JP2000209782A - Charge/discharge controller for combined battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the performance of unit cells constituting a combined battery equal to each other without overcharging any one of the cells, when the performance of the cells varies. SOLUTION: Variation between SOCs of cells constituting a combined battery is found (S120), and the SOC of the combined battery is controlled so that the SOC may become a target SOC by setting a value SOC1, having high charging/discharging efficiency, as the target SOC when the variation falls within a prescribed range (S160) or a value SOC2 found based on the temperature T of the combined battery at the target SOC, when the variation does not fall within the range (S180 and S190). Since the value SOC2 is set as a chargeable/dischargeable SOC that can reduce the variations between the SOCs of the cells constituting the combined battery more than desired variation, the performance of the cells can be made equal to each other without overcharging any one of the cells.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a charge / discharge control device for an assembled battery, and more particularly, to a charge / discharge control device for controlling the charge / discharge of an assembled battery in which a plurality of batteries are connected in series.

[0002]

2. Description of the Related Art Conventionally, as this type of battery charge / discharge control device, when a battery pack is left unused for a long time, the battery pack is charged for a longer time than a normal charge time. One has been proposed (for example, Japanese Utility Model Laid-Open No. 2-263).
No. 47). According to this charge / discharge control device, when the battery pack is left unused for a long time, the internal resistance and the induced voltage of each cell constituting the battery pack vary, but the battery is charged for a longer time than the normal charging time. It is said that this allows each battery to have uniform performance.

[0003]

However, in such a conventional battery charge / discharge control device, there is a problem that the cells are overcharged and the cells are deteriorated. Among the cells that have been left undisturbed for a long period of time, there are cells that have a higher chargeable discharge capacity and are distributed in a higher direction. If the cells distributed in the higher charging capacity are charged for a longer time than the normal charging time, overcharging may occur.

[0004] Variations in the performance of single cells occur not only when they are left for a long time, but in the conventional charge / discharge control device for a battery pack, the battery pack does not operate unless the battery is left for a long time. There was also a problem that the cells could not have uniform performance.

An object of the present invention is to provide an apparatus for controlling charging and discharging of a battery pack to equalize its performance without overcharging any of the cells constituting the battery pack. Further, the battery charging / discharging control device of the present invention aims at equalizing the performance of the cells even when the performance of the cells varies even though the batteries are not left for a long time. One.

[0006]

Means for Solving the Problems and Actions and Effects Thereof The battery charging / discharging control apparatus of the present invention employs the following means in order to at least partially achieve the above object.

A charge / discharge control apparatus for a battery pack according to the present invention is a charge / discharge control apparatus for controlling charge / discharge of a battery pack comprising a plurality of batteries connected in series, and one or more of the battery packs constituting the battery pack. State detecting means for detecting the state of a plurality of blocks of the battery, state determining means for determining the state of the battery pack based on the detected states of the plurality of blocks, and the state detected by the state detecting means. A variation determination unit configured to determine whether a variation in the state of the plurality of blocks is within a predetermined range based on a state of the plurality of blocks; and when the determined variation is within the predetermined range, the state of the battery pack is determined. Controlling the charge and discharge of the battery pack to be in a first predetermined state, and when the variation is not within the predetermined range, the state of the battery pack differs from the first predetermined state and the variation converges Comprise a state control means for controlling the charging and discharging of said set battery so as to be a second predetermined state which moves countercurrently to the gist of the.

According to the battery pack charge / discharge control device of the present invention, when the variation of the state of the plurality of blocks is not within the predetermined range, the state of the battery pack is controlled to move in the direction in which the variation converges. It is also possible to cope with a variation in the state of a plurality of blocks that is not caused by neglect. In addition, since the second predetermined state can be set so as not to be overcharged even in a block in which the charge capacity that can be discharged is distributed in a higher direction, deterioration of the battery caused by overcharging the battery constituting the assembled battery is prevented. be able to. In addition,
The “plurality of blocks composed of one or more batteries constituting the assembled battery” include not only blocks composed of two or more batteries connected in series but also blocks composed of only one battery. That is, “a plurality of blocks including one or more batteries” can be replaced with “each battery”.

In the charging / discharging control apparatus for a battery pack according to the present invention, the state detecting means detects a dischargeable charge capacity charged in each of the plurality of blocks as a state of the plurality of blocks. Alternatively, the state detection means may be means for detecting the voltages of the plurality of blocks as the states of the plurality of blocks.

