Battery protection method, circuit and battery

Abstract

The embodiment of the invention provides a battery protection method, a circuit and a battery. The battery protection method comprises the following steps: acquiring the current temperature of a detection element in the battery protection circuit; wherein the detection element is a copper foil which meets battery protection conditions and has a preset size; the controller is connected with a positive electrode of a battery cell of the battery, and the detection element is respectively connected with a negative electrode of the battery cell and the controller; determining a current resistance value of the detection element based on the current temperature; and determining state information of the battery based on the current resistance value.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of battery protection, and relate to but are not limited to a battery protection method, circuit, and battery. Background Art

[0002] With the development of technology, batteries have been used for more than 20 years. In order to ensure that the battery can work safely and stably, a safety protection circuit needs to be configured on each battery. Among them, the battery's overcurrent protection and short circuit protection functions need to be completed through the linkage of the protection chip (IC, Integrated Circuit) and the precision resistor. Once the protection IC detects the threshold voltage or threshold current, it executes the protection action and disconnects the charge and discharge switch.

[0003] In order to achieve multi-level protection of the battery, one battery will use 2 to 4 precision resistors, but precision resistors are expensive and easily damaged by external forces. Therefore, how to reduce battery costs and reduce the impact of external forces on resistors while achieving battery protection is an urgent problem to be solved. Summary of the invention

[0004] In order to solve the problems existing in the related art, the embodiments of the present application provide a battery protection method, circuit and battery.

[0005] In a first aspect, the present application provides a battery protection method, which is applied to a controller of a battery protection circuit in a battery, and the method comprises:

[0006] Obtaining the current temperature of the detection element in the battery protection circuit; wherein the detection element is a copper foil that meets the battery protection conditions and has a preset size; the controller is connected to the positive electrode of the battery cell, and the detection element is respectively connected to the negative electrode of the battery cell and the controller;

[0007] Based on the current temperature, determining a current resistance value of the detection element;

[0008] Based on the current resistance value, state information of the battery is determined.

[0009] In some embodiments, the copper foil is a grounding copper foil of the battery protection circuit, the detection element comprises a first end and a second end, and the first end and the second end are taken from two points spaced apart on the copper foil;

[0010] The battery protection method further includes:

[0011] Detecting a detection voltage between two points of the copper foil;

[0012] Correspondingly, determining the state information of the battery based on the current resistance value includes:

[0013] The state information of the battery is determined based on the detected voltage between two points of the copper foil and the current resistance value.

[0014] In some embodiments, the controller stores a reference resistance value of the detection element and temperature drift coefficients corresponding to multiple temperatures; the current resistance value includes a current first resistance value and a current second resistance value;

[0015] The battery protection method further includes:

[0016] Based on the first strategy or the second strategy, determining the state information of the battery, the state information including first state information and second state information; the first state information is different from the second state information;

[0017] Among them, the first strategy includes determining the first state information based on the reference resistance value stored in the controller as the current first resistance value of the detection element; the second strategy includes determining the current second resistance value of the detection element based on the temperature drift coefficient of the current temperature and the reference resistance value to determine the second state information.

[0018] In some embodiments, the first strategy includes:

[0019] Obtaining a detection voltage across the detection element;

[0020] Calculating a first detection current of the battery corresponding to the current temperature based on the detection voltage and the current first resistance value;

[0021] In response to the first detection current being greater than or equal to the battery overcurrent value of the battery, the control switch of the battery protection circuit is disconnected to cut off the power circuit of the battery.

[0022] In some embodiments, the second strategy includes:

[0023] Obtaining a detection voltage across the detection element;

[0024] Calculating a current battery current of the battery at a current moment corresponding to the current temperature based on the detection voltage and the current second resistance value;

[0025] Based on the current battery current and the battery current at multiple moments before the current moment, second state information of the battery is determined, and the second state information at least includes current power information of the battery. In a second aspect, the present application provides a battery protection circuit, the battery protection circuit comprising:

[0026] A controller is connected to the positive electrode of the battery cell and the detection element respectively;

[0027] The detection element is connected to the negative electrode of the battery cell, and the detection element is a copper foil that meets the battery protection conditions and has a preset size;

[0028] The controller is used to obtain the current temperature of the detection element in the battery protection circuit; determine the resistance value of the detection element based on the current temperature; and determine the status information of the battery based on the current resistance value.

[0029] In some embodiments, the copper foil is a ground copper foil of the battery protection circuit, the detection element comprises a first end and a second end, and the first end and the second end are taken from two spaced points on the copper foil;

[0030] The controller is further used to detect a detection voltage between two points of the copper foil; and determine the state information of the battery based on the detection voltage between the two points of the copper foil and the current resistance value.

[0031] In some embodiments, the controller is further used to store a reference resistance value of the detection element and temperature drift coefficients corresponding to multiple temperatures;

[0032] The controller is further used to determine the state information of the battery based on the first strategy or the second strategy, the state information including first state information and second state information; the first state information is different from the second state information;

[0033] Among them, the first strategy includes determining the first state information of the battery based on the reference resistance value as the current first resistance value of the detection element; the second strategy includes determining the current second resistance value of the detection element based on the temperature drift coefficient of the current temperature and the reference resistance value to determine the second state information of the battery.

