_Cell2=Ra_Cell2×F; (2)

[0082] R_Cell3=Ra_Cell3×F. (3)

[0083] In the above formula, R_Cell1 represents the real battery impedance of the first battery cell; R_Cell2 represents the real battery impedance of the second battery cell; R_Cell3 represents the real battery impedance of the third battery cell; Ra_Cell1 represents the reference battery impedance during the charging process of the first battery cell; Ra_Cell2 represents the reference battery impedance during the charging process of the second battery cell; Ra_Cell3 represents the reference battery impedance during the charging process of the third battery cell; F represents the impedance correction factor.

[0084] It should be noted that when the battery is in the discharge process, equations (1) to (3) can be rewritten as:

[0085] R_Cell1=ChgRa_Cell1×F; (1)

[0086] R_Cell2=ChgRa_Cell2×F; (2)

[0087] R_Cell3=ChgRa_Cell3×F. (3)

[0088] In the above formula, ChgRa_Cell1 represents the reference battery impedance during the discharge process of the first battery cell; ChgRa_Cell2 represents the reference battery impedance during the discharge process of the second battery cell; ChgRa_Cell3 represents the reference battery impedance during the discharge process of the third battery cell.

[0089] S302: Obtaining a voltage increment based on the actual battery impedance and the current threshold.

[0090] Specifically, according to Ohm's law, resistance multiplied by current equals voltage, so after obtaining the true battery impedance, the voltage increment is obtained by multiplying the true battery impedance by the current threshold. The voltage increment is used to determine whether the interference current in the battery charging and discharging circuit will affect the battery.

[0091] Continuing with the example of a battery with three cells, after obtaining the real battery impedance of the three cells, the calculation formula for the voltage increment of the three cells is:

[0092] ΔV_Cell1=R_Cell1×I s ; (4)

[0093] ΔV_Cell2=R_Cell2×I s ; (5)

[0094] ΔV_Cell3=R_Cell3×I s ; (6)

[0095] 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 Indicates the current threshold.

[0096] 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 a preset condition, controlling the battery charge and discharge circuit to disconnect from the battery.

[0097] Specifically, it is first necessary to determine whether the interference current is greater than the current threshold. The current threshold is determined by the full charge capacity of the battery. Usually, the current threshold is one tenth to one fifth of the full charge capacity of the battery. For example, when the full charge capacity of a battery is 4000mAh, the current threshold of the battery is 400mA to 800mA. When the interference current is much smaller than the current threshold, such as the current threshold is 400mA and the interference current is 120mA, the interference current has little impact on the normal use of the battery and the electrical equipment. When the interference current is close to or greater than the current threshold, the interference current has a more obvious impact on the normal use of the battery and the electrical equipment. Therefore, it is necessary to judge the battery voltage after the interference current appears, and determine whether the interference current will affect the battery and the electrical equipment by combining the size of the interference current and the size of the battery voltage. If there is an impact, the battery will be permanently disabled to avoid damage to the battery or the electrical equipment.

[0098] In the embodiment of the present application, after determining that the interference current is greater than the current threshold, it is also necessary to continuously monitor the interference current to determine whether the interference current will continue to exist, so as to avoid some interference currents that appear briefly and disappear and cause the electric meter to misjudge. When the duration of the interference current in the battery charge and discharge circuit is greater than the duration threshold, it means that the interference current has a continuous impact on the battery charge and discharge circuit. Among them, the value range of the duration threshold is 8~12s, and the values ​​that can be selected include but are not limited to: 8.0s, 8.2s, 8.5s, 8.8s, 9.0s, 9.2s, 9.5s, 9.8s, 10.0s, 10.2s, 10.5s, 10.8s, 11.0s, 11.2s, 11.5s, 11.8s, 12.0s. By setting the duration threshold in the electric meter, the duration of the interference current can be effectively judged, thereby avoiding misjudgment of the interference current.

