JP3458740B2 - Battery charging and discharging devices - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembled battery charging device and a discharging device, and more particularly to charging an assembled battery without causing overcharging or overdischarging due to variations in capacity of individual cells constituting the assembled battery. The present invention also relates to a charging device and a discharging device that can efficiently perform discharging.

[0002]

2. Description of the Related Art In recent years, the development of electric vehicles has become enthusiastic, and as a secondary battery used for this,
Small-sized and large-capacity lithium-ion batteries are receiving attention. When such a secondary battery is used as a power source for an electric vehicle or the like, a desired voltage value is usually obtained by connecting a plurality of single cells in series to form an assembled battery. But,
Lithium-ion batteries, etc. are likely to have variations in capacity due to manufacturing history and subsequent usage history, etc. If the battery pack is charged or discharged as a unit, overcharging or overdischarging of small-capacity cells will cause performance deterioration. There was a problem.

Therefore, for example, in Japanese Unexamined Patent Publication No. 5-64377, the charging state is detected from the terminal voltage of each unit cell, and when at least one of the unit cells is fully charged, the assembled battery is charged. A charging device that can be stopped has been proposed. However, this charging device has a problem in that the charging of the entire battery pack is limited by the unit cells having a small capacity, so that the other unit cells having a large capacity are not sufficiently charged and the charging ability is not fully utilized. .

Therefore, for example, in the charging device described in Japanese Patent Laid-Open No. 8-213055, a shunt circuit is provided in parallel with each unit cell, and when one of the unit cells is fully charged, the shunt circuit is used so as to bypass the unit. The charging current is passed so that other cells can continue to be charged. However, this charging device has a problem that the charging energy is unnecessarily consumed by the resistor provided in the shunt circuit for bypassing a part of the charging current.

On the other hand, in Japanese Patent Laid-Open No. 7-335266, a supplemental charging battery is connected to each unit cell via a switching circuit, and when the unit cell is overcharged, the unit cell is supplementally charged. A charging device has been proposed in which a battery is connected to prevent overcharging. However, in this charging device, since a supplementary charging battery is provided for each unit cell, there is a problem in that an increase in the size of the entire device and an increase in cost cannot be avoided.

When the battery pack is discharged, the unit cell having the smallest capacity may be over-discharged as described above. However, in the conventional charging devices described in the above publications,
There is no suggestion of a solution to this.

[0007]

SUMMARY OF THE INVENTION Therefore, the present invention is intended to solve the above-mentioned problems, in which wasteful consumption of charging energy can be avoided, and the size and cost of the battery are small. An object of the present invention is to provide a battery pack charging device and a battery pack discharging device that prevent not only overcharging but also overdischarging, and that enable efficient charging and discharging of the battery pack.

[0008]

In order to achieve the above-mentioned object, the charging device of the present invention has a battery pack (C
B) a plurality of cells (1A, 1B, 1C),
Auxiliary charger / discharger (2), charge state detection means (3A, 3B, 3C) for detecting the charge state of each unit cell, and assembled battery (C
When a cell (1A) that is about to be overcharged occurs during charging of B), the first cell (1A) that is about to be overcharged and one or more appropriate number of cells (1B) adjacent to this cell are The first series battery group (1A, 1B) selected as the series battery group
After connecting in parallel to the auxiliary charger / discharger (2), the unit cell (1C) having the lowest charge level at this time is selected from the unit cells, or the unit cell including the unit cell having the lowest charge level is selected. The number of adjacent cells that are less than the series battery group
Of the unit cell (1C) having the lowest charging level or the second group of battery cells connected in parallel to the auxiliary charger / discharger (2), and repeats the switching operation during charging. ) And.

In the battery charger having the above structure, when charging the assembled battery, the unit cell having the smallest capacity among the unit cells having the different capacities first comes close to overcharge. Therefore,
When the first series battery group including the unit cells that were close to overcharging was connected to the auxiliary charger / discharger, current was supplied from the first series battery group to the auxiliary charger / discharger and it became close to overcharging. The voltage of the unit cell drops, and the state of overcharge is resolved. After that, when a number of second series battery groups including the unit cell having the lowest charge level at this point and smaller in number than the first series battery group are connected to the auxiliary charger / discharger, the voltage of the auxiliary charger / discharger changes. Since the voltage is higher than the voltage of the second series battery group, the current of the auxiliary charger / discharger is efficiently discharged and supplied to the second series battery group.
The series battery group of is charged. When another unit cell is about to be overcharged, a similar operation is performed between the new first series battery group including the other unit cell and the auxiliary charger / discharger, so that the state of overcharge is one after another. At the same time, the auxiliary charger / discharger charges the second series battery group to make the state of charge of each unit cell uniform. In this state, charging of the assembled battery proceeds, and when all the unit cells are fully charged, the charging operation of the device ends.

As described above, according to the charging device of the present invention, the current is supplied from the first series battery group including the unit cells that are about to be overcharged to the auxiliary charging / discharging device to eliminate the state of being overcharged. At the same time, a current is supplied from the auxiliary charger / discharger to the second series battery group including the unit cell having the lowest charge level to charge the same, so charging is performed so as to bypass the unit cell that is about to be overcharged. It is possible to avoid wasteful consumption of charging energy as compared with a conventional device in which a current is supplied to a shunt circuit. Moreover, since the auxiliary charger / discharger is switched and used for the first series battery group including the single battery which is about to be overcharged,
Compared with the conventional device in which each unit cell is provided with a supplementary rechargeable battery, the size of the entire device is reduced and the cost is reduced. Furthermore, since the capacity of each cell is fully charged, a cell with a large capacity will not be uncharged,
No waste of battery capacity. Further, since it is not necessary to reduce the charging current to the assembled battery, the charging time of the assembled battery as a whole can be shortened. Further, according to the present invention, the voltage of the auxiliary charger / discharger can be increased significantly compared to the second series battery group charged by the auxiliary charger / discharger, so that the amount of energy transfer becomes large, and the device can be correspondingly increased. It is possible to downsize, reduce time, and improve energy efficiency. Here, the charge level means the ratio of the discharge capacity that can be taken out to the remaining capacity (SOC) of the battery or the rated capacity of the battery.