[0034] In some embodiments, the battery protection circuit includes a primary protection circuit and a secondary protection circuit connected in parallel, wherein:

[0035] The primary protection circuit includes a primary controller, a primary control switch and a primary detection element;

[0036] The secondary protection circuit includes a secondary controller, a secondary control switch and a secondary detection element;

[0037] The length of the primary detection element is obtained based on the primary protection current of the primary protection circuit, and the length of the secondary detection element is obtained based on the secondary protection current of the secondary protection circuit; the length of the primary detection element is different from the length of the secondary detection element.

[0038] In a third aspect, the present application provides a battery, comprising:

[0039] Battery cells;

[0040] A battery protection circuit, the battery protection circuit comprising:

[0041] A controller is connected to the positive electrode of the battery cell and the detection element respectively;

[0042] The detection element is connected to the negative electrode of the battery cell, and the detection element is a copper foil that meets the battery protection conditions and has a preset size;

[0043] The controller is used to obtain the current temperature of the detection element in the battery protection circuit; determine the resistance value of the detection element based on the current temperature; and determine the status information of the battery based on the current resistance value.

[0044] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The circuit structure of the battery protection circuit provided in the embodiment of the present application is shown in FIG. Figure 1 ;

[0046] Figure 2 The circuit structure of the battery protection circuit provided in the embodiment of the present application is shown in FIG. Figure 2 ;

[0047] Figure 3 This is an optional process diagram of the battery protection method provided in the embodiment of the present application. Figure 1 ;

[0048] Figure 4 This is an optional process diagram of the battery protection method provided in the embodiment of the present application. Figure 2 ;

[0049] Figure 5 This is an optional process diagram of the battery protection method provided in the embodiment of the present application. Figure 3 ;

[0050] Figure 6 1 is a schematic diagram of a circuit structure of a battery protection circuit using copper foil provided in an embodiment of the present application;

[0051] Figure 7 It is a schematic diagram of the test results of the copper foil provided in the embodiment of the present application at different temperatures;

[0052] Figure 8 It is a schematic diagram showing the change of the resistance of the copper foil provided in the embodiment of the present application with the temperature;

[0053] Fig. 9 It is a schematic diagram of the operation logic of the copper foil provided in the embodiment of the present application as a precision resistor;

[0054] Fig.10 It is a schematic diagram of the change in resistance of the copper foil with deformation provided in an embodiment of the present application. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. The described embodiments should not be regarded as limiting the present application. All other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0056] In the following description, reference is made to "some embodiments", which describe a subset of all possible embodiments, but it is understood that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict. Unless otherwise defined, all technical and scientific terms used in the embodiments of the present application have the same meaning as those commonly understood by those skilled in the art of the technical field of the embodiments of the present application. The terms used in the embodiments of the present application are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0057] In the related technology, in order to ensure that the battery can work safely and stably, a safety protection circuit needs to be configured on each battery. Among them, the battery's overcurrent protection and short-circuit protection functions need to be completed through the linkage of the protection IC and the precision resistor. Once the IC detects the threshold voltage, it executes the protection action and disconnects the charge and discharge switch. For example, if the overcurrent detection voltage of the protection IC is 20 millivolts (mV) and is matched with a 1 milliohm (mΩ) precision resistor, the overcurrent protection current of the battery is 20A. When the current current of the battery exceeds 20A, the overcurrent protection is executed.

[0058] Here, precision resistors generally refer to resistors with high precision (for example, the deviation between the actual resistance value of the resistor and its nominal resistance value is more than one ten-thousandth), low temperature drift (for example, the temperature coefficient is less than 10ppm, that is, the parameter change of the precision resistor is one millionth for every degree Celsius temperature change) and long-term stability (for example, the annual change rate is less than 50ppm). In order to ensure the accuracy and stability of the battery overcurrent value, the error of the precision resistor should be as small as possible.

[0059] However, the precision resistors used in the battery protection circuit in the related art are expensive and are prone to delamination after being impacted or bent. For example, when cutting a printed circuit board (PCB), it is easy to be damaged by external impact or by the bending and shearing force of the PCB during the manufacturing process.

[0060] Based on the problems existing in the related art, the embodiment of the present application reuses the copper foil on the circuit board as a precision resistor, which can not only effectively and stably detect battery overcurrent and short circuit conditions, but also effectively reduce the design cost. For example, a section of copper foil can be set in the negative electrode loop of the battery as a precision resistor.

[0061] In this way, the process cost is reduced by reusing the copper foil on the circuit board as a precision resistor; at the same time, the precision resistors are reduced, and the battery circuit has one less resistor component, which makes the resistance value of the battery circuit smaller and reduces heat loss.

[0062] Therefore, an embodiment of the present application provides a battery protection circuit. Figure 1 The circuit structure of the battery protection circuit provided in the embodiment of the present application is shown in FIG. Figure 1 ,like Figure 1 As shown, the battery protection circuit includes a controller 101 and a detection element 102. The controller 101 is connected to the positive electrode of the battery cell and the detection element 102 respectively; the detection element 102 is connected to the negative electrode of the battery cell; the controller 101 is used to obtain the current temperature of the detection element 102 in the battery protection circuit; based on the current temperature, determine the resistance value of the detection element 102; based on the current resistance value, determine the battery status information.

