JP2000287370A - Voltage regulator and voltage regulation of battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent over-discharging and overcharging of respective unit cells and avoid restriction as much as possible due to variations in the capacities of respective unit cells on the charging capacity of a battery formed by connecting respective unit cells in series. SOLUTION: The terminal voltage of a battery 38 formed by connecting four unit cells 21 (1) to 21 (4) in series is divided by a voltage dividing circuit 40' formed by connecting resistors 23a, 24a, 25a, 39 in series. A logic circuit part 67 turns on the switch 35 of a discharge circuit 33 for a unit cell 21 whose internal terminal voltage is higher than mean voltage based on the output signal of comparators 27 to 41L for permitting its automatic discharge and ultimately attains roughly equal terminal voltages for all the unit cells 21 to resolve variations. When the ambient temperature is detected by a thermistor 61 and is at the prescribed temperature or less, the logic circuit 67 prohibits the cells 21 from discharging upon receiving the output signal of the comparator 62.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembled battery comprising a plurality of unit cells connected in series, and a voltage adjusting device for the assembled battery for adjusting the variation in terminal voltage between the unit cells. Regarding the adjustment method.

[0002]

2. Description of the Related Art In recent years, a hybrid electric vehicle (hereinafter, referred to as a hybrid vehicle) combining a mechanism of an electric vehicle and a gasoline engine has been developed for the purpose of achieving both low pollution and high running performance.
HEV) has been developed. Since an HEV is equipped with a gasoline engine, it can maintain the same running performance as a gasoline-powered vehicle without using a large-capacity battery as an electric vehicle, but has low engine efficiency and emits carbon dioxide and nitrogen oxides. When the motor rotates at a low rotation speed, the motor is driven by the battery, so that low pollution can be achieved.

[0003] Even in such an HEV, electric power supplied from a battery is used at the time of starting or at the time of full acceleration.
High output is required for batteries. Also, HEV is
Since many components such as an engine, a motor / generator, and a battery must be mounted, and the weight of the entire vehicle increases, the battery must be as high in performance and light as an electric vehicle. Have been.

[0004] Under such circumstances, lithium batteries have attracted attention as an alternative to lead, nickel cadmium, nickel hydride batteries and the like. Lithium batteries have a weight energy density that is about three to four times higher than lead or nickel cadmium batteries of the same capacity, and are expected to be applied as suitable for HEVs that require small size and light weight. I have.

However, lithium batteries are susceptible to overcharging and overdischarging, and if not used within a specified voltage range, the materials may decompose and the capacity may be significantly reduced, or the battery may become unusable due to abnormal heat generation. There is. Therefore, when using a lithium battery, the upper limit voltage and the lower limit voltage are clearly specified, and charge / discharge control is performed so that the terminal voltage is within the range, or a protection circuit that limits the voltage range is used as a set. It is common to use.

[0006] Incidentally, batteries used in electric vehicles and HEVs require a high voltage to drive a motor, and therefore are usually constituted by connecting a plurality of unit cells in series. For example, to obtain a battery voltage of 300 V, about 150 cells are connected in series for a 2 V lead battery per unit cell, and about 80 cells are connected in series for a 3.6 V lithium battery per unit cell. Become.

In the case of charging a battery pack formed by connecting a number of unit cells in series as described above, charging has conventionally been controlled by monitoring the voltage between the positive and negative terminals of the battery pack. For example, the voltage range per unit cell is 1.8-2.
In the case of 150 lead batteries connected in series at 4 V, charge / discharge control was performed so that the voltage range of the assembled battery would be in the range of 270 to 360 V.

In this case, a problem is a variation in terminal voltage between the unit cells based on a state of charge (hereinafter, referred to as SOC) of each unit cell. In the state of being connected in series, the current flowing through each unit cell is equal, but the remaining capacity of each unit cell always varies, so that the terminal voltage of each unit cell also differs. This variation in the remaining capacity is mainly caused by a difference in self-discharge and charge / discharge efficiency for each cell, and is accumulated and expanded with time.

That is, even if the charging is controlled by monitoring the total voltage between the terminals of the assembled battery, the terminal voltage of each unit cell as a component of the assembled battery is (voltage between terminals of the assembled battery) /
Some are higher or lower than the average voltage obtained by (number of unit cells). Therefore, there is a unit cell that is overcharged when charged to the upper limit voltage and overdischarged when discharged to the lower limit voltage.

[0010] However, NiCd or nickel-metal hydride batteries have little deterioration in performance even if they are overdischarged or overcharged, and lead batteries have no particular problem in safety even if their performance is deteriorated. Since it will not be impossible, it is sufficient to control with reference to only the voltage between both ends of the assembled battery, but when using a lithium battery as a multi-series assembled battery, each unit cell will be in an overcharged or overdischarged state. It is indispensable to take measures to prevent this from happening.

[0011]

In consideration of such measures, for example, in Japanese Utility Model Laid-Open Publication No. 2-136445, during charging, the highest value of the terminal voltage of each unit cell is detected and the highest value is detected. Control based on voltage,
At the time of discharging, a technology is disclosed in which the lowest value is detected and control is performed based on the lowest voltage. In this conventional technique, it is possible to control the charging and discharging of all the unit cells within a predetermined voltage range. However, when the SOC of each unit cell is shifted, the charging and discharging are performed by the unit cells having the highest and lowest SOC.
There is a problem that the discharge is limited and the capacity is reduced by the amount of the shift of the SOC.

To solve such a problem, for example, Japanese Unexamined Patent Publication No. 6-253463 discloses a discharge circuit (bypass circuit) including a resistor and a switch in each unit cell.
Are connected in parallel, and when the voltage of the unit cell fluctuates, the switch of the discharge circuit corresponding to the unit cell having a higher voltage is closed to discharge, or a so-called balance that shunts the charging current at the time of charging. There is disclosed a technique of reducing a voltage difference between unit cells by charging and discharging.

JP-A-8-213055 discloses that the charge state of each unit cell is monitored, and for a unit cell that has reached a fully charged state, a charge current is diverted to a bypass circuit so that all unit cells are charged. A technique for aligning cells in a fully charged state and eliminating variations has been disclosed.

FIG. 16 shows a specific configuration example of these prior arts. The assembled battery 1 includes a plurality (n) of unit cells 2 (1),
, 2 (n) are connected in series, and a discharge resistor 3 is connected to both ends of each unit cell 2.
a and a switch 3b composed of a transistor, FET, etc.
Are connected in series, and a discharge circuit 3 and a voltage detector 4 configured respectively are connected. The output signal of the voltage detector 4 is provided to the MPU 7 via the multiplexer 5 and the A / D converter 6.

The MPU 7 refers to the terminal voltage of each unit cell 2 at regular time intervals and stores the same in the memory 8, and discharges or charges the unit cell 2 having a higher terminal voltage in each unit cell 2. A control signal is output to the decoder 9 to bypass the current. When the control signal is decoded by the decoder 9, the control signal is output to the switch 3b of the discharge circuit 3 of the corresponding unit cell 2 via the photocoupler (or isolation amplifier) 10. Then, the switch 3b of the discharge circuit 3 is closed, and the discharge of the unit cell 2 or the bypass of the charging current is performed via the resistor 3a.

In such a configuration, the discharge circuit 3, the voltage detector 4, the photocoupler 10, and the like are required by the number of the unit cells 2, and there is a problem that the total number of parts increases. In addition, the number of unit cells 2 that can be controlled by one MPU 7 is limited to about 10 to 20 due to limitations on insulation (breakdown voltage) and controllability.

Therefore, in order to apply to an HEV or an electric vehicle, as shown in FIG.
The module 11 is divided into groups of about 0 unit cells 2 and the control of each group is assigned to the corresponding MPU 7 in the configuration of FIG. 16, and the upper MPU 7 </ b> H controls the MPUs 7 of the modules 11.
Need to be arranged. For example, when 80 lithium batteries are used for the unit cell 2, 1
The configuration is 0 × 8 groups or 20 × 4 groups. As a result, 5 or 9 MPUs, which are expensive parts, are required, and it is inevitable that the cost will increase.

Therefore, Japanese Patent Application Laid-Open No. Hei 8-55643 discloses a technique which enables charge control without using an MPU. As shown in FIG. 18, a series circuit of two resistors 14a and 14b having the same resistance value is connected in parallel to a battery pack 13 composed of two unit cells 12 connected in series, and the comparator 15 The potential of the common connection point VCM of the two unit cells 12 and the potential of the common connection point VRM of the two resistors 14a and 14b are compared.

