Equalization current sampling circuit, equalization circuit and battery management system

Abstract

The utility model relates to an equalizing current sampling circuit, an equalizing circuit and a battery management system. For a target battery cell of a to-be-sampled equalization current, the equalization current sampling circuit comprises an equalization module, a sampling module, an equalization resistor arranged in the equalization module, and a first sampling resistor connected in series with the equalization resistor. Wherein the equalization resistor is arranged between the target battery cell and the analog front end and is used for carrying out equalization operation on the target battery cell according to an equalization signal of the analog front end; the sampling module is connected with the first sampling resistor and the analog front end, and is used for collecting a first voltage value at the two ends of the first sampling resistor, so that the analog front end determines a first equalization current value of the target cell according to the first voltage value. According to the invention, the equalization current of the target cell can be obtained in real time, the equalization current obtaining precision is improved, and the SOC calculation precision can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of balanced current sampling, and in particular to a balanced current sampling circuit, a balanced circuit and a battery management system. Background Art

[0002] The structure of BMS (Battery Management System) can be mainly divided into centralized and distributed. Among them, the distributed, that is, the master-slave structure is the more commonly used system structure. In the master-slave structure, the slave board is the AFE (analog front end), each AFE is connected to a certain number of cells, used to collect the voltage and temperature of the cells, and send the collected data to the main control chip. As the capacity of the cells continues to increase, the balancing operation of the cell capacity is becoming more and more important to ensure the consistency of the cells.

[0003] In traditional battery balancing operations, an estimation method is used to obtain the balancing current. However, there is an error between the estimated theoretical balancing current and the actual balancing current, which will lead to inaccurate battery balancing capacity and increase the error of the calculated SOC (state of charge) of each battery cell. Utility Model Content

[0004] Based on this, it is necessary to provide a balancing current sampling circuit, balancing circuit and battery management system that can obtain precise current, so as to improve the accuracy of battery capacity balancing and thus improve the SOC calculation accuracy by obtaining accurate balancing current.

[0005] In a first aspect, the present application provides a balanced current sampling circuit, which is applied to balanced current sampling when each battery cell in a battery pack is balanced. The battery pack includes a plurality of batteries, each of which is connected to an analog front end. For a target battery cell to be sampled for balanced current, the balanced current sampling circuit includes:

[0006] A balancing module, the balancing module comprising a balancing resistor, the balancing resistor being arranged between the target cell and the analog front end, and being used for performing a balancing operation on the target cell according to a balancing signal of the analog front end;

[0007] A first sampling resistor is connected in series with the balancing resistor;

[0008] The sampling module is connected to the first sampling resistor and the analog front end respectively, and is used to collect a first voltage value across the first sampling resistor so that the analog front end determines a first balancing current value of the target battery cell according to the first voltage value.

[0009] In some embodiments, the analog front end includes a first analog front end and a second analog front end, wherein:

[0010] The first analog front end is used to connect to the equalization module to perform equalization operation on the target battery cell;

[0011] The second analog front end is used to connect to the sampling module to implement sampling of the first balancing current value of the target battery cell.

[0012] In some of the embodiments, the second analog front end may also be connected to sampling modules corresponding to other battery cells to collect voltage values ​​of other sampling resistors to obtain balanced current values ​​of other sampling resistors.

[0013] In some of the embodiments, the first analog front end and the second analog front end are both connected to a main control chip, and the first analog front end and the second analog front end are communicatively connected to the main control chip via a daisy chain.

[0014] In some embodiments, the balanced current sampling circuit further includes a common resistor, and the common resistor is connected to the balanced module to form a balanced loop.

[0015] In a second aspect, the present application provides a balancing circuit, including the balancing current sampling circuit proposed according to the first aspect.

[0016] In some embodiments, the equalization circuit further comprises:

[0017] External power supply;

[0018] A selection switch is selected, one end of which is connected to an external power source, and the other end of which is connected to each battery cell in the battery pack. The selection switch is used to conduct a connection path between the external power source and the target battery cell.

[0019] In some embodiments, the equalization circuit further comprises:

[0020] A second sampling resistor, one end of the second sampling resistor is connected to the external power supply, and the other end of the second sampling resistor is connected to the selection switch.

