JP2000228831A - Correction method for irregularity in set battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a circuit simple and less expensive by a method wherein voltages of unit batteries are compared relatively in every battery module so as to correct its irregularity and an irregularity between battery modules is corrected. SOLUTION: When a battery module 7a is not being charged, whether the module is being discharged or not is checked. When the module is being discharged and when the voltage of a unit battery 1a, that of a unit battery 1b and that of a unit battery 1c are less than a charging completion value, a module control part 6 checks whether a preset discharge completion value or lower is detected in the voltages of the respective unit batteries 1a, 1b, 1c. When the discharge completion value or lower is not detected, whether an instruction to turn on all discharging means is issued from an overall control part 8 or not is checked. When the instruction is not issued, the voltages of the respective unit batteries 1a, 1b, 1c are compared. Whether a prescribed value 1 or higher which is prescribed in advance is detected in the relative voltage difference between the unit batteries or not is checked. When any of the unit batteries whose relative voltage difference is at the prescribed value 1 or higher is detected, all the discharge means are turned on. When the discharge relative difference is less than the prescribed value 1, all the discharge means are turned off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for correcting variations in charging of each unit cell of a power storage device using an assembled battery composed of a plurality of secondary cells. The present invention relates to a method and an apparatus for correcting variations in the state of charge of a battery pack in which a plurality of battery modules connected in series and parallel are connected in series or in series and parallel between cells in each battery module and between battery modules.

[0002]

2. Description of the Related Art When secondary batteries are connected in series and used, the state of charge differs due to variations in characteristics between the batteries.
Since there is a risk of overcharging or overdischarging, the overcharge and overdischarge of each battery is detected, and the current at the time of charging or (and) discharging is bypassed by a circuit connected in parallel to each battery, and the state of charge of each battery Has been proposed in Japanese Patent Application Laid-Open No. 5-111177.

[0003]

Overcharging and overdischarging are detected based on the voltage between terminals of each battery. At the time of overcharging, the overcharged battery is discharged or the charging current is bypassed to increase the amount of charge of other batteries. Therefore, the conventional method of reducing the voltage difference between the terminals in terms of the voltage between the terminals and disconnecting the overdischarged battery in the event of overdischarge to prevent further discharge is a simple and effective method. Since the current is bypassed after the discharge is detected, there is a problem that deterioration of the battery due to overcharge or overdischarge cannot be sufficiently prevented.

Furthermore, electric vehicles and home electric storage devices have a problem that the circuit is complicated and expensive because the number of series cells in the assembled battery is increased and used to increase the efficiency.

An object of the present invention is to solve such a problem.

[0006]

In order to solve the above-mentioned problems, according to the present invention, a battery module is constructed by connecting a plurality of unit cells each composed of a secondary battery in series or in series-parallel. In a power storage device using an assembled battery configured by connecting a plurality of such battery modules in series or in series / parallel, in each battery module, means for detecting a terminal voltage of each cell constituting the battery module is provided. A discharge means is provided in parallel with each cell, and the voltage of each cell in each battery module is compared at the time of charge / discharge or (and / or standby), and a cell having a higher voltage is discharged or charged by the discharge means. Means for reducing the voltage difference between the cells in the battery module, correcting the variation between the cells, and monitoring the voltage of each battery module. When the voltage difference between the modules becomes equal to or greater than a predetermined value, the discharging means in the battery module having a high voltage are simultaneously operated, and all the cells in the battery module are simultaneously discharged or the charging current is bypassed. The same circuit is used for each module by compensating for the variation in voltage between the battery modules, compensating for the variation by relative comparison of the cell voltages for each battery module, and compensating for the variation between the battery modules. Can be used to simplify the circuit.

Further, according to the present invention, an overcharge value that defines the overcharge voltage of the cell at the time of charging and a charge completion value that is smaller than the overcharge value that defines the charge end voltage of the cell are determined in advance. When the voltage of any one of the cells in the battery module reaches the charge completion value, a charge completion signal is output from the battery module. When the signal is output, the charging current is changed to the charge completion value of the cell. At this time, the discharging means connected in parallel to the cell limits the dischargeable current value or less, and all the discharging means connected in parallel to each cell in the battery module that issued the charge completion signal are operated. The charging current was bypassed, and all the battery modules output a charging completion signal, when any of the cell voltages became overcharged, when the allowable charging time elapsed, and when the battery pack was discharged. Place So as to end the charging of the two pairs batteries were to be substantially fully charged all of the cells.

According to the third aspect of the present invention, an overdischarge value that defines the overdischarge voltage of the cell at the time of discharging and a discharge completion value that is larger than the overdischarge value that defines the discharge end voltage of the cell are determined in advance. When the voltage of any one of the cells in the battery module reaches the discharge completion value, a discharge completion signal is output from the battery module. When the signal is output, the discharge of the battery pack is completed and the discharge completion is completed. The discharge means connected in parallel to each cell in all the battery modules other than the battery module that issued the signal is operated to discharge, and all the battery modules output a discharge completion signal; When the battery reached an overdischarge value and when charging was started, the discharge by the discharging means was terminated, so that all the cells could be almost completely discharged.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. It should be noted that the embodiments described below exemplify a method for embodying the technical idea of the present invention, and do not limit the claims of the present invention. Further, the following embodiment describes a case where a lithium ion secondary battery is used, but the type of the secondary battery is not limited to this.