The output terminal of the comparator 15 is connected to the base of an npn-type transistor 17a via a base resistor 16a and to the base of a pnp-type transistor 17b via a base resistor 16b. The collectors of the transistors 17a and 17b are connected to the positive electrode and the negative electrode of the battery pack 13 via discharge resistors 18a and 18b, respectively, and the emitters of both are commonly connected to a common connection point VCM. The above constitutes the adjustment module 19.

Then, the unit cells 12 (1) and 12 (2)
If the terminal voltages are VC1 and VC2, respectively, when VC1> VC2 and potential VCM <potential VRM, the output terminal of the comparator 15 becomes high level and the transistor 17a is turned on, so that the unit cell 12 (1) has the resistance 18a. Discharged through. When VC1 <VC2 and the potential VCM> V potential RM, the output terminal of the comparator 15 becomes low level, and the transistor 17b is turned on.
(2) is designed to be discharged via the resistor 18b.

However, each of these adjustment modules 19 is configured to adjust the variation of the terminal voltage for each of the two unit cells connected thereto. Therefore, assuming that this adjustment module 19 is applied to several tens or more, for example, N (N is a natural number) series assembled batteries, (N-1) adjustment modules 19 must be used correspondingly. Then, adjustment errors between the adjustment modules 19 may be accumulated, and there is no guarantee that high-precision control can be achieved as a whole.

The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent overdischarge and overcharge of each unit cell and to form a unit configured by connecting these unit cells in series. It is an object of the present invention to provide a voltage regulator for a battery pack, which can minimize the charge capacity of a battery due to variations in the capacity of each unit cell.

[0023]

According to the voltage adjusting device for an assembled battery according to the first aspect or the voltage adjusting method for the assembled battery according to the fifth aspect, the voltage dividing means sets the terminal voltage of the assembled battery to the unit cell. The voltage is divided according to the number, and the potential comparing means compares the potential of a specific connection point among the plurality of connection points between the unit cells with the potential of the voltage division point corresponding to the connection point. When the discharge control unit determines that the terminal voltage of the unit cell corresponding to the specific connection point is higher than the average voltage based on the comparison result by the potential comparison unit, the discharge control unit controls to discharge the unit cell. .

Therefore, it is possible to adjust the terminal voltage of the unit cell corresponding to a specific connection point to be equal to the average voltage, thereby adjusting the variation of the terminal voltage, that is, the variation of the remaining capacity. The use efficiency of the battery pack can be improved while preventing charging.

The discharge control means prohibits the discharge of the unit cell when it judges that the ambient temperature has become equal to or lower than a preset reference temperature. That is, in a low-temperature environment, the internal resistance of a unit cell may become extremely large, and if the voltage of a unit cell falls below the minimum voltage at that time due to a voltage drop caused by discharging, it is necessary to adjust the internal resistance. There is a risk of adjusting the voltage of a unit cell that does not have any. Therefore, when the ambient temperature becomes equal to or lower than the reference temperature, the occurrence of such a situation can be avoided by prohibiting the discharge.

According to the voltage adjusting device for a battery pack according to the second aspect or the voltage adjusting method for the battery pack according to the sixth aspect, the discharge control means is configured to control the discharge result by the potential comparing means. When it is determined that the terminal voltage of the unit cell corresponding to the specific connection point is higher than the average voltage, the unit cell is controlled so as to be discharged. The use efficiency of the battery pack can be improved while preventing discharge and overcharge.

The discharge control means prohibits the discharge of the unit cell when it determines that the voltage between the terminals of at least one of the plurality of unit cells has become equal to or lower than a preset reference voltage. That is, when a short circuit or the like occurs in any one of the plurality of unit cells and the voltage of the cell decreases, the adjustment may be performed so that the voltages of the other unit cells are correspondingly reduced. Therefore, when the inter-terminal voltage of at least one unit cell becomes equal to or lower than the reference voltage, by prohibiting the discharge, it is possible to prevent the voltages of the other unit cells from being carelessly reduced.

According to the third aspect of the present invention, similarly to the first, second, fifth, or sixth aspect, the discharge control means includes a potential comparison unit. When it is determined that the terminal voltage of the unit cell corresponding to the specific connection point is higher than the average voltage based on the comparison result by the means, the unit cell is controlled so as to be discharged. Thus, the use efficiency of the battery pack can be improved while preventing overdischarge and overcharge.

The discharge control means prohibits the discharge of the unit cell when determining that the voltage between the terminals of at least one of the plurality of unit cells has become equal to or higher than a preset reference voltage. That is, by setting the upper limit of the voltage adjustment operation, it is possible to limit the range of the voltage or the remaining capacity at which the adjustment operation is performed. Therefore, the variation in the full charge capacity between the unit cells is different from the variation in the remaining capacity. In particular, in a range where the remaining capacity is large (close to full charge), even if the remaining capacity is the same, the terminals between the unit cells have different terminals. Unnecessary voltage adjustment operation is performed due to the voltage variation, and it is possible to suppress unnecessary discharge.

According to the voltage adjusting device for a battery pack according to the fourth aspect and the voltage adjusting method for the battery pack according to the eighth aspect, as in the first, second, third or fifth, sixth, and seventh aspects, the discharge control means is provided. Controls the unit cell to discharge when the terminal voltage of the unit cell corresponding to the specific connection point is higher than the average voltage based on the result of comparison by the potential comparing means. Can be adjusted, and the use efficiency of the assembled battery can be improved while preventing overdischarge and overcharge.

The path cutoff means disposed in the discharge path of each unit cell and near the unit cell cuts off the path when an overcurrent flows through the discharge path. That is, for example, if any one of the plurality of unit cells is disconnected for some reason while the battery pack is being charged or discharged, the assembled battery is placed at both ends of the disconnected part. High voltage may be generated due to inductance of a circuit connected to the battery. In such a case, since an overcurrent flows in the discharge path connected to both ends of the disconnection point, the discharge path is cut off by the path cutoff means to protect the voltage regulator from destruction. Can be.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment)
A first embodiment in which the present invention is applied to an assembled battery in which three unit cells are connected in series will be described with reference to FIGS. In FIG. 1 showing the electrical configuration, three unit cells 21 (1), 21 (2),
21 (3) is connected in series to form a battery pack 22. A voltage dividing circuit (voltage dividing means) 26 having resistors 23, 24, and 25 connected in series is connected to the battery pack 22 in parallel.

The resistors 23 and 24 are formed of a series circuit of resistors 23a and 23b, 24a and 24b, and the resistance ratio is set to, for example, about 4000: 1. The resistances of the resistors 23a, 24a and 25 are set to be equal to each other, and the resistances of the resistors 23b and 24b are so small that they can be ignored compared to these resistances. Accordingly, the terminal voltage of the battery pack 22 is substantially divided into three equal parts by the three resistors 23a, 24a and 25.

Here, the negative terminal of the assembled battery 22 is Jc0, and the positive terminal is Jc3, and the unit cell 21 (1) between them is provided.
And the connection point of 21 (2) is Jc1, and the connection point of the unit cells 21 (2) and 21 (3) is Jc2. Also, the voltage dividing circuit 2
The negative terminal of Jr0 is Jr0, the positive terminal is Jr3, and the common connection points of the resistors 23a and 23b, 24a and 24b between them are Jr1 and Jr2. The common connection point between the resistors 23b and 24a is Jr1 ', and the common connection point between the resistors 24b and 25 is Jr2'. Hereinafter, each of the connection points is referred to as a terminal.

The inverting input terminal of the comparator 27H and the non-inverting input terminal of the comparator 27L are commonly connected to the terminal Jc1. The non-inverting input terminal of the comparator 27H is connected to the terminal Jr1, and the comparator 27L
Is connected to the terminal Jr1 '. The two comparators 28H and 28L make the same connection to the unit cell 21 (2) and the resistor 24. Incidentally, the four comparators 27H, 27L, 28H and 28L constitute potential comparing means.

The output terminal of the comparator 27L is connected to one input terminal of an AND gate 30 via an INV (inverter) gate 29, and the output terminal of the comparator 27H is connected to one input terminal of the AND gate 31. It is connected to the. The output terminal of the comparator 28L is connected to the other input terminal of the AND gate 30, and the output terminal of the comparator 28H is connected to INV.
The gate 32 is connected to the other input terminal of the AND gate 31.

