Battery pack voltage sampling circuit

Abstract

The utility model provides a battery pack voltage sampling circuit which comprises K first sampling units, a second sampling unit and a control unit, K is an integer larger than or equal to 1 and smaller than N, each first sampling unit at least comprises a first sampling channels, a is an integer larger than M, and the second sampling unit at least comprises N-1 second sampling channels; the K first sampling units are connected with the two ends of each battery cell in the N battery modules through first sampling channels; the second sampling channel is connected between the first connecting piece and a target battery cell, and the target battery cell is the last battery cell in the previous battery module in the two adjacent battery modules connected by the first connecting piece. According to the embodiment of the invention, the influence of the first connecting piece on the voltage of the target battery cell is eliminated, the target of accurately collecting the voltage of each battery cell is achieved, and data guarantee is provided for the consistency of the whole system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage, in particular to a battery pack voltage sampling circuit. BACKGROUND

[0002] Electrochemical energy storage technology has become the mainstream choice in the field of energy storage today, and generally electrochemical energy storage technology is monitored and managed by a battery management system. However, a battery system generally forms a battery module by connecting multiple battery cells in series, and then connects one or more battery modules in series and encapsulates them into a battery pack. Multiple battery packs can be connected in series or parallel to form a battery cluster. Therefore, the battery management system monitors and manages the battery module and the battery cluster through hierarchical management. The battery module management unit (BMU) monitors the battery module in real time and uploads the detected data to the battery cluster management unit (BCU). However, since the battery modules are generally connected by a large resistance element (such as a copper bar or an aluminum bar), when current flows through the large resistance element, the voltage across the large resistance element will have a large difference, thereby affecting the accuracy of the voltage collected by the battery cell sampling chip.

[0003] In the prior art, before the large resistance element is connected between the battery modules, different currents are applied to the large resistance element, and the voltage across the large resistance element is detected under different currents. In combination with real-time temperature and resistance factors, the compensation voltage is obtained by comparing with the calibrated parameters of the large resistance element. After the large resistance element is connected between the battery modules, the compensation voltage obtained by experiment is used to obtain the influence of the large resistance element on the collected voltage, and then the accurate data of the large resistance element is obtained.

[0004] The influence of the large resistance element on the collected voltage can be obtained by the prior art, but the voltage compensation obtained by the prior method is inaccurate, and the influence on the voltage is not only the temperature, but also the shape, material and connection method of the large resistance element. Therefore, the collected voltage will still affect the normal operation of the battery system, and the performance of the entire battery system will be reduced. CONTENT OF THE UTILITY MODEL

[0005] The present application provides a battery pack voltage sampling circuit to solve the problems mentioned in the background art.

[0006] The present application provides a battery pack voltage sampling circuit for sampling the voltage of each battery cell in the battery pack. The battery pack includes N battery modules connected in series, N is an integer greater than or equal to 2, the battery module includes M battery cells connected in series, N and M are integers greater than or equal to 2, and each adjacent two battery modules are connected in series by a first connecting piece.

[0007] The battery pack voltage sampling circuit comprises K first sampling units, a second sampling unit and a control unit, K is an integer greater than or equal to 1 and less than N, the first sampling unit comprises at least a first sampling channel, and a is an integer greater than M, the second sampling unit comprises at least N-1 second sampling channels;

[0008] The K first sampling units are connected with both ends of each cell in the N battery modules through the first sampling channels;

[0009] The second sampling channel is connected between the first connecting piece and the target cell, and the target cell is the last cell in the first battery module adjacent to the first connecting piece;

[0010] The control unit is configured to acquire the collected voltage through each first sampling channel and each second sampling channel, and obtain the voltage of each cell in each battery module according to the collected voltage.

[0011] Optionally, the two adjacent cells in the battery module are connected in series through a second connecting piece.

[0012] For each battery module, the two first sampling channels connected with both ends of the first cell are connected on the first connecting piece and the second connecting piece respectively, the first sampling channel and the second sampling channel connected with both ends of the last cell are connected on the second connecting piece and the first connecting piece respectively, and the two first sampling channels connected with both ends of other cells are connected on two second connecting pieces respectively.

