JP3496360B2 - Battery charging control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery pack charge control device configured by connecting a plurality of batteries in series.

[0002]

2. Description of the Related Art An assembled battery in which a plurality of batteries are connected in series is used to supply high voltage electric power to a motor of an electric vehicle or the like. A charging control device as shown in FIG. 6 for charging this assembled battery is known. In FIG. 6, the battery pack 1 has n single cells 11 to 1n connected in series,
When driving the motor, high-voltage DC power is supplied to the inverter 6. The inverter 6 converts DC power into AC power and drives the AC motor 7. On the other hand, when the assembled battery 1 is charged, charging power is supplied from the charger 2 to the assembled battery 1 via the switch 3. An overvoltage detection circuit 4 and a bypass circuit 5 are connected in parallel to each of the unit cells 11 to 1n,
When one of the unit cells is fully charged and its terminal voltage (hereinafter referred to as cell voltage) Vc reaches a predetermined overvoltage level, the corresponding overvoltage detection circuit 4 operates to activate the bypass circuit 5, The charging current of the single cell is bypassed by the bypass circuit 5, and a constant voltage is clamped so that the cell voltage Vc does not exceed the overvoltage level.

FIG. 7 shows an example of the overvoltage detection circuit 4. The overvoltage level of the overvoltage level generation circuit 8 including the resistor R1 and the Zener diode D1 and the detected value of the cell voltage Vc divided by the resistors R2 and R3 are compared by the comparator O.
If the detected value of the cell voltage Vc exceeds the overvoltage level as compared with P1, the operation command (Hi level signal) of the bypass circuit 5 is output. Further, FIG. 8 shows an example of the bypass circuit 5. When a Hi level operation command signal is supplied from the overvoltage detection circuit 4 to the operational amplifier OP2, the operational amplifier O2
The output of P2 is inverted and the transistor TR1 becomes conductive, so that the charging current flowing in the corresponding single cell is transferred to the transistor TR.
1 and through resistor R6. The bypass current flowing through the resistor R6 is detected by the operational amplifier OP3, and a voltage proportional to the bypass current is output from the operational amplifier OP3. The output voltage of the operational amplifier OP3 is the operational amplifier OP.
4 compares with the reference voltage set by R9 and D2, and when the output voltage of the operational amplifier OP3 exceeds the reference voltage, the operational amplifier OP4 outputs the bypass saturation detection signal. Here, the reference voltage of the operational amplifier OP4 is a limit bypass current at which the bypass circuit 5 cannot clamp the cell voltage Vc to a constant voltage (hereinafter, this state is referred to as bypass saturation, and the current at that time is referred to as bypass saturation current). The voltage is equivalent to (call). That is, the bypass circuit 5
When the current bypassing is saturated, a bypass saturation signal is output.

[0004]

By the way, each of the unit cells 11 to 1n forming the assembled battery 1 has the property that the cell voltage Vc increases or decreases in proportion to the charging capacity. When the charging capacity increases, the cell voltage Vc changes. To rise. In addition, each single cell 11 to 1n
Since each has an internal resistance r, the cell voltage Vc increases by a voltage drop IB · r due to the charging current IB during charging. Therefore, a large charging current IB up to near full charge
When the battery is charged at 1, the voltage drop IB · r becomes large and the cell voltage Vc rises. As a result, the cell voltage Vc exceeds the overvoltage level, the bypass circuit 5 is activated by the overvoltage detection circuit 4, and the charging current is bypassed although the single cell is not sufficiently charged. In order to avoid such a problem, normally, when charging the assembled battery 1, the current is controlled so that the charging current decreases when the battery pack 1 is near full charge, and the voltage drop IB · r due to the internal resistance r is reduced. It should be ensured that each single cell is almost fully charged.

However, for example, in an electric vehicle or the like, the on-vehicle electric equipment is used even while the assembled battery 1 is being charged, so that the charger 2 supplies the charging current IB to the assembled battery 1 and
It is necessary to supply the load current IL to the on-vehicle electrical equipment as well.
However, since the load current IL varies depending on the electric equipment used, if the charging current IB is reduced near the full charge, the load current IL becomes relatively large, and the charging current IB varies with the variation of the load current IL. It fluctuates irregularly. As a result, the single-cell bypass circuit operates abruptly and the charging current IB decreases quickly, which causes a problem that the charging time increases or the charging becomes insufficient.

