Equalization device and method for equalization

Abstract

To provide an equalization device and a method for equalization which can reduce time required to equalize the energy capacities of a plurality of cells.SOLUTION: The equalization device includes: a capacitor X which can be connected to cells adjacent to each other (a cell A and a cell B); a capacitor Y which can be connected to cells 14 adjacent to each other (a cell C and a cell D); and a capacitor Z which can be connected to a cell group a including the cell A and the cell B and to a cell group b including the cell C and the cell D; and a switch SW for switching the connection between the cells 14 and the capacitors X, Y, and Z.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an equalization device and an equalization method for equalizing the energy capacities of a plurality of cells included in a battery pack. [Background technology]

[0002] Patent Document 1 discloses an energy storage device, an energy storage control device, and an energy storage control method that include a plurality of cells connected in series, a series resonant circuit including a reactor and a capacitor, and an energy storage control device that controls the connection state between the cells and the series resonant circuit, and in which the energy storage control device transfers energy between an equal number of cells via the series resonant circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-65795 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology of Patent Document 1, one series resonant circuit equalizes the energy capacity of multiple cells. Therefore, as the number of cells increases, the time required to equalize the energy capacity of the cells increases, leaving room for improvement.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide an equalization device and an equalization method that can shorten the time required to equalize the energy capacities of multiple cells. [Means for solving the problem]

[0006] The equalization device of the first embodiment includes a first power storage unit connectable to adjacent cells of a plurality of cells connected in series, a second power storage unit connectable to adjacent cell groups of the plurality of cells, a detection unit that detects the energy capacity of each of the plurality of cells, and a control unit that controls the connection of the plurality of cells to each of the first power storage unit and the second power storage unit based on the detection result of the detection unit so as to equalize the energy capacities of the plurality of cells.

[0007] The equalization device of the second aspect includes a plurality of first power storage units each connectable to adjacent cells among a plurality of cells connected in series, a second power storage unit each connectable to distant cells among the plurality of cells, a detection unit that detects the energy capacity of each of the plurality of cells, and a control unit that controls the connection of the plurality of cells to each of the first power storage units and the second power storage units based on the detection result of the detection unit so as to equalize the energy capacities of the plurality of cells.

[0008] An equalization method according to a third aspect includes a computer detecting the energy capacity of each of a plurality of cells connected in series, and based on the detection result of the energy capacity, controlling connection of the plurality of cells to each of first storage units connectable to adjacent cells of the plurality of cells and second storage units connectable to groups of adjacent cells of the plurality of cells, thereby performing a process of equalizing the energy capacities of the plurality of cells.

[0009] An equalization method according to a fourth aspect includes a computer detecting the energy capacity of each of a plurality of cells connected in series, and based on the detection result of the energy capacity, controlling connection of the plurality of cells to each of first storage units connectable to adjacent cells among the plurality of cells and each of second storage units connectable to distant cells among the plurality of cells, thereby performing a process of equalizing the energy capacities of the plurality of cells. Effect of the Invention