The discharge circuit 33 is formed by connecting a discharge resistor 34 and a normally open switch 35 in series. The three discharge circuits 33 (1) to 33 (3) are connected in series so as to correspond to the unit cells 21 (1) to 21 (3), and are connected in parallel to both ends of the battery pack 22. I have.
The common connection point of the discharge circuits 33 (1) and 33 (2) is connected to the terminal Jc1, and the common connection point of the discharge circuits 33 (2) and 33 (3) is connected to the terminal Jc2. I have.

Each of the switches 35 (1) to 35 (3) is composed of, for example, a transistor or an FET, and closes (conducts) when a high-level control signal is supplied to a control signal terminal. I have. The control signal terminals of the switches 35 (1) and 35 (3) are connected to the output terminals of the comparators 27L and 28H, respectively. The control signal terminal of the switch 35 (2) is OR
The two input terminals of the OR gate 36 are connected to the output terminals of the gates 36 and 31.
Are connected respectively to the output terminals.

The NOT gates 29 and 32, the AND gates 30 and 31, and the OR gate 36 constitute a logic circuit section 37. In addition, the discharge circuit 33 and the logic circuit unit 37 constitute a discharge control unit. By the way, although not specifically shown, the comparators 27H, 27L,
28H and 28L and the power for operation of the logic circuit unit 37 are generated and supplied from the assembled battery 22.

Next, the operation of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. Here, the unit cells 21 (1),
The terminal voltages of 21 (2) and 21 (3) are respectively V1, V2,
V3. Also, each terminal Jc1, with reference to the terminal Jc0,
The potentials of Jc2 and Jc3 are set to Ec1, Ec2, and Ec3, respectively.
The potential of each terminal Jr1, Jr2, Jr3 with respect to r0 is
r1, Er2, and Er3. Then, the potentials Ec1, Ec2, Ec3
Are represented as in equation (1). Ec1 = V1 Ec2 = V1 + V2 (1) Ec3 = V1 + V2 + V3 = Er3

The resistances of the resistors 23a, 24a, and 25 are equal, and if the resistors 23b and 24b are ignored, the unit cell 21 is disposed at both ends of each of the resistors 23a, 24a, and 25.
The average value of the terminal voltages of (1), 21 (2) and 21 (3) is applied, respectively. Therefore, the potentials Er1, Er2, Er3 are each represented by the following equation (2). Er1 = Ec3 / 3 = (V1 + V2 + V3) / 3 Er2 = 2 · Ec3 / 3 = 2 (V1 + V2 + V3) / 3 (2) Er3 = 3 · Ec3 / 3 = V1 + V2 + V3

Here, the four comparators 27H, 27
Considering the input conditions under which the output levels of L, 28H, and 28L go high "H", respectively, is as follows. Note that the terminal voltage of the resistors 23b and 24b is Vα. Comparator 27H: Er1> Ec1 Comparator 27L: Er1 + Vα <Ec1 → Er1 <Ec1−Vα Comparator 28H: Er2> Ec2 (3) Comparator 28L: Er2 + Vα <Ec2 → Er2 <Ec2−Vα

That is, the comparator 27H outputs the divided potential E
When r1 is higher than the potential Ec1 of the terminal Jc1, the comparator 27L goes high when the divided potential Er1 becomes lower than the potential Ec1 minus the minute voltage Vα. Therefore, the divided potential Er1 becomes Ec1
When it is considered that the potential is in the range of −Vα ≦ Er1 ≦ Ec1 and is substantially equal to the potential Ec1, the comparators 27H and 27L
Are at low level. The comparator 28
The same applies to H, 28L with respect to the divided potential Er2 and the potential Ec2 of the terminal Jc2.

The four comparators 27
H, 27L, 28H, and 28L, by logically synthesizing the output levels, the three switches 35 (1) to 35 (1) to 35
The conditions for setting (3) to the ON state "1" are as shown in the truth table shown in FIG. However, “x” indicates an arbitrary level.

V3>V2> V1 Here, the operation from the initial state where the terminal voltages of the unit cells 21 (1) to 21 (3) are V3>V2> V1 will be described with reference to FIG. I do.

[Period A] In this case, Er1 = (V1 + V2 + V3) / 3> V1 = Ec1> Ec1 Er2 = 2 (V1 + V2 + V3) / 3> V1 + V2 = Ec2> Ec2 (4) Therefore, the comparators 27H, 28H Are high level "H". Therefore, in the truth table shown in FIG. 2, the switch 35 (3) is in the ON state “1”.
Since the following condition is satisfied, the unit cell 21 (3) is discharged by the discharge circuit 33 (3).

When the terminal voltage V3 decreases due to the discharge of the unit cell 21 (3), the terminal voltage E of the battery pack 22 decreases.
c3 (= Er3) decreases, and accordingly, the divided potential Er2 also decreases. When V3 <V2 and Er2 = Ec2, the output signal of the comparator 28H becomes low level "L".
Becomes

At this time, as shown at time point P in FIG. 3, the terminal voltage V3 is the average cell voltage of the assembled battery 22, but since the unit cell 21 (2) is not discharged, V2>
The relationship of V1 is maintained, and Er1 in equation (4)>
Ec1, does not change. Therefore, the output signal of the comparator 27H remains “H”. Then, in the truth table shown in FIG. 2, the condition that the switch 35 (2) is turned on “1” is satisfied, so that the unit cell 21 (2) is discharged by the discharge circuit 33 (2) at the same time. Discharge circuit 33
The discharge of the unit cell 21 (3) due to (3) stops.

Here, regarding the comparators 27H and 27L, the output signal of the comparator 27H is "L",
The condition that the output signal level of the comparator 27L does not matter is at least that Er2 is not higher than Ec2, that is, Er2 is substantially equal to Ec2 or Er2.
Is lower than Ec2, which means that Er2 ≦ Ec2.

[Period B] When the terminal voltage V2 decreases due to the discharge of the unit cell 21 (2), the voltages Ec2 and Er3 decrease, and accordingly, the divided potential Er2 also decreases. Here, when comparing Er2 and Ec2, from the expressions (1) and (2), Ec2 = V1 + V2 Er2 = 2 (V1 + V2 + V3) / 3, and the effect of the decrease in the terminal voltage V2 is clearly Ec2. large. Therefore, the magnitude relationship between the two becomes Er2> Ec2 again from Er2 = Ec2, and the output signal of the comparator 28H becomes "H" again. Then, the condition that the switch 35 (3) is turned on “1” is satisfied, and the discharge circuit 33 is turned on.
The discharge by (2) is stopped, and the unit cell 21 (3) is discharged by the discharge circuit 33 (3).

That is, in this case, the unit cell 21 (2) is discharged and the terminal voltage V2 is reduced, so that the unit cell 21 (2) is discharged.
Will also decrease. Then, the terminal voltage V
3 also has a difference from the average voltage if its potential is maintained from the time point P, so that the unit cell 21
(3) is discharged again, and acts so that the terminal voltage V3 becomes substantially equal to the average voltage.

When the terminal voltage V3 decreases due to the discharge of the unit cell 21 (3) and becomes substantially equal to the average voltage again, the divided potentials Er3 and Er2 decrease as described above, and Er2 =
It becomes Ec2, and the output signal of the comparator 28H becomes "L". Also, since the unit cell 21 (2) is not discharged, V
Since 2> V1 and Er1> Ec1, the output signal of the comparator 27H remains “H”. Then, the condition that the switch 35 (2) is turned on "1" is satisfied, so that the unit cell 21 (2) is discharged and the discharge of the unit cell 21 (3) is stopped at the same time.

That is, in the period B, the switch 35
(2) and 35 (3) are alternately turned on, and the unit cells 21 (2) and 21 (3) are alternately discharged. Also, in FIG. 3, the terminal voltages V2 and V3 are shown to decrease linearly, but in practice, when one of the potentials decreases, the other does not change. That state is alternately repeated in a short period of time.

Finally, Er1 = Ec1, Er2 = E
c2, that is, when V1 = V2 = V3, the comparator 2
The output levels of 7H, 27L, 28H, 28L are all "L", and the discharge of unit cells 21 (1) to 21 (3) stops. Thus, the operation of adjusting the variations in the terminal voltages V1, V2, and V3 is completed.

