JP5478174B2 - Charging method and system for large secondary battery - Google Patents

Description

  The present invention relates to a charging method and system for a large-sized secondary battery configured by combining a large number of cells.

  A large-sized secondary battery mounted on an electric vehicle or the like is configured by connecting cells in series or in parallel. However, in any connection method, a method of charging a large secondary battery with one charging device is employed (Patent Document 1).

  For example, as a structure of a large-sized secondary battery, as shown in FIG. 3, it is conceivable to form a battery module by combining cells and to connect two battery modules in parallel. When the charging method of Patent Document 1 is adopted for such a large-sized secondary battery connected in parallel, one charging device is connected to two battery modules connected in parallel.

JP 2008-278635 A

  By the way, since the large secondary battery is a parallel circuit, the current flowing from one charging device is shunted to a small current in each battery module. If one of the battery modules is fully charged, the secondary battery is handled as being fully charged and charging is terminated. With such a small current, the time required to fully charge the secondary battery, That is, the charging time becomes longer.

  Moreover, when there is one charging device, there is a disadvantage that charging cannot be performed at all if the charging device fails.

  In addition, the cell has a characteristic that the performance deteriorates as charge and discharge are repeated (the internal resistance increases and the discharge capacity decreases), and the progress speed of the deterioration varies from cell to cell. As described above, since the battery module is configured by combining a large number of cells, the performance of each cell gradually varies. In particular, when a large-sized secondary battery is mounted on an electric vehicle, the battery modules may be distributed at different locations depending on the installation space in the vehicle. The cell also has a characteristic that the progress speed of deterioration increases in a high temperature environment. Therefore, if the location of the battery module in the electric vehicle is different, a difference in performance occurs not only in the cell unit but also in the battery module unit. Is assumed.

  Nevertheless, when charging with a single charging device as in the past, a battery module with low degradation (low resistance) has more charging current than a battery module with high degradation (high resistance). Will flow. However, since the battery module is composed of a large number of cells, the difference in charging current between the battery modules is almost negligible for each cell, and the cells of any battery module are almost the same. Charging current flows.

  As described above, since substantially the same charging current flows through each cell, full charge is reached from a cell having a large deterioration in a battery module having a large deterioration. In order to avoid overcharging of a cell, when even one cell reaches full charge, the entire charge is terminated. Therefore, in a battery module with small deterioration, none of the cells in the battery module has reached full charge. . As a result, the overall discharge capacity is reduced, and the cruising distance, which is a problem for electric vehicles and the like, is reduced.

  In addition, since almost the same charging current flows through each cell, a cell having a larger deterioration (a larger internal resistance) is charged under a condition of severe heat generation. The deterioration of the battery module having a large deterioration is promoted, and the difference from the battery module having a small deterioration is increased. It is generally known that the larger the charging current is, the more the cell deterioration is promoted.

  The present invention was created in view of the above circumstances, and the problem to be solved is to make it possible to shorten at least the charging time (time for full charge) of the secondary battery.

The charging method of the large-sized secondary battery of the present invention is a charging method of a large-sized secondary battery in which a large-sized secondary battery in which a plurality of battery modules composed of a large number of cells are connected in parallel is charged by a charging device. A large-sized secondary battery is charged by a plurality of charging devices, the parallel connection between at least one battery module and another battery module is disconnected, and the large-sized secondary batteries are divided into a plurality of sets, and then each set of battery modules. Are individually charged by different charging devices.

When each set of battery modules is charged with the same charging current value, the charging time (time required for full charge) of the battery modules with a small deterioration becomes longer than the charging time of the battery modules with a large deterioration. In this case, of the entire charging time, it is possible to use a wasteful time during which the battery module of the group with large deterioration is not charged. Moreover, the deterioration rate of a battery module can be slowed, so that a charging current value is small. In order to reduce the deterioration rate of the battery module by eliminating such wasted time, the following is performed. That is, as in the first aspect of the invention, the deterioration state is determined for each set of battery modules, the capacity is calculated, and the charging time of the battery modules of the set with low deterioration is calculated from the capacity and the charging current value, In other words, the charging current value of the other battery module is determined from the capacity and the charging time so that the charging time of the other battery module matches the charging time.

