Battery unit charge / discharge control device, charge / discharge control method and charge / discharge control program

Abstract

To prevent overcurrent from flowing to a part of a plurality of batteries or over-charge or over-discharge of the part of the batteries when charging or discharging a battery unit in which the batteries of different capacity or resistance are mixed and connected.SOLUTION: A battery unit charge / discharge control device configured to control charge / discharge of a battery unit in which a plurality of batteries different in resistance or capacity are provided and which is connected to a bus line by battery wiring comprises: a wiring switch which is provided in the battery wiring and switched between an ON state where the battery and the bus line are conducted and an OFF state where the battery and the bus line are shut off; a current acquisition section for acquiring a current value flowing to the batteries; and a battery current control section which switches ON / OFF of the wiring switch based on the current value acquired by the current acquisition section, thereby causing currents corresponding to the resistance or the capacity of the plurality of batteries to flow to the plurality of batteries.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a battery unit charge / discharge control device, a battery unit charge / discharge control method, and a battery unit charge / discharge control program.

Background Art

[0002] Conventionally, there has been a battery unit charge / discharge control device that controls charging or discharging of a battery unit using a battery unit in which a plurality of batteries are connected.

[0003] Examples of this type of battery unit charge / discharge control device include those that connect a plurality of batteries in series to efficiently perform maintenance of each battery (for example, Patent Document 1). Further, examples of this type of battery unit charge / discharge control device include those that connect a plurality of batteries in parallel to efficiently charge and discharge the plurality of batteries (for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, when charging or discharging a plurality of batteries with different capacities or resistances, such as a rechargeable battery, are mixed and connected, and when charging or discharging these plurality of batteries, an overcurrent may flow through some of the batteries, or some of the batteries may be overcharged or overdischarged, posing a risk of failure or fire. Therefore, conventionally, in order to prevent an overcurrent from flowing through some of the batteries or some of the batteries from being overcharged or overdischarged, it is necessary to group the batteries by analyzing the capacity of each battery in advance or measuring the resistance to connect batteries with similar capacities or resistances. Therefore, conventionally, it has been difficult to charge or discharge a plurality of batteries while suppressing an overcurrent from flowing through some of the batteries or some of the batteries from being overcharged or overdischarged in a state where a plurality of batteries with different capacities or resistances are mixed and connected.

[0006] Therefore, the present invention has been made in view of the above-described problems, and when charging or discharging a battery unit in which a plurality of batteries with different capacities or resistances are mixed and connected, its main object is to prevent an overcurrent from flowing through some of the batteries or some of the batteries from being overcharged or overdischarged.

Means for Solving the Problems

[0007] That is, a battery unit charge / discharge control device according to the present invention is a battery unit charge / discharge control device that controls charging or discharging of a battery unit connected to a bus by a battery wiring provided with a plurality of batteries having different resistances or capacities, the battery wiring being provided with a wiring switch that switches between an on state in which the battery and the bus are electrically connected and an off state in which the battery and the bus are disconnected, a current acquisition unit that acquires a current value flowing through the battery, and a battery current control unit that causes a current corresponding to the resistance or capacity of the plurality of batteries to flow through the plurality of batteries by switching the on / off of the wiring switch based on the current value acquired by the current acquisition unit.

[0008] With such a battery unit charge / discharge control device, the battery current control unit switches the on / off state of the wiring switch based on the current value flowing through the battery, so that a current corresponding to the resistance or capacitance of each battery flows through each battery, thereby preventing some batteries from being overcharged or an overcurrent from flowing. Therefore, it is possible to charge or discharge these multiple batteries while suppressing an overcurrent from flowing through some batteries or some batteries from being overcharged or overdischarged in a state where multiple batteries with different capacitances or resistances are mixed and connected. In addition, since it is not necessary to group batteries such as connecting batteries with similar capacitances or resistances, it is possible to eliminate complicated and time-consuming analyses such as battery history analysis or battery degradation analysis. As a result, the man-hours required for the design or construction of the battery unit can be reduced. In addition, since it is not necessary to group the batteries, it is not necessary to select multiple batteries with different capacitances or resistances, such as reusable batteries that make up the battery unit, from within the same group. As a result, the degree of freedom in selecting the batteries that make up the battery unit when designing or constructing the battery unit can be increased compared to the prior art.

[0009] As a specific embodiment for flowing a current corresponding to the resistance or capacitance through a plurality of batteries, it further includes a reactor interposed between the wiring switch and the battery, and a diode connected in parallel with the battery. In the off state, current flows through the diode via the reactor, and in the on state, current flows between the busbars via the wiring.

[0010] With such a configuration, when the wiring switch is switched from the on state to the off state, the current flowing between the bus and the battery is interrupted, while the current flowing through the diode can be gradually decreased via the reactor. Further, when the wiring switch is switched from the off state to the on state, current flows between the bus and the battery, and the current flowing between the buses can be gradually increased by the reactor. As a result, a sudden change in current when the wiring switch is switched between the on state and the off state can be suppressed, so that a failure of the battery or the wiring switch due to the current change can be prevented.

[0011] As a specific aspect for more surely flowing a current corresponding to the resistance or capacitance of the battery to the battery, the battery current control unit turns off the wiring switch when the current value is greater than a predetermined first threshold value, and turns on the wiring switch when the current value is less than a second threshold value which is a threshold value smaller than the first threshold value.

[0012] With such a configuration, since the current flowing through the battery is controlled based on the first threshold value and the second threshold value having different magnitudes, the current flowing through the battery can be controlled near a set value set between the first threshold value and the second threshold value. As a result, by setting the set value to an appropriate value, it is possible to more surely prevent an overcurrent from flowing through the battery or the battery from being overcharged or overdischarged.

[0013] Here, for example, in a battery unit in which a plurality of batteries are connected in series, if the capacities of the respective batteries are different, the battery having a smaller capacity is fully charged or completely discharged earlier than the battery having a larger capacity, so there is a risk that the battery having a smaller capacity may be overcharged or overdischarged. Conventionally, in order to prevent overcharging of the battery, it is necessary to analyze the capacity of each battery in advance and connect batteries having similar capacities in series. Therefore, it is preferable that the battery unit to be controlled by the battery unit charge / discharge control device has a plurality of the batteries connected in series to the bus.

