Battery management system and equalization and disconnection diagnosis method

Abstract

The invention provides a battery management system and an equalization and disconnection diagnosis method, and the positive electrode of each battery and the negative electrode of a first battery in the system are respectively coupled to corresponding ports of a battery sampling chip through sampling lines. In the nth equalization and disconnection diagnosis module, the first end of a first MOS tube, the first end of a first resistor and the first end of a second MOS tube are all coupled to the nth sampling line or the (n-1) th sampling line, and the second end of the first MOS tube is coupled to the (n-1) th sampling line or the nth sampling line. The control end of the first MOS tube is coupled to the second end of the first resistor, the control end of the second MOS tube and the current source unit, the second end of the second MOS tube is coupled to the current source unit through the second resistor, and the current source unit outputs first current and second current or is in a closed state based on the control signal. The equalization and disconnection diagnosis module is simple in circuit structure and low in cost, and the current of the disconnection diagnosis function is reduced, so that the system can easily obtain the disconnection contact resistance of the sampling line.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and in particular to a battery management system and a method for balancing and disconnection diagnosis. Background Art

[0002] Balancing and sampling line disconnection diagnosis are core functions of the battery sampling chip in the Battery Management System (BMS). Their reliability and accuracy are directly related to the safe operation of the battery pack.

[0003] In existing technology, to diagnose a sampling line break, the chip's inherent balancing function is typically used. This approach, equivalent to reusing the balancing circuit, results in excessive diagnostic current. This excessive diagnostic current can cause significant changes in battery voltage, leading to unintended battery discharge when balancing is not necessary, affecting battery status and system efficiency. Furthermore, due to the excessive diagnostic current, existing technology cannot accurately detect the contact resistance of a sampling line break and can only determine whether a line break exists, failing to achieve more refined fault diagnosis.

[0004] Therefore, how to reduce the diagnostic current so that the system can easily obtain the broken contact resistance of the sampling line while keeping the circuit structure simple and the cost low has become a technical problem that needs to be solved urgently in the industry. Summary of the Invention

[0005] The present invention provides a battery management system and an equalization and disconnection diagnosis method, which solves the technical problem of how to reduce the diagnostic current so that the system can easily obtain the disconnection contact resistance of the sampling line while taking into account the simple circuit structure and low cost.

[0006] According to a first aspect of the present invention, an embodiment of the present invention provides a battery management system, comprising N batteries connected in series and N balancing and disconnection diagnosis modules, wherein the positive electrode of the nth battery is coupled to a corresponding port of a battery sampling chip via an nth sampling line, and the negative electrode of the first battery is coupled to a corresponding port of the battery sampling chip via a 0th sampling line, wherein N is an integer greater than or equal to 1, n is an integer, and N ≥ n ≥ 1; The nth balancing and disconnection diagnosis module includes a first MOS transistor, a second MOS transistor, a first resistor, a second resistor, and a current source unit; The first end of the first MOS transistor, the first end of the first resistor, and the first end of the second MOS transistor are all coupled to the nth sampling line or the n-1th sampling line, the second end of the first MOS transistor is coupled to the n-1th sampling line or the nth sampling line, the control end of the first MOS transistor is respectively coupled to the second end of the first resistor, the control end of the second MOS transistor, and the first end of the current source unit, the second end of the second MOS transistor is coupled to the first end of the current source unit through the second resistor, the second end of the current source unit is coupled to the first voltage terminal, and the control end of the current source unit receives a control signal; The current source unit is configured to: output a first current only when the control signal indicates that a balancing function is performed; When the control signal indicates that a disconnection detection function is performed, outputting a second current, wherein a current value of the first current is greater than a current value of the second current; When the control signal indicates that a shutdown function is performed, the current source unit is turned off.

[0007] Optionally, the resistance of the first resistor is greater than the resistance of the second resistor.

[0008] Optionally, the current source unit includes a first current source, a second current source, a first switch and a second switch; A first end of the first current source is coupled to the control end of the first MOS transistor, a first end of the second current source is coupled to the control end of the first MOS transistor, a second end of the first current source and a second end of the second current source are both coupled to the first voltage end, the first switch is connected in series in a path formed by the first voltage end, the first current source, and the first end of the current source unit, and the second switch is connected in series in a path formed by the first voltage end, the second current source, and the first end of the current source unit, and the control end of the first switch and the control end of the second switch both receive a control signal; The on / off of the first switch and the on / off of the second switch are both controlled by the control signal, and the control signal includes a balance signal, a line break diagnosis signal, and a shutdown signal, wherein: When the equalization signal is received, the working state of the equalization and disconnection diagnosis module is the equalization mode, and the first switch and the second switch are both closed; When the line break diagnosis signal is received, the working state of the balancing and line break diagnosis module is the line break diagnosis mode, the first switch is closed, and the second switch is opened; When the shutdown signal is received, the working state of the balancing and disconnection diagnosis module is the shutdown mode, and the first switch and the second switch are both disconnected.

[0009] Optionally, the current value provided by the second current source is greater than the current value provided by the first current source.

[0010] Optionally, the battery management system further includes a control module and a disconnection detection module; The control module is used to send corresponding control signals to N equalization and disconnection diagnosis modules respectively to control the working status of each equalization and disconnection diagnosis module; The line break detection module is used to obtain the voltage on each sampling line, and obtain the impedance value of each sampling line based on the voltage on each sampling line.

[0011] Optionally, corresponding control signals are sent to the N balancing and disconnection diagnosis modules respectively to control the working state of each balancing and disconnection diagnosis module, including: Sending a line break diagnosis signal to all odd-numbered equalization and line break diagnosis modules, and sending a shutdown signal to all even-numbered equalization and line break diagnosis modules; A line break diagnosis signal is sent to all even-numbered equalization and line break diagnosis modules, and a shutdown signal is sent to all odd-numbered equalization and line break diagnosis modules.

[0012] Optionally, obtaining the impedance values ​​of the first sampling line to the N-1th sampling line includes: When the status signal indicates that the control module sends a line break diagnosis signal to all odd-numbered balancing and line break diagnosis modules and sends a shutdown signal to all even-numbered balancing and line break diagnosis modules, collecting a first voltage from a port corresponding to a first sampling line to a port corresponding to an N-1th sampling line; When the state signal indicates that the control module sends a line break diagnosis signal to all even-numbered balancing and line break diagnosis modules and sends a shutdown signal to all odd-numbered balancing and line break diagnosis modules, collecting a second voltage from the port corresponding to the first sampling line to the port corresponding to the N-1th sampling line; The impedance values ​​of the first sampling line to the (N−1)th sampling line are determined based on the voltage difference between each first voltage and the corresponding second voltage and the current value of the second current.