The discharge device of the present invention comprises a plurality of cells (1A, 1B, 1) which are connected in series to form an assembled battery (CB).
C), an auxiliary charging / discharging device (2), a discharge state detecting means (3A, 3B, 3C) for detecting the discharge state of each cell, and a cell (1A) which is about to be over-discharged during discharging of the assembled battery. Occurs, the single cell (1B) having the highest charging level at this point and an appropriate number of single cells (1C) adjacent thereto are selected as the third series battery group, and the third series battery is selected. After connecting the series battery group (1B, 1C) to the auxiliary charger / discharger (2) in parallel, the unit cell (1A) which is close to over-discharging is selected from the unit cells, or a unit cell which is close to over-discharge is selected. An appropriate number of adjacent cells, which are smaller in number than the series battery group of No. 3, are selected as the fourth series battery group, and the single battery (1A) or the fourth series battery group that is about to be overdischarged is an auxiliary charger / discharger. The discharge switching connection means (5) for repeating the switching operation connected in parallel with (2) is provided.

In the discharge device having the above-mentioned structure, when the assembled battery is discharged, the unit cell having the smallest capacity among the unit cells having the different capacities first comes close to over-discharge. Therefore,
At this point, when the third series battery group including the unit cell having the highest charge level is connected to the auxiliary charger / discharger, current is supplied from the third series battery group to the auxiliary charger / discharger.
After that, when the fourth series battery group including the cells that are about to be over-discharged is connected to the auxiliary charger / discharger, the voltage of the auxiliary charger / discharger is higher than the voltage of the fourth series battery group. The electric current of the electric appliance is efficiently supplied to the fourth series battery group, and the state of the unit cell near the overdischarge is eliminated. When another unit cell is about to be over-discharged, the same operation is performed between the new fourth series battery group including the other unit cell and the auxiliary charger / discharger, and the over-discharge state is successively set. At the same time, the discharge is discharged from the third series battery group to the auxiliary charger / discharger, and the discharge state of each unit cell is made uniform. In this state, the discharge of the assembled battery progresses, and when the discharge of all the unit cells is completed, the discharging operation of the device ends.

As described above, according to the discharging device of the present invention, the auxiliary charging / discharging device is switched and used for the fourth series battery group including the cells which are about to be over-discharged. And cost reduction is also realized. In addition, since each unit cell is discharged to the full capacity, a unit cell having a large capacity is not undischarged, and the battery capacity is not wasted. Further, according to the present invention, the voltage of the auxiliary charger / discharger can be increased significantly compared to that of the fourth series battery group charged by the auxiliary charger / discharger, so that the energy transfer amount becomes large, and the device is correspondingly increased. Smaller size, shorter time,
It is possible to improve energy efficiency.

The charging device and the discharging device described above can be integrated into a charging / discharging device having the following configuration. According to this, it is possible to obtain both the action and effect obtained by the charging device and the discharging device already described. You can That is, the charging / discharging device shows a plurality of cells (1A, 1B, 1C) connected in series to form an assembled battery (CB), an auxiliary charger / discharger (2), and a charging / discharging state of each cell. The charging / discharging state detecting means (3A, 3B, 3C) for detecting, and when a battery (1A) near overcharge occurs during charging of the assembled battery (CB), the battery (1A) near this overcharge and this Select one or more appropriate number of unit cells (1B) adjacent to each other as the first series battery group, and connect the first series battery group (1A, 1B) in parallel with the auxiliary charger / discharger (2). After connecting, the cell (1C) having the lowest charge level at this point is selected from the cells, or the number of adjacent cells including the cell having the lowest charge level is smaller than that of the first series battery group. Select the batteries as the second series battery group, and select the battery (1
C) or a charge-time switching connection means (5) that repeats the switching operation of connecting the second series battery group to the auxiliary charger / discharger (2) in parallel, and a single battery (1) that is about to be over-discharged during discharging of the assembled battery.
When A) occurs, the unit cell (1B) having the highest charging level at this point and a proper number of unit cells (1C) adjacent thereto are selected as the third series battery group, and After connecting the series battery groups (1B, 1C) of No. 3 in parallel to the auxiliary charger / discharger (2), the single cell (1A) that is near overdischarge is selected from the single cells, or the above single cell that is near overdischarge. A proper number of adjacent cells, which is smaller in number than the third series battery group, including the above is selected as the fourth series battery group to assist the near-overdischarge single cell (1A) to the fourth series battery group. The charging / discharging device (2) is connected in parallel with the discharging switching connection means (5) for repeating the switching operation.

A capacitor or a secondary battery can be used as the auxiliary charger / discharger. Since the electric capacity of the secondary battery is significantly larger than that of the capacitor, in this case, the charging / discharging device of the assembled battery can have the following configuration. That is, a plurality of unit cells (1A, 1B, 1C) that are connected in series to form an assembled battery (CB), auxiliary chargers / dischargers (7A to 7B), and charge / discharge states of each unit cell (1A to 1C). Charging / discharging state detecting means (3A, 3B, 3C) for detecting
When a battery that is about to be overcharged occurs during charging of the assembled battery (CB), the unit cell (1A) that is about to be overcharged and one or more appropriate number of unit batteries (1B) adjacent to this battery will be A charging-time switching connection means (5) for selecting and connecting the fifth series battery group (1A, 1B) as a series battery group (1A, 1B) to an auxiliary charger / discharger (7A to 7B). Battery (C
When a cell near the over-discharge occurs during the discharge of B), the cell (1A) close to the over-discharge is selected or less than the fifth series battery group including the cell near the over-discharge. A number of adjacent cells are selected as the sixth series battery group, and the above single cell (1A) or the sixth series battery group, which is about to be overdischarged, is switched and connected to the auxiliary charger / discharger (7A or 7B). And a time switching connection means (5). In this case, the rated voltage of the auxiliary charger / discharger is lower than the rated voltage of the fifth series battery group, and is higher than the rated voltage of the single cell or the sixth series battery group that is about to be overdischarged.

In the charging / discharging device having such a structure, when the assembled battery is charged, the unit cell having the smallest capacity among the unit cells having the different capacities is first overcharged. Therefore, the fifth including the single battery which is about to be overcharged
When the series battery group of is connected to the auxiliary charger / discharger, a voltage is supplied to the auxiliary charger / discharger to reduce the voltage of the unit cell that is near overcharge, and the state of near overcharge is eliminated. Subsequently, when another unit cell is near to overcharge, a new fifth series battery group including the other unit cell is sequentially switched and connected to the auxiliary charger / discharger, and the state of near overcharge is eliminated one after another. In this state, charging of the assembled battery proceeds, and when all the unit cells are fully charged, the charging ends.

When the assembled battery is discharged, the unit cell having the smallest capacity among the unit cells having variations in capacity is first approaching overdischarge. Therefore, when an auxiliary charging / discharging device is connected to the sixth series battery group including the unit battery which is about to be over-discharged, a current is supplied from the auxiliary charging / discharging device to the unit battery which is about to be over-discharged, so that the unit cell The voltage rises, and the over discharge condition is eliminated. Then, when another unit cell is about to be over-discharged, the auxiliary charger / discharger is sequentially switched and connected to the new sixth series battery group including the unit cell, and the state of the over-discharge unit is eliminated one after another. In this state, the battery pack is discharged, and when all the unit cells are completely discharged, the discharge is finished.