[0010] As described above, according to the present invention, it is possible to provide an equalization device and an equalization method capable of shortening the time required to equalize the energy capacities of a plurality of cells. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of an equalization device according to a first embodiment. [Diagram 2] FIG. 4 is a diagram for explaining connections between a first capacitor and a second capacitor of the balancing section of the equalizer according to the first embodiment and a cell. [Diagram 3] FIG. 4 is a diagram for explaining the operation (charging of the second capacitor) of the balancing unit of the equalizer according to the first embodiment. [Figure 4] FIG. 4 is a diagram for explaining the operation (charging of a first capacitor) of the balancing unit of the equalizer according to the first embodiment. [Diagram 5] 5 is a flowchart showing an example of a flow of processing performed by a control unit of the equalization device according to the first embodiment. [Figure 6] 4A to 4C are diagrams showing a specific example of cell equalization performed by the equalization device according to the first embodiment. [Figure 7] FIG. 4 is a diagram showing a schematic configuration of an example of an equalization device according to a modified example of the first embodiment. [Figure 8] FIG. 11 is a diagram showing a schematic configuration of an equalization device according to a second embodiment. [Figure 9] FIG. 13 is a diagram showing a schematic configuration of an example of an equalization device according to a modified example of the second embodiment. [Figure 10] FIG. 11 is a diagram for explaining connections between a capacitor C and a capacitor Cs of a balancing section of an equalizer according to a second embodiment and a cell. [Figure 11] 13A and 13B are diagrams for explaining the balancing operation of the equalizer according to the second embodiment. [Figure 12] 10 is a flowchart showing an example of a flow of processes performed in a control unit of an equalization device according to a second embodiment. [Figure 13]11A and 11B are diagrams showing a specific example of cell equalization performed by the equalization device according to the second embodiment. [Figure 14] FIG. 1 is a diagram showing the configuration of an example of a conventional equalization device. [Figure 15] 10A and 10B are diagrams for explaining the operation of an equalization device in a conventional example. [Figure 16] FIG. 13 is a diagram showing the results of equalizing cells in a conventional example when eight cells, cells 1 to 8, are provided, and the remaining cell amounts (%) are 90% for cells 1 and 2, and 60% for the other cells 3 to 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An example of an embodiment of the present invention will be described in detail below with reference to the drawings. In this embodiment, an equalization device that equalizes the energy capacity of each cell of a battery pack in which a plurality of cells are connected in series will be described. Each of the plurality of cells may be a cell that is formed by connecting a plurality of cells in series and integrating them, or a cell that is formed by connecting a plurality of cells in parallel and integrating them. In a battery pack using multiple rechargeable cells such as lithium ion secondary batteries, the states of the multiple cells vary depending on the charging and discharging conditions.

[0013] Due to differences in the state of each cell, particularly differences in energy capacity such as voltage, various problems occur. For example, some cells become overcharged or undercharged during charging. Or, some battery cells become overdischarged during normal use. Or, overdischarging and overcharging further deteriorate the cells, shortening the lifespan of the entire battery pack. Or, if some cells become undercharged, it causes a decrease in the capacity and performance of the entire battery pack.

[0014] Therefore, the equalization device according to the present embodiment performs a process of equalizing the energy capacities of a plurality of cells, thereby suppressing the occurrence of the various problems described above.

[0015] (First embodiment) FIG. 1 is a diagram showing a schematic configuration of an equalization device according to a first embodiment.

[0016] As shown in FIG. 1, the equalization device 10 according to this embodiment includes a BMS (Battery management system) 12 that equalizes imbalances in the energy capacities of the cells 14 in a battery pack composed of a plurality of cells 14.

[0017] The BMS 12 includes a plurality of cells 14, a voltage acquisition unit 16 as an example of a detection unit, a balancing unit 18, and a control unit 20.

[0018] The multiple cells 14 are connected in series, and both ends of each cell 14 are connected to a voltage acquisition unit 16 and a balancing unit 18. Note that the example of Fig. 1 shows an example of a battery pack in which eight cells 14 are connected in series.

[0019] The voltage acquisition unit 16 detects the voltage as an example of the energy capacity of each of the multiple cells 14, thereby acquiring the voltage of each cell 14. The control unit 20 is connected to the voltage acquisition unit 16, and outputs the acquired voltage of each cell 14 to the control unit 20. Note that, in this embodiment, an example of acquiring the voltage of the cell 14 as an example of the energy capacity will be described, but a physical quantity other than the voltage may be acquired as the energy capacity of the cell 14. For example, a charge may be acquired, power may be acquired, or another quantity related to voltage may be acquired.

[0020] The balancing unit 18 is composed of capacitors C1 and C2 that transfer electric charge between the cells 14, and a switch that switches the cell 14 connected to the capacitors C1 and C2. In detail, the balancing unit 18 includes a first capacitor C1 as an example of a first storage unit that can be connected to adjacent cells 14 of the multiple cells 14, and a second capacitor C2 as an example of a second storage unit that can be connected to adjacent cell groups of the multiple cells 14. The balancing unit 18 also includes a switch SW that switches the connection between the capacitor C1 and the cell 14 and the connection between the capacitor C2 and the cell group. The example in FIG. 1 shows an example including two first capacitors C1, one second capacitor C2, and six switches SW.

[0021] The control unit 20 controls the switch SW of the balancing unit 18 based on the voltage of each cell 14 acquired by the voltage acquisition unit 16 to perform a process of equalizing the voltage of each cell. The control unit 20 is configured as a computer, and includes, for example, a microcomputer including a CPU, ROM, and RAM.