[0099] In an embodiment of the present application, after determining 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. Wherein, the preset condition is configured to characterize the magnitude 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 appears, and the second voltage is the battery voltage after the interference current appears. Before the interference current appears, the battery voltage has been in a stable state. When the interference current appears, a voltage surge will occur in the battery charge and discharge 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 used 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 means that the voltage surge caused by the interference current will have 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 means 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.

[0100] Continuing with the example of a battery with three cells, the formula for comparing the first voltage, voltage increment and second voltage of the three cells is:

[0101] V0_Cell1+ΔV_Cell1<V1_Cell1; (7)

[0102] V0_Cell2+ΔV_Cell2<V1_Cell2; (8)

[0103] V0_Cell3+ΔV_Cell3<V1_Cell3; (9)

[0104] 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 Indicates the current threshold.

[0105] like Figure 3As shown, the embodiment of the present application also provides a battery protection device for protecting a battery in a battery charging and discharging circuit, wherein the battery charging and discharging circuit also includes a battery protection unit connected to the battery; the device includes: a current monitoring module, the current monitoring module is configured to determine that there is an interference current in the battery charging and discharging circuit when the battery protection unit is turned off. Specifically, the current monitoring module includes a fuel meter, an ammeter, a current sensor and other components or circuits capable of monitoring current. A voltage monitoring module, the voltage monitoring module is 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 includes a fuel meter, a voltmeter, a voltage sensor and other components or circuits capable of monitoring voltage. An operation module, the operation module is configured to determine the voltage increment of the battery based on a preset current threshold. Specifically, the operation module includes a fuel meter and a logic operation circuit and other components or circuits capable of calculating the voltage increment through data such as the current threshold. A control module, the control module is configured to respond 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 conditions, and permanently fail the battery. Specifically, the control module includes a fuel meter, a control chip, a control circuit, and other chips, components, or circuits that can compare, judge, and send control signals to the first voltage, the second voltage, and the voltage increment. The embodiment of the present application connects a battery protection device between the battery and the electrical equipment. When the protection unit of the battery is turned off, the interference current in the battery charge and discharge circuit can be monitored through the current monitoring module, and the voltage change in the battery charge and discharge circuit can be monitored through the voltage monitoring module. When the control module determines that the voltage after the interference current appears reaches a certain level and will cause damage to the battery, the battery is protected by controlling the battery to fail permanently.

[0106] like Figure 4As shown, the embodiment of the present application also provides a battery charging and discharging circuit, including: a battery S; a battery protection unit, the battery protection unit includes a first protection switch Q1 and a second protection switch Q2, the first protection switch Q1 and the second protection switch Q2 are connected in series and connected to the battery S; an electric meter, the electric meter is connected to the battery S, the first protection switch Q1 and the second protection switch Q2; a fuse unit F1, the fuse unit F1 is connected between the battery S and the battery protection unit, and the control end of the fuse unit F1 is connected to the electric meter; wherein the electric meter is configured to control the fuse unit F1 to fuse using any of the battery protection methods described above to protect the battery. Specifically, the battery charging and discharging circuit also includes 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, including 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 the first interface P+ and the second interface P- are used to connect electrical equipment. Among them, the positive electrode of the battery is connected to the first end of the fuse unit F1, the second end of the fuse unit F1 is connected to the input end of the first protection switch Q1 (the source of the MOS tube), the output end of the first protection switch Q1 (the drain of the MOS tube) is connected to the output end of the second protection switch Q2, the input end of the second protection switch Q2 is the first interface P+, ​​the control end of the first protection switch Q1 (the gate of the MOS tube) is connected to the CHG pin of the fuel meter, the control end of the second protection switch Q2 is connected to the DSG pin of the fuel meter, the input end of the third protection switch Q3 is connected to the negative electrode of the battery, the output end of the third protection switch Q3 is connected to the fuse control end of the fuse unit F1, and the control end of the third protection switch Q3 is connected to the FUSE pin of the fuel meter. The VC1 pin and VC2 pin of the fuel meter are connected to the positive end of the battery cell in the battery, and are used to obtain the voltage of each battery cell. The two ends of the precision resistor RS1 are respectively connected to the SRP pin and SRN pin of the fuel meter, and are used to obtain the current in the battery charging and discharging circuit. When general protection occurs in the battery charging and discharging circuit, that is, when the first protection switch Q1 or the second protection switch Q2 is turned off, the fuel meter will monitor the current in the battery charging circuit or the discharging circuit. When the fuel meter detects interference current, it determines whether the interference current will cause damage to the battery or electrical equipment by judging the size of the interference current, the duration of the interference current, and the voltage difference before and after the interference current appears. When the fuel meter determines that the voltage after the interference current appears reaches a certain level and will cause damage to the battery, the fuel meter controls the third protection switch Q3 to turn on to fuse the fuse unit F1 to permanently fail the battery, thereby protecting the battery.