V1>V2> V3 Next, the operation when V1>V2> V3 as the initial state will be described. In this case, Er1 = (V1 + V2 + V3) / 3 <V1 = Ec1 <Ec1 Er2 = 2 (V1 + V2 + V3) / 3 <V1 + V2 = Ec2 <Ec2 (5) Therefore, the output signals of the comparators 27L and 28L are both " H ”. Accordingly, in the truth table shown in FIG. 2, the condition that the switch 35 (1) is turned on “1” is satisfied, and the discharge circuit 33 (1) uses the unit cell 2
1 (1) is discharged.

When the terminal voltage V1 decreases due to the discharge of the unit cell 21 (1), the terminal voltage Ec1 decreases.
The voltages Er3 and Er1 decrease accordingly. Here, Er1
When Ec1 is compared with Ec1, from Eqs. (1) and (2), Ec1 = V1 Er1 = (V1 + V2 + V3) / 3, and the effect of the decrease in the terminal voltage V1 is clearly larger in Ec1. Therefore, Ec1 approaches Er1 and eventually Er1 =
Ec1, and the output signal of the comparator 27L becomes "L". Then, the condition that the switch 35 (2) is turned on “1” is satisfied, the discharge by the discharge circuit 33 (1) is stopped, and the unit cell 21 (2) is discharged by the discharge circuit 33 (2).
Is discharged.

When the terminal voltage V2 decreases due to the discharge of the unit cell 21 (2), the voltages Er3 and Er1 decrease. Further, since the unit cell 21 (1) is not discharged, V
1 = Ec1 does not decrease. As a result, Er1 <Ec1 again, and the output signal of the comparator 27L becomes "H" again. Then, the discharge by the discharge circuit 33 (2) stops,
The unit cell 21 (1) is discharged by the discharge circuit 33 (1).

When the terminal voltage V1 decreases due to the discharge of the unit cell 21 (1), the terminal voltage Ec1 decreases.
Again, Er1 = Ec1, the discharge by the discharge circuit 33 (1) is stopped, and the unit cell 21 is discharged by the discharge circuit 33 (2).
(2) is discharged. Thereafter, the switches 35 (1), 35
(2) are alternately turned on, and the unit cells 21 (1),
21 (2) are discharged alternately. And finally Er1
= Ec1, Er2 = Ec2, that is, when V1 = V2 = V3, the discharge of the unit cells 21 (1) to 21 (3) stops, and the action of adjusting the variation of the terminal voltages V1, V2, V3 ends. This voltage change is obtained by exchanging V1 and V3 in FIG.

V2> V3 = V1 Next, the operation when the initial state is V2> V3 = V1 will be described with reference to FIG. In this case, Er1 = (V1 + V2 + V3) / 3> V1 = Ec1> Ec1 Er2 = 2 (V1 + V2 + V3) / 3 <V1 + V2 = Ec2 <Ec2 (6) Therefore, the output signals of the comparators 27H and 28L are both " H ”. At this time, the comparator 27
The output signals of L and 28H are both "L", and in the truth table shown in FIG. 2, the switch 35 (2) is in the ON state "1".
Since the following condition is satisfied, the unit cell 21 (2) is discharged by the discharge circuit 33 (2).

When the terminal voltage V2 decreases due to the discharge of the unit cell 21 (2), the voltages Ec2 and Er3 decrease. Accordingly, the divided potentials Er2 and Er1 also decrease.
Er1 approaches Ec1. Also, as described above, Er
Between Ec2 and Ec2, the effect of the decrease in the terminal voltage V2 is clearly greater for Ec2, so Ec2 approaches Er2. Finally, Er1 = Ec1, Er2 = Ec2, V1 = V2
= V3, the variation adjustment operation of the terminal voltages V1, V2, V3 ends.

That is, in the transient state, only the terminal voltage V2 is always higher than the average voltage of the unit cell 21 and the terminal voltages V1 and V3 are always lower than the average voltage of the unit cell 21, so that only the unit cell 21 (2) is discharged all the time. Will be done.

As described above, according to the present embodiment, the terminal voltage of the battery pack 22 formed by connecting three unit cells 21 (1) to 21 (3) in series is determined by connecting the resistors 23, 24 and 25 in series. The voltage is divided by a voltage dividing circuit 26 connected to
7 automatically discharges the unit cells 21 (1) to 21 (3) whose internal terminal voltages are higher than the average voltage based on the output signals of the comparators 27H to 28L, and finally all the unit cells 21 (1) to 21 (3). The terminal voltages of the cells 21 (1) to 21 (3) are made substantially equal to eliminate the variation.

For example, with respect to the unit cell 21 (2), the logic circuit unit 37 determines that the potential Ec2 of the connection point Jc2 on the positive electrode side is higher than or substantially equal to the potential Er2 of the corresponding voltage dividing point Jr2 (Ec2 ≧ Er2) and the potential Er1 of the corresponding voltage-dividing point Jr1 is higher than the potential Ec1 of the connection point Jc1 on the negative electrode side (Ec1 <Er1), or the potential Ec2 is higher than the potential Er2 (Ec2> Er2) and the potential When the potential Er1 is higher than or equal to Ec1 (Ec1 ≦ Er1), the terminal voltage V
2 is higher than the average voltage.

Therefore, it is possible to reliably determine the level of the terminal voltage of the unit cell 21 and the average voltage obtained from the voltage dividing circuit 26, and to eliminate the variation in the terminal voltage between the unit cells, ie, the remaining capacity. Therefore, overcharging and overdischarging can be prevented, and the use efficiency of the battery pack 22 can be improved.

According to the present embodiment, a lithium battery having a high energy density but requiring more strict measures for overcharging and overdischarging is applied to the assembled battery 22 as the unit cell 21. It is possible to take full advantage of the performance of a lithium battery while safely controlling charging and discharging, and utilize it.

The conventional voltage regulator uses an MPU, and it is necessary to supply a stable level of operation power to the MPU. Therefore, conventionally, the operation power supply is supplied from a control power supply (12 V battery, corresponding to a so-called gasoline vehicle battery) provided separately from the drive power supply battery.

On the other hand, according to the present embodiment, the power supply for operating the comparators 27H to 41L and the logic circuit section 37 is obtained from the battery pack 22, which is the drive power supply. That is, unlike the related art, the logic circuit unit 37 can be configured by a combination of logic gates without using an MPU or the like, so that the power consumption is extremely small as compared with the related art. Since the battery pack 22 has a three-series configuration, its terminal voltage is about 3.6 × 3 = 10.8 (V), which is suitable for producing an operation power supply of about 3.3 to 5 V. . In addition, these circuits are different from MPU
Since operation is possible even if the power supply voltage drops slightly,
These operation power supplies can be obtained from the assembled battery 22. Therefore, it is possible to suppress the power consumption of the control power supply having a relatively small capacity with respect to the operation power supply.

(Second Embodiment) FIGS. 5 and 6 show a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Only the parts will be described. In the second embodiment, an assembled battery 3 in which the unit cells 21 (4) are added to the assembled battery 22 and the number of series-connected batteries is four.
8 is applied.

The resistance 25 of the voltage dividing circuit 26 is
3 and 24, a resistor 25a having a resistance ratio of 4000: 1.
And 25b, and a voltage dividing circuit 40 is formed by adding a resistor 39 corresponding to the unit cell 21 (4) in series. Then, the unit cells 21 (3) and 21
Comparators 41H and 41L (potential comparison means) are connected to the connection point Jc3 of (4) and both ends of the resistor 25b in the same manner as the comparators 28H and 28L.

On the other hand, the output terminal of the comparator 28L
The other input terminal of the AND gate 43 is connected to the output terminal of the comparator 41L via the NOT gate 42. The output terminal of the comparator 28H is replaced with the control terminal of the switch 35 (3), and
4 is connected to one input terminal, and the other input terminal of the AND gate 44 is connected to the output terminal of the comparator 41H via the NOT gate 45.

The output terminals of the AND gates 43 and 44 are respectively connected to the input terminals of the OR gate 46. The output terminal of the OR gate 46 is connected to the switch 35.
It is connected to the control terminal of (3). Also, unit cell 2
The control terminal of the switch 35 (4) constituting the discharging circuit 33 (4) provided corresponding to 1 (4) is connected to the output terminal of the comparator 41H.

It should be noted that the constituent elements of the logic circuit section 37 are NOT
The addition of the gates 42 and 45, the AND gates 43 and 44, and the OR gate 46 constitute the logic circuit unit 47. The discharge circuit 33 plus the logic circuit 47 constitutes a discharge control means. In addition, the first
As in the embodiment, the power supply for operating the comparators 27H to 41L and the logic circuit unit 47 is generated and supplied from the battery pack 38.

Next, the operation of the second embodiment will be described with reference to FIG. In the truth table of the logic circuit unit 47 shown in FIG. 6, the second to fourth stages from the bottom are determined by the logic of the comparators 27H to 28L as in FIG. 2 of the first embodiment. In addition, only the condition that both the comparators 41H and 41L are at the low level is applied to the lowermost stage in which both the switches 35 are turned off.

The switches 35 at the fifth and sixth stages from the bottom
The condition that (3) is turned on "1" is determined by the switch 35
Comparators 27H to 28L in which (2) is turned on
Is similarly applied to the comparators 28H to 41L. The condition that the uppermost switch 35 (4) is turned on is determined by the comparator 41.
The condition is that H is at the high level.

That is, the ON condition of the switch 35 (1) corresponding to the most negative unit cell 21 (1) of the battery pack 38 is such that the potential of the positive connection point Jc1 is equal to the voltage dividing point Jr1 (Jr
The switch 35 is determined only by the output logic of the comparator 27L that outputs a high-level signal when the potential is higher than the potential of 1 '), and corresponds to the most positive unit cell 21 (4).
The ON condition of (4) is determined only by the output logic of the comparator 41H that outputs a high-level signal when the potential of the voltage dividing point Jr3 is higher than the potential of the negative connection point Jc3.

The ON condition of the switch 35 (2) corresponding to, for example, the unit cell 21 (2) disposed therebetween is determined by the comparators 28H and 28L disposed on the positive side of the unit cell 21 (2). , And comparators 27H and 27L arranged on the negative side.

According to the second embodiment configured as described above, even when the present invention is applied to a battery pack 38 having a four-series
The same effect as that of the embodiment can be obtained. Further, unlike the conventional case, even when the present invention is applied to a multi-series battery pack 38, no error is accumulated, and precise voltage adjustment can be performed.

Here, FIGS. 7 and 8 show a case where the first and second embodiments are generalized and applied to an assembled battery having an n (n is a natural number) series configuration. That is, the ith (1 <i <n)
The connection points on the positive and negative sides of the unit cell Ci are represented by Jci, Jci-1, and
The connection point of the corresponding voltage dividing resistors Ri and Ri-1 is represented by Jri, Jri-1
As a connection point Jci,
The potential of Jci-1 is Eci, Eci-1, and the potentials of the connection points Jri, Jri-1 are Eri, Eri-1.

Then, regarding the unit cell Ci, the partial pressure point J
A comparator that outputs a high-level signal when the potential of ri is higher than the potential of the connection point Jci outputs CPiH. Conversely, a high-level signal is output when the potential of the connection point Jci is higher than the potential of the voltage dividing point Jri. The comparator to be used is CPi L.
Assuming that the average voltage of the unit cell C obtained by the voltage dividing resistor R is VM and the terminal voltage of the unit cell Ci is Vi, each value has the relationship of the equation (7). Vi = Eci-Eci-1 VM = Eri-Eri-1 (7)

Accordingly, the condition for judging that Vi> VM, that is, the condition for turning on the switch SWi of the discharge circuit corresponding to the unit cell Ci is as follows: (Eci ≧ Eri) · (Eci−1 <Eri−1 + (Eci> Eri) · (Eci-1 ≦ Eri−1) (8), and the output condition of the comparator CP satisfying the condition (8) is CPi H CPi L as shown in FIG. CPi-1H CPi-1LL × H ×× H × L (9) In equation (8), the symbol “•” indicates a logical AND, and the symbol “+” indicates a logical OR.

For example, looking at the correspondence of the first formulas (8) and (9), at least that the comparator CPi-1 H is "H" means that the condition (Eci-1 <Eri-1) itself is not satisfied. And that at least the comparator CPi H is "L" is a negation of the condition (Eci <Eri), which means the condition (Eci ≧ Eri). The fact that the comparators CPi H and CPi L are both “L” means a condition (Eci = Eri).

As described above, even if the battery pack has a multi-series configuration in which n is several tens, for example, the first and nth
For the unit cells C1 and Cn, the comparator C
When the output levels of P1L and CPn H are each "H", the switches SW1 and SWn of the corresponding discharge circuit are turned on, and the ith unit cell Ci from the negative side in the middle between them. When the output condition of the comparator CP is satisfied as shown in the equation (8), the logic circuit section may be configured to turn on the switch SWi of the corresponding discharge circuit.

(Third Embodiment) FIG. 9 shows a third embodiment of the present invention. As described above, the present invention can theoretically be applied to any number of series batteries. However, in actuality, there is a problem such as the withstand voltage of the element to be used. Therefore, when the unit cell is a lithium battery having a cell voltage of about 3.6 V, an assembled battery of about 4 to 5 series is configured as one unit. Is considered preferable.

Therefore, in the third embodiment, as in the second embodiment, a battery pack 38 having a four-series configuration is provided with a voltage adjusting mechanism including a discharging circuit 33, a voltage dividing circuit 40 and a logic circuit unit 47. One battery module 48 is provided. And
By connecting 20 battery modules 48 in series, the cell voltage of the unit cell 21 of the lithium battery is 3.6V.
A driving battery 49 of an HEV which has a voltage of about 300 V with × 80 batteries was constructed.

The voltage regulator of the conventional configuration shown in FIG. 12 is applied to the driving battery 49, and the unit cell 2 in FIG. 12 is replaced by a battery module 48. That is, each battery module 4
In 8, the operation of the built-in logic circuit 47 automatically corrects the variation in terminal voltage among the four unit cells 21. Therefore, the MPU 7 can treat the battery module 48 as one cell.

According to the third embodiment configured as described above, the MPU 7 periodically measures the terminal voltages of the twenty battery modules 48 with the voltage detectors 4, and the multiplexer 5 and the A / D converter 6 , The voltage of the driving battery 49 formed by connecting substantially 80 unit cells 21 in series can be adjusted by one MPU 7. Therefore, unlike the past, a plurality of MPUs
Since there is no need to use the device, the cost of the apparatus can be greatly reduced.

(Fourth Embodiment) FIG. 10 shows a fourth embodiment of the present invention. The same parts as those of the second embodiment are denoted by the same reference numerals, and the description thereof will be omitted. explain. Voltage dividing circuit (voltage dividing means) 40 'of the fourth embodiment
Are divided from the voltage dividing circuit 40 of the second embodiment by the small voltage dividing resistors 23b,
24b and 25b are deleted.

The inverting and non-inverting input terminals of the differential amplifier (potential difference amplifying means, potential comparing means) 50 (1)
The output terminals are connected to terminals Jc1 and Jr1, respectively.
(Instead of terminal Jc1 of the second embodiment) Comparator 27
H and 27L are connected to the non-inverting and inverting input terminals. Further, the resistance 57 (1) inserted into the inverting input terminal of the differential amplifier 50 (1) and the resistance 58 (1) connected between the inverting input terminal and the output terminal are differential. It is provided for determining the amplification factor of the amplifier 50 (1).

A resistor 51 is connected between terminals Jc2 and Jc0.
H, a series circuit of diodes 52H and 52L, and a resistor 51L is connected, and a cathode of the diode 52H and an anode (common connection point) of 52L are connected to a terminal Jc1. The inverting input terminal of the comparator 27H is connected to the anode of the diode 52H, and the non-inverting input terminal of the comparator 27L is connected to the cathode of the diode 52H.

Similarly, a differential amplifier (potential difference amplifying means, potential comparing means) 50 (2) is arranged between the terminals Jc2 and Jr2 and the comparators 28H and 28L. Comparison means) 50 (3)
Are connected to terminals Jc3 and Jr3 and comparators 41H and 41L.
And is located between. A resistor 53H, diodes 54H and 54L, and a resistor 5 between the terminals Jc3 and Jc1.
A 3L series circuit is connected, and a series circuit of a resistor 55H, diodes 56H and 56L, and a resistor 55L is connected between the terminals Jc4 and Jc2. Other configurations are the same as those of the second embodiment.

Next, the operation of the fourth embodiment will be described. For example, the differential amplifier 50 (1) has a potential difference Vd1 between the potential Er1 at the terminal Jr1 and the potential Ec1 at the terminal Jc1.
(= Eri−Eci) and outputs the amplified signal α · Vd1 to the comparators 27H and 27L. Comparator 27
H indicates that the level of the amplified signal α · Vd1 is the diode 52H
Is higher than the forward voltage VF, that is, when .alpha..Vd1> VF, "H" is output.