[0022] 2 is a diagram for explaining the connection between the first capacitor C1 and the second capacitor C2 of the balancing unit 18 of the equalizer 10 according to this embodiment and the cells 14. In FIG. 2, of the two first capacitors C1, the upper one in FIG. 1 is shown as capacitor X, the lower one in FIG. 1 is shown as capacitor Y, and the second capacitor C2 is shown as capacitor Z. In addition, the cells 14 are shown as cell A, cell B, cell C, and cell D, in order from the upper cell 14 in FIG. 1.

[0023] 2, in the balancing unit 18, the capacitor X can be connected to each of the adjacent cells 14 (cell A and cell B), and the capacitor Y can be connected to each of the adjacent cells 14 (cell C and cell D). The connection between each cell 14 and the capacitors X and Y is switched by a switch SW.

[0024] Capacitor Z can be connected to cell group a including cells A and B, and cell group b including cells C and D. The connection between each cell group and capacitor Z is switched by switch SW.

[0025] Here, the operation of the balancing unit 18 will be described with reference to Figs. 3 and 4. Fig. 3 is a diagram for explaining the operation (charging of the second capacitor C2) of the balancing unit 18 of the equalizer 10 according to this embodiment. Fig. 4 is a diagram for explaining the operation (charging of the first capacitor C1) of the balancing unit 18 of the equalizer 10 according to this embodiment.

[0026] In this embodiment, first, a rough adjustment is performed to equalize the voltages for each of the cell groups a and b, and then a fine adjustment is performed to equalize the voltages for each of the cells 14.

[0027] Specifically, the voltage acquisition unit 16 acquires the voltage from cell A in the upper part of Fig. 3 toward the lower part. Note that the voltage may be acquired from cell D in the lower part of Fig. 3 toward the upper part.

[0028] The control unit 20 compares the voltages starting from the cell group a on the upper side of FIG. 3, and if there is a difference, the balancing unit 18 connects the switch SW of the capacitor Z to the cell group with the larger voltage, and charges the capacitor Z.

[0029] FIG. 3 shows the process of equalizing the cell groups when the cell group a has a higher voltage than the cell group b. That is, in the example of FIG. 3, the cell group a including the cells A and B charges the capacitor Z (second capacitor C2). In this way, the process starts from the capacitor Z in the layer farthest from the cell 14. Note that if there is no difference between adjacent cell groups, the equalization process is skipped. Also, if parallel operation is possible, the equalization processes are performed in parallel.

[0030] Next, when charging is completed, the control unit 20 connects the switch SW to the cell group b including the cells C and D, and charges the cell group b from the capacitor Z. This equalizes the voltages of the cell group a and the cell group b.

[0031] Next, the cells A to D included in each of the cell groups a and b are also equalized by transferring electric charges. That is, for the cells A to D to which the capacitors X and Y (first capacitor C1) are connected, the voltages of the cells 14 are similarly acquired, and the control unit 20 equalizes the voltages. The equalization process is repeated until the voltage difference of each cell 14 falls within a predetermined specified value. Furthermore, when parallel operation is possible, the equalization process is performed in parallel on a plurality of cells 14.

[0032] For example, as shown in the upper part of Figure 4, the switch SW of the capacitor X (first capacitor C1) is connected from the cell A to charge the capacitor X. In parallel with this, the switch SW of the capacitor Y (first capacitor C1) is connected from the cell D to charge the capacitor Y.

[0033] Next, when charging is completed, the control unit 20 switches the connection destination of the switch SW to cells B and C, respectively, as shown in the lower part of Fig. 4, to charge cell B from capacitor X and charge cell C from capacitor Y. This causes the voltages of the cells 14 in each of the cell groups a and b to be equalized. If there is no difference between adjacent cells 14, the equalization process is skipped. Also, if parallel operation is possible, the equalization processes are performed in parallel.

[0034] Next, a specific process performed by the control unit 20 of the equalization device 10 according to the present embodiment configured as described above will be described. Fig. 5 is a flowchart showing an example of the flow of the process performed by the control unit 20 of the equalization device 10 according to the present embodiment. The process of Fig. 5 may be started, for example, when an instruction to equalize the voltages of the cells 14 of the battery pack is given, or when the voltage acquisition unit 16 monitors the voltages of the cells 14 and the voltage difference between the cells 14 becomes equal to or greater than a predetermined threshold. Alternatively, the process may be started at predetermined time intervals.