In the charge / discharge control apparatus for a battery pack according to the present invention, the variation determining means may include, in addition to the determination,
Means for determining that the variation is not within the predetermined range every time a predetermined time elapses, or means for detecting the integrated value of charge and discharge of the plurality of blocks as the state of the plurality of blocks The variation determining means may be means for determining that the variation is not within the predetermined range when the integrated value of charging and discharging detected by the state detecting means reaches a predetermined value. In this way, the variation can be converged before the state of the plurality of blocks greatly varies.

Alternatively, in the charging / discharging control apparatus for a battery pack according to the present invention, the state determination means is configured to charge the battery pack based on the states of the plurality of blocks detected by the state detection means. Means for calculating a capacity and determining the charge capacity as a state of the battery pack, wherein the first predetermined state is a predetermined charge capacity, and the second predetermined state is a charge capacity larger than the predetermined charge capacity May be used.

Further, in the battery pack charge / discharge control device of the present invention, a temperature detecting means for detecting a temperature of the battery pack, and a predetermined state setting for setting the second predetermined state based on the detected temperature. Means may be provided. The state in which the variation in the state of a plurality of blocks can be converged changes depending on the temperature of the battery pack,
In an assembled battery in which the efficiency in which the variation can be converged changes depending on the temperature of the assembled battery, it is possible to control the battery to a more appropriate state or to improve the charging efficiency.

[0013] In the charging / discharging control apparatus for an assembled battery according to the aspect in which the charge capacity as the second predetermined state is set based on the temperature of the assembled battery, the predetermined state setting means includes a battery charger for detecting the temperature of the assembled battery detected by the temperature detecting means. The charging capacity may be set as the second predetermined state as the temperature increases.

In the charging / discharging control apparatus for an assembled battery according to the present invention including these aspects, when the variation determining means determines that the variation is not within the predetermined range, the state controlling means performs the determination after the determination. It may be a means for controlling charging and discharging of the battery pack so that the state of the battery pack becomes the second predetermined state for a predetermined time regardless of the determination made by the variation determination means. This makes it possible to increase the convergence rate of the variation in the state of the block, thereby preventing the determination that the variation does not frequently fall within the predetermined range.

[0015]

Next, embodiments of the present invention will be described with reference to examples. FIG. 1 is a schematic configuration diagram illustrating the schematic configuration of a battery pack charge / discharge control device 40 according to an embodiment of the present invention. As shown in the drawing, the battery pack charge / discharge control device 40 of the embodiment is connected to a battery pack 20 formed by connecting n unit batteries in series and a load 30 for charging / discharging the battery pack 20.

The charging / discharging control device 40 of the embodiment includes a battery pack 2
0, a voltage measuring device 42 composed of a plurality of voltmeters for measuring the voltages V1 to Vn of the cells, an ammeter 44 for measuring the current I flowing through the battery pack 20, and a temperature for measuring the temperature T of the battery pack 20. A total 46, an electronic processing device 50 that controls the entire charge / discharge control device 40 and controls the driving of the load 30, and a clock signal CL is sent to the electronic processing device 50 at predetermined timings.
Clock oscillation circuit 60 for outputting the charge and discharge control device 40
And a power supply circuit (not shown) for supplying necessary power to each section.

The electronic processing unit 50 is a one-chip microcomputer composed mainly of a CPU 52,
An internal ROM that stores processing programs in advance
54, an internal RAM 56 for temporarily storing data,
Various input ports and output ports are provided.
The input ports include the voltages V1 to Vn of the cells constituting the battery pack 20 measured by the voltage measuring device 42 and the ammeter 4.
4, the temperature T measured by the thermometer 46, the clock signal CL output from the clock oscillation circuit 60, and the like are input.
A control signal J for driving and controlling the load 30 is output.

The charging / discharging control device 40 of the embodiment configured as described above executes a charging / discharging control routine illustrated in FIG.
s) to control the charging and discharging of the battery pack 20. The timing of executing the illustrated charge / discharge control routine is measured by counting the clock signal CL input from the clock oscillation circuit 60. Hereinafter, the charge / discharge control of the battery pack 20 by the charge / discharge control device 40 based on the charge / discharge control routine will be described.

