JP2001186686A - Charging device, and method for charging battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely charge a plurality of battery cells to a target voltage by applying to the adjustment device of a battery unit being mounted to, for example, an electric car and effectively preventing the overcharging of the battery cell. SOLUTION: After a charge current is increased in steps successively within a range where the battery voltage of a secondary battery cell does not exceed a specific voltage, the charge current is decreased in steps successively, thus completing charging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device and a method of charging a battery, and can be applied to, for example, a battery unit adjusting device mounted on an electric vehicle. The present invention increases the charging current in a stepwise manner within a range in which the battery voltage of the secondary battery cell does not exceed a predetermined voltage, and then gradually decreases the charging current in a stepwise manner to terminate charging. An object of the present invention is to effectively prevent overcharging of a cell and reliably charge a plurality of battery cells to a target voltage.

[0002]

2. Description of the Related Art Conventionally, in an electric vehicle, a battery unit is formed by integrating a predetermined number of battery cells, and a large number of battery cells are mounted by mounting a plurality of such battery units. . As a result, the electric vehicle can secure sufficient power by repeating charging and discharging of these many battery cells, and can easily manage many battery cells by managing the battery cells in units of battery units. Has been made.

[0003]

In an electric vehicle, the performance of the battery cell itself may be degraded when the vehicle is used outdoors due to severe temperature changes. Need to install a new battery unit.

[0004] In this case, in the electric vehicle, since the electric power according to the use condition is already stored in each battery unit, simply replacing the battery unit often results in replacement of the replaced battery unit with another battery unit. A difference occurs in the power stored between the battery unit and the battery unit. When a difference occurs in the power stored between the battery units as described above, after all, when viewed as a whole,
The capacity of the battery will be reduced. In other words, during charging, the overall charge is limited by the battery unit having a large remaining amount, whereas during discharging, the discharging is limited by a battery unit having a small remaining amount.

Therefore, when replacing the battery unit in this manner, it is considered necessary to set the power of the newly attached battery unit to be substantially equal to the power stored in the other battery units.

[0006] In a battery such as a lithium ion secondary battery, the battery voltage, which is a terminal voltage, changes according to the remaining amount, so that the power of a newly attached battery unit is stored in another battery unit. It is considered that the work of setting the power to be substantially equal to the power can be performed by adjusting the remaining amount of the newly installed battery unit so that the battery voltage of the other battery units becomes equal to the battery voltage.

However, when such adjustment is performed by charging the battery unit, some battery cells may be overcharged. Incidentally, as one method of preventing such overcharging, a method of charging in battery cell units is conceivable. However, when a battery unit is configured by integrating a plurality of battery cells, the battery cells are It may be difficult to charge individually.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and a battery charger and a battery charger capable of effectively preventing overcharging of a battery cell and reliably charging a plurality of battery cells to a target voltage. It is intended to propose a charging method.

[0009]

In order to solve the above-mentioned problems, the invention according to claim 1 or 3 is applied to a charging device or a method of charging a battery, and the battery voltage of any of the secondary battery cells is reduced. Until the voltage reaches a predetermined voltage, the battery is charged by gradually increasing the charging current, and when the battery voltage of any of the secondary battery cells reaches the predetermined voltage, the charging current is gradually reduced in a stepwise manner. Charge.

[0010] If the battery voltage is charged by gradually increasing the charging current until the battery voltage of any of the secondary battery cells reaches the predetermined voltage, the battery voltage of the secondary battery cell will overshoot. However, it is possible not to exceed the predetermined voltage. As a result, when the battery voltage of any of the secondary battery cells reaches a predetermined voltage, the charging current is gradually reduced in a stepwise manner to charge the battery, so that the terminal voltage does not become excessively large, and the desired battery is reliably prevented. It can be charged to a voltage.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(1) Configuration of Embodiment FIG. 2 is a block diagram showing an adjusting device according to an embodiment of the present invention. This adjustment device 1 charges a battery unit 2 mounted on an electric vehicle. Here, the battery unit 2 is a unit in which a plurality of lithium ion secondary battery cells are connected in series and integrated, and is configured so that the battery voltages E1 to En of the respective battery cells can be externally measured. Used by mounting.

In the adjusting device 1, a charging power supply 3 supplies a charging current to the battery unit 2 under the control of a control circuit 4. The current detection circuit 6 detects the charging current Ic of the battery unit 2 and notifies the control circuit 4 of the detection result.

The control circuit 4 is a controller for controlling the operation of the entire adjusting device 1. When the operator instructs the start of the adjustment after the battery unit 2 is set, the adjustment is performed via a display device (not shown). Accepts setting of target voltage. Here, the voltage of the adjustment target is a battery voltage of another battery unit of the electric vehicle to which the battery unit 2 is mounted.

When the control circuit 4 receives the setting of the adjustment target, the control circuit 4 divides the voltage by the number of cells of the battery unit 2 to obtain the maximum set voltage Vcell of each battery cell.
MAX is detected. When the battery unit 2 is fully charged, the maximum set voltage VcellMAX is the full charge voltage of each battery cell.