[0035] In step 100, the control unit 20 acquires the voltage of each cell 14, and the process proceeds to step 102. That is, the control unit 20 acquires the detection result of the voltage of each cell 14 from the voltage acquisition unit 16.

[0036] In step 102, the control unit 20 determines whether the voltage difference between each cell 14 is within a predetermined specified value. If the determination is negative, the process proceeds to step 104, and if the determination is positive, the process ends.

[0037] In step 104, the control unit 20 performs equalization processing for each cell group and proceeds to step 106. The equalization processing for each cell group is performed by the above-mentioned rough adjustment. That is, the cell group is compared with the adjacent cell group from one end side of the battery pack in sequence, and if there is a voltage difference, the switch SW is switched so that the second capacitor C2 is connected to the cell group with the higher voltage, and the second capacitor C2 is charged with an electric charge. When charging is completed, the switch SW is switched to the cell group with the lower voltage, and the cell group with the lower voltage is charged from the second capacitor C2. Then, the same processing is performed for each cell group, thereby equalizing the voltage of each cell group. Note that, if there are many cell groups that can be connected to the second capacitor C2 and parallel operation is possible, the equalization processing is performed in parallel for multiple cell groups.

[0038] In step 106, the control unit 20 performs an equalization process for each cell, and the process proceeds to step 108. The equalization process for each cell is performed by carrying out the fine adjustment described above. That is, for the cell 14 to which the first capacitor C1 is connected, the voltage of each cell 14 is similarly acquired from the voltage acquisition unit 16, and the control unit 20 equalizes the voltage. The equalization process is repeated until the voltage difference of each cell 14 falls within a predetermined specified value. Furthermore, when parallel operation is possible, the equalization process is performed in parallel on multiple cells 14.

[0039] In step 108, the control unit 20 acquires the voltage of each cell 14, and the process proceeds to step 110. That is, the control unit 20 acquires from the voltage acquisition unit 16 the detection result of the voltage after the equalization process.

[0040] In step 110, the control unit 20 judges whether the voltage difference between the cells 14 is within a predetermined value. If the judgment is negative, the process returns to step 104 and the above-mentioned process is repeated. If the judgment is positive, the process ends.

[0041] In this manner, in the equalization device 10 of this embodiment, by performing an equalization process for each cell group and then performing an equalization process for each cell 14, the time required to equalize the voltages of multiple cells can be reduced compared to the case where only an equalization process is performed for each cell 14.

[0042] FIG. 6 is a diagram showing a specific example of equalization of the cells 14 performed by the equalization device 10 according to this embodiment.

[0043] For example, a diagram showing the results of equalization according to this embodiment in a case where eight cells 14, cells 1 to 8, are provided, and the remaining cell amounts (%) are 90% for cells 1 and 2, and 60% for the other cells 3 to 8, is shown.

[0044] 6, the equalizer 10 according to this embodiment performs equalization twice, a first process of equalizing each cell group, and a second process of equalizing each cell 14, thereby equalizing the remaining amount of each cell 14. That is, in this specific example of the equalizer 10 according to this embodiment, the balancing process is required twice until the difference between the average of each cell 14 becomes 0%.

[0045] Here, a conventional equalizer will be described as a comparative example. Fig. 14 is a diagram showing the configuration of an example of a conventional equalizer. Note that the same parts as in this embodiment are denoted by the same reference numerals.

[0046] A case will be described in which, in the equalization device 50 of the conventional example, equalization processing is performed in order from the cells 14 on one end side of the battery pack, and equalization is performed in parallel on the cells 14 that can operate in parallel.

[0047] Like this embodiment, the equalization device 50 of the conventional example also includes a BMS 12, which is configured to include a plurality of cells 14, a voltage acquisition unit 16, a balancing unit 18, and a control unit 20. The voltage acquisition unit 16 acquires the voltage of each cell 14, the control unit 20 determines whether the cells 14 should be equalized, and the balancing unit 18 performs processing to actually equalize the cells 14.

[0048] In the operation of the equalizer 50 of the conventional example, as shown in Fig. 15, voltage is acquired from the cell 14 in the upper side of Fig. 15 to the cell 14 in the lower side, or from the cell 14 in the lower side of Fig. 15 to the cell 14 in the upper side. Fig. 15 is a diagram for explaining the operation of the equalizer of the conventional example.