FIG. 1 is a configuration diagram of a power storage device according to an embodiment of the present invention. Cell 1a using a lithium ion secondary battery,
1b, 1c are connected in series, and each unit cell 1a, 1c
Both ends of b and 1c are connected to terminal voltage detecting means 2,
In parallel with each of the cells 1a, 1b, 1c, a discharge resistor 3a, 3
b, 3c and discharging means 5a, 5b, 5c constituted by a series circuit of switching means 4a, 4b, 4c. Each of the switching means 4a, 4b, and 4c is connected to the module control unit 7, and each of the switching means 4a, 4b, and 4c opens and closes in response to a signal from the module control unit 6, respectively. These are collectively housed in one housing to constitute the battery modules 7a and 7b.

Each of the battery modules 7a and 7b is connected to an overall control unit 8, and the overall control unit 8 controls each of the battery modules 7a and 7b.
a and 7b are managed and controlled. An assembly of battery modules 7a and 7b connected in series constitutes an assembled battery 9,
The positive electrode side of the battery pack 9 is connected to a charge / discharge control unit 10. The charge / discharge control unit 10 and the overall control unit 8 are connected to a voltage conversion input / output unit 11 which is an external interface unit of the power storage device.

Next, a method of correcting a variation in the battery voltage of the power storage device according to the present embodiment will be described with reference to FIGS. FIG. 2 is an operation flow of variation correction in the battery modules 7a and 7b, and these processes are controlled by the module control unit 6. FIG. 3 is an operation flow when controlling charge / discharge and charge current in order to correct voltage variations between the battery modules 7a and 7b. The overall control unit 11 controls the charge / discharge control unit 9 to perform the control.

The module control unit 6 includes the terminal voltage detecting means 2
, The unit voltages of the cells 1a, 1b, 1c are detected and compared (12), and it is checked whether charging is in progress (13).
If charging is in progress, it is checked whether or not the voltage of each of the cells 1a, 1b, 1c is higher than a preset charging completion value (15). When there is a single cell having a voltage equal to or higher than the charge completion value, the module control unit 6 sets the battery module 7a
Is notified to the overall control unit 8 (16), and all the discharging means 5a, 5b and 5c in the battery module 7a are turned on (17).

Next, the module controller 6 controls each of the cells 1a,
The voltages of 1b and 1c are compared with an overcharge value larger than a preset charge completion value (18), and when there is a single cell having a voltage higher than the overcharge value, the module control unit 6 The overall control unit 8 is notified of the overcharge of 7a (19), and the process proceeds to the next process. If there is no cell having a voltage equal to or higher than the overcharge value, the process directly proceeds to the next process.

If the battery module 7a is not charging, it is checked whether it is discharging (14). If the battery module 7a is discharging, and if the voltages of the cells 1a, 1b, 1c are being charged and the voltage of each of the cells 1a, 1b, 1c is a charge completion value, If the value is less than the predetermined value, the module control unit 6 checks whether or not there is a voltage of each of the cells 1a, 1b, 1c equal to or less than a preset discharge completion value (2).
0) If there is no value below the discharge completion value, it is checked whether or not there is an instruction to turn on all the discharging means from the overall control unit 8 (21).
By comparing the voltages of b and 1c, it is checked whether or not there is a relative voltage difference between the batteries that is equal to or more than a predetermined value 1 (22), and there is a single cell having a relative voltage difference of 1 or more. In this case, the discharging means connected in parallel to the cell is turned on (23), and then the discharging means connected in parallel to the cell having a relative voltage difference of less than the specified value 1 is turned off ( 24), move on to the next process.

If any of the cells 1a, 1b, 1c is equal to or less than the discharge completion value, the module control section 6 notifies the overall control section 8 of the completion of discharge of the battery module 7a.
(25) Subsequently, all the discharging means connected in parallel to the undischarged unit cells in the battery module 7a are turned on (26).
Also, when there is an instruction to turn on all the discharging means from the overall control unit 8 in step 21, the discharging means 5 connected in parallel to the uncompleted discharge cells in the battery module 7a is turned on (26).

Next, the module controller 6 controls each cell 1
The voltages of a, 1b, and 1c are compared with an overdischarge value smaller than a preset discharge completion value, and it is checked whether or not there is a single cell having an overdischarge value or less (27). When there is a cell having a value equal to or less than the overdischarge value, the module control unit 6 notifies the overall control unit 8 of the overdischarge of the battery module 7a (28), and all the discharge means 5a, 5b, 5c is turned off and the discharging means 5a, 5b,
The discharge at 5c is completed (29), and the process proceeds to the next process.

The module control unit 6 also turns off all the discharging means 5a, 5b, and 5c in the battery module 7a even when the power storage device is neither charging nor discharging.
9).