[0063] like Figure 1 As shown, the negative electrode circuit of the battery protection circuit is also provided with a charging switch and a discharging switch in series. The switch may be a metal oxide semiconductor (MOS) tube. As long as the charging protection or the discharging protection is triggered, the corresponding switch will be disconnected. Here, Figure 1 The two switches connected in series in the circuit will disconnect the battery charge and discharge circuit to protect the battery. Figure 1 The charging switch and discharging switch in the embodiment can be left-charging and right-discharging, or left-discharging and right-charging, which is not limited in the embodiment of the present application.

[0064] In some embodiments, the controller 101 may include one or more processing cores. The controller uses various interfaces and lines to connect various parts of the entire battery protection circuit (here, the controller can be connected to the detection elements and switches in the battery protection circuit through various pins), and executes various functions of the battery protection circuit by running or executing instructions, programs, code sets or instruction sets stored in the memory, and calling data stored in the memory.

[0065] In some embodiments, the controller may be implemented in at least one of a digital signal processing (DSP), a field programmable gate array (FPGA), and a programmable logic array (PLA). The controller may integrate one or a combination of a central processing unit (CPU), a graphics processing unit (GPU), and a modem.

[0066] The controller provided in the embodiment of the present application may have a storage function, that is, the controller may include a memory, and the memory may include a random access memory (Random Access Memory, RAM), and may also include a read-only memory (Read-Only Memory). Here, the memory includes a non-transitory computer-readable storage medium. The memory can be used to store instructions, programs, codes, code sets, or instruction sets. The memory may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function (such as overcurrent detection, etc.), instructions for implementing the following various method embodiments, etc.

[0067] In some embodiments, the detection element 102 is a copper foil having a preset size that meets the battery protection conditions. Here, meeting the battery protection conditions may mean being able to achieve current detection (e.g., real-time monitoring and protection of abnormal conditions such as battery overcurrent and short circuit) and protection functions that can be achieved by precision resistors (e.g., in abnormal conditions such as overcharging, overdischarging, and short circuit, the current change detected by the detection element can trigger a protection mechanism to cut off the current in time and prevent battery damage).

[0068] In the embodiment of the present application, the overcurrent value of each battery is different, and the preset size of the copper foil in the battery is different. For example, the preset size is Figure 1 The length between AB.

[0069] When designing the protection circuit of each battery, the length of the detection element in the negative electrode loop, i.e., the preset size, can be obtained based on the overcurrent value of the battery, the resistivity, resistance value and cross-sectional area of ​​the detection element (based on the design of the circuit board, the cross-sectional area of ​​different battery detection elements is known). The preset size can be achieved by formula (1):

[0070] R = ρ(T) × L / A (1);

[0071] Where R is the resistance of the sensing element, ρ(T) is the resistivity of the sensing element (Ω·m), L is the length of the sensing element (m), and A is the cross-sectional area of ​​the resistor (m 2 ).

[0072] In the embodiment of the present application, the copper foil is a grounding copper foil of a multiplexed battery protection circuit. The detection element 102 includes a first end A and a second end B. The first end A and the second end B are taken from two points spaced apart on the copper foil, that is, the complete length of the copper foil in the battery protection circuit is greater than or equal to the length between AB. After determining the overcurrent value of the battery, the length between AB is determined by formula (1), and the AB point is determined in the copper foil, and the AB point is connected to the pin of the controller. The pin can be a VBAT pin for voltage detection; it can be a CS pin for current monitoring; it can be a THM pin for temperature monitoring; it can also be a PROG pin for charging state detection.

[0073] In some embodiments, the controller 101 is further used to detect a detection voltage between two points of the copper foil, and determine battery status information, such as power level, based on the detection voltage between the two points of the copper foil and a current resistance value.

[0074] Figure 1 The battery protection circuit in the circuit is a primary protection circuit. For batteries with complex use environments, multi-level protection is required. Figure 2 The circuit structure of the battery protection circuit provided in the embodiment of the present application is shown in FIG. Figure 2 ,like Figure 2 As shown, the battery protection circuit includes a primary protection circuit and a secondary protection circuit connected in parallel, wherein the primary protection circuit includes a primary controller 201, a primary control switch 202 and a primary detection element 203; the secondary protection circuit includes a secondary controller 204, a secondary control switch 205 and a secondary detection element 206. The length of the primary detection element 203 is obtained based on the primary protection current of the primary protection circuit, and the length of the secondary detection element 206 is obtained based on the secondary protection current of the secondary protection circuit. Here, since the primary protection current is different from the secondary protection current, the length of the primary detection element is different from the length of the secondary detection element. The primary protection current is less than the secondary protection current.

[0075] Here, the primary protection circuit realizes the primary protection of the battery, and the secondary protection circuit realizes the secondary protection of the battery. The primary control switch 202 is connected in series with the secondary control switch 205, so that no matter whether the primary protection or the secondary protection is triggered, the battery charging and discharging circuit will be disconnected.

[0076] The primary controller 201 and the secondary controller 204 may be the same or different protection ICs, which are used to perform primary protection and secondary protection of the battery respectively. The battery protection methods corresponding to the primary protection and the secondary protection can be implemented by the battery protection method provided in the embodiment of the present application.