[0014] With such a configuration, the battery current control unit switches the on / off state of the wiring switch based on the current value, so that a current corresponding to the capacity of each battery flows through the plurality of batteries. Therefore, overcharging of the batteries caused by differences in the capacities of the respective batteries can be prevented. Particularly in the case of reuse batteries, since the types of batteries or the states of deterioration of the batteries are different, the capacities of the respective batteries often differ. Therefore, conventionally, in order to prevent overcharging of the batteries, it is necessary to connect batteries of the same type or batteries with similar states of deterioration in series. On the other hand, according to the present invention, since the battery current control unit causes a current corresponding to the capacity of each battery to flow through each battery, batteries with different capacities can be mixed and connected in series.

[0015] It is further provided with a shunt circuit having one end connected to the wiring between the wiring switch and the battery and the other end connected between the battery and the bus bar. It is desirable that current flows between the bus bars through the wiring in the on state and current flows between the bus bars through the shunt circuit in the off state.

[0016] With such a configuration, in the off state of the wiring switch, current flows between the bus bars through the shunt circuit. Therefore, even when the wiring switch is in the off state, one or a plurality of batteries connected in series with the battery continue to be charged or discharged. As a result, charging or discharging of the plurality of batteries constituting the battery unit can be completed almost simultaneously.

[0017] As a specific embodiment of the shunt circuit, it includes a shunt switch that makes and breaks the electrical connection and disconnection between the battery wiring and the shunt circuit, a shunt reactor connected to the shunt switch, and a shunt diode provided in parallel with the shunt reactor. When the wiring switch switches from the off state to the on state, the shunt switch is opened and current flows from the shunt reactor to the shunt diode.

[0018] With such a configuration, when the wiring switch changes from the off state to the on state and the shunt circuit is electrically disconnected from the bus, current flows between the shunt reactor and the shunt diode in the shunt circuit. As a result, when the wiring switch is turned off again and the shunt circuit is electrically connected to the bus, a large current from the bus can be prevented from flowing suddenly into the shunt circuit, protecting the shunt switch.

[0019] Preferably, a capacitor is further provided between the bus and the wiring switch and is connected in parallel with the shunt circuit.

[0020] With such a configuration, since charge is accumulated in the capacitor by the current flowing from the bus, when the wiring switch is switched from the on state to the off state and the battery is disconnected, the capacitor can hold a voltage corresponding to the electromotive force of the battery.

[0021] Here, for example, in a battery unit in which a plurality of batteries are connected in parallel, if the resistances of the respective batteries are different, a larger current will flow through the battery with a smaller resistance than through the battery with a larger resistance, so there is a risk of overcurrent flowing through the battery with a smaller resistance. Conventionally, in order to prevent overcurrent from flowing through the battery, it is necessary to measure the resistance of each battery in advance and connect batteries with similar resistances in parallel. Therefore, in the battery unit charge and discharge control device, it is preferable that a plurality of the batteries are connected in parallel to the bus.

[0022] With such a configuration, by switching the on / off state of the wiring switch based on the current value by the battery current control unit, currents corresponding to the resistances of the plurality of batteries are made to flow through the plurality of batteries, so overcurrent caused by differences in the resistances of the respective batteries can be prevented. Particularly in the case of a rechargeable battery, since the degradation states of the batteries are different, the resistances of the respective batteries often differ. Therefore, conventionally, in order to prevent an overcurrent from flowing through the battery, it has been necessary to connect batteries with similar degradation states in parallel, making it difficult to expand the capacity of the battery unit. On the other hand, according to the present invention, since the battery current control unit causes a current corresponding to the resistance of each battery to flow through each battery, batteries with different degradation states can be mixed and connected in parallel, and the capacity of the battery unit can be easily expanded.

[0023] A charge / discharge control method using a battery unit charge / discharge control device that controls the charge or discharge of a battery unit connected to a bus by a battery wiring provided with a plurality of batteries having different resistances or capacitances, wherein the battery unit charge / discharge control device is provided in the battery wiring and includes a wiring switch that switches between an on state in which the battery and the bus are electrically connected and an off state in which the battery and the bus are disconnected, and the charge / discharge control method is characterized by obtaining a current value flowing through the battery and switching the on / off of the wiring switch based on the obtained current value, thereby causing a current corresponding to the resistance or capacitance of the plurality of batteries to flow through the plurality of batteries. A charge / discharge control program used in a battery unit charge / discharge control device that controls the charge or discharge of a battery unit connected to a bus by a battery wiring provided with a plurality of batteries having different resistances or capacitances, wherein the battery unit charge / discharge control device is provided in the battery wiring and includes a wiring switch that switches between an on state in which the battery and the bus are electrically connected and an off state in which the battery and the bus are disconnected, and the charge / discharge control program causes a computer to function as a current acquisition unit that acquires a current value flowing through the battery and a battery current control unit that causes a current corresponding to the resistance or capacitance of the plurality of batteries to flow through the plurality of batteries by switching the on / off of the wiring switch based on the current value acquired by the current acquisition unit.

[0024] With such a configuration, the same operational effects as those of the battery unit charge / discharge control device described above can be obtained.

Effects of the Invention

[0025] According to the present invention configured as described above, when charging or discharging a battery unit in which a plurality of batteries having different capacities or resistances are mixed and connected, it is possible to prevent an overcurrent from flowing through some of the batteries, or some of the batteries from being overcharged or overdischarged.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiment for Carrying Out the Invention

[0027] <First Embodiment of the Present Invention> Hereinafter, an embodiment of a battery unit control device according to the present invention will be described with reference to the drawings. Note that, for the sake of clarity, any of the figures shown below may be schematically drawn with appropriate omissions or exaggerations. The same reference numerals are assigned to the same components, and the description thereof will be omitted as appropriate.