When the charge / discharge control routine is executed, the CP
U <b> 52 first executes a process of reading the voltages V <b> 1 to Vn of each cell measured by the voltage measuring device 42, the current I measured by the ammeter 44, and the temperature T of the battery pack 20 measured by the thermometer 46. (Step S100). Next, from the read voltages V1 to Vn and the current I, the SOC (State of Charge is abbreviated and usually expressed in%) of each cell and the SOC of the battery pack 20 are calculated (step S110). The SOC of each cell can be calculated from the relationship between the currents I and the voltages V1 to Vn of each cell. Although the SOC of the assembled battery 20 may be calculated from the relationship between the sum of the voltages V1 to Vn of the individual cells and the current, in the embodiment, the SOC is obtained by the arithmetic average of the SOC of each of the individual cells.

Next, the calculated variation in the SOC of each cell is determined (step S120), and it is determined whether or not the determined variation is within a predetermined range (step S130). As the variation in the SOC of each unit cell, its variance can be used, or the range of distribution can be used.
Also, the deviation between the median and the farthest value can be used. The predetermined range is set as a range in which the variation in the SOC of each cell can be tolerated, such as the type of the cell, the number of the cells, the variation as a product of the cell, the SOC of the assembled battery 20 to be controlled, and the like. Defined by

When the variation of the SOC of each cell is within a predetermined range, it is confirmed that the value SOC2 is not set to the current target SOC (step S140), and the target S is determined.
The value SOC1 is set to OC (step S160). Here, the value SOC1 is set as an SOC that does not hinder the operation of the load 30 and can efficiently charge and discharge the battery pack 20, and includes the operating characteristics of the load 30 and the charge and discharge efficiency of the battery pack 20. It is determined by such as. The value SOC2 and the processing in step S150 will be described later. Then, the value of the counter C is reset to 0 (step S170), the drive of the load 30 is controlled so that the SOC of the battery pack 20 becomes the target SOC (step S210), and the present routine ends. The counter C will also be described later.

When the variation of the SOC of each cell is not within the predetermined range, it is determined that the variation of the SOC of each cell is not within the allowable range, and the value SOC2 obtained based on the temperature T of the battery pack 20 is set to the target SOC. (Step S
180, S190). The value SOC2 is set as a chargeable / dischargeable SOC that can make the variation of the SOC of each of the cells constituting the assembled battery 20 smaller than the desired variation. It is determined by the range. FIG. 3 shows an example of the relationship between the temperature T of the battery pack 20 and the value SOC2 in a battery of a type that can reduce the variation in the SOC of each cell by increasing the SOC, and the target SOC is set to 50% and 70%. FIG. 4 and FIG. 5 show an example of the distribution of the SOC of each unit cell at the time of the above. As shown in FIGS. 4 and 5, the distribution of the SOC of each cell is obtained when the drive of the load 30 is controlled with the target SOC being 70% as compared with the case where the drive of the load 30 is controlled with the target SOC being 50%. Is smaller. Therefore, the SOC at which the distribution of the SOC of each unit cell becomes a desired distribution can be set to the value SOC2, and such a value SOC2 is used in the embodiment. The broken lines in the figure illustrate the SOC distribution of each unit cell when the battery pack 20 is discharging or the battery pack 20 is being charged by driving the load 30 at each target SOC. is there. In addition, as shown in FIG.
Since the SOC that causes the variation of the OC varies depending on the temperature of the battery pack 20, such a relationship is stored in the internal ROM 54 as a map in step S180 of the embodiment.
Given a temperature T of the battery pack 20, a value SOC2 corresponding to the temperature T is derived from the map.

After setting the value SOC2 to the target SOC in this way, the counter C is incremented (step S200), and the drive of the load 30 is controlled so that the SOC of the battery pack 20 becomes the target SOC (step S210). End the routine. The counter C indicates that the target SOC has a value S
Incremented while OC2 is set,
When the value SOC1 is set in OC, the value is reset to 0.

Next, at step S130, the SO
C is within a predetermined range and the target SO
A case where the value SOC2 is set in C will be described. In this case, the variation in the SOC of each unit cell is once out of the predetermined range, and steps S180 and S1
90, the value SOC2 is set to the target SOC, and the load 3
0 is a case where the variation of the SOC of each cell returns to the predetermined range again after executing the equalization process in which the drive control is performed. In this case, the counter C is compared with the threshold value Cref (step S150). When the counter C is equal to or smaller than the threshold value Cref, it is determined that the variation in the SOC of each cell has not sufficiently converged, and the steps S180 to S2 are performed.
A process for driving the load 30 by setting the value SOC2 to the target SOC of 10 is executed, and when the counter C is larger than the threshold value Cref, it is determined that the variation in the SOC of each cell has sufficiently converged, and the process proceeds to step S160. The value SOC1 is set to the target SOC in S170 and S210, and the load 3
Then, a process for controlling the drive of 0 is executed. Here, the threshold Cre
f is set as the time required for the variation of the SOC of each cell to sufficiently converge when the load 30 is drive-controlled with the value SOC2 as the target SOC. Is determined according to the frequency of execution.