  The group with the smallest deterioration does not include the group with the largest deterioration, but is not limited to the group with the smallest deterioration. In addition, among the other groups, there may be a group having a smaller deterioration (for example, a group having the smallest deterioration) than a group having a small deterioration.

  Therefore, when charging each of the three battery modules with a single charging device, the second deteriorated battery module is treated as a battery module with a small deterioration, and the other two battery modules are You may handle as a battery module of a set. In this case, if the battery module that has deteriorated second is fully charged at the rapid charge current value, the battery module that has deteriorated most during the charging time is fully charged at a charge current value smaller than the rapid charge current value. However, even if it is a quick charge current value, the battery module which has not deteriorated most in the charging time will not be fully charged. Nevertheless, compared to the conventional case where three battery modules connected in parallel are charged by a single charging device, the number of battery modules that are fully charged is increased, which is effective. However, it is possible to determine the charging current value of the other battery module so that the charging time of the other battery module matches the charging time of the battery module with the least deterioration, and charge the other battery module. It is most ideal for delaying the deterioration of a battery module.

Further, if there is a difference in voltage between the battery modules of each group after charging, when the battery modules of each group are connected in parallel, a circulating current (cross current) flows and the deterioration of the battery module is promoted. To prevent this, do the following: That is, as in the invention of claim 2, the deterioration state is determined for each set of battery modules, and the charging time and voltage value of the battery module of the other set are set to the charging time and voltage value of the battery module of the other set. In order to match, the charging current value of the battery module of the other set is determined on the basis of the charging current value of the battery module of the lower deterioration, and charging is performed.

The large secondary battery charging system of the present invention is a system capable of performing the large secondary battery charging method of the present invention, and is a large secondary battery in which a plurality of battery modules composed of a large number of cells are connected in parallel. A battery, an open / close section that divides a large-sized secondary battery into a plurality of sets by disconnecting a parallel connection between at least one battery module and another battery module, and opens / closes the open / close section. And a charging control unit that determines a deterioration state and determines a charging condition for each set of battery modules.

A charging system for a large-sized secondary battery according to claim 3 is a system capable of performing the charging method for a large-sized secondary battery according to claim 1 , wherein the charging control unit determines a deterioration state for each set of battery modules and has a capacity. To calculate the charging time of a battery module with a small deterioration from its capacity and charging current value, and to match the charging time of another battery module with the calculated charging time. The module is charged by determining the charging current value of the module from its capacity and charging time.

A charging system for a large-sized secondary battery according to claim 4 is a system capable of performing the charging method for a large-sized secondary battery according to claim 2 , wherein the charging control unit determines a deterioration state for each set of battery modules, and the deterioration In order to match the charging time and voltage value of the battery module of the other set with the charging time and voltage value of the battery module of the other set, the other set The charging current value of the battery module is determined and charged.

In the present invention , if each set of battery modules is individually charged with different charging devices, the maximum charging current value per unit time is larger than charging all the battery modules with one charging device. The secondary battery can be fully charged. In addition, each set of battery modules can be fully charged, and the charging capacity is larger than when charging with one charging device. When this is used in an electric vehicle, the cruising distance is extended. Further, when the charging control unit opens and closes the opening / closing unit as in claim 4, when there is an abnormality (failure) in one charging device, the large secondary battery may be charged without disconnecting the parallel connection. it can.

The inventions of claims 1 and 3 calculate the capacities of the battery modules of each set, and adjust the charging time of the battery module of the other set so that the charging time of the battery module of the other set matches the charging time of the battery module of the other set. Since the charging current value of the battery module of the group is determined, the charging time of the battery module of the large deterioration can be increased, and as a result, the charging current value can be reduced and the deterioration can be delayed.

According to the second and fourth aspects of the present invention, the charging time and the voltage value are matched with each other in the battery modules based on the battery modules in the group with small deterioration. When the battery modules of each set are connected in parallel, there is no voltage difference, so there is no circulating current (cross current) flowing from the battery module with the large voltage value to the battery module with the small voltage value. Module degradation can be delayed. Further, even if the capacity of the battery module is not calculated, it can be confirmed that the battery is fully charged if the voltage value reaches a predetermined voltage value.

It is a partially expanded block diagram which shows the charging system of a large sized secondary battery. It is a block diagram which shows the charge control part of a large sized secondary battery. It is a block diagram which shows the charging system of the conventional large sized secondary battery.