[0028] <Overall Configuration of Battery Unit Charge / Discharge Control Device> The battery unit charge / discharge control device 100 in the present embodiment controls the charging or discharging of a battery unit composed of a plurality of batteries B having different resistances or capacitances.

[0029] Here, the plurality of batteries constituting the battery unit are provided on the battery wiring L and are electrically connected to the bus bar G via the battery wiring L. In the present embodiment, the bus bar G is connected to a power source or a load (not shown) and a current corresponding to the power source or the load flows therethrough. Specifically, the bus bar G has a positive electrode side bus bar G1 which is the bus bar to which the positive electrode side of the battery unit is connected and a negative electrode side bus bar G2 which is the bus bar to which the negative electrode side of the battery unit is connected. One end of the battery wiring L is connected to the positive electrode side bus bar G1, and the other end of the battery wiring L is connected to the negative electrode side bus bar G2.

[0030] The battery B in this embodiment is a reuse battery, for example, a battery that reuses a battery mounted on an electric vehicle or a hybrid vehicle. Note that the type of the battery B is a secondary battery, a lead storage battery, or other rechargeable batteries. In this embodiment, the number of the batteries B is two. The battery connected to the positive electrode side bus bar G1 is defined as the battery B1, and the battery connected to the battery B1 is defined as the battery B2. Note that although the number of the batteries B is two in this embodiment, it may be three or more.

[0031] Specifically, as shown in FIG. 1, the battery unit charge / discharge control device 100 includes a wiring switch 10 provided in the battery wiring L, a diode 20 connected in parallel to the battery B1, a reactor 30 interposed between the wiring switch 10 and the battery B1, a shunt circuit 40 having one end branched and connected to the battery wiring L on the positive electrode side bus bar G1 side of the wiring switch 10 and the other end connected to the battery wiring L on the negative electrode side bus bar G2 side of the battery B1, a capacitor 50 connected in parallel to the shunt circuit 40, and a control mechanism 60 that controls various devices. Hereinafter, each part will be described.

[0032] The wiring switch 10 can be switched between an on state in which the battery B1 and the bus bar G are electrically connected and an off state in which the battery B1 and the bus bar G are disconnected. In this embodiment, the wiring switch 10 is provided in the battery wiring L on the positive electrode side bus bar G1 side of the battery B1. Note that the on / off switching of the wiring switch 10 is performed by the control mechanism 60 described later.

[0033] The diode 20 allows current to flow when the wiring switch 10 is in the off state. In this embodiment, when the wiring switch 10 switches from the on state to the off state, current flows through the diode 20, causing the current to flow back to the battery B1. On the other hand, when the wiring switch 10 switches from the off state to the on state, no current flows through the diode 20, and current flows between the bus bars G through the battery wiring L.

[0034] In this embodiment, the diode 20 is composed of two diodes, namely a first diode 21 and a second diode 22. The first diode 21 allows current to flow in the direction in which current flows through the battery B1 when the wiring switch 10 is in the off state during charging of the battery unit. The second diode 22 allows current to flow in the direction in which current flows through the battery B1 when the wiring switch 10 is in the off state during discharging of the battery unit. Note that the number of diodes 20 is not limited to two.

[0035] Here, the diode 20 is provided with a diode switch SW for switching the conduction and opening of the current flowing through the diode 20 according to the charging of the battery unit or the discharging of the battery unit. Specifically, the diode switch SW includes a first diode switch SW1 provided corresponding to the first diode 21 and a second diode switch SW2 provided corresponding to the second diode 22. When the battery B1 is being charged, the first diode switch SW1 is conducting and the second diode switch SW2 is open. On the other hand, when the battery B1 is discharging, the first diode switch SW1 is open and the second diode switch SW2 is conducting.

[0036] The reactor 30 prevents a sudden current from flowing through the battery B1 when switching the on / off state of the wiring switch 10. That is, an induced current flows through the reactor 30 to prevent the change in magnetic flux generated by the switching between the on state and the off state of the wiring switch 10, thereby suppressing the current fluctuation when switching the on state and the off state of the wiring switch 10.

[0037] The shunt circuit 40 allows current to flow from the busbar G when the wiring switch 10 is in the off state and prevents current from flowing from the busbar G when the wiring switch 10 is in the on state. Specifically, the shunt circuit 40 includes a shunt switch 41 that electrically connects and disconnects the battery wiring L and the shunt circuit 40, a shunt reactor 42 connected to the shunt switch 41, a shunt diode 43 provided in parallel with the shunt reactor 42, and a shunt diode switch 44 provided on the negative electrode side busbar G2 side of the shunt diode 43.

[0038] The shunt switch 41 electrically connects the battery wiring L and the shunt circuit 40 when the wiring switch 10 is in the off state and electrically disconnects the shunt circuit 40 from the battery wiring L when the wiring switch 10 is in the on state. The electrical connection and disconnection of the shunt switch 41 are performed by a control mechanism 60 described later.

[0039] The shunt reactor 42 suppresses sudden current fluctuations that occur when the connection and disconnection of the shunt switch 41 are switched. That is, an induced current flows through the shunt reactor 42 to prevent changes in magnetic flux caused by the switching between the on state and the off state of the wiring switch 10, suppressing sudden current fluctuations when the connection and disconnection of the shunt switch 41 are switched.

[0040] The shunt diode 43 returns current to the shunt reactor 42 when the shunt switch 41 is open. In this embodiment, the shunt diode 43 is composed of two diodes, a first shunt diode 43a and a second shunt diode 43b. Note that the shunt diode 43 is not limited to two.

[0041] The first shunt diode 43a allows current to flow in the direction in which current flows through the shunt reactor 42 when the battery B1 is being charged and the shunt switch 41 is open. The second shunt diode 43b allows current to flow in the direction in which current flows through the shunt reactor 42 when the battery B1 is discharging and the shunt switch 41 is open.