As the secondary battery of the auxiliary charger / discharger, a lead battery for an auxiliary machine of a vehicle or the like can be used. In this case,
Partition the secondary battery into an appropriate number of battery cells (7A, 7B),
The rated voltage of each battery cell is set to be lower than the rated voltage of the fifth series battery group and larger than the rated voltage of the unit cell to the sixth series battery group, and the fifth series battery group to the sixth series battery group. Each battery cell is appropriately selected and connected to the series battery group of.

Further, when the assembled battery is discharged, the sixth series battery group can be charged with a suitable number of battery cells (7A, 7B) connected in series. In this case, the series-connected batteries are charged. The rated voltage of the entire cell is set to be higher than the rated voltage of the unit cell or the sixth series battery group.

In the charging device or the discharging device described above, the switching connection means (5) during charging or the switching connection means (5) during discharging.
It is possible to further provide a short-circuit preventing means (8) for preventing the positive electrode side and the negative electrode side of each of the unit cells (1A to 1D) from being directly connected during the switching operation of. As a result, it is possible to prevent the charge-time switching connecting means or the discharge-time switching connecting means from being damaged by a short circuit of the unit cell.

According to the present invention, when the charge switching connection means (5) or the discharge switching connection means (5) is switched, only a predetermined number or less of the unit cells (1A to 1D) are connected to the auxiliary charger / discharger (2). ), Connection restriction means (8) for restricting the connection can be provided. As a result, it is possible to prevent overvoltage from being applied to the auxiliary charger / discharger.

Further, in the present invention, when there is a sufficient voltage difference between the unit cell which is about to be overcharged at the time of charging operation and the unit cell which has the lowest charge level at this point, the charging switching connection means is It suffices to connect the unit cells to the auxiliary charger / discharger in parallel and then connect the unit cells having the lowest charge level to the auxiliary charger / discharger in parallel. Further, in the present invention, when there is a sufficient voltage difference between the cell that is about to be over-discharged at the time of discharge operation and the cell that has the highest charge level at this time, the charging switching connection means has the highest charge level. It suffices if the unit cells are connected in parallel to the auxiliary charger / discharger, and then the unit cells that are about to be over-discharged are connected in parallel to the auxiliary charger / discharger.

Further, the operation of equalizing the charged state or the discharged state of the unit cells performed by the charging device or the discharging device is as follows.
It is not necessary to perform the operation only after a single cell near overcharge or overdischarge is generated, and the homogenizing operation may be performed during the whole process during charging or discharging. The structure of the charging device or discharging device in this case is as follows.

That is, the battery charger for the assembled battery comprises a plurality of cells connected in series to form an assembled battery, an auxiliary charger / discharger, and a charge level detecting means for detecting the charge level of each battery. During charging of the battery, a cell having the highest charging level, or an appropriate number of one or more cells including the cell having the highest charging level and adjacent thereto is selected as the first series battery group, After connecting the unit cell having the highest charge level or the first series battery group in parallel to the auxiliary charger / discharger, the unit cell having the lowest charge level is selected at this point, or the unit having the lowest charge level is selected. The number of adjacent cells including the cells, which is smaller than that of the first series battery group, is selected as the second series battery group, and the unit cell having the lowest charge level or the second series battery group is selected as the above. In parallel with the auxiliary charger / discharger It has and a charging time of switching and connecting means to repeat the switching operation to continue.

Further, the assembled battery discharging device includes a plurality of unit cells connected in series to form an assembled battery, an auxiliary charger / discharger, a charge level detecting means for detecting a charge level of each unit battery, and a set. During discharging of the battery, a cell having the highest charge level, or an appropriate number of one or more cells including the cell having the highest charge level and adjacent thereto is selected as the third series battery group, After connecting the unit cell having the highest charge level or the third series battery group in parallel to the auxiliary charger / discharger, at this time, the unit cell having the lowest charge level is selected or the unit having the lowest charge level is selected. The number of adjacent cells including the cells, which is smaller than that of the third series battery group, is selected as the fourth series battery group, and the unit cell having the lowest charge level or the fourth series battery group is selected as the above. Connected in parallel with auxiliary charger / discharger It is provided with a discharge time of switching and connecting means to repeat that switching operation.

The reference numerals in the parentheses indicate the correspondence with specific means described in the embodiments described later.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows a schematic overall structure of a charging / discharging device. The charging / discharging device has an assembled battery CB in which a large number of unit cells 1A, 1B, 1C, ..., 1N such as lithium-ion batteries are connected in series, and a main switch 41 and a current sensor 42 are connected to a charging / discharging line L extending from the assembled battery CB. Is provided. When charging the assembled battery CB, current is supplied from the charging power source 81 to the charge / discharge line L, while the assembled battery C is charged.
When B is discharged, current is supplied from the charge / discharge line L to the load 82. The operation of the charging power source 81 is controlled by a signal from the control circuit 4 having a built-in CPU. Main switch 4
1 is opened and closed by a signal from the control circuit 4,
Further, the control circuit 4 takes in the detection signal of the current sensor 42 and determines whether or not the battery pack CB is being discharged.

Voltmeters 3A, 3 are provided for each of the cells 1A-1N.
, 3N are connected in parallel, and each voltmeter 3A-
The voltage signal from 3N is input to the control circuit 4. In a lithium-ion battery or the like, the charge level and the battery voltage are in a substantially proportional relationship, so the control circuit 4 can easily and accurately know the charge state or discharge state of each of the cells 1A to 1N by the voltage signal. Of course, it is possible to know the charge / discharge state by means other than the voltmeter. A capacitor 2 as an auxiliary charging / discharging device is provided, and a switching circuit 5 serving as a switching connection means during charging operation and discharging operation is provided between the capacitor 2 and the unit cells 1A to 1N.
The switching circuit 5 is switched in response to a signal from the control circuit 4 as will be described later, and selects a single battery cell or a series battery group including an appropriate number of adjacent battery cells to switch and connect to the capacitor 2. The capacity of the capacitor is about several thousand to 10,000 μF.