[0077] It should be noted that the description of the battery protection circuit in the embodiment of the present application is similar to the description of the battery protection method described below, and has similar beneficial effects as the battery protection method, which will be described in detail in the following embodiments, so it will not be repeated here. For technical details not disclosed in the embodiments, please refer to the description of the battery protection method of the present application for understanding.

[0078] The embodiment of the present application can also provide a battery, which includes a battery cell and a battery protection circuit. The battery protection circuit includes a controller and a detection element, the controller is connected to the positive electrode of the battery cell and the detection element respectively, the detection element is connected to the negative electrode of the battery cell, and the detection element is a copper foil that meets the battery protection conditions and has a preset size; the controller is used to obtain the current temperature of the detection element in the battery protection circuit; based on the current temperature, determine the resistance value of the detection element; based on the current resistance value, determine the status information of the battery.

[0079] The technical solution of the present application will be described in detail below with reference to the accompanying drawings.

[0080] Figure 3 This is an optional process diagram of the battery protection method provided in the embodiment of the present application. Figure 1 The execution subject of the battery protection method provided in the embodiment of the present application is a controller of a battery protection circuit (such as a protection IC), such as Figure 3 As shown, the battery protection method provided in the embodiment of the present application can be implemented through steps S301 to S302:

[0081] Step S301, obtaining the current temperature of the detection element in the battery protection circuit; wherein the detection element is a copper foil that meets the battery protection conditions and has a preset size; the controller is connected to the positive electrode of the battery cell, and the detection element is respectively connected to the negative electrode of the battery cell and the controller.

[0082] In an embodiment of the present application, a temperature sensor may be integrated inside the battery, and the controller may be connected to the sensor via a pin to obtain the temperature of the detection element based on the temperature sensor.

[0083] In the embodiment of the present application, the detection element is a copper foil that meets the battery protection conditions and has a preset size. Here, meeting the battery protection conditions can mean being able to achieve current detection (such as real-time monitoring and protection of abnormal conditions such as battery overcurrent and short circuit) and protection functions that can be achieved by precision resistors (for example, in abnormal conditions such as overcharging, overdischarging, and short circuit, the current change detected by the detection element can trigger the protection mechanism, cut off the current in time, and prevent battery damage).

[0084] like Figure 1 As shown, the controller is connected to the positive electrode of the battery cell, and the detection element is connected to the negative electrode of the battery cell and the controller respectively. The specific connection method is not repeated here.

[0085] Step S302: Determine the current resistance value of the detection element based on the current temperature.

[0086] In the embodiment of the present application, the copper foil is greatly affected by the charging current and the ambient temperature, and its resistance will increase at high temperatures, that is, the resistance of the copper foil will change with changes in temperature. Therefore, for situations with high detection accuracy requirements such as overcurrent detection, the embodiment of the present application needs to use temperature to determine the current resistance value of the detection element at the current temperature.

[0087] In the embodiment of the present application, a section of copper foil can be selected, and the resistance of the section of copper foil at different temperatures can be tested to obtain a temperature-impedance table of the copper foil at different temperatures. Based on the temperature-impedance table, a linear relationship between the temperature and impedance of the copper foil can be determined. Based on the linear relationship, the resistance of the detection element at any temperature can be determined, that is, the current resistance value of the detection element at the current temperature can be determined. Here, the slope of the linear relationship is the temperature drift coefficient of the copper foil.

[0088] In some embodiments, after the temperature-impedance table is determined, a straight line can be fitted based on the temperature-impedance table to obtain a slope of temperature and impedance, and the slope of the slope is used as the temperature drift coefficient of the copper foil.

[0089] In some embodiments, after obtaining the linear relationship, the error of the linear relationship (i.e., slope) between temperature and resistance value can be minimized by matrix multiplication, least squares method, etc., that is, the error between the actual relationship between temperature and resistance value and the fitted linear relationship is minimized.

[0090] In the embodiment of the present application, after the linear relationship between temperature and resistance is determined, the linear relationship (i.e., the temperature drift coefficient of the copper foil) can be burned into the controller through firmware, so that after the controller obtains the current temperature of the copper foil, it can determine the current resistance value of the detection element based on the current temperature. Here, the controller can be integrated with a gas gauge, and the linear relationship can also be burned into the gas gauge through firmware.

[0091] In an embodiment of the present application, the resistance value of the copper foil at a standard temperature (for example, 25°C) can be determined as the reference resistance value of the copper foil, and the reference resistance value can be burned into the controller. After determining the current temperature, the current resistance value can be calculated based on the temperature drift coefficient and the resistance value at the standard temperature.

[0092] In some embodiments, the current resistance value R(T) at the current temperature T can be realized by formula (2):

[0093] R(T)=R 0 [1+α(TT 0 )] (2);

[0094] Where R(T) represents the resistance of the copper foil at temperature T, R 0 represents the copper foil resistance at a reference temperature of 25°C, and α represents the temperature drift coefficient of the copper foil. 0 and R 0 It is known that the current resistance value R(T) at the current temperature T can be determined through the temperature drift coefficient and the current temperature.