At this time, the overall control unit 8 compares the terminal voltage of each battery module 7a, 7b with the battery voltage information (not shown) from the module control unit 6 in each battery module 7a, 7b (30). Next, it is checked whether or not the power storage device is charging (31). If the power storage device is charging, it is checked whether or not there is a fully charged battery module (32).
When there is a fully charged battery module, charging / discharging means 9
To the discharge means 5a, 5b, 5
c is limited to a dischargeable value (33), and it is checked whether there is an overcharged battery module (34). If there is no battery module, the process proceeds to the next process. It issues an instruction signal to the control unit 9 to stop charging (35),
An instruction to turn off all discharging means in the battery modules is issued to each of the battery modules 7a and 7b (36), and the process proceeds to the next process.

If no battery module is fully charged, it is checked whether or not the relative voltage difference between the terminal voltages of the battery modules 7a and 7b is equal to or greater than a predetermined value 2 (37). If there is a battery module with a relative voltage difference of 2 or more, the overall control unit 8 issues an instruction signal to turn on all the discharging means in the battery module having a relative voltage difference of 2 or more (38). Difference is specified value 2
An instruction signal for canceling the instruction to turn on all the discharging means is issued to the battery modules less than (39), and the process proceeds to step. If there is no battery module whose relative voltage difference between the battery module terminal voltages is equal to or greater than the specified value 2, the process proceeds to step 39.

If the power storage device is not being charged, the overall control unit 8 checks whether or not the battery is discharging (40). If the battery is discharging, it checks whether or not there is a battery module that has been completely discharged (41). If there is a completed battery module, the overall control unit 8 issues a discharge stop instruction signal to the charge / discharge control unit 9 to stop discharging (42), and all battery modules in the battery module that have not completed discharging are discharged to each battery module. An instruction signal for turning on the means is issued (43).

When the overall control unit 8 issues an instruction signal to turn on all the discharging means in the battery module whose discharge has not been completed, and when the power storage device is neither charging nor discharging, the overall control unit 8 sets the It is checked whether or not there is a module (44).
If not, move on to the next process.

If there is no completely discharged battery module during discharging, it is checked whether the relative voltage difference between the terminal voltages of the battery modules 7a and 7b is equal to or greater than a predetermined value 2 (45). If there is a battery module having a voltage difference equal to or greater than the specified value 2, the overall control unit 8 issues an instruction signal to turn on all discharging means in the battery module having a relative voltage difference equal to or greater than the specified value (46). An instruction signal for canceling the instruction to turn on all the discharging means is issued to the battery module having a voltage difference of less than the specified value 2 (47), and the routine proceeds to step 44. If there is no battery module whose relative voltage difference between the battery module terminal voltages is equal to or greater than the specified value 2, the process proceeds to step 47.

In the power storage device of the present embodiment, the charge / discharge state is managed for each cell written by two-level voltage management at the time of charge and discharge, and for each battery module as described above. The voltage difference is corrected within a predetermined value and the relative voltage difference of each battery module is also corrected within a predetermined value, thereby correcting variations in the assembled batteries. Although not provided in this embodiment, it goes without saying that a correction function or the like corresponding to the battery ambient temperature may be used in combination.

[0025]

As described above, according to the present invention, the voltage variation between the cells in each battery module is corrected, and the voltage variation between the battery modules is corrected by the relative voltage difference between the battery modules. Therefore, the voltage detection unit and the discharging unit can be configured to have a simple circuit configuration,
Even if the entire battery module is replaced, the variation can be easily corrected.

Further, since the variation can be corrected without overcharging or overdischarging at the completion of charging and at the completion of discharging, a method and apparatus for correcting variation of the battery pack suitable for a power storage device having a relatively long standby time are provided. it can.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a power storage device according to a first embodiment of the present invention.

FIG. 2 is an operation flow of variation correction in a battery module.

FIG. 3 is an operation flow when controlling charging / discharging and charging current in order to correct voltage variation between battery modules.

[Explanation of symbols]

1a, 1b, 1c ... cell, 2 ... terminal voltage detecting means, 3
a, 3b, 3c: discharge resistance, 4a, 4b, 4c: switching means.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5G003 AA01 BA03 CA14 CC04 5G065 BA01 BA09 GA09 HA01 HA07 HA16 LA01 MA10 NA02 5H030 AA03 AA04 AS01 AS08 BB00 BB26 FF43 FF44

Claims (1)

[Claims] 1. A power storage device using an assembled battery formed by connecting a plurality of unit cells composed of secondary batteries in series or in series / parallel and connecting a plurality of battery modules in series or in series / parallel. Means for detecting a voltage between terminals of each cell constituting the battery module in the module,
Discharge means are provided in parallel with each cell, and the voltage of each cell in each battery module is compared at the time of charge / discharge or (and / or standby), and a cell having a higher voltage is discharged or charged by the discharge means. Means for reducing the voltage difference between the cells in the battery module, correcting the variation between the cells, and monitoring the voltage of each battery module. When the voltage difference between the battery modules becomes equal to or larger than a predetermined value, the discharging means in the battery module having a high voltage are simultaneously operated to simultaneously discharge all the cells in the battery module or to bypass the charging current. And correcting voltage variations among the battery modules.