Battery cell voltage sampling circuit

Abstract

The utility model provides a battery cell voltage sampling circuit, which comprises a sampling unit, a selection unit, N + 1 first sampling lines and a second sampling line, N is an integer greater than or equal to 1, the sampling unit comprises N + 1 sampling channels, and two adjacent battery modules are connected in series through a first connecting piece; the N + 1 first sampling lines are correspondingly connected to the two ends of N battery cells which are sequentially connected in series in two adjacent battery modules, and the N + 1 first sampling lines are connected with the N + 1 sampling channels in the sampling unit; one end of the second sampling line is connected to one end, connected with the first connecting piece, of the target cell, and the other end of the second sampling line is connected with the selection unit. According to the method and the device, the selection unit and the second sampling line are additionally arranged on the basis of not changing the number of the existing sampling channels, so that the target battery cell is independently sampled, the voltage of each battery cell is accurately acquired, and the state of each battery cell is monitored.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a battery cell voltage sampling circuit. Background Art

[0002] In recent years, electrochemical energy storage technology has gradually replaced hydroelectric energy storage and become the mainstream choice in today's energy storage field. Energy storage components represented by electrochemical energy storage technology are constructed by connecting multiple battery cells in series to form a battery module. One or more battery modules are then connected in series and packaged into a battery pack. Multiple battery packs are further connected in series to form a battery cluster. Battery management systems are typically used for monitoring and management of energy storage components.

[0003] In a battery management system, the voltage of each battery cell is usually sampled through the sampling channel of the sampling unit through the battery module management unit, and the obtained sampling data is sent to the battery management system, which controls the battery system based on the received sampling data. Generally, a large resistance element (such as a copper busbar or an aluminum busbar) is passed between multiple battery modules of a battery system. However, when current flows through the large resistance element, a large difference in voltage will occur across the large resistance element. When the battery module management unit samples the voltage of each battery cell, the number of battery cells in each battery module cannot correspond one-to-one to the number of sampling channels of the sampling unit in the battery module management unit. Usually, the number of sampling channels of the sampling unit will be left over. In actual application, in order to reduce costs, cross-module sampling of a certain sampling unit will occur. At this time, the large resistance element between the two battery modules affects the sampled voltage of the battery cell connected to the large resistance element, so that the voltage of the battery cell collected by the sampling unit is inaccurate, affecting the normal operation of the energy storage component. Utility Model Content

[0004] The present application provides a voltage cell sampling circuit to solve the technical problems existing in the above-mentioned background technology.

[0005] The present application provides a voltage cell sampling circuit for collecting cell voltages of two adjacent battery modules, comprising: a sampling unit, a selection unit, N+1 first sampling lines and a second sampling line, where N is an integer greater than or equal to 1, the sampling unit including N+1 sampling channels, and the two adjacent battery modules are connected in series via a first connector;

[0006] The N+1 first sampling lines are correspondingly connected to both ends of the N battery cells connected in series in the two adjacent battery modules, and the N+1 first sampling lines are connected to the N+1 sampling channels in the sampling unit;

[0007] One end of the second sampling line is connected to one end of the target battery cell connected to the first connector, and the other end of the second sampling line is connected to the selection unit, wherein one target first sampling line among the N+1 first sampling lines is connected to one target sampling channel in the sampling unit through the selection unit, and the target battery cell is the last battery cell of the previous battery module;

[0008] The selection unit is configured to send the voltage collected by the target first sampling line to the sampling unit through the target sampling channel at a first sampling moment, and send the voltage collected by the second sampling line to the sampling unit through the target sampling channel at a second sampling moment;

[0009] The sampling unit is configured to receive N+1 voltages through N+1 sampling channels, and obtain the voltages of the N battery cells based on the N+1 voltages, wherein the voltage of the target battery cell is obtained based on the second voltage collected at the first sampling moment and the second sampling moment, the first voltage being the voltage collected by the first sampling line connected to the other end of the target battery cell, and the second voltage being the voltage collected by the second sampling line.

[0010] Optionally, two adjacent battery cells in the battery module are connected in series via a second connector;

[0011] The N first sampling lines are connected to the N second connecting members respectively, and the remaining first sampling line is connected to the connection point between the first battery cell of the next battery module and the first connecting member;

[0012] The second sampling line is connected to the connection point between the target battery cell and the first connecting member;

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

[0014] Optionally, the target first sampling line of the cell voltage sampling circuit connected to the target sampling channel through the selection unit is connected to a connection point between the first cell of the next battery module and the first connector.

[0015] Optionally, the sampling unit further includes a register, the register is connected to the selection unit, and the register is used to store the selection instruction sent by the sampling unit;

[0016] The selection unit is configured to obtain a selection instruction stored in the register, and send the voltage collected by the target first sampling line to the sampling unit through the target sampling channel according to the selection instruction at a first sampling moment, and send the voltage collected by the second sampling line to the sampling unit through the target sampling channel according to the selection instruction at a second sampling moment.

