JP2003153460A - Charging/discharging controller of storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charger/discharger of a storage battery comprising three or more of unit storage batteries connected in series in which a specific unit storage battery can be charged/discharged concentrically while avoiding increase of the circuit scale. SOLUTION: At the time of charging a cell 10a, an FET switch 16 is connected with an intermediate joint 14ab to turn on an FET 24 and when a current to a reactor 17 reaches a specified level, the FET 24 is turned off. Consequently, a parasitic diode 22 is turned on naturally and a charging current flows to the cell 10a being charged. When a cell 10b is charged, the FET switch 16 is connected with an intermediate joint 14bc to turn on the FET 24. When the current to the reactor 17 reaches a specified level, the FET 24 is turned off. Consequently, the parasitic diode 22 is turned on naturally and a charging current flows to the cells 10a and 10b (first operation). Upon elapsing a specified time, the FET switch 16 is connected with the intermediate joint 14ab to turn on an FET 21. When the current to the reactor 17 reaches a specified level, the FET 21 is turned off, a parasitic diode 25 is turned on, and then a charging current flows to the cells 10b-10d based on the electromotive force thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge / discharge control device for a power storage device in which three or more unit power storage devices are connected in series between positive and negative output terminals for charging and discharging.

[0002]

2. Description of the Related Art For example, a power battery incorporated in an electric vehicle has a plurality of unit secondary batteries connected in series to secure a high voltage. When charging such an assembled battery, it is unavoidable that the charging state of each battery varies due to variations in the capacity and internal impedance of each unit secondary battery. However, since the unit secondary batteries are connected in series, charging currents of the same magnitude flow in each battery, and variations in the charging state appear as variations in the terminal voltage, which may cause overcharging of some batteries. I will invite you.

As an example of preventing such overcharge of some secondary batteries, a shunt regulator system as shown in FIG. 8 has been conventionally used. This is because the transistor 2 is connected in parallel with each unit secondary battery 1 and the current i
Can be bypassed to the transistor 2 and the battery 1
When the charging of the battery advances and its terminal voltage rises, this is detected and the bypass current ib is increased to throttle the charging current ic to the battery 1 to prevent its overcharging.

[0004]

However, in the above configuration, since the product of the bypass current ib flowing into the transistor 2 and the terminal voltage vc in each unit secondary battery 1 becomes a loss, there is a drawback that the charging efficiency is poor. . Further, not only the charging efficiency is poor, but even if the unit secondary battery 1 is fully charged and the bypass current ib flows through the transistor 2, the charging current ic of the other uncharged unit secondary battery 1 is the current. Since it cannot be increased beyond i (ic ≤
i) As for the completion of the entire charging, there is no choice but to wait for the completion of the charging of the insufficiently charged unit secondary battery 1, and the charging time cannot be shortened.

In order to solve such a problem, there has been proposed a structure in which an individual charging circuit is provided for each unit secondary battery, but this increases the circuit scale according to the number of unit secondary batteries and Problems arise in terms of cost and downsizing of the device.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a specific unit power storage device while avoiding an increase in circuit scale for a power storage device in which three or more unit power storage devices are connected in series. In view of the above, an object of the present invention is to provide a charging / discharging device for a power storage device that can be intensively charged or discharged.

[0007]

In order to achieve the above object, a charge / discharge control device for a power storage device according to the invention of claim 1 is configured so that three or more unit power storage devices are connected in series between positive and negative output terminals. A charging / discharging control device for a power storage device to be discharged, wherein a reactor and a switch element capable of selectively connecting one end side of the reactor to each connection point between each unit power storage device,
For the pair of switching circuits connected between the other end of the reactor and each of the positive and negative terminals, and for each terminal unit power storage device located at both ends of the power storage device, the other unit power storage device adjacent to it By connecting one end side of the reactor to the connection point and opening the switching circuit connected to the unit power storage device excluding the terminal unit power storage device after turning it on, the terminal unit power storage is performed by the electromagnetic energy stored in the reactor. A current is caused to flow in the charging direction to the device, and for each intermediate unit power storage device other than the terminal unit power storage device, one end of the reactor is connected to one of the connection points at both ends of the intermediate unit power storage device. , A switch connected to a unit power storage device group that does not include the intermediate unit power storage device of the two unit power storage device groups divided by the connection. By opening the circuit after turning it on, the electromagnetic energy stored in the reactor performs the first operation of flowing a current in the charging direction to the unit power storage device group including the intermediate unit power storage device, and then the intermediate unit. One end side of the reactor is connected to a connection point on the opposite side to the first operation among the connection points on both ends of the power storage device, and the intermediate unit power storage device is included in the two unit power storage device groups divided from the connection. The second operation in which the switching circuit connected to the unit power storage device group that does not exist is turned on and then opened to cause a current to flow in the charging direction to the unit power storage device group including the intermediate unit power storage device by the electromagnetic energy stored in the reactor. And a control means for controlling the pair of switching circuits so as to perform.