[0042] The shunt diode switch 44 includes a first shunt diode switch 44a provided corresponding to the first shunt diode 43a and a second shunt diode switch 44b provided corresponding to the second shunt diode 43b. When the battery B1 is being charged, the first shunt diode switch 44a is conducting and the second shunt diode switch 44b is open. On the other hand, when the battery B1 is discharging, the first shunt diode switch 44a is open and the second shunt diode switch 44b is conducting.

[0043] The capacitor 50 is provided between the bus bar G and the wiring switch 10 and is connected in parallel with the shunt circuit 40. When the shunt switch 41 is open, current flows from the bus bar G to the capacitor 50 and charges are accumulated.

[0044] The control mechanism 60 is a so-called computer including a CPU, a memory, an A / D converter, an input / output interface, etc. Based on a program stored in the memory, these components cooperate with each other to function as a current acquisition unit 61, a battery current control unit 62, etc., as shown in FIG. 1.

[0045] The current acquisition unit 61 acquires the current value flowing through at least one of the plurality of batteries B constituting the battery unit. In the present embodiment, the current acquisition unit 61 acquires the current value flowing through the battery B1. Here, the current acquisition unit 61 acquires the current value via a current transformer (not shown) provided on the battery wiring L where the battery B1 is provided.

[0046] The battery current control unit 62 switches the on / off state of the wiring switch 10 based on the current value acquired by the current acquisition unit 61, so as to cause a current corresponding to the resistance or capacitance of the plurality of batteries B to flow through the plurality of batteries B.

[0047] Specifically, the battery current control unit 62 includes a feedback control unit 621 that controls the acquired current value so as to be the target value of the current flowing through the battery B1, a PWM signal generation unit 622 that outputs an on signal for turning on the wiring switch 10 or an off signal for turning off the wiring switch 10, and a shunt switch control unit 623 that controls conduction or opening of the shunt switch 41 in response to the output of the on signal or the off signal.

[0048] The feedback control unit 621 controls the current value acquired by the current acquisition unit 61 so as to be the target value. In the present embodiment, the target value of the current flowing through the battery B1 is calculated by the following formula (1).

[0049]

Formula

[0050] Here, I set is the target value of the current flowing through the battery B1, Q is the capacity of the battery B1, SOC is the charge rate of the battery B1, and C is the time rate (C rate) of the battery B1. Note that the target value of the current flowing through the battery B1 is set to be equal to or less than the current flowing through the battery wiring L.

[0051] Here, the feedback control unit 621 controls the current flowing through the battery B1 to the target value by comparing the current value flowing through the battery B1 with a threshold value. Specifically, the feedback control unit 621 has two threshold values, a first threshold value and a second threshold value, and the second threshold value is a value smaller than the first threshold value. Also, the target value of the current flowing through the battery B1 is set to a value larger than the second threshold value and smaller than the first threshold value.

[0052] More specifically, the feedback control unit 621 determines whether the current value flowing through the battery B1 is equal to or greater than the first threshold value. And when the current value flowing through the battery B1 is equal to or greater than the first threshold value, the feedback control unit 621 commands the PWM signal generation unit 622 to output an on signal.

[0053] In addition, the feedback control unit 621 determines whether the current value flowing through the battery B1 is equal to or less than the second threshold value. When the current value flowing through the battery B1 is equal to or less than the second threshold value, the feedback control unit 621 instructs the PWM signal generation unit 622 to output an off signal.

[0054] The PWM signal generation unit 622 outputs an on signal or an off signal based on the instruction of the feedback control unit 621. In the present embodiment, the PWM signal generation unit 622 switches between the on signal and the off signal by PWM control. Specifically, when the feedback control unit 621 instructs to output an on signal, the PWM signal generation unit 622 outputs an on signal. On the other hand, when the feedback control unit 621 instructs to output an off signal, the PWM signal generation unit 622 outputs an off signal.

[0055] The shunt switch control unit 623 is a so-called logic inverter that receives the output of the on signal or the off signal and inverts the output. Specifically, when the PWM signal generation unit 622 outputs an on signal, the shunt switch control unit 623 outputs an open signal for opening the shunt switch 41. When the PWM signal generation unit 622 outputs an off signal, the shunt switch control unit 623 outputs a conduction signal for conducting the shunt switch 41.

[0056] <Charge control method> Next, a battery unit charge control method using the battery unit charge / discharge control device 100 in the first embodiment will be described with reference to FIGS. 2 to 5. Here, the batteries B1 and B2 constituting the battery unit are connected in series. Also, the maximum capacity of the battery B1 is assumed to be smaller than the maximum capacity of the battery B2, and target values corresponding to the initial SOC (State Of Charge) of each battery are set for each battery according to the maximum capacity of each battery. Note that the direction of the arrow in FIGS. 2 to 5 indicates the direction in which the current flows.

[0057] As shown in Fig. 2(a), a battery unit composed of batteries B1 and B2 is connected in series to the bus bar G by a battery wiring L. Then, by turning on the wiring switch 10, current is supplied from the bus bar G to the battery unit, and charging of the battery unit is started. In Fig. 2(a), the first diode switch SW1 and the first shunt diode switch 44a are conducting, and the shunt switch 41, the second diode switch SW2, and the second shunt diode switch 44b are open. In Fig. 2(a), current is supplied to the capacitor 50 from the bus bar G, and charge is accumulated in the capacitor 50.

[0058] Also, in Fig. 2(a), the current acquisition unit 61 acquires the current value flowing through the battery B1, and the feedback control unit 621 compares the acquired current value with the target value. In Fig. 2(b), current having a value equal to or greater than the first threshold value flows through the battery B1.

[0059] When the current value flowing through the battery B1 becomes equal to or greater than the first threshold value, as shown in Fig. 3(a), in response to a command from the feedback control unit 621, the PWM signal generation unit 622 outputs an off signal, and the wiring switch 10 becomes off.

[0060] As a result, current from the bus bar G no longer flows through the battery B1. Also, since the first diode switch SW1 is conducting, current flows through the battery B1 via the first diode 21. Then, due to the reactor 30, the current flowing through the battery B1 via the first diode 21 gradually decreases, so as shown in Fig. 3(b), the current flowing through the battery B1 gradually decreases with the passage of time.

