JP2003070178A - Charging state adjusting device and charging state detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging state adjusting device which has a simple constitution and can hold a uselessly consumed current minimum, and a charging state detection device with a simple constitution. SOLUTION: A standard current generation part 7 generates a reference current Ii which corresponds to a double end voltage VO of a cell pack 1, and hence, to an average cell voltage Vave (=VO/n), a control circuit Ji generates a reference signal Vm from the reference current Ii using a resistor Rc and a divided signal Vp by dividing a cell voltage VCi of a unit cell Ci by resistors Ra, Rb. The resistors Ra to Rc and resistances Rx, Ry which determine the magnitude of the reference current Ii are chosen so that VCi>Vave if Vp>Vm. When the divided signal Vp is larger than the reference signal Vm, namely the cell voltage VCi is larger than the average cell voltage Vave, a control signal Si from a comparator CM becomes a high level, turns a transistor Td of a discharge circuit Di on and discharges the unit cell Ci.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a state-of-charge adjusting device and a state-of-charge detecting device for adjusting or detecting the state of charge of a large number of unit cells connected in series to form an assembled cell.

[0002]

2. Description of the Related Art Conventionally, as a power source for driving a motor of an electric vehicle (EV) or a hybrid electric vehicle (HEV), an assembled cell in which a plurality of unit cells including a secondary battery and an electric double layer capacitor are connected in series has been used. Are known.

The unit cells that make up such a set cell are
Since there are variations in capacity, internal resistance, self-discharge, etc., repeated charging / discharging of assembled cells causes variations in the voltage across each unit cell (hereinafter referred to as “cell voltage”). When such cell voltage variations occur, the entire charge / discharge of the assembled cell is prevented so that individual unit cells do not exceed the preset allowable voltage range and become overcharged or overdischarged. Need to control. However, in this case, the larger the variation in cell voltage between the unit cells, the narrower the operating voltage range of the assembled cell as a whole, and there is a problem in that the performance of the assembled cell cannot be sufficiently brought out.

On the other hand, there is known a technique for equalizing the cell voltages among the unit cells forming the assembled cell. As one example thereof, Japanese Patent Laid-Open No. 6-253463 discloses
A microcomputer that connects a bypass circuit (discharge circuit) composed of a resistor and a switch to each unit cell in parallel, detects the cell voltage of each unit cell, and controls the switch of the bypass circuit based on the detection result (hereinafter referred to as “microcomputer”). When a cell voltage varies among the unit cells that form the assembled cell, the bypass circuit corresponding to the unit cell having the higher voltage is operated to discharge the unit cell or A technique for reducing the voltage difference between unit cells by shunting the charging current is disclosed.

In Japanese Patent Laid-Open No. 11-332115, a bypass circuit formed by connecting a Zener diode and a resistor in series is connected in parallel to each unit cell, and the cell voltage of the unit cell exceeds the Zener voltage. In this case, there is disclosed a technique of adjusting the state of charge of the unit cell by discharging the unit cell via a bypass circuit.

[0006]

However, in the case of the former,
Since it is necessary to detect the cell voltages of all the unit cells that form the assembled cell, it is necessary to provide the control unit with the same number of voltage detection circuits as the unit cells. In addition, the number of cells that can be handled by one CPU constituting the microcomputer is limited to about 10 to 20 cells in consideration of withstand voltage, insulation and controllability. For this reason, when applied to an assembled cell in which several tens to several hundreds of unit cells are connected in series, such as when used as a power source for an EV or an HEV, the entire assembled cell is divided into a plurality of cell groups and each cell group is divided. It is necessary to provide a CPU for each of them and to provide a higher-level CPU that controls these CPUs to adjust the entire assembled cell.
Thus, not only a large number of voltage detection circuits are required, but also a CPU for processing the detection result of the voltage detection circuit.
In addition, a large number of expensive parts such as a multiplexer and an AD converter for loading the detection result into the CPU are required, which causes a problem that the device becomes large and expensive.

On the other hand, in the latter case, the necessary discharge must be completed within a short time when the voltage of the unit cell exceeds the Zener voltage. Therefore, in order to obtain a sufficient voltage adjusting capability, the current capacity is required. There is a problem that the device becomes expensive because the bypass circuit must be configured by using the large parts. In addition, in order to adjust the state of charge, it is necessary to increase the amount of charge to the assembled cell so that the cell voltage of each unit cell exceeds the Zener voltage, and as a result, the charge flows through the bypass circuit and is wasted. If the Zener voltage is set to a high value in order to bring out the problem of increasing the current or the battery performance sufficiently, the unit cell with the larger cell voltage will always have a cell voltage near the Zener voltage. There is also a problem that the deterioration of the cell is likely to proceed.