[0013] Optionally, obtaining the impedance value of the Nth sampling line and the impedance value of the 0th sampling line includes: When the status signal indicates that the line break diagnosis signal is stopped from being sent to each of the equalization and line break diagnosis modules, respectively collecting a first cell voltage between the Nth sampling line channel and the N-1th sampling line channel, and a third cell voltage between the 1st sampling line channel and the 0th sampling line channel; When the status signal is characterized by sending a line break diagnostic signal to each of the balancing and line break diagnostic modules, based on the parity of the Nth sampling line channel, a second cell voltage between the Nth sampling line channel and the N-1th sampling line channel is collected; wherein, when N is an odd number, the second cell voltage is collected when the status signal is characterized by the control module sending a line break diagnostic signal to all odd-numbered balancing and line break diagnostic modules and sending a shutdown signal to all even-numbered balancing and line break diagnostic modules; when N is an even number, the second cell voltage is collected when the status signal is characterized by the control module sending a line break diagnostic signal to all even-numbered balancing and line break diagnostic modules and sending a shutdown signal to all odd-numbered balancing and line break diagnostic modules; When the status signal is characterized by the control module sending a line break diagnosis signal to all odd-numbered balancing and line break diagnosis modules and sending a shutdown signal to all even-numbered balancing and line break diagnosis modules, collecting a fourth cell voltage between the first sampling line channel and the zero sampling line channel; Obtaining an impedance value of the Nth sampling line based on a voltage difference between the first battery cell voltage and the second battery cell voltage and a current value of the second current; An impedance value of the 0th sampling line is obtained based on a voltage difference between the third cell voltage and the fourth cell voltage and a current value of the second current.

[0014] Optionally, the first MOS transistor includes M first sub-MOS transistors connected in parallel, and the sizes of the first sub-MOS transistors match those of the second MOS transistor, where M is an integer greater than or equal to 1.

[0015] Optionally, the first MOS transistor and the second MOS transistor are both PMOS transistors, the first voltage end is a ground voltage, and the first end of the first MOS transistor, the first end of the first resistor, and the first end of the second MOS transistor are all coupled to the nth sampling line, and the second end of the first MOS transistor is coupled to the n-1th sampling line.

[0016] Optionally, the first MOS transistor and the second MOS transistor are both NMOS transistors, the first voltage end is the supply voltage, and the first end of the first MOS transistor, the first end of the first resistor, and the first end of the second MOS transistor are all coupled to the n-1th sampling line, and the second end of the first MOS transistor is coupled to the nth sampling line.

[0017] Optionally, a balancing resistor is connected in series between the sampling line and the battery sampling chip.

[0018] According to a second aspect of the present invention, an embodiment of the present invention provides a method for balancing and disconnection diagnosis, which is applied to the battery management system according to any one of the first aspects of the present invention, and the method includes: When the nth battery needs to be balanced, perform the following steps: controlling the current source unit in the nth balancing and disconnection diagnosis module to output a first current; When diagnosing a broken line for each sampling line, perform the following steps: When no line break diagnosis signal is sent to each of the balancing and line break diagnosis modules, respectively collecting a first cell voltage between the Nth sampling line channel and the N-1th sampling line channel, and a third cell voltage between the 1st sampling line channel and the 0th sampling line channel; Controlling the current source units in all odd-numbered balancing and disconnection diagnosis modules to output the second current, and controlling the current source units in all even-numbered balancing and disconnection diagnosis modules to be turned off, and collecting the first voltage from the port corresponding to the first sampling line to the port corresponding to the N-1th sampling line, the fourth cell voltage between the first sampling line channel and the zeroth sampling line channel, and when N is an odd number, collecting the second cell voltage between the Nth sampling line channel and the N-1th sampling line channel; Controlling the current source units of all even-numbered balancing and disconnection diagnosis modules to output the second current, and controlling the current source units of all odd-numbered balancing and disconnection diagnosis modules to be turned off, and collecting the second voltage from the port corresponding to the first sampling line to the port corresponding to the (N-1)th sampling line, and when N is an even number, collecting the second cell voltage between the (N)th sampling line channel and the (N-1)th sampling line channel; Obtaining an impedance value from the port corresponding to the first sampling line to the (N-1)th sampling line based on a voltage difference between each first voltage and the corresponding second voltage and a current value of the second current; Obtaining an impedance value of the Nth sampling line and an impedance value of the 0th sampling line based on a voltage difference between the first cell voltage and the second cell voltage, a voltage difference between the third cell voltage and the fourth cell voltage, and a current value of the second current; Based on the impedance value of each sampling line, the fault degree of each sampling line is determined.

[0019] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects: In the battery management system of the technical solution of the present invention, the positive electrode of each battery and the negative electrode of the first battery are respectively coupled to the corresponding ports of the battery sampling chip via sampling lines. In the nth balancing and disconnection diagnosis module, the first end of the first MOS tube, the first end of the first resistor, and the first end of the second MOS tube are all coupled to the nth sampling line or the n-1th sampling line. The second end of the first MOS tube is coupled to the n-1th sampling line or the nth sampling line. The control end of the first MOS tube is respectively coupled to the second end of the first resistor, the control end of the second MOS tube, and the current source unit. The second end of the second MOS tube is coupled to the current source unit via the second resistor. The current source unit outputs the first current, the second current, or is in an off state based on a control signal. The balancing and disconnection diagnosis module of the present invention has a simple circuit structure, low cost, and reduces the current of the disconnection diagnosis function, making it easy for the system to obtain the disconnection contact resistance of the sampling line.

[0020] In the balancing and disconnection diagnosis method of the technical solution of the present invention, when the nth battery needs to be balanced, the method controls the current source unit in the nth balancing and disconnection diagnosis module to output a first current to complete the voltage balancing function; when the N batteries need to be disconnected, the first cell voltage of the Nth battery and the third cell voltage of the first battery are respectively detected; the parity on and off of the balancing and disconnection diagnosis module are controlled, and the first and second voltages corresponding to the ports of each sampling line and the fourth cell voltage of the first battery are respectively collected, and the second cell voltage of the Nth battery is collected based on the parity of N. Based on the voltage difference between each first voltage and the corresponding second voltage, the voltage difference between the first cell voltage and the second cell voltage, the voltage difference between the third cell voltage and the fourth cell voltage, and the current value of the second current, the impedance value from the 0th sampling line to the Nth sampling line is obtained, and the fault degree of each sampling line is determined based on the impedance value of each sampling line. Because this method uses the balancing and disconnection diagnosis module provided by the present invention, the current of the disconnection diagnosis function is small, and the system obtains the disconnection contact resistance of the sampling line more accurately. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0022] Figure 1 is a schematic structural diagram of a battery management system in an embodiment; Figure 2 is a schematic structural diagram of an equalization circuit in an embodiment; Figure 3is a schematic structural diagram of a battery management system in an embodiment of the present invention; Figure 4 It is a structural diagram of the equalization and disconnection diagnosis module in one embodiment of the present invention; Figure 5 is a structural diagram of an equalization and disconnection diagnosis module in another embodiment of the present invention; Figure 6 is a schematic structural diagram of a battery management system in another embodiment of the present invention; Figure 7 It is a flowchart of a method for balancing and line breakage diagnosis in one embodiment of the present invention. DETAILED DESCRIPTION

[0023] As described in the background art, it is difficult to reduce the diagnostic current in the prior art, so that the system can easily obtain the disconnection contact resistance of the sampling line while keeping the circuit structure simple and the cost low.

[0024] Figure 1 This is a schematic diagram of the battery management system. N battery cells are connected in series to form a battery string. The data acquisition channels for these N cells are divided into odd-channel data acquisition lines (L1, L3, etc.), even-channel data acquisition lines (L2, L4, etc.), and a ground data acquisition line (L0). Each data acquisition line is connected to the corresponding balancing port of the battery cell data acquisition chip through a corresponding balancing resistor.

[0025] exist Figure 1 In the embodiment, the first voltage and the second voltage of the acquisition port corresponding to each acquisition line can be respectively acquired by the odd-even on-off of the internal balancing circuit of the battery cell acquisition chip, and the first voltage and the second voltage can be used to detect whether each acquisition line harness has a circuit breaker fault.

[0026] It should be understood that Figure 1 Only the equalization circuit between a pair of adjacent equalization ports is shown; the equalization circuit also exists between other adjacent equalization ports.

[0027] This approach, equivalent to reusing the balancing circuit, results in excessive diagnostic current. This excessive diagnostic current can cause significant changes in battery voltage, leading to unintended battery discharge due to diagnostic requirements when balancing is not necessary, impacting battery status and system efficiency. Furthermore, due to the excessive diagnostic current, existing technology cannot accurately detect the contact resistance of a broken sampling line. It can only determine whether a broken line fault exists, preventing more refined fault diagnosis.

[0028] To solve the above problem of excessive current in disconnection diagnosis, please refer to Figure 2 , Figure 2This is another balancing circuit between adjacent balancing ports. In this embodiment, adjacent balancing ports are connected in series with a balancing and disconnection diagnosis module. The balancing and disconnection diagnosis module includes a balancing function circuit and a disconnection diagnosis function circuit connected in parallel. The balancing function circuit and the disconnection diagnosis function circuit are controlled by different control signals.

[0029] Obviously, this method requires the provision of independent MOS tubes and control circuits, which results in redundant designs and increases chip area.

[0030] To address the above-mentioned issues, an embodiment of the present invention provides a battery management system, in which the positive electrode of each battery and the negative electrode of the first battery are respectively coupled to corresponding ports of a battery sampling chip via sampling lines. In the nth balancing and disconnection diagnosis module, the first MOS transistor, the first end of the first resistor, and the first end of the second MOS transistor are all coupled to the nth sampling line or the n-1th sampling line, the second end of the first MOS transistor is coupled to the n-1th sampling line or the nth sampling line, the control end of the first MOS transistor is respectively coupled to the second end of the first resistor, the control end of the second MOS transistor, and the current source unit, and the second end of the second MOS transistor is coupled to the current source unit via the second resistor. The current source unit outputs the first current, the second current, or is in an off state based on a control signal. The balancing and disconnection diagnosis module of the present invention has a simple circuit structure, low cost, and reduces the current of the disconnection diagnosis function, making it easy for the system to obtain the disconnection contact resistance of the sampling line.

[0031] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] The terms "first," "second," "third," "fourth," and so on (if any) in the description and claims of the present invention and in the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in orders other than those illustrated or described herein. In addition, the terms "including" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements explicitly listed, but may include other steps or elements not explicitly listed or inherent to such processes, methods, products, or apparatuses.

[0033] The technical solution of the present invention is described in detail below with reference to specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0034] Figure 3 A battery management system according to an embodiment of the present invention includes N battery cells connected in series and N balancing and disconnection diagnosis modules 201. The positive electrode of the nth battery cell is coupled to a corresponding port of the battery sampling chip 20 via an nth sampling line, and the negative electrode of the first battery cell is coupled to a corresponding port of the battery sampling chip 20 via a 0th sampling line. N is an integer greater than or equal to 1, n is an integer, and N ≥ n ≥ 1.

[0035] Please continue to refer to Figure 3 In actual operation, a balancing resistor R is connected in series between the sampling line and the battery sampling chip 20. dis .

[0036] Please refer to Figure 4 as well as Figure 5 In one embodiment, the nth balancing and disconnection diagnosis module 201 includes a first MOS transistor M1, a second MOS transistor M2, a first resistor R1, a second resistor R2, and a current source unit 2012; A first end of the first MOS transistor M1, a first end of the first resistor R1, and a first end of the second MOS transistor M2 are all coupled to the nth sampling line or the n-1th sampling line, a second end of the first MOS transistor is coupled to the n-1th sampling line or the nth sampling line, a control end of the first MOS transistor M1 is coupled to the second end of the first resistor R1, the control end of the second MOS transistor M2, and the first end of the current source unit 2012, respectively, a second end of the second MOS transistor M2 is coupled to the first end of the current source unit 2012 via the second resistor R2, a second end of the current source unit 2012 is coupled to the first voltage end, and a control end of the current source unit 2012 receives a control signal; The current source unit 2012 is configured to: output a first current only when the control signal indicates that a balancing function is to be performed; When the control signal indicates that a disconnection detection function is performed, outputting a second current, wherein a current value of the first current is greater than a current value of the second current; When the control signal indicates that the shutdown function is to be performed, the current source unit 2012 is turned off.

[0037] The first MOS transistor M1 can be considered the balancing MOS transistor between the balancing pins. To ensure that the on-resistance of the first MOS transistor M1 is approximately 1Ω when operating in the linear region, it is typically designed to be larger. The second MOS transistor M2 uses the same single-tube size (finger size) as the first MOS transistor M1 and forms a current mirror with the first MOS transistor M1.

[0038] In a specific embodiment, the first MOS transistor M1 includes M first sub-MOS transistors connected in parallel. The sizes of the first sub-MOS transistors match those of the second MOS transistor M2 , where M is an integer greater than or equal to 1.

[0039] Therefore, by ensuring that the sizes of the first sub-MOS transistor and the second sub-MOS transistor M2 match, the present invention ensures the accuracy, stability and design consistency of the current mirror structure.

[0040] In actual implementation, the resistance of the first resistor R1 is greater than the resistance of the second resistor R2. For example, the first resistor R1 can be in the megohm range, and the second resistor R2 can be in the hundreds of kilohm range.

[0041] exist Figure 4 In the example, the first MOS transistor M1 and the second MOS transistor M2 are both PMOS transistors, the first voltage terminal is the ground voltage, and the first terminal of the first MOS transistor M1, the first terminal of the first resistor R1, and the first terminal of the second MOS transistor M2 are all coupled to the nth sampling line, and the second terminal of the first MOS transistor M1 is coupled to the (n-1)th sampling line.

[0042] Of course, the present invention is not limited to this, please refer to Figure 5 In another embodiment, the first MOS transistor M1 and the second MOS transistor M2 may both be NMOS transistors, the first voltage end is the supply voltage, and the first end of the first MOS transistor M1, the first end of the first resistor R1, and the first end of the second MOS transistor M2 are all coupled to the (n-1)th sampling line, and the second end of the first MOS transistor M1 is coupled to the (n)th sampling line.

[0043] In actual use, the balancing and disconnection diagnosis module 201 provided by the present invention can be set in the battery sampling chip 20. The present invention combines the balancing circuit and the disconnection diagnosis function circuit. When the system turns on the balancing function, the first MOS tube M1 and the second MOS tube M2 both work in a linear switching state, and the balancing current is generated by the balancing resistor R disWhen the system turns on the line break diagnosis function, the first MOS tube M1 and the second MOS tube M2 work in the current mirror saturation state. At this time, the diagnostic current is precisely controlled by the chip. Generally, the current range of the diagnostic current is designed to be hundreds of microamperes (μA) to 1 milliampere (mA).

[0044] Regarding the current source unit 2012, in a specific implementation, please continue to refer to Figure 5 , the current source unit 2012 includes a first current source 20121, a second current source 20122, a first switch S1 and a second switch S2; A first end of the first current source 20121 is coupled to the control end of the first MOS transistor M1, a first end of the second current source 20122 is coupled to the control end of the first MOS transistor M1, a second end of the first current source 20121 and a second end of the second current source 20122 are both coupled to the first voltage end, the first switch S1 is connected in series in a path formed by the first voltage end, the first current source 20121, and the first end of the current source unit, and the second switch S2 is connected in series in a path formed by the first voltage end, the second current source 20122, and the first end of the current source unit, and the control end of the first switch S1 and the control end of the second switch S2 both receive a control signal; The on / off of the first switch S1 and the on / off of the second switch S2 are both controlled by the control signal, and the control signal includes a balance signal, a line break diagnosis signal, and a shutdown signal, wherein: When the equalization signal is received, the working state of the equalization and disconnection diagnosis module 201 is the equalization mode, and the first switch S1 and the second switch S2 are both closed; When the line break diagnosis signal is received, the working state of the equalization and line break diagnosis module 201 is the line break diagnosis mode, the first switch S1 is closed, and the second switch S2 is opened; When the shutdown signal is received, the working state of the balancing and disconnection diagnosis module 201 is the shutdown mode, and the first switch S1 and the second switch S2 are both disconnected.

[0045] exist Figure 5In the example, when the system enters balanced mode, the total bias current provided by the system is a first current I1, which can be designed to be in the microampere (μA) range. Most of this current flows through the first resistor R1, maintaining the gate-source voltage VGS of the first MOS transistor M1 and the second MOS transistor M2 at a designed value, thereby placing the first MOS transistor M1 and the second MOS transistor M2 in a linear switching state. It should be understood that this designed value cannot exceed the gate withstand voltage of the first MOS transistor M1 and the second MOS transistor M2. For example, this designed value can be 4-5V. This is not a limitation of the present invention, and those skilled in the art can select an appropriate design value as needed.

[0046] How to select corresponding battery cells for balancing operation is a conventional operation in the art and will not be described in detail in the present invention.

[0047] When the system enters the disconnection diagnosis mode, the total bias current provided by the system is I2, which can be designed to be in the hundreds of nanoamperes (nA) level. At this time, most of the current flows through the second MOS transistor M2, and the gate-source voltage VGS generated is near the device threshold voltage (about 0.7 V), causing the first MOS transistor M1 and the second MOS transistor M2 to operate in the saturation region, forming a current mirror structure. At this time, the disconnection diagnosis current I M0 =M*I2, this current is generally designed to be between hundreds of microamperes (μA) and several milliamperes (mA) to achieve precise control of the wire break diagnosis current.

[0048] By precisely controlling the disconnection diagnosis current, the disconnection contact resistance on the sampling line can be detected. Figure 6 , the battery management system further includes a control module 202 and a disconnection detection module 203; The control module 202 is used to send corresponding control signals to the N equalization and disconnection diagnosis modules 201 respectively to control the working state of each equalization and disconnection diagnosis module 201; The line break detection module 203 is configured to obtain the voltage on each sampling line, and obtain the impedance value of each sampling line based on the voltage on each sampling line.

[0049] The impedance value of each sampling line can be understood as the disconnection resistance of the sampling line. In actual use, the impedance value of each sampling line can be used to determine whether the sampling line can continue to be used.

[0050] In actual use, the disconnection detection module 203 can be used through the acquisition port (C <0> ~C <n>) directly obtain the voltage on each sampling line. Of course, the present invention is not limited to this, and those skilled in the art can select a suitable acquisition method as needed.

[0051] In a preferred embodiment, the control module 202 may generate a status signal to the disconnection detection module 203 , wherein the status signal is used to represent the working state of the battery management system, so that the disconnection detection module 203 can collect the voltage of each sampling line in different states.

