Power storage device

Abstract

The present invention provides an electric storage device. The electric storage device (10) is configured to connect a plurality of battery cells (12). Each battery cell has: a transformer forming unit (27) which is composed of a first inductor (40), a second inductor (44), a first core component (42), and a second core component (46), and is capable of forming a transformer between adjacent battery cells (12); and a potential detection unit (26) which detects the potential of the battery cell (12). A control unit (80) compares the potentials of adjacent battery cells (12) based on the measurement result of the potential detection unit (26). Furthermore, the control unit (80) supplies charge from a battery cell (12) with a high potential to a battery cell with a low potential, thereby performing equalization control to equalize the potentials of a plurality of battery cells (12). Accordingly, the potentials of a plurality of battery cells can be evenly distributed with a simple structure, and excellent layout properties are achieved.

Description

Technical Field

[0001] The present invention relates to an electric storage device formed by connecting a plurality of battery cells. Background Art

[0002] Japanese Patent Publication No. 2009-540793 discloses a charge equalization device (power storage device) having a plurality of battery cells. Each of the plurality of battery cells has a transformer composed of a primary-side inductor and a secondary-side inductor.

[0003] Specifically, the primary inductor is connected in series with the battery cell and the switch circuit (FET, etc.), and the secondary inductor is connected in parallel with the secondary inductors of other battery cells. The power storage device causes current to flow through the primary inductor of the battery cell with high potential to induce current in the secondary inductor, and causes the current to flow through the secondary inductor of the battery cell with low potential to induce current in the primary inductor. Accordingly, charge is transferred between specified battery cells so that the potentials of the battery cells are relatively close to each other. Summary of the invention

[0004] However, as disclosed in Japanese Patent Publication No. 2009-540793, in a structure where a plurality of battery cells each have a transformer (a primary side transformer, a secondary side transformer) and a switch circuit (FET), the winding deviation of the transformer and the characteristic deviation of the diode of each battery cell become large. Therefore, there is a technical problem that even if charge is transferred from one battery cell to another battery cell, it is difficult to equalize the charge of the plurality of battery cells as a whole with high accuracy.

[0005] Furthermore, if each battery cell includes a transformer composed of a primary-side inductor and a secondary-side inductor, the size of the power storage device increases, which in turn causes a problem in that the layout of the power storage device is degraded.

[0006] The present invention has been made to solve the above-mentioned technical problems, and an object of the present invention is to provide a power storage device that can evenly distribute the potentials of a plurality of battery cells with a simple structure and has excellent layout properties.

[0007] In order to achieve the above-mentioned purpose, according to one embodiment of the present invention, there is provided a power storage device, which is configured to connect a plurality of battery cells, wherein the plurality of battery cells respectively have: a transformer forming unit, which is configured by an inductor and a core component and is capable of forming a transformer between the inductor and the core component of an adjacent battery cell; and a potential detecting unit, which detects the potential of the battery cell. The power storage device also has a control unit, which controls the energization state of the inductors in the plurality of battery cells. The control unit compares the potentials of the adjacent battery cells based on the measurement results of the potential detecting unit, and supplies charge from the battery cell with high potential to the battery cell with low potential via a transformer having the inductor of the battery cell with high potential as the primary side and the inductor of the battery cell with low potential as the secondary side, thereby performing equalization control to equalize the potentials of the plurality of battery cells.

[0008] The above power storage device can evenly distribute the potentials among a plurality of battery cells with a simple structure and has good layout properties.

[0009] The above-mentioned objects, features and advantages will be easily understood through the following description of the embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a perspective view showing the structure of the power storage device according to the first embodiment of the present invention.

[0011] Figure 2 This is a circuit diagram showing a circuit between a plurality of battery cells.

[0012] Figure 3 It is a side cross-sectional view schematically showing the charge transfer structure of a plurality of battery cells.

[0013] Figure 4A It is a perspective view showing the structure of a laminated body forming a transformer. Figure 4B This is a schematic plan view of the first copper wire as viewed from one side in the stacking direction. Figure 4C This is a schematic plan view of the second copper wire as viewed from one side in the stacking direction.

[0014] Figure 5A This is a circuit diagram showing the operation of the first switching circuit in the on phase. Figure 5B This is a circuit diagram showing the operation of the first switching circuit in the off phase.

[0015] Fig. 6A It is an explanatory diagram showing the transfer of electric charge between a plurality of battery cells during equalization control. Figure 6B It is an explanatory diagram showing the state of the potentials of a plurality of battery cells after equalization control.

[0016] Fig. 7A This is a first explanatory diagram showing an example of charge transfer between five battery cells. Figure 7B This is a second explanatory diagram showing an example of charge transfer between five battery cells. Figure 7C This is the third explanatory diagram showing an example of charge transfer between five battery cells. Fig.7D It is a graph showing the potential changes of five battery cells.

[0017] Figure 8 This is a flowchart showing a part of the processing flow of the equalization control.

[0018] Fig. 9 This is a flowchart showing another part of the processing flow of the equalization control.

[0019] Fig.10 This is a flowchart showing another part of the processing flow of the equalization control in another embodiment.

[0020] Fig.11A This is a first explanatory diagram showing an example of charge transfer between battery cells of the power storage device according to the second embodiment. Fig. 11B This is a second explanatory diagram showing an example of charge transfer between battery cells of the power storage device according to the second embodiment.

[0021] Fig.12 is a graph illustrating mapping information for setting a time ratio.

[0022] Fig.13 This is a flowchart showing another part of the processing flow of the equalization control in the power storage device according to the second embodiment.

[0023] Fig.14 This is a flowchart showing the processing flow of the time ratio setting subroutine.

[0024] Fig.15 This is a circuit diagram showing a charge transfer structure and circuit between a plurality of battery cells according to the first modification.

[0025] Fig.16 This is a circuit diagram showing a charge transfer structure and circuit between a plurality of battery cells according to the second variant. DETAILED DESCRIPTION

[0026] Hereinafter, the present invention will be described in detail by listing preferred embodiments and referring to the accompanying drawings.

[0027] [First embodiment]

[0028] like Figure 1As shown, the power storage device 10 involved in the first embodiment of the present invention has a plurality of battery cells 12 as single cells. The plurality of battery cells 12 are connected in series to each other and constitute a stacked body 14 stacked in the direction of arrow A. The stacked body 14 is set on the installation object in a state of being accommodated in a box not shown in the figure, or in a state of being fastened and fixed by a frame member not shown in the figure. The power storage device 10 is applicable, for example, as a vehicle battery for electric vehicles, hybrid vehicles, fuel cell vehicles, etc. In addition, the power storage device 10 can also be applied to a fixed power supply, a power supply for a portable terminal, etc.

[0029] Each battery cell 12 is not particularly limited, and for example, a secondary battery capable of charging and discharging, such as a lithium-ion battery, a nickel-metal hydride battery, a nickel-cadmium battery, a lead-acid battery, a high metal ion battery, and an all-solid battery, can be applied. Each battery cell 12 has: a main body 16 constituting a battery pack; a pair of electrode terminals 18 (+ terminal, - terminal) which serve as power input and output terminals of the main body 16; and a charge transfer structure 20 which is used to monitor the power of each battery cell 12 and transfer charge between each battery cell 12.