Further, in this device, when it is necessary to detect a unit cell in an overcharged or overdischarged state,
There was also a problem that a dedicated detection circuit had to be provided separately. In order to solve the above-mentioned problems, the present invention provides a state-of-charge adjusting device that can minimize the wasted current with a simple structure, and a unit cell that configures an assembled cell with a simple structure. An object of the present invention is to provide a state-of-charge detecting device that can detect the state of charge with high accuracy.

[0009]

According to another aspect of the present invention, there is provided a state-of-charge adjusting device which is provided for each unit cell that constitutes an assembled cell, and which comprises a voltage dividing signal generating means. , The voltage across the target unit cell to be controlled is divided, and a divided voltage signal having a potential higher than the potential of the negative terminal of the target unit cell is generated by the divided voltage.

Further, the reference current generating means generates a reference current corresponding to the voltage across the assembled cells, and based on the reference current, the reference signal generating means is an average voltage which is an average voltage of the unit cells constituting the assembled cells. A reference signal having a potential higher than the potential of the negative terminal of the target unit cell is generated by the reference voltage proportional to the cell voltage.

However, in the reference signal generating means, the ratio of the reference voltage to the average cell voltage is set so as to match the voltage dividing ratio in the voltage dividing signal generating means. That is, the magnitude relationship between the average cell voltage and the voltage across the target unit cell is made to match the magnitude relationship between the reference signal and the divided voltage signal.

Then, the comparing means compares the reference signal generated by the reference signal generating means with the divided voltage signal generated by the divided voltage signal generating means, and according to the comparison result, the divided voltage from the reference signal is divided. When the signal has a higher potential, that is, when the voltage across the target unit cell is greater than the average cell voltage,
The discharging means conducts electrical connection between both ends of the target unit cell to discharge the target unit cell.

As described above, according to the state-of-charge adjusting device of the present invention, the unit cells exceeding the preset voltage (for example, the upper limit voltage) are not discharged, but the unit cells exceeding the average cell voltage are discharged. Therefore, if the cell voltage between the unit cells fluctuates even a little, the equalization operation for eliminating this fluctuation is immediately performed, so that a sufficient equalization ability can be obtained even if the discharge current is small.

Further, the state-of-charge adjusting device of the present invention is configured without using expensive components such as a voltage detection circuit for detecting the voltage across the unit cell, a microprocessor, a multiplexer and an AD converter. Moreover, since an electronic component having a small current capacity can be used as the electronic component forming the discharging means, the device can be made compact and inexpensive.

Further, according to the state-of-charge adjusting device of the present invention, the state of charge is surely adjusted even if the assembled cells are not charged more than necessary, so that wasteful power consumption is minimized. You can keep it to the limit. Next, in the state-of-charge adjusting device according to the second aspect, the switching unit switches the supply destination of the comparison result in the comparing unit to either the discharging unit or the output terminal to the outside according to the switching signal from the outside.

According to the state-of-charge adjusting device of the present invention configured as described above, not only the unit cells are equalized but the state of charge of the target unit cell (exceeding the average cell voltage is exceeded by operating the switching signal. It is possible to detect (whether or not) via the output terminal. Further, as described in claim 3, either one of the upper limit voltage and the lower limit voltage of the allowable voltage range of the unit cell is set as the limit voltage, and the switching means supplies the comparison result in the comparison means to the output terminal signal side. When set, the reference current generating means is a reference current corresponding to the voltage across the assembled cell, instead of the reference current corresponding to the voltage across both ends of the assembled cell obtained when it is assumed that all the unit cells constituting the assembled cell are at the limit voltage. A reference current according to the voltage may be generated.

In this case, if the upper limit voltage is set as the limit voltage, it can be detected via the output terminal whether or not the voltage across the target unit cell is in an overcharged state larger than the upper limit voltage, while the lower limit voltage is set. If it is set as the limit voltage, it can be detected via the output terminal whether or not the voltage across the target unit cell is in an over-discharged state smaller than the lower limit voltage. That is,
According to the present invention, it is possible to detect the overcharged state or the overdischarged state of the target unit cell by only slightly improving the reference current generating means.

Still further, as described in claim 4, the reference current generating means can set the limit voltage to either the upper limit voltage or the lower limit voltage of the allowable voltage range of the unit cell according to a selection signal from the outside. By doing so, it is possible to detect both the overcharged state and the overdischarged state of the target unit cell by operating the selection signal.

By the way, since an electric vehicle, a hybrid electric vehicle, or the like is usually provided with a voltage detecting means for detecting the voltage across the assembled cell, in such a case, as described in claim 5, this voltage is used. The reference signal may be generated based on the voltage across the assembled cell detected by the detection means.