[0017] Optionally, the selection instruction stored in the register is a parity flag;

[0018] When the parity flag is odd, it is used to instruct the selection unit to send the voltage collected by the target first sampling line to the sampling unit through the target sampling channel; when the parity flag is even, it is used to instruct the selection unit to send the voltage collected by the second sampling line to the sampling unit through the target sampling channel, or,

[0019] When the parity flag is even, it is used to instruct the selection unit to send the voltage collected by the target first sampling line to the sampling unit through the target sampling channel. When the parity flag is odd, it is used to instruct the selection unit to send the voltage collected by the second sampling line to the sampling unit through the target sampling channel.

[0020] Optionally, the selection unit is a switch unit;

[0021] At the first sampling moment, the target first sampling line is connected to the target sampling channel via the switch unit, and the second sampling line is disconnected from the target sampling channel via the switch unit;

[0022] At the second sampling moment, the target first sampling line is connected to the target sampling channel via the switch unit, and the second sampling line is connected to the target sampling channel via the switch unit.

[0023] Optionally, the switch unit includes a single-pole double-throw switch, a first end of the single-pole double-throw switch is connected to the target first sampling line connected to the target battery cell, a second end of the single-pole double-throw switch is connected to the second sampling line, and a third end of the single-pole double-throw switch is connected to the target sampling channel;

[0024] When the first end is connected to the third end and the second end is disconnected from the third end, the target first sampling line is connected to the target sampling channel, and the second sampling line is disconnected from the target sampling channel;

[0025] When the first end is disconnected from the third end and the second end is connected to the third end, the target first sampling line is disconnected from the target sampling channel, and the second sampling line is connected to the target sampling channel.

[0026] Optionally, the switch unit includes a relay, the relay includes a coil, a normally open contact, and a normally closed contact, the coil of the relay is connected to the sampling unit, the normally closed contact of the relay is connected to the target first sampling line, and the normally open contact of the relay is connected to the second sampling line;

[0027] When the coil loses power, the normally closed contact closes, the normally open contact opens, the target first sampling line is connected to the target sampling channel, and the second sampling line is disconnected from the target sampling channel;

[0028] When the coil is energized, the normally closed contact is opened, the normally open contact is closed, the connection between the target first sampling line and the target sampling channel is disconnected, and the connection between the second sampling line and the target sampling channel is connected.

[0029] Optionally, the selection unit is a multiplexer, a first input terminal of the multiplexer is connected to the target first sampling line, a second input terminal is connected to the second sampling line, and an output terminal is connected to the target sampling channel;

[0030] The multiplexer is used to output the voltage inputted from the first input terminal through the output terminal at a first sampling moment, and to output the voltage inputted from the second input terminal through the output terminal at a second sampling moment.

[0031] Optionally, the sampling unit further includes a timer, which is connected to the selection unit. The selection unit is configured to send the voltage collected by the target first sampling line to the sampling unit through the target sampling channel at a first sampling moment, and send the voltage collected by the second sampling line to the sampling unit through the target sampling channel at a second sampling moment according to the timing of the timer.

[0032] In this embodiment, the voltages across N battery cells are collected via N+1 first sampling lines, and the voltage of a target battery cell is collected via a second sampling line. At a first sampling moment, the voltage collected by the target first sampling line is sent to the sampling unit via a selection unit. At a second sampling moment, the voltage collected by the second sampling line is sent to the sampling unit by the selection unit. The voltage of the target battery cell is obtained by combining the voltage collected by the second sampling line with the voltages collected by the target first sampling line and the N+1 first sampling lines. Based on the existing number of sampling channels, the present application enables individual sampling of the target battery cell by adding a selection unit and a second sampling line. The target sampling channel connected to the added selection unit is the sampling channel connected to any one of the first sampling lines. The first sampling line and the second sampling line are connected to the selection unit so that the first sampling line and the second sampling line share a target sampling channel. Thus, without modifying the original collection unit, only one selection unit and one second sampling line need to be added to individually obtain the voltage of the target battery cell, thereby ensuring that the sampling unit can accurately collect the voltage of each battery cell and monitor the status of each battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0034] Figure 1 A schematic diagram of the structure of cell voltage sampling during charging in the prior art provided in one embodiment of the present application;

[0035] Figure 2 A schematic diagram of the structure of cell voltage sampling during discharge in the prior art provided by another embodiment of the present application;

[0036] Figure 3 A schematic diagram of the structure of a cell voltage sampling provided in an embodiment of the present application;

[0037] Figure 4 A schematic diagram of the structure of cell voltage sampling provided in another embodiment of the present application;

[0038] Figure 5 A schematic diagram of the structure of cell voltage sampling provided in another embodiment of the present application;

[0039] Figure 6 A schematic diagram of the structure of cell voltage sampling provided in yet another embodiment of the present application;

[0040] In the figure: 1-sampling unit; 2-selection unit; 3-first sampling line; 4-second sampling line; 5-sampling channel; 6-battery cell; 7-target battery cell; 8-target first sampling line; 9-target sampling channel; 10-first connector; 11-second connector; 12-register; 13-multiplexer; 14-timer; 15-battery module. DETAILED DESCRIPTION

[0041] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application are clearly and completely described below. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts also fall within the scope of protection of this application.