The comparator 27L outputs the amplified signal α
When the level of Vd1 is negative (that is, Eri <Eci) and its absolute value is higher than the forward voltage VF of the diode 52L, that is, when | α · Vd1 |> VF (Vd1 <0), “ H ”is output. Further, the differential amplifier 50
The logic circuits 47 (not shown in FIG. 10) operate similarly for (2) and 50 (3) for the corresponding potentials.
The output signals of the comparators 27H to 41L are logically synthesized as in the second embodiment.

That is, as in the second embodiment, the small voltage dividing resistor 23
b, 24b and 25b, the comparators 28H-4
When 1L performs the potential comparison, there is a problem that it is difficult to stabilize the comparison operation because the resistance value actually changes due to a temperature change of the operating environment and the like.

On the other hand, according to the fourth embodiment, the difference Vd between the potential on the battery pack 38 side and the potential on the voltage dividing circuit 40 'side is amplified by the differential amplifier 50 and the comparators 28H to 4H are used.
1L, the comparators 28H to 41L output the level of the amplified signal α · Vd to the diodes 52, 5 having good stability.
Since the comparison is made with the reference voltage created by using the forward voltage VF of 4,56, the level of the terminal voltage Ec of the unit cell 21 and the average voltage VM can be more reliably determined, and the operation stability can be improved. Can be improved.

(Fifth Embodiment) FIGS. 11 to 13 show a fifth embodiment of the present invention. The same parts as those of the fourth embodiment are denoted by the same reference numerals, and description thereof will be omitted. Only the parts will be described. In the fifth embodiment, between the terminal Jc1 and the resistor 57 (1), between the terminal Jc2 and the resistor 57 (2),
Between terminal Jc3 and resistor 57 (3), terminal Jc4 and terminal Jr4
And fuses (path cutoff means) 59 (1),
59 (2), 59 (3) and 59 (4) are inserted.

A series circuit of a resistor 60 and a thermistor (temperature detecting means) 61 and a series circuit of resistors 63 and 64 are provided between the terminal Jr4 and a common connection point of the fuse 59 (3) and the resistor 57 (3). Is connected. The common connection point of the resistor 60 and the thermistor 61 is connected to the inverting input terminal of a comparator (temperature comparison means) 62, and the common connection point of the resistors 63 and 64 is connected via a resistor 65 to the non-inverting input terminal of the comparator 62. Connected to terminal. The output terminal of the comparator 62 is connected to its own non-inverting input terminal via a resistor 66, and is connected to the IH of a logic circuit (discharge control means) 67 instead of the logic circuit 47.
Connected to BT terminal.

The thermistor 61 is a negative thermistor whose resistance increases as the temperature decreases. The voltage applied to the inverting input terminal of the comparator 62 is
If the inter-terminal voltage of 1 (4) is constant, it is determined by the ratio of the resistance values of the resistor 60 and the thermistor 61. As an example,
The voltage between terminals of the unit cell 21 (4) is 4.0 V, the resistance is 6
If the resistance values of 0, 63 and 64 are 150 kΩ, the reference voltage applied to the non-inverting input terminal of the comparator 62 is 2.0V. When the temperature becomes lower than −30 ° C. (reference temperature), the resistance value of the thermistor 61 becomes 150 k.
Select one with characteristics of Ω or more. The resistance 51H,
51L, 53H, 53L, 55H, and 55L are not shown.

FIG. 12 shows an example of the configuration of the logic circuit section 67. That is, the logic circuit unit 67 adds the AND gates 68 (1), 68 (2), 6 to the logic circuit unit 47.
8 (3) and 68 (4). These A
One input terminal of the ND gate 68 is connected to the IHBT terminal, and the AND gates 68 (1), 68 (2), 68
The other terminals of (3) and 68 (4) are connected to the comparator 27
L terminal, the output terminal of the OR gate 36, the output terminal of the OR gate 46, and the output terminal of the comparator 41H. And AND gates 68 (1) to 6 (6)
The output terminals of 8 (4) are switches 35 (1) to 35 (35).
(4) are connected to the on / off control terminals, respectively.

Next, the operation of the fifth embodiment will be described with reference to FIG. FIG. 13 shows the truth values of the logic circuit section 67. When the voltage across the thermistor 61 is lower than the reference voltage applied to the non-inverting input terminal, the output terminal of the comparator 62 becomes high level “H”, and when the voltage across the thermistor 61 is higher than the reference voltage. , The output terminal goes low.

Therefore, when the ambient temperature detected by the thermistor 61 exceeds -30 ° C., the IHBT terminal of the logic circuit 67 becomes “H”, and the ambient temperature becomes −3 ° C.
When the temperature is 0 ° C. or lower, the IHBT terminal becomes “L”. That is, as shown in FIG. 13, if the ambient temperature exceeds −30 ° C. and the IHBT terminal is “H”, the switches 35 (1) to 35 (1)
The on / off control of 35 (4) is performed in exactly the same manner as in the case of the second embodiment shown in FIG. And the ambient temperature is -30
° C or lower and the IHBT terminal is “L”, the switches 35 (1) to 35 (4) are all turned off regardless of the output state of the comparators 27, 28, 41, and each unit cell 21 ( The discharges of 1) to 21 (4) are prohibited.

This control is performed for the following reason. That is, HEVs and the like are assumed to travel in various environments, but the ambient temperature in a cold region or the like is −30 ° C.
In a low-temperature environment as described below, the unit cell 21
May have an extremely large internal resistance. When the unit cell 21 is discharged in such a state, a large voltage drop occurs due to the discharge. Therefore, when the voltage of a certain unit cell 21 falls below the minimum voltage at that time, the unit which does not need to be adjusted in voltage originally The voltage of the cell 21 may be adjusted.

That is, if a voltage drop occurs due to the discharge, the voltage between the terminals of the unit cell 21 decreases. However, if the voltage drop is too large, the voltage of the unit cell 21, which originally shows the lowest voltage, also drops, and the discharge occurs. The middle unit cell 21 becomes the apparent lowest voltage cell. Then, the voltage of the other unit cells 21 is adjusted with the target unit cell 21 being discharged as a target, and the other unit cells 21 are discharged to the original lowest voltage cells that should not be discharged. As a result, the minimum voltage further decreases, the other unit cells 21 are adjusted to the target voltage and discharged, the adjustment operation is continued, and the
8 will lower the overall voltage. Therefore, when the ambient temperature falls below −30 ° C., the discharge of the unit cell 21 is prohibited.

For example, it is assumed that the HEV is running and a break occurs for some reason in the vicinity of the unit cell 21 (3) while the charging or discharging operation is being performed on the battery pack 38. I do. Then, an electromotive force corresponding to the total voltage of the assembled battery 38 (the sum of the voltages of the unit cells 21) is generated between the disconnection points Jc2 and Jc3 due to an inductance component of an inverter circuit or the like connected to the assembled battery 38, for example. Occurs.

When an electromotive force is generated between the terminals Jc2 and Jc3, a large current tries to flow into the voltage regulator via the fuses 59 (2) and 59 (3) and the respective discharge paths. When the fuses 59 (2) and 59 (3) are blown, the path is cut off.

As described above, according to the fifth embodiment, the ambient temperature is detected by the thermistor 61, and the ambient temperature is set to -30.
When the temperature falls below ° C., the logic circuit 67
, The unit cells 21 (1) to 21 (4)
Of the unit cell 2 in a low temperature environment
In the case where the internal resistance of the unit cell 21 becomes extremely large, the discharge is suppressed, so that the voltage of the unit cell 21 which does not need to be adjusted is originally required.
Can be avoided.

According to the fifth embodiment, the terminals Jc1 to Jc
Since the fuses 59 (1) to 59 (4) were inserted between c4 and the resistors 57 (1) to 57 (3) and the terminal Jr4, respectively, any one of the unit cells 21 was disconnected. Even if a high voltage is generated at both ends of the broken portion, the fuse 59 is blown to cut off the discharge path, so that the voltage regulator connected to the battery pack 38 is broken or burnt by the high voltage and large current. Can be protected from Conversely, if a short circuit occurs on the voltage regulator side due to, for example, the intrusion of foreign matter or a decrease in insulation, the fuse 5
9 (1) to 59 (4) can protect the battery pack 38 side.