Further, in order to simplify the device structure,
As described in claim 6, it is desirable that the device is configured to receive power from the assembled cell that is the target of adjustment. Further, as the unit cell, for example, an electric double layer capacitor may be used as described in claim 7, or a lithium battery may be used as described in claim 8. Of course, capacitors and secondary batteries other than these may be used.

Since the electric double layer capacitor is originally excellent in durability, it is possible to further improve the reliability of the assembled cell by combining it with the state-of-charge adjusting device of the present invention, and at the same time, to improve the reliability of the assembled cell. You can maximize the performance. On the other hand, the lithium-based secondary battery is
Since the energy density is high and the output voltage is high, even if the same high voltage is obtained, an assembled cell having a large capacity can be constructed with a small number of cells, so that the assembled cell itself and the charge state adjusting device can be made compact and lightweight. .

Further, the state-of-charge adjusting device may be applied to the assembled cell for any purpose. For example, as described in claim 9, for driving an electric vehicle (EV) or a hybrid electric vehicle (HEV), or When applied to the assembled cell used as the power source for starting the engine, the reliability and durability of the EV or HEV can be improved.

Next, the charge state detecting device according to claim 10 is provided for each unit cell constituting the assembled cell, and the voltage dividing signal generating means divides the voltage across the target unit cell to be detected. Then, the divided voltage is generated and a divided voltage signal having a higher potential than the potential of the negative electrode terminal of the target unit cell is generated.

Further, the reference current generating means generates a reference current corresponding to the voltage across the assembled cell obtained when it is assumed that all the unit cells constituting the assembled cell are at the preset limit voltage, Based on the reference current, the reference signal generating means generates a reference signal having a potential higher than the potential of the negative terminal of the target unit cell by the reference voltage proportional to the limit voltage.

However, in the reference signal generating means, the ratio of the reference voltage to the limit voltage is set so as to match the voltage dividing ratio in the voltage dividing signal generating means. That is, the magnitude relationship between the limit voltage of the unit cell and the voltage across the target unit cell is made to match the magnitude relationship between the reference signal and the divided voltage signal.

Then, the comparing means compares the reference signal generated by the reference signal generating means with the divided voltage signal generated by the divided voltage signal generating means, and outputs the comparison result as a detection signal to the outside. To do. In the state-of-charge detection device of the present invention configured as described above, when the upper limit voltage is set as the limit voltage, whether the voltage across the target unit cell is in the overcharge state larger than the upper limit voltage via the output terminal. On the other hand, when the lower limit voltage is set as the limit voltage, it can be detected via the output terminal whether or not the voltage across the target unit cell is in an over-discharge state smaller than the lower limit voltage.
That is, according to the present invention, overcharge or overdischarge of a unit cell can be detected without using expensive parts such as a CPU and an AD converter.

Further, according to the eleventh aspect, the reference current generating means can set the limit voltage to either the upper limit voltage or the lower limit voltage of the allowable voltage range of the unit cell according to a selection signal from the outside. By doing so, it is possible to detect both overcharge and overdischarge of the target unit cell by operating the selection signal.

Needless to say, the configurations described in claims 6 to 9 may be applied to the charge state detecting device according to claims 10 and 11.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] FIG. 1 is a block diagram showing the entire configuration of the assembled cell system according to the first embodiment, and is used here as a power source for a motor for driving a hybrid vehicle (HEV) or for starting an engine.

As shown in FIG. 1, the assembled battery system according to the present embodiment includes an assembled cell 1 in which n unit cells C1 to Cn each composed of an electric double layer capacitor are connected in series, and each unit cell C1 to Cn. To control the operation of the discharge units D1 to Dn provided for each of the discharge units D1 to Dn and the discharge unit 3 composed of n discharge circuits D1 to Dn connected in parallel to each other. Control signals S1 to
For the control unit 5 including n control circuits J1 to Jn that generate Sn and the control circuit J1 to Jn, the voltage VO across the assembled cell 1, and thus the unit cell C1 that constitutes the assembled cell 1.
Average cell voltage Vave (= VO /
n), and a reference current generating unit 7 as a reference current generating unit that supplies the reference currents I1 to In having a magnitude corresponding to n).

The assembled cell 1 is connected to an electric motor that also serves as a motor and a generator via an inverter connected to the main power line L, and a control device (not shown) controls the running state of the vehicle and the assembled cell 1. Depending on the voltage at both ends (charge amount),
The starting and stopping of the electric motor and the operating direction of the inverter are controlled to charge and discharge the assembled cell 1.

Specifically, when the engine is running at a constant speed with good operating efficiency, the driving force of the engine is used for running. At this time, if the charge amount of the assembled cell 1 is insufficient,
The driving force from the engine is transmitted to the electric motor, the electric motor operates as a generator, and the electric power generated by the electric motor is set to be supplied to the assembled cell 1 through the inverter, and the assembled cell 1 is charged. To perform.