  As shown in FIGS. 1 and 2, an example of a charging system for a large-sized secondary battery according to the present invention includes a large-sized secondary battery 1, a plurality of charging devices 2, 2,. It is an electric circuit including a charging control unit 4 that monitors the large secondary battery 1 and controls the charging device 2 and the switching unit 3 while monitoring the large secondary battery 1. In addition, the charging system for the large secondary battery is connected in parallel to a load 5 (such as a motor of an electric vehicle). And the system disconnection part 6 is connected between the load 5 and the charging system of a large-sized secondary battery, and both are disconnected by this system disconnection part 6 at the time of charge.

  The large secondary battery 1 is obtained by connecting a plurality of battery modules 11, 11,. In the figure, two battery modules 11 and 11 are connected in parallel. Each battery module 11 has a configuration in which a large number of cells 12, 12,... Are connected in series or in parallel. In the figure, a plurality of cell groups 13 in which a large number of cells 12, 12,... Are connected in parallel are connected in series to form a battery module 11.

  The opening / closing part 3 is a switch and is provided at a parallel connection location of the two battery modules 11. The open / close unit 3 can be opened and closed by receiving an open / close signal from the charge control unit 4. When the open / close unit 3 is opened (separated), the large secondary battery 1 is divided into two battery modules 11 and 11. . Normally, when a current is passed from the large-sized secondary battery 1 to the load 5, the open / close unit 3 is closed and the two battery modules 11 and 11 are connected in parallel, and then the system disconnecting unit 6 is closed.

  The charging device 2 includes a direct current power source 21, an internal switch 22 that opens and closes a connection to the large-sized secondary battery 1, and a power supply controller 23 in which a CPU is built.

  The power supply controller 23 normally closes the internal switch 22 in order to charge until the voltage value of the cell 12 reaches a constant value, and captures the charge current value signal so that the charge current value becomes a desired value. A control signal is output to the power source 21. On the other hand, when the voltage value of the cell 12 reaches a certain value, the power supply controller 23 opens the internal switch 22 in order to end the charging. Even if the voltage value of the cell 12 does not reach a constant value, the power supply controller 23 opens the internal switch 22 when the voltage value of the battery module 11 reaches a certain value.

  The charging control unit 4 includes a module monitoring device 41 that monitors each set of battery modules 11 and a power supply controller 23 of the charging device 2.

  The module monitoring device 41 includes a plurality of cell voltage detectors 42, a module voltage detector 43, a current detector 44, and a module controller 45. The voltage value of the cell 12 detected by each cell voltage detector 42, the voltage value of the battery module 11 detected by the module voltage detector 43, and the charging current value detected by the current detector 44 are output to the module controller 45. These detectors 42 to 44 are connected.

  The cell voltage detector 42 is connected in parallel to each cell group 13. Since the cell group 13 includes a large number of cells 12 connected in parallel, the cell voltage detector 42 connected in parallel to the cell group 13 detects the voltage values of all the cells 12 in the cell group 13. It will be. A voltage value based on the detection result is constantly sent to the module controller 45.

  The module voltage detector 43 is connected in parallel to each set of battery modules 11. The voltage value of each set of battery modules 11 is detected, and the voltage value based on the detection result is constantly sent to the module controller 45.

  The current detector 44 detects the charging current value for each battery module 11, and the current value based on the detection result is constantly sent to the power supply controller 23 via the module controller 45.

  The module controller 45 is communicably connected to the corresponding charging device 2 (power supply controller 23). Further, the module controllers 45 are also connected so as to be able to communicate with each other, and one of them is connected so as to be able to output an open / close signal to the open / close unit 3.

  The module controller 45 communicates with the power supply controller 23 of the corresponding charging device 2 to grasp whether the corresponding charging device 2 is normal or abnormal. Each set of module controllers 45 communicates whether this is normal or abnormal, and the representative module controller 45 outputs an open signal to the open / close unit 3 when both of the two charging devices 2 are normal. The battery modules 11 are separated and divided into two sets, and each set of battery modules 11 is charged by the corresponding charging device 2. On the other hand, when there is an abnormal charging device 2, the closed state of the opening / closing unit 3 is maintained, and the two battery modules 11 and 11 are charged together with the normal charging device 2.