[0052] In a specific embodiment, corresponding control signals are sent to N balancing and disconnection diagnosis modules respectively to control the working state of each balancing and disconnection diagnosis module, including: Sending a line break diagnosis signal to all odd-numbered equalization and line break diagnosis modules 201, and sending a shutdown signal to all even-numbered equalization and line break diagnosis modules 201; A line-breakage diagnosis signal is sent to all even-numbered equalization and line-breakage diagnosis modules 201 , and a shutdown signal is sent to all odd-numbered equalization and line-breakage diagnosis modules 201 .

[0053] In the system of the present invention, the N balancing and disconnection diagnostic modules 201 are arranged in sequence. The odd-numbered balancing and disconnection diagnostic modules 201 mentioned above can be understood as balancing and disconnection diagnostic modules 201 with odd sequence numbers among the N balancing and disconnection diagnostic modules 201. Similarly, the even-numbered balancing and disconnection diagnostic modules 201 mentioned above can be understood as balancing and disconnection diagnostic modules 201 with even sequence numbers among the N balancing and disconnection diagnostic modules 201.

[0054] On this basis, the impedance values ​​of the first sampling line to the N-1th sampling line are obtained, including: When the state signal indicates that the control module 202 sends a line break diagnosis signal to all odd-numbered balancing and line break diagnosis modules 201 and sends a shutdown signal to all even-numbered balancing and line break diagnosis modules 201, a first voltage from a port corresponding to a first sampling line to a port corresponding to an nth sampling line is collected; When the state signal indicates that the control module 202 sends a line break diagnosis signal to all even-numbered balancing and line break diagnosis modules 201 and sends a shutdown signal to all odd-numbered balancing and line break diagnosis modules 201, a second voltage from the port corresponding to the first sampling line to the port corresponding to the nth sampling line is collected; Based on the voltage difference between each first voltage and the corresponding second voltage and the current value of the second current, the impedance values ​​of the 1st sampling line to the N-1th sampling line are obtained.

[0055] Obtain the impedance value of the Nth sampling line and the impedance value of the 0th sampling line, including: When the state signal indicates that the line break diagnosis signal is stopped from being sent to each of the equalization and line break diagnosis modules 201, respectively collecting the first cell voltage between the Nth sampling line channel and the N-1th sampling line channel, and the third cell voltage between the 1st sampling line channel and the 0th sampling line channel; When the status signal is characterized by sending a line break diagnosis signal to each of the balancing and line break diagnosis modules 201, based on the parity of the Nth sampling line channel, the second cell voltage between the Nth sampling line channel and the N-1th sampling line channel is collected; wherein, when N is an odd number, the second cell voltage is collected when the status signal is characterized by the control module 202 sending a line break diagnosis signal to all odd-numbered balancing and line break diagnosis modules 201 and sending a shutdown signal to all even-numbered balancing and line break diagnosis modules 201; when N is an even number, the second cell voltage is collected when the status signal is characterized by the control module 202 sending a line break diagnosis signal to all even-numbered balancing and line break diagnosis modules 201 and sending a shutdown signal to all odd-numbered balancing and line break diagnosis modules 201; When the status signal is characterized by the control module sending a line break diagnosis signal to all odd-numbered balancing and line break diagnosis modules and sending a shutdown signal to all even-numbered balancing and line break diagnosis modules, collecting a fourth cell voltage between the first sampling line channel and the zero sampling line channel; Obtaining an impedance value of the Nth sampling line based on a voltage difference between the first battery cell voltage and the second battery cell voltage and a current value of the second current; An impedance value of the 0th sampling line is obtained based on a voltage difference between the third cell voltage and the fourth cell voltage and a current value of the second current.

[0056] The method of measuring impedance value of the present invention is now described with examples.

[0057] In order to facilitate the description of the principle of the embodiment of the present invention, N is tentatively set to 16 here, but the number of battery cells in an actual battery string is not uniform and is not limited here; Figure 6 The wiring diagram shows that L0 is at the negative pole of the lowest battery cell, and L16 is at the positive pole of the highest battery cell. Since the sampling lines of L0 and L16 do not correspond to two balancing and line break diagnosis modules 201, the impedance value detection of the acquisition line can be divided into three locations for separate detection, namely, the impedance value detection of L0, the impedance value detection of L1 to L15, and the impedance value detection of L16.

[0058] The specific principle of detecting the impedance value of the 0th acquisition line L0 is as follows: when the current source units 2012 in all odd-numbered balancing and disconnection diagnosis modules 201 are controlled to output the second current, and the current source units 2012 in all even-numbered balancing and disconnection diagnosis modules 201 are controlled to be turned off, since the first balancing and disconnection diagnosis module 201 is connected to the port DIS <0> and port DIS <1> Between, port DIS <0> And connected to the earth.

[0059] In this case, as a specific implementation, whether the 0th acquisition line L0 has a line break fault can be determined by measuring the voltage of the acquisition port C1 corresponding to the 1st acquisition line L1. If the voltage is less than the corresponding threshold, the 0th acquisition line L0 has a line break fault; otherwise, the 0th acquisition line L0 has not a line break fault.

[0060] In other embodiments, the line break diagnosis of L0 is similar to the line break diagnosis of the highest channel L16. If the 0th acquisition line L0 is completely broken, then after the line break diagnosis is turned on (that is, after the first balancing and line break diagnosis module 201 is turned on), the cell voltage sampled by the C0 sampling pin is basically 0V.

[0061] If the 0th acquisition line L0 is not completely disconnected, to obtain the disconnection resistance of the 0th acquisition line L0, the sampled voltage value of the cell 1 battery cell voltage when the disconnection diagnosis is enabled is subtracted from the sampled voltage value of the cell 1 battery cell voltage when the disconnection diagnosis is disabled, and the resultant voltage is divided by the disconnection diagnosis current (i.e., the second current value). This yields the disconnection resistance value of the 0th acquisition line L0.

[0062] Taking the detection of the impedance value of the first acquisition line L1 as an example, the specific principle of detecting the impedance values ​​of L1 to L15 is introduced: When the current source units 2012 of all even-numbered balancing and disconnection diagnosis modules 201 are controlled to output the second current and the current source units 2012 of all odd-numbered balancing and disconnection diagnosis modules 201 are controlled to be turned off, the port DIS is turned off. <1> With port DIS <2> The two are connected through the second balance and disconnection diagnosis module 201, and after waiting for a period of time, the port DIS is obtained. <1> The collected second voltage V even .

[0063] When all the current source units 2012 in the odd-numbered balancing and disconnection diagnosis modules 201 are controlled to output the second current and all the current source units 2012 in the even-numbered balancing and disconnection diagnosis modules 201 are controlled to be turned off, the port DIS <1> With port DIS <0> The two are connected through the first balance and disconnection diagnosis module 201, and after waiting for a period of time, the port DIS is obtained. <1> The first voltage V collected odd .

[0064] In this case, the impedance value of the first acquisition line L1 has the relationship: Among them, V odd is the voltage value of the first voltage, V even is the voltage value of the second voltage, and I2 is the magnitude of the second current.

[0065] For the highest channel, if the highest channel is completely disconnected, after the disconnection diagnosis is turned on, C <n>The cell voltage sampled by the sampling pin is basically 0V.

[0066] If the Nth acquisition line LN is not completely disconnected, if you want to get L <n>The wire break resistance is obtained by subtracting the sampled voltage value after the wire break diagnosis is enabled from the sampled voltage value when the wire break diagnosis is not enabled, and then dividing the result by the wire break diagnosis current.

[0067] Furthermore, the specific principle for determining whether the 16th acquisition line L16 has a line break fault is as follows: When the status signal indicates that the line break diagnosis signal is stopped from being sent to each of the equalization and line break diagnosis modules, the fourth voltage of the port corresponding to the 15th sampling line and the fifth voltage of the port corresponding to the 16th sampling line are collected; the first cell voltage V of the highest channel is obtained based on the difference between the fourth voltage and the fifth voltage. CIN1 .

[0068] When the current source units 2012 of all even-numbered balancing and disconnection diagnosis modules 201 are controlled to output the second current and the current source units 2012 of all odd-numbered balancing and disconnection diagnosis modules 201 are controlled to be turned off, the port DIS is turned off. <16> Through the 16th equalization and disconnection diagnosis module 201 and port DIS <15> In this case, after waiting for a period of time, the second cell voltage V of the highest channel is obtained. CIN2 , the cell voltage has the relationship: It can be seen that the present invention can obtain the impedance of all acquisition lines.

[0069] It should be understood that the present invention can obtain the second cell voltage V of the highest channel when sending the line break diagnosis signal to all even-numbered equalization and line break diagnosis modules. CIN2 , or send a line break diagnosis signal to all odd-numbered equalization and line break diagnosis modules to obtain the second cell voltage V of the highest channel CIN2 The specific method to be used depends on the parity of the highest channel number.

[0070] Specifically, if the sequence number of the highest channel is odd, the second cell voltage V of the highest channel is obtained when the control module sends a line break diagnosis signal to all odd-numbered balancing and line break diagnosis modules and sends a shutdown signal to all even-numbered balancing and line break diagnosis modules. CIN2 .

[0071] If the sequence number of the highest channel is even, the second cell voltage V of the highest channel is obtained when the control module sends a line break diagnosis signal to all even-numbered balancing and line break diagnosis modules and sends a shutdown signal to all odd-numbered balancing and line break diagnosis modules. CIN2 .

[0072] In summary, the present invention couples the positive electrode of each battery in the system and the negative electrode of the first battery to corresponding ports of a battery sampling chip via sampling lines. In the nth balancing and disconnection diagnosis module, the first MOS transistor, the first end of the first resistor, and the first end of the second MOS transistor are all coupled to the nth sampling line or the n-1th sampling line. The second end of the first MOS transistor is coupled to the n-1th sampling line or the nth sampling line. The control end of the first MOS transistor is coupled to the second end of the first resistor, the control end of the second MOS transistor, and the current source unit, respectively. The second end of the second MOS transistor is coupled to the current source unit via the second resistor. The current source unit outputs the first current, the second current, or is in an off state based on a control signal. The balancing and disconnection diagnosis module of the present invention has a simple circuit structure, low cost, and reduces the current of the disconnection diagnosis function, making it easy for the system to obtain the disconnection contact resistance of the sampling line.

[0073] In addition, the present invention also provides a method for balancing and disconnection diagnosis, which is applied to the battery management system described above, and the method includes: When the nth battery needs to be balanced, perform the following steps: controlling the current source unit in the nth balancing and disconnection diagnosis module to output a first current; When diagnosing a broken line for each sampling line, perform the following steps: When no line break diagnosis signal is sent to each of the balancing and line break diagnosis modules, respectively collecting a first cell voltage between the Nth sampling line channel and the N-1th sampling line channel, and a third cell voltage between the 1st sampling line channel and the 0th sampling line channel; Controlling the current source units in all odd-numbered balancing and disconnection diagnosis modules to output the second current, and controlling the current source units in all even-numbered balancing and disconnection diagnosis modules to be turned off, and collecting the first voltage from the port corresponding to the first sampling line to the port corresponding to the N-1th sampling line, the fourth cell voltage between the first sampling line channel and the zeroth sampling line channel, and when N is an odd number, collecting the second cell voltage between the Nth sampling line channel and the N-1th sampling line channel; Controlling the current source units of all even-numbered balancing and disconnection diagnosis modules to output the second current, and controlling the current source units of all odd-numbered balancing and disconnection diagnosis modules to be turned off, and collecting the second voltage from the port corresponding to the first sampling line to the port corresponding to the (N-1)th sampling line, and when N is an even number, collecting the second cell voltage between the (N)th sampling line channel and the (N-1)th sampling line channel; Obtaining an impedance value from the port corresponding to the first sampling line to the (N-1)th sampling line based on a voltage difference between each first voltage and the corresponding second voltage and a current value of the second current; Obtaining an impedance value of the Nth sampling line and an impedance value of the 0th sampling line based on a voltage difference between the first cell voltage and the second cell voltage, a voltage difference between the third cell voltage and the fourth cell voltage, and a current value of the second current; Based on the impedance value of each sampling line, the fault degree of each sampling line is determined.

[0074] In a specific embodiment, please refer to Figure 7 , the equalization and disconnection diagnosis method includes: S11: Waiting for a command from the battery sampling chip. When the nth battery needs to be balanced, the process proceeds to step S12. When a disconnection diagnosis is performed on each sampling line, the process proceeds to step S13.

[0075] S12: Control the current source unit in the nth balancing and disconnection diagnosis module to output a first current, and return to step S11.