[0030] The main body 16 is a rectangular parallelepiped that is wide in the arrow B direction and the arrow C direction and thin in the stacking direction (arrow A direction). Figure 1 The surface on the arrow A2 side is referred to as the first surface 16A, and the surface on the arrow A1 side is referred to as the second surface 16b) and is formed in a substantially flat shape.

[0031] The pair of electrode terminals 18 are connected to electrodes (+ pole and - pole) (not shown) in the main body 16 , and are provided at both ends in the longitudinal direction (arrow B direction) of the upper surface 16 c (end surface on the arrow C1 side) of the main body 16 .

[0032] The charge transfer structure 20 is formed in a plate shape (sheet shape) that is significantly thinner than the thickness of the main body 16, and has a circuit 22 for performing equalization control to equalize the potential of each battery cell 12. The charge transfer structure 20 constitutes a support member, which is arranged in the shape of a Japanese katakana "コ" when viewed from the side, is hooked on the upper surface 16c of the main body 16, and is suspended from the upper surface 16c along the first surface 16a and the second surface 16b of the main body 16. Hereinafter, in the charge transfer structure 20, the portion arranged on the first surface 16a is referred to as the first portion 20a, the portion arranged on the second surface 16b is referred to as the second portion 20b, and the portion arranged on the upper surface 16c is referred to as the third portion 20c.

[0033] like Figure 2As shown, the circuit 22 has a plurality of wirings 24, and has a potential detection unit 26 connected to each wiring 24, a transformer forming unit 27 (a first transformer forming unit 28, a second transformer forming unit 30), a switch circuit 31 (a first switch circuit 32, a second switch circuit 34), and a SW controller 36 (switch controller: Figure 2 abbreviated as SWC) and the communication unit 38.

[0034] The potential detection unit 26 is connected to the electrodes (+ pole, - pole) in the main body 16 via a pair of wirings 24, and detects the potential (cell voltage) of the battery cell 12. In addition, the potential detection unit 26 may also be connected to a pair of electrode terminals 18. The potential detection unit 26 is connected to the communication unit 38 via the wiring 24 for communication, and sends the detected potential information to the communication unit 38.

[0035] The first transformer forming portion 28 is provided at the first portion 20a of the charge transfer structure 20 and is arranged on the first surface 16a of the main body 16. The first transformer forming portion 28 forms a transformer (transformation mechanism) between the second transformer forming portion 30 of the adjacent battery cell 12. In addition, the battery cell 12 arranged at the end portion on the arrow A1 side in the stacked body 14 may also be a structure without the first transformer forming portion 28 and the first switch circuit 32 (i.e., the first portion 20a of the charge transfer structure 20).

[0036] The first transformer forming portion 28 is configured to include a first inductor 40 and a first core member 42 (see Figure 3 ). One end of the first inductor 40 is connected to the electrode (positive pole) in the main body 16 via the wiring 24. The other end of the first inductor 40 is connected to the first switch circuit 32 via the wiring 24. The first core member 42 generates a magnetic flux in a predetermined direction according to the flow direction of the current of the first inductor 40.

[0037] The second transformer forming portion 30 is provided at the second portion 20b of the charge transfer structure 20 and is arranged on the second surface 16b of the main body 16. The second transformer forming portion 30 forms a transformer between the first transformer forming portions 28 of the battery cells 12 adjacent to each other as described above. In addition, the battery cell 12 arranged at the end portion on the arrow A2 side in the stacked body 14 may also be a structure without the second transformer forming portion 30 and the second switch circuit 34 (the second portion 20b of the charge transfer structure 20).

[0038] The second transformer forming portion 30 is configured to include a second inductor 44 and a second core member 46 (see Figure 3). One end of the second inductor 44 is connected to the electrode (+ pole) in the main body 16 via the wiring 24. The other end of the second inductor 44 is connected to the second switch circuit 34 via the wiring 24. The second core member 46 generates a magnetic flux in a predetermined direction according to the flow direction of the current of the second inductor 44. The specific structure of the above-mentioned transformer forming part 27 will be described in detail later.

[0039] The first switch circuit 32 switches between passing and blocking a current from the electrode (+ pole) in the main body 16 via the first inductor 40 toward the electrode (- pole) in the main body 16. In addition, the first switch circuit 32 allows a current to pass from the electrode (- pole) in the main body 16 via the first inductor 40 toward the electrode (+ pole) in the main body 16. The first switch circuit 32 includes a field effect transistor (first FET 48) and a first diode 50.

[0040] The first FET 48 is an element that actually performs switching in the first switch circuit 32. The source of the first FET 48 is connected to the electrode (-pole) in the body 16. The drain of the first FET 48 is connected to the other end of the first inductor 40. The gate of the first FET 48 is connected to the SW controller 36. That is, the first FET 48 switches the passage and cutoff of the current between the source and the drain in the first FET 48 based on the voltage applied to the gate from the SW controller 36.

[0041] The first diode 50 is connected in parallel with the first FET 48 to allow current to pass from the anode to the cathode and to limit current from the cathode to the anode. Specifically, the anode is connected to the wiring 24 between the source and the electrode (-pole) of the first FET 48, and the cathode is connected to the wiring 24 between the drain of the first FET 48 and the first inductor 40.

[0042] The second switch circuit 34 switches between passing and blocking the current flowing from the electrode (+ pole) in the main body 16 via the second inductor 44 to the electrode (- pole) in the main body 16, similarly to the first switch circuit 32. In addition, the second switch circuit 34 allows the current to pass from the electrode (- pole) in the main body 16 via the second inductor 44 to the electrode (+ pole) in the main body 16. The second switch circuit 34 includes a field effect transistor (second FET 52) and a second diode 54.

[0043] The source of the second FET 52 is connected to the electrode (-pole) in the body 16. The drain of the second FET 52 is connected to the other end of the second inductor 44. The gate of the second FET 52 is connected to the SW controller 36. That is, the second FET 52 switches the passage and cutoff of the current between the source and the drain in the second FET 52 based on the voltage applied to the gate from the SW controller 36.

[0044] The second diode 54 is connected in parallel with the second FET 52, allowing current to pass from the anode to the cathode and limiting the passage of current from the cathode to the anode. Specifically, the anode is connected to the wiring 24 between the source and the electrode (-pole) of the second FET 52, and the cathode is connected to the wiring 24 between the drain of the second FET 52 and the second inductor 44.

[0045] The SW controller 36 is connected to the gate of the first FET 48 and the gate of the second FET 52 via the wiring 24. The SW controller 36 is normally in an OFF state in which no voltage is applied to each gate, and applies a voltage to each gate under the command of the control unit 80 of the power storage device 10 described later. That is, under the command of the control unit 80, the SW controller 36 makes the source-drain of the first FET 48 and the source-drain of the second FET 52 in an energized state (ON state).

[0046] The communication unit 38 is connected to the potential detection unit 26 and the SW controller 36 via the communication wiring 24, and is connected to the control unit 80 of the power storage device 10 via the communication line 82, and performs information communication with the control unit 80. The communication unit 38 sends the potential information detected by the potential detection unit 26 to the control unit 80, and when receiving an instruction from the SW controller 36 of the control unit 80, the communication unit 38 outputs the instruction to the SW controller 36.

[0047] Next, refer to Figure 3 , a method of providing the above-mentioned circuit 22 in the charge transfer structure 20 as a supporting member is described. As described above, the charge transfer structure 20 has a first transformer forming portion 28 at a first portion 20a arranged on the first surface 16a of the main body 16, and has a second transformer forming portion 30 at a second portion 20b of the main body 16. In addition, the charge transfer structure 20 is provided with a potential detection portion 26, a first switch circuit 32, a second switch circuit 34, a SW controller 36, and a communication portion 38 (also refer to FIG. 1 ) at a third portion 20c arranged on the upper surface 16c of the main body 16. Figure 2 ).