[0042] In the prior art, the energy storage components in an electrochemical energy storage system may include multiple levels. Generally, multiple battery cells are connected in series to form a battery module, and then one or more battery modules are connected in series and packaged into a battery pack. Multiple battery packs are further connected in series to form a battery cluster, and then multiple battery clusters are connected in parallel to obtain an energy storage battery array. Among them, the battery cells in the battery module are connected in series through aluminum tabs, and the battery modules composed of multiple battery cells are connected by copper bars. In the entire electrochemical energy storage system, the performance of the entire system is generally determined by the battery cell with the worst performance among all the battery cells connected in series and parallel. After the electrochemical energy storage system has been used for a period of time, the performance of each battery cell will change, thereby affecting the performance of the entire electrochemical energy storage system.

[0043] Therefore, the voltage of each battery cell is usually monitored in real time. However, the aluminum strips connecting the battery cells and the copper busbars connecting the two battery modules have internal resistance. During the actual monitoring 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 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 regarded as an equivalent 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 UAB As the voltage of the first of the two battery cells connected to the copper busbar.

[0044] 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 .

[0045] 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 .

[0046] 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 7 mentioned below in this application.

[0047] In order to solve the above problems, the present application provides a cell voltage sampling circuit, and the specific solution is as follows.

[0048] Figure 3This is a cell voltage sampling circuit according to an embodiment of the present application, which is used to collect the cell voltages of at least two adjacent battery modules 15. This application takes the cell voltage sampling of two adjacent battery modules 15 as an example, and the cell voltage sampling process of other adjacent battery modules is similar. Figure 3 As shown, the circuit includes: a sampling unit 1, a selection unit 2, N+1 first sampling lines 3 ( Figure 3 In the example, four first sampling lines 3 and four second sampling lines 4 are used, where N is an integer greater than or equal to 1, and the sampling unit 1 includes N+1 sampling channels 5, and two adjacent battery modules 15 are connected in series through a first connector 10;

[0049] N+1 first sampling lines 3 are correspondingly connected to both ends of N battery cells 6 connected in series in two adjacent battery modules 15 , and the N+1 first sampling lines 3 are connected to the N+1 sampling channels 5 in the sampling unit 1 ;

[0050] Among them, a first sampling line 3 is selected from the N+1 first sampling lines 3 as the target first sampling line 8, the sampling channel 5 connected to the target first sampling line 8 in the N+1 sampling channels 5 is called the target sampling channel 9, and the last battery cell 6 of the previous battery module in the two adjacent battery modules 15 is called the target battery cell 7. One end of the second sampling line 4 of the present application is connected to the end of the target battery cell 7 connected to the first connector 10, and the other end of the second sampling line 4 is connected to the selection unit 2, wherein the selection unit 2 is also connected to the target first sampling line and the target sampling channel 9 respectively;

[0051] The selection unit 2 is configured to send the voltage collected by the target first sampling line 8 to the sampling unit 1 through the target sampling channel 5 at the first sampling moment, and to send the voltage collected by the second sampling line 4 to the sampling unit 1 through the target sampling channel 5 at the second sampling moment;

[0052] The sampling unit 1 is used to receive N+1 voltages through N+1 sampling channels 5, and obtain the voltages of N battery cells 6 based on the N+1 voltages, wherein the voltage of the target battery cell 7 is obtained based on the voltages received by the sampling channel 5 connected to the other end of the target battery cell 7 and the target sampling channel 5 at the first sampling moment and the second sampling moment, respectively. The first voltage is the voltage collected by the first sampling line 3 connected to the other end of the target battery cell 7, and the second voltage is the voltage collected by the second sampling line 4.

[0053] The ends of the first sampling line 3 and the second sampling line 4 connected to the battery cell 6 also include a voltage sensor, which is used to sample the voltage of the battery cell 6 and transmit it to the sampling unit 1 through the sampling channels 5 corresponding to the first sampling line 3 and the second sampling line 4. By providing the connecting lines and voltage sensors, the sampling unit can accurately obtain the voltage at both ends of the battery cell through the sampling channels, thereby improving the accuracy of the collected battery cell voltage.

[0054] Among them, the three first sampling lines 3 can be directly connected to the three sampling channels 5 in the sampling unit 1, and the target first sampling line 8 and the second sampling line 4 are connected to the sampling unit 1 through the selection unit 2. The selection unit 2 selects the voltage collected by the target first sampling line 8 or the second sampling line 4 and sends it to the sampling unit 1.

[0055] The working process of the above cell voltage sampling circuit is as follows:

[0056] In one possible implementation, at each sampling moment, the three first sampling lines 3, the target first sampling line 8, and the second sampling line 4 respectively collect the voltages of the four battery cells 6. At the first sampling moment, the three first sampling lines 3 send the collected voltages to the sampling unit 1 via the corresponding sampling channels 5. The target first sampling line 8 and the second sampling line 4 both send the collected voltages to the selection unit 2. The selection unit 2 selects the voltage collected by the target first sampling line 8 and sends it to the sampling unit 1 via the target sampling channel 9. At the first sampling moment, the selection unit 2 does not send the voltage collected by the second sampling line 4 to the sampling unit 1 via the target sampling channel 9. At the second sampling moment, the three first sampling lines 3 send the collected voltages to the sampling unit 1 via the corresponding sampling channels 5. The target first sampling line 8 and the second sampling line 4 both send the collected voltages to the selection unit 2. The selection unit 2 selects the voltage collected by the second sampling line 4 and sends it to the sampling unit 1 via the target sampling channel 9. At the second sampling moment, the selection unit 2 does not send the voltage collected by the target first sampling line 8 to the sampling unit 1 via the target sampling channel 9.