[0095] Step S303: Determine the battery status information based on the current resistance value.

[0096] In the embodiment of the present application, the battery status information may include information such as the battery power and current current value. For example, after determining the current resistance value of the detection element at the current temperature, the current flowing through the battery can be obtained by calculating I=U / R, and this information is counted in the protection IC, and the power can be accurately calculated using the Coulomb integration method.

[0097] The embodiment of the present application reuses the copper foil in the circuit as a precision resistor, takes into account the influence of temperature on the test accuracy, and can effectively and accurately realize the battery protection function of the precision resistor; the copper foil detection element supported by the PCB will not produce stratification after impact or bending, which improves the reliability of the detection element and greatly reduces the cost; at the same time, it can reduce the weight of the battery and optimize the layout space of the battery protection circuit; and the copper foil can be applied to lithium batteries, solid-state batteries, sodium-ion batteries and other power batteries of different specifications and systems, has strong compatibility, and expands the application scenarios.

[0098] based on Figure 1 The copper foil is a grounding copper foil of the battery protection circuit, and the detection element includes a first end A and a second end B, and the first end A and the second end B are taken from two points spaced apart on the copper foil. The battery protection method provided in the embodiment of the present application may also include step S1:

[0099] Step S1, detecting the detection voltage between two points of the copper foil.

[0100] In the embodiment of the present application, the detection voltage between two points of the copper foil can be realized by a voltage detection circuit connecting the two points of the copper foil, and the voltage difference between the two points of the copper foil is determined as the detection voltage between the two points of the copper foil.

[0101] Correspondingly, step S303 can be implemented by step S3031:

[0102] Step S3031: Determine the status information of the battery based on the detection voltage between the two points of the copper foil and the current resistance value.

[0103] In the embodiment of the present application, after determining the detection voltage and current resistance value between two points of the copper foil, the current flowing through the battery can be obtained by calculating I=U / R. This information is counted in the protection IC, and the power can be accurately calculated using the Coulomb integration method.

[0104] In some embodiments, the controller stores a reference resistance value of the detection element and a temperature drift coefficient corresponding to multiple temperatures. The temperature drift coefficient is used to characterize the rate of change of the resistance value of the detection element with temperature change. Here, the temperature drift coefficient is the slope of the linear relationship between the copper foil temperature and the resistance value. The current resistance value of the detection element includes the current first resistance value and the current second resistance value. Correspondingly, the battery protection method provided in the embodiment of the present application may also include step S2:

[0105] Step S2, based on the first strategy or the second strategy, determine the status information of the battery, the status information including first status information and second status information; the first status information is different from the second status information; wherein the first strategy includes determining the first status information based on the reference resistance value stored in the controller as the current first resistance value of the detection element; the second strategy includes determining the current second resistance value of the detection element based on the temperature drift coefficient of the current temperature and the reference resistance value to determine the second status information.

[0106] Here, the first status information may be whether the battery is currently overcurrented, and the second status information may be the current power level of the battery.

[0107] In some embodiments, the temperature rise of the copper foil may be due to the high ambient temperature or the large charging current. If the temperature of the copper foil is currently high due to the charging current (for example, the temperature of the copper foil is significantly different from the ambient temperature), in order to stabilize the overcurrent value of the battery, the resistance value of the copper foil at a standard temperature (for example, 25°C) can be determined as the reference resistance value of the copper foil. Regardless of the current temperature, the current current value of the battery is calculated based on the reference resistance value, and the battery is judged based on the current value to determine whether it is overcurrent. If the temperature of the copper foil is currently high due to the high ambient temperature, it is necessary to determine the resistance value at the current temperature through the temperature drift coefficient and the resistance value at the standard temperature, calculate the current current value of the battery based on the calculated resistance value, and judge whether the battery is overcurrent based on the current value.

[0108] In some embodiments, during the charging and discharging process of the battery, the current value at the current temperature can be determined in real time, and the current value can be integrated in real time, so as to continuously calculate the remaining power (SOC, State of Charge) value of the battery.

[0109] The embodiment of the present application corrects the resistance value of the copper foil through the temperature drift coefficient, which can accurately complete the overcurrent protection function of the battery and accurately obtain the status information of the battery, thereby ensuring the safety of battery use.

[0110] In some embodiments, Figure 4 This is an optional process diagram of the battery protection method provided in the embodiment of the present application. Figure 2 ,like Figure 4 As shown, the first strategy can be implemented through steps S401 to S403:

[0111] Step S401: Obtain a detection voltage across the detection element.

[0112] In the embodiment of the present application, the detection voltage between two points of the copper foil can be realized by a voltage detection circuit connecting the two points of the copper foil, and the voltage difference between the two points of the copper foil is determined as the detection voltage between the two points of the copper foil.

[0113] Step S402: Calculate a first detection current of the battery corresponding to the current temperature based on the detection voltage and the current first resistance value.

[0114] In the embodiment of the present application, the first resistance value may be a reference resistance value at a reference temperature, or a resistance value at a current temperature calculated based on a temperature drift coefficient. If the temperature of the copper foil is high due to the charging current, the resistance value of the copper foil at a standard temperature (e.g., 25°C) is determined as the reference resistance value of the copper foil, and the first detection current of the battery is calculated based on the reference resistance value regardless of the current temperature; if the temperature of the copper foil is high due to a high ambient temperature, the first detection current at the current temperature needs to be determined by the temperature drift coefficient and the resistance value at the standard temperature.