[0061] Also, as shown in FIG. 3(a), upon receiving the off signal output by the PWM signal generation unit 622, the shunt switch control unit 623 outputs a conduction signal, and the shunt switch 41 is introduced. As a result, as shown in FIG. 3(a), the current supplied from the bus G flows through the shunt reactor 42 provided in the shunt circuit 40 and then flows to the battery B2 provided in the battery wiring L on the lower voltage side than the battery B1.

[0062] When the current value flowing through the battery B1 becomes a value equal to or less than the second threshold value, as shown in FIG. 4(a), in response to a command from the feedback control unit 621, the PWM signal generation unit 622 outputs an on signal, and the wiring switch 10 becomes in an on state. Also, upon receiving the on signal output by the PWM signal generation unit 622, the shunt switch control unit 623 outputs an open signal, and the shunt switch 41 is opened.

[0063] As a result, as shown in FIG. 4(a), the current supplied from the bus G flows through the battery B1 and the battery B2. Consequently, as shown in FIG. 4(b), the current flowing through the battery B1 increases with the passage of time. Also, in the shunt circuit 40, current is flowing between the shunt reactor 42 and the first shunt diode 43a.

[0064] Then, when the current value flowing through the battery B1 becomes a value equal to or greater than the first threshold value, as shown in FIG. 5(a), in response to a command from the feedback control unit 621, the PWM signal generation unit 622 outputs an off signal, and the wiring switch 10 becomes in an off state. Also, upon receiving the off signal output by the PWM signal generation unit 622, the shunt switch control unit 623 outputs a conduction signal, and the shunt switch 41 is made conductive.

[0065] As a result, in FIG. 5(a) as well as in FIG. 3(a), the current from the bus bar G is no longer supplied to the battery B1. Also, since the first diode switch SW1 is conducting, a current flows through the first diode 21 to the battery B1. Then, due to the reactor 30, the current flowing through the first diode 21 to the battery B1 gradually decreases. Therefore, as shown in FIG. 5(b), the current flowing through the battery B1 gradually decreases with the passage of time.

[0066] Until the charging of the battery units B1 and B2 is completed, the battery unit charge / discharge control device 100 compares the magnitude relationship between the current value and the first threshold value or the second threshold value in the same manner as the methods shown in FIGS. 3 to 5, and controls the opening and closing of the wiring switch 10 and the shunt switch 41.

[0067] As a result, in the steady state, the current supplied from the bus bar G to the battery unit appears to flow to each of the batteries B1 and B2 according to the maximum capacity of each battery B1 and B2. Specifically, it appears that a current corresponding to the maximum capacity of the battery B1 flows through the battery wiring L provided with the battery B1, and a current corresponding to the maximum capacity of the battery B2 flows through the shunt circuit 40.

[0068] <Discharge control method> Next, a discharge control method for the battery unit using the battery unit charge / discharge control device 100 in the first embodiment will be described.

[0069] A battery unit composed of the batteries B1 and B2 is connected in series to the bus bar G by the battery wiring L. Then, by turning on the wiring switch 10, a current flows from the battery unit to the bus bar G, and the discharge of the battery unit is started. When the battery unit is discharged, since a current flows from the battery unit to the bus bar G, the direction of the current during the discharge of the battery unit is reversed compared to when the battery unit is charged.

[0070] When the wiring switch 10 switches from the on state to the off state, the second diode switch SW2 conducts, and current flows from the battery B1 through the first diode 21. Also, when the shunt switch 41 conducts, current flows from the battery B2 through the shunt circuit 40 to the bus bar G.

[0071] On the other hand, when the wiring switch 10 switches from the off state to the on state, the second diode switch SW2 and the shunt switch 41 are opened. Then, current flows from the battery B1 and the battery B2 to the bus bar G.

[0072] Note that the method of controlling the current value flowing through the battery B1 during the discharge of the battery unit is the same as the method of controlling the current flowing through the battery B1 during the charging of the battery unit, except that the direction of the flowing current is reversed.

[0073] <Effect of the First Embodiment> With such a battery unit charge / discharge control device 100, the battery current control unit 62 switches the on / off state of the wiring switch 10 based on the current value flowing through the battery B1, so that currents corresponding to the capacities of the batteries B1 and B2 flow through the batteries B1 and B2, respectively. Thus, it is possible to prevent some of the batteries from being overcharged or overdischarged. Therefore, it is possible to charge and discharge the battery unit while suppressing some of the batteries B1 from being overcharged or overdischarged in a state where a plurality of batteries B1 and B2 having different capacities or resistances are mixed and connected in series. Also, according to the battery unit charge / discharge control device 100 in the present embodiment, there is no need to group the batteries, so that complicated and time-consuming analyses such as battery history analysis or battery degradation analysis can be made unnecessary. As a result, the man-hours required for designing or constructing the battery unit can be reduced. In addition, since there is no need to group the batteries, there is no need to select a plurality of batteries having different capacities or resistances, such as the reuse battery constituting the battery unit, from within the same group. As a result, the degree of freedom in selecting the batteries constituting the battery unit when designing or constructing the battery unit can be increased as compared with the prior art.

[0074] Further, when the wiring switch 10 switches from the on state to the off state, the current flowing between the bus bar G and the battery B1 is cut off, while the current flowing through the diode 20 can be gradually decreased via the reactor 30. Further, when the wiring switch 10 switches from the off state to the on state, a current flows between the bus bar G and the battery B1, and the reactor 30 can gradually increase the current flowing between the bus bars G. As a result, a rapid change in current when the wiring switch 10 switches between the on state and the off state can be suppressed, so that a failure of the battery B1 or the wiring switch 10 due to the current change can be prevented.

[0075] And since the feedback control unit 621 controls the current flowing through the battery B1 to reach the target value based on the first threshold value and the second threshold value having different magnitudes, the current value flowing through the battery can be controlled near the target value of the current of the battery B1 set between the first threshold value and the second threshold value. As a result, it is possible to more surely prevent the battery B1 from being overcharged or overdischarged.