[0057] In another possible implementation, at each sampling moment, the three first sampling lines 3 respectively collect the voltages of the four battery cells 6, and the target first sampling line 8 and the second sampling line 4 alternately collect voltages. At the first sampling moment, the three first sampling lines 3 send the collected voltages to the sampling unit 1 through the corresponding sampling channels 5. The target first sampling line 8 collects the voltage and sends the collected voltage to the selection unit 2. The selection unit 2 sends the voltage collected by the target first sampling line 8 to the sampling unit 1 through the target sampling channel 9. At the first sampling moment, the second sampling line 4 does not collect voltages. At the second sampling moment, the three first sampling lines 3 send the collected voltages to the sampling unit 1 through the corresponding sampling channels 5. The second sampling line 4 collects the voltage and sends the collected voltage to the selection unit 2. The selection unit 2 sends the voltage collected by the second sampling line 4 to the sampling unit through the target sampling channel 9. At the second sampling moment, the target first sampling line 8 does not collect voltages.

[0058] In another possible implementation, at each sampling moment, the four first sampling lines and the second sampling line 4 alternately collect voltages. At the first sampling moment, the three first sampling lines 3 send the collected voltages to the sampling unit 1 via the corresponding sampling channels 5. The target first sampling line 8 collects voltages and sends the collected voltages to the selection unit 2. The selection unit 2 sends the voltage collected by the target first sampling line 8 to the sampling unit 1 via the target sampling channel 9. At the first sampling moment, the second sampling line 4 does not collect voltages. At the second sampling moment, the second sampling line 4 collects voltages and sends the collected voltages to the selection unit 2. The selection unit 2 sends the voltage collected by the second sampling line 4 to the sampling unit 1 via the target sampling channel 9. At the second sampling moment, the four first sampling lines 3 do not collect voltages.

[0059] Based on the above implementations, the sampling unit 1 can obtain the voltage of each battery cell 6 based on the four voltages received through the four sampling channels 5 at the first sampling moment and the one voltage received through the target sampling channel 9 at the second sampling moment. The voltage of the target battery cell 7 is obtained based on the voltage collected by the first sampling line 3 connected to the target battery cell 7 at the first sampling moment and the voltage collected by the second sampling line 4 at the second moment.

[0060] In this embodiment, the voltages at both ends of N battery cells 6 are collected through N+1 first sampling lines 3 and the voltage of the target battery cell 7 is collected through the second sampling line 4. At the first sampling moment, the voltage collected by the target first sampling line 8 is sent to the sampling unit 1 through the selection unit 2. At the second sampling moment, the selection unit 2 sends the voltage collected by the second sampling line 4 to the sampling unit 1. The voltage collected by the second sampling line 4 and the voltage collected by the target first sampling line 8 and the N+1 first sampling lines 3 are used to obtain the voltage of the target battery cell 7. On the basis of the existing number of sampling channels, this application adds a selection unit 2 and a second sampling line 4. It is possible to sample the target battery cell 7 separately, and the target sampling channel 9 connected to the added selection unit 2 is the sampling channel connected to any one of the first sampling lines 3. The first sampling line 3 and the second sampling line 4 are connected to the selection unit 2, so that the first sampling line 3 and the second sampling line 4 share one target sampling channel 9. Therefore, without improving the original sampling unit 1, only one selection unit 2 and one second sampling line 4 need to be added to obtain the voltage of the target battery cell 7 separately, thereby ensuring that the sampling unit 1 can accurately collect the voltage of each battery cell 6 and monitor the status of each battery cell 6.

[0061] In a possible implementation, the N+1 first sampling lines 3 can also be connected to the N+1 sampling channels 5 in the sampling unit 1 through the selection unit 2, so the voltage collected by each first sampling line 3 needs to be sent to the sampling unit 1 through the selection unit 2.

[0062] Among them, at the first sampling moment, the N+1 first sampling lines 3 send the collected voltages to the selection unit 2, and the selection unit 2 sends the received voltages collected by the N+1 first sampling lines 3 to the corresponding sampling unit 1 through the corresponding N+1 sampling channels 5.

[0063] At the second sampling moment, the second sampling line 4 sends the collected voltage to the selection unit 2 , and the selection unit 2 sends the received voltage collected by the second sampling line 4 to the sampling unit 1 through any sampling channel 5 connected to the selection unit 2 .

[0064] In another possible implementation, any one of the N+1 first sampling lines 3 is connected to the second sampling line 4 on the selection unit 2 , and the selection unit 2 enables the second sampling line 4 and the first sampling line 3 to share the sampling channel 5 corresponding to the first sampling line 3 .

[0065] Among them, at the first sampling moment, the N first sampling lines 3 send the collected voltages to the sampling unit 1 through the corresponding sampling channels 5, and any one of the above sampling lines 3 sends the collected voltage to the selection unit 2, and the selection unit 2 sends the received voltage collected by the first sampling line 3 to the corresponding sampling unit 1 through the sampling channel 5 corresponding to the first sampling line 3.