[0021] In some of the embodiments, the selection switch is also connected to the main control chip, and is used to conduct a connection path between the external power supply and the target battery cell according to a control instruction of the main control chip;

[0022] and / or;

[0023] The second sampling resistor is also connected to the main control chip, so that the main control chip determines the second balancing current value according to the voltage value at both ends of the second sampling resistor.

[0024] In a third aspect, the present application provides a battery management system, including a balancing current sampling circuit according to the first aspect or a balancing circuit according to the second aspect.

[0025] The above-mentioned balancing current sampling circuit is applied to the balancing current sampling when each battery cell in the battery pack is balanced. The battery pack includes a plurality of battery cells, each of which is connected to the analog front end. For the target battery cell whose balancing current is to be sampled, the balancing current sampling circuit includes a balancing module and a sampling module, a balancing resistor arranged in the balancing module, and a first sampling resistor connected in series with the balancing resistor. Among them, the balancing resistor is arranged between the target battery cell and the analog front end, and is used to perform a balancing operation on the target battery cell according to the balancing signal of the analog front end; the sampling module is respectively connected to the first sampling resistor and the analog front end, and is used to collect the first voltage value at both ends of the first sampling resistor, so that the analog front end determines the first balancing current value of the target battery cell according to the first voltage value. The balancing current sampling circuit, balancing circuit and battery management system of the present application collect the first voltage value at both ends of the first sampling resistor through the sampling module, and determine the current value flowing through the first sampling resistor in combination with the resistance value of the first sampling resistor to obtain the first balancing current passing through the balancing resistor, so as to obtain the balancing current of the target battery cell in real time, avoiding the problem that the error in the theoretical calculation of the balancing current in the traditional way affects the calculation accuracy of the battery SOC. The present application obtains the balanced current through real-time sampling, and the obtained balanced current has high accuracy, which can further improve the SOC calculation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 A schematic diagram of a balanced current sampling circuit according to an embodiment;

[0028] Figure 2 A schematic diagram of a balanced current sampling circuit according to another embodiment;

[0029] Figure 3 is a schematic diagram of a daisy chain structure of an embodiment;

[0030] Figure 4 A schematic diagram of a balanced current sampling circuit according to another embodiment;

[0031] Figure 5 is a schematic diagram of an equalization circuit according to an embodiment;

[0032] Figure 6 FIG. 4 is a schematic diagram of an equalizing circuit according to another embodiment.

[0033] Description of reference numerals:

[0034] 102, balancing module; 104, balancing resistor; 106, first sampling resistor; 108, sampling module; 110, common resistor; 200, target battery cell; 300, analog front end; 302, first analog front end; 304, second analog front end; 402, external power supply; 404, selection switch; 406, second sampling resistor; 408, main control chip. DETAILED DESCRIPTION

[0035] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0037] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0038] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0039] It can be understood that “at least one” means one or more, “plurality” means two or more, and “at least a portion of an element” means a part or all of an element.

[0040] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0041] like Figure 1 As shown, the present application provides a balanced current sampling circuit, which is applied to the balanced current sampling when each battery cell in a battery pack is balanced. Figure 1 As shown, the battery pack includes a plurality of cells, each of which is connected to the analog front end 300. For the target cell 200 whose balanced current is to be sampled, the balanced current sampling circuit includes a balanced module 102 and a sampling module 108, a balanced resistor 104 arranged in the balanced module 102, and a first sampling resistor 106 connected in series with the balanced resistor 104. Among them, the balanced resistor 104 is arranged between the target cell 200 and the analog front end 300, and is used to perform a balanced operation on the target cell 200 according to the balanced signal of the analog front end 300; the sampling module 108 is respectively connected to the first sampling resistor 106 and the analog front end 300, and is used to collect the first voltage value at both ends of the first sampling resistor 106, and determine the current value flowing through the first sampling resistor 106 in combination with the resistance value of the first sampling resistor 106, so as to obtain the balanced current value passing through the balanced resistor 104, and then determine the first balanced current value for performing a balanced operation on the target cell 200.

[0042] Among them, the analog front end (AFE) is an analog system that integrates ADC, amplifier, reference source, excitation circuit, modulation and demodulation circuit, etc., and is widely used in various high-precision measurement fields. In the battery management system, the analog front end 300 is connected to each battery cell in the battery pack to collect data such as voltage and temperature of each battery cell, and send the collected data to the main control chip of the battery management system.