[0049] That is, the control unit 20 compares the voltages from the upper cells 14, and if there is a difference, the balancing unit 18 connects the switch SW of the capacitor C to the cell 14 with the larger voltage and charges the capacitor C. When charging is complete, the switch SW is switched to the adjacent cell 14, and charging is performed from the capacitor C to the cell 14. The example in Figure 15 shows an example in which the capacitor C is charged from the top cell 14 in Figure 15, and the charge of the capacitor C is transferred to the second cell 14 from the top.

[0050] The same process is performed on the subsequent cells 14, and the process is repeated until all the cells 14 are equalized. If there is no difference between adjacent cells 14, the equalization process is skipped. If parallel operation is possible, the equalization processes are performed in parallel. In the above example, the two cells 14 on the upper side of FIG. 15 and the two cells 14 on the lower side of FIG. 15 can be processed in parallel.

[0051] FIG. 16 is a diagram showing the results of equalizing the cells 14 in a conventional example in a case where eight cells 14, cells 1 to 8, are included and the remaining cell amounts (%) are 90% for cells 1 and 2 and 60% for the other cells 3 to 8.

[0052] When equalization processing is performed as in the conventional example, as shown in Fig. 16, even when the balancing processing is performed seven times, the difference from the average is relatively large, and 318 processes are required to equalize each cell 14. As shown above, in the equalization device 10 according to the present embodiment, it is found that the time required for equalization can be significantly reduced because only two processes are required to equalize each cell 14. Note that Fig. 16 is a diagram showing a part of the processing result when equalization processing is performed in order from the cells at one end of the battery pack to the other end, and the cells 14 that can operate in parallel are equalized in parallel.

[0053] In the present embodiment, a two-stage configuration including a first capacitor C1 that can be connected to adjacent cells of the plurality of cells and a second capacitor C2 that can be connected to some adjacent cell groups of the plurality of cells has been described as an example, but the present invention is not limited to a two-stage configuration. For example, as shown in FIG. 7, a three-stage configuration may be used. That is, a three-stage configuration may be used in which a cell group including more cells 14 than the cells 14 included in the cell group to which the second capacitor C2 can be connected is further included in a third storage unit that can be connected to adjacent cell groups. For example, a configuration may be used in which a third capacitor C3 that can connect two cell groups of the second capacitor C2 as one cell group is provided. Alternatively, a configuration in which the number of capacitor stages is further increased to four or more stages according to an increase in the number of cells may be used.

[0054] Second embodiment Next, an equalizer according to a second embodiment will be described. Fig. 8 is a diagram showing a schematic configuration of an equalizer according to this embodiment. The same parts as those in the above embodiment will be described with the same reference numerals.

[0055] As shown in FIG. 8, the equalization device 11 according to this embodiment includes a BMS (Battery management system) 12 that equalizes the voltage imbalance of each cell 14 in a battery pack composed of a plurality of cells 14.

[0056] The BMS 12 includes a plurality of cells 14, a voltage acquisition unit 16, a balancing unit 18, and a control unit 20.

[0057] The multiple cells 14 are connected in series, and both ends of each cell 14 are connected to a voltage acquisition unit 16 and a balancing unit 18. Note that the example of Fig. 8 shows an example of a battery pack in which eight cells 14 are connected in series.

[0058] The voltage acquisition unit 16 detects the voltage of each of the multiple cells 14 to acquire the voltage of each of the cells 14. The voltage acquisition unit 16 is connected to the control unit 20, and outputs the acquired voltage of each of the cells 14 to the control unit 20.

[0059] The balancing unit 18 is composed of a switch SW for switching the cells 14 and capacitors Cs and C for transferring charges between the cells 14. In detail, the balancing unit 18 includes a capacitor C as an example of a first storage unit that can be connected to adjacent cells 14 among the cells 14, and a capacitor Cs as an example of a second storage unit that can be connected to the cells 14 at both ends as distant cells 14 among the cells 14. The balancing unit 18 also includes a switch SW for switching the connection between the capacitor C and the cells 14, and the capacitor Cs and the cells 14 at both ends. The example of FIG. 8 shows an example including three capacitors C and Cs and four switches SW. In this embodiment, an example is described in which a capacitor Cs is provided that can be connected to the cells 14 at both ends as distant cells 14 among the cells 14, but this is not limited to the cells 14 at both ends, and a capacitor that can be connected to distant cells 14 other than the cells at both ends may be used.