[0115] After determining the detection voltage across the detection element and the first detection current, the first detection current flowing through the battery at the current temperature can be obtained by calculating I=U / R.

[0116] Step S403: in response to the first detection current being greater than or equal to the battery overcurrent value of the battery, disconnecting the control switch of the battery protection circuit to cut off the power circuit of the battery.

[0117] In the embodiment of the present application, the battery overcurrent value of the battery is known. When the battery has multiple levels of protection circuits, the battery overcurrent values ​​of each level of protection circuits are different.

[0118] After obtaining the first detection current of the battery, the first detection current can be compared with the battery overcurrent value of the battery. If the first detection current is greater than or equal to the battery overcurrent value of the battery, it means that the battery is in an overcurrent state. At this time, the control switch of the battery protection circuit is disconnected to cut off the battery's power circuit and realize the battery's overcurrent protection function.

[0119] In the embodiment of the present application, by reusing the ground copper foil in the protection circuit as a precision resistor, the influence of temperature on the test accuracy is taken into consideration, and the battery protection function of the precision resistor can be effectively and accurately realized while reducing costs.

[0120] In some embodiments, Figure 5 This is an optional process diagram of the battery protection method provided in the embodiment of the present application. Figure 3 ,like Figure 5 As shown, the second strategy can be implemented through steps S501 to S503:

[0121] Step S501: Obtain a detection voltage across the detection element.

[0122] Step S502: Calculate the current battery current of the battery at the current moment corresponding to the current temperature based on the detection voltage and the current second resistance value.

[0123] In the embodiment of the present application, the second resistance value is a resistance value at the current temperature determined by the temperature drift coefficient and the resistance value at the standard temperature. At this time, the current battery current of the battery at the current time corresponding to the current temperature can be calculated by detecting the voltage and the current second resistance value.

[0124] Step S503: Determine second status information of the battery based on the current battery current and the battery currents at multiple times before the current time, where the second status information at least includes current power information of the battery.

[0125] In the embodiment of the present application, the current battery current and the battery current at multiple times before the current moment can be integrated through Coulomb integration to obtain the remaining battery power.

[0126] The embodiment of the present application uses copper foil as a precision resistor to quickly respond to changes in battery current at different temperatures, thereby updating the SOC value in real time. For battery management systems that require rapid response, the accuracy of SOC prediction can be improved; this method is applicable to any type of battery, improving the applicable scenarios of the battery protection method.

[0127] It should be noted that the connection of the battery protection circuit in the battery protection method in the embodiment of the present application is similar to the description in the aforementioned circuit embodiment, and has similar beneficial effects as the battery protection method, so it will not be described in detail. For undisclosed technical details, please refer to the aforementioned description for understanding.

[0128] The present application embodiment proposes a battery preparation scheme using PCB copper foil as a precision resistor for protecting the circuit. A section of copper foil in the PCB printed circuit board wiring of the battery negative electrode loop can be taken, such as Figure 1 As shown, determine the positions of points A / B at both ends of the copper foil, apply a constant current to the battery, measure the voltage between A / B, and use Ohm's law to obtain the internal resistance between A / B. The copper foil with this value can be directly used as the precision resistance value.

[0129] This method can calibrate each battery on the battery production line to achieve an accuracy of one ten-thousandth. At the same time, the compensation coefficient of the copper foil temperature (i.e., the temperature drift coefficient) is recorded in the power meter to achieve accurate identification of the copper foil in the entire temperature range.

[0130] Figure 6 is a schematic diagram of the circuit structure of a battery protection circuit using copper foil provided in an embodiment of the present application, such as Figure 6 As shown, the battery protection circuit can realize primary protection and secondary protection of the battery. Figure 6As shown, the primary protection circuit includes a primary protection IC 601, a primary control switch 602, and a primary copper foil 603; the secondary protection circuit includes a secondary protection IC 602, a secondary control switch 605, and a secondary copper foil 606. The position of the copper foil on the PCB is shown in FIG. Figure 6 The primary protection IC here may be an integrated IC that integrates the protection IC and the fuel gauge function.

[0131] Figure 7 Schematic diagram of the test results of the copper foil at different temperatures provided in the embodiment of the present application. Figure 7 As shown, after testing the precision resistor (RS) and copper foil (COP) at the same temperature, it can be obtained that the copper foil overcurrent protection value meets the specification; the impedance consistency of different copper foil samples is good; the higher the temperature, the copper foil impedance (copper resistance) gradually increases, that is, the discharge overcurrent protection value (copper current) is lower, which meets the safety requirements of the battery cell under actual applications.