(Sixth Embodiment) FIG. 14 shows a sixth embodiment of the present invention. The same parts as those of the fifth embodiment are denoted by the same reference numerals, and description thereof will be omitted. explain. In the sixth embodiment, a reference voltage Vref of 1.5 V is supplied to the inverting input terminal of a comparator (voltage comparing means) 62a instead of the comparator 62, instead of the common connection point of the resistor 60 and the thermistor 61 in the fifth embodiment. The positive terminal of the constant voltage source 69 to be supplied is connected, and the negative terminal of the constant voltage source 69 is connected to the fuse 59 (3) and the resistor 5.
7 (3).

In this case, since the resistors 63 and 64 equally divide the voltage between the terminals of the unit cell 21 (4), the comparator 62a determines whether the voltage between the terminals of the unit cell 21 (4) is supplied to the non-inverting input terminal. The voltage Vc, which is a half of the voltage, is compared with a reference voltage Vref supplied to the inverting input terminal. Here, the reference voltage Vref of 1.5 V is obtained by dividing the lower limit voltage of the unit cell 21 to 3.0 V by dividing the voltage of the resistors 63 and 64 by the dividing ratio 1 / 1.5.
2 is set.

The output terminal of the comparator 62a goes high when the voltage Vc is higher than the reference voltage Vref, and goes low when the voltage Vc is lower than the reference voltage Vref. Other configuration is 5th
This is the same as the embodiment.

Next, the operation of the sixth embodiment will be described. As described above, the voltage adjusting device of the present invention
The adjustment is performed so that the terminal voltages of the other unit cells 21 are adjusted to the lowest level among the terminal voltages of the unit cells 21. Therefore, assuming that any one of the unit cells 21 in the battery pack 38 is short-circuited for some reason and its terminal voltage is significantly lower than the lower limit voltage that can be used, other sound unit cells according to the voltage may be used. There is a possibility that even the terminal voltage of 21 may be adjusted to be lower than the lower limit voltage that can be used.

Therefore, in the sixth embodiment, in order to prevent such a situation from occurring, the comparator 62a uses the lower limit voltage Vc between the terminals of the unit cell 21 (4) applied to the non-inverting input terminal. When the voltage falls below 3.0 V, a low-level signal is applied to the IHBT terminal of the logic circuit section 67 to prevent the unit cell 21 from discharging.

As described above, according to the sixth embodiment, the resistance 6
3 and 64, the voltage V between terminals of the unit cell 21 (4)
is detected, and when the terminal voltage Vc falls below the lower limit voltage that can be used, the discharge of the unit cell 21 is prohibited by the comparator 62a and the logic circuit unit 67. Therefore, even if a short circuit occurs in any of the unit cells 21, In addition, it is possible to prevent the voltage of the other unit cells 21 from being significantly reduced.

The present invention is not limited to the embodiments described above and shown in the drawings, and the following modifications or extensions are possible. In the second embodiment, two NOTs
Instead of using the gates 32 and 42, as shown in FIG. 15, an AND gate 70 having a negative logic input is used, and the output terminal of the AND gate 70 is connected to the AND gates 31 and 4.
3 may be commonly connected. In such a configuration, the logical condition of the unit cell 21 (2) relating to the deformed portion satisfies the condition that the positive terminal voltage Ec2 is substantially equal to the divided potential Er2 (Ec2 = Er2), and When the divided potential Er1 is higher than the terminal voltage Ec1 on the negative electrode side (Ec1 <
In Er1), it is determined that the terminal voltage V2 is higher than the average voltage. For unit cell 21 (3),
The terminal voltage Ec2 on the negative electrode side is substantially equal to the divided potential Er2 (E
c2 = Er2) and the positive terminal voltage Ec3 is higher than the divided potential Er3 (Ec3> Er3).
Then, it is determined that the terminal voltage V3 is higher than the average voltage. Further, the same applies to the logic synthesis of the output signals of the comparators CPi, CPi-1 and CPi + 1 in the case of the n-series configuration shown in FIG. With such a configuration, the number of gates can be reduced by commonality, particularly when discrete elements are used in the logic circuit section in a multi-series configuration.

The unit cell is not limited to a lithium battery, but can be similarly applied to a lead battery or a nickel-based battery. It is not necessary to adjust the voltage for all the unit cells constituting the assembled battery, and the voltage may be adjusted for only a specific one of the unit cells or for a specific plurality of the unit cells. The present invention is not limited to the electric vehicle and the HEV, but may be applied to any device using a battery configured by connecting a plurality of unit cells in series. In the sixth embodiment,
The reference voltage Vref is set to the upper limit voltage of the adjusting operation (for example, 4.0
V), the inverting input terminal and the non-inverting input terminal of the comparator 62a are exchanged, or
The output signal of 2a may be inverted by a NOT gate. With such a configuration, the following operation and effect can be obtained. That is, factors that cause the voltage of each unit cell 21 to vary include the variation in the full charge capacity in addition to the variation in the remaining capacity described above. In the case of a lithium battery, since the voltage of the battery has a unique correlation with the state of charge, that is, the ratio between the remaining capacity and the full charge capacity, if the full charge capacity is different even if the remaining capacity is equal, the voltage varies, The magnitude of the variation increases as the remaining capacity increases. In such a case, even if it is not necessary to equalize the voltages of the unit cells 21, the amount of power discharged due to the voltage adjustment operation is wasted energy. Therefore, by setting the upper limit of the voltage adjustment operation by the reference voltage Vref, unnecessary voltage adjustment operation due to the variation in the full charge capacity is suppressed.
Useless energy consumption can be suppressed.

Further, two voltage comparators are prepared, one for the upper limit voltage and the other for the lower limit voltage.
Then, these output signals are ANDed (O of negative logic input / output
R) The upper and lower limits of the voltage adjustment operation are determined by giving the signal to the IHBT terminal of the logic circuit section 67 via the gate.
The voltage adjustment operation can be performed only in a limited voltage (remaining capacity) range. This is because, in a battery such as a driving battery of an HEV, in which charging and discharging are performed with an intermediate remaining capacity as a center, the voltage can be constantly adjusted with the remaining capacity near the center, and output (discharge) and regeneration ( The unit cell 21 can be used in a state in which the balance is maintained. The temperature detecting means and the temperature comparing means centered on the comparator 62 in the fifth embodiment, and the voltage detecting means and the voltage comparing means centered on the comparator 62a in the sixth embodiment may be simultaneously arranged. In that case, each output signal of the comparators 62 and 62a may be applied to the IHBT terminal of the logic circuit section 67 via an AND gate. The path cutoff means is not limited to the fuse 59. For example, a part having a reduced width dimension is provided for a part of a wiring pattern on a substrate serving as a discharge path, and the part is burned out when an overcurrent flows. It may be something that has been done.

[Brief description of the drawings]

FIG. 1 is an electrical configuration diagram showing a first embodiment when the present invention is applied to an assembled battery having a three-series configuration.

FIG. 2 is a diagram showing truth values of a logic circuit unit;

FIG. 3 is a diagram illustrating an example of a change in each terminal voltage when a variation in terminal voltage of a unit cell is adjusted (part 1);

FIG. 4 is a diagram corresponding to FIG. 3 (part 2);

FIG. 5 is a view corresponding to FIG. 1, showing a second embodiment in which the present invention is applied to a battery pack having a four-series configuration;

FIG. 6 is a diagram corresponding to FIG. 2;

FIG. 7 is a diagram corresponding to FIG. 1 when the present invention is applied to an assembled battery having an n-series configuration.

FIG. 8 is a diagram corresponding to FIG. 2;

FIG. 9 is a diagram showing a third embodiment in which the present invention is applied to a drive battery of a hybrid electric vehicle.

FIG. 10 is a view corresponding to FIG. 5, showing a fourth embodiment of the present invention;

FIG. 11 is a view corresponding to FIG. 5, showing a fifth embodiment of the present invention.

FIG. 12 illustrates an example of a detailed configuration of a logic circuit unit.

FIG. 13 is a diagram corresponding to FIG. 2;

FIG. 14 is a view corresponding to FIG. 5, showing a sixth embodiment of the present invention.

FIG. 15 is a diagram corresponding to FIG. 5 showing a modification.

FIG. 16 is a diagram corresponding to FIG. 9 showing a conventional technique.

FIG. 17 is a diagram corresponding to FIG. 16 when a plurality of unit cells are modularized.

FIG. 18 is a diagram corresponding to FIG. 1 showing another conventional technique.