[0060] 9, in the case of four cells 14, the balancing unit 18 may further include a capacitor Cs that can be connected to the cells 14 at both ends in addition to the three capacitors C. FIG. 9 is a diagram showing a modified example of this embodiment.

[0061] The control unit 20 controls the switch SW of the balancing unit 18 based on the voltage of each cell 14 acquired by the voltage acquisition unit 16 to perform a process of equalizing the voltage of each cell. The control unit 20 is configured as a computer, and includes, for example, a microcomputer including a CPU, ROM, and RAM.

[0062] Fig. 10 is a diagram for explaining the connection between the capacitors C and Cs of the balancing unit 18 of the equalizer 11 according to this embodiment and the cells 14. Fig. 10 shows an example in which a capacitor B and a capacitor C are provided as the capacitors C that can be connected to adjacent cells 14 among the multiple cells 14, and a capacitor A is provided as the capacitor Cs that can be connected to the cells 14 at both ends of the multiple cells 14.

[0063] 10, the balancing unit 18 allows each of the capacitors A to C to be connected to an adjacent cell 14. The connections between each cell 14 and the capacitors A to C are switched by a switch SW.

[0064] The capacitor A can be connected to each of the cells 14 at both ends of the battery pack. In the example of Fig. 10, the capacitor A can be connected to the cell A at the top end of Fig. 10 and the cell C at the bottom end of Fig. 10, and the cell 14 connected to the capacitor A is switched by the switch SW.

[0065] Here, the operation of the balancing unit 18 of this embodiment will be described with reference to Fig. 11. Fig. 11 is a diagram for explaining the operation of the balancing unit 18 of the equalizer 11 according to this embodiment.

[0066] The voltage acquisition unit 16 acquires the voltage from the cell A on the upper side of Fig. 11 toward the lower side. Note that the voltage may be acquired from the cell D on the lower side of Fig. 11 toward the upper side.

[0067] The control unit 20 compares the voltages of the cells 14 at both ends, and if there is a difference, the balancing unit 18 connects the capacitor switch SW to the cell 14 with the larger voltage, and charges the capacitor. In the example of Figure 11, capacitor A is charged from cell A.

[0068] Next, when charging is completed, the control unit 20 switches the switch SW to the cell 14 with the smaller voltage, and charges the cell 14 from the capacitor. In the example of Fig. 11, the switch SW is switched to the cell D, and the cell D is charged from the capacitor A.

[0069] Similarly, the voltages of adjacent cells 14 are compared from one end to the other, and if there is a difference, the balancing unit 18 connects the capacitor switch SW to the cell 14 with the larger voltage, and charges the capacitor.

[0070] When charging is completed, the control unit 20 switches the switch SW to the cell 14 with the smaller voltage, and charges the cell 14 from the capacitor.

[0071] The same process is performed on the other cells 14, and the process is repeated until the voltages of all the cells 14 are equalized.

[0072] If there is no difference between adjacent cells 14, the cell balancing process is skipped. Also, if the assigned cell ranges of the capacitors are different, the cell balancing process can be performed in parallel. In the example of Figure 11, the equalization of cells A and B and cells C and D can be performed in parallel.

[0073] In contrast to the conventional example described above, this embodiment is provided with a capacitor that can be connected to each of the cells 14 at both ends. That is, in addition to the method of equalizing the cell voltages of adjacent cells 14, it is also possible to equalize the cell voltages of cells 14 that are far apart from each other.

[0074] Furthermore, in this embodiment, the voltages of the cells 14 at both ends are first equalized, and then the voltages of adjacent cells 14 at both ends of the battery pack are compared and equalized, thereby significantly reducing the time required to equalize the power of multiple cells compared to conventional examples.

[0075] Next, a specific process performed by the control unit 20 of the equalization device 11 according to the present embodiment configured as described above will be described. FIG. 12 is a flowchart showing an example of the flow of the process performed by the control unit 20 of the equalization device 11 according to the present embodiment. The process of FIG. 12 may be started, for example, when an instruction to equalize the voltages of the cells 14 of the battery pack is given, or when the voltage acquisition unit 16 monitors the voltages of the cells 14 and the voltage difference between the cells 14 becomes equal to or greater than a predetermined threshold. Alternatively, the process may be started at predetermined time intervals. The same processes as those in FIG. 5 will be described with the same reference numerals.