[0013] The resistance value of the first connecting piece is greater than the resistance value of the second connecting piece, and the difference between the resistance value of the first connecting piece and the resistance value of the second connecting piece is greater than a preset value.

[0014] Optionally, the K first sampling units are K first sampling chips.

[0015] The second sampling unit is a second sampling chip, or the second sampling unit and the control unit are integrated in the second sampling chip.

[0016] Optionally, the K first sampling units are K first sampling chips, and K*a is less than N*M+N and greater than N*M+1.

[0017] The second sampling unit multiplexes K*a-(N*M+1) first sampling channels in the first sampling unit; and N*M+N-K*a second sampling channels in the second sampling unit are integrated in a second sampling chip.

[0018] Optionally, the K first sampling chips are respectively integrated in K battery module management units BMUs of the battery pack, and the second sampling chip is integrated in a battery cluster management unit BCU of the battery pack; or,

[0019] The K first sampling chips and the second sampling chip are respectively integrated in K+1 BMUs.

[0020] Optionally, the K first sampling units are K first sampling chips, and K*a is greater than or equal to N*M+N.

[0021] The second sampling unit is integrated on one of the K first sampling chips.

[0022] Optionally, the K first sampling chips are respectively integrated in K BMUs of the battery pack.

[0023] Optionally, the first sampling unit or the second sampling channel is connected at both ends of the battery cell through a connecting line and a voltage sensor.

[0024] In the embodiment, the first sampling channels in the K first sampling units collect the voltages at both ends of each battery cell in the N battery modules and send them to the control unit, the N-1 second sampling channels in the second sampling unit collect the voltages between the target battery cells and the first connecting piece in the N-1 battery modules and send them to the control unit, and the voltages of each battery cell in the battery pack are obtained through the control unit. On the basis of the existing first sampling unit for cross-battery module sampling, the present application adds a second sampling unit including N-1 second sampling channels, and a sampling point is newly arranged between each target battery cell and the first connecting piece. The sampling point is close to the target battery cell, and the N-1 second sampling channels are respectively connected to the N-1 sampling points, so as to realize accurate sampling of the voltages of the N-1 target battery cells. Without improving the original first sampling unit for cross-battery module sampling, only by adding the second sampling unit, the influence of the first connecting piece on the voltage of the target battery cell can be reduced, the voltage of each battery cell can be more accurately collected, and data guarantee for the consistency of the whole system is provided. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without any creative effort.

[0026] Figure 1 The structure schematic diagram of the voltage sampling of the battery cell in the prior art provided by an embodiment of the present application during charging;

[0027] Figure 2 A structure diagram of sampling the voltage of an electric cell during discharging in the prior art is provided for another embodiment of the present application;

[0028] Figure 3 A structure diagram of a battery pack voltage sampling circuit is provided for an embodiment of the present application;

[0029] Figure 4 A structure diagram of a second connecting member is provided for an embodiment of the present application;

[0030] Figure 5 A structure diagram of a battery pack voltage sampling circuit is provided for another embodiment of the present application.

[0031] In the figure: 1-battery module; 2-electric cell; 3-first connecting member; 4-first sampling unit; 5-second sampling unit; 6-control unit; 7-first sampling channel; 8-second sampling channel; 9-target electric cell; 10-second connecting member; 11-BMU; 12-BCU. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work also belong to the scope of protection of the present application.

[0033] In the prior art, the energy storage components in an electrochemical energy storage system can contain multiple levels. Generally, a plurality of electric cells are connected in series to form a battery module, then one or more battery modules are connected in series and packaged as a battery pack, a plurality of battery packs are further connected in series to form a battery cluster, and then a plurality of battery clusters are connected in parallel to obtain an energy storage battery array. Among them, the electric cells in the battery module are connected in series through aluminum tabs between the electric cells, and the battery modules composed of a plurality of electric cells are connected through copper bars. The performance of the entire electrochemical energy storage system in the electrochemical energy storage system is generally determined by the worst-performing electric cell among all the series and parallel connected electric cells, and the performance of each electric cell will change after the electrochemical energy storage system is used for a period of time, thereby affecting the performance of the entire electrochemical energy storage system.

[0034] Therefore, the voltage of each battery cell is usually monitored in real time. However, in reality, the aluminum strips connecting the battery cells and the copper busbars connecting the two battery modules have internal resistance. In the actual monitoring process of the battery cells, the internal resistance of the copper busbar connected between the two battery cells is relatively large, which will affect the monitoring voltage result of the previous battery cell connected to the copper busbar, resulting in a large deviation between the monitoring result and the actual voltage of the battery cell. In addition, the internal resistance of the aluminum strips between the battery cells is relatively small and basically the same, and the impact on the collected battery cell voltage is basically the same and can be ignored. The copper busbar between the battery modules can be equivalently regarded as a series resistor between the two battery modules. The resistance of this resistor is much larger than the internal resistance of the aluminum strips between the battery cells, and has a greater impact on the voltage of the battery cells connected to the copper busbar in the two battery modules. Figure 1 and Figure 2 As shown in the figure, sampling point A is set at the end of the previous cell connected to the copper busbar away from the copper busbar, and sampling point B is set between the next cell connected to the copper busbar and the copper busbar, so that the voltage U A And the voltage U at sampling point B B The voltage difference U AB As the voltage of the first of the two battery cells connected to the copper busbar.

[0035] like Figure 1 As shown, when the energy storage component is charging, the direction of the charging current flows from the positive electrode to the negative electrode of the battery cell. At this time, the voltage of the first battery cell of the two batteries connected to the copper busbar is U0, and the voltage of the copper busbar connected to it is U R , according to the voltage U at sampling point A A And the voltage U at sampling point B B Get U AB As the voltage of the first cell of the two cells connected to the copper busbar, its value is the voltage U0 of the cell and the voltage U R The sum of the collected cell voltage is U0+U R .

[0036] like Figure 2 As shown, when the energy storage component is discharging, the direction of the discharge current flows from the negative electrode of the battery cell to the positive electrode. At this time, the voltage of the first battery cell of the two batteries connected to the copper busbar is U0, and the voltage of the copper busbar connected to it is U R , according to the voltage U at sampling point A A And the voltage U at sampling point B B Get U AB As the voltage of the first cell of the two cells connected to the copper busbar, its value is the voltage U0 of the cell and the voltage U R The difference between the two, that is, the voltage of the collected battery cell is U0-U R .

[0037] According to the above content, when sampling the voltage, the collected voltage of the battery cell is greater than the actual voltage of the battery cell during charging, which causes the electrochemical energy storage system to think that the battery cell has been charged to the threshold and ends charging early. When discharging, the collected voltage of the battery cell is less than the actual voltage of the battery cell, which causes the electrochemical energy storage system to think that the stored energy of the battery cell has been discharged, thereby ending discharge early, so that the collected voltage value is not the true voltage value of the battery cell, that is, it is too high when charging and too low when discharging. This will cause the battery cell to be mistakenly regarded as the battery cell with the worst performance, affecting the performance of the entire energy storage system. Therefore, it is necessary to accurately collect the voltage of the battery cell, which is the target battery cell 9 mentioned below in this application.

[0038] In order to solve the above problems, the present application provides a battery pack voltage sampling circuit, and the specific solution is as follows.

[0039] Figure 3 This is a battery pack voltage sampling circuit according to an embodiment of the present application. Figure 3 As shown, the battery pack voltage sampling circuit is used to sample the voltage of each battery cell 2 in the battery pack. The battery pack includes N battery modules 1 connected in series, where N is an integer greater than or equal to 2. The battery module 1 includes M battery cells 2 connected in series, where N and M are integers greater than or equal to 2. Every two adjacent battery modules 1 are connected in series via a first connector 3.

[0040] The battery pack voltage sampling circuit includes: K first sampling units 4, a second sampling unit 5 and a control unit 6, where K is an integer greater than or equal to 1 and less than N. The first sampling unit 4 includes at least a first sampling channels 7, where a is an integer greater than M. The second sampling unit 5 includes at least N-1 second sampling channels 8;

[0041] K first sampling units 4 are connected to both ends of each battery cell 2 in the N battery modules 1 through the first sampling channels 7;

[0042] The second sampling channel 8 is connected between the first connector 3 and the target cell 9 , and the target cell 9 is the last cell 2 in the previous battery module 1 of the two adjacent battery modules 1 connected by the first connector 3 ;

[0043] The control unit 6 is configured to obtain the collected voltages through the first sampling channels 7 and the second sampling channels 8 , and obtain the voltage of each battery cell 2 in each battery module 1 according to the collected voltages.

[0044] When the number a of the first sampling channels 7 of one first sampling unit 4 is greater than the number M of the battery cells 2 in the battery module 1, the first sampling unit 4 samples across the battery module 1. And the first connecting piece 3 is connected in series between two battery modules 1, and the voltage affected by the first connecting piece 3 is the voltage of the last battery cell 2 in the N-1 battery modules 1 except the last battery module in the battery pack. Therefore, the last battery cell 2 in the N-1 battery modules 1 except the last battery module 1 in the battery pack is called the target battery cell 9, so it can be known that the number of the first connecting pieces 3 in the battery pack is N-1, and the number of the target battery cells 9 is also N-1.

[0045] The two ends of each battery cell 2 are connected to the first sampling channel 7, wherein one end of the target battery cell 9 (i.e. between the target battery cell 9 and the battery cell 2 connected in series with the target battery cell 9 in the same battery module 1) is connected to the first sampling channel 7, and the voltage collected by the first sampling channel 7 is U1; the other end of the target battery cell 9 (i.e. between the target battery cell 9 and the first battery cell 2 connected in series with the target battery cell 9 through the first connecting piece 3 in the next battery module 1) is connected to the first sampling channel 7, and the first sampling channel 7 is close to the first battery cell 2 of the next battery module 1 and is used to collect the voltage U2 between the first connecting piece 3 and the first battery cell 2. The second sampling channel 8 is arranged between the target battery cell 9 and the first connecting piece 3, and the second sampling channel 8 is close to the target battery cell 9 and is used to collect the voltage U3 between the target battery cell 9 and the first connecting piece 3. Therefore, the number of the second sampling channels 8 arranged in the application is at least N-1. Compared with the prior art that obtains the voltage of the target battery cell 9 according to U1 and U2, the application obtains the voltage of the target battery cell 9 according to U1 and U3, and U2 is closer to the actual voltage value of the other end of the target battery cell 9 than U3.

[0046] The first sampling unit 4 collects the voltages of the one ends of the N-1 target battery cells 9 through the N-1 first sampling channels 7 and sends them to the control unit 6, and the second sampling unit 5 collects the voltages of the other ends of the N-1 target battery cells 9 through the N-1 second sampling channels 8 and sends them to the control unit 6, so that the control unit 6 obtains the voltages of the N-1 target battery cells 9, and the first sampling unit 4 sends the voltages of the other battery cells 2 collected by the remaining first sampling channels 7 to the control unit 6, so that the control unit 6 obtains the voltages of the other battery cells 2.

[0047] The working process of the above-mentioned battery pack voltage sampling circuit is as follows:

[0048] At each sampling time, the N-1 second sampling channels 8 in the first sampling unit 4 collect the voltage of one end of the target battery cell 9 in the N-1 battery modules 1 and send it to the control unit 6, and the N-1 second sampling channels 8 in the second sampling unit 5 collect the voltage of the other end of the target battery cell 9 in the N-1 battery modules 1 and send it to the control unit 6, and the remaining first sampling channels 7 in the K first sampling units 4 collect the voltage across the remaining battery cells 2 in the battery pack and send it to the control unit 6;

[0049] At each sampling time, the control unit 6 obtains the voltage of the N-1 target battery cells 9 according to the voltage of one end of the target battery cell 9 collected by the N-1 first sampling channels 7 and the voltage of the other end of the target battery cell 9 collected by the N-1 second sampling channels 8, that is, the voltage of the target battery cell 9 is obtained by subtracting the voltage collected by the first sampling channel 7 from the voltage collected by the second sampling channel 8 connected to the target battery cell 9, and the control unit 6 obtains the voltage of the remaining battery cells 2 according to the voltage across each battery cell 2 collected by the remaining first sampling channels 7 at each sampling time, that is, the voltage of each battery cell 2 is obtained by subtracting the voltage collected by the first sampling channel 7 connected to one end of the battery cell 2 from the voltage collected by the first sampling channel 7 connected to the other end of the battery cell 2. Thus, the control unit 6 can obtain the voltage of each battery cell 2 in the battery pack.

[0050] In this embodiment, the voltage across each battery cell 2 in the N battery modules 1 is collected by the first sampling channels 7 in the K first sampling units 4 and sent to the control unit 6, and the voltage between the target battery cell 9 and the first connecting member 3 in the N-1 battery modules 1 is collected by the N-1 second sampling channels 8 in the second sampling unit 5 and sent to the control unit 6, and the voltage of each battery cell 2 in the battery pack is obtained by the control unit 6. Based on the existing first sampling unit 4 which samples across the battery modules 1, the present application adds the second sampling unit 5 including N-1 second sampling channels 8, and a sampling point is newly arranged between each target battery cell 9 and the first connecting member 3, which is close to the target battery cell 9, and the N-1 second sampling channels 8 are connected to the N-1 sampling points respectively, so as to realize accurate sampling of the voltage of the N-1 target battery cells 9. Without improving the original first sampling unit 4 which samples across the battery modules 1, only by adding the second sampling unit 5, the influence of the first connecting member 3 on the voltage of the target battery cell 9 can be reduced, and the voltage of each battery cell 2 can be more accurately collected, which provides data guarantee for the consistency of the whole system.

[0051] Optionally, as shown in Figure 4 two adjacent battery cells 2 in the battery module 1 are connected in series by the second connecting member 10;

[0052] For each battery module 1, two first sampling channels 7 connected with the two ends of the first battery cell 2 are connected to the first connecting piece 3 and the second connecting piece 10 respectively, the first sampling channel 7 and the second sampling channel 8 connected with the two ends of the target battery cell 9 are connected to the second connecting piece 10 and the first connecting piece 3 respectively, and two first sampling channels 7 connected with the two ends of other battery cells 2 are connected to two second connecting pieces 10 respectively.

[0053] The resistance of the first connecting piece 3 is greater than the resistance of the second connecting piece 10, and the difference between the resistance of the first connecting piece 3 and the resistance of the second connecting piece 10 is greater than a preset value.

[0054] The second connecting piece 10 is connected between two adjacent battery cells 2 in the battery module 1, the first sampling channel 7 is connected with the second connecting piece 10, and the second sampling channel 8 is connected with the first connecting piece 3.

[0055] When the difference between the resistance of the first connecting piece 3 and the resistance of the second connecting piece 10 is greater than a preset value, the preset value is generally twice the resistance of the second connecting piece 10. When sampling across the battery module, the first connecting piece 3 will divide the voltage of the target battery cell 9 because of its large internal resistance, so it has the above influence on the voltage collection of the target battery cell 9. The internal resistance of each second connecting piece 10 is basically the same, and the influence on the voltage of the battery cell 2 is also basically the same, so when sampling the battery cell 2 alone, the influence of the second connecting piece 10 on the collected voltage of the battery cell 2 can be ignored.

[0056] At each sampling moment, in each of the N-1 battery modules 1, the first sampling channel 7 collects the voltage on the second connecting piece 10 connected with the target battery cell 9, the second sampling channel 8 collects the voltage on the first connecting piece 3 connected with the target battery cell 9, the first sampling unit 4 and the second sampling unit 5 respectively send the voltage collected by the first sampling channel 7 and the voltage collected by the second sampling channel 8 to the control unit 6, and the control unit 6 obtains the voltage of the target battery cell 9 according to the difference between the voltage collected by the first sampling channel 7 and the voltage collected by the second sampling channel 8.

[0057] At each sampling moment, in each of the N-1 battery modules 1, the first sampling channel 7 collects the voltage on the second connecting piece 10 connected with the target battery cell 9, the second sampling channel 8 collects the voltage on the first connecting piece 3 connected with the target battery cell 9, the first sampling unit 4 and the second sampling unit 5 respectively send the voltage collected by the first sampling channel 7 and the voltage collected by the second sampling channel 8 to the control unit 6, and the control unit 6 obtains the voltage of the target battery cell 9 according to the difference between the voltage collected by the first sampling channel 7 and the voltage collected by the second sampling channel 8.

[0058] At each sampling time, in each battery module 1, each first sampling channel 7 collects the voltage on the second connecting piece 10 connected with each battery cell 2, and the first sampling unit 4 sends the voltage collected by each first sampling channel 7 to the control unit 6, and the control unit 6 obtains the voltage of the other battery cell 2 according to the voltage difference between the two ends of the other battery cell 2 collected by each first sampling channel 7.

[0059] Optionally, the first sampling channel 7 or the second sampling channel 8 is connected at the two ends of the battery cell 2 through a connecting line and a voltage sensor.

[0060] Among them, the voltage sensor is arranged on the first connecting piece 3 and the second connecting piece 10, each voltage sensor collects the voltage on each second connecting piece 10 and the voltage on each first connecting piece 3, the first sampling channel 7 obtains the voltage of the second connecting piece 10 collected by the voltage sensor through a connecting line, and the second sampling channel 8 obtains the voltage between the target battery cell 9 and the first connecting piece 3 collected by the voltage sensor through a connecting line.

[0061] By arranging the connecting line and the voltage sensor, the sampling unit can accurately obtain the voltage between the two ends of the battery cell through the sampling channel, and the accuracy of the collected battery cell voltage is improved.

[0062] Optionally, as shown in Figure 5 K first sampling units 4 are K first sampling chips;

[0063] The second sampling unit 5 is a second sampling chip.

[0064] Among them, the first sampling chip collects the voltage on the first connecting piece 3 and the voltage on the second connecting piece 10 connected with each battery cell in each battery module 1 through the first sampling channel 7 arranged in the first sampling chip, and sends the voltage on the first connecting piece 3 and the second connecting piece 10 collected by each first sampling channel 7 to the control unit 6.

[0065] The second sampling chip collects the voltage between the target battery cell 9 and the first connecting piece 3 in N-1 battery modules 1 through the second sampling channel 8 arranged in the second sampling chip, and sends the collected voltage to the control unit 6.

[0066] The control unit 6 obtains the voltage of each battery cell 2 according to the voltage collected by each first sampling channel 7 of K first sampling chips and the voltage collected by each second sampling channel 8 of the second sampling chip.

[0067] On the basis of the existing K sampling chips sampling the cell module voltage across the battery modules in the battery pack according to the prior art, by adding a sampling chip to collect the voltage between the target cell 9 and the first connecting piece 3, the purpose of accurately collecting the voltage of the target cell 9 is achieved, and the problem of inaccurate collection of the voltage of the target cell 9, thereby affecting the performance of the entire energy storage system, is solved.

[0068] Further, the second sampling unit 5 and the control unit 6 are integrated in the above-mentioned second sampling chip. Among them, the K first sampling chips send the collected voltage to the second sampling chip, and the second sampling chip obtains the voltage of each cell 2 according to the voltage collected by each first sampling channel 7 of the K first sampling chips and the voltage collected by each second sampling channel 8 of the second sampling chip.

[0069] Integrating the control unit 6 and the second sampling unit 5 in the same sampling chip can avoid increasing the number of electronic components used.

[0070] Optionally, the K first sampling units 4 are K first sampling chips, and K*a is less than N*M+N and greater than N*M+1;

[0071] The second sampling unit 5 multiplexes K*a-(N*M+1) first sampling channels 7 in the first sampling unit 4; and N*M+N-K*a second sampling channels 8 in the second sampling unit 5 are integrated in the second sampling chip.

[0072] Among them, K*a is the number of sampling channels contained in the K first sampling chips, N*M+1 is the number of first sampling channels 7 required for collecting N battery modules 1, and the number of second sampling channels 8 required for collecting N battery modules 1 is N-1. In order to accurately collect the voltage of the target cell 9, the total number of required sampling channels is the sum of the number of first sampling channels 7 and the number of second sampling channels 8, which is N-1+N*M+1, that is, N*M+N.

[0073] Among them, when K*a is less than N*M+N and greater than N*M+1, it means that after N*M+1 of the sampling channels in the K first sampling chips are used for N battery modules, there are still K*a-(N*M+1) sampling channels left unused. In order to improve the utilization rate of the first sampling chip and save economic cost, the remaining unused sampling channels can be multiplexed as second sampling channels 8 to detect the voltage between the target cell 9 and the first connecting piece 3. Since the number of second sampling channels 8 corresponding to N battery modules is N-1, after multiplexing the remaining unused sampling channels, N*M+N-K*a second sampling channels 8 are still needed, which are integrated in the second sampling chip.

[0074] By multiplexing the remaining first sampling channels 7 in the first sampling chip as the second sampling channels 8, the number of required second sampling channels 8 in the second sampling chip is reduced, the second sampling chip with fewer sampling channels is selected, the utilization rate of the first sampling channels 7 is improved, and the cost is reduced.

[0075] Optionally, as shown in Figure 5 K first sampling chips are respectively integrated in K battery module management units (English full name: Battery Management Unit, English abbreviation: BMU) 11 of the battery pack, and the second sampling chip is integrated in a battery cluster management unit (English full name: Battery Control Unit, English abbreviation: BCU) 12 of the battery pack.

[0076] Among them, the control unit 6 is integrated in the BCU 12, the K BMUs 11 send the voltages collected by the first sampling chips in them to the BCU 12, and the BCU 12 collects the voltages through the second sampling chip, so that the BCU 12 obtains the accurate voltages of the battery cells 2 according to the above-mentioned voltages.

[0077] On the basis of integrating the K first sampling chips in the K BMUs 11, the voltage between the target battery cell 9 and the first connecting piece 3 is collected by using the second sampling chip integrated in the BCU 12, so that the purpose of obtaining the accurate voltage of the target battery cell 9 by the BCU 12 can be achieved only by improving the BCU 12 without improving the original BMU 11 in the battery pack.

[0078] In another possible implementation manner, the K first sampling chips and the second sampling chip are respectively integrated in K+1 BMUs 11.

[0079] Among them, the control unit 6 is integrated in the BCU 12, the K BMUs 11 send the voltages collected by the first sampling chips in them to the BCU 12, and the BCU 12 collects the voltages through the second sampling chip, so that the BCU 12 obtains the accurate voltages of the battery cells 2 according to the above-mentioned voltages.

[0080] All the voltages received by the K+1 BMUs 11 are obtained, so that the voltages of the battery cells 2 are obtained, and only one BMU 11 needs to be added on the basis of the K BMUs 11 in the original battery pack, so that the accurate voltages of the target battery cells 9 in the BCU 12 can be obtained with the minimum economic cost.

[0081] Optionally, the K first sampling units 4 are K first sampling chips, and K*a is greater than or equal to N*M+N;

[0082] The second sampling unit 5 is integrated on one of the K first sampling chips.