[Explanation of symbols]

21 is a unit cell (lithium battery), 22 is an assembled battery, 2
3, 24, 25 are resistors, 26 is a voltage dividing circuit (voltage dividing means),
27H, 27L, 28H and 28L are comparators (potential comparison means), 33 is a discharge circuit (discharge control means), 37
Is a logic circuit section (discharge control means), 38 is an assembled battery, 39 is a resistor, 40 and 40 'are voltage dividing circuits (voltage dividing means), 41H
And 41L are comparators (potential comparison means), 47 is a logic circuit section (discharge control means), 49 is a driving battery,
0 is a differential amplifier (potential difference amplifying means, potential comparing means), 5
9 is a fuse (path breaking means), 61 is a thermistor (temperature detecting means), 62 is a comparator (temperature comparing means),
62a is a comparator (voltage comparing means), 63 and 64
Is a resistor (voltage detection means), 67 is a logic circuit part (discharge control means), Jc1, Jc2, Jc3, Jci-1, Jci are connection points, J
r1, Jr2, Jr3, Jri-1, and Jri indicate partial pressure points.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02J 7/02 H02J 7/02 H (72) Inventor Tetsuya Nagata 1-1-1, Showa-cho, Kariya-shi, Aichi Stock F term in company DENSO (reference) 2G016 CA03 CB06 CB11 CB12 CC01 CC04 CC12 CD01 CD02 CD03 CD04 CD06 CD14 2G035 AA01 AA16 AB03 AC01 AC16 AC18 AD02 AD03 AD04 AD10 AD11 AD20 AD23 AD27 AD45 5G003 BA03 CC04 DA04 DA13 FA04 GC06 5 FF42 FF44 5H115 PG04 PI16 QN12 TI05 TO05 TR19 TU16 TU17

Claims (8)

[Claims] An assembled battery formed by connecting a plurality of unit cells each composed of a secondary battery in series, voltage dividing means for dividing a terminal voltage of the assembled battery according to the number of the unit cells, Potential comparing means for comparing the potential of a specific connecting point among the connecting points between the plurality of unit cells with the potential of the voltage dividing point divided by the voltage dividing means corresponding to the connecting point; Temperature detecting means for detecting a temperature; temperature comparing means for comparing an ambient temperature detected by the temperature detecting means with a preset reference temperature; and the specific connection based on a comparison result by the potential comparing means. When it is determined that the terminal voltage of the unit cell corresponding to the point is higher than the average voltage, control is performed to discharge the unit cell, and based on the comparison result by the temperature comparing means, the ambient temperature is lower than the reference temperature. Voltage regulator of the battery pack, characterized in that a discharging control means for inhibiting that the discharge of the unit cells determined to have become. 2. An assembled battery formed by connecting a plurality of unit cells each formed of a secondary battery in series, voltage dividing means for dividing a terminal voltage of the assembled battery according to the number of the unit cells, Potential comparing means for comparing the potential of a specific connecting point among the connecting points between the plurality of unit cells, and the potential of the voltage dividing point divided by the voltage dividing means corresponding to the connecting point, An inter-terminal voltage detecting means for detecting an inter-terminal voltage of at least one of the plurality of unit cells; and comparing the inter-terminal voltage detected by the inter-terminal voltage detecting means with a preset reference voltage. A voltage comparing unit, based on a comparison result by the potential comparing unit, when it is determined that a terminal voltage of a unit cell corresponding to the specific connection point is higher than an average voltage, control is performed to discharge the unit cell; And said Based on the comparison result by the pressure comparing means, the voltage regulator of the assembled battery voltage between the terminals, characterized in that prohibiting discharge of the unit cells when it is determined that falls below the reference voltage. 3. An assembled battery formed by connecting a plurality of unit cells each composed of a secondary battery in series, voltage dividing means for dividing a terminal voltage of the assembled battery according to the number of the unit cells, Potential comparing means for comparing the potential of a specific connecting point among the connecting points between the plurality of unit cells, and the potential of the voltage dividing point divided by the voltage dividing means corresponding to the connecting point, An inter-terminal voltage detecting means for detecting an inter-terminal voltage of at least one of the plurality of unit cells; and comparing the inter-terminal voltage detected by the inter-terminal voltage detecting means with a preset reference voltage. A voltage comparing unit, based on a comparison result by the potential comparing unit, when it is determined that a terminal voltage of a unit cell corresponding to the specific connection point is higher than an average voltage, control is performed to discharge the unit cell; And said Based on the comparison result by the pressure comparing means, the voltage regulator of the assembled battery voltage between the terminals, characterized in that prohibiting discharge of the unit cells determines that equal to or greater than the reference voltage. 4. An assembled battery formed by connecting a plurality of unit cells each composed of a secondary battery in series, voltage dividing means for dividing a terminal voltage of the assembled battery according to the number of the unit cells, Potential comparing means for comparing the potential of a specific connecting point among the connecting points between the plurality of unit cells with the potential of the voltage dividing point divided by the voltage dividing means corresponding to the connecting point; When it is determined that the terminal voltage of the unit cell corresponding to the specific connection point is higher than the average voltage based on the comparison result by the potential comparing unit, the control unit includes a discharge control unit that controls the unit cell to discharge. A voltage regulating device for a battery pack, wherein path interrupting means for interrupting the discharge path when an overcurrent flows in the discharge path of the unit cell is arranged on the discharge path in the vicinity of the unit cell. 5. A method of dividing a terminal voltage of a battery pack formed by connecting a plurality of unit cells each composed of a secondary battery in series according to the number of unit cells by a voltage dividing means. The potential of a specific connection point among the connection points between them is compared with the potential of the voltage dividing point divided by the voltage dividing means corresponding to the connection point by the potential comparison means, and the comparison by the potential comparison means is performed. Based on the result, when it is determined that the terminal voltage of the unit cell corresponding to the specific connection point is higher than the average voltage, the unit cell is discharged, and the ambient temperature detected by the temperature detecting means and the preset reference temperature And comparing the ambient temperature with the reference temperature, based on the comparison result by the temperature comparing means, and prohibiting the discharge of the unit cell. Voltage adjustment method. 6. A plurality of unit cells composed of a plurality of unit cells connected in series and a terminal voltage of an assembled battery divided by a voltage dividing means according to the number of the unit cells. The potential of a specific connection point among the connection points between them is compared with the potential of the voltage dividing point divided by the voltage dividing means corresponding to the connection point by the potential comparison means, and the comparison by the potential comparison means is performed. Based on the result, when it is determined that the terminal voltage of the unit cell corresponding to the specific connection point is higher than the average voltage, the unit cell is discharged, and the terminals of at least one of the plurality of unit cells are connected. The voltage is compared with a preset reference voltage by a voltage comparing means. Based on a result of the comparison by the voltage comparing means, when it is determined that the inter-terminal voltage has become equal to or less than the reference voltage, discharging of the unit cell is prohibited. Voltage adjusting method of an assembled battery according to claim Rukoto. 7. A terminal voltage of an assembled battery formed by connecting a plurality of unit cells each composed of a secondary battery in series according to the number of the unit cells by a voltage dividing means. The potential of a specific connection point among the connection points between them is compared with the potential of the voltage dividing point divided by the voltage dividing means corresponding to the connection point by the potential comparison means, and the comparison by the potential comparison means is performed. Based on the result, when it is determined that the terminal voltage of the unit cell corresponding to the specific connection point is higher than the average voltage, the unit cell is discharged, and the terminals of at least one of the plurality of unit cells are connected. A voltage is compared with a preset reference voltage by a voltage comparing means. Based on a result of the comparison by the voltage comparing means, when it is determined that the inter-terminal voltage is equal to or higher than the reference voltage, discharging of the unit cell is prohibited. Voltage adjusting method of an assembled battery according to claim Rukoto. 8. A plurality of unit cells, each comprising a plurality of unit cells connected in series, and a terminal voltage of an assembled battery is divided according to the number of the unit cells by a voltage dividing means. The potential of a specific connection point among the connection points between them is compared with the potential of the voltage dividing point divided by the voltage dividing means corresponding to the connection point by the potential comparison means, and the comparison by the potential comparison means is performed. Based on the result, when it is determined that the terminal voltage of the unit cell corresponding to the specific connection point is higher than the average voltage, the unit cell is discharged, and when an overcurrent flows through the discharge path of the unit cell, each unit cell is discharged. A voltage adjusting method for an assembled battery, wherein said discharge path is interrupted by a path interrupting means arranged on a near side.