[0076] In step 100, the control unit 20 acquires the voltage of each cell 14, and the process proceeds to step 102. That is, the control unit 20 acquires the detection result of the voltage of each cell 14 from the voltage acquisition unit 16.

[0077] In step 102, the control unit 20 determines whether the voltage difference between each cell 14 is within a predetermined specified value. If the determination is negative, the process proceeds to step 105, and if the determination is positive, the process ends.

[0078] In step 105, the control unit 20 performs a process to equalize the cells 14, and then proceeds to step 108. In this embodiment, as described above, the process of equalizing the cells 14 first equalizes the voltages of the cells 14 at both ends, and then compares the voltages of adjacent cells 14 from both ends of the battery pack to equalize the voltages. Note that cells 14 that can be equalized in parallel are processed in parallel.

[0079] In step 108, the control unit 20 acquires the voltage of each cell 14, and the process proceeds to step 110. That is, the control unit 20 acquires from the voltage acquisition unit 16 the detection result of the voltage after the equalization process.

[0080] In step 110, the control unit 20 judges whether the voltage difference between each cell 14 is within a predetermined value. If the judgment is negative, the process returns to step 105 and the above-mentioned process is repeated. If the judgment is positive, the process ends.

[0081] By performing the process in this manner, first the voltages of the cells 14 at both ends are equalized, and then the voltages of adjacent cells 14 from both ends of the battery pack toward the inside are compared and equalized, thereby significantly reducing the time required to equalize multiple cells compared to conventional examples.

[0082] FIG. 13 is a diagram showing a specific example of equalization of the cells 14 performed by the equalizer 11 according to this embodiment.

[0083] For example, a diagram showing the results of equalization according to this embodiment in a case where eight cells 14, cells 1 to 8, are provided, and the remaining cell amounts (%) are 90% for cells 1 and 2, and 60% for the other cells 3 to 8, is shown.

[0084] In the equalization device 11 according to this embodiment, as shown in FIG. 13, the cells 1 and 8 at both ends are equalized, and in parallel, the cells 2 and 3 are equalized. Then, the adjacent cells 14 are equalized from both ends toward the other end. As a result, in this embodiment, in the example of FIG. 13, the capacity of each cell 14 can be equalized by performing equalization 73 times. Therefore, in the equalization device 11 according to this embodiment, the number of balancing processes until the difference from the average becomes 0%, i.e., the time required for equalization, can be significantly reduced compared to the conventional example of FIG. 16 described above.

[0085] In the above embodiment, a capacitor is used as an example of the power storage unit, but the power storage unit is not limited to a capacitor. For example, a series resonant circuit or an inductor may be used.

[0086] Furthermore, the processing performed by the control unit 20 in each of the above embodiments may be software processing performed by executing a program, or may be hardware processing. For example, the processing may be performed by hardware such as a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), and an FPGA (Field-Programmable Gate Array). Alternatively, the processing may be a combination of both software and hardware. In the case of software processing, the program may be stored in various storage media and distributed.

[0087] Furthermore, the present invention is not limited to the above, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention.

[0088] The following supplementary notes are further disclosed regarding the above embodiment.

[0089] (Appendix 1) A first power storage unit connectable to adjacent cells of the plurality of cells connected in series; a second power storage unit connectable to each of adjacent cell groups among the plurality of cells; A detection unit that detects an energy capacity of each of the plurality of cells; a control unit that controls connection of the plurality of cells to each of the first power storage unit and the second power storage unit so as to equalize the energy capacities of the plurality of cells based on a detection result of the detection unit; An equalization device including:

[0090] (Appendix 2) The equalization device described in Appendix 1, wherein the control unit controls the connection of the second storage unit to equalize the energy capacities of the adjacent cell groups, and then controls the connection of the first storage unit to equalize the energy capacities of the adjacent cells.

[0091] (Appendix 3) The equalization device according to claim 1 or 2, further comprising a third power storage unit connectable to each of the adjacent cell groups, the third power storage unit including more cells than the cells included in the cell groups connectable to the second power storage unit.

[0092] (Supplementary Note 4) The equalization device according to Supplementary Note 3, wherein the control unit controls connection of the third power storage unit, the second power storage unit, and the first power storage unit in this order.