[0048] The third portion 20c of the charge transfer structure 20 is preferably a rigid-flexible board (hereinafter referred to as substrate 56) on which electrical components can be mounted. The rigid portion 56a of the substrate 56 is composed of a laminated structure in which a base film 58, a copper foil 60, a cover layer 62, a rigid layer 63, etc. are bonded by an adhesive layer (not shown).

[0049] The base film 58 is made of a flexible insulating material such as polyimide resin. The copper foil 60 is a conductive path for electric charges and mainly forms the wiring 24 of the circuit 22. The cover layer 62 is made of an insulating material such as polyimide resin, similarly to the base film 58. In addition, the rigid layer 63 is made of a harder insulating material than the base film 58.

[0050] On the other hand, the flexible portion 56b of the substrate 56 is composed of a laminated structure of a base film 58, a copper foil 60, a cover layer 62, etc. bonded together by an adhesive layer (not shown). The flexible portion 56b is formed with a plurality of fine pores by applying appropriate surface treatment to the cover layer 62, thereby increasing flexibility.

[0051] The substrate 56 thus constructed is easy to mount electrical components, and is easy to three-dimensionally configure by bending the flexible portion 56b. That is, the substrate 56 is constructed so that it extends to the upper end of the first surface 16a and the upper end of the second surface 16b in addition to the upper surface 16c of the main body 16, the rigid portion 56a is located on the upper surface 16c, and the flexible portion 56b is located at the corner of the main body 16 and is bent.

[0052] The copper foil 60 of the rigid part 56a of the substrate 56 is provided on the base film 58 and other layers (for example, the rigid layer 63) via through-holes 64 provided at appropriate positions of each layer. The potential detection unit 26, the first FET 48, the first diode 50, the second FET 52, the second diode 54, the SW controller 36, and the communication unit 38 are mounted on the upper surface of the rigid part 56a. In addition, although Figure 1 , Figure 3 The figure shows a state where an IC chip 65a and a communication connector 65b as a part of the communication unit 38 are arranged on the upper surface of the rigid part 56a, but Figure 2 Of course, appropriate components of the circuit 22 are mounted on the upper surface of the rigid portion 56a. In addition, the third portion 20c is not limited to being applicable to a rigid-flexible board, and a harness of the wiring 24 constituting the circuit 22 and a substrate may be appropriately combined.

[0053] On the other hand, the first portion 20 a includes the first inductor 40 and the first core member 42 of the first transformer forming portion 28 , and also includes a laminated body 66 connected to the substrate 56 and having the first inductor 40 disposed on the first core member 42 .

[0054] The first core component 42 can be applied to a magnetic sheet having a high magnetic permeability by being made of a material such as ferrite. The first core component 42 is configured to extend along the first surface 16a of the main body 16 and to accommodate the stack 66 inside. Specifically, the first core component 42 has: a flat plate portion 42a, which is a square extending in the surface direction of the first surface 16a; a central protrusion 42b, which is provided at the center of the flat plate portion 42a and protrudes toward the arrow A2 side; and an outer protrusion 42c, which is provided outside the flat plate portion 42a and protrudes toward the arrow A2 side and surrounds the outside.

[0055] The laminate 66 is arranged in the arrangement space 43 sandwiched between the central protrusion 42b and the outer protrusion 42c of the first core member 42. The laminate 66 includes a base film 58 continuous with the substrate 56, a copper foil 60 and a cover layer 62, and each layer is bonded by an adhesive layer (not shown).

[0056] In detail, Figure 3 and Figure 4A to Figure 4C As shown in FIG. 1 , a base film 58 is provided at the center of the stacking direction of the stacked body 66. The stacked body 66 is configured by printing copper foil 60 on both sides of the base film 58, and applying an insulating cover layer 62 on the upper layer of the base film 58 and the copper foil 60. The copper foil 60 provided on both sides of the base film 58 respectively constitutes the first inductor 40 in a square spiral shape.

[0057] Therefore, the laminate 66 of the first inductor 40 includes two layers of copper wires (the first copper wire 68 and the second copper wire 70) forming a winding along the surface direction of the first surface 16a. The first copper wire 68 has a spiral portion 68a that spirals counterclockwise from the central portion (central protrusion 42b) toward the outer side in the surface direction, and an extension line 68b that connects the spiral portion 68a to the copper foil 60 of the third portion 20c (the wiring 24 connected to the first switch circuit 32). One end 68ae on the central side of the spiral portion 68a is electrically connected to one end 70ae of the spiral portion 70a of the second copper wire 70 via a through-hole (not shown). The second copper wire 70 has: a spiral portion 70a, which spirals clockwise from the central portion (central protrusion 42b) toward the outside in the surface direction; and an extension line 70b, which is connected from the spiral portion 70a to the copper foil 60 of the third portion 20c (the wiring 24 connected to the electrode (+ pole) in the main body 16).

[0058] Therefore, for example, when current flows from the extension wire 68b, the current flows clockwise from the outer side in the surface direction to the central portion in the first copper wire 68, and the current flows clockwise from the central portion to the outer side in the surface direction in the second copper wire 70, so that the current returns to the extension wire 70b. Accordingly, the spiral portion 68a of the first copper wire 68 and the spiral portion 70a of the second copper wire 70 can form magnetic flux in the same direction (direction perpendicular to the surface direction of the stacked body 66).

[0059] The second portion 20b is the same as the first portion 20a, and includes the second inductor 44 and the second core member 46 of the second transformer forming portion 30, and includes a laminate 72 connected to the flexible portion 56b of the substrate 56 and having the second inductor 44 disposed on the second core member 46. The laminate 72 including the second inductor 44 is formed in a shape symmetrical to the laminate 66 including the first inductor 40 across the body 16, and the second core member 46 is formed in a shape symmetrical to the first core member 42 across the body 16. Therefore, the description of the specific structure of the second inductor 44 (laminate 72) and the second core member 46 is omitted.

[0060] The charge transfer structure 20 is not limited to the structure (support member) provided on the main body 16 by covering the first surface 16a, the second surface 16b, and the upper surface 16c of the main body 16 as described above. For example, the charge transfer structure 20 may be a structure that can be provided on the upper surface 16c of a plurality of main bodies 16 stacked in the stacking direction.

[0061] Refer to Figure 3 In the formed state of the stacked body 14, the first portion 20a of one battery cell 12 (hereinafter referred to as the first cell 12A) and the second portion 20b of another battery cell 12 (hereinafter referred to as the second cell 12B) adjacent to the one battery cell 12 are in surface contact with each other. Therefore, the power storage device 10 can form a transformer between the first cell 12A and the second cell 12B when the first cell 12A causes current to flow through the first portion 20a (or when the second cell 12B causes current to flow through the second portion 20b).

[0062] like Figure 2 As shown, the power storage device 10 transfers the charge of each battery cell 12 by appropriately forming a transformer between adjacent battery cells 12 under the control of the control unit 80. The control unit 80 is composed of a computer having a processor, a memory, and an input / output interface (including a communication function unit) not shown, and is, for example, provided in a box that accommodates each battery cell 12. The control unit 80 communicates with the battery cell 12 via a communication line 82 (see Figure 2 ) is connected to the communication unit 38 of each battery cell 12 in a manner capable of information communication.