[0083] When the number of the remaining sampling channels is greater than or equal to the number of the second sampling channels 8 of the required second sampling unit 5, that is, when K*a is greater than or equal to N*M+N, the second sampling unit 5 is integrated on the first sampling chip with the remaining sampling channels among the K first sampling chips, so as to use the remaining unused sampling channels of the first sampling chip as the second sampling channels 8, and these second sampling channels 8 collect the voltage between the target battery cell 9 and the first connecting piece 3 and the voltage collected by the first sampling channels 7 of the first sampling chip, and then send them to the BCU 12 through the first sampling chip.

[0084] Further, the unused sampling channels of the first sampling chip are multiplexed by all the second sampling channels 8, so that the precise sampling of the target battery cell 9 is realized without adding new sampling chips, and the BCU 12 can accurately obtain the voltage of each battery cell 2.

[0085] Optionally, the K first sampling chips are integrated in the K BMUs 11 of the battery pack respectively.

[0086] Among the K first sampling chips, there are at least N*M+N first sampling channels 7, wherein N*M+N is the sampling channel actually collecting the voltage, N*M+1 of which is the first sampling channel 7, and the other N-1 first sampling channels 7 are the second sampling channels 8.

[0087] The K first sampling chips send the voltage collected by the N*M+N sampling channels to the K BMUs 11, and the K BMUs 11 send the collected voltage to the BCU 12, so that the remaining unused first sampling channels in the existing BMU 11 are multiplexed, and the voltage of each battery cell 2 is accurately obtained with the minimum economic cost without adding new BMU.

[0088] Finally, it should be noted that the contents not described in the technical solutions of the present application can be realized by using the existing technology. In addition, the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that; it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery pack voltage sampling circuit, comprising: The application relates to a battery pack voltage sampling circuit. The battery pack voltage sampling circuit comprises K first sampling units, a second sampling unit and a control unit, K is an integer greater than or equal to 1 and smaller than N, the first sampling unit comprises at least a first sampling channel, a is an integer greater than M, the second sampling unit comprises at least N-1 second sampling channels. The K first sampling units are connected to both ends of each cell in the N battery modules through the first sampling channels. The second sampling channel is connected between the first connecting element and a target cell, and the target cell is the last cell in the first battery module connected to the first connecting element. The control unit is used for acquiring the collected voltage through each first sampling channel and each second sampling channel, and obtaining the voltage of each cell in each battery module according to the collected voltage.

2. The battery pack voltage sampling circuit of claim 1, wherein, The first connecting element has a resistance value greater than that of the second connecting element, and the difference between the resistance values of the first connecting element and the second connecting element is greater than a preset value. The K first sampling units are K first sampling chips. The second sampling unit is a second sampling chip, or the second sampling unit and the control unit are integrated in the second sampling chip.

3. The battery pack voltage sampling circuit of claim 1, wherein, The K first sampling units are K first sampling chips, and K*a is smaller than N*M+N and greater than N*M+1. The second sampling unit multiplexes K*a-(N*M+1) first sampling channels in the first sampling unit; and N*M+N-K*a second sampling channels in the second sampling unit are integrated in a second sampling chip.

4. The battery pack voltage sampling circuit of claim 1, wherein, The K first sampling chips are respectively integrated in K battery module management units (BMUs) of the battery pack, and the second sampling chip is integrated in a battery cluster management unit (BCU) of the battery pack. The K first sampling chips and the second sampling chip are respectively integrated in K+1 BMUs.

5. The battery pack voltage sampling circuit of claim 3, wherein, The K first sampling units are K first sampling chips, and K*a is greater than or equal to N*M+N. The second sampling unit is integrated in one of the K first sampling chips.

6. The battery pack voltage sampling circuit of claim 1, wherein, The K first sampling chips are respectively integrated in K BMUs of the battery pack. The first sampling unit or the second sampling channel is connected to both ends of the cell through a connecting line and a voltage sensor.

7. The battery pack voltage sampling circuit of claim 6, wherein, ​ 8. The battery pack voltage sampling circuit of any one of claims 1-7, wherein, ​

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