A charge / discharge control device for a power storage device according to a second aspect of the present invention is a charge / discharge control device for a power storage device in which three or more unit power storage devices are connected in series between positive and negative output terminals to charge and discharge. A reactor, a switch element that can selectively connect one end of the reactor to each connection point between the unit power storage devices, and a pair of switching devices connected between the other end of the reactor and each of the positive and negative terminals. Regarding the circuit and each terminal unit power storage device located at both ends of the power storage device, one end side of the reactor is connected to a connection point with another unit power storage device adjacent to the circuit, and a switching circuit connected to the terminal unit power storage device is connected. By opening this after turning it on, the electromagnetic energy stored in the reactor causes a current to flow in the charging direction to the unit power storage device excluding the terminal unit power storage device. For each intermediate unit power storage device other than the terminal unit power storage device, one end side of the reactor is connected to one of the connection points at both ends of the intermediate unit power storage device, and two unit power storage devices separated from the connection are connected. By turning on the switching circuit connected to the unit power storage device group including the intermediate unit power storage device of the group and then opening the switching circuit, the unit energy storage device group not including the intermediate unit power storage device is generated by the electromagnetic energy stored in the reactor. The first operation of passing a current in the charging direction is performed, and then one end of the reactor is connected to the connection point on the opposite side of the first operation among the connection points at both ends of the intermediate unit power storage device, and After the switching circuit connected to the unit power storage device group including the intermediate unit power storage device of the two divided unit power storage device groups is turned on, the switching circuit is opened. And a control unit that performs a control operation of the switch element and the pair of switching circuits so as to perform the second operation of flowing a current in the charging direction to the unit power storage device group not including the intermediate unit power storage device by the electromagnetic energy stored in the reactor. It is characterized by having and.

According to a third aspect of the present invention, in the charge / discharge control device for a power storage device according to the first aspect, the control means sets the difference between the maximum voltage and the minimum voltage of the voltages of the unit power storage devices to be equal to or more than a predetermined value. The feature is that the control operation is performed on the unit power storage device exhibiting the minimum voltage on the condition that

According to a fourth aspect of the present invention, in the charge / discharge control device for a power storage device according to the second aspect, the control means sets the difference between the maximum voltage and the minimum voltage of the voltages of each unit power storage device to a predetermined value or more. The feature is that the control operation is performed for the unit power storage device exhibiting the maximum voltage on condition that the maximum voltage has been reached.

According to a fifth aspect of the present invention, in the charge / discharge control device for a power storage device according to the first aspect, the control means has a minimum voltage among the voltages of the unit power storage devices and an average value of the voltages of the unit power storage devices. The feature is that the control operation is performed on the unit power storage device exhibiting the minimum voltage on condition that the difference between and is greater than or equal to a predetermined value.

According to a sixth aspect of the present invention, in the charge / discharge control device for a power storage device according to the second aspect, the control means has a maximum voltage of the voltages of the unit power storage devices and an average value of the voltages of the unit power storage devices. The feature is that the control operation is performed on the unit power storage device exhibiting the maximum voltage on condition that the difference between and is greater than or equal to a predetermined value.

[0013]

<Advantages and effects of the invention><Invention of claim 1> According to the configuration of claim 1, when the unit electricity storage device to be charged intensively is an end unit electricity storage device located at both ends of the electricity storage device, it is adjacent to it. One end side of the reactor is connected to a connection point with another matching unit power storage device, and a switching circuit connected to the unit power storage device excluding the terminal unit power storage device is turned on. As a result, a current flows from the unit power storage device other than the terminal unit power storage device to the reactor. After that, when the switching circuit is turned off, an electromotive force that causes a current to flow in the same direction is induced by the electromagnetic energy stored in the reactor, so that the terminal unit power storage device is based on the electromotive force. A current flows in the charging direction.
In this way, the current flows in the charging direction only to the unit power storage devices that are desired to be intensively charged, and thus it is possible to perform the intensive charging.

On the other hand, when the unit power storage device to be centrally charged is an intermediate unit power storage device other than the terminal unit power storage device,
A unit power storage device in which one end of the reactor is connected to one of the connection points at both ends of the intermediate unit power storage device and the intermediate unit power storage device is not included in the two unit power storage device groups divided from the connection. The switching circuit connected to the group is turned on and then opened. As a result, a current is caused to flow from the unit power storage device group that does not include the intermediate unit power storage device to the reactor, and the unit power storage device group including the intermediate unit power storage device is generated based on the electromotive force generated by the electromagnetic energy stored in the reactor. A current flows in the charging direction (first operation).