[0063] like Figure 5A and Figure 5BAs shown, the control unit 80 appropriately switches the switch circuit 31 on the supply side on and off, thereby transferring the charge between the first unit 12A and the second unit 12B using the transformer. Specifically, the control unit 80 alternately repeats the on phase in which the energy is stored from the battery unit 12 on the supply side to the transformer and the off phase in which the stored energy is transferred from the transformer to the battery unit 12 on the storage side. Next, the operation in the on phase and the off phase when the charge is transferred from the first unit 12A to the second unit 12B will be described.

[0064] In the on phase, the control unit 80 switches the first FET 48 of the first unit 12A from the off state where no voltage is applied to the gate to the on state where voltage is applied to the gate. Here, in the off state, the first FET 48 cuts off the current between the source and the drain, so that no current flows through the first inductor 40. On the other hand, in the on state, the first FET 48 opens between the source and the drain to allow current to flow through the first inductor 40 as the primary side.

[0065] Therefore, by flowing a current in a predetermined direction (helical direction) in the first inductor 40, a potential is generated in the first inductor 40 in a direction that hinders the change of the current. Figure 5A In FIG. 1 , the dotted arrow indicates an upward potential generated in the first inductor 40. With the upward potential of the first inductor 40, an upward potential is also generated in the second inductor 44 on the secondary side.

[0066] However, in the on stage, the control unit 80 continues the off state of the second FET 52 of the second unit 12B in which no voltage is applied to the gate. Therefore, the second FET 52 cuts off the current between the source and the drain, and does not allow the current to flow through the circuit 22 (main body 16, second inductor 44, second FET 52, etc.) on the secondary side. As a result, the potential (energy) generated by the first inductor 40 is accumulated in the first core component 42 of the first unit 12A and the second core component 46 of the second unit 12B forming the transformer.

[0067] Next, in the off phase, the control unit 80 switches the first FET 48 of the first unit 12A from the on state to the off state. Accordingly, the first FET 48 cuts off the current between the source and the drain. When the first FET 48 is turned off, a reverse potential is generated in the transformer to prevent the current from stopping flowing. For example, Figure 5B In FIG. 1 , the potential generated downward by the first inductor 40 is indicated by a dotted arrow.

[0068] Since the first FET 48 on the primary side is in the off state, the energy stored in the first core component 42 and the second core component 46 is released to the circuit 22 on the secondary side. At this time, based on the downward potential of the first inductor 40, a downward potential is generated in the second inductor 44 on the secondary side. The potential of the second inductor 44 is higher than the potential of the main body 16 on the storage side. Therefore, the stored energy flows in the circuit 22 on the secondary side (the electrode (-pole) in the main body 16, the second diode 54, the second inductor 44, and the electrode (+pole) in the main body 16) to charge the main body 16.

[0069] The control unit 80 alternately repeats the above-mentioned on-phase and off-phase at short intervals, thereby moving the charge from the higher side of the cell voltage, that is, the first cell 12A, to the lower side of the cell voltage, that is, the second cell 12B. At this time, the control unit 80 maintains a constant time ratio Duty (= T1 / (T1+T2)) between the implementation period T1 of the on-phase and the implementation period T2 of the off-phase, thereby making the amount of charge movement per unit time the same amount. Accordingly, the potential of the first cell 12A gradually decreases from a state higher than the potential of the second cell 12B, while the potential of the second cell 12B gradually increases, and can become substantially the same after a certain period of time.

[0070] The control unit 80 moves the charge of all the battery cells 12 having the above circuit 22, such as Fig. 6A and Figure 6B As shown, equalization control is performed to equalize the cell voltages of the battery cells 12. For example, the control unit 80 performs equalization control by appropriately judging that the potential variation between the battery cells 12 is small, such as when the vehicle is stopped or when the ignition is off. The start time of the equalization control can be set arbitrarily, and can also be set while the vehicle is running.

[0071] In the equalization control, the control unit 80 detects all the potentials of each battery cell 12 through the potential detection unit 26 of each battery cell 12, and compares the potentials between the adjacent battery cells 12 based on the measurement results. And, between each of the adjacent battery cells 12, the control unit 80 moves the charge from the battery cell 12 with a higher potential to the battery cell 12 with a lower potential.

[0072] Next, refer to FIG. 7A to FIG. 7D , an example of the movement of charge in several (5) battery cells 12 is described. In the following, the five battery cells 12 are simply referred to as cell 1, cell 2, cell 3, cell 4, and cell 5 in order from left (arrow A1 side) to right (arrow A2 side).

[0073] exist Fig. 7AAt the time point t0 shown, when the potential of cell 1> the potential of cell 2> the potential of cell 3, the charge of cell 1 moves toward cell 2, and the charge of cell 2 moves toward cell 3, thereby the charge moves like a bucket relay. In addition, if the potential of cell 4 is higher than the potentials of adjacent cells 3 and 5, the charge of cell 4 is distributed to the left and right sides (cell 3 and cell 5).

[0074] At time point t1 (see Figure 7B ), when the potential of cell 1 > the potential of cell 2, and the potential of cell 2 < the potential of cell 3, the charges of cell 1 and cell 3 move to cell 2. In addition, if the state where the potential of cell 4 is higher than the potentials of cells 3 and 5 continues, the charge of cell 4 continues to be distributed to cells 3 and 5.

[0075] Accordingly, at time point t2 (refer to Figure 7C ), the potential of unit 1, the potential of unit 2 and the potential of unit 3 reach approximately the same potential (potential AV after equalization: Figure 7C Even at this time point t2, when the potential of cell 4 is higher than that of cell 5, the charge of cell 4 moves to cell 5.

[0076] That is, Fig.7D As shown, in the equalization control, the potentials of cells 1 to 5 change so as to gradually converge to the equalized potential AV over time. Then, after time point t3, the potentials of cells 1 to 5 become substantially the same near the equalized potential AV and remain in this state.

[0077] In addition, if Fig. 6A As shown, the control unit 80 stores the limit range V in advance. lim , and for the limited range V lim The control unit 80 performs equalization control on the battery cells 12 with potentials within the limit range V. The limit range refers to the range within which the voltage of each cell does not become overvoltage or overdischarge. On the other hand, the control unit 80 recognizes that the battery cells 12 within the limit range V lim In the case of a battery cell 12 with a potential other than , equalization control is not performed for the battery cell 12. Thus, it is possible to avoid charging the battery cell 12 in an overcharged state or discharging the battery cell 12 in an overdischarged state.

[0078] In addition, if Figure 6B As shown, the control unit 80 stores in advance the allowable potential range V of the potential of each battery cell 12 that is allowed to deviate during the equalization control. accThat is, when the deviation ΔV (potential difference) after subtracting the maximum value from the minimum value of each battery cell 12 is greater than the allowable potential range V acc When the deviation ΔV is within the allowable potential range V acc When the electric potential of each battery cell 12 is within the range of , the control unit 80 stops the movement of charge between the battery cells 12. Accordingly, the control unit 80 can terminate the equalization control in advance at the stage where the electric potential of each battery cell 12 is close to each other to some extent (the electric potential of each battery cell 12 is inconsistent).

[0079] The power storage device 10 according to the present embodiment is basically configured as described above. Figure 8 and Fig. 9 , an example of the processing flow of equalization control is explained.