[0066] At the second sampling moment, the second sampling line 4 sends the collected voltage to the selection unit 2 , and the selection unit 2 sends the received voltage collected by the second sampling line 4 to the sampling unit 1 through the sampling channel 5 corresponding to any first sampling line 3 shared by the second sampling line 4 .

[0067] The sampling unit 1 may be a sampling chip, and the selection unit 2 is a component independent of the sampling chip. Alternatively, the sampling unit 1 and the selection unit 2 are integrated into the same sampling chip.

[0068] Optionally, two adjacent battery cells 6 in the battery module 15 are connected in series via a second connector 11 ;

[0069] N first sampling lines 3 are correspondingly connected to N second connectors 11 , and the remaining first sampling line 3 is connected to the connection point between the first battery cell 6 of the next battery module 15 and the first connector 10 ;

[0070] The second sampling line 4 is connected to the connection point between the target battery cell 7 and the first connecting member 10;

[0071] The internal resistance of the first connecting member 10 is greater than the internal resistance of the second connecting member 11 , and the difference between the internal resistance of the first connecting member 10 and the internal resistance of the second connecting member 11 is greater than a preset value.

[0072] When the difference between the resistance of the first connector 10 and the resistance of the second connector 11 is greater than a preset value, which is generally twice the resistance of the second connector 11, when sampling across the battery module 15, the first connector 10, due to its larger internal resistance, will divide the voltage of the target cell 7, thus having the aforementioned impact on the voltage collection of the target cell 7. However, the internal resistance of each second connector 11 is substantially the same, and the impact on the voltage of the cell 6 is also substantially the same. Therefore, when sampling a cell 6 individually, the impact of the second connector 11 on the collected voltage of the cell 6 can be ignored.

[0073] Among them, the second connecting member 11 is connected between two adjacent battery cells 6 in the battery module 15, and N first sampling lines 3 are connected to N second connecting members 11. At each sampling moment, the N first sampling lines 3 send the collected voltage to the sampling unit 1 through N sampling channels 5, so that the sampling unit 1 obtains the voltage of the battery cell 6 connected between the two first sampling lines through the voltage difference collected by each two adjacent first sampling lines 3.

[0074] At the first sampling moment, the selection unit 2 sends the voltage collected by the target first sampling line 8 to the sampling unit 1 through the target sampling channel 9. At the second sampling moment, the selection unit 2 sends the voltage collected by the second sampling line 4 to the sampling unit 1 through the target sampling channel 9. The sampling unit 1 collects the voltage collected by the second sampling line 4 and the voltage collected by the first sampling line 3 connected to the second connector 11 connected to the target battery cell 7. For example, the voltage collected by the first sampling line 3 connected to the second connector 11 connected to the target battery cell 7 is subtracted from the voltage collected by the second sampling line 4 to obtain the voltage of the target battery cell 7.

[0075] Optionally, the cell voltage sampling circuit is connected to the target first sampling line 8 connected to the target sampling channel 5 via the selection unit 2 , and is connected to the connection point between the first cell 6 of the next battery module 15 and the first connector 10 .

[0076] Among them, the second sampling line 4 is fixedly connected between the target battery cell 7 and the first connector 10, and the first sampling line 3 fixedly connected to the connection point between the first battery cell 6 of the subsequent battery module 15 and the first connector 10 is selected as the target first sampling line 8, so the selection unit 2 is connected between the two ends of the first connector 10 and the target sampling channel 9 through the target first sampling line 8 and the second sampling line 4. Since the battery cell 6 sharing a sampling channel 5 with the second sampling line 4 is the first battery cell 6 of the subsequent battery module 15, the battery cell 6 is closest to the target battery cell 7, thereby saving the circuit space of the battery cell voltage sampling circuit.

[0077] Alternatively, see Figure 4, the sampling unit 1 also includes a register 12, the register 12 is connected to the selection unit 2, and the register 12 is used to store the selection instruction sent by the sampling unit 1;

[0078] The selection unit 2 is configured to obtain the selection instruction stored in the register 12, and send the voltage collected by the target first sampling line 8 to the sampling unit 1 through the target sampling channel 5 according to the selection instruction at the first sampling moment, and send the voltage collected by the second sampling line 4 to the sampling unit 1 through the target sampling channel 5 according to the selection instruction at the second sampling moment.

[0079] The register 12 receives the selection instruction sent by the sampling unit 1 and stores the selection instruction so that the selection unit 2 can obtain the selection instruction. The selection unit 2 selects the voltage collected by the target first sampling line 8 and sends it to the sampling unit 1 through the target sampling channel 9 according to the selection instruction obtained at the first sampling moment, and selects the voltage collected by the second sampling line 4 and sends it to the sampling unit 1 through the target sampling channel 9 according to the selection instruction obtained at the second sampling moment. The selection instruction obtained at the first sampling moment is different from the selection instruction obtained at the second sampling moment.

[0080] Optionally, the selection instruction stored in register 12 is a parity flag.