[0132] However, copper foil also has some inherent problems in practical applications. For example, copper foil is greatly affected by charging current and ambient temperature, and its resistance will increase at high temperatures. Figure 8 Schematic diagram showing the change of the resistance of the copper foil with temperature provided in the embodiment of the present application. Figure 8 As shown, from the impedance test of multiple samples (such as sample 1 to sample 5) at 0℃ to 65℃, it can be seen that the resistance value change rate of copper foil is as high as 20% when the temperature changes. For the scenario where the accuracy requirement is not high, such as the secondary protection of the battery, ordinary PCB copper foil can be directly used as a precision resistor. However, if the accuracy requirement for the primary protection circuit is very high, such as the scenario with an accuracy error of less than 1%, the impact of temperature on the solution must be considered. At this time, if the precision resistors of the entire battery protection circuit loop are replaced by copper foil, the resistance value of the copper foil must be accurately calculated based on the current temperature to realize the protection IC combined with copper foil to detect current and integrate and calculate power.

[0133] Therefore, in order to achieve accurate use in the entire temperature range, the temperature compensation coefficient (i.e., temperature drift coefficient) and the operation logic for copper foil resistance compensation based on the temperature drift coefficient need to be added to the protection IC, so as to achieve multi-level protection of the battery. First, the copper foil resistance of each battery at normal temperature (such as 25°C) is calculated on the production line (it can be done by applying a constant current, testing the voltage across the copper foil, and calculating the copper foil impedance of each independent battery), and this resistance value is fixedly recorded in the fuel gauge IC; secondly, through the calculation of I=U / R, a stable and accurate overcurrent value is obtained, and the battery protection function is realized.

[0134] The embodiment of the present application integrates a fuel meter with a primary protection IC and reuses PCB copper foil as a precision resistor, thereby meeting the requirements that each independent battery can accurately detect the battery current at all temperatures and realize the solution of accurately calculating the power by the fuel meter. Fig. 9 This is a schematic diagram of the operation logic of the copper foil as a precision resistor provided in the embodiment of the present application, such as Fig. 9 As shown, the operation logic can be implemented through steps S901 to S906:

[0135] Step S901, calculating the resistance value under the standard state.

[0136] In the embodiment of the present application, when the protection IC model is selected, the battery overcharge or over-discharge protection current detection voltage U can be obtained, and then the battery required protection current I can be obtained, which is a fixed value for each battery. Based on Ohm's law, the resistance value of the copper foil in the standard state (i.e., room temperature 25°C) can be obtained.

[0137] Step S902: Select copper foil points with corresponding resistance values.

[0138] Selecting a copper foil point of corresponding resistance value means selecting a section on the copper foil as a precision resistor, and connecting the two ends of the section to the protection IC.

[0139] In an embodiment of the present application, the resistance of the copper foil can be tested in a laboratory environment over the entire temperature range to obtain a temperature-resistance table of the copper foil. Linear algebra is performed based on the table to obtain the temperature drift coefficient of the copper foil and a linear relationship formula between temperature and resistance, and the temperature drift coefficient is burned into the power meter.

[0140] Step S903: confirm the current temperature.

[0141] The current temperature of the copper foil may be determined by a temperature sensor.

[0142] Step S904: Feedback the current temperature to the electricity meter.

[0143] Step S905: calculating the resistance value based on the temperature drift coefficient and the current temperature.

[0144] Here, the resistance value of the copper foil at the current temperature may be calculated by the method provided in the aforementioned embodiment.

[0145] Step S906, triggering the voltage threshold for protecting the IC from overcurrent detection.

[0146] In some embodiments, it can be determined whether the battery is overcurrent based on the current resistance value, thereby triggering the overcurrent protection of the battery. Alternatively, when the battery voltage reaches a set protection threshold, the protection IC will disconnect the charge and discharge switch to prevent the battery from overcharging or overdischarging.

[0147] The present application embodiment also tests the resistance of the copper foil and the corresponding discharge overcurrent value of three batteries under 0° / 3° / 6° / 9° deformation. Fig.10 Schematic diagram of the change in resistance of the copper foil with deformation provided in the embodiment of the present application, such as Fig.10 As shown in the figure, when the copper foil is deformed from 3° slightly to 9° severely, the overcurrent protection value of the copper foil changes by a maximum of 2.39%. The protection delay and resistance change are relatively stable. Compared with precision resistors, copper foil has strong deformation resistance and is more conducive to long-term and reliable use in battery protection circuits.

[0148] At the same time, in order to better ensure the safety of copper foil, some extreme tests in safety regulations are used for verification, including overcurrent loading, external terminal short circuit, cyclic overcurrent, cyclic short circuit test, etc., which all meet the situation that the abnormal protection circuit is activated every time. Based on the above verification results, the solution of using copper foil as precision resistor in the primary protection circuit and the secondary protection circuit in the embodiment of the present application is feasible.

[0149] The embodiment of the present application reduces the process cost by using copper foil as the precision resistor, so that the cost can be reduced by 3 to 4%; the precision resistor is reduced in the PC B board, and the battery protection circuit has one less resistor component, which makes the resistance of the circuit smaller and further reduces the heat loss; the embodiment of the present application takes into account the influence of temperature on the test accuracy, introduces the temperature drift coefficient and burns it into the power calculation method, which can effectively and accurately cooperate to complete the overcurrent protection function and optimize the layout space and weight; finally, the embodiment of the present application makes the precision resistor replaceable, without the need to manufacture precision resistors, reducing carbon emissions and meeting the design requirements of energy saving and low carbon.