[0080] The control unit 80 of the power storage device 10 stably monitors the establishment of the start condition of the equalization control, and when it is determined that the start condition is established, the processing flow of the equalization control is implemented. In the equalization control, the control unit 80 first initializes the information acquired or calculated so far (the potential of each battery cell 12, the deviation ΔV (potential difference), etc.) (step S1).

[0081] Next, the control unit 80 receives the measurement results (potential information) measured by the potential detection unit 26 of each battery cell 12 via the communication unit 38 and stores them in the memory (step S2 ). At this time, the control unit 80 obtains all the potentials of the plurality of battery cells 12 .

[0082] The control unit 80 uses the acquired measurement results to extract the maximum value V of the potential from each battery cell 12. cell_max and the minimum potential V cell_min (Step S3). Then, the control unit 80 extracts the maximum value V cell_max Subtract the minimum value V cell_min , to calculate the deviation ΔV (potential difference) of the potential of the entire stack 14 (step S4).

[0083] Steps S1 to S4 are preparatory steps for the equalization control, and thereafter the control unit 80 performs a cell control step for controlling the transfer of charges between adjacent battery cells 12 .

[0084] In the cell control step, the control unit 80 first determines whether the cell control step has been implemented for all of the plurality of battery cells 12 (step S5). If the cell control step has been implemented for all of the battery cells 12, the control unit 80 ends the current equalization control. On the other hand, if there are still battery cells 12 for which the cell control step has not been implemented, the process proceeds to step S6.

[0085] In step S6, the control unit 80 performs an incremental process of moving the target battery cell 12 to an adjacent battery cell 12. For example, the control unit 80 is pre-set to control the circuits 22 of the battery cells 12 in sequence from the battery cell 12 at one end (arrow A1 side) in the stacking direction toward the battery cell 12 at the other end (arrow A2 side) in the stacking direction.

[0086] Then, the control unit 80 sets the potential V of the target battery cell 12 (hereinafter referred to as 12(i) for convenience) to cell(i) The potential V of the battery cell 12 (hereinafter referred to as 12(i-1) for convenience) adjacent to the target battery cell 12(i) cell(i-1) Compare (step S7). In this comparison, V cell(i) >V cell(i-1) In the case of V cell(i) <V cell(i-1) In the case of V cell(i) =V cell(i-1) In this case, the process can end step S7 and return to step S5.

[0087] Steps S8 to S10 are associated with the control of the battery cell 12(i) on the higher potential side and the battery cell 12(i-1) on the lower potential side. In step S8, the control unit 80 determines whether the previously calculated deviation ΔV is within the allowable potential range V. acc The determination of the external potential V of the battery cell 12 (i) cell(i) and the potential V of the battery cell 12(i-1) cell(i-1) Is it within the restricted range V lim In the case of ΔV ≥ V acc And V cell(i) 、V cell(i-1) In the limit range V lim If the value is within the range, the process proceeds to step S9. On the other hand, when ΔV<V acc 、V cell(i) In the limit range V lim In addition, V cell(i-1) In the limit range V lim When any one of the above conditions is met, the process goes to step S10.

[0088] In step S9, the control unit 80 controls the charge of the battery cell 12 (i) to be transferred to the battery cell 12 (i-1). That is, the control unit 80 repeatedly switches the on / off control of the switch circuit 31 of the battery cell 12 (i) that is opposite to the battery cell 12 (i-1) (the above-mentioned on phase and off phase). The control unit 80 repeats the on phase and the off phase for a predetermined period (roughly several μ seconds to several seconds). Accordingly, a certain amount of charge of the battery cell 12 (i) is transferred to the battery cell 12 (i-1) via the transformer.

[0089] On the other hand, in step S10, the control unit 80 does not switch the switch circuit 31 of the battery cell 12 (i) on / off, thereby not implementing the transfer of charge from the battery cell 12 (i) to the battery cell 12 (i-1). Accordingly, unnecessary transfer of charge between the battery cell 12 (i) and the battery cell 12 (i-1) is avoided. Then, after step S9 or step S10 is completed, the control unit 80 returns to step S5 and implements the same processing flow below.

[0090] In addition, steps S11 to S13 are associated with the control of the higher potential side, that is, the battery cell 12(i-1), and the lower potential side, that is, the battery cell 12(i). In step S11, the control unit 80 determines whether the deviation ΔV is within the allowable potential range V in the same manner as step S8. acc In addition, the potential V of the battery cell 12(i) is determined. cell(i) and the potential V of the battery cell 12(i-1) cell(i-1) Is it within the limit range V lim Inside. When ΔV≥V acc And V cell(i) 、V cell(i-1) In the limit range V lim If the value is within the range, the process proceeds to step S12. On the other hand, when ΔV<V acc 、V cell(i) In the limit range V lim In addition, V cell(i-1) In the limit range V lim When any one of the above conditions is met, go to step S13.

[0091] In step S12, the control unit 80 controls the charge of the battery cell 12 (i-1) to be transferred to the battery cell 12 (i). That is, the control unit 80 repeatedly switches the on / off control of the switch circuit 31 of the battery cell 12 (i-1) that is opposite to the battery cell 12 (i) (the above-mentioned on phase and off phase). The control unit 80 repeats the on phase and the off phase for a predetermined period (approximately several μ seconds to several seconds). Accordingly, a certain amount of charge of the battery cell 12 (i-1) is transferred to the battery cell 12 (i) via the transformer.

[0092] On the other hand, in step S13, the control unit 80 does not switch the switch circuit 31 of the battery cell 12 (i-1) on / off, thereby not implementing the transfer of charge from the battery cell 12 (i-1) to the battery cell 12 (i). In addition, after the completion of step S12 or step S13, the control unit 80 returns to step S5 and implements the same processing flow below.

[0093] Through the above processing flow, the control unit 80 moves the charge to all the multiple battery cells 12 as needed. As a result, the potential of each battery cell 12 is equalized. In addition, after the above processing flow is completed, if there is still a potential difference between the battery cells 12, the control unit 80 starts the process again from step S1. The power storage device 10 performs multiple times (for example, Fig.7D The processing flow is performed at each time point t0~t3), and finally the potentials between the battery cells 12 are made roughly the same.

[0094] In addition, the equalization control performed by the power storage device 10 is not limited to the above-mentioned processing flow. For example, the control unit 80 may replace Fig. 9 The processing flow shown is implemented Fig.10 The processing flow shown.

[0095] Specifically, the control unit 80 first determines Figure 8 Whether the deviation ΔV calculated in step S4 is within the allowable potential range V acc Others (ΔV ≥ V acc Then, if the deviation ΔV is within the allowable potential range V acc On the other hand, if the deviation ΔV is within the allowable potential range V acc Within (ΔV<V acc ), it can be said that it is not necessary to implement equalization control of each battery cell 12, so the processing flow is terminated.

[0096] In addition, steps S22 to S24 are performed with Fig. 9 The same processing flow is used for steps S5 to S7. In step S24, when Vcell(i) >V cell(i-1) When V cell(i) <V cell(i-1) When V cell(i) =V cell(i-1) In this case, the process may end step S24 and return to step S21.