According to the assembled battery charge / discharge control device 40 of the embodiment described above, when the SOC variation of each cell is not within the allowable range, the SOC of the assembled battery 20 is converged so that the SOC variation of each cell converges. Since the SOC is controlled, the battery pack 20
Irrespective of non-use for a long time, the performance of each cell can be equalized, and any of the cells constituting the assembled battery 20 can be prevented from being overcharged. As a result,
The performance of the battery pack 20 as a whole can be improved, and the durability of the battery pack 20 as a whole can also be improved. In addition, since the target SOC used to converge the variation in the SOC of each cell is set according to the temperature T of the battery 20, the charging of the battery 20 when the performance of each cell is equalized is set. Discharge efficiency can be improved.

In the charge / discharge control device 40 of the embodiment, the value SOC1, which is a predetermined SOC, is set to the target SOC when the variation in the SOC of each cell is within the allowable range.
This value SOC1 may be changed according to the temperature T of the battery pack 20. FIG. 6 shows the temperature T and SO of the battery pack 20.
An example of the relationship between C and the charge / discharge efficiency η is shown. As shown, the relationship between the charging and discharging efficiency η of the battery pack 20 and the SOC changes depending on the temperature T of the battery pack 20. Therefore, if the value SOC1 is set based on the temperature T of the battery pack 20 so that the charging / discharging efficiency η of the battery pack 20 becomes high within a range where the driving control of the load 30 is not hindered, Efficiency can be improved.

In the charging / discharging control device 40 of the embodiment, the processing of equalizing the performance of each cell is performed when the variation of the SOC of each cell is not within the allowable range. Then, the equalization process may be performed even when the variation in the SOC of each cell is within the allowable range. FIG. 7 shows a part of an example of a charge / discharge control routine for performing this processing. In the charge / discharge control routine of FIG. 7, steps S300 to S3 are performed instead of the processing of steps S160 to S200 of the charge / discharge control routine of FIG.
70 is executed. In the charge / discharge control routine of FIG. 1, when the variation of the SOC of each cell is within a predetermined range, it is confirmed that the value SOC2 is not set to the current target SOC, and the value SOC1 is set to the target SOC ( Steps S150 and S160), in the charge / discharge control routine of FIG. 7, after confirming that the value SOC2 is not set to the current target SOC, the second counter D is set to the threshold Dr.
ef (step S300), and when the second counter D is smaller than the threshold value Dref, the target SOC is set to the value SOC1.
Is set (step S310). The second counter D is
When the equalization processing is performed, the value is reset to 0 (step S370), and when the equalization processing is not performed, the value is incremented (step S330). Therefore,
By appropriately setting the threshold value Dref, the equalization processing is performed when a predetermined time has elapsed after the equalization processing is performed, even when the variation in the SOC of each cell is within an allowable range. According to such a modification, the performance of each cell can be equalized periodically.

Further, the charge / discharge control device 4 of the battery pack of the embodiment
At 0, the equalization processing was performed when the variation in the SOC of each cell determined from the voltages V1 to Vn of each cell and the current I was not within a predetermined range. However, in the modification of the charge / discharge control routine of FIG. As partially shown, the voltage V1 to Vn of each cell
May be performed when the variation is not within the predetermined range. Alternatively, as shown in a part of a modification of the charge / discharge control routine in FIG. The equalization processing may be performed when the value becomes larger than the value. In these cases, steps S410 to S430 of the charge / discharge control routine of FIG. 8 and steps S410 of the charge / discharge control routine of FIG. 9 are replaced with the processing of steps S110 to S130 of the charge / discharge control routine of FIG.
510 to S530 may be executed. By doing so, the performance of each unit cell can be equalized based on the variation of the voltages V1 to Vn of each unit cell and the integrated value of charge / discharge of each unit cell.