[0076] S13: When no line break diagnosis signal is sent to each of the equalization and line break diagnosis modules, respectively collecting a first cell voltage between the Nth sampling line channel and the N-1th sampling line channel, and a third cell voltage between the 1st sampling line channel and the 0th sampling line channel; S14: Obtain the parity of N, wherein, when N is an odd number, proceed to step S15; when N is an even number, proceed to step S17; S15: Control the current source units in all odd-numbered balancing and disconnection diagnosis modules to output the second current, and control the current source units in all even-numbered balancing and disconnection diagnosis modules to be turned off, and collect the first voltage from the port corresponding to the first sampling line to the port corresponding to the N-1th sampling line, the fourth cell voltage between the first sampling line channel and the zeroth sampling line channel, and the second cell voltage between the Nth sampling line channel and the N-1th sampling line channel; S16: Control the current source units of all even-numbered balancing and disconnection diagnosis modules to output the second current, control the current source units of all odd-numbered balancing and disconnection diagnosis modules to be turned off, and collect the second voltage from the port corresponding to the first sampling line to the port corresponding to the N-1th sampling line; and proceed to step S19; S17: Control the current source units in all odd-numbered balancing and disconnection diagnosis modules to output the second current, and control the current source units in all even-numbered balancing and disconnection diagnosis modules to be turned off, and collect the first voltage from the port corresponding to the first sampling line to the port corresponding to the N-1th sampling line, and the fourth cell voltage between the first sampling line channel and the zeroth sampling line channel; S18: Control the current source units of all even-numbered balancing and disconnection diagnosis modules to output the second current, and control the current source units of all odd-numbered balancing and disconnection diagnosis modules to be turned off, and collect the second voltage from the port corresponding to the first sampling line to the port corresponding to the N-1th sampling line, and collect the second cell voltage between the Nth sampling line channel and the N-1th sampling line channel; and proceed to step S19; S19: Obtaining an impedance value from the port corresponding to the first sampling line to the (N−1)th sampling line based on a voltage difference between each first voltage and the corresponding second voltage and a current value of the second current; S20: obtaining an impedance value of the Nth sampling line and an impedance value of the 0th sampling line based on a voltage difference between the first cell voltage and the second cell voltage, a voltage difference between the third cell voltage and the fourth cell voltage, and a current value of the second current; S21: Based on the impedance value of each sampling line, determine the fault degree of each sampling line, and return to step S11.

[0077] For example, when the chip detects that the disconnection resistance of a sampling line is within the normal range, it means that the line is well connected; when the resistance value is in the medium to high range, there may be minor faults such as poor contact and increased contact resistance, but the sampling line still has a certain sampling capability and can continue to be used temporarily and record abnormal conditions; if the resistance value exceeds the threshold, it is determined that the sampling line has a serious disconnection fault, and it is necessary to report a fault sign and prompt maintenance or isolation of the channel.

[0078] In one embodiment, the balancing and disconnection diagnosis method is applied to the battery management system in any of the above technical solutions. Therefore, the balancing and disconnection diagnosis method also has all the beneficial effects of the battery management system in the above technical solutions, and the present invention will not be repeated here.

[0079] In summary, in this embodiment, when the nth battery needs to be balanced, the current source unit in the nth balancing and disconnection diagnosis module is controlled to output a first current to complete the voltage balancing function; when disconnection diagnosis is required for the N batteries, the first cell voltage of the Nth battery and the third cell voltage of the first battery are respectively detected; the parity of the balancing and disconnection diagnosis module is controlled, and the first and second voltages of the corresponding ports of each sampling line and the fourth cell voltage of the first battery are respectively collected, and the second cell voltage of the Nth battery is collected based on the parity of N. The impedance value from the 0th sampling line to the Nth sampling line is obtained based on the voltage difference between each first voltage and the corresponding second voltage, the voltage difference between the first cell voltage and the second cell voltage, the voltage difference between the third cell voltage and the fourth cell voltage, and the current value of the second current, and the fault degree of each sampling line is determined based on the impedance value of each sampling line. Because this method uses the balancing and disconnection diagnosis module provided by the present invention, the current of the disconnection diagnosis function is small, and the system obtains the disconnection contact resistance of the sampling line more accurately.

[0080] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.< / n> < / n> < / n>

Claims

1. A battery management system, characterized in that: The device comprises N batteries connected in series and N balancing and disconnection diagnosis modules, wherein the positive electrode of the nth battery is coupled to the corresponding port of the battery sampling chip via the nth sampling line, and the negative electrode of the first battery is coupled to the corresponding port of the battery sampling chip via the 0th sampling line, wherein N is an integer greater than or equal to 1, n is an integer, and N≥n≥1; The nth balancing and disconnection diagnosis module includes a first MOS transistor, a second MOS transistor, a first resistor, a second resistor, and a current source unit; The first end of the first MOS transistor, the first end of the first resistor, and the first end of the second MOS transistor are all coupled to the nth sampling line or the n-1th sampling line, the second end of the first MOS transistor is coupled to the n-1th sampling line or the nth sampling line, the control end of the first MOS transistor is respectively coupled to the second end of the first resistor, the control end of the second MOS transistor, and the first end of the current source unit, the second end of the second MOS transistor is coupled to the first end of the current source unit through the second resistor, the second end of the current source unit is coupled to the first voltage terminal, and the control end of the current source unit receives a control signal; The current source unit is configured to: output a first current only when the control signal indicates performing a balancing function; When the control signal indicates that a disconnection detection function is performed, outputting a second current, wherein a current value of the first current is greater than a current value of the second current; When the control signal indicates that a shutdown function is performed, the current source unit is turned off.

2. The battery management system according to claim 1, wherein: The resistance of the first resistor is greater than the resistance of the second resistor.

3. The battery management system according to claim 1, wherein: The current source unit includes a first current source, a second current source, a first switch and a second switch; A first end of the first current source is coupled to the control end of the first MOS transistor, a first end of the second current source is coupled to the control end of the first MOS transistor, a second end of the first current source and a second end of the second current source are both coupled to the first voltage end, the first switch is connected in series in a path formed by the first voltage end, the first current source, and the first end of the current source unit, and the second switch is connected in series in a path formed by the first voltage end, the second current source, and the first end of the current source unit, and the control end of the first switch and the control end of the second switch both receive a control signal; The on / off of the first switch and the on / off of the second switch are both controlled by the control signal, and the control signal includes a balance signal, a line break diagnosis signal, and a shutdown signal, wherein: When the equalization signal is received, the working state of the equalization and disconnection diagnosis module is the equalization mode, and the first switch and the second switch are both closed; When the line break diagnosis signal is received, the working state of the balancing and line break diagnosis module is the line break diagnosis mode, the first switch is closed, and the second switch is opened; When the shutdown signal is received, the working state of the balancing and disconnection diagnosis module is the shutdown mode, and the first switch and the second switch are both disconnected.