[0043] The balancing operation of each battery cell can be realized by the control of the analog front end 300, that is, when the target battery cell 200 needs to be balanced, the analog front end 300 controls the balancing module 102 connected to the target battery cell 200 to be turned on. When the target battery cell 200 does not need to be balanced, the analog front end 300 controls the balancing module 102 connected to the target battery cell 200 to be disconnected. The balancing module 102 includes a balancing resistor 104 that generates heat and other methods to consume the energy of the target battery cell 200, which is also called passive balancing. A balancing switch can also be provided in the balancing module 102, and the balancing switch can be a MOS tube.

[0044] When the capacity of the battery pack is inconsistent, that is, when battery imbalance is detected, a balancing circuit is formed by closing the balancing switch in the balancing module 102, and the target battery cell 200 that causes the inconsistent capacity of the battery pack is discharged through the balancing resistor 104 to consume the excessive energy, thereby reducing the capacity gap between the battery cells of the battery pack and finally reaching a balanced state.

[0045] In this embodiment, a first sampling resistor 106 is provided in series with the balancing resistor 104, and the sampling module 108 samples the voltage value at both ends of the first sampling resistor 106 to obtain a first resistance value, and the current value passing through the first sampling resistor 106 is determined in combination with the resistance value of the first sampling resistor 106 to obtain the balancing current value passing through the balancing resistor 104, thereby achieving accurate sampling of the balancing current. In order to ensure the accuracy of the sampling of the balancing current value and reduce the voltage division of the first sampling resistor 106, the resistance value of the first sampling resistor 106 is set to be much smaller than that of the balancing resistor 104.

[0046] It can be understood that the first sampling resistor 106 can be set in the balancing module 102 or outside the balancing module 102. As long as the first sampling resistor 106 is connected in series with the balancing resistor 104, the first balancing current value passing through the balancing resistor 104 can be determined by sampling the current value flowing through the first sampling resistor 106.

[0047] The sampling module 108 may be a voltage acquisition chip including a voltage sensor, a digital-to-analog conversion module, and a signal processing unit. The sampling module 108 is connected to the first sampling resistor 106 to sample the voltage across the first sampling resistor 106, so that the analog front end 300 can determine the first balancing current value based on the first voltage value obtained by sampling.

[0048] This embodiment can collect accurate balancing current values ​​through the sampling module 108. Compared with the traditional method of obtaining balancing current by estimation, balancing control based on the balancing current obtained in this embodiment can improve the accuracy of battery pack balancing and improve the reliability of battery pack balancing.

[0049] In some further embodiments, referring to Figure 2 As shown, the analog front end 300 includes a first analog front end 302 and a second analog front end 304. The first analog front end 302 is used to connect with the equalization module 102 to perform an equalization operation on the target battery cell 200. The second analog front end 304 is used to connect with the sampling module 108 to implement sampling of the first equalization current value of the target battery cell 200.

[0050] For example, when performing balanced current sampling on the target battery cell 200, the analog front end 300 for performing balanced control and current sampling on the target battery cell 200 may be separately arranged. Figure 2 As shown, a first analog front end 302 and a second analog front end 304 are provided, and the first analog front end 302 is also used to collect data such as the normal voltage and temperature of the target battery cell 200 .

[0051] When no balancing operation is performed on the battery cells, the second analog front end 304 may not work or sleep, and only the first analog front end 302 normally samples the voltage and temperature data of the target battery cell 200. When the battery cells of the battery pack are balancing, the first analog front end 302 controls the balancing module 102 to perform balancing operation on the target battery cell 200, and the second analog front end 304 controls the sampling module 108 to sample the voltage across the first sampling resistor 106 connected in series with the balancing resistor 104, so as to obtain the balancing current of the target battery cell 200 during the balancing operation.