[0076] In addition, in the off state of the wiring switch 10, since a current flows between the bus bars G via the shunt circuit 40, even when the wiring switch 10 is in the off state, the battery B2 connected in series with the battery B1 continues to be charged or discharged. As a result, charging or discharging of the plurality of batteries B1 and B2 constituting the battery unit can be completed almost simultaneously.

[0077] Furthermore, when the wiring switch 10 changes from the off state to the on state and the shunt circuit 40 is electrically disconnected from the bus bar G, a current flows from the shunt reactor 42 to the shunt diode 43 in the shunt circuit 40. As a result, when the wiring switch 10 is turned off again and the shunt circuit 40 is electrically connected to the bus bar G, a large current from the bus bar G can be prevented from flowing suddenly into the shunt circuit 40, and the shunt switch 41 can be protected.

[0078] Moreover, since the battery unit charge / discharge control device 100 includes the capacitor 50, charges are accumulated in the capacitor 50 by the current flowing from the bus bar G during charging of the battery unit. Therefore, when the wiring switch 10 is switched from the on state to the off state and the battery B1 is disconnected, the capacitor 50 can hold the voltage corresponding to the electromotive force of the battery B1.

[0079] <Second Embodiment of the Present Invention> Next, a second embodiment of the present invention will be described.

[0080] <Overall Configuration of Battery Unit Charge / Discharge Control Device> In the second embodiment, the configuration in which a plurality of batteries B are connected in parallel to the bus bar G is different from that of the first embodiment. Also, in the second embodiment, the configuration in which the battery unit charge / discharge control device 200 does not include the shunt circuit 40 and the capacitor 50 is different from the configuration of the battery unit charge / discharge control device 100 in the first embodiment. In addition, in the second embodiment, the control mechanism 60 of the battery unit charge / discharge control device 200 does not include the shunt switch control unit 623, which is different from the control mechanism 60 of the battery unit charge / discharge control device 200 in the first embodiment. Other configurations are the same as those of the battery unit charge / discharge control device 100 in the first embodiment.

[0081] Next, a method for controlling charging and discharging of a battery unit using the battery unit charging and discharging control device 200 in the second embodiment will be described with reference to FIGS. 6 to 9. Here, when the resistances of the respective batteries constituting the battery unit are different, the target value of the current flowing through the battery B is represented by Equation (2) below.

[0082]

Equation

[0083] Here, I set is the target value of the current flowing through the battery B, a is the shunt ratio, and I total is the total current flowing into the entire battery unit. When the currents flowing through the respective batteries constituting the battery unit are made equal, the shunt ratio a is represented by the reciprocal of the number of batteries connected in parallel.

[0084] <Charging control method> As shown in FIG. 6, a plurality of batteries B are connected in parallel to the bus bar G to design a battery unit. Note that the plurality of batteries B are, for example, reuse batteries, and the resistances of the plurality of batteries B are different from each other.

[0085] As shown in FIG. 7(a), by turning on the wiring switch 10, current is supplied from the bus bar G to the battery unit, and charging of the battery unit is started. In FIG. 7(a), the first diode switch SW1 is conducting, and the second diode switch SW2 is open.

[0086] Also, in FIG. 7(a), the current acquisition unit 61 acquires the current value flowing through the battery B, and the feedback control unit 621 compares the magnitude relationship between the acquired current value and the first threshold value or the second threshold value. Note that, as shown in FIG. 7(b), a current greater than the first threshold value is flowing through the battery B.

[0087] When the current value flowing through the battery B becomes equal to or greater than the first threshold value, as shown in FIG. 8(a), the PWM signal generation unit 622 outputs an off signal in accordance with a command from the feedback control unit 621, and the wiring switch 10 is turned off. As a result, the current from the bus bar G is no longer supplied to the battery B.

[0088] Also, when the first diode switch SW1 is turned on, a current flows through the battery B1 via the first diode 21. Then, due to the reactor 30, the current flowing through the battery B1 via the first diode 21 gradually decreases. Therefore, as shown in FIG. 8(b), the current flowing through the battery B1 gradually decreases with the passage of time.

[0089] When the current value flowing through the battery B becomes equal to or less than the second threshold value, as shown in FIG. 9(a), the PWM signal generation unit 622 outputs an on signal in accordance with a command from the feedback control unit 621, and the wiring switch 10 is turned on. As a result, as shown in FIG. 9(a), the current supplied from the bus bar G flows through the battery B. Consequently, as shown in FIG. 9(b), the current flowing through the battery B gradually increases with the passage of time.

[0090] Until the charging of the battery unit is completed, the battery unit charge / discharge control device 100 compares the magnitude relationship between the current value and the first threshold value or the second threshold value in the same manner as the method shown in FIGS. 3 to 5, and controls the opening and closing of the wiring switch 10.

[0091] <Discharge control method> Next, a discharge control method for the battery unit using the battery unit charge / discharge control device 200 in the second embodiment will be described.

[0092] A battery unit composed of batteries B1 and B2 is connected in parallel to a bus bar G by a battery wiring L. Then, by turning on the wiring switch 10, current flows from the battery unit to the bus bar G, and the discharge of the battery unit is started. When the battery unit is discharged, current flows from the battery unit to the bus bar G, so the direction of the current during discharge of the battery unit is reversed compared to when the battery unit is charged.

[0093] When the wiring switch 10 is switched from the on state to the off state, the second diode switch SW2 is turned on, and current flows from the battery B1 through the first diode 21.

[0094] On the other hand, when the wiring switch 10 is switched from the off state to the on state, the second diode switch SW2 is opened. Then, current flows from the batteries B1 and B2 to the bus bar G.

[0095] Note that the method of controlling the current value flowing through the battery B1 during discharge of the battery unit is only that the direction of the current flowing through the battery B1 during discharge of the battery unit is reversed compared to the method of controlling the current flowing through the battery B1 during charging of the battery unit, and the rest is the same.