[0097] In step S25, the control unit 80 calculates the potential V cell(i) Subtract the potential V of battery cell 12(i-1) cell(i-1) The potential difference DV (refer to Fig. 6A Then, the control unit 80 determines whether the calculated potential difference DV is within the allowable potential range V acc The determination other than that, and the potential V of the battery cell 12(i) cell(i) and the potential V of the battery cell 12(i-1) cell(i-1) Is it within the restricted range V lim Determination within (step S26). acc , and V cell(i) 、V cell(i-1) In the limited range V lim If DV is within V, the process proceeds to step S27. acc 、V cell(i) In the limit range V lim In addition, V cell(i-1) In the limit range V lim When any one of the above conditions is met, the process goes to step S28.

[0098] Step S27 is Fig. 9 The same process as step S9 is performed, thereby transferring the charge of battery cell 12(i) to battery cell 12(i-1). Step S28 is the same as step S9. Fig. 9 The same process as step S10 is performed, thereby avoiding unnecessary movement of charge between the battery cell 12 (i) and the battery cell 12 (i-1).

[0099] In addition, in step S29, the control unit 80 calculates the potential V cell(i-1) Subtract the potential V of the battery cell 12(i) cell(i) Then, the control unit 80 determines whether the calculated potential difference DV is within the allowable potential range V acc The determination other than that, and the potential V of the battery cell 12(i) cell(i) and the potential V of the battery cell 12(i-1) cell(i-1) Is it within the restricted range V limDetermination within (step S30). acc And V cell(i) 、V cell(i-1) In the limited range V lim If DV is less than V, the process proceeds to step S31. acc 、V cell(i) In the limit range V lim In addition, V cell(i-1) In the limit range V lim When any one of the above conditions is met, the process goes to step S32.

[0100] Step S31 is Fig. 9 The same process as step S12 is performed, thereby transferring the charge of battery cell 12(i-1) to battery cell 12(i). Step S32 is the same as step S13. Fig. 9 The same processing as step S13 is performed, thereby avoiding unnecessary movement of charge between the battery cell 12 (i) and the battery cell 12 (i-1).

[0101] As described above, the power storage device 10 may be configured to calculate the potential difference DV between the adjacent battery cells 12(i) and 12(i-1), and compare each potential difference DV with the allowable potential range V acc , when the potential difference DV is within the allowable potential range V acc Thus, the power storage device 10 can transfer charges with high accuracy based on the potential difference DV between the adjacent battery cells 12 .

[0102] As described above, the power storage device 10 according to the first embodiment can transfer charges between a plurality of adjacent battery cells 12 by means of the charge transfer structure 20 provided on the main body 16. Furthermore, the control unit 80 can evenly distribute the potentials of the plurality of battery cells 12 by appropriately controlling the transformer forming unit 27 of the plurality of battery cells 12. In particular, in the power storage device 10, the stacking direction length can be shortened as much as possible by forming the transformer forming unit 27 in a plate shape, wherein the transformer forming unit 27 has the first inductor 40 and the second inductor 44 forming a winding in the surface direction of the main body 16. In addition, the charge transfer structure 20 is configured as a supporting member in the shape of a Japanese katakana "コ" character that can easily arrange the transformer forming unit 27 on the first surface 16a and the second surface 16b of the main body 16, thereby facilitating the installation operation and the like. Furthermore, the control unit 80 maintains the time ratio Duty constant when controlling the on / off of the switch circuit 31 , thereby being able to suppress overshoot and undershoot of the potential of each battery cell 12 .

[0103] [Second embodiment]

[0104] like Fig.11A and Fig. 11B As shown, the power storage device 10A according to the second embodiment is different from the power storage device 10 according to the first embodiment in that the time ratio Duty of the on phase and the off phase of the switch circuit 31 is changed according to the potential difference DV. In addition, the other structures of the power storage device 10A are the same as those of the power storage device 10, and detailed description thereof is omitted.

[0105] That is, the control unit 80 (see Figure 2 ) adjusts the time ratio Duty according to the potential difference DV between the adjacent battery cells 12. Fig.11A and Fig. 11B Take the three battery cells 12 as an example, then Fig.11A In the case of equalization control, before equalization control is performed, the potential of cell 2 is higher than the potential of cell 1 and the potential of cell 3. Therefore, during equalization control, the charge moves from cell 2 to cell 1 and cell 3.

[0106] Here, when comparing the potential of cell 1 and the potential of cell 3, the potential of cell 3 is higher than the potential of cell 1. That is, the potential difference DV1 between cell 1 and cell 2 is greater than the potential difference DV2 between cell 2 and cell 3. In this case, the control section 80 makes the time ratio Duty1 when the charge moves from cell 2 to cell 1 greater than the time ratio Duty2 when the charge moves from cell 2 to cell 3. Accordingly, the charge moving from cell 2 to cell 1 becomes greater than the charge moving from cell 2 to cell 3.

[0107] That is, in the equalization control, the control unit 80 switches the switch circuit 31 on / off at a time ratio Duty corresponding to the potential difference DV between the adjacent battery cells 12. Therefore, the control unit 80 stores (holds) in advance Fig.12 Function or map information 100 showing the relationship between the potential difference DV and the time ratio Duty as shown.

[0108] For example, in the mapping information 100, when the potential difference DV is smaller than the allowable potential range Vacc, the time ratio Duty is zero. low In order to ensure the voltage of the cell voltage to a certain extent, the lower limit time ratio Duty is fixed to low .

[0109] When the potential difference DV is the lower limit value DV low Above the upper limit value DV uppIn the following cases, the time ratio Duty increases linearly with the increase of the potential difference DV. The rising rate (slope) of the time ratio Duty is set to an appropriate constant through experiments, simulations, etc. The control unit 80 multiplies the potential difference DV by a constant to adjust the lower limit value DV. low ~Upper limit value DV upp The time ratio Duty is calculated.

[0110] And, the time ratio Duty is within the upper limit DV upp The upper limit time ratio Duty upp In the mapping information 100, when the potential difference DV becomes larger than the upper limit value DV upp When the time ratio Duty is fixed to the upper limit time ratio Duty upp When calculating the potential difference DV between the adjacent battery cells 12, the control unit 80 reads the above-mentioned function (constant) and the map information 100 of the potential difference DV, and sets the time ratio Duty corresponding to the potential difference DV.

[0111] Next, an example of a processing flow of equalization control will be described for the power storage device 10A according to the second embodiment. In the equalization control, the power storage device 10A performs Figure 8 After the processing flow shown, implement Fig.13 and Fig.14 The processing flow. Fig.13 Steps S41 to S44 are performed with Fig. 9 The same processing is performed as in the processing flow of steps S5 to S8. In step S44, when ΔV ≥ V acc , and V cell(i) 、V cell(i-1) In the limited range V lim If the value is within the range, the process proceeds to step S45. On the other hand, when ΔV<V acc 、V cell(i) In the limit range V lim In addition, V cell(i-1) In the limit range V lim When any one of the above conditions is met, proceed to step S47.

[0112] In step S45, the control unit 80 executes a time ratio setting subroutine. Fig.14 In the time ratio setting subroutine, the control unit 80 uses a function to set the time ratio Duty. In this processing flow, the control unit 80 first calculates the potential difference DV between the battery cell 12 (i) and the battery cell 12 (i-1) adjacent to each other (step S61).