An object of the present invention is to keep the charging current constant even when the load current flowing to the electric device changes during charging, and to keep the charging current small even when the step width of multi-stage constant current charging is small. An object of the present invention is to provide a charge control device for a battery pack that completely charges each single cell of the battery pack.

[0007]

[Means for Solving the Problems]

(1) In order to achieve the above object, the invention of claim 1 provides an assembled battery in which a plurality of unit cells are connected in series, a charger for charging the assembled battery, and each unit of the assembled battery. A plurality of bypass circuits that are connected in parallel to the cells and that bypass the charging current flowing through the single cells when the voltage across the single cells reaches a predetermined voltage; current detection means that detects the charging current IB of the assembled battery; A current control circuit for detecting the saturation of any one of the currents in the bypass circuit and transmitting a preset current reduction value IS to the charger, and a charging current target value IB ^* of the assembled battery are set. Then, the deviation Δ between the target value IB ^* and the charging current IB detected by the current detecting means.
A current correction circuit for transmitting IB to the charger, wherein the charger reduces the output current by the current reduction value IS when receiving the current reduction value IS from the current control circuit, and deviates from the current correction circuit. When ΔIB is received, the output current is corrected by the deviation ΔIB. In an assembled battery in which a plurality of single cells are connected in series, the charging current is bypassed by a bypass circuit when the voltage across one of the single cells reaches a predetermined voltage, and each time the bypass current is saturated, a preset current is set. The reduced value IS is sent to the charger, and the current reduced value IS
The charger that has received the signal reduces the output current by the current reduction value Is. Further, the charging current IB of the battery pack is detected, the deviation ΔIB between the charging current target value IB ^* and the charging current detection value IB is transmitted to the charger, and the charger receiving the deviation ΔIB corrects the output current by the deviation ΔIB. To do. (2) The invention according to claim 2 is an assembled battery in which a plurality of single cells are connected in series, a charger for charging the assembled battery, and a single battery connected in parallel to each single cell of the assembled battery. Any one of a plurality of bypass circuits for bypassing the charging current flowing in the single cell when the voltage across the cell reaches a predetermined voltage, a current detecting means for detecting the charging current IB of the assembled battery, and any one of the plurality of bypass circuits. A current control circuit that detects that the current of the battery is saturated, reduces a preset current reduction value Is from the output current command value IC ^{* of the} charger and transmits the current reduction value Is to the charger, and charging of the assembled battery. The current target value IB ^* is set, and the output current command value IC ^* of the charger is corrected by the deviation ΔIB between the target value IB ^* and the charging current IB detected by the current detecting means and transmitted to the charger. And a current correction circuit, wherein the charger is The output current is controlled according to the output current command value IC ^* received from the current control circuit and the current correction circuit. In an assembled battery in which multiple unit cells are connected in series, the output current of the charger is changed each time the voltage across one of the unit cells reaches a specified voltage and the bypass circuit bypasses the charging current, and the bypass current is saturated. A preset current reduction value Is is reduced from the command value IC ^* and transmitted to the charger. Further, the charging current IB of the battery pack is detected, the output current command value IC ^* is corrected by the deviation ΔIB between the charging current target value IB ^* and the charging current detection value IB, and the correction result is transmitted to the charger. The charger that received the output current command value IC ^*
The output current is controlled so that the output current becomes the command value IC ^* .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment will be described by taking an assembled battery mounted on an electric vehicle as an example. FIG. 1 is a block diagram showing the configuration of one embodiment. n single cells 21a-2
1n are connected in series to form an assembled battery 21, and each single cell 2
Overvoltage detection circuits 22a-22n and bypass circuits 23a-23n are connected in parallel to 1a-21n. These overvoltage detection circuits 22a-22n and bypass circuits 23a-
The circuits shown in FIG. 7 and FIG. 8 described above can be used for the respective 23n, and when any one of the unit cells is fully charged and the cell voltage Vc reaches a predetermined overvoltage level, the corresponding overvoltage is generated. The detection circuits (22a-22n) operate to activate the bypass circuits (23a-23n), bypass the charging current of the single cell, and perform constant voltage clamping. The electric device 24 is various electric components of an electric vehicle, and normally, power is supplied to these electric components from the assembled battery 21 via a DC-DC converter. The inverter and the motor connected to the assembled battery 21 are not directly related to the present invention, and therefore illustration and description thereof are omitted. The current sensor 25 detects the charging current IB of the assembled battery 1 and outputs it to the controller 26. The controller 26 is composed of a microcomputer and its peripheral components, and executes a control program described later to control charging of the assembled battery 21. The charger 27 is connected to the assembled battery 21 of the electric vehicle and the electric device 24 via the connectors 28a and 28b, charges the assembled battery 21 and supplies electric power to the electric device 24 used during charging. Further, the controller 26 and the charger 27 can communicate with each other via the connector 28c, and various kinds of information can be transmitted and received.