FIG. 2 shows the switching circuit 5 in more detail for the cells 1A to 1C. The switching circuit 5 includes a pair of FET switches 5 that connect the positive electrodes of the cells 1A to 1C and the positive electrode of the capacitor 2.
1A, 52A and 53A, 54A and 55A, 56
A and a pair of FET switches 51B, 52B and 5 connecting the negative electrodes of the cells 1A to 1C and the negative electrode of the capacitor 2.
3B, 54B and 55B, 56B. The pair of FET switches 51A to 56B are connected in series with each other.
The diode elements 57 and 58 are formed in the interiors of the terminals 56 to 56B so as to connect the terminals to each other.
8 are connected to each other on the anode side. In addition, FET
The switches 51A to 56B are activated by a signal from the control circuit 4. The signal of the current sensor 42 is actually input to the control circuit 4 after being amplified by the amplifier 43 as shown in the figure.

The operation of the charging / discharging device having such a configuration will be described below with reference to the flowcharts of FIGS. 3 and 4 showing the processing procedure of the CPU in the control circuit 4. FIG. 3 shows the charging operation. In step 101, the main switch 41 is closed and the charging power source 81 is instructed to start charging to charge the assembled battery CB. As charging progresses, the unit cell 1A ~
Of 1N, the one with the smallest capacity is about to be overcharged.
Whether or not overcharge is approaching is detected by the voltage signal from the voltmeters 3A to 3N. When it is confirmed in step 102 that any of the unit cells 1A to 1N is about to be overcharged, step 1
In 03, the unit cell that was almost overcharged and the adjacent 1
An appropriate number (for example, one) or more of unit cells is selected as the first series battery group, and this first series battery group is connected in parallel to the capacitor 2 by the switching circuit 5 (step 104). After a certain period of time (step 10
5) In step 106, the unit cells having the lowest charge level among the unit cells 1A to 1N, or the unit cells having the lowest charge level and including a smaller number of adjacent unit cells than the first series battery group are connected. The second series battery group is selected as the second series battery group, and the single battery or the second series battery group having the lowest charge level is connected in parallel to the capacitor 2 by the switching circuit 5 for a certain time (steps 107 and 108). Step 10
At 9, it is confirmed whether all the single cells are fully charged.

For example, in FIG. 2, it is assumed that the unit cell 1A is about to be overcharged, the unit cell 1C has the lowest charge level, and the unit cell 1B has a charge level intermediate between the two. The control circuit 4 selects the unit cell 1A and the unit cell 1B adjacent thereto as the first series battery group, and activates the FET switches 51A and 54B. This makes the first
From the series battery group 1A, 1B of FIG. 1, the diode element 58 of the FET switch 52A, the capacitor 2, the FET switch 53
A current flows to the diode element 57 of B, the voltage of the unit cell 1A drops, and the capacitor 2 is charged.
After the elapse of a certain time t1, the control circuit 4 selects the cell 1C having the lowest charge level, and the FET switch 51
FET switches 56A and 55B are turned on instead of A and 54B. As a result, from the capacitor 2 to the diode element 57 of the FET switch 55A, the unit cell 1C, the FE
A current flows to the diode element 58 of the T switch 56B, and the single battery 1C is charged. Since the voltage of the capacitor 2 at this time is almost twice the voltage of the unit cell 1C, efficient and reliable charging can be quickly performed. After a certain time t2 has passed, the FET switches 56A and 55B are turned off.
The constant times t1 and t2 are the first series battery group 1
Sufficient time is required for A and 1B and the capacitor 2 or between the unit cell 1C and the capacitor 2 to reach an equilibrium state and no current flows. Therefore, it may be possible to detect that the current actually stops flowing and move to the next operation.

The above operation, that is, step 10 in FIG.
The operations of 2 to step 109 are repeated, for example, at 5 Hz, and when another unit cell is about to be overcharged, the other unit cell and the unit cell adjacent thereto are selected as a new first series battery group. The same operation is repeated via the capacitor 2 between the new first series battery group and the unit cell having the lowest charge level at this time, or the second series battery group including the single battery group. In step 109, all cells 1A to 1N
When it is confirmed that the battery is fully charged, step 110
To stop the operation of the charging power source 81, and the main switch 41
open.

Such charging operation will be described with reference to FIG. The figure shows an example in which eight unit cells 1A to 1H are provided.
A, 1D, 1F, 1H are lower than the average charge level Av, and the unit cells 1B, 1C, 1E, 1G are the average charge level A.
The state is above v. Now, single cell 1
It is assumed that E is almost overcharged. The control circuit 4 selects the unit cell 1E and the unit cell 1F adjacent thereto as the first series battery group, and charges the unit cell 1D having the lowest charging level via the capacitor 2. The unit cell 1D is almost 2 of this
The double voltage Vc is efficiently charged through the capacitor 2. In the figure, W indicates a voltage that is approximately proportional to the charge capacity from each of the cells 1E and 1F. When the state of the overcharge of the unit cell 1E is resolved, and then the unit cell 1B is about to be overcharged,
The control circuit 4 then selects the unit cell 1B and the unit cell 1C adjacent thereto as a new first series battery group, connects this to the capacitor 2, and eliminates the state of the overcharge of the unit cell 1B. . If the charging level of the unit cell 1F is the lowest at this point, the control circuit 4 connects the capacitor 2 to the unit cell 1F this time and charges it. The unit cell 1F is efficiently charged with a voltage Vc that is almost twice this voltage. By repeating such an operation, the charging level of all the unit cells 1A to 1H is made uniform without overcharging, and in this state, each unit cell 1A to 1H is fully charged by being fully charged. It becomes a state.

On the other hand, during discharge operation by the charging / discharging device,
In step 201 of FIG. 4, the main switch 41 is closed and current is supplied from the assembled battery CB to the load 82. As the discharge progresses, the unit cells 1A to 1N with the smallest capacity reach the lower limit voltage and are approaching overdischarge. Therefore, steps 202 and 2
In 03, after confirming that the discharge to the load 82 is stopped by the detection signal of the current sensor 42, the unit cells 1A to 1N
Check if is about to over discharge. Whether or not the over-discharge is approaching is detected by the voltage signal from the voltmeters 3A to 3N. Step two
When it is confirmed in 03 that any one of the unit cells 1A to 1N is about to be over-discharged, in Step 204, the unit cell having the highest charge level at this time and one or more appropriate number (for example, one unit) adjacent to the unit cell. Cell is selected as the third series battery group, and this third series battery group is connected in parallel to the capacitor 2 by the switching circuit 5 (step 20).
5). Then, after a certain time has passed (step 206),
In step 207, among the unit cells 1A to 1N, the unit cell that is about to be over-discharged or the unit cell that is about to be over-discharged is included in the third unit
The number of adjacent cells which is smaller than that of the series battery group is selected as the fourth series battery group, and the single cell or the fourth series battery group which is about to be over-discharged is paralleled to the capacitor 2 by the switching circuit 5 for a certain time. Connect (steps 208, 2)
09). At step 210, it is confirmed whether or not all the unit cells are completely discharged.

For example, in FIG. 2, it is assumed that the unit cell 1A is about to be over-discharged, the charging level of the unit cell 1B is highest at this time, and the charging level of the unit cell 1C is between the two. The control circuit 4 selects the unit cell 1B and the unit cell 1C adjacent to the unit cell 1B as the third series battery group, and activates the FET switches 53A and 56B. This makes the third
From the series battery group 1B, 1C of the FET switch 54A to the diode element 58, the capacitor 2, the FET switch 55
The current flows to the diode element 57 of B, and the capacitor 2
Is charged. After the elapse of a certain time t3, the control circuit 4 selects 1A which is near over discharge this time, and the FET switch 53
FET switches 52A and 51B are turned on instead of A and 56B. As a result, from the capacitor 2 to the diode element 57 of the FET switch 51A, the unit cell 1A, the FE
A current flows to the diode element 58 of the T switch 52B to charge the single cell 1A, and its voltage rises. Since the voltage of the capacitor 2 at this time is almost twice the voltage of the unit cell 1A, efficient and reliable charging can be quickly performed. After a lapse of a certain time t4, the FET switches 52A and 51B
Is turned off. The constant time t3, t4 is the third
It is set to a time sufficient for the series battery groups 1B and 1C and the capacitor 2 or the unit cells 1A and the capacitor 2 to reach an equilibrium state and no current flows. Therefore, it may be possible to detect that the current actually stops flowing and move to the next operation.

The above operation, that is, step 20 in FIG.
The operation of 2 to step 210 is repeated, for example, at 5 Hz, and when another unit cell is overdischarged, the unit cell is connected between the other unit cell or the fourth series battery group including the other unit cell and the third series battery group. The same operation is repeated via the capacitor 2. When it is confirmed in step 210 that the discharge of all the cells 1A to 1N is completed, the main switch 41 is opened in step 211 and the discharge operation is ended. In addition,
It is better to confirm the discharge state of the unit cells 1A to 1N only when the discharge to the load 82 is stopped as in the present embodiment. The reason is that the terminal voltage of the unit cells 1A to 1N fluctuates when the discharge current is flowing, and the discharge state may not be accurately determined. In addition to the current sensor 42, whether or not the discharge is stopped can be detected from the voltage change pattern of the unit cells 1A to 1N.

As a result of such discharge operation, the discharge levels of all the unit cells 1A to 1H are made uniform without causing overdischarge, and the discharge is completed almost at the same time. Therefore,
Over-discharging of the unit cells 1A to 1H can be avoided, and no residual charge is generated in each unit cell at the end of the discharge operation. Therefore, deterioration of the battery due to recharging with remaining charge can be avoided.

In the example shown in FIG. 2, when the charging level of the unit cell 1B is the lowest at the time of charging, the unit cells 1A and 1B are selected as the first series battery group, and the first series battery is selected. The series battery groups 1A and 1B are connected to the capacitor 2 to be charged, and then the capacitor 2 is connected to the unit battery 1B to be charged. In this case, the charge level of the unit cell 1B temporarily drops when the capacitor 2 is charged, but the charge level is recovered more than before by the subsequent charge from the capacitor 2. When the single cell 1B is about to be over-discharged at the time of discharging, the single cells 1B and 1C are selected as the third series battery group, and the third series battery is selected.
The series battery groups 1B and 1C are connected to the capacitor 2 for charging, and then the capacitor 2 is connected to the unit cell 1B for charging. In this case as well, the charge level of the unit cell 1B temporarily decreases, but the charge level recovers more than before by the charging from the capacitor 2.

(Second Embodiment) As an auxiliary charger / discharger, a secondary battery can be used instead of the capacitor 2 of the first embodiment. As this secondary battery, the same lithium-ion battery as a single battery can be used, but it is resistant to overcharge,
Lead batteries or nickel-cadmium batteries are preferably used because of their excellent short-term current input / output characteristics. In particular, the lead battery is often used as an auxiliary battery for vehicles and the like, and thus can be used or used as an auxiliary charger / discharger. An example of the circuit in this case is shown in FIG. The lead battery has a different voltage from the lithium-ion battery, so an appropriate number (3 in the figure)
Are connected in series to form battery modules 7A and 7B. The voltages of the battery modules 7A and 7B are the same as those of the first series battery groups 1A and 1B when charging the assembled battery described in the first embodiment and the third series battery groups 1B and 1C when discharging the assembled battery (see FIG. Two
In each of the examples described in 1., the voltage is lower than the voltage in which two assembled batteries are connected in series), and the second series battery group when charging the assembled battery and the fourth series when discharging the assembled battery described in the first embodiment. The voltage is set to be higher than the voltage of the battery group (in the example described with reference to FIG. 2, each is the voltage of the single cell 1A or 1C). For example, if three lead batteries having a rated voltage of about 2V are used as the battery modules 7A and 7B, the battery modules 7A and 7B
The rated voltage of B is higher than that of one unit cell using a 3.6V lithium-ion battery and lower than that of a series battery group including two unit cells.

In this embodiment, the switching circuit 5 is the first
In addition to the configuration of the embodiment, FET switches 59A, 6 connected in series with each other between the positive electrodes of the battery modules 7A, 7B and the FET switches 52A, 54A, 56A.
0A, 61A and 62A are provided, and the negative electrodes of the battery modules 7A and 7B and the FET switches 52B and 54B,
FET switches 59B, 60B and 61B, 62B connected in series with each other are provided between the switch 56B and 56B.
Diode elements 63 and 64 are formed inside the FET switches 59A to 62B so as to connect their terminals, and the diode elements 63 and 64 are connected to each other on the anode side. The FET switches 59A to 62B are also activated by the signal from the control circuit 4.

During the charging operation of the charging / discharging device, the unit cell 1A is about to be overcharged. At this time, the unit cell 1C has the lowest charge level, and the unit cell 1B has the charge level intermediate between the two. . The control circuit 4 selects the unit cell 1A and the unit cell 1B adjacent thereto as the first series battery group,
The FET switches 51A, 60A, 54B and 59B are turned on. Thereby, the first series battery group 1A, 1B
To FET element 52 of FET switch 52A, FE
The diode element 63 of the T switch 59A, the battery module 7A, the diode element 64 of the FET switch 60B,
A current flows to the diode element 57 of the FET switch 53B, the voltage of the unit cell 1A drops, and the battery module 7A is charged. First series battery group 1 at this time
Since the voltages of A and 1B are higher than the voltage of the battery module 7A, efficient and reliable charging is performed. Fixed time t5
After a lapse of time, the control circuit 4 now selects the unit cell 1C having the lowest charge level, and the FET switches 51A, 60A, 5
FET switches 59A, 56A, instead of 4B, 59B
55B and 60B are activated. Accordingly, from the battery module 7A to the diode element 64 of the FET switch 60A, the diode element 57 of the FET switch 55A,
Single cell 1C, FET switch 56B diode element 5
8. A current flows to the diode element 63 of the FET switch 59B, and the unit cell 1C is charged. Since the voltage of the battery module 7A at this time is higher than the voltage of the unit cell 1C, efficient and reliable charging is performed. After a lapse of a certain time t6, the FET switches 59A, 56A, 55B, 6
0B is made non-conductive.