[0052] In some embodiments, when the battery management system is in an abnormal working state, such as when the system is under high voltage, or when the balancing working mode is prohibited, the first analog front end 302 is set to a dormant monitoring state. At this time, the first analog front end 302 only monitors the voltage of the target battery cell 200, and does not perform balancing control on the target battery cell 200. When the battery is at risk of thermal runaway such as overvoltage, undervoltage or undertemperature, the first analog front end 302 performs balancing control on the target battery cell 200 through the balancing module 102. When the target battery cell 200 is balanced, the second analog front end 304 collects the voltage across the first sampling resistor 106 to collect the balancing current passing through the balancing resistor 104.

[0053] Furthermore, the second analog front end 304 sends the collected balancing current to the battery management system, and the battery management system calculates the balancing capacity of the target battery cell 200 in real time based on the balancing current. For example, the battery capacity can be determined based on the balancing current collected during a preset time period by the ampere-hour integration method. That is, the accumulated value obtained by integration based on the collected balancing current and the time when the balancing is turned on is the balancing capacity corresponding to the target battery cell 200.

[0054] In one implementation, the calculation of the battery SOC may be accumulated in real time or periodically.

[0055] Traditional SOC calculation can be done by current integration method or open circuit voltage method. Current integration is to get the battery SOC by integrating the battery charge and discharge current. Open circuit voltage is to collect the open circuit voltage of the battery without load, and get the battery SOC through the preset open circuit voltage and SOC mapping table.

[0056] However, whether it is implemented by current integration or open circuit voltage method, the capacity consumed during balancing control is not considered, resulting in low SOC calculation accuracy. This embodiment can correct the SOC of the battery pack according to the balancing capacity of the target battery cell 200. For example, if the balancing of the target battery cell 200 for one hour consumes 10Ah balancing capacity, the system capacity is subtracted by 10Ah, and the SOC value is changed accordingly.

[0057] The ampere-hour integration method is a method of calculating the battery power by accumulating current and time. Since the calculation of the state of charge by the ampere-hour integration method needs to be based on the measured current, the accuracy of the current measurement will directly affect the accuracy of the power calculation. In this embodiment, the current of the target battery cell 200 during the balancing operation is obtained by the sampling module 108, which avoids the problem that the error in the traditional method of theoretically calculating the balancing current affects the accuracy of the battery SOC calculation. By improving the accuracy of the balancing current, the SOC calculation accuracy can be improved.

[0058] In some specific embodiments, the second analog front end 304 may also be connected to sampling modules corresponding to other battery cells to collect voltage values ​​of other sampling resistors to obtain balanced current values ​​of other sampling resistors.

[0059] In order to reduce the volume and wiring complexity of the balanced current sampling circuit as much as possible, each battery cell of the battery pack can be connected to a second analog front end 304. That is, the balanced current of all battery cells during balancing is collected through a second analog front end 304. Furthermore, the battery cells can be grouped according to the distribution of the battery cells in the battery pack, and the battery cells of each group can be connected to a second analog front end 304.

[0060] The second analog front end 304 can be multiplexed with the first analog front end 302 as an analog front end as needed; a second analog front end 304 can also be independently set up to connect with all the battery cells; or multiple second analog front ends 304 can be set up, each second analog front end 304 is used to connect to some battery cells. It can be understood that this embodiment has no limitation on the number of second analog front ends 304 used to collect the balancing current, as long as the collection of the battery cell balancing current can be achieved.

[0061] In some other embodiments, the first analog front end 302 and the second analog front end 304 are both connected to the main control chip 408. Figure 3 As shown, the first analog front end 302 and the second analog front end 304 are communicatively connected to the main control chip 408 via a daisy chain.

[0062] The main control chip 408 may be a control chip MCU in a battery management system, and the main control chip 408 is connected to each analog front end 300 for communication, receives the collected data sent by each analog front end 300, and also sends a control signal to each analog front end 300. Each analog front end 300 may control each battery cell according to the control signal sent by the main control chip 408.

[0063] like Figure 3As shown, the first analog front end 302 and the second analog front end 304 are connected to the main control chip 408 through a daisy chain. A daisy chain is a network topology structure. In the daisy chain topology structure, each node is connected together in a specific way to form a ring structure, that is, each node is connected to two adjacent nodes, and the last node is connected to the first node to form a closed loop, forming a chain structure similar to a sentence. Figure 3 As shown, each node of the daisy chain includes at least one analog front end 300 .