The main symbols used in this embodiment are shown in Table 1.

[Table 1] In Table 1, IC is an output current of the charger 27 and is divided into a load current IL of the electric device 24 used during charging and a charging current IB of the assembled battery 21. The load current IL
And the charging current IB are divided in proportion to the circuit resistance of the electric device 24 and the internal resistance of the assembled battery 21. Further, during charging, the load current IL of the electric device 24 changes as described above. IC ^* is a charger output current command value sent from the controller 26 to the charger 27. The charging current IB of the assembled battery 21 is detected by the current sensor 25. IB ^* is a battery pack 2
It is a target value of the charging current of 1 and is set by the controller 26. ΔIB is a deviation (= IB ^* -IB) between the target value IB ^* of the charging current and the detection current IB of the sensor 25. Other symbols will be described later.

FIG. 2 shows the charging power P (a), the cell voltage Vc (b) and the charging current IB at the time of charging in one embodiment.
The change of (c) is shown. In this embodiment, until the cell voltage of any of the unit cells (21a to 21n) reaches a predetermined overvoltage level (t0 to t2), the constant power mode (hereinafter,
Charging is performed in the CP mode), and then (t2)
Charges in a constant current mode (hereinafter referred to as CC mode). Also, if charging is suddenly started in CP mode, an excessive voltage may be applied to the assembled battery 21,
After charging is started, the charging power P is increased by a step value PS at predetermined time intervals, and when the maximum allowable value Pmax is reached, Pma
Charging in CP mode at constant x (startup mode,
t0 to t1). In addition, in this embodiment, an example in which the charging power is gradually increased in the startup mode after the start of charging is shown, but the charging method in the startup mode is not limited to this embodiment. In CC mode, one of the single cells (21a-21
In n), the cell voltage reaches a predetermined overvoltage level, bypass is performed, and each time the bypass is saturated (t3, t4, t
5, t6, ...) And the charging current target value IB ^* is reduced by the step value IS. Then, when the target charging current value IB ^* becomes smaller than the charging end current Imin, the charging is ended.

3 and 4 are flowcharts showing the charging process of the controller 26. The operation of the embodiment will be described with reference to this flowchart. The controller 26
When the charger 27 is connected to the electric vehicle and a charging switch (not shown) is turned on, the processing shown in FIGS. 3 and 4 is started.
In step 1, the charging power command value P ^* in the CP mode is transmitted to the charger 27, and in the following step 2, a predetermined time is waited. Here, the charger 2 waits for a predetermined time.
This is for performing the subsequent processing in consideration of the control response from when the command value 7 receives the command value P ^* to when the charging power is actually changed. In step 3, it is determined whether or not the charging current IB exceeds the allowable maximum value Imax. If IB> Imax, the process proceeds to step 21, and a charging stop command is output to the charger 27 to end the charging. This Imax is set to a value that can prevent an excessive current from flowing in the circuit due to a short circuit in the circuit or a charger failure. Next, at step 4, it is judged whether or not the charging time t after the start of charging exceeds the allowable time Tmax. If t> Tmax, the routine proceeds to step 21, where the charger 2
A charge stop command is output to 7 to end charging.

When the charging current IB and the charging time t do not exceed the allowable values, the routine proceeds to step 5, where it is determined whether or not the bypass operation is performed in any of the unit cells (21a to 21n), that is, the CP mode is set. It is determined whether to end.
When there is no bypass saturation and the CP mode is not ended, the routine proceeds to step 6, where the step value PS is added to the charging power command value P ^* . In the following step 7, it is determined whether or not the charging power command value P ^* exceeds the allowable maximum value Pmax. If P ^* > Pmax, the process proceeds to step 8 to set the command value P ^* to the allowable maximum value Pmax. After that, the process returns to step 1, the updated charging power command value P ^* is sent to the charger 27, and the above-described processing is repeated.

In CP mode, any single cell (2
When bypass saturation occurs in 1a to 21n), the mode is switched to CC mode charging. In step 11, the current sensor 25 detects the charging current IB0 at the time of switching from the CP mode to the CC mode, and the charging current IB0 is used to determine the step value IS.
The charging current target value IB ^* is set to the current obtained by subtracting. Here, the charging current IBO may be an average value for a predetermined time immediately after switching from the CP mode to the CC mode. In step 12, the charging current step value Is is transmitted to the charger 27. When the charger 27 receives the charging current step value IS, the charger 27 reduces the output current IC by the step value IS.

In step 13, it is judged whether the charging current command value IB ^* is smaller than the charging end current Imin,
If IB ^* <Imin, the process proceeds to step 21 and the charger 27
A charge stop command is output to and charging is completed. IB ^* ≧ Imi
When the answer is n, the process proceeds to step 14, and as described above, the charger 2
Wait a predetermined time to compensate for the control response of 7. Next, in step 15, the charging current deviation ΔIB (= IB ^* −IB)
Is calculated. In the following step 16,

## EQU1 ## It is determined whether or not the state of | ΔIB | ≧ I1 has continued for a predetermined time T1 or longer. Here, a reference value for determining whether or not the charging capacity of the charger 27 matches the charging capacity of the assembled battery 21 is set to the predetermined value I1 of the deviation ΔIB and the predetermined time T1. When the state of Expression 1 continues for a predetermined time T1 or more, the routine proceeds to step 21, where a charging stop command is output to the charger 27 and charging is terminated. When the state of Expression 1 is less than the predetermined time T1, step 1
7, the process determines whether or not the bypass saturation has occurred in any of the unit cells (21a to 21n), and if there is bypass saturation, the process proceeds to step 19. In step 19, the charging current target value IB ^*
Is reduced by the step value IS to update the target value IB ^*, and the process returns to step 12 and the charging current step value I is supplied to the charger 27.
Send S. Charger 27 which received the charging current step value IS
Reduces the output current IC by the step value IS. That is, in the CC mode, the charger output current IC is reduced by the step value IS each time there is bypass saturation in any single cell. Hereinafter, the above process is repeated.

When there is no bypass saturation in step 17, the process proceeds to step 18,

[Equation 2] It is determined whether or not the condition of | ΔIB | ≧ I2 has continued for a predetermined time T2 or more. Here, a reference value for determining whether or not to correct the charger output current IC by the variation of the load current IL is set to the predetermined value I2 of the deviation ΔIB and the predetermined time T2. When the state of Expression 2 continues for the predetermined time T2 or more, the process proceeds to step 20, and ΔIB is transmitted to the charger 27. As described above, when the load current IL of the electric device 24 fluctuates during charging, the charging current IB fluctuates, and the deviation ΔIB from the target value IB ^* increases or decreases. In order to compensate the charging current deviation ΔIB due to the fluctuation of the load current IL, the charger 27 corrects the output current IC by the deviation ΔIB sent from the controller 26. When the state of Expression 2 is less than the predetermined time T2, the process returns to step 17 and the bypass operation is confirmed again.

As described above, the step value IS of the charging current is sent to the charger whenever the bypass saturation occurs in any one of the cells in the CC mode, and the output current IC is reduced by the step value IS by the charger to obtain the charging current. IB is the charging end current I
Charge until it becomes smaller than min. Further, the charging current IB is monitored by the current sensor 25, and when the deviation ΔIB between the charging current target value IB ^* and the charging current detection value IB becomes large, the deviation ΔIB is sent to the charger and the charger output current IC is deviated by the deviation ΔIB.
Therefore, even if the load current IL flowing to the electric device 24 fluctuates during charging, the fluctuation of the charging current IB can be suppressed to a constant level, and all single cells can be charged almost completely.

-Modification of the above-mentioned embodiment-In the above-mentioned embodiment, the step value IS of the charging current is sent to the charger and the output current IC is changed by the step value whenever the bypass saturation occurs in any single cell in the CC mode. I tried to reduce only IS. Further, the charging current IB is monitored by the current sensor 25, and when the deviation ΔIB between the charging current target value IB ^* and the charging current detection value IB becomes large, the deviation ΔIB is sent to the charger.
Then, the output current IC is corrected by the deviation ΔIB by the charger. That is, instead of instructing the output current value to the charger, the charging current IB0 at the time of switching from the CP mode to the CC mode is used as the initial value, and the increment / decrement from the initial value IB0 is instructed. . In this modification, an example is shown in which the output current value itself is instructed to the charger. The configuration of this modification is the same as the configuration of the above-described embodiment shown in FIG.

FIG. 5 is a flowchart showing a modification of the charging process. The processing in the start mode and the CP mode is the same as that in the above-described embodiment shown in FIG. 3, and the processing in the CC mode will be mainly described. CP mode to C
After shifting to C mode, in step 30, the current sensor 2
5, the charging current IB0 at the time of switching from the CP mode to the CC mode is detected, and a current obtained by subtracting the step value IS from the charging current IB0 is set as the charging current target value IB ^* . Here, the charging current IBO may be an average value for a predetermined time immediately after switching from the CP mode to the CC mode.
In the following step 31, it is judged whether or not the charging current command value IB ^* is smaller than the charging end current Imin, and IB ^* <Im.
If it is in, the process proceeds to step 41, where a charging stop command is output to the charger 27 to end the charging. When IB ^* ≧ Imin, the routine proceeds to step 32, where the charging current target value IB ^* is set to the charger output current command value IC ^*, and at the following step 33, the output current command value IC ^* is transmitted to the charger 27. The charger 27 controls the output current so that the output current IC becomes the command value IC ^* from the controller 26. In step 34, charger 2
Wait a predetermined time to compensate for the control response of 7.

In step 35, the charging current deviation ΔIB is calculated. In a succeeding step 36, it is determined whether or not the state of the above mathematical expression 1 has continued for a predetermined time T1 or more. Where the deviation ΔIB
The predetermined value I1 and the predetermined time T1 are set to reference values for determining whether or not the charging capacity of the charger 27 matches the charging capacity of the assembled battery 21. The state of Expression 1 is the predetermined time T
When it continues for 1 or more, the routine proceeds to step 41, where a charging stop command is output to the charger 27 to end the charging. When the state of Expression 1 is less than the predetermined time T1, the routine proceeds to step 37, where it is determined whether bypass saturation has occurred in any of the unit cells (21a to 21n), and if there is bypass saturation, the routine proceeds to step 39. In step 39, the charging current target value IB ^* is reduced by the step value IS to update the target value IB ^*, and the process returns to step 31 to repeat the above processing. That is, the updated charging current target value IB ^* set to the charger output current command value IC ^*, and sends the charger output current command value IC ^* to the charger 27. The charger 27 controls the output current IC so that the output current IC becomes the updated command value IC ^* . That is, in the CC mode, the charger output current IC is reduced by the step value IS each time there is bypass saturation in any single cell. Hereinafter, the above process is repeated.

When there is no bypass saturation at step 37, the routine proceeds to step 38, where it is judged if the state of the equation 2 has continued for a predetermined time T2 or more. Here, a reference value for determining whether or not to correct the charger output current IC by the variation of the load current IL is set to the predetermined value I2 of the deviation ΔIB and the predetermined time T2. When the state of Expression 2 continues for the predetermined time T2 or more, the routine proceeds to step 40, where the charger output current command value IC ^*
Is corrected by adding the charging current deviation ΔIB to step 33.
Then, the corrected output current command value IC ^* is sent to the charger 27. As described above, when the load current IL of the electric device 24 fluctuates during charging, the charging current IB fluctuates, and the deviation ΔIB from the target value IB ^* increases or decreases. In order to compensate the charging current deviation ΔIB due to the variation of the load current IL, the charger 27 controls the output current so that the output current IC becomes the corrected command value IC. When the state of Expression 2 is less than the predetermined time T2, the process returns to step 37 and the bypass operation is confirmed again.

In this way, every time there is bypass saturation in any single cell in the CC mode, the charger output current command value IC ^* is reduced by the step value IS to instruct the charger, and the charging current IB ends charging. Charging is performed until it becomes smaller than the current Imin, and the charging current IB is measured by the current sensor 2
5, the charging current target value IB ^* and the charging current detection value IB
When the deviation ΔIB from the electric current becomes large, the charger output current command value IC ^* is corrected by the deviation ΔIB to instruct the charger, so that the load current I flowing to the electric device 24 during charging is increased.
Even if L changes, the change in charging current IB can be suppressed to a constant level, and all single cells can be charged almost completely.

In the configuration of the above embodiment, the assembled battery 21 is an assembled battery, the single cells 21a to 21n are single cells, the overvoltage detection circuits 22a to 22n and the bypass circuit 23a.
23n form a bypass circuit, the current sensor 25 forms a current detecting means, the controller 26 forms a current control circuit and a current correction circuit, and the charger 27 forms a charger. In the above-described embodiment, the example in which the charging current flowing in the single cell is bypassed when the voltage across the single cell reaches the predetermined voltage has been shown. However, as shown by the broken line in FIG. 1, the charging current flowing in the single cell is bypassed. Alternatively, the charging current target value in the CC mode may be lowered when the voltage across the unit cell reaches a predetermined voltage. However, in this case, since the charge amount cannot be changed for each single cell, it is necessary that the individual difference (variation in voltage) between cells is as small as possible.

[0023]

【The invention's effect】

(1) As described above, according to the invention of claim 1,
In an assembled battery in which a plurality of single cells are connected in series, the charging current is bypassed by a bypass circuit when the voltage across one of the single cells reaches a predetermined voltage, and each time the bypass current is saturated, a preset current is set. The reduction value IS is transmitted to the charger, and the charger receiving the current reduction value IS reduces the output current by the current reduction value IS. Further, the charging current IB of the assembled battery is detected, and the deviation ΔIB between the charging current target value IB ^* and the charging current detection value IB is transmitted to the charger, and the deviation ΔI
The charger that receives B corrects the output current by the deviation ΔIB. As a result, even if the load current flowing to the electric device changes during charging, the charging current can be kept constant and each unit cell can be charged almost completely. (2) According to the invention of claim 2, in the assembled battery in which a plurality of unit cells are connected in series, the voltage across each of the unit cells reaches a predetermined voltage, and the charging current is bypassed by the bypass circuit. Each time the current is saturated, a preset current reduction value I from the charger output current command value IC ^{* is} set.
While reducing S and transmitting it to the charger, the charging current IB of the assembled battery is detected, and the output current command value IC ^* is corrected by the deviation ΔIB between the charging current target value IB ^* and the charging current detection value IB to perform charging. I sent it to the vessel. The charger that receives the output current command value IC ^*, the output current is to control the output current so that the command value IC ^*. This allows
Even if the load current flowing to the electric device changes during charging, the charging current can be kept constant, and each single cell can be charged almost completely.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment.

FIG. 2 is a charging power P and a cell voltage V during charging according to an embodiment.
The figure which shows the change of C and charging current IB.

FIG. 3 is a flowchart showing a charging process according to an embodiment.

FIG. 4 is a flowchart showing a charging process according to the embodiment, following FIG.

FIG. 5 is a flowchart showing a modified example of the charging process.

FIG. 6 is a diagram showing a configuration of a conventional battery pack charge control device.

FIG. 7 is a diagram showing an example of an overvoltage detection circuit.

FIG. 8 is a diagram showing an example of a bypass circuit.

[Explanation of symbols]

21 batteries 21a-21n single cell 22a-22n Overvoltage detection circuit 23a-23n bypass circuit 24 electrical equipment 25 current sensor 26 Controller 27 charger

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02J 7/00-7/12 H02J 7/34-7/36 B60L 1/00-3/12 B60L 7 / 00-13/00 B60L 15/00-15/42

Claims (2)

(57) [Claims] 1. An assembled battery in which a plurality of unit cells are connected in series, a charger for charging the assembled battery, and a battery connected to each unit cell of the assembled battery in parallel and having a voltage across both ends of the unit cell. When a predetermined voltage is reached, a plurality of bypass circuits that bypass the charging current flowing in the single cell, a current detection unit that detects the charging current IB of the assembled battery, and one of the plurality of bypass circuits is saturated. And a current control circuit that detects the fact that it sends a preset current reduction value Is to the charger, and a charging current target value IB ^* of the assembled battery, and sets a target value IB ^*.
And a current correction circuit that transmits a deviation ΔIB from the charging current IB detected by the current detection means to the charger, the charger outputs the output current when the current reduction value IS is received from the current control circuit. A charging control device for an assembled battery, which reduces the current reduction value IS and corrects the output current by the deviation ΔIB when the deviation ΔIB is received from the current correction circuit. 2. An assembled battery in which a plurality of unit cells are connected in series, a charger for charging the assembled battery, and a single cell connected in parallel to each unit cell of the assembled battery, wherein When a predetermined voltage is reached, a plurality of bypass circuits that bypass the charging current flowing in the single cell, a current detection unit that detects the charging current IB of the assembled battery, and one of the plurality of bypass circuits is saturated. Of the output current command value IC ^{* of the} charger, a current control circuit for reducing a preset current reduction value IS and transmitting the current to the charger, and a charging current target value IB ^{* of the} battery pack ^. And set the target value IB ^*
And a current correction circuit that corrects the output current command value IC ^* of the charger based on the deviation ΔIB from the charging current IB detected by the current detection means and sends the corrected output current command value IC ^* to the charger. An assembled battery charging control device for controlling an output current according to an output current command value IC ^* received from a current control circuit and the current correction circuit.