[0081] In one possible implementation, when the selection unit 2 obtains that the parity flag is odd, the selection unit 2 selects the voltage collected by the target first sampling line 8 and sends it to the sampling unit 1 through the target sampling channel 9; when the selection unit 2 obtains that the parity flag is even, the selection unit 2 selects the voltage collected by the second sampling line 4 and sends it to the sampling unit 1 through the target sampling channel 9. At this time, the sampling unit 1 can obtain the voltage of the target battery cell 7 alone.

[0082] In another possible implementation, when the selection unit 2 obtains that the parity flag is even, the selection unit 2 selects the voltage collected by the target first sampling line 8 and sends it to the sampling unit 1 through the target sampling channel 9; when the selection unit 2 obtains that the parity flag is odd, the selection unit 2 selects the voltage collected by the second sampling line 4 and sends it to the sampling unit 1 through the target sampling channel 9. At this time, the sampling unit 1 can obtain the voltage of the target battery cell 7 alone.

[0083] Optionally, the selection unit 2 is a switch unit;

[0084] At the first sampling moment, the target first sampling line 8 is connected to the target sampling channel 5 via the switch unit, and the second sampling line 4 is disconnected from the target sampling channel 5 via the switch unit;

[0085] At the second sampling moment, the target first sampling line 8 is disconnected from the target sampling channel 5 via the switch unit, and the second sampling line 4 is connected to the target sampling channel 5 via the switch unit.

[0086] Among them, at the first sampling moment, when the switch unit connects the target first sampling line 8 to the target sampling channel 9, the switch unit selects to receive the sampling voltage transmitted by the corresponding target first sampling line 8, and sends the voltage collected by the target first sampling line 8 to the sampling unit 1 through the target sampling channel 9. At the same time, the switch unit disconnects the second sampling line 4 from the target sampling channel 9, so that the voltage collected by the second sampling line 4 will not be sent to the target sampling channel 9 through the switch unit.

[0087] At the second sampling moment, when the switch unit connects the second sampling line 4 to the target sampling channel 9, the switch unit selects to receive the voltage collected by the corresponding second sampling line 4, and sends the voltage collected by the second sampling line 4 to the sampling unit 1 through the target sampling channel 9. At the same time, the switch unit disconnects the target first sampling line 8 from the target sampling channel 9, so that the voltage collected by the target first sampling line 8 will not be sent to the target sampling channel 9 through the switch unit.

[0088] Therefore, the present application uses the switch unit to alternately switch to realize sending the voltages collected by the target first sampling line 8 and the second sampling line 4 to the sampling unit 1 through the target sampling channel 9 at different sampling moments.

[0089] Optionally, the switch unit includes a single-pole double-throw switch, a first end of the single-pole double-throw switch is connected to the first sampling line 3 connected to the target battery cell 7, a second end of the single-pole double-throw switch is connected to the second sampling line 4, and a third end of the single-pole double-throw switch is connected to the target sampling channel 5;

[0090] When the first end is connected to the third end and the second end is disconnected from the third end, the target first sampling line 8 is connected to the target sampling channel 5, and the second sampling line 4 is disconnected from the target sampling channel 5;

[0091] When the first end is disconnected from the third end and the second end is connected to the third end, the target first sampling line 8 is disconnected from the target sampling channel 5 , and the second sampling line 4 is connected to the target sampling channel 5 .

[0092] Among them, at the first sampling moment, the single-pole double-throw switch receives the signal from the sampling unit 1, controls the first end to be connected with the third end, and connects the target first sampling line 8 connected with the first end with the target sampling channel 9 connected with the third end, thereby sending the voltage collected by the first sampling line 3 to the sampling unit 1 through the target sampling channel 9. At the same time, since the second end is disconnected from the third end, the single-pole double-throw switch will not send the voltage collected by the second sampling line 4 to the sampling unit 1 through the target sampling channel.

[0093] At the second sampling moment, the single-pole double-throw switch receives the signal from the sampling unit 1, controls the second end to be connected to the third control end, and connects the second sampling line 4 connected to the second end to the target sampling channel 9, thereby sending the voltage collected by the second sampling line 4 to the sampling unit 1 through the target sampling channel 9. At the same time, since the first end is disconnected from the third end, the single-pole double-throw switch will not send the voltage collected by the target first sampling line 8 to the sampling unit 1 through the target sampling channel 9.

[0094] Therefore, the present application can achieve that at different sampling moments, the voltages collected by the target first sampling line 8 and the second sampling line 4 are sent to the sampling unit 1 through the target sampling channel 9, respectively, by alternating between connecting the third end to the first end or connecting the third end to the second end through the single-pole double-throw switch.

[0095] Optionally, the switch unit includes a relay, the relay includes a coil, a normally open contact and a normally closed contact, the coil of the relay is connected to the sampling unit 1, the normally closed contact of the relay is connected to the first sampling line 3, and the normally open contact of the relay is connected to the second sampling line 4;

[0096] When the coil loses power, the normally closed contact closes, the normally open contact opens, the target first sampling line 8 is connected to the target sampling channel 5, and the second sampling line 4 is disconnected from the target sampling channel 5;

[0097] When the coil is energized, the normally closed contact is disconnected, the normally open contact is closed, the connection between the target first sampling line 8 and the target sampling channel 5 is disconnected, and the connection between the second sampling line 4 and the target sampling channel 5 is connected.