Next, one end side of the reactor is connected to a connection point on the opposite side of the first operation among the connection points on both ends of the intermediate unit power storage device, and two unit power storage device groups separated from the connection. Among them, the switching circuit connected to the unit power storage device group that does not include the intermediate unit power storage device is turned on and then opened. This causes a current to flow from the unit power storage device group that does not include the intermediate unit power storage device to the reactor, and charges the unit power storage device group that includes the intermediate unit power storage device based on the electromotive force generated by the electromagnetic energy stored in the reactor. A current flows in the direction (second operation).
In this way, in the first and second operations, the current always flows in the charging direction in the unit power storage device that is desired to be charged intensively, and thus it is possible to perform the intensive charge. With such a configuration, a specific unit power storage device can be centrally charged with a simple configuration without providing a separate charging circuit for each unit power storage device.

<Invention of Claim 2> According to the configuration of Claim 2, when the unit power storage device to be discharged intensively is a terminal unit power storage device located at both ends of the power storage device, another unit adjacent to it One end of the reactor is connected to a connection point with the power storage device, and a switching circuit connected to the terminal unit power storage device is turned on. This causes a current to flow from the terminal unit power storage device to the reactor. After that, when the switching circuit is turned off, an electromotive force that causes a current to flow in the same direction is induced by the electromagnetic energy stored in the reactor, so that the terminal unit power storage device is based on the electromotive force. Current flows in the charging direction of the unit power storage device except for. In this way, the current flows in the discharge direction only in the unit power storage devices that are desired to be discharged in a concentrated manner, so that it is possible to discharge in a concentrated manner.

On the other hand, in the case where the unit power storage device to be intensively discharged is an intermediate unit power storage device other than the terminal unit power storage device,
One end side of the reactor is connected to either one of the connection points at both ends of the intermediate unit power storage device, and a unit power storage device group including the intermediate unit power storage device in the two unit power storage device groups divided from the connection. The switching circuit connected to is turned on and then opened. Accordingly, a current is caused to flow from the unit power storage device group including the intermediate unit power storage device to the reactor, and the unit power storage device group not including the intermediate unit power storage device is generated based on the electromotive force generated by the electromagnetic energy stored in the reactor. A current flows in the charging direction (first operation).

Next, one end side of the reactor is connected to a connection point on the opposite side to the first operation among the connection points on both ends of the intermediate unit power storage device, and two unit power storage device groups separated from the connection. The switching circuit connected to the unit power storage device group including the intermediate unit power storage device is turned on, and then the switching circuit is opened. As a result, a current flows from the unit power storage device group including the intermediate unit power storage device to the reactor, and the unit power storage device group not including the intermediate unit power storage device is charged based on the electromotive force generated by the electromagnetic energy stored in the reactor. A current flows in the direction (second operation). In this way, in the first and second operations, the current always flows in the discharge direction in the unit power storage device that wants to be discharged intensively, so that it is possible to discharge intensively.
With such a configuration, it is possible to intensively discharge a specific unit power storage device.

<Invention of Claims 3 to 6> Claim 3
According to the configuration, the condition is that the difference between the maximum voltage and the minimum voltage among the voltages of the unit power storage devices is equal to or more than a predetermined value,
The control operation described in claim 1 is performed by the control means for the unit power storage device exhibiting the minimum voltage. On the other hand, claim 4
According to the configuration, the condition is that the difference between the maximum voltage and the minimum voltage among the voltages of the unit power storage devices is equal to or more than a predetermined value,
The control operation described in claim 2 is performed by the control means for the unit power storage device having the maximum voltage.

Further, according to the structure of claim 5, on condition that the difference between the minimum voltage of the voltage of each unit power storage device and the average value of the voltage of each unit power storage device is equal to or more than a predetermined value, The control operation described in claim 1 is performed by the control means for the unit power storage device exhibiting the minimum voltage. On the other hand, according to the configuration of claim 6, when the difference between the maximum voltage of the voltage of each unit power storage device and the average value of the voltage of each unit power storage device is equal to or more than a predetermined value, the maximum voltage The control operation according to claim 2 is performed by the control means for the unit power storage device indicating.

With these configurations, the voltage difference between the unit power storage devices is controlled to be within a predetermined range.
Therefore, the voltages of the unit power storage devices can be equalized.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> A first embodiment of the present invention will be described with reference to FIGS. In this embodiment, four cells 10 of a lithium ion battery as a unit secondary battery (corresponding to the “unit power storage device” of the present invention.
Then, reference numerals 10a, 10b, 10c and 10d. ) Is connected in series between both output terminals 11 and 12 (corresponding to the "electric storage device" of the present invention). Each cell 10 has the same specifications.

Each terminal voltage of each cell 10 is measured by the voltage detection circuit 13 at any time, and each measurement result is A /
It is D-converted and given to the CPU 15. Also, each cell 1
One end of the reactor 17 is selectively connected to each of the intermediate connection points 14ab, 14bc, 14cd of 0 via the FET switch 16, for example. A resistor 18 for detecting a current flowing in the reactor 17 is connected between the FET switch 16 and one end of the reactor 17, and the resistor 18 is connected to the resistor 18.
The current flowing in the CPU 15 is measured by the current detection circuit 19 at any time, and the measurement result is also A / D converted to the CPU 15
Given to. The other end of the reactor 17 is connected to the positive electrode output terminal 1 via the switching circuit 20 (the FET 21 and its parasitic diode 22 are shown in the figure).
1 and is also connected to the negative output terminal 12 via the switching circuit 23 (the FET 24 and its parasitic diode 25 are shown in the figure).

Each FET 2 of the switching circuits 20 and 23
Both 1 and 24 are, for example, N-channel type,
When T21 is turned on, the cell 10 connected to it
Current to the reactor 17 in the direction of arrow A in the figure, and
When the ET24 is turned on, the cell 10 connected to it
From this, a current is passed through the reactor 17 in the direction of arrow B in the figure. Since the parasitic diodes 22 and 25 are turned on when the anode-side potential exceeds the cathode-side potential, both switching circuits 20 and 23 allow current to flow freely upward in the drawing and FETs 21 and 24 downward in the drawing. Only when it is turned on, current will flow. The CPU 15 drives and controls the FET switch 16 and the gate control circuit 26 based on the measurement results from the voltage detection circuit 13 and the current detection circuit 19, as will be apparent from the operation description given below. FET
The gate potentials of 21 and 24 are controlled by the gate control circuit 26.

Now, regarding the operation of the above configuration, the FET switch 16 and both switching circuits 2 shown in FIG. 2 and FIG.
This will be described with reference to the operation state tables of 0 and 23. In addition, the fraction in the figure shows the ratio of the current flowing through each cell 10 to the average value of the current flowing through the reactor 17, and the plus means the charging direction and the minus means the discharging direction, respectively.

When charging the assembled battery, the output terminals 11 and 12
A charging power supply is connected between them to supply the charging current. The charging current flows through each cell 10 in series, and the charging of each cell 10 gradually progresses. However, the state of charge of each cell 10 may vary due to variations in the remaining capacity of each cell 10, the internal impedance, and the like, and the terminal voltage may not increase in the same manner.

<Charging Operation for Cells 10a, 10d (Terminal Unit Energy Storage Device)> Here, for example, the terminal voltage of the cell 10a (corresponding to the "terminal unit energy storage device" of the present invention) located at the terminal of the assembled battery is Each of the other cells 10b, 10
If the difference between the terminal voltage of the cell showing the maximum voltage of c and 10d exceeds a predetermined value, the CPU 15 starts the following operation to intensively charge the cell 10a (claim 3). Corresponding to the configuration).

As shown in FIG. 2, when the cell 10a is intensively charged, the FET switch 16 is connected to the intermediate connection point 14ab between the cells 10a and 10b, and the gate control circuit 26 causes the switching circuit 23 to switch.
FET 24 (corresponding to “a switching circuit connected to the unit power storage device excluding the terminal unit power storage device” of the present invention)
Is turned on. At the moment when the FET 24 is turned on, the reactor 17 has cells 10b, 10c,
A current flows in the direction of arrow B from the 10d side.

When the current detection circuit 19 detects that the current flowing through the reactor 17 has reached a predetermined value, the gate control circuit 26 turns off the FET 24.
Are driven and controlled. Then, the electromagnetic energy stored in the reactor 17 induces an electromotive force that causes a current to flow in the same arrow B direction, and this time the switching circuit 2
Since the parasitic diode 22 of 0 naturally turns on, a charging current flows in the cell 10a to be charged based on the electromotive force thereof. Since the switching operation in which the FET 24 and the parasitic diode 22 are alternately turned on as described above is repeated, the electromagnetic energy stored in the reactor 17 when the FET 24 is turned on is moved to the cell 10a side by turning on the parasitic diode 22. It is used for charging. In such a state, the terminal voltage of the cell 10a is
It continues until the difference between the terminal voltage of the cell showing the maximum voltage among b, 10c, and 10d falls below a predetermined value.

<Charging Operation for Cells 10b and 10c (Intermediate Unit Power Storage Device)> On the other hand, for example, the terminal voltage of the cell 10b (corresponding to the "intermediate unit power storage device" of the present invention) decreases and each of the other cells If the difference between the terminal voltage of the cell that also shows the maximum voltage of 10a, 10c, and 10d exceeds a predetermined value, the CPU 15 starts the following operation to intensively charge the cell 10b.

As shown in FIG. 3, when the cell 10b is intensively charged, first, the FET switch 16 is set to the cell 10b.
The FET 24 of the switching circuit 23 (corresponding to “a switching circuit connected to a unit power storage device group not including the intermediate unit power storage device” of the present invention) is turned on while being connected to the intermediate connection point 14bc between the cell b and the cell 10c. To be done. At the moment when the FET 24 is turned on, the reactor is shown in FIG.
As shown in, current flows in the direction of arrow B from the cells 10c, 10d side.

When the current flowing through the reactor 17 reaches a predetermined value, the gate control circuit 26 is drive-controlled to turn off the FET 24. Then, reactor 1
The electromagnetic energy stored in 7 induces an electromotive force that causes a current to flow in the same arrow B direction, and the parasitic diode 22 of the switching circuit 20 naturally turns on.
A charging current flows through the cells 10a and 10b based on the electromotive force (corresponding to the "first operation" of the present invention).

Then, after a predetermined time has passed, this time FE
The T switch 16 is connected to the intermediate connection point 14ab between the cell 10a and the cell 10b, and the switching circuit 2
0 (corresponding to “a switching circuit connected to a unit power storage device group including the intermediate unit power storage device” of the present invention)
21 is turned on, and at that moment, a current flows in the reactor 17 from the cell 10a side in the arrow A direction. Then, when the current flowing through the reactor 17 reaches a predetermined value, the FET 21 is also turned off, and the electromagnetic energy stored in the reactor 17 induces an electromotive force that causes the current to flow in the same arrow A direction. Since the parasitic diode 25 of the switching circuit 23 naturally turns on, a charging current flows through the cells 10b, 10c, 10d based on the electromotive force thereof (corresponding to the "second operation" of the present invention).

By carrying out the above-mentioned first and second operations, a current always flows in the charging direction in the cell 10b to be charged, so that it becomes possible to perform intensive charging.
In the present embodiment, the average value of the current flowing through the reactor 17 is controlled to be the same level in the first operation and the second operation. That is, the cell 10b to be charged is charged with a current at a rate of 3/4 of the average current value, and the other cells 10a, 10c, 10d are discharged at a rate of 1/4 substantially uniformly. The cycle of each operation is adjusted. Then, the first and second operations as described above are performed by comparing the terminal voltage of the cell 10b with the other cells 10a, 10c, 10
This continues until the difference between the terminal voltage of the cell having the maximum voltage of d and the terminal voltage of the cell falls below a predetermined value.

In order to prevent over-discharging of the cells 10 other than those to be charged, for example, a predetermined time has elapsed from the start of the above operation, or the terminal voltage of the cell showing the lowest voltage among those cells 10 has fallen below a predetermined value. On the condition that it is, the structure which stops the above-mentioned charge / discharge control operation may be added.

As described above, in the present embodiment, the electric energy on the side of the cell 10 other than the charging target can be moved to the charging target cell 10 through the reactor 17 and contribute to the charging, so that the full charging is achieved. Compared to the conventional shunt regulator method, in which a current is simply bypassed to cause a loss, the loss can be significantly reduced. Moreover, regarding the assembled battery including four cells, it is possible to intensively charge the specific cells while avoiding an increase in the circuit scale.

<Second Embodiment> FIGS. 4 and 5 show a second embodiment (corresponding to the invention of claim 2). While the above embodiment has a configuration for charging a specific cell, the present embodiment is different in the control content of the CPU 15 in that it is a configuration for discharging a specific cell, and other points are as described above. It is similar to the first embodiment. Therefore, the same reference numerals as those of the first embodiment are given, duplicated explanations are omitted, and only different points will be explained next.

<Discharging Operation to Cells 10a, 10d (Terminal Unit Energy Storage Device)> For example, the terminal voltage of the cell 10d (corresponding to the "terminal unit energy storage device" of the present invention) located at the terminal of the assembled battery increases. It is assumed that the difference from the average value of the terminal voltage of all cells 10 is equal to or more than a predetermined value. Then, CPU15
Starts the following operation to intensively discharge the cell 10d (corresponding to the configuration of claim 6).