4. The battery management system according to claim 3, characterized in that: The current value provided by the second current source is greater than the current value provided by the first current source.

5. The battery management system according to claim 3, wherein: The battery management system also includes a control module and a disconnection detection module; The control module is used to send corresponding control signals to N equalization and disconnection diagnosis modules respectively to control the working status of each equalization and disconnection diagnosis module; The line break detection module is used to obtain the voltage on each sampling line, and obtain the impedance value of each sampling line based on the voltage on each sampling line.

6. The battery management system according to claim 5, characterized in that: Sending corresponding control signals to N equalization and disconnection diagnosis modules respectively to control the working status of each equalization and disconnection diagnosis module, including: Sending a line break diagnosis signal to all odd-numbered equalization and line break diagnosis modules, and sending a shutdown signal to all even-numbered equalization and line break diagnosis modules; A line break diagnosis signal is sent to all even-numbered equalization and line break diagnosis modules, and a shutdown signal is sent to all odd-numbered equalization and line break diagnosis modules.

7. The battery management system according to claim 6, wherein: Obtain the impedance values ​​from the 1st sampling line to the N-1th sampling line, including: When the status signal indicates that the control module sends a line break diagnosis signal to all odd-numbered balancing and line break diagnosis modules and sends a shutdown signal to all even-numbered balancing and line break diagnosis modules, collecting a first voltage from a port corresponding to a first sampling line to a port corresponding to an N-1th sampling line; When the state signal indicates that the control module sends a line break diagnosis signal to all even-numbered balancing and line break diagnosis modules and sends a shutdown signal to all odd-numbered balancing and line break diagnosis modules, collecting a second voltage from the port corresponding to the first sampling line to the port corresponding to the N-1th sampling line; The impedance values ​​of the first sampling line to the (N−1)th sampling line are determined based on the voltage difference between each first voltage and the corresponding second voltage and the current value of the second current.

8. The battery management system according to claim 6, wherein: Obtain the impedance value of the Nth sampling line and the impedance value of the 0th sampling line, including: When the status signal indicates that the line break diagnosis signal is stopped from being sent to each of the equalization and line break diagnosis modules, respectively collecting a first cell voltage between the Nth sampling line channel and the N-1th sampling line channel, and a third cell voltage between the 1st sampling line channel and the 0th sampling line channel; When the status signal is characterized by sending a line break diagnostic signal to each of the balancing and line break diagnostic modules, based on the parity of the Nth sampling line channel, a second cell voltage between the Nth sampling line channel and the N-1th sampling line channel is collected; wherein, when N is an odd number, the second cell voltage is collected when the status signal is characterized by the control module sending a line break diagnostic signal to all odd-numbered balancing and line break diagnostic modules and sending a shutdown signal to all even-numbered balancing and line break diagnostic modules; when N is an even number, the second cell voltage is collected when the status signal is characterized by the control module sending a line break diagnostic signal to all even-numbered balancing and line break diagnostic modules and sending a shutdown signal to all odd-numbered balancing and line break diagnostic modules; When the status signal is characterized by the control module sending a line break diagnosis signal to all odd-numbered balancing and line break diagnosis modules and sending a shutdown signal to all even-numbered balancing and line break diagnosis modules, collecting a fourth cell voltage between the first sampling line channel and the zero sampling line channel; Obtaining an impedance value of the Nth sampling line based on a voltage difference between the first battery cell voltage and the second battery cell voltage and a current value of the second current; An impedance value of the 0th sampling line is obtained based on a voltage difference between the third cell voltage and the fourth cell voltage and a current value of the second current.

9. The battery management system according to claim 1, wherein: The first MOS transistor includes M first sub-MOS transistors connected in parallel. The sizes of the first sub-MOS transistors match those of the second MOS transistor, where M is an integer greater than or equal to 1.

10. The battery management system according to claim 1, wherein: The first MOS transistor and the second MOS transistor are both PMOS transistors, the first voltage terminal is a ground voltage, and the first terminal of the first MOS transistor, the first terminal of the first resistor, and the first terminal of the second MOS transistor are all coupled to the nth sampling line, and the second terminal of the first MOS transistor is coupled to the (n-1)th sampling line.

11. The battery management system according to claim 1, wherein: The first MOS transistor and the second MOS transistor are both NMOS transistors, the first voltage end is a supply voltage, and the first end of the first MOS transistor, the first end of the first resistor, and the first end of the second MOS transistor are all coupled to the (n-1)th sampling line, and the second end of the first MOS transistor is coupled to the (n)th sampling line. The battery management system according to claim 1, wherein a balancing resistor is further connected in series between the sampling line and the battery sampling chip.

12. A method for balancing and disconnection diagnosis, characterized in that: Applied to the battery management system according to any one of claims 1 to 12, the method comprising: When the nth battery needs to be balanced, perform the following steps: controlling the current source unit in the nth balancing and disconnection diagnosis module to output a first current; When diagnosing a broken line for each sampling line, perform the following steps: When no line break diagnosis signal is sent to each of the balancing and line break diagnosis modules, respectively collecting a first cell voltage between the Nth sampling line channel and the N-1th sampling line channel, and a third cell voltage between the 1st sampling line channel and the 0th sampling line channel; Controlling the current source units in all odd-numbered balancing and disconnection diagnosis modules to output the second current, and controlling the current source units in all even-numbered balancing and disconnection diagnosis modules to be turned off, and collecting the first voltage from the port corresponding to the first sampling line to the port corresponding to the N-1th sampling line, the fourth cell voltage between the first sampling line channel and the zeroth sampling line channel, and when N is an odd number, collecting the second cell voltage between the Nth sampling line channel and the N-1th sampling line channel; Controlling the current source units of all even-numbered balancing and disconnection diagnosis modules to output the second current, and controlling the current source units of all odd-numbered balancing and disconnection diagnosis modules to be turned off, and collecting the second voltage from the port corresponding to the first sampling line to the port corresponding to the (N-1)th sampling line, and when N is an even number, collecting the second cell voltage between the (N)th sampling line channel and the (N-1)th sampling line channel; Obtaining an impedance value from the port corresponding to the first sampling line to the (N-1)th sampling line based on a voltage difference between each first voltage and the corresponding second voltage and a current value of the second current; Obtaining an impedance value of the Nth sampling line and an impedance value of the 0th sampling line based on a voltage difference between the first cell voltage and the second cell voltage, a voltage difference between the third cell voltage and the fourth cell voltage, and a current value of the second current; Based on the impedance value of each sampling line, the fault degree of each sampling line is determined.

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