[0093] (Appendix 5) a plurality of first power storage units each connectable to adjacent cells among the plurality of cells connected in series; A second power storage unit connectable to each of the plurality of cells at a distance from each other; A detection unit that detects an energy capacity of each of the plurality of cells; a control unit that controls connection of the plurality of cells to each of the first power storage unit and the second power storage unit so as to equalize the energy capacities of the plurality of cells based on a detection result of the detection unit; An equalization device including:

[0094] (Appendix 6) The equalization device described in Appendix 5, wherein the control unit controls the connection of the second storage unit to equalize the energy capacities of the distant cells, and then controls the connection of the first storage unit to equalize the energy capacities of the adjacent cells.

[0095] (Appendix 7) 7. The equalization device according to claim 5, wherein the second power storage unit is connectable to cells at both ends of the plurality of cells.

[0096] (Appendix 8) The computer Detecting the energy capacity of each of the plurality of cells connected in series; An equalization method for controlling connection of the plurality of cells to each of a first storage unit connectable to adjacent cells of the plurality of cells and a second storage unit connectable to a group of adjacent cells of the plurality of cells based on the detection result of the energy capacity, thereby performing a process to equalize the energy capacities of the plurality of cells.

[0097] (Appendix 9) The computer Detecting the energy capacity of each of the plurality of cells connected in series; An equalization method for controlling connection of the multiple cells to each of first storage units that can be connected to adjacent cells among the multiple cells and each of second storage units that can be connected to distant cells among the multiple cells based on the detection results of the energy capacity, thereby equalizing the energy capacities of the multiple cells. [Explanation of symbols]

[0098] 10, 11 Equalizing device 14 Cells 16 Voltage acquisition section 18 Balancing Section 20 Control section C1 First capacitor C2 Second capacitor C3 Third capacitor C, Cs capacitor SW Switch

Claims

1. a first power storage unit connectable to adjacent cells of the plurality of cells connected in series; A second power storage unit connectable to each of adjacent cell groups among the plurality of cells; A detection unit that detects an energy capacity of each of the plurality of cells; a control unit that controls connection of the plurality of cells to each of the first power storage unit and the second power storage unit so as to equalize the energy capacities of the plurality of cells based on a detection result of the detection unit; An equalization device including:

2. 2. The equalization device according to claim 1, wherein the control unit controls the connection of the second storage unit to equalize the energy capacities of the adjacent cell groups, and then controls the connection of the first storage unit to equalize the energy capacities of the adjacent cells.

3. The equalization device according to claim 1 , further comprising a third power storage unit connectable to each of the adjacent cell groups, the third power storage unit including more cells than the cells included in the cell group connectable to the second power storage unit.

4. The equalization device according to claim 3 , wherein the control unit controls the connection of the third power storage unit, the second power storage unit, and the first power storage unit in that order.

5. a plurality of first power storage units each connectable to adjacent cells among the plurality of cells connected in series; A second power storage unit connectable to each of the plurality of cells at a distance from each other; A detection unit that detects an energy capacity of each of the plurality of cells; a control unit that controls connection of the plurality of cells to each of the first power storage unit and the second power storage unit so as to equalize the energy capacities of the plurality of cells based on a detection result of the detection unit; An equalization device including:

6. 6. The equalization device according to claim 5, wherein the control unit controls the connection of the second storage unit to equalize the energy capacities of the distant cells, and then controls the connection of the first storage unit to equalize the energy capacities of the adjacent cells.

7. The equalizer according to claim 5 , wherein the second power storage unit is connectable to each of the cells at both ends of the plurality of cells.

8. The computer Detecting the energy capacity of each of the plurality of cells connected in series; An equalization method for controlling connection of the plurality of cells to each of a first storage unit that can be connected to adjacent cells of the plurality of cells and a second storage unit that can be connected to a group of adjacent cells of the plurality of cells based on the detection result of the energy capacity, thereby performing a process to equalize the energy capacities of the plurality of cells.

9. The computer Detecting the energy capacity of each of the plurality of cells connected in series; An equalization method for controlling connection of the plurality of cells to each of first storage units that can be connected to adjacent cells among the plurality of cells and each of second storage units that can be connected to distant cells among the plurality of cells based on the detection result of the energy capacity, thereby equalizing the energy capacities of the plurality of cells.

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