[0096] <Effects of the Second Embodiment> According to the battery unit charge / discharge control device 100 of the second embodiment, the battery current control unit 62 switches the on / off state of the wiring switch 10 based on the current value, so that current corresponding to the resistance of the plurality of batteries B flows through the plurality of batteries B. Therefore, when a plurality of batteries B are connected in parallel to the bus bar G, overcurrent caused by differences in the resistance of each battery B can be prevented. Particularly in the case of a reuse battery, since the deterioration states of the batteries are different, the resistances of the respective batteries often differ. Therefore, according to the battery unit charge / discharge control device 100 of the second embodiment, batteries B having different deterioration states can be mixed and connected in parallel, so that the capacity of the battery unit can be easily expanded.

[0097] <Third Embodiment of the Present Invention> Next, the third embodiment of the present invention will be described.

[0098] <Overall Configuration of Battery Unit Charge / Discharge Control Device> In the third embodiment, first, the configuration in which the feedback control unit 621 does not have a threshold value is different. Also, the PWM signal generation unit 622 outputs a PWM signal having a duty ratio corresponding to the output of the feedback control unit 621, and when the PWM signal is on, the wiring switch 10 is turned on, and when the PWM signal is off, the wiring switch 10 is turned off. This configuration is different from the first and second embodiments. Here, the PWM signal output by the PWM signal generation unit 622 has a duty ratio such that the current value flowing through the battery B1 becomes equal to the target value of the current of the battery B1.

[0099] Specifically, the PWM signal generation unit 622 has a plurality of duty ratios with different magnitudes. When the current value flowing through the battery B1 is greater than the target value of the current of the battery B1, the PWM signal generation unit 622 outputs a PWM signal with a small duty ratio. However, the duty ratio is set so as not to be less than 0.

[0100] On the other hand, when the current value flowing through the battery B1 is less than the target value of the current of the battery B1, the PWM signal generation unit 622 outputs a PWM signal with a large duty ratio. However, the duty ratio is set so as not to be greater than 1.

[0101] In the third embodiment, the shunt switch control unit 623 outputs an inverted signal, which is a signal obtained by inverting the on and off states of the PWM signal output by the PWM signal generation unit 622, and conducts the shunt switch 41 when the inverted signal is on, and opens the shunt switch 41 when the inverted signal is off.

[0102] <Charge Control Method> Next, a charging control method using the battery unit charge / discharge control device in the third embodiment will be described. In the third embodiment, the plurality of batteries constituting the battery unit may be connected in series to the bus bar G, may be connected in parallel, or a mixture of these may be used.

[0103] By turning on the wiring switch 10, current is supplied from the bus bar G to the battery unit, and charging of the battery unit is started. Here, the first diode switch SW1 is conducting, and the second diode switch SW2 is open.

[0104] Also, the current acquisition unit 61 acquires the value of the current flowing through the battery B, and the feedback control unit 621 controls the current so that the acquired current value becomes the target value of the current flowing through the battery B.

[0105] When the value of the current flowing through the battery B is greater than the target value of the current of the battery B, the PWM signal generation unit 622 outputs a PWM signal with a small duty ratio. As a result, the time during which the wiring switch 10 is in the off state becomes longer, and it becomes difficult for the current from the bus bar G to be supplied to the battery B.

[0106] Also, when the first diode switch SW1 is turned on, current flows through the battery B1 via the first diode 21. Then, due to the reactor 30, the current flowing through the battery B1 via the first diode 21 gradually decreases, so the current flowing through the battery B1 gradually becomes smaller over time.

[0107] On the other hand, when the value of the current flowing through the battery B is smaller than the target value of the current of the battery B, the PWM signal generation unit 622 outputs a PWM signal with a large duty ratio. As a result, the time during which the wiring switch 10 is in the on state becomes longer, and it becomes easier for the current from the bus bar G to be supplied to the battery B.

[0108] The battery unit charge / discharge control device according to the third embodiment repeatedly outputs PWM signals with different duty ratios so that the current value flowing through the battery B reaches the target value until the charging of the battery unit is completed.

[0109] <Discharge control method> Next, a discharge control method using the battery unit charge / discharge control device according to the third embodiment will be described. In the third embodiment, the plurality of batteries constituting the battery unit may be connected in series to the bus bar G, may be connected in parallel, or may be a mixture of these.

[0110] By turning on the wiring switch 10, current flows from the battery unit to the bus bar G, and the discharge of the battery unit is started. When the battery unit is discharged, current flows from the battery unit to the bus bar G, so the direction of the current during discharge of the battery unit is reversed compared to when the battery unit is charged.

[0111] When the wiring switch 10 is switched from the on state to the off state, the second diode switch SW2 is turned on, and current flows from the battery B1 through the first diode 21.

[0112] On the other hand, when the wiring switch 10 is switched from the off state to the on state, the second diode switch SW2 is opened. Then, current flows from the battery B1 and the battery B2 to the bus bar G.

[0113] Note that the method of controlling the current value flowing through the battery B1 during discharge of the battery unit is the same as the method of controlling the current flowing through the battery B1 during charging of the battery unit, except that the direction of the flowing current is reversed.

[0114] <Other embodiments> Note that the present invention is not limited to the above-described embodiments.

[0115] In the first and second embodiments, the battery B constituting the battery unit was a reusable battery, but the present invention is not limited to this, and the battery B may be, for example, a battery before being mounted on an electric vehicle or a hybrid vehicle.

[0116] In the first and second embodiments, the plurality of batteries B constituting the battery unit were connected to the bus bar G either in series or in parallel, but the plurality of batteries B may be connected to the bus bar G in a state where series and parallel connections are mixed.

[0117] In the first and second embodiments, the PWM signal generation unit 622 switched the on / off state of the wiring switch 10 by PWM control, but the present invention is not limited to PWM control, and the on / off state of the wiring switch 10 may be switched by other control methods.

[0118] In the first and second embodiments, the battery unit charge / discharge control device 100 was configured to control both the charging and discharging of the battery unit, but it may be configured to control only either the charging or the discharging of the battery unit. For example, when the battery unit charge / discharge control device 100 controls only the charging of the battery unit, the second diode 22 and the second diode switch SW2 can be made unnecessary. Further, in the battery unit charge / discharge control device 100 of the first embodiment, the second shunt diode 43b and the second shunt diode switch 44b can be made even more unnecessary.