In the battery charge / discharge control device 40 of the embodiment, the SOC of each cell of the battery pack 20 is calculated, and it is determined whether or not to perform the cell equalization process based on the variation. SO per block composed of two or more cells
It is also possible to calculate C and determine whether or not to perform the cell equalization process based on the variation thereof. By doing so, the measurement of each block may be performed instead of the measurement of the voltages V1 to Vn of the individual cells, so that the voltage measuring device 42 can be simplified and the time required for calculating the SOC can be reduced. Can be.

The embodiments of the present invention have been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various embodiments may be made without departing from the gist of the present invention. Of course, it can be carried out.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an outline of a configuration of a battery pack charge / discharge control device 40 according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an example of a charge / discharge control routine executed by a CPU 52;

FIG. 3 is a graph showing an example of a relationship between a temperature T of the battery pack 20 and a value SOC2.

FIG. 4 is a graph showing an example of an SOC distribution of each unit cell when a target SOC is set to 50%.

FIG. 5 is a graph showing an example of an SOC distribution of each unit cell when a target SOC is set to 70%.

FIG. 6 is a graph showing an example of the relationship between the temperature T of the battery pack 20, the SOC, and the charging / discharging efficiency η.

FIG. 7 is a flowchart illustrating a part of a charge / discharge control routine according to a modified example.

FIG. 8 is a flowchart illustrating a part of a charge / discharge control routine according to a modified example.

FIG. 9 is a flowchart illustrating a part of a charge / discharge control routine according to a modified example.

[Explanation of symbols]

20 assembled batteries, 30 loads, 40 charge / discharge control devices, 4
2 Voltage measuring device, 44 ammeter, 46 thermometer, 50 electronic processing unit, 52 CPU, 54 internal ROM, 56
Internal RAM, 60 clock oscillation circuit.

Claims (9)

[Claims] 1. A charge / discharge control device for controlling charging / discharging of a battery pack formed by connecting a plurality of batteries in series, wherein a state of a plurality of blocks comprising one or more batteries constituting the battery pack is determined. State detecting means for detecting; state determining means for determining the state of the battery pack based on the detected states of the plurality of blocks; and the plurality of states based on the states of the plurality of blocks detected by the state detecting means. A variation determining means for determining whether or not the variation of the state of the block is within a predetermined range; and when the determined variation is within the predetermined range,
Controlling the charging and discharging of the battery pack so that the state of the battery pack is in a first predetermined state, and when the variation is not within the predetermined range, the state of the battery pack is different from the first predetermined state; A state control means for controlling charging and discharging of the battery pack so as to be in a second predetermined state in which the variation moves in a direction in which the variation converges. 2. The charge / discharge control device according to claim 1, wherein the state detection means detects a dischargeable charge capacity charged in each of the plurality of blocks as a state of the plurality of blocks. . 3. The charge / discharge control device according to claim 1, wherein said state detection means is means for detecting voltages of said plurality of blocks as states of said plurality of blocks. 4. The charge / discharge control device according to claim 1, wherein the variation determination unit is configured to determine that the variation is not within the predetermined range every time a predetermined time elapses, in addition to the determination. . 5. The charge / discharge control device according to claim 1, wherein the state detecting means is means for detecting an integrated value of charging / discharging of the plurality of blocks as a state of the plurality of blocks; A charge / discharge control device, wherein the determination means is means for determining that the variation is not within the predetermined range when the integrated value of charge / discharge detected by the state detection means reaches a predetermined value. 6. The charge / discharge control device according to claim 1, wherein the state determination unit charges the battery pack based on states of a plurality of blocks detected by the state detection unit. Calculating a dischargeable charge capacity, and determining the charge capacity as a state of the battery pack. The first predetermined state is a predetermined charge capacity, and the second predetermined state is: A charge / discharge control device having a charge capacity larger than the predetermined charge capacity. 7. The charge / discharge control device according to claim 1, wherein a temperature detecting means for detecting a temperature of the battery pack, and the second predetermined state is set based on the detected temperature. A charge / discharge control device comprising: a predetermined state setting unit for setting. 8. The apparatus according to claim 6, wherein said predetermined state setting means sets a smaller charging capacity as said second predetermined state as the temperature of the battery pack detected by said temperature detecting means increases. 8. The charge / discharge control device according to 7. 9. The state control unit, when the variation determining unit determines that the variation is not within the predetermined range, regardless of a determination made by the variation determining unit after the determination. 9. The charge / discharge control device according to claim 1, wherein the charge / discharge control unit controls charging / discharging of the battery pack so that the state becomes the second predetermined state.