[0064] Reference Figure 4 In some other embodiments, the balanced current sampling circuit further includes a common resistor 110 , and the common resistor 110 is connected to the balanced module 102 to form a balanced loop.

[0065] The common resistor 110 is connected between the target cell 200 and the analog front end 300. When the target cell 200 is balanced by the balancing module 102, the common resistor 110 and the balancing module 102 form a balancing loop. At the same time, the common resistor 110 can also increase the energy consumption of the target cell 200 by generating heat, etc., so that the energy of the target cell 200 is reduced.

[0066] In some embodiments, the present application provides a balancing circuit, including a balancing current sampling circuit proposed according to any of the above embodiments.

[0067] Furthermore, in some specific embodiments, the balancing circuit includes a circuit structure for active balancing in addition to the balancing current sampling circuit in the above example. Figure 5 As shown, the active balancing circuit includes an external power supply 402 and a selection switch 404. The external power supply 402 can be a 24V power supply. One end of the selection switch 404 is connected to the external power supply 402, and the other end of the selection switch 404 includes a plurality of ports for connecting to each cell in the battery pack, respectively. The selection switch 404 is used to conduct the connection path between the external power supply 402 and the target cell 200.

[0068] For example, when active balancing is required for the target cell 200 of the battery pack, the switch 404 is selected to conduct the connection path between the external power supply 402 and the target cell 200, and the target cell 200 is replenished or discharged through the external power supply 402, so that the target cell 200 can achieve energy transfer. The active balancing of the target cell 200 in this embodiment can achieve high current and short-time balancing.

[0069] In other embodiments, Figure 6As shown, the balancing circuit further includes a second sampling resistor 406. One end of the second sampling resistor 406 is connected to the external power supply 402, and the other end is connected to the selection switch 404. The second balancing current value can be determined according to the voltage value across the second sampling resistor 406.

[0070] The second sampling resistor 406 is disposed between the external power supply 402 and the selection switch 404, and together they form a loop for actively balancing the target battery cell 200. By collecting the voltage across the second sampling resistor 406, the second balancing current when actively balancing the target battery cell 200 can be obtained.

[0071] Taking the above-mentioned example of active balancing as an example, the second balancing current generated when the target battery cell 200 is actively balanced is relatively large. Due to the influence of line resistance, the large second balancing current will cause errors in the analog front end 300 when sampling each battery cell. At this time, the second balancing current of active balancing can be sampled through the second sampling resistor 406, and the voltage difference of the target battery cell 200 is obtained based on the sampled second balancing current value combined with the line resistance, and the target battery cell 200 is compensated, avoiding the estimation method, and the sampling accuracy of the target battery cell 200 can be further improved. Among them, the line resistance can be calculated by the voltage drop within one end time. For example, the voltage data U0 of each battery cell is first collected, and then the balancing operation of the target battery cell 200 is turned on, and the balancing channel with the balancing operation turned on is sampled to obtain the voltage U1. The voltage drop between voltages U0 and U1 is caused by the balancing resistor 104, the line resistance and the internal resistance of the battery cell. Since the balancing resistor 104 and the internal resistance of the battery cell are known, the resistance value of the line resistance can be obtained.

[0072] In some embodiments, Figure 6 For example, the selection switch 404 is also connected to the main control chip 408, and is used to conduct the connection path between the external power supply 402 and the target battery cell 200 according to the main control chip 408; and / or; the second sampling resistor 406 is also connected to the main control chip 408, so that the main control chip 408 determines the second balancing current value according to the voltage value across the second sampling resistor 406.

[0073] Exemplarily, active balancing of each battery cell and collection of balancing current of active balancing can be controlled by the main control chip 408. The selection switch 404 conducts the path between the target battery cell 200 and the external power supply 402 according to the control of the main control chip 408, so that the external power supply 402 replenishes or discharges the target battery cell 200. The main control chip 408 is also used to collect the voltage across the second sampling resistor 406, and obtain the second balancing current value in combination with the known resistance value of the second sampling resistor 406.

[0074] In some embodiments, the balancing current sampling circuit or balancing circuit proposed in the above embodiments may be applied to a battery management system to improve the balancing current sampling of the battery management system when balancing the cells of a battery pack.