[0113] Next, the control unit 80 calculates the time ratio Duty(i) corresponding to the potential difference DV by multiplying the calculated potential difference DV by a predetermined constant (slope) (step S62). The control unit 80 determines whether the calculated time ratio Duty(i) is greater than the upper limit time ratio Duty(i) held in advance. upp (Step S63) When the time ratio Duty(i) is greater than the upper limit time ratio Duty in step S63 upp , the process proceeds to step S64, in which the control unit 80 sets the upper limit time ratio Duty upp Set as the current time ratio Duty. On the other hand, when the time ratio Duty (i) is the upper limit time ratio Duty upp In the following cases, proceed to step S65.

[0114] In step S65, the control unit 80 determines whether the calculated time ratio Duty(i) is less than the previously stored lower limit time ratio Duty low And, when the time ratio Duty(i) is less than the lower limit time ratio Duty low , the process proceeds to step S66, in which the control unit 80 sets the lower limit time ratio Duty low Set as the current time ratio Duty.

[0115] On the other hand, when the time ratio Duty(i) is the lower limit time ratio Duty low If above, the process proceeds to step S67. In step S67, the control unit 80 sets the calculated time ratio Duty(i) as the current time ratio Duty.

[0116] When the control unit 80 implements any one of steps S64, S66, and S67, it ends the subroutine for setting the time ratio and returns to the main program. Then, in step S46, the control unit 80 controls the charge of the battery cell 12 (i) to be moved to the battery cell 12 (i-1). At this time, the control unit 80 repeatedly turns on / off the switch circuit 31 of the battery cell 12 (i) that faces the battery cell 12 (i-1) according to the time ratio Duty set in step S45. Accordingly, the charge corresponding to the time ratio Duty is moved from the battery cell 12 (i) to the battery cell 12 (i-1).

[0117] On the other hand, when entering step S47 from step S44, the control unit 80 does not perform the charge transfer from the battery cell 12 (i) to the battery cell 12 (i-1). Therefore, the control unit 80 does not implement the subroutine of time ratio setting, and proceeds to step S47. Step S47 is Fig. 9After step S46 or step S47, the control unit 80 returns to step S41 and performs the same processing flow as step S10.

[0118] In addition, when V cell(i) <V cell(i-1) In the case of Fig. 9 The same processing flow as step S11. Then, in step S48, when ΔV ≥ V acc , and V cell(i) 、V cell(i-1) In the limited range V lim If the value is within the range, the process proceeds to step S49. On the other hand, when ΔV<V acc 、V cell(i) In the limit range V lim In addition, V cell(i-1) In the limit range V lim When any one of the above conditions is met, the process goes to step S51.

[0119] In step S49, the control unit 80 performs the same time ratio setting subroutine as step S45 (see Fig.14 ). Based on this, the time ratio Duty for transferring the charge from the battery cell 12(i-1) to the battery cell 12(i) is set.

[0120] After that, the control unit 80 repeatedly turns on / off the switch circuit 31 of the battery cell 12(i-1) that faces the battery cell 12(i) according to the time ratio Duty set in step S49 (step S50). Accordingly, the charge corresponding to the time ratio Duty moves from the battery cell 12(i-1) to the battery cell 12(i).

[0121] On the other hand, when entering step S51 from step S48, the control unit 80 does not perform the transfer of charge from the battery cell 12 (i-1) to the battery cell 12 (i). Therefore, the control unit 80 does not perform the time ratio setting subroutine, and proceeds to step S51. Step S51 is Fig. 9 After step S50 or step S51 is completed, the control unit 80 returns to step S41 and performs the same processing flow as step S13.

[0122] Through the above processing flow, the power storage device 10A moves charges at a time ratio Duty corresponding to the potential difference DV between adjacent battery cells 12. Therefore, the power storage device 10A can complete the movement of charges between the battery cells 12 in a shorter time even when the potential difference DV is large, thereby suppressing power loss and the like.

[0123] In the power storage device 10, 10A, the charge transfer mechanism 20 for transferring the charge of each battery cell 12 can also adopt appropriate modifications according to the spirit of the present invention. Other examples of the communication mechanism between each battery cell 12 and the control unit 80 are described below.

[0124] [First variant]

[0125] Fig.15 The charge transfer structure 20A according to the first modification shown is different from the charge transfer structure 20 described above in that a communication transformer 84 is formed between the communication unit 38 of the adjacent battery cell 12. That is, the plurality of battery cells 12 having the charge transfer structure 20A form a daisy chain, and are configured to communicate between the adjacent battery cells 12 and the control unit 80. Even when the daisy chain is used in this way, the power storage device 10, 10A can transmit and receive necessary information between the adjacent battery cells 12 or the control unit 80.

[0126] [Second variant]

[0127] Fig.16 The charge transfer structure 20B involved in the second variant shown is different from the above-mentioned charge transfer structures 20 and 20A in that a communication line 82 is not provided between the communication unit 38 and the control unit 80, and a wireless communication module 86 is applied to each battery cell 12 and the control unit 80. That is, the multiple battery cells 12 having the charge transfer structure 20B constitute a wireless communication system between each battery cell 12 and between the battery cells 12 and the control unit 80. Even if the wireless communication system is constituted in this way, the power storage device 10, 10A can send and receive necessary information between adjacent battery cells 12 or in the control unit 80. In particular, if the wireless communication module 86 is installed on the substrate 56 in the charge transfer structure 20B, the structure of the battery cell 12 can be further simplified.

[0128] The technical ideas and effects that can be grasped from the above-mentioned embodiments are described below.

[0129] One embodiment of the present invention is a power storage device 10, 10A, which is configured to connect a plurality of battery cells 12, and the plurality of battery cells 12 respectively have: a transformer forming unit 27, which is composed of an inductor (a first inductor 40, a second inductor 44) and a core component (a first core component 42, a second core component 46), and is capable of forming a transformer between the inductor and the core component of the adjacent battery cell 12; and a potential detection unit 26, which detects the potential of the battery cell 12. The power storage device 10, 10A also has a control unit. The control unit 80 controls the energization state of the inductors in the plurality of battery cells 12. The control unit 80 compares the potentials of adjacent battery cells 12 based on the measurement results of the potential detection unit 26, and supplies charge from the battery cell 12 with high potential to the battery cell 12 with low potential via a transformer having the inductor of the battery cell 12 with high potential as the primary side and the inductor of the battery cell 12 with low potential as the secondary side, thereby performing equalization control to equalize the potentials of the plurality of battery cells 12.

[0130] According to the above, the power storage device 10, 10A transfers the charge between the adjacent battery cells 12 during the equalization control, so that the potentials of the plurality of battery cells 12 can be evenly distributed with a simple structure. In addition, the power storage device 10, 10A does not need to provide each battery cell 12 with a transformer composed of a primary side inductor and a secondary side inductor, so that the charge transfer structure 20 for transferring the charge can be miniaturized, and even the structure for performing the equalization control can obtain excellent layout properties.

[0131] The plurality of battery cells 12 have main bodies 16 for charging and discharging electric charge, and transformer forming portions 27 are formed in a plate shape and arranged between adjacent main bodies 16. This facilitates stacking of the battery cells 12 of the power storage device 10, 10A, and enables better layout properties.

[0132] In addition, the plurality of battery cells 12 have transformer forming portions 27 on the side surfaces (first surface 16a, second surface 16b) facing the adjacent battery cells 12, and the inductors (first inductor 40, second inductor 44) are configured with windings along the surface direction of the side surfaces. Thus, even if the power storage device 10, 10A is a structure that uses a transformer to transfer charge, a transformer can be easily formed between adjacent battery cells 12.