[0119] On the other hand, for example, when the battery unit charge / discharge control device 100 controls only the discharging of the battery unit, the first diode 21 and the first diode switch SW1 can be made unnecessary. Further, in the battery unit charge / discharge control device 100 of the first embodiment, the first shunt diode 43a and the first shunt diode switch 44a can be made even more unnecessary.

[0120] In the first embodiment, in the case of a battery unit composed of three or more batteries B, it is sufficient that there is at least one battery through which current flows via the diode 20. Also, in this case, it is sufficient that there is at least one battery through which current flows from the shunt circuit 40.

[0121] In the first embodiment, the battery unit charge / discharge control device 100 has a configuration including the diode 20, the reactor 30, the shunt circuit 40, and the capacitor 50. However, in order to cause a current corresponding to the capacity of each battery B to flow through each battery B, these are not essential configurations. That is, the battery unit charge / discharge control device 100 may include at least the wiring switch 10, the current acquisition unit 61, and the battery current control unit 62.

[0122] Also, in the second embodiment, the battery unit charge / discharge control device 100 has a configuration including the diode 20 and the reactor 30. However, in order to cause a current corresponding to the resistance of each battery B to flow through each battery B, these are not essential configurations. That is, the battery unit charge / discharge control device 100 may include at least the wiring switch 10, the current acquisition unit 61, and the battery current control unit 62.

[0123] In the first embodiment and the second embodiment, the PWM signal generation unit 622 compares the current value flowing through the battery B with a threshold value. In the third embodiment, the PWM signal generation unit 622 outputs a PWM signal having a duty ratio corresponding to the output of the feedback control unit 621. However, these controls may be combined.

[0124] In addition, various modifications and combinations of embodiments may be made as long as they do not depart from the spirit of the present invention.

Explanation of Reference Numerals

[0125] 100 ··· Battery unit control device 10 ··· Wiring switch 20 ··· Reactor 30 ··· Diode 40 ··· Shunt circuit 41 ··· Shunt switch 42 ··· Shunt reactor 43 ··· Shunt diode 44 ··· Shunt diode switch 50 ··· Capacitor 60 ··· Control mechanism 61 ··· Current acquisition unit 62 ··· Battery current control unit G ··· Busbar L ··· Wiring B ··· Battery

Claims

1. A battery unit charge / discharge control device for controlling charging or discharging of a battery unit connected to a bus bar by a battery wiring provided with a plurality of batteries having different resistances or capacitances, a wiring switch provided in the battery wiring and switching between an on state in which the battery and the bus bar are electrically connected and an off state in which the battery and the bus bar are disconnected, a current acquisition unit that acquires a current flowing through the battery, and a battery current control unit that switches on / off of the wiring switch based on the current value acquired by the current acquisition unit to cause a current corresponding to the resistance or capacitance of the plurality of batteries to flow through the plurality of batteries. A battery unit charge / discharge control device.

2. a reactor interposed between the wiring switch and the battery, and a diode connected in parallel with the battery, wherein in the off state, current flows through the diode via the reactor, and in the on state, current flows between the bus bars via the wiring. The battery unit charge / discharge control device according to claim 1.

3. The battery current control unit turns the wiring switch to the off state when the current value is greater than a predetermined first threshold value, and turns the wiring switch to the on state when the current value is less than a second threshold value which is a threshold value smaller than the first threshold value. The battery unit charge / discharge control device according to claim 1 or 2.

4. The battery unit charge / discharge control device according to any one of claims 1 to 3, wherein the plurality of batteries are connected to the bus bar in series.

5. further comprising a shunt circuit having one end connected to the wiring between the wiring switch and the battery and the other end connected between the battery and the bus bar, wherein in the on state, current flows between the bus bars via the wiring, and in the off state, current flows between the bus bars via the shunt circuit. The battery unit charge / discharge control device according to claim 4.

6. The shunt circuit includes a shunt switch that electrically connects and disconnects the battery wiring and the shunt circuit, a shunt reactor connected to the shunt switch, and a shunt diode provided in parallel with the shunt reactor. The battery unit charge / discharge control device according to claim 5, wherein in the on state, the shunt switch is opened and current flows from the shunt reactor to the shunt diode.

7. The battery unit charge / discharge control device according to any one of claims 5 or 6, further comprising a capacitor provided between the bus bar and the wiring switch and connected in parallel with the shunt circuit.

8. The battery unit charge / discharge control device according to any one of claims 1 to 3, wherein a plurality of the batteries are connected in parallel to the bus bar.

9. A charge / discharge control method using a battery unit charge / discharge control device for controlling charging or discharging of a battery unit connected to a bus bar by a battery wiring provided with a plurality of batteries having different resistances or capacitances, wherein the battery unit charge / discharge control device comprises a wiring switch provided in the battery wiring and switchable between an on state in which the battery and the bus bar are electrically connected and an off state in which the battery and the bus bar are disconnected, and the charge / discharge control method acquires a current value flowing through the battery, and by switching the on / off of the wiring switch based on the acquired current value, causes a current corresponding to the resistance or capacitance of the plurality of batteries to flow through the plurality of batteries.

10. A charge / discharge control program used in a battery unit charge / discharge control device for controlling charging or discharging of a battery unit connected to a bus bar by a battery wiring provided with a plurality of batteries having different resistances or capacitances, wherein the battery unit charge / discharge control device comprises a wiring switch provided in the battery wiring and switchable between an on state in which the battery and the bus bar are electrically connected and an off state in which the battery and the bus bar are disconnected, and the charge / discharge control program causes a computer to function as a current acquisition unit that acquires a current value flowing through the battery, and a battery current control unit that causes a current corresponding to the resistance or capacitance of the plurality of batteries to flow through the plurality of batteries by switching the on / off of the wiring switch based on the current value acquired by the current acquisition unit.

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