[0075] Exemplarily, when the target battery cell 200 is passively balanced, the first voltage value across the first sampling resistor 106 connected in series with the balancing resistor 104 is collected by the analog front end 300 to obtain a first balancing current value, thereby improving the sampling accuracy of the first balancing current and further improving the calculation accuracy of the battery SOC.

[0076] At the same time, when actively balancing the battery cells in the battery pack, the present embodiment can also calculate the second balancing current by collecting the voltage across the second sampling resistor 406, and calculate the voltage difference of the battery cell voltage sampling caused by the second balancing current in combination with the line resistance parameters, and supplement the voltage difference to improve the balancing duty cycle and the accuracy of balancing the battery cells.

[0077] This embodiment can obtain accurate balancing current values ​​in real time by collecting the first balancing current of a single balancing module 102 or the second balancing current of the main circuit during active balancing. When balancing the target battery cell 200, the existence of line resistance will cause a difference between the collected voltage and the actual voltage, which is smaller than the actual voltage. At present, when the industry collects the voltage of the target battery cell 200, it will first suspend the balancing operation and then sample to improve the accuracy of the sampling, but this method makes the current balancing operation not 100% turned on. Based on the balancing current value collected in this embodiment, the voltage drop is calculated, and the battery cell can be compensated to achieve a 100% balancing duty cycle, thereby improving the balancing efficiency. This embodiment corrects the battery SOC through the ampere-hour integration method according to the first balancing current obtained, which can improve the SOC calculation accuracy and avoid the problem of poor SOC calculation accuracy due to the balancing capacity.

[0078] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0079] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0080] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A balancing current sampling circuit, used for balancing current sampling of each cell in a battery pack, characterized in that: The battery pack includes a plurality of cells, each of which is connected to an analog front end. For a target cell to be sampled for balanced current, the balanced current sampling circuit includes: A balancing module, the balancing module comprising a balancing resistor, the balancing resistor being arranged between the target cell and the analog front end, and being used for performing a balancing operation on the target cell according to a balancing signal of the analog front end; A first sampling resistor, connected in series with the balancing resistor; The sampling module is connected to the first sampling resistor and the analog front end respectively, and is used to collect a first voltage value across the first sampling resistor so that the analog front end determines a first balancing current value of the target battery cell according to the first voltage value.

2. The balanced current sampling circuit according to claim 1, characterized in that: The analog front end comprises a first analog front end and a second analog front end, wherein: The first analog front end is used to connect to the balancing module to perform a balancing operation on the target battery cell; The second analog front end is used to connect with the sampling module to implement sampling of the first balancing current value of the target battery cell.

3. The balanced current sampling circuit according to claim 2, characterized in that: The second analog front end can also be connected to sampling modules corresponding to other battery cells to collect voltage values ​​of other sampling resistors to obtain balanced current values ​​of other sampling resistors.

4. The balanced current sampling circuit according to claim 2, characterized in that: The first analog front end and the second analog front end are both connected to a main control chip, and the first analog front end and the second analog front end are communicatively connected to the main control chip via a daisy chain.

5. The balanced current sampling circuit according to claim 1, characterized in that: The balanced current sampling circuit further includes a common resistor, and the common resistor is connected to the balanced module to form a balanced loop.

6. An equalizing circuit, characterized in that: It comprises the balanced current sampling circuit according to any one of claims 1-5.

7. The equalizing circuit according to claim 6, characterized in that: The equalization circuit further comprises: External power supply; A selection switch, one end of which is connected to the external power source, and the other end of which is connected to each battery cell in the battery pack, and the selection switch is used to conduct a connection path between the external power source and the target battery cell.

8. The equalizing circuit according to claim 7, characterized in that: The equalization circuit further comprises: A second sampling resistor, one end of the second sampling resistor is connected to the external power supply, and the other end of the second sampling resistor is connected to the selection switch.

9. The equalizing circuit according to claim 8, characterized in that: The selection switch is also connected to the main control chip, and is used to conduct the connection path between the external power supply and the target battery cell according to the control instruction of the main control chip; and / or; The second sampling resistor is also connected to the main control chip, so that the main control chip determines the second balancing current value according to the voltage value across the second sampling resistor.

10. A battery management system, characterized in that: It comprises the balanced current sampling circuit according to any one of claims 1-5 or the balanced circuit according to any one of claims 6-9.

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