[0133] In addition, the core member (first core member 42, second core member 46) is formed in a sheet shape that extends along the side surface (first surface 16a, second surface 16b) and can accommodate the inductor (first inductor 40, second inductor 44) inside, and has a central portion (central protrusion 42b) that contacts the core member of the adjacent battery cell 12 at the center of the inductor, and an outer edge portion (outer edge protrusion 42c) that contacts the core member of the adjacent battery cell 12 on the outside of the inductor. In this way, the power storage device 10, 10A can simply form a transformer between the adjacent battery cells 12 through the sheet-like core member, thereby suppressing the increase in thickness in the stacking direction.

[0134] In addition, each of the plurality of battery cells 12 has a supporting member (charge transfer structure 20) that supports the transformer forming portion 27 and the potential detecting portion 26 and has a conductive path (copper foil 60) for the transformer forming portion 27 and the potential detecting portion 26. In this way, the power storage device 10, 10A supports both the transformer forming portion 27 and the potential detecting portion 26 by means of a supporting member having a conductive path, and thus can be easily installed in each battery cell 12, and the work efficiency can be improved by reducing the number of parts during installation.

[0135] In addition, the support member (charge transfer structure 20) includes: a first portion 20a, which is arranged on one side surface (first surface 16a) of the battery cell 12; a second portion 20b, which is arranged on the side surface (second surface 16b) of the battery cell 12 opposite to the one side surface; and a third portion 20c, which is arranged on the upper surface 16c of the battery cell 12 and connects the first portion 20a and the second portion 20b, the transformer forming portion 27 is provided in the first portion 20a or the second portion 20b, and the potential detection portion 26 is provided in the third portion 20c. According to this, the power storage device 10, 10A can easily arrange the first portion 20a, the second portion 20b, and the third portion 20c at appropriate positions of the battery cell 12 by simply covering the support member from above the main body 16.

[0136] In addition, the switch circuit 31 is provided to turn on / off the inductor (the first inductor 40 and the second inductor 44), and the control unit 80 makes the ratio of the on-time of the inductor energized by the switch circuit 31, that is, the time ratio Duty, constant during the equalization control. Thus, the power storage device 10 can suppress the potential overshoot or undershoot of each battery cell 12 during the equalization control.

[0137] In addition, the switch circuit 31 is provided to turn on / off the inductor (the first inductor 40 and the second inductor 44), and when the control unit 80 performs equalization control, the greater the potential difference DV between adjacent battery cells 12, the greater the time ratio Duty, which is the ratio of the on time of the inductor energized by the switch circuit 31. Thus, the greater the potential difference DV, the greater the time ratio Duty, and thus the power storage device 10A can accelerate the equalization of the potentials between the battery cells 12.

[0138] In addition, the control unit 80 calculates the potential difference DV of the plurality of battery cells 12 based on the measurement result of the potential detection unit 26, and converts the pre-stored allowable potential range V acc Compared with the calculated potential difference DV, when the calculated potential difference DV is greater than the allowable potential range V acc When the calculated potential difference DV is within the allowable potential range V acc In the following cases, the equalization control is not performed. In this way, the power storage devices 10 and 10A can be operated when the potential difference DV between the battery cells 12 is within the allowable potential range V acc By terminating the equalization control at the following time, the execution time of the equalization control can be shortened and the power loss can be suppressed.

[0139] In addition, the control unit 80 stores in advance a limit range V of the potential within which the battery cell 12 does not become overvoltage or overdischarge. lim , and the potential is in the limited range V lim The battery cells 12 in the same battery pack are controlled to be equalized. On the other hand, when the potential is detected to be within the limit range V lim In the case of a battery cell 12 other than , equalization control is not performed for the battery cell 12. Thus, the power storage device 10, 10A can suppress the battery cell 12 from becoming overvoltage or overdischarged, and can perform equalization control well.

[0140] Each of the plurality of battery cells 12 includes a communication unit 38 (wireless communication module 86) for wireless communication with the control unit 80. Thus, the power storage device 10, 10A can reduce the number of communication lines 82, and can simplify the communication system between each battery cell 12 and the control unit 80.

Claims

1. A power storage device (10, 10A) comprising a plurality of battery cells (12) connected together, characterized in that: The plurality of battery cells each comprises: a transformer forming unit (27) which is composed of an inductor (40, 44) and a core member (42, 46) and is capable of forming a transformer between the inductor and the core member of an adjacent battery cell; and a potential detecting unit (26) which detects the potential of the battery cell. The power storage device further includes a control unit (80) that controls the energization state of the inductor in the plurality of battery cells. The control unit compares the potentials of the adjacent battery cells based on the measurement result of the potential detection unit, and supplies charge from the battery cell with high potential to the battery cell with low potential via a transformer having an inductor of the battery cell with high potential as a primary side and an inductor of the battery cell with low potential as a secondary side, thereby performing equalization control to equalize the potentials of the plurality of battery cells. The plurality of battery cells have a main body (16) for charging and discharging the electric charge. The transformer forming part is formed in a plate shape and is arranged between adjacent main bodies. The inductor has a winding formed along the surface direction of the side surfaces (16a, 16b) of the main body. The core member (42, 46) is formed in a sheet shape extending along the side surface and capable of accommodating the inductor inside. The core member has: a central portion (42b) which contacts the core member of the adjacent battery cell at the center of the inductor; and an outer edge portion (42c) which contacts the core member of the adjacent battery cell at the outside of the inductor.

2. The power storage device according to claim 1, characterized in that Each of the plurality of battery cells has a support member (20) that supports the transformer forming portion and the potential detecting portion and has a conductive path (60) between the transformer forming portion and the potential detecting portion.

3. The power storage device according to claim 2, characterized in that The support member comprises: a first portion (20a) arranged on one side surface (16a) of the battery unit; a second portion (20b) arranged on a side surface (16b) of the battery unit opposite to the one side surface; and a third portion (20c) arranged on an upper surface of the battery unit and connected between the first portion and the second portion. The transformer forming portion is provided at the first portion or the second portion, The potential detection unit is provided at the third location.

4. The power storage device according to claim 1, wherein: A switch circuit (31) is provided, the switch circuit (31) turning on and off the energization of the inductor, The control unit makes a time ratio (Duty) constant when performing the equalization control. The time ratio is a ratio of an on-time during which the inductor is energized by the switching circuit.

5. The power storage device according to claim 1, wherein: A switch circuit (31) is provided, the switch circuit (31) turning on and off the energization of the inductor, When performing the equalization control, the control unit increases a time ratio that is a ratio of an on-time during which the inductor is energized by the switch circuit, as a potential difference between the adjacent battery cells increases.

6. The power storage device according to claim 1, characterized in that The control unit calculates the potential difference (DV) of the plurality of battery cells based on the measurement result of the potential detection unit, and converts the pre-stored allowable potential range (V acc ) is compared with the calculated potential difference, When the calculated potential difference is larger than the allowable potential range, the equalization control is performed. On the other hand, when the calculated potential difference is equal to or less than the allowable potential range, the equalization control is not performed.

7. The power storage device according to claim 1, characterized in that The control unit stores in advance a limit range (V lim ), and the equalization control is performed between the battery cells whose potentials are within the limit range. On the other hand, when a battery cell whose potential is outside the limit range is identified, the equalization control of the battery cell is not performed.

8. The power storage device according to claim 1, wherein: Each of the plurality of battery cells has a communication unit (38), and the communication unit (38) performs wireless communication with the control unit.

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