[0150] The above is only an embodiment of the present application and is not intended to limit the protection scope of the present application. Any modifications, equivalent substitutions and improvements made within the spirit and scope of the present application are included in the protection scope of the present application.

[0151] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in various embodiments of the present application, the size of the sequence number of the above-mentioned processes does not mean the order of execution, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application. The above-mentioned sequence numbers of the embodiments of the present application are only for description and do not represent the advantages and disadvantages of the embodiments.

[0152] It should be noted that, in this article, the terms "comprises," "includes" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method or device. In the absence of further restrictions, an element defined by the statement "comprises one..." does not exclude the presence of other identical elements in the process, method, article or device including the element. In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored, or not executed.

[0153] The above is only an implementation method of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A battery protection method, applied to a controller of a battery protection circuit in a battery, the method comprising: Obtaining the current temperature of the detection element in the battery protection circuit; wherein the detection element is a copper foil that meets the battery protection conditions and has a preset size; the controller is connected to the positive electrode of the battery cell, and the detection element is respectively connected to the negative electrode of the battery cell and the controller; Based on the current temperature, determining a current resistance value of the detection element; Based on the current resistance value, state information of the battery is determined.

2. The battery protection method according to claim 1, wherein the copper foil is a grounding copper foil of the battery protection circuit, and the detection element comprises a first end and a second end, and the first end and the second end are taken from two points spaced apart on the copper foil; The battery protection method further includes: Detecting a detection voltage between two points of the copper foil; Correspondingly, determining the state information of the battery based on the current resistance value includes: The state information of the battery is determined based on the detected voltage between two points of the copper foil and the current resistance value.

3. The battery protection method according to claim 2, wherein the controller stores a reference resistance value of the detection element and temperature drift coefficients corresponding to multiple temperatures; the current resistance value includes a current first resistance value and a current second resistance value; The battery protection method further includes: Based on the first strategy or the second strategy, determining the state information of the battery, the state information including first state information and second state information; the first state information is different from the second state information; Among them, the first strategy includes determining the first state information based on the reference resistance value stored in the controller as the current first resistance value of the detection element; the second strategy includes determining the current second resistance value of the detection element based on the temperature drift coefficient of the current temperature and the reference resistance value to determine the second state information.

4. The battery protection method according to claim 3, wherein the first strategy comprises: Obtaining a detection voltage across the detection element; Calculating a first detection current of the battery corresponding to the current temperature based on the detection voltage and the current first resistance value; In response to the first detection current being greater than or equal to the battery overcurrent value of the battery, the control switch of the battery protection circuit is disconnected to cut off the power circuit of the battery.

5. The battery protection method according to claim 3, wherein the second strategy comprises: Obtaining a detection voltage across the detection element; Calculating a current battery current of the battery at a current moment corresponding to the current temperature based on the detection voltage and the current second resistance value; Based on the current battery current and the battery currents at multiple times before the current time, second status information of the battery is determined, where the second status information at least includes current power information of the battery.

6. A battery protection circuit, comprising: A controller is connected to the positive electrode of the battery cell and the detection element respectively; The detection element is connected to the negative electrode of the battery cell, and the detection element is a copper foil that meets the battery protection conditions and has a preset size; The controller is used to obtain the current temperature of the detection element in the battery protection circuit; Based on the current temperature, determining a resistance value of the detection element; Based on the current resistance value, state information of the battery is determined.

7. The battery protection circuit according to claim 6, wherein the copper foil is a ground copper foil of the battery protection circuit, the detection element comprises a first end and a second end, and the first end and the second end are taken from two spaced points on the copper foil; The controller is further used to detect a detection voltage between two points of the copper foil; and determine the state information of the battery based on the detection voltage between the two points of the copper foil and the current resistance value.

8. The battery protection circuit according to claim 7, wherein the controller is further used to store a reference resistance value of the detection element and temperature drift coefficients corresponding to multiple temperatures; The controller is further used to determine the state information of the battery based on the first strategy or the second strategy, the state information including first state information and second state information; the first state information is different from the second state information; in, The first strategy includes determining the first state information of the battery based on the reference resistance value as the current first resistance value of the detection element; the second strategy includes determining the current second resistance value of the detection element based on the temperature drift coefficient of the current temperature and the reference resistance value to determine the second state information of the battery.

9. The battery protection circuit according to any one of claims 6 to 8, comprising a primary protection circuit and a secondary protection circuit connected in parallel, wherein: The primary protection circuit includes a primary controller, a primary control switch and a primary detection element; The secondary protection circuit includes a secondary controller, a secondary control switch and a secondary detection element; The length of the primary detection element is obtained based on the primary protection current of the primary protection circuit, and the length of the secondary detection element is obtained based on the secondary protection current of the secondary protection circuit; the length of the primary detection element is different from the length of the secondary detection element.

10. A battery comprising: Battery cells; A battery protection circuit, the battery protection circuit comprising: A controller is connected to the positive electrode of the battery cell and the detection element respectively; The detection element is connected to the negative electrode of the battery cell, and the detection element is a copper foil that meets the battery protection conditions and has a preset size; The controller is used to obtain the current temperature of the detection element in the battery protection circuit; determine the resistance value of the detection element based on the current temperature; and determine the status information of the battery based on the current resistance value.

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