As shown in FIG. 4, the FET switch 16 is connected to the intermediate connection point 14cd, and the gate control circuit 26 controls the switching circuit 23 (corresponding to the "switching circuit connected to the terminal unit power storage device" of the present invention). 1) is turned on, and at that moment, a current flows in the reactor 17 in the direction of arrow B from the cell 10d side as shown in FIG. When the current flowing through the reactor 17 reaches a predetermined value, the FET 24 is turned off, and the electromagnetic energy stored in the reactor 17 induces an electromotive force that tends to cause the current to flow in the same arrow B direction. The parasitic diode 22 turns on naturally. As a result, a discharge current flows in the discharge target cell 10d, and a charge current flows in the other cells 10a, 10b, 10c based on the electromotive force thereof. And
Since the switching operation in which the FET 24 and the parasitic diode 22 are alternately turned on as described above is repeated,
The electromagnetic energy stored in the reactor 17 due to the discharge of the cell 10d when T24 is turned on is transferred to the other cells 10a, 10b, 10c side when the parasitic diode 22 is turned on. Such a state continues until the difference between the terminal voltage of the cell 10d and the average value of the terminal voltages of all the cells 10 falls below a predetermined value.

<Discharging Operation to Cells 10b, 10c (Intermediate Unit Power Storage Device)> On the other hand, for example, the terminal voltage of the cell 10c (corresponding to the "intermediate unit power storage device" of the present invention) rises and all the cells 10 If the difference from the average value of the terminal voltage of is equal to or more than the predetermined value, the CPU 15 starts the following operation to intensively discharge the cell 10c.

As shown in FIG. 5, first, the FET switch 16 is connected to the intermediate connection point 14bc and the switching circuit 23 (the "switching circuit connected to the unit power storage device group including the intermediate unit power storage device" of the present invention). The FET 24 (corresponding to) is turned on. At the moment when the FET 24 is turned on, the cell 10 as shown in FIG.
A current flows in the direction of arrow B from the c and 10d sides. When the current flowing in the reactor 17 reaches a predetermined value, the FET 24 is turned off, and the electromagnetic energy stored in the reactor 17 induces an electromotive force that causes the current to flow in the same arrow B direction, and the parasitic diode 22 of the switching circuit 20.
Turns on naturally. As a result, a discharge current flows in the discharge target cells 10c and 10d, and the other cells 10c are discharged.
A charging current flows through a and 10b based on the electromotive force. (Corresponding to the "first operation" of the present invention).

Next, after a lapse of a predetermined time, this time FE
The T switch 16 is connected to the intermediate connection point 14cd, and the FET 21 of the switching circuit 20 (corresponding to the "switching circuit connected to the unit power storage device group including the intermediate unit power storage device" of the present invention) is turned on, and At the moment, current flows in the reactor 17 in the direction of arrow A from the cells 10a, 10b, 10c side. And reactor 1
When the current flowing through 7 reaches a predetermined value, the FET
21 is turned off, an electromotive force that causes a current to flow in the same arrow A direction is induced by the electromagnetic energy stored in the reactor 17, and the parasitic diode 25 of the switching circuit 23 naturally turns on this time. As a result, a discharge current flows through the discharge target cell 10c and the other cells 10a and 10b, and a charge current flows through the cell 10d discharged in the first operation based on the electromotive force (see the "second operation of the present invention". )).

By carrying out the above-mentioned first and second operations, a current always flows in the discharge target cell 10c in the discharge direction, so that it becomes possible to discharge in a concentrated manner.
Note that, as in the first embodiment, the average value of the current flowing through the reactor 17 is controlled to be at the same level in the first operation and the second operation. That is, the cell 1 to be discharged
0c discharges a current at a rate of 3/4 with respect to the average current value, and the other cells 10a, 10b, 10d are adjusted such that the cycle of each operation is substantially evenly charged at a rate of 1/4. Has been done. Then, the first and second operations as described above indicate the difference between the terminal voltage of the cell 10d and the average value of the terminal voltages of all the cells 10 or the terminal voltage and the minimum voltage of the cell 10 that show the highest voltage. This continues until the difference from the terminal voltage of the cell 10 falls below a predetermined value.

In order to prevent the cells 10 other than the discharge target from being overcharged, for example, a predetermined time has elapsed from the start of the above operation, or the terminal voltage of the cell showing the highest voltage among those cells 10 exceeds a predetermined value. On the condition that it is, the structure which stops the above-mentioned charge / discharge control operation may be added. Furthermore, in order to prevent over-discharge, the cell 10 that exhibits the lowest voltage
A configuration may be added in which the above-mentioned charge / discharge control operation is stopped on the condition that the terminal voltage of is lower than a predetermined value. As described above, in the present embodiment, the electric energy on the side of the discharge target cell 10 can be moved to the other cells 10 via the reactor 17.

<Third Embodiment> FIG. 6 is a circuit diagram showing a third embodiment. In each of the above-described embodiments, the current detection circuit 19 measures the current flowing in the reactor 17 and the operation of each of the switching circuits 20 and 23 is feedback-controlled based on the measurement result. The configuration is different, and other points are the same as in the first embodiment. Therefore, the same reference numerals as those of the first embodiment are given, duplicated explanations are omitted, and only different points will be explained next.

The current flowing through the reactor 17 is determined by the voltage across the cell group connected to the switching circuit to be turned on, and the voltage across the cell group is substantially proportional to the number of cell groups (each cell has the same specifications as in the above embodiment). thing). Also,
How many cells are connected to the switching circuit that is turned on is determined by the connection state of the FET switch 16 that is drive-controlled by the CPU 15. Therefore, even if the current flowing through the reactor 17 is not measured as in the above-described embodiment, the timing of turning on / off each switching circuit is FE.
By PWM control that is determined according to the connection state of the T switch 16, switching control can be performed so that specific cells are centrally charged or discharged as in the above embodiment. Note that FIG. 7 shows the control contents of the switching circuits 20 and 23 by PWM control.

According to this structure, the effect of the present invention can be obtained with a simpler circuit structure than the above structure in which the current of the reactor 17 is measured and fed back for control.

<Other Embodiments> The present invention is not limited to the above-described embodiments. For example, the embodiments described below are also included in the technical scope of the present invention.
Other than the following, various modifications can be made without departing from the scope of the invention. (1) In each of the above-described embodiments, the configuration of charging or discharging the specific cell 10 for the purpose of balancing the terminal voltage of each cell 10 within a predetermined range has been described, but the present invention is not limited to this.
The configuration may be such that the arbitrarily selected cell is intensively charged or discharged regardless of the relationship with the terminal voltage of another cell.

(2) In each of the above-mentioned embodiments, an assembled battery composed of four cells has been described as an example, but the effect of the present invention can be obtained for three or more cells.

(3) In each of the above embodiments, the FETs 21 and 24 are exemplified as the switching circuit, but the invention is not limited to this, and the transistors 17 and 20 and the diodes 18 and 21 are not limited thereto.
It is also possible to use a parallel circuit of, and other switching elements.

(4) In each of the above embodiments, the unit power storage device is a cell of a lithium ion battery, but the present invention is not limited to this, and various secondary batteries such as a lead storage battery or a nickel cadmium secondary battery, or It may be a capacitor, or may be a battery module in which each unit secondary battery is a combination of a plurality of cells.

(5) In each of the above embodiments, one of the FETs 21 (2
Although the parasitic diode 25 (22) of the other side is naturally turned on by the electromotive force generated in the reactor 17 after the on / off operation of 4), each switching circuit 20,
A switching element having a voltage drop smaller than the forward voltage of the parasitic diodes 22 and 25 may be connected in parallel to each of the 23 to control ON / OFF of these. In particular,
For example, FE is provided in each of the switching circuits 20 and 23.
Since T is connected in anti-parallel and each of the parasitic diodes 22 and 25 is turned on, the FET connected to each is turned on and each FET is turned on and off so that a current flows in the charging direction to the cell 10 connected to the FET. is there. Since the voltage drop during the ON operation of the FET is smaller than the forward voltage of the parasitic diodes 22 and 25, the charging efficiency of the cell 10 can be improved accordingly. Alternatively, the above F
Rather than connecting ET in anti-parallel, each parasitic diode 2
At the timing when 2, 25 are turned on, the switching circuit 2
Even if the gate control circuit 26 controls the FETs 21 and 24 of 0 and 23 to be turned on, the same effect can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is an operation diagram of the FET switch and each switching circuit in charging the end cell.

FIG. 3 is an operation diagram of the FET switch and each switching circuit in charging the intermediate cell.

FIG. 4 is a graph of F in discharge of an end cell according to the second embodiment.
Operation diagram of ET switch and each switching circuit

FIG. 5 is an operation diagram of the FET switch and each switching circuit in discharging the intermediate cell.

FIG. 6 is a circuit diagram showing a third embodiment.

FIG. 7 is an operation diagram showing the control contents of the FET switch and each switching circuit.

FIG. 8 is a circuit diagram showing a conventional secondary battery charging circuit.

[Explanation of symbols]

10 (10a, 10b, 10c, 10d) ... cell 11, 12 ... Output terminals 13 ... Voltage detection circuit 14ab, 14bc, 14cd ... Intermediate connection point 16 ... FET switch 17 ... Reactor 18 ... resistance 19 ... Current detection circuit 20, 23 ... Switching circuit 22, 25 ... Parasitic diode 26 ... Gate control circuit 15 ... CPU 21, 24 ... FET

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5G003 AA04 BA03 CA02 CA14 CC04                       FA06 GB04 GC05                 5H030 AA03 AA04 AS20 BB01 BB21                       DD08 FF43 FF44

Claims (6)

[Claims] 1. A charge / discharge control device for a power storage device in which three or more unit power storage devices are connected in series between positive and negative output terminals to charge and discharge, wherein a reactor and one end side of the reactor are connected to each of the unit power storage devices. A switch element that can be selectively connected to each connection point between, a pair of switching circuits connected between the other end of the reactor and each of the positive and negative terminals, and a position at both ends of the power storage device. For each terminal unit power storage device to be connected, one end side of the reactor is connected to a connection point with another unit power storage device adjacent to it, and the switching circuit connected to the unit power storage device excluding the terminal unit power storage device is turned on. By opening this after operating, the electromagnetic energy stored in the reactor causes a current to flow in the charging direction to the terminal unit power storage device, For each intermediate unit power storage device other than the unit energy storage device is configured to connect one end of the reactor to either one of both ends of the connection point of the intermediate unit power storage device,
The electromagnetic energy stored in the reactor is opened by turning on a switching circuit connected to a unit power storage device group that does not include the intermediate unit power storage device of the two unit power storage device groups divided from the connection and then opening the switching circuit. Performs a first operation of flowing a current in a charging direction to a unit power storage device group including an intermediate unit power storage device, and then performs the first operation among connection points at both ends of the intermediate unit power storage device.
One end side of the reactor is connected to a connection point on the side opposite to the operation, and a switching circuit connected to a unit power storage device group that does not include the intermediate unit power storage device of the two unit power storage device groups divided from the connection is formed. The switch element and the pair are configured to perform a second operation of flowing a current in a charging direction to a unit power storage device group including an intermediate unit power storage device by opening the switch after being turned on and by opening the switch by the electromagnetic energy stored in the reactor. And a control unit that controls the switching circuit of the above. 2. A charge / discharge control device for a power storage device, wherein three or more unit power storage devices are connected in series between positive and negative output terminals for charging and discharging, wherein a reactor and one end side of the reactor are connected to each of the unit power storage devices. A switch element that can be selectively connected to each connection point between, a pair of switching circuits connected between the other end of the reactor and each of the positive and negative terminals, and a position at both ends of the power storage device. For each terminal unit power storage device to be connected, while connecting one end side of the reactor to the connection point with another unit power storage device adjacent to it, after turning on the switching circuit connected to the terminal unit power storage device By opening, the electromagnetic energy stored in the reactor causes a current to flow in the charging direction to the unit power storage device excluding the terminal unit power storage device, For each intermediate unit power storage device other than the unit energy storage device is configured to connect one end of the reactor to either one of both ends of the connection point of the intermediate unit power storage device,
By turning on the switching circuit connected to the unit power storage device group including the intermediate unit power storage device of the two unit power storage device groups divided from the connection and then opening the switching circuit,
The first operation of flowing a current in the charging direction to the unit power storage device group not including the intermediate unit power storage device by the electromagnetic energy stored in the reactor is performed, and then the first operation among the connection points at both ends of the intermediate unit power storage device is performed. 1
One end side of the reactor is connected to the connection point on the opposite side to the operation, and a switching circuit connected to a unit power storage device group including the intermediate unit power storage device of the two unit power storage device groups divided from the connection is turned on. The switch element and the pair of members are opened so as to perform a second operation of flowing a current in the charging direction to the unit power storage device group not including the intermediate unit power storage device by the electromagnetic energy stored in the reactor by opening it after the operation. And a control unit that controls the switching circuit of the above. 3. The control means controls the unit power storage device having the minimum voltage, provided that the difference between the maximum voltage and the minimum voltage of the voltages of the unit power storage devices is equal to or greater than a predetermined value. The charge / discharge control device for a power storage device according to claim 1, wherein the charge / discharge control device operates. 4. The control means controls the unit power storage device exhibiting the maximum voltage on condition that the difference between the maximum voltage and the minimum voltage among the voltages of the respective unit power storage devices is equal to or more than a predetermined value. The charge / discharge control device for a power storage device according to claim 2, wherein the charge / discharge control device operates. 5. The minimum value of the voltage of each of the unit power storage devices and the average value of the voltage of each of the unit power storage devices is equal to or more than a predetermined value, The charge / discharge control device for a power storage device according to claim 1, wherein the control operation is performed for a unit power storage device indicating a voltage. 6. The control means is conditioned on the condition that the difference between the maximum voltage of the voltages of the unit power storage devices and the average value of the voltages of the unit power storage devices is equal to or more than a predetermined value. The charge / discharge control device for a power storage device according to claim 2, wherein the control operation is performed for a unit power storage device indicating a voltage.