  Further, the module controller 45 takes in the voltage values of all the cells 12 in its own set, and determines the deterioration state of the battery module 11 in its own set before charging based on the voltage value. Specifically, the deterioration state of the battery module 11 of its own set is grasped from the voltage value of the cell 12 having the largest deterioration. This deterioration state is communicated between the module controllers 45 of each group, and the battery module 11 having the least deterioration is selected in the representative module controller 45.

  When both of the charging devices 2 are normal, the charging conditions for rapid charging are controlled by the following two examples. In the first example, the representative set of module controllers 45 calculates the charging time so that the selected set of battery modules 11 is fully charged in as short a time as possible, and other sets of batteries are calculated within the calculated charging time. The charging current values of other sets of battery modules 11 are determined according to the deterioration state so that the charging times of the modules 11 match. The charging current value is output to the power controller 23 of the corresponding charging device 2 via each set of module controllers 45. Then, the power supply controller 23 outputs a control signal so that the determined charging current value flows to the direct current power supply 21. If the voltage value detected from the module voltage detector 43 after the calculated charging time has confirmed that the battery is fully charged as calculated, the module controller 45 sends a charge stop signal to the power supply controller 23 of the charging device 2. The power supply controller 23 opens the internal switch 22 and stops charging. On the other hand, if the calculation is different, correction is performed. That is, when the full voltage is not reached when the Ta time has passed due to the voltage value detected from the module voltage detector 43, the charging is continued and the full charge is reached before the Ta time has passed. Ends charging at that time.

  The determination of the charging current value is performed as follows, for example. It is assumed that the large secondary battery 1 is composed of two battery modules. The battery module with the least deterioration is A, the capacity is Ca, the charging device corresponding to the battery module A is A, while the battery module with the most deterioration is B, the battery capacity is Cb, and the battery module B The charging device corresponding to is B. The capacity is calculated by an existing calculation method. For example, a constant current is passed through the battery module for a certain period, the internal impedance is measured from the voltage increase value, and the capacity of the battery module 11 is estimated. Alternatively, a current is passed through the battery module for a certain period, and when the current is stopped, the capacity of the battery module is estimated from the voltage increase value. It is assumed that the charging device A continuously charges the battery module A at the current value Ia, and the charging device B charges the battery module B continuously at the current value Ib. If the maximum current values of the battery module A and the battery module B are Im = Ia = Ib, the charging time Ta required to charge the battery module A as quickly as possible is Ta = Ca / Ia. On the other hand, the charging time Tb of the battery module B is Tb = Cb / Ib. Since Ca> Cb, Ta> Tb. Therefore, the battery module B is continuously charged with a current value of Ib ′ = Cb / Ta so that Ta = Tb. As a result, Ib ′ <Ib, and deterioration of the battery module B can be suppressed as compared with the conventional case. Moreover, when Ta time passes, if it is as calculation, both battery modules A and B will be fully charged, and charge will be complete | finished.

  In the second example, the voltage value of each set of battery modules 11 is detected by the module voltage detector 43 during charging. Then, based on the charging current value of the battery module 11 with the least degradation as a reference, the voltage value of the battery module 11 with the least degradation matches the voltage value of the battery module 11 with the least degradation. The charging current value of the battery module 11 of the set is determined according to the deterioration state. The charging current value is output to the power controller 23 of the corresponding charging device 2 via each set of module controllers 45. Then, the power supply controller 23 outputs a control signal so that the determined charging current value flows to the direct current power supply 21. When the voltage value detected from the module voltage detector 43 reaches the full charge voltage value, each set of module controllers 45 that captures the fact outputs a charge stop signal to the corresponding power supply controller 23 of the charging device 2 and simultaneously. Stop charging.

  The determination of the charging current value is performed as follows, for example. On the same premise as in the first example, for example, the battery module A is charged continuously by the charging device A at the current value Ia, the voltage value of the battery module A is Va, and the battery module B is charged by the charging device. B is continuously charged with the current value Ib, and the voltage value of the battery module B is Vb. Since the battery module with large deterioration has a large internal resistance, when charging with the maximum current value Im = Ia = Ib, Va <Vb is satisfied, so that Ib is made smaller than Ia and continuously charged so that Va = Vb. If it does so, deterioration of the battery module B can be suppressed rather than before. And if Va becomes a predetermined value, since both the battery modules are fully charged, charging is stopped.

  The present invention is not limited to the above examples. For example, the large secondary battery 1 may be one in which three or more battery modules 11 are connected in parallel. Further, the number of battery modules 11 connected in parallel and the number of charging devices 2 are not necessarily the same. For example, the number of battery modules 11 connected in parallel may be four and the number of charging devices 2 may be two, and in this case, the four battery modules 11 connected in parallel may be separated into two sets. .

1 large secondary battery 2 charging device 3 switching unit 4 charging control unit 5 load 6 system disconnection unit 11 battery module 12 cell 13 cell group 21 DC current power source 22 internal switch 23 power supply controller 41 module monitoring device 42 cell voltage detector 43 module Voltage detector 44 Current detector 45 Module controller

Claims (4)

In the charging method of a large-sized secondary battery in which a large-sized secondary battery (1) in which a plurality of battery modules (11) composed of a large number of cells (12) are connected in parallel is charged by a charging device (2).
The large secondary battery (1) shall be charged with a plurality of charging devices (2),
The parallel connection between at least one battery module (11) and another battery module (11) is disconnected to divide the large secondary battery (1) into a plurality of sets, and each set of battery modules (11) is charged differently. Charge individually with device (2) ,
The battery module (11) of each set is judged to be deteriorated and the capacity is calculated. The charging time of the battery module (11) of the set with low deterioration is calculated from the capacity and the charging current value. In order to match the charging times of the battery modules (11) of the other group, the charging current value of the other battery module (11) is determined from the capacity and the charging time and charged. How to charge the next battery. In the charging method of a large-sized secondary battery in which a large-sized secondary battery (1) in which a plurality of battery modules (11) composed of a large number of cells (12) are connected in parallel is charged by a charging device (2).
The large secondary battery (1) shall be charged with a plurality of charging devices (2),
The parallel connection between at least one battery module (11) and another battery module (11) is disconnected to divide the large secondary battery (1) into a plurality of sets, and each set of battery modules (11) is charged differently. Charge individually with device (2) ,
The deterioration state is determined for each group of battery modules (11), and the charging time and voltage value of the other battery module (11) are made to coincide with the charging time and voltage value of the battery module (11) with less deterioration. As described above, the large secondary battery is characterized in that the charging current value of the other battery module (11) is determined and charged with reference to the charging current value of the battery module (11) of the set with less deterioration. Charging method. A large secondary battery (1) in which a plurality of battery modules (11) composed of a large number of cells (12) are connected in parallel;
An opening / closing part (3) for separating parallel connection between at least one battery module (11) and another battery module (11) to divide the large secondary battery (1) into a plurality of sets;
A plurality of charging devices (2) capable of separately charging the battery modules (11) grouped into one set and the other set with the opening / closing part (3) as a boundary;
A charge control unit that opens and closes the opening / closing unit (3), determines the deterioration state of each battery module (11) from the deterioration state of the cell (12), and determines the charging condition of each battery module (11). (4) and only contains,
The charge control unit (4) determines the deterioration state and calculates the capacity of each battery module (11) of each set, and calculates the charging time of the battery module (11) of the lower deterioration set from the capacity and the charging current value. The charging current value of the other battery module (11) is determined from the capacity and the charging time so that the charging time of the other battery module (11) matches the calculated charging time. A charging system for a large-sized secondary battery. A large secondary battery (1) in which a plurality of battery modules (11) composed of a large number of cells (12) are connected in parallel;
An opening / closing part (3) for separating parallel connection between at least one battery module (11) and another battery module (11) to divide the large secondary battery (1) into a plurality of sets;
A plurality of charging devices (2) capable of separately charging the battery modules (11) grouped into one set and the other set with the opening / closing part (3) as a boundary;
A charge control unit that opens and closes the opening / closing unit (3), determines the deterioration state of each battery module (11) from the deterioration state of the cell (12), and determines the charging condition of each battery module (11). (4) and only contains,
The charging control unit (4) determines the deterioration state of each set of battery modules (11), and determines the charging time and voltage value of the battery modules (11) of the set with less deterioration of the other sets of battery modules (11). Based on the charging current value of the battery module (11) with a small deterioration so as to match the charging time with the voltage value, the charging current value of the other battery module (11) is determined and charged. A large-sized secondary battery charging system.

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