When the setting of the adjustment target is received in this way, the control circuit 4 executes the processing procedure shown in FIG. 1 to start charging the battery unit 2. That is, the control circuit 4
After instructing the charging power source 3 to start charging with a predetermined charging start current, the process proceeds from step SP1 to step S
Moving to P2, it is determined whether or not the battery voltages E1 to En of the respective battery cells are normal. Here, when the battery voltages E1 to En of the battery cells exceed the full charge voltage,
Alternatively, when the battery voltage of one battery unit differs from the terminal voltage of another battery unit by a predetermined voltage or more, it is determined that there is an abnormality.

If a negative result is obtained here, the control circuit 4
Moves to step SP3, and ends this processing procedure.
On the other hand, if a positive result is obtained in step SP2, the control circuit 4 proceeds to step SP4 and waits for a predetermined time. Subsequently, the control circuit 4 proceeds to step SP5, determines whether or not the battery voltages E1 to En of any of the battery cells have reached the maximum set voltage VcellMAX. If a negative result is obtained here, the control circuit 4 proceeds to step SP6 to charge the battery. The charging power source 3 increases the current by a predetermined current value ΔI.
To instruct.

Subsequently, the control circuit 4 determines whether or not the charging current has reached a preset maximum charging current IcMAX. If a negative result is obtained here, the process returns to step SP4. As a result, the control circuit 4 sets the period T1 in FIG.
, The battery voltage E of any of the battery cells
Until 1 to En reach the maximum set voltage VcellMAX,
Alternatively, the processing procedure of steps SP4-SP5-SP6-SP7-SP4 is repeated until the charging current reaches the maximum charging current IcMAX, and the charging current is sequentially increased by a predetermined current value ΔI at the standby time interval set in step SP4. The battery unit 2 is charged while being increased.

As described above, when the charge current is sequentially increased and the battery voltages E1 to En of any of the battery cells reach the maximum set voltage VcellMAX, the control circuit 4
When a positive result is obtained in step SP5, the process moves from step SP5 to step SP8. Similarly, when the charging current reaches the maximum charging current IcMAX, a positive result is obtained in step SP7,
The control circuit 4 proceeds from step SP7 to step SP8.

Here, the control circuit 4 stops increasing the charging current. Subsequently, the control circuit 4 proceeds to step SP9,
It is determined whether or not the battery voltages E1 to En of any of the battery cells have reached the maximum set voltage VcellMAX. If a negative result is obtained here, the control circuit 4 repeats step SP9. As a result, the control circuit 4 determines that the battery voltages E1 to En of any of the battery cells have reached the maximum set voltage VcellM.
Until AX, the battery unit 2 is charged with a constant current value as indicated by a period T2 in FIG.

Thus, the control circuit 4 determines that the battery voltages E1 to En of any of the battery cells have reached the maximum set voltage Vce.
When the battery voltage reaches 11MAX or when the charging current reaches the maximum charging current IcMAX, the process proceeds to step SP9 via step SP8, so that the battery voltages E1 to En of any of the battery cells are set to the maximum value. Voltage Vc
If the process goes to step SP9 with the cell being set to “ellMAX”, without repeating step SP9,
Move to step SP10.

On the other hand, the charging current is equal to the maximum charging current Ic.
When the process proceeds to step SP9 as the maximum value, the process proceeds to step SP9 until the battery voltages E1 to En of any of the battery cells reach the maximum set voltage VcellMAX.
Step 9 is repeated, and the routine goes to Step SP10.

In step SP10, the control circuit 4 reduces the charging current Ic by a predetermined value ΔI.
The operation of the charging power supply 3 is controlled. Subsequently, the control circuit 4 proceeds to step SP11, determines whether or not the charging current Ic has reached the minimum charging current IcMIN. If a negative result is obtained here, the control circuit 4 returns to step SP9. That is, as shown in FIG. 3, in the battery cell, even if the lithium ion secondary battery cell is charged with a constant charging current, the battery voltage drops when the charging is stopped. This means that the target battery voltage has not been set. That is, a difference occurs in the remaining amount between the battery unit and another battery unit to be mounted.

Accordingly, the control circuit 4 determines that the battery voltages E1 to En of any of the battery cells have reached the maximum set voltage Vcell.
Even in the case of MAX, this step SP9-SP10-SP11-SP9 is performed without immediately stopping charging.
By repeating the processing procedure of FIG.
As shown by 3, the battery unit 2 is charged by sequentially reducing the charging current Ic.

Further, charging is performed in this manner, and charging current I
When c becomes the minimum charging current IcMIN, the control circuit 4
The process moves from step SP11 to step SP12. Here, the control circuit 4 controls the battery voltages E1 to E1 of any of the battery cells.
It is determined whether or not En has reached the maximum set voltage VcellMAX. If a negative result is obtained here, the control circuit 4 repeats step SP12.

On the other hand, if a positive result is obtained in step SP12, the control circuit 4 proceeds to step SP13
Then, after instructing the charging power source 3 to stop supplying the charging current, the process proceeds to step SP3 to end the processing procedure.