[0098] Among them, at the first sampling moment, the sampling unit 1 controls the coil of the relay to lose power, the normally open contact of the relay is disconnected, the normally closed contact of the relay is closed, and the target first sampling line 8 connected to the normally open contact of the relay is connected to the target sampling channel 9. The voltage collected by the target first sampling line 8 is sent to the sampling unit 1 through the target sampling channel 9. Since the normally open contact of the relay is disconnected, the second sampling line 4 will not be connected to the target sampling channel 9, and the sampling unit 1 will not receive the voltage collected by the second sampling line 4.

[0099] At the second sampling moment, the sampling unit 1 controls the coil of the relay to be energized, the normally open contact of the relay is closed, the normally closed contact of the relay is disconnected, and the second sampling line 4 connected to the normally closed contact of the relay is connected to the target sampling channel 9. The voltage collected by the second sampling line 4 is sent to the sampling unit 1 through the target sampling channel 9. Since the normally closed contact of the relay is disconnected, the target first sampling line 8 will not be connected to the target sampling channel 9, and the sampling unit 1 will not receive the voltage collected by the target first sampling line 8.

[0100] Therefore, the present application uses a relay to quickly control the relay coil to alternately energize or de-energize according to the received signal, thereby alternately controlling the contact to close or open, so that at different sampling times, the voltages collected by the target first sampling line 8 and the second sampling line 4 can be sent to the sampling unit 1 through the target sampling channel 9.

[0101] Alternatively, see Figure 5 , the selection unit 2 is a multiplexer 13, a first input end of the multiplexer 13 is connected to the target first sampling line 8, a second input end is connected to the second sampling line 4, and an output end is connected to the target sampling channel 9;

[0102] The multiplexer 13 is configured to output the voltage inputted from the first input terminal through the output terminal at a first sampling moment, and to output the voltage inputted from the second input terminal through the output terminal at a second sampling moment.

[0103] At the first sampling moment, the multiplexer 13 selects the first input terminal to be connected, the target first sampling line 8 connected to the first input terminal is connected to the target sampling channel 9, and the voltage collected by the target first sampling line 8 is sent to the sampling unit 1 through the target sampling channel 9. Because the second input terminal of the multiplexer 13 is disconnected, the second sampling line 4 is disconnected from the target sampling channel 9, and the sampling unit 1 cannot receive the voltage collected by the second sampling line 4.

[0104] At the second sampling moment, the multiplexer 13 selects the second input terminal to be connected, and the second sampling line 4 connected to the second input terminal is connected to the target sampling channel 9. The voltage collected by the second sampling line 4 is sent to the sampling unit 1 through the target sampling channel 9. Because the first input terminal of the multiplexer 13 is disconnected, the target first sampling line 8 is disconnected from the target sampling channel 9, and the sampling unit 1 cannot receive the voltage collected by the target first sampling line 8.

[0105] Therefore, the present application can realize that at different sampling moments, the voltages collected by the target first sampling line 8 and the second sampling line 4 are sent to the sampling unit 1 through the target sampling channel 9 by alternately switching the connection between the first input terminal and the second input terminal through the multiplexer 13.

[0106] Alternatively, see Figure 6 The sampling unit 1 also includes a timer 14, which is connected to the selection unit 2. The selection unit 2 is used to send the voltage collected by the target first sampling line 8 to the sampling unit 1 through the target sampling channel 9 at the first sampling moment according to the timing of the timer 14, and send the voltage collected by the second sampling line 4 to the sampling unit 1 through the target sampling channel 9 at the second sampling moment.

[0107] Among them, according to the timing of the timer 14, at every preset time interval, at the first sampling moment, the selection unit 2 sends the voltage collected by the target first sampling line 8 to the sampling unit 1 through the target sampling channel 9, and at the second sampling moment, the selection unit 2 sends the voltage collected by the second sampling line 4 to the sampling unit 1 through the target sampling channel 9.

[0108] Therefore, the present application sets a timer 14 so that the selection unit 2 automatically and alternately transmits the voltages collected by the target first sampling line 8 and the second sampling line 4 to the sampling unit 1 according to the timing of the timer 14 .

[0109] Finally, it should be noted that any content not described in the technical solution of this application can be implemented using existing technologies. In addition, the above embodiments are only used to illustrate the technical solution of this application, and not to limit it. Although this application has been described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some or all of the technical features therein can be replaced with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solution from the scope of the technical solution of the embodiments of this application.