The above operation is repeated at a constant cycle, and when another unit cell is overcharged, the other unit cell and the unit cell adjacent thereto are selected as a new first series battery group. The same operation is repeated between the new first series battery group and the unit cell having the lowest charge level at this time via the battery module 7A. As a result of such charging operation,
The charging level of each of the unit cells 1A to 1C at the time of charging is made uniform, and the charging is completed at substantially the same time in all the unit cells 1A to 1C. Therefore, since each unit cell is not overcharged during charging, deterioration of the battery can be avoided.

During the discharge operation of the charging / discharging device, the unit cell 1A is about to be over-discharged. At this time, the unit cell 1B has the highest charge level, and the unit cell 1C has the charge level intermediate between the two. . The control circuit 4 selects the unit cell 1B and the unit cell 1C adjacent thereto as the third series battery group,
The FET switches 53A, 60A, 59B and 56B are turned on. Thereby, the third series battery group 1B, 1C
To FET element 54 of FET switch 54A, FE
The diode element 63 of the T switch 59A, the battery module 7A, the diode element 64 of the FET switch 60B,
A current flows to the diode element 57 of the FET switch 55B, and the battery module 7A is charged. Fixed time t7
After a lapse of time, the control circuit 4 now selects 1A which is about to be over-discharged, and replaces the FET switches 53A, 60A, 59B and 56B with FET switches 59A, 52A, 51B and 60B.
To activate. Thereby, the diode element 64 of the FET switch 60A and the FET from the battery module 7A
Diode element 57 of switch 51A, unit cells 1A, F
A current flows through the diode element 58 of the ET switch 52B and the diode element 63 of the FET switch 59B, and the unit cell 1A is charged. Since the voltage of the battery module 7A at this time is higher than the voltage of the battery module 7A, efficient and reliable charging is performed. After a predetermined time t8 has passed, the FET switches 52A and 51B are turned off.

The above operation is repeated at a constant cycle, and when another unit cell is overdischarged, the same operation is performed between the other unit cell and the third series battery group via the battery module 7A. Repeated. As a result of such discharge operation, the discharge levels of the individual cells 1A to 1C at the time of discharging are made uniform, and the discharge is completed at substantially the same time in all the single cells 1A to 1C. Therefore, over-discharging of each of the unit cells 1A to 1C is avoided, and no residual charge is generated in each unit cell at the end of the discharge operation. Therefore, battery deterioration due to recharging with remaining charge is also avoided. be able to.

During the charging operation or the discharging operation, FE is used instead of the FET switches 59A-60B.
By selectively conducting the T switches 61A to 62B, the first series battery group 1A, 1B and the unit cell 1C, or the third series battery group 1B, 1C and the unit cell 1A are charged via the battery module 7B, respectively. The battery modules 7A and 7B may be discharged, and by appropriately selecting and using the battery modules 7A and 7B, the charged state and the discharged state of the battery modules 7A and 7B can be made uniform.

When the voltage difference between the battery modules 7A or 7B and the cells 1A to 1C becomes small during charging or discharging of the assembled battery, only the FET switches 59A, 60A, 61B and 62B are operated. The battery modules 7A and 7B placed in series may be used to charge the unit cells 1A to 1C. Further, by appropriately operating the FET switches 51A to 56B, the battery modules 7A and 7B placed in series are used to operate the cells 1A and 1C, or the cells 1A and 1B placed in series.
It is also possible to charge 1B or 1C.

Further, when the secondary battery is used as the auxiliary charger / discharger as in the present embodiment, the times t5 and t6 when the assembled battery is charged or the time t when the assembled battery is discharged.
The periodic switching by 7 and t8 is not always necessary. For example, when all the cells 1A to 1C are fully charged and further charged from the charging power source 81 (FIG. 1) by regenerative power generation or the like, during this period, only the charging of the battery modules 7A and 7B is continued and the regenerative power generation is continued. 1A whose charge state has deteriorated when the assembled battery is discharged after charging by
It is also possible to continue discharging only the battery modules 7A and 7B for 1C. Even when the periodical switching is performed, the secondary battery has a much larger electric capacity than the capacitor, so that the time t5 to t8 is sufficiently longer than the time t1 to t4 in the first embodiment. By increasing the length, the number of times of switching can be reduced, and the loss in the switching circuit can be sufficiently reduced.

(Third Embodiment) The FET switches 51A and 52A in the switching circuit 5 in each of the above embodiments.
7 in place of the diode elements 65, 66, respectively, in the FET switches 51A, 52A.
Are newly connected in series, and these FET switches 51A, 5
2A and the diode elements 65 and 66 may be connected in parallel. The diode element 65 is connected to the internal diode 57 of the FET switch 51A on the anode side. Further, the diode element 66 is connected to the internal diode 58 of the FET switch 52A on the anode side. With such a configuration, elements having a low on-resistance such as Schottky diodes can be used as the diode elements 65 and 66, and the current loss in the switching circuit 5 can be further reduced. This circuit uses other FET switches 53A-56A, 5
1B to 56B, 59A to 62A, 59B to 62B can be directly applied.

(Fourth Embodiment) FIG. 8 shows a fourth embodiment of the present invention. In the first embodiment, the voltmeters 3A to 3C are provided in order to know the charging / discharging states of the individual cells 1A to 1C (see FIG. 2), whereas in the present embodiment, as shown in FIG. , A single voltmeter 3 in parallel with the capacitor 2
Only provided. The voltmeter 3 is connected in series with the normally open contact of the switch 31, while the capacitor 2 is connected with the normally closed contact of the switch 31. Other configurations are similar to those of the first embodiment.

In the present embodiment, for example, when measuring the voltage of the unit cell 1A, the switch 31 is operated to
The normally open contact is closed and the normally closed contact is opened. Then, the control circuit 4 activates only the FET switches 51A and 52B. Thereby, the positive electrode side of the unit cell 1A and the positive side of the voltmeter 3, and the negative side of the unit cell 1A and the voltmeter 3
The negative electrode side of is connected and the voltage of the unit cell 1A is measured.
When measuring the voltages of the unit cells 1B and 1C, the control circuit 4 sequentially turns on the FET switches 53A and 54B or the FET switches 55A and 56B. The switch 31 does not necessarily have to be provided.