The control circuit 4 monitors the battery voltage of each battery cell simultaneously and in parallel in these series of processing procedures, and immediately stops charging if any of the battery voltages becomes abnormal.

(2) Operation of the Embodiment In the above configuration, in the adjusting device 1 (FIG. 2),
After the battery unit 2 mounted on the electric vehicle is mounted, the battery voltage of another battery unit of the electric vehicle is input to the control circuit 4 as a target voltage for adjustment, and the maximum voltage of each battery cell is calculated based on the target voltage. Set voltage Vc
ellMAX is calculated.

In the adjusting device 1 (FIGS. 1 and 3), after the supply of the charging current by the predetermined charging start current from the charging power source 3 is started from the charging power source 3, the battery voltages E1 to E1 of any of the battery cells are changed. En is the maximum set voltage Vcel
Until the charging current reaches the maximum charging current IcMAX or until the charging current reaches the maximum charging current IcMAX, the charging current is sequentially increased stepwise at predetermined time intervals and charged.

At this time, even when the battery voltage overshoots due to the follow-up control of the control system or the like, the battery unit 2 can gradually increase the maximum charging current in a stepwise manner at a constant time interval. Does not exceed the maximum set voltage VcellMAX, that is, reliably prevents overcharging, and allows a large amount of power to be charged in a short period of time, thereby shortening the time required for charging.

In this manner, when the charging current is increased stepwise and reaches the maximum charging current IcMAX before reaching the maximum set voltage VcellMAX, the battery unit 2 is charged by the maximum charging current IcMAX. When the battery voltages E1 to En of any of the battery cells reach the maximum set voltage VcellMAX, the charging current is reduced step by step, and charging ends.

Also, if any of the battery cells reaches the maximum set voltage VcellMAX before the charging current reaches the maximum charging current IcMAX, the charging current is similarly gradually reduced and charged.

At this time, since the charging current is sequentially reduced, the battery unit 2 is reliably charged so that the terminal voltage does not decrease even if the charging is stopped, that is, the battery voltage reaches the target battery voltage. . As a result, the battery is charged so that the difference in the remaining amount with the other battery units is sufficiently small, and the battery units can be mounted on an electric vehicle and used effectively.

(3) Effects of Embodiment According to the above configuration, the charging current is increased step by step within a range in which the battery voltage of the secondary battery cell does not exceed the predetermined voltage, and then the charging current is sequentially increased. By terminating the charging and terminating the charging, overcharging of the battery cells can be effectively prevented, and the plurality of battery cells can be reliably charged to the target voltage.

(4) Other Embodiments In the above-described embodiment, a case has been described in which a battery unit in which battery cells are connected in series is charged to have the same power as another battery unit. However, the present invention is not limited to this, and can be widely applied to the case where the battery unit is fully charged.

In the above-described embodiment, the case where the battery unit mounted on the electric vehicle is charged has been described. However, the present invention is not limited to this, and the present invention is widely applied to the case where the battery mounted on various devices is charged. Can be applied.

[0037]

As described above, according to the present invention, the charging current is sequentially increased stepwise within a range where the battery voltage of the secondary battery cell does not exceed the predetermined voltage, and then the charging current is sequentially increased stepwise. By terminating the charging by decreasing the charging, the overcharging of the battery cells can be effectively prevented, and the plurality of battery cells can be reliably charged to the target voltage.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a processing procedure of a control circuit in an adjustment device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an adjusting device to which the control circuit of FIG. 1 is applied;

FIG. 3 is a characteristic curve diagram for explaining the operation of the control circuit of FIG. 1;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 adjustment device 2 battery unit 3 charging power supply 4 control circuit 6 current detection circuit

Claims (4)

[Claims] 1. A charging device for charging a battery by a plurality of secondary battery cells, voltage detecting means for detecting a battery voltage of each of the secondary battery cells and outputting a voltage detection result, and charging the battery. A charging power supply that supplies a current, a current detecting unit that detects a charging current of the battery and outputs a current detection result, and a control unit that controls the charging power supply based on the voltage detection result and the current detection result. The control means, until the battery voltage of any of the secondary battery cells reaches a predetermined voltage, so as to gradually increase the charging current step by step, of any of the secondary battery cells The charging device according to claim 1, wherein the charging power source is controlled so that the charging current is gradually reduced when the battery voltage reaches a predetermined voltage. 2. The control means according to claim 1, wherein said charging current has reached a predetermined value even before said battery voltage of any of said secondary battery cells has reached a predetermined voltage. The charging device according to claim 1, wherein the charging power source is controlled so as to stop the increase. 3. A method for charging a battery using a plurality of secondary battery cells, wherein the charging current is sequentially increased stepwise until a battery voltage of any one of the secondary battery cells reaches a predetermined voltage. And charging the battery by gradually decreasing the charging current when the battery voltage of any of the secondary battery cells reaches a predetermined voltage. 4. An increase in the charging current is stopped when the charging current has reached a predetermined value even before the battery voltage of any of the secondary battery cells has reached the predetermined voltage. The method for charging a battery according to claim 3, wherein: