JPH0928042A - Device for controlling charging of battery assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for controlling charging of a battery assembly which can effectively eliminate the variable charging of each cell constituting the battery assembly while preventing overcharging and, at the same time, suppressing useless power consumption. SOLUTION: Voltage detecting circuit 3a-3n detect the terminal voltages of cells 1a-1n constituting a battery assembly 1 and a control circuit 4 sets the value of the by-pass current of each cell in accordance with the terminal voltage of each cell before starting the charging of the cells 1a-1n so that the charging current of the cell having the lowest initial voltage can become larger by reducing the by-pass current of the cell. Consequently, the amount of a useless current flowing to each by-pass circuit 2a-2n becomes smaller and the variation of each cell 1a-1n can be effectively eliminated in a period of time shorter than that of the prior art embodiment. Therefore, the useless power consumption and heat generating problem resulting from the electric currents flowing to the by-pass circuits can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling charging of a battery pack in which a plurality of secondary batteries are connected in series or in series and parallel.

[0002]

2. Description of the Related Art For example, as a power source for an electric vehicle, a plurality of secondary batteries (cells composed of a single battery or a block composed of a plurality of cells) are connected in series or series-parallel in an amount corresponding to a required capacity. The assembled battery is used. Such an assembled battery has a large number of batteries (for example, 10 cells in an electric vehicle).
Since about 0 to 250 cells are used, it is important to secure the reliability of the battery system. That is, if the function of any of the batteries forming the assembled battery is deteriorated due to overdischarge, overcharge, or the like, the function of the entire assembled battery is deteriorated. Further, in the case of such an assembled battery, the degree of decrease in discharge capacity (the amount of electricity that can be discharged) differs depending on each battery. For example, due to variations in manufacturing among batteries and uneven temperature distribution when used in assembled batteries, there are differences in the self-discharge amount and charge acceptance rate (charge / discharge efficiency). The degree of decrease differs for each battery. Therefore, DOD (depth of discharge:
The discharge capacity from 0% at 100% at full discharge and 0% at full charge varies among the batteries, which reduces the discharge capacity of the assembled battery. That is, at the time of discharging, a battery whose discharge capacity has become small is quickly discharged and becomes an over-discharged state, and this over-discharged battery becomes a load of other batteries, and all the batteries do not reach DOD 100%. The voltage drops to the end and the assembled battery ends the discharge.

On the other hand, during charging and discharging, DOD100
Batteries that did not reach% reached DOD0% first and the voltage rises, and charging ends. However, batteries that are over-discharged during discharging do not reach DOD0% and charging ends. The difference widens, and the difference in discharge capacity of each battery also widens. Therefore, when charging and discharging are repeated, the battery having a small discharge capacity is always insufficiently charged, and the variation becomes large, and the discharge capacity of the entire assembled battery decreases. As described above, in an assembled battery in which a plurality of secondary batteries are connected in series, there are problems that the discharge capacity and the DOD are varied, the discharge capacity of the entire assembled battery is reduced, and a particular battery is particularly deteriorated. There is also a possibility that over-discharge or over-charge may generate more heat than usual.

As a conventional example for dealing with the above problem, for example, there is one described in Japanese Patent Application Laid-Open No. 4-331425. In the first conventional example, a voltage detecting means is provided for each cell constituting the assembled battery, and the charging is stopped when the detected voltage becomes equal to or higher than the charge end voltage.

A second conventional example is Japanese Patent Laid-Open No. 61-61
There is one described in Japanese Patent Publication No. 206179. This is one in which Zener diodes are connected in parallel for each cell constituting the assembled battery 1 and the Zener voltage of these Zener diodes is set to the end-of-charge voltage of the cells (for example, about 4 V in the case of a lithium ion battery). Is. In this circuit, when charging progresses and the terminal voltage of the cell rises and it reaches the charge cutoff voltage, the Zener diode connected in parallel conducts and bypasses the charging current. Is not performed and the cell whose terminal voltage does not reach the end-of-charge voltage is continuously charged. Therefore, charging is performed until each cell is fully charged, and variation can be reduced.

Further, as a third conventional example, a bypass circuit and a voltage detecting means are provided in parallel for each cell constituting the assembled battery, and a cell in which the detected voltage becomes equal to or higher than the charge cutoff voltage is There is also a system in which the variation of the charge amount is eliminated by turning on the bypass circuit of the cell to bypass the charging current.

[0007]

However, the conventional example as described above has the following problems. That is, in the first conventional example, when a cell that has reached the end-of-charge voltage is generated, charging is stopped, so there is no risk of overcharging, but variations between cells cannot be eliminated. Further, in the second conventional example, since the charging current of the fully charged cell is bypassed,
Since the charging current of the cell which has been fully charged first flows unnecessarily through the Zener diode, the electric power at the time of charging is wasted, the charging efficiency is deteriorated, and problems such as heat generation occur. Particularly, in a system having a large number of cells of about 100 to 250 cells such as an electric vehicle, the wasteful power consumption and heat generation due to the wasteful power consumption cannot be ignored. Further, even in the case of providing a bypass circuit for each cell and performing precise control like the third conventional example, the control condition (bypass current value and ON voltage) of the bypass circuit is irrespective of the degree of variation in each cell. Was constant, the problems of wasted power consumption and heat generation due to the current flowing through the bypass circuit were the same as above, and the durability of the bypass circuit components was increased if the bypass circuit frequently operated due to variations. Also causes problems. As described above, in the related art, since the amount of electric power wasted in the bypass circuit due to the elimination of the variation is poor, the charging efficiency is poor and the problem of heat generation occurs, and the durability of the bypass circuit component is deteriorated. There was a problem of doing.

The present invention has been made in order to solve the problems of the prior art as described above, and the first object is to prevent the overcharge and effectively eliminate the variation and to waste the power. An object of the present invention is to provide a charge control device for an assembled battery that can suppress consumption. A second object is to provide an assembled battery charge control device capable of suppressing wasteful power consumption and preventing deterioration of durability of the bypass circuit.

[0009]

Means for Solving the Problems In order to achieve the above object, the present invention is configured as described in the claims. That is, in the invention according to claim 1, an assembled battery in which a plurality of secondary battery cells are connected in series or in series-parallel is connected in parallel for each of the cells or for each block composed of a plurality of cells. Detects the voltage of each cell before charging, or the voltage of a block composed of a plurality of cells, and a bypass means that is turned on when the voltage of the cell or the block is equal to or higher than a predetermined voltage during charging and bypasses the charging current. Then, detect the highest voltage of all the cells or blocks,
A control means for setting an operating condition for each bypass means based on the difference between the highest voltage and the voltage of each cell or block and controlling each bypass means in accordance therewith. The above configuration corresponds to, for example, the embodiment shown in FIG.
In the bypass circuits 2a to 2n, the control means corresponds to the voltage detection circuits 3a to 3n and the control circuit 4.

[0010] The invention described in claim 2 is the same as the claim 1.
As the configuration of the control means in, as the difference between the highest voltage and the voltage of each cell or block is larger, the bypass current value of the bypass circuit is set to a smaller value, and the current value to be passed through each bypass means is set accordingly. It is configured to control. The above configuration is described in, for example, FIG.
Corresponds to the embodiment shown in FIG. Further, the invention according to claim 3 is the configuration of the control means according to claim 1, wherein the greater the difference between the highest voltage and the voltage of each cell or block, the greater the predetermined voltage for turning on the bypass circuit. The value is set to a large value, and ON / OFF of each bypass means is controlled accordingly.
The above configuration corresponds to, for example, the embodiment shown in FIG. 3 described later.

Further, the invention according to claim 4 is an assembled battery in which a plurality of secondary battery cells are connected in series or series-parallel,
By-pass means, which is connected in parallel for each cell or for each block composed of a plurality of cells, is turned on when the voltage of the cell or the block is equal to or higher than a predetermined voltage during charging, and bypasses the charging current; When the voltage of each cell or the voltage of a block composed of a plurality of cells is detected and the variation of the voltage of all cells or blocks is within a predetermined range, the operation of the bypass means is stopped, and the variation is outside the predetermined range. And a control means for controlling the bypass means to perform a normal operation. The above configuration corresponds to, for example, the embodiment shown in FIG. 6 described later, and the bypass means and the control means are the voltage determination bypass circuits 21a to 21a of FIG.
21n and the control circuit 22.

[0012]

According to the first aspect of the present invention, the operating condition is set for each bypass means according to the voltage of each cell or each block before charging, and each bypass means is controlled accordingly. Specifically, as described in claim 2,
The value of the bypass current is set according to the terminal voltage of each cell before the start of charging, and the lower the initial voltage, the smaller the bypass current and the larger the charging current. Therefore, useless current flowing in the bypass circuit can be reduced, and variation in each cell can be effectively reduced in a shorter time than before. Therefore, it is possible to reduce unnecessary power consumption and heat generation due to the current flowing through the bypass circuit. Further, in claim 3, the value of the terminal voltage for operating the bypass circuit is set according to the terminal voltage of each cell before the start of charging, and the bypass circuit is turned on at a higher voltage for a cell having a lower initial voltage. Set. Therefore, useless current flowing in the bypass circuit can be reduced, and variation in each cell can be effectively reduced in a shorter time than before. Therefore, it is possible to reduce unnecessary power consumption and heat generation due to the current flowing through the bypass circuit.

Further, according to the invention of claim 4, when the variation in the terminal voltage of each cell is small and the necessity of operating the bypass circuit is low, the operation of the bypass circuit is prohibited. It is possible to suppress wasteful power consumption, prevent heat generation, and improve the durability of the bypass circuit constituent element. Further, when the variation in the terminal voltage of each cell is large, the bypass circuit is normally operated, so that the variation can be effectively reduced.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. 1 and 2 are views showing a first embodiment of the present invention. FIG. 1 is a circuit diagram of the entire configuration, and FIG. 2 is a circuit diagram of an example of the bypass circuit 2 in FIG. FIG.
In the above, 1 is an assembled battery, which is formed by connecting a plurality of cells 1a to 1n in series. In the embodiments described below, all cells are connected in series, but the cells may be connected in series and parallel. For example, it may be an assembled battery in which a plurality of blocks in which several cells are connected in parallel are connected in series. 2a to 2n are bypass circuits (details will be described later), which are connected in parallel for each cell.
3a to 3n are voltage detection circuits for detecting the voltage of each cell. In the case of the assembled battery in which the blocks are connected in series as described above, the bypass circuit and the voltage detection circuit are connected for each block. Reference numeral 4 denotes a control circuit, which is composed of, for example, a computer or the like, receives the voltage value from each of the voltage detection circuits 3a to 3n, and supplies the control signal S to each of the bypass circuits 2a to 2n.
Send 1 (in the case of FIG. 2) or S2 (in the case of FIG. 3). 5
Is an external charger, which can start and stop charging in response to a signal from the control circuit 4. The battery pack 1
It will be connected to the load (for example, a motor that drives an electric vehicle) from both ends of the
Illustration is omitted because it is not related to the charging control of the present invention. In FIG. 2, reference numerals 51 and 52 are reference voltage generators, 53 and 54 are comparators, 55 is an electronically controlled variable resistor, Q1 and Q2 are transistors, and R1 to R10 are resistors.

The operation of the circuits shown in FIGS. 1 and 2 will be described below. In FIG. 2, the voltage at the connection point between the reference voltage generator 51 and the resistor R3 becomes the reference voltage V2 (FIG. 4) that turns on the bypass circuit. The comparator 53 compares the voltage (voltage divided by the resistors R4 and R5) corresponding to the terminal voltage of the cell 1a with the reference voltage V2, and outputs a signal of "0" when the terminal voltage becomes higher. This turns on the transistor Q2, and a predetermined reference voltage is generated at the connection point between the reference voltage generator 52 and the resistor R8. A voltage Va obtained by dividing the reference voltage by the variable resistor 55 and the resistor R9.
And the emitter terminal voltage of the transistor Q1 are compared by the comparator 54, and the transistor Q1
Control. Therefore, the current flowing through the transistor Q1 has a value corresponding to the above voltage Va. Since this voltage Va has a value corresponding to the resistance value of the variable resistor 55, the larger the resistance value of the variable resistor 55, the smaller the current value flowing through the bypass circuit. The value of the variable resistor 55 becomes a value according to the control signal S1 given from the control circuit 4 of FIG. Further, the transistor Q1 is a switching element for turning on / off the bypass circuit, and the resistor R1,
A bypass current will flow through R2 and transistor Q1.

On the other hand, the control circuit 4 controls all the cells 1a based on the signals of the respective voltage detection circuits 2a to 2n before the start of charging.
A control signal for reading a voltage value of 1n, setting the above voltage Va according to the difference between the highest voltage value and the voltage value of each cell, and setting the value of the variable resistor 55 accordingly. S1 is sent to each bypass circuit. The voltage Va is set to a low value (the value of the variable resistor 55 is large) so that the bypass current value of the bypass circuit becomes small as the difference between the highest voltage and the voltage of each cell becomes large.

FIG. 4 is a characteristic diagram of the cell terminal voltage at the time of charging in the above-mentioned embodiment, showing two cells whose terminal voltages before charging are V0 and V1 (where V0 <V1) as an example. There is. In FIG. 4, charging is started at time t0. In this case, the bypass circuits of both cells are off, the charging currents are the same, and the terminal voltages of both cells rise with almost the same gradient. Next, at time t1, the terminal voltage of the cell having the higher initial voltage reaches the reference voltage V2,
By the operation as described above, the transistor Q1 of the bypass circuit is turned on, and the bypass current flows. Next, at time t2, the terminal voltage of the cell having the lower initial voltage reaches the reference voltage V2, and the bypass current also flows. However, since the bypass current flowing through both is set to a smaller value when the initial voltage value is lower, the charging current flowing through the cell (= charging current of the charger-bypass current) is
The lower the initial voltage value is, the larger the value is, and the higher the voltage value, the faster the charging. Therefore, as shown in FIG. 4, after the operation of the bypass circuit, the degree of increase in the terminal voltage of the cell has different characteristics, and at time t3, both reach the charge end voltage V3 (full charge). The control circuit 4 monitors the terminal voltage of the cell via each voltage detection circuit, and when the end-of-charge voltage V3 is reached, sends a signal to the external charger 5 to stop charging.

As described above, after the operation of the bypass circuit, the degree of increase in the terminal voltage of the cell has different characteristics. This characteristic depends on the value of the voltage Va, that is, the value of the variable resistor 55. Since it changes, the value of the variable resistor 55 may be set so that both reach the end-of-charge voltage V3 at the time t3 at the same time. Note that the above description exemplifies the case of two cells, but the same applies to the case of a large number of cells.

The above setting is specifically performed as follows. The difference δ between the highest voltage and the voltage of the cell is represented by the following (Formula 1). δ = (r · Ib + δv) Ib / (J−Ib) (Equation 1) where δ: difference between the highest voltage and the voltage of the cell r: internal resistance of the battery Ib: bypass current value δv: bypass circuit Difference between turn-on voltage and end-of-charge voltage J: Charger current In the above formula (1), for example, r = constant, δv = constant, J = constant simplifies The bypass current Ib is obtained from the difference δ from the voltage. According to the obtained value of the bypass current Ib, for example, the value of the corresponding variable resistor 55 is obtained from the memory map stored in advance, and the control signal S1 corresponding to the value is sent to each bypass circuit. Good.

As described above, in the embodiment shown in FIG. 2, the value of the bypass current is set according to the terminal voltage of each cell before the start of charging, and the bypass current is set smaller for the cell having the lower initial voltage. Since the charging current is increased, the useless current flowing in the bypass circuit is reduced, and the variation of each cell can be effectively reduced in a shorter time than before. Therefore, it is possible to reduce unnecessary power consumption and heat generation due to the current flowing through the bypass circuit.

Next, FIG. 3 is a diagram showing another embodiment of the bypass circuit 2. The circuit shown in FIG. 3 is similar to the resistor R4 shown in FIG.
Instead of the electronically controlled variable resistor 56, the variable resistor 55 is a normal resistor R11. The variable resistor 5
The resistance value of 6 changes according to the control signal S2 given from the control circuit 4. In the circuit of FIG. 3, the voltage compared with the reference voltage V2 by the comparator 53 is a value obtained by dividing the cell terminal voltage by the variable resistor 56 and the resistor R5. Therefore, when the resistance value of the variable resistor 56 changes, the voltage at which the bypass circuit turns on changes, and the larger the value of the variable resistor 56, the higher the terminal voltage, and the bypass circuit turns on. In this case, the control circuit 4 of FIG.
Before the start of charging, the voltage values of all the cells 1a to 1n are read based on the signals of the voltage detection circuits 2a to 2n, and variable according to the difference between the highest voltage value and the voltage value of each cell. The value of the resistor 56 is set, and the control signal S2 corresponding to the value is set.
To each bypass circuit. The resistance value of the variable resistor 56 is set to a large value so that the voltage value for turning on the bypass circuit becomes higher as the difference between the highest voltage and the voltage of each cell increases.

FIG. 5 is a characteristic diagram of the cell terminal voltage during charging in FIG. In FIG. 5, charging is started at time t0. In this case, the bypass circuits of both cells are off, the charging currents are the same, and the terminal voltages of both cells rise with almost the same gradient. Next, at time t4, the terminal voltage of the cell having the higher initial voltage reaches the reference voltage V4 set by the variable resistor 56 for the bypass circuit,
By the operation as described above, the transistor Q1 of the bypass circuit is turned on, and the bypass current flows. Next, at time t5, the terminal voltage of the cell having the lower initial voltage similarly reaches the reference voltage V5 (V4 <V5) of the circuit, and the bypass current also flows. In this case, although the bypass currents flowing through both have the same value, the cell having the lower initial voltage value is set to a large value V5 for turning on the bypass circuit, so that the cell terminal voltage is V
Until 5 is reached, the bypass circuit does not operate and charging is performed with a large charging current. Therefore, the amount of electricity charged in the cell having the lower initial voltage value increases, and the time t6
Then, both reach the charge end voltage V3 (full charge).

The control circuit 4 monitors the terminal voltage of the cell via each voltage detection circuit and sends a signal to the external charger 5 when the end-of-charge voltage V6 is reached to stop charging. As described above, the voltage for operating each bypass circuit is different, but the voltage value at which each bypass circuit operates, that is, the value of the variable resistor 55 of each circuit is such that both reach the end-of-charge voltage V6 at the time t6 at the same time. Just set it. In addition,
The above description exemplifies the case of two cells, but the same applies to the case of a large number of cells.

The above setting is specifically performed as follows. In the above (Formula 1), for example, Ib = constant,
For simplification with r = constant and J = constant, the difference δv between the voltage at which the bypass circuit is turned on and the end-of-charge voltage V6 is obtained from the difference δ between the highest voltage and the voltage of the cell. Since the end-of-charge voltage V6 is a constant value, by subtracting the end-of-charge voltage V6 from the obtained δv of each bypass circuit,
The voltage that turns on each bypass circuit can be obtained. According to the obtained voltage value, for example, the value of the corresponding variable resistor 56 may be obtained from a memory map stored in advance, and the control signal S2 corresponding thereto may be sent to each bypass circuit.

As described above, in the embodiment shown in FIG. 3, the value of the terminal voltage for operating the bypass circuit is set according to the terminal voltage of each cell before the start of charging, and the lower the initial voltage, the higher the voltage. Since the bypass circuit is set to be turned on by the voltage, useless current flowing in the bypass circuit is reduced, and the variation of each cell can be effectively eliminated in a shorter time than before. Therefore, it is possible to reduce unnecessary power consumption and heat generation due to the current flowing through the bypass circuit.

Next, FIGS. 6 and 7 are diagrams showing a second embodiment of the present invention. FIG. 6 is a circuit diagram showing the entire configuration, and FIG. 7 is a diagram showing voltage determination bypass circuits 21a to 21n. It is an example circuit diagram. In FIG. 6, 21a to 21n are voltage determination bypass circuits (details will be described later), and each of the cells 1a to 21n.
The voltage of 1n is judged and the judgment signals S3 to S are sent to the control circuit 22.
6 and sends control signals S7 to S from the control circuit 22.
In accordance with 9, the switching element (transistor Q3) is turned on to bypass the charging current. Reference numeral 22 is a control circuit composed of, for example, a computer. In addition, FIG.
The same reference numerals as in FIG. In addition, although it is connected to a load (for example, a motor that drives an electric vehicle) from both ends of the assembled battery 1 through the controller, it is not shown because it is not related to the charging control of the present invention. There is.

In FIG. 7, reference numerals 60 and 61 are reference voltage generators, 62, 63, 64 and 65 are comparators, and 6 is a comparator.
6, 67, 68 and 69 are photocouplers, and 70 and 71 are S
R flip-flops, 72, 73, and 74 are AND circuits,
75 and 76 are inverters (inversion circuits), Q3, Q4 and Q
5 is a transistor, S3, S4, S5 and S6 are determination signals sent from the voltage determination bypass circuit to the control circuit 22, S7,
S8 and S9 are control signals sent from the control circuit 22.

The operation will be described below. First, the basic operation of each part of the circuit of FIG. 7 will be described. Comparator 6
2 and the photocoupler 66, the comparator 63 and the photocoupler 67, and the comparator 64 and the photocoupler 68 respectively configure a voltage determination circuit, and the reference voltage generator 60.
Each reference voltage based on the voltage set in step 1 is compared with the terminal voltage of the cell 1a, and when the terminal voltage becomes higher, the determination signals S3 to S5 are sent to the control circuit 22, respectively. The reference voltage of the comparator 62 is set to the variation lower limit voltage, the reference voltage of the comparator 63 is set to the variation upper limit voltage (lower limit voltage <upper limit voltage), and the reference voltage of the comparator 64 is set to the charge end voltage. The signal is sent via the photocoupler because the voltage determination bypass circuits have different potentials and thus form a signal system independent of the assembled battery 1.

In the control circuit 22, among the above determination signals, S3 inputs all the outputs of the voltage determination bypass circuits by AND connection, and S4 inputs all the OR connections by input, and S4 inputs
All 5 are ORed and input. Therefore, the determination signal S3 is taken into the control circuit 22 when all the signals of all the circuits are "1", but the determination signals S4 and S5 are the control circuits when one of the signals is "1". 22 will be taken in. Therefore, when the determination signal S3 is input earlier than the determination signal S4, the terminal voltages of all cells are higher than the lower limit voltage, but there is no voltage equal to or higher than the upper limit voltage. Means that. On the other hand, when the determination signal S4 is input earlier, there are cells that have not reached the lower limit voltage but cells that are equal to or higher than the upper limit voltage. means.

When the terminal voltage of the cell reaches the end-of-charge voltage, the output of the comparator 64 becomes "0" and the output of the AND circuit 74 also becomes "0". Therefore, the transistor Q4 is turned on. At this time, if the transistor Q5 is on (details will be described later), a current flows through the reference voltage generator 61, the output of the comparator 65 becomes "1", and the transistor Q3 of the bypass circuit is turned on to bypass the charging current. . At this time, the determination signal S6 is sent from the photo coupler 69.
Are sent to the control circuit 22. ON / OFF of the transistor Q5 is controlled by setting or resetting the SR flip-flops 72 and 73 by the control signals S7 to S9 from the control circuit 22 and changing the output of the AND circuit 73. That is, when it is determined by the above determination that the variation is small, the output of the AND circuit 73 is set to "1", the output of the inverter 75 is set to "0", the transistor Q5 is turned off, and the bypass circuit is disabled (other conditions). Always off regardless of the setting. On the other hand, when it is determined that the variation is large, the output of the AND circuit 73 is "0" and the output of the inverter 75 is "1".
Turns on the transistor Q5 to enable the bypass circuit. In this state, the comparator 64
The bypass circuit is turned on when the output of is "0".

As described above, when the variation is small and the transistor Q5 is off, the terminal voltage reaches the charge end voltage, the output of the comparator 64 becomes "0", and the determination signal S5 is sent to the control circuit 22. Then, the control circuit 22
Sends a signal to the charger 5 to end the charging (see FIG. 8 below).
(See steps S7 and S8).

FIG. 8 is a flowchart of the control in FIGS. 6 and 7. Hereinafter, the control process will be described with reference to FIG. First, in step S1, it is determined whether or not the external charger 5 is connected. This is judged by the signal from the external charger 5 to the control circuit 22. When the external charger 5 is connected, the SR flip-flops 70 and 71 are reset in step S2 (reset signal S9).
Next, in step S3, it is determined whether or not the charging is started. If the charging is started, the voltage of each cell is detected in step S4, and in step S5, whether the voltage variation is within a certain range or not. Determine whether or not. “YES” in step S5
That is, if the variation is within a certain range, the voltage of each cell is detected in step S6, and it is determined in step S7 whether or not the voltage reaches the end-of-charge voltage. If there is even one cell that has reached the end-of-charge voltage, a signal is sent to the external charger 5 in step S8 to end the charging.

On the other hand, if "NO" in step S5, that is, if the variation is outside the fixed range, the voltage of each cell is detected in step S9, and in step S10, it is determined whether or not the voltage reaches the end-of-charge voltage. To judge. Then, with respect to the cell that has reached the charge cutoff voltage, in step S11, the bypass circuit connected to the cell is turned on to bypass the charge current. Next, in step S12, it is determined whether or not the bypass circuits of all cells are turned on, and "YE
When it becomes "S", in step S13, a signal is sent to the external charger 5 to end the charging. When the bypass current flowing through the bypass circuit is variable, all the bypass currents are external chargers. The charging may be terminated when the charging current becomes equal to the charging current, i.e., when the charging current flowing through all the cells becomes zero.

As described above, in this embodiment, when there is little variation in the terminal voltage of each cell, the bypass circuit is not activated and charging is performed if any one of the cells reaches the end-of-charge voltage. To finish. On the other hand, when the variation in the terminal voltage of each cell is large, the bypass circuit is activated for the cells that have reached the charge cutoff voltage, and the cells that have not reached the charge cutoff voltage are continuously charged. Then, when all the cells reach the charge cutoff voltage, the charge is terminated. Therefore, when the variation of each cell is small and the necessity of operating the bypass circuit is low, the operation of the bypass circuit is prohibited, so that wasteful power consumption due to the current flowing through the bypass circuit is suppressed and heat generation is prevented. It is possible to improve the durability of the bypass circuit constituent element. Further, when the variation of each cell is large, the bypass circuit is operated, so that the variation can be effectively eliminated.

In the embodiments shown in FIGS. 2, 3 and 7, the case where the charging current bypass circuit is a constant current bypass type circuit is illustrated, but it is constituted by a constant voltage type bypass circuit. You can also do it. Further, the circuit capacity can be reduced by using a PWM control type bypass circuit.

Further, the same configuration as that shown in FIG. 6 may be used as the voltage variation detection circuit in the circuit shown in FIG. In this case, the time difference when the reference voltage is reached may be used as the variation amount. Actually, a data map of the time difference (voltage variation amount) according to each current value is provided. As is clear from the configuration of FIG. 6, the advantage of this system is that a special voltage detection circuit (for example, 3 of FIG. 1) is not used, so that the number of components can be reduced.

[0037]

As described above, according to the first aspect of the invention, the useless current flowing in the bypass circuit is reduced, and the variation of each cell can be effectively eliminated in a shorter time than before. . Therefore, it is possible to reduce unnecessary power consumption and heat generation due to the current flowing through the bypass circuit. Further, in the invention according to claim 4, when there is little variation in each cell and the necessity of operating the bypass circuit is low,
Since the operation of the bypass circuit is prohibited, useless power consumption due to the current flowing through the bypass circuit can be suppressed, heat generation can be prevented, and the durability of the bypass circuit constituent element can be improved. Further, when the variation of each cell is large, the bypass circuit is operated, so that the variation can be effectively eliminated.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an overall configuration of a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a first embodiment of a bypass circuit 2 in FIG.

FIG. 3 is a circuit diagram showing a second embodiment of a bypass circuit 2 in FIG.

FIG. 4 is a voltage characteristic diagram of the circuit of FIG.

5 is a voltage characteristic diagram of the circuit of FIG.

FIG. 6 is a circuit diagram showing an overall configuration of a second embodiment of the present invention.

7 is a circuit diagram showing an embodiment of the voltage determination bypass circuit 21 in FIG.

FIG. 8 is a flowchart showing control in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Assembly battery 1a-1n ... Cell 2a-2n ... Bypass circuit 3a-3
n ... Voltage detection circuit 4 ... Control circuit 5 ... External charger 21a-21n ... Voltage determination bypass circuit 2
2 ... Control circuit 51, 52 ... Reference voltage generator 53, 5
4 ... Comparator 55 ... Electronically controlled variable resistor 60, 61 ... Reference voltage generator 62, 63, 64, 65 ... Comparator 66, 67, 68, 69 ... Photocoupler 70, 71 ... SR flip-flop 72, 73, 7
4 ... AND circuit 75 ... Inverters R1 to R10 ... Resistors Q1, Q2, Q3, Q4, Q5 ... Transistors S3, S4, S5, S6 ... Judgment signals S7, S8, S
9 ... Control signal

Claims (4)

[Claims] 1. An assembled battery in which a plurality of cells of a secondary battery are connected in series or series-parallel, and each of the cells or blocks of a plurality of cells are connected in parallel, and the cells or the cells are connected during charging. Bypass means for turning on the charging current when the voltage of the block is equal to or higher than a predetermined voltage, and the voltage of each cell before charging, or the voltage of the block composed of a plurality of cells is detected, and all cells or blocks are detected. Of the above voltages, a control for detecting the highest voltage, setting operating conditions for each bypass means based on the difference between the highest voltage and the voltage of each cell or block, and controlling each bypass means accordingly. A charging control device for an assembled battery, comprising: 2. The control means sets the bypass current value of the bypass circuit to a smaller value as the difference between the highest voltage and the voltage of each cell or block is larger, and the bypass current is supplied to each bypass means accordingly. The charge control device for an assembled battery according to claim 1, wherein the charge control device controls a current value. 3. The control means sets the value of the predetermined voltage for turning on the bypass circuit to a larger value as the difference between the highest voltage and the voltage of each cell or block is larger, and accordingly the value is set to a larger value. The charge control device for an assembled battery according to claim 1, wherein the bypass control means controls ON / OFF of each bypass means. 4. An assembled battery in which a plurality of cells of a secondary battery are connected in series or series-parallel, and each of the cells or blocks of a plurality of cells are connected in parallel, and the cells or the cells are connected during charging. When the voltage of the block is equal to or higher than a predetermined voltage, the bypass means is turned on to bypass the charging current, and the voltage of each cell or the voltage of the block composed of a plurality of cells is detected, and the voltage of all cells or the block is detected. When the variation is within a predetermined range, the operation of the bypass means is stopped, and when the variation is out of the predetermined range, a control means for controlling the bypass means to perform a normal operation is provided. Charge control device for assembled battery.