According to this embodiment, it is not necessary to separately provide a voltmeter for each unit cell, so that the circuit is simplified,
Cost reduction can be achieved. Further, since the switching circuit for switching the capacitor is used, it is not necessary to newly provide a switch circuit for measuring the voltage.

(Fifth Embodiment) In FIG. 2 for explaining the first embodiment, when the FET switches 51A to 56B in the switching circuit 5 are switched by the control circuit 4, for example, the FET switch 51A and the FET switch are operated. If 54A operate | moves simultaneously, the positive electrode and negative electrode of the cell 1A will short-circuit. If you short-circuit a single cell, an excessive current will flow instantaneously, and there is a risk of abnormal heat generation in the single cell, leading to smoke and ignition, which must be avoided. Therefore, in the present embodiment, an example will be described in which a short-circuit prevention circuit that does not short-circuit a single cell when the FET switch of the switching circuit 5 operates is provided.

Here, the short circuit is prevented by preventing two or more switches from being simultaneously closed in the switch group connected to the same polarity side of the capacitor. When the closing operation signal of one switch is output, a guard is applied so that the closing operation signal of the switch on the lower potential side is not output. Of the switches that output the closing operation signal, only the switch on the highest potential side is enabled, and the closing operation of all the switches on the lower potential side is prohibited, so that two or more switches are simultaneously activated. Make sure it is not closed.

In FIG. 9, FET switches provided on the positive electrode side and the negative electrode side of each of the unit cells 1A to 1D are shown as single switches SW1P to SW4P and SW for easy understanding.
Typical examples are 1N to SW4N. For example, single cell 1A
When the positive side switch SW1P is closed, the single cells 1A to 1C are short-circuited regardless of which of the positive side switches SW2P to SW4P of the single cells 1B to 1D is closed. Similarly, when the negative electrode side switch SW1N of the unit cell 1A is closed, the negative electrode side switch SW2N of the unit cells 1B to 1D is closed.
The cells 1B to 1D are short-circuited regardless of which of the SW4N is closed. Therefore, in order to prevent such a short circuit, a short circuit prevention circuit 8 whose details will be described later is provided between the control circuit 4 and the switching circuit 5. Further, a voltmeter 9 is provided in parallel with the capacitor 2 so that each unit cell 1A
Although the voltage of ~ 1D is measured, in this case as well, the short-circuit prevention circuit 8 prevents the closing operation of the unnecessary switch as described later, thereby preventing the short-circuiting of the cells 1A-1D. It has become so.

FIG. 10 shows a circuit example of the short circuit prevention circuit 8.
In FIG. 10, signals B1P to B4P are signals output from the control circuit 4 and instructing the closing operation of the switches SW1P to SW4P, and signals B1N to B4N are switches SW1N to SW4N output from the control circuit 4, respectively. Is a signal for instructing the closing operation of the. In addition, the signals SW1P to SW4P are output from the short circuit prevention circuit 8 respectively, and the switches SW1
P-SW4P is a signal for closing operation, and signals SW1N-
SW4N is a signal output from the short-circuit prevention circuit 8 to close the switches SW1N to SW4N. The signal MES is a signal output from the control circuit 4 when measuring the voltage of the unit cells 1A to 1D.

The short-circuit prevention circuit 8 includes AND gates 81A to 81C whose one input is an inverting input and an AND gate 8
2A to 82D, OR gates 83A to 83D, AND gates 84A to 84D whose one input is an inverting input, and OR
It is composed of gates 85A to 85D, AND gates 86A to 86D whose one input is an inverting input, and three input AND gates 87A to 87D, and an arrow in the figure indicates that it is pulled up to a high level. ing.

In such a short-circuit prevention circuit 8, for example, when the signal B1P is input, the AND gate 82A is opened to output the signal SW1P and the switch SW1P is closed. At the same time, all the AND gates 82B to 82D are closed, and even if the signals B2P to B4P are input, the signals SW2P to SW4P are not output. In this way, the signals SW1P to SW4P
Only one signal is output at all times in the priority order, and the short circuits of the cells 1A to 1D due to the simultaneous operation of the switches SW1P to SW4P are prevented.

The same applies when the signal B1N is input. In this case, the AND gate 87A is opened to output the signal SW1N, and the switch SW1N is closed, while A
Since all the ND gates 87B to 87D are closed,
Even if the signals B2N to B4N are input, the signals SW2N to SW4N are not output. As a result, only one signal is output from the signal SW1N to the signal SW4N in this priority order, and the switches SW1N to
A short circuit of the unit cell due to the simultaneous operation of SW4N is prevented.

As described above, in the present embodiment, even if a signal that short-circuits the cells 1A to 1D is output due to a malfunction of the control circuit 4 or a program error in the control circuit 4, the cells 1A to 1D will be affected. It can prevent short circuit
The assembled battery can be charged and discharged while maintaining safety.

Further, in the present embodiment, with respect to the closing operation signal of one positive side switch, only the closing command of the negative side switch forming a pair with the closing operation signal and the negative side switches within a predetermined number range on the lower potential side is issued. By making it effective, the number of batteries connected to the capacitor is limited. That is, the closing operation signal of one positive side switch is input so as to open each closing command gate circuit of the negative side switch in the range of the number of desired lower potential side switches. All other negative side switch closing commands are guarded so that they are not output. At the time of voltage measurement, one positive side closing actuation signal is input only to the closing command gate circuit of one negative side switch forming a pair with it.

That is, in the control device of this embodiment, when the signal SW1P is output, the AND gates 87A to 87A.
Since 87C is open, when the signals B1N to B3N are input, the signals SW1N to SW3N are output accordingly. However,
Since the AND gate 87D is closed, the signal SW4N is not output even if the signal B4N is input. Further, when the signal SW2P is output, only the AND gates 87B to 87D are opened, and when the signals B2N to B4N are input, the signal SW corresponding to these is output.
2N to SW4N are output, but signals for activating other switches are not output. As a result, only the series voltage of the three or less unit cells 1A to 1D is always applied to the capacitor 2, thereby avoiding the application of the overvoltage. In this way, excessive voltage is prevented from being applied to the capacitor,
The battery pack can be charged and discharged while maintaining safety.

When measuring the voltage of each unit cell 1A-1D, the control circuit 4 outputs the signal MES and the AND gates 84A-84D are closed. As a result, the signals SW1P to SW
Only AND gates 87A to 87D outputting 4P are opened, and signals SW1N to SW4N are output corresponding to the signals B1N to B4N. That is, in the case of measuring the voltage of the single cells 1A to 1D, only the switches SW1N to SW4N corresponding to the closed switches SW1P to SW4P are closed and the single cells 1A to 1D are closed.
Voltage measurement for each D is guaranteed, and these single cells 1
Short circuits A to 1D are prevented in advance. Thus, at the time of voltage measurement, only one unit cell is reliably connected to the voltmeter, so that safe and accurate voltage measurement can be performed.

(Other Embodiments) First to Fourth Embodiments
A relay or the like may be used instead of the FET switch of the embodiment. Further, a resistor for limiting the current value flowing into or out of the auxiliary charge / discharge device may be provided, which allows the FET switch and the like to have a small capacity.

In the first and second embodiments described above, the first series battery group and the third series battery group are composed of two unit cells, but they may be composed of three or more unit cells.
In addition, both of the ones charged from the first series battery group and the third series battery group through the auxiliary charger / discharger are single cells, but each of them is composed of two or more single cells and is A second series battery group charged by one series battery group and a fourth series battery group charged by a third series battery group can be used. However, if the number of cells forming each series battery group is increased, the uniformization of the charge level or the discharge level of each cell becomes rough.

In each of the above-described embodiments, the charging device or discharging device is activated only when a unit cell is about to be overcharged or overdischarged. Instead of this, during charging or discharging. In the entire process, the electric charge may be transferred from the cell having a high charge level to the cell having a low charge level so that the charge state or the discharge state of the cell can be always made uniform.

[0066]

As described above, according to the charging / discharging device for a single cell of the present invention, it is possible to avoid wasteful consumption of charging energy, and it is small in size and low in cost and only overcharges the single cell. In addition, over-discharge can be prevented, and efficient charging and discharging of the assembled battery can be realized.

[Brief description of drawings]

FIG. 1 is a schematic block configuration diagram of a charging / discharging device showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a main part of a charging / discharging device.

FIG. 3 is a flowchart of a control circuit during charging operation.

FIG. 4 is a flowchart of a control circuit at the time of discharge operation.

FIG. 5 is a conceptual graph explaining the operation of the charging / discharging device.

FIG. 6 is a circuit diagram of a main part of a charging / discharging device showing a second embodiment of the present invention.

FIG. 7 is a circuit diagram of a main part of a charging / discharging device showing a third embodiment of the present invention.

FIG. 8 is a circuit diagram of a main part of a charging / discharging device showing a fourth embodiment of the present invention.

FIG. 9 is a main part circuit diagram of a charging / discharging device showing a fifth embodiment of the present invention.

FIG. 10 is a circuit diagram of a short circuit prevention circuit.

[Explanation of symbols]

1A, 1B, 1C, 1N ... Single cell, 2 ... Capacitor, 3
A, 3B, 3C, 3N ... Voltmeter, 4 ... Control circuit, 5 ... Switching circuit, 7A, 7B ... Battery module, 8 ... Short circuit prevention circuit, CB ... Battery pack.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-10-84627 (JP, A) JP-A-11-98698 (JP, A) JP-A-6-319287 (JP, A) JP-A-56- 71433 (JP, A) JP-A-9-285028 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02J ^7/ 00-7/36

Claims (6)

(57) [Claims] 1. A plurality of cells connected in series to form an assembled battery, an auxiliary charger / discharger, a charge state detecting means for detecting a charge state of each of the cells, and an overcharged battery during charging of the assembled battery. When a unit cell that is about to be charged is generated, the unit cell that is about to be overcharged and an appropriate number of one or more adjacent unit cells are selected as the first series battery group, and the first series battery group is selected. After connecting in parallel to the auxiliary charger / discharger, the unit cell having the lowest charge level at this time is selected from the unit cells, or includes the unit cell having the lowest charge level from the first series battery group. A small number of adjacent cells are selected as the second series battery group, and a switching operation for connecting the single battery cell having the lowest charge level or the second series battery group in parallel to the auxiliary charger / discharger is performed. a charging time of switching and connecting means for repeating the previous
At the time of switching operation of switching connection means during charging, a predetermined number or less
So that only the unit cell of the above is connected to the auxiliary charger / discharger
A battery charger for an assembled battery, comprising: 2. A battery pack according to claim 1, further provided with a short-circuit preventing means for said during switching operation so as not to connect the positive and negative sides of each cell directly of the charging time of switching and connecting means Charging device. 3. A plurality of cells connected in series to form an assembled battery, an auxiliary charger / discharger, a discharge state detecting means for detecting a discharge state of each of the cells, and an overcharged battery during discharging of the assembled battery. When a unit cell that is about to be discharged is generated, the unit cell having the highest charging level at this point in time and a suitable number of unit cells adjacent thereto are selected as the third series battery group, and the third unit cell is selected.
After connecting the series battery group of in parallel to the auxiliary charger / discharger,
A fourth series battery is selected from among the single cells, which is close to overdischarging, or an appropriate number of adjacent cells which are smaller than the third series battery group and which include the single cells near overdischarge. A discharge device for an assembled battery, which is selected as a group, and includes discharge-time switching connection means for repeating a switching operation for connecting the unit cells near the overdischarge or the fourth series battery group in parallel to the auxiliary charger / discharger. . 4. The discharge of the assembled battery according to claim 3 , further comprising short-circuit prevention means for preventing the positive electrode side and the negative electrode side of each unit cell from being directly connected during the switching operation of the discharge time switching means. apparatus. 5. A connection limiting means is further provided for limiting only a predetermined number or less of single cells to be connected to the auxiliary charger / discharger during the switching operation of the discharge switching / connecting means.
5. The battery pack discharge device according to 3 or 4 . 6. A plurality of unit cells that are connected in series to form an assembled battery, an auxiliary charger / discharger, a charge level detection unit that detects a charge level of each of the unit batteries, and a discharging unit for discharging the assembled battery. The unit cell having the highest charge level or one or more appropriate number of unit cells including the unit cell having the highest charge level and adjacent to the unit cell is selected as the third series battery group, and the unit cell having the highest charge level is selected. After connecting the unit cells or the third series battery group in parallel to the auxiliary charger / discharger, the unit cell having the lowest charge level is selected at this point, or the unit cell including the unit cell having the lowest charge level is selected. The number of adjacent cells smaller than the number of the series battery groups of 3 is selected as the fourth series battery group, and the cells having the lowest charging level or the fourth series battery group are connected in parallel to the auxiliary charger / discharger. Repeat the switching operation to connect to A discharge device for an assembled battery, comprising: discharge connection switching means.