Claims

1. A cell voltage sampling circuit, characterized in that: Used to collect the cell voltages of two adjacent battery modules, comprising: a sampling unit, a selection unit, N+1 first sampling lines and a second sampling line, where N is an integer greater than or equal to 1, the sampling unit including N+1 sampling channels, and the two adjacent battery modules are connected in series via a first connector; The N+1 first sampling lines are correspondingly connected to both ends of the N battery cells connected in series in the two adjacent battery modules, and the N+1 first sampling lines are connected to the N+1 sampling channels in the sampling unit; One end of the second sampling line is connected to one end of the target battery cell connected to the first connector, and the other end of the second sampling line is connected to the selection unit, wherein one target first sampling line among the N+1 first sampling lines is connected to one target sampling channel in the sampling unit through the selection unit, and the target battery cell is the last battery cell of the previous battery module; The selection unit is configured to send the voltage collected by the target first sampling line to the sampling unit through the target sampling channel at a first sampling moment, and send the voltage collected by the second sampling line to the sampling unit through the target sampling channel at a second sampling moment; The sampling unit is used to receive N+1 voltages through N+1 sampling channels, and obtain the voltages of the N battery cells based on the N+1 voltages, wherein the voltage of the target battery cell is obtained based on a first voltage collected at a first sampling moment and a second voltage collected at a second sampling moment, the first voltage is a voltage collected by a first sampling line connected to the other end of the target battery cell, and the second voltage is a voltage collected by the second sampling line.

2. The cell voltage sampling circuit according to claim 1, characterized in that: Two adjacent battery cells in the battery module are connected in series via a second connector; The N first sampling lines are connected to the N second connecting members respectively, and the remaining first sampling line is connected to the connection point between the first battery cell of the next battery module and the first connecting member; The second sampling line is connected to the connection point between the target battery cell and the first connecting member; The internal resistance of the first connecting member is greater than the internal resistance of the second connecting member, and a difference between the internal resistance of the first connecting member and the internal resistance of the second connecting member is greater than a preset value.

3. The cell voltage sampling circuit according to claim 2, wherein: The target first sampling line connected to the target sampling channel through the selection unit is connected to the connection point between the first battery cell of the next battery module and the first connecting member.

4. The cell voltage sampling circuit according to claim 1, wherein: The sampling unit further includes a register, which is connected to the selection unit and is used to store the selection instruction sent by the sampling unit; The selection unit is configured to obtain a selection instruction stored in the register, and send the voltage collected by the target first sampling line to the sampling unit through the target sampling channel according to the selection instruction at a first sampling moment, and send the voltage collected by the second sampling line to the sampling unit through the target sampling channel according to the selection instruction at a second sampling moment.

5. The cell voltage sampling circuit according to claim 4, characterized in that: The selection instruction stored in the register is a parity flag; When the parity flag is odd, it is used to instruct the selection unit to send the voltage collected by the target first sampling line to the sampling unit through the target sampling channel; when the parity flag is even, it is used to instruct the selection unit to send the voltage collected by the second sampling line to the sampling unit through the target sampling channel, or, When the parity flag is even, it is used to instruct the selection unit to send the voltage collected by the target first sampling line to the sampling unit through the target sampling channel. When the parity flag is odd, it is used to instruct the selection unit to send the voltage collected by the second sampling line to the sampling unit through the target sampling channel.

6. The cell voltage sampling circuit according to any one of claims 1 to 5, characterized in that: The selection unit is a switch unit; At the first sampling moment, the target first sampling line is connected to the target sampling channel via the switch unit, and the second sampling line is disconnected from the target sampling channel via the switch unit; At the second sampling moment, the target first sampling line is connected to the target sampling channel via the switch unit, and the second sampling line is connected to the target sampling channel via the switch unit.

7. The cell voltage sampling circuit according to claim 6, characterized in that: The switch unit includes a single-pole double-throw switch, wherein a first end of the single-pole double-throw switch is connected to the target first sampling line connected to the target battery cell, a second end of the single-pole double-throw switch is connected to the second sampling line, and a third end of the single-pole double-throw switch is connected to the target sampling channel; When the first end is connected to the third end and the second end is disconnected from the third end, the target first sampling line is connected to the target sampling channel, and the second sampling line is disconnected from the target sampling channel; When the first end is disconnected from the third end and the second end is connected to the third end, the target first sampling line is disconnected from the target sampling channel, and the second sampling line is connected to the target sampling channel.

8. The cell voltage sampling circuit according to claim 6, wherein: The switch unit includes a relay, the relay includes a coil, a normally open contact, and a normally closed contact, the coil of the relay is connected to the sampling unit, the normally closed contact of the relay is connected to the target first sampling line, and the normally open contact of the relay is connected to the second sampling line; When the coil loses power, the normally closed contact closes, the normally open contact opens, the target first sampling line is connected to the target sampling channel, and the second sampling line is disconnected from the target sampling channel; When the coil is energized, the normally closed contact is opened, the normally open contact is closed, the connection between the target first sampling line and the target sampling channel is disconnected, and the connection between the second sampling line and the target sampling channel is connected.

9. The cell voltage sampling circuit according to any one of claims 1 to 5, characterized in that: The selection unit is a multiplexer, a first input end of the multiplexer is connected to the target first sampling line, a second input end is connected to the second sampling line, and an output end is connected to the target sampling channel; The multiplexer is used to output the voltage inputted from the first input terminal through the output terminal at a first sampling moment, and to output the voltage inputted from the second input terminal through the output terminal at a second sampling moment.

10. The cell voltage sampling circuit according to any one of claims 1 to 3, characterized in that: The sampling unit further includes a timer, which is connected to the selection unit. The selection unit is configured to send the voltage collected by the target first sampling line to the sampling unit through the target sampling channel at a first sampling moment, and send the voltage collected by the second sampling line to the sampling unit through the target sampling channel at a second sampling moment according to the timing of the timer.

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