[0107] The above is a detailed introduction to a battery protection method, device and charging and discharging circuit provided in the embodiments of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of ​​the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery protection method, characterized in that: Used to protect a battery in a battery charging and discharging circuit, wherein the battery charging and discharging circuit further includes a battery protection unit connected to the battery; the method includes: Determining that interference current exists in the battery charging and discharging circuit when the battery protection unit is turned off; Acquire 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, the method comprising: determining the actual battery impedance before the interfering current appears; obtaining the voltage increment based on the real battery impedance and the current threshold; The method of determining the real battery impedance before the interfering current appears includes: Obtaining the remaining capacity of the battery before the interference current occurs; Obtaining the real battery impedance based on the remaining battery capacity; 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, the fuel gauge in the battery charge and discharge circuit controls a fuse unit connected to the battery to fuse to permanently disable the battery, so that the battery charge and discharge circuit is disconnected from the battery; The preset condition includes that the sum of the first voltage and the voltage increment is less than the second voltage.

2. The battery protection method according to claim 1, characterized in that: Before obtaining the real battery impedance based on the remaining battery capacity, the method further includes: Acquiring the battery temperature before the interference current appears; An impedance correction factor for the battery is determined based on the battery temperature.

3. The battery protection method according to claim 2, characterized in that: The method for obtaining the real battery impedance based on the remaining battery capacity includes: 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 the product of the reference battery impedance and the impedance correction coefficient; 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 of the battery.

4. The battery protection method according to claim 3, characterized in that: The method for determining the impedance correction coefficient of the battery based on the battery temperature includes: Determining an impedance correction coefficient corresponding to the battery temperature based on a second mapping relationship of the battery; The second mapping relationship is characterized as a correspondence between different battery temperatures and impedance correction coefficients, and the correction coefficient is characterized by correcting the reference battery impedance to obtain the real battery impedance.

5. The battery protection method according to claim 1, characterized in that: Before controlling the battery charging and discharging circuit to disconnect from the battery, the method further includes: It is determined that the duration of the interference current is greater than a duration threshold.

6. A battery protection device, characterized in that: A battery protection method according to any one of claims 1 to 5 is used to protect a battery in a battery charging and discharging circuit, wherein the battery charging and discharging circuit further includes a battery protection unit connected to the battery; the device includes: a current monitoring module, the current monitoring module being configured to determine whether interference current exists in the battery charging and discharging circuit when the battery protection unit is turned off; A voltage monitoring module, wherein the voltage monitoring module is 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; A calculation module, wherein the calculation module is configured to determine a voltage increment of the battery based on a preset current threshold; A control module is configured to control the battery charge and discharge circuit to disconnect from the battery 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.

7. A battery charging and discharging circuit, characterized in that: include: Battery; A battery protection unit, wherein the battery protection unit is connected to the battery; A fuel gauge, the fuel gauge is connected to the battery and the battery protection unit respectively; A fuse unit, the fuse unit is connected between the battery and the battery protection unit, and a control end of the fuse unit is connected to the electricity meter; The fuel gauge is configured to control the fuse unit to fuse using the battery protection method according to any one of claims 1 to 5, so as to protect the battery.

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