On the other hand, at the time of starting the engine with poor operating efficiency or at full acceleration, the electric power from the assembled cell 1 is supplied to the electric motor through the inverter, and the electric motor serves as a motor by the electric power supplied from the assembled cell 1. It is set to operate, and travels using the driving force from the electric motor.

Next, all the discharge circuits Di (i = 1 to n) have the same structure, and the bypass path connecting both ends of the unit cell C1 is connected to the control signal S from the control circuit Ji.
A transistor Td that turns on and off according to i, and a resistor Rd that limits the magnitude of the current that flows between the collector and emitter of the transistor Td, that is, the current that flows in the bypass path.
Consists of.

Each of the control circuits Ji has the same configuration, and has resistors Ra and Rb as voltage dividing signal generating means for dividing the voltage across the unit cell Ci and one end of which has a low potential of the unit cell Ci. A resistor Rc, which is connected to the side end and serves as a reference signal generating unit that converts the reference current Ii supplied from the reference current generator 7 into a reference signal that is a voltage signal, and a resistor Ra, Rb that divides the non-inverting input by resistors Ra and Rb. The divided voltage signal is applied, the reference signal generated by the resistor Rc is applied to the inverting input, and the output is supplied as the control signal Si to the discharge circuit Di.

Further, the reference current generator 7 is composed of a multi-output current mirror circuit, and has a transistor Tx and a resistor R.
A current corresponding to the voltage between both ends of the assembled cell 1 flows in a current path in which x and Ry are connected in series, and a reference current I of the same magnitude as this.
i is configured to flow in a current path in which a resistor Ri and a transistor Ti are connected in series.

Here, the resistance R which constitutes each control circuit Ji
a to Rc, and the resistors Rx that form the reference current generator 7,
A method of setting Ry and Ri will be described. In addition, the resistance value of each resistor is represented by using the same reference numeral for identifying the resistor. First, assuming that the collector-emitter voltage of the transistor Tx is Vce, the current I flowing through the resistors Rx and Ry.
x is represented by the equation (1) using the average cell voltage Vave (= VO / n).

Ix = (n · Vave−Vce) / (Rx + Ry) (1) Further, the collector current (ie, reference current) Ii of each transistor Ti forming the current mirror circuit together with the transistor Tx is equal to the current Ix, and n × Vave is Vce
If it is sufficiently large, equation (1) is approximately represented by equation (2).

Ii = Ix≈n · Vave / (Rx + Ry) (2) That is, the current Ix flowing through the resistors Rx and Ry, and thus the reference current Ii, has a magnitude substantially proportional to the average voltage Vave of the assembled cell 1. Then it can be considered. On the other hand, in the control circuit Ji, the voltage across the unit cell Ci (cell voltage) is V
Assuming Ci, the potential Vp of the divided voltage signal applied to the non-inverting input of the comparator CM is expressed by the equation (3).

Vp = VCi · Rb / (Ra + Rb) (3) Further, the reference voltage generated by the resistor Rc in accordance with the reference current Ii, that is, the potential Vm of the reference signal applied to the inverting input of the comparator CM is expressed by the formula (4). It is represented by. Vm = Rc.Ii = Rc.n.Vave / (Rx + Ry) (4) However, both Vp and Vm are potentials indicated with reference to the potential on the low potential side end of the unit cell Ci.

That is, the resistors Ra to Rc, Rx, Ry.
Is set to satisfy the relationship of the equation (5), Vp>
Vm and VCi> Vave have the same value. Rb / (Ra + Rb) = n.Rc / (Rx + Ry) (5) Therefore, the control signal Si output from the comparator CM
Becomes high level when the potential Vp of the divided signal is higher than the potential Vm of the reference signal (Vp> Vm), that is, when the cell voltage VCi is higher than the average cell voltage Vave (VCi> Vave).

The control signal Si turns on the transistor Td of the discharge circuit Di, so that the unit cell Ci is discharged. In this way, the unit cells exceeding the average cell voltage Vave are sequentially discharged, so that the cell voltages of all the unit cells C1 to Cn finally become equal to the minimum cell voltage among them. The adjustment operation continues until.

The resistance values Ra to Rc, Rx, Ry.
Is actually set such that the right side of equation (5) is slightly larger than the left side. That is, the discharge of the unit cell Ci is not started until the cell voltage VCi becomes larger than the average cell voltage Vave by ΔV represented by the equation (6).

[0044]

[Equation 1]

This is because the cell voltage VCi of the unit cell Ci which is being discharged by the discharge circuit Di is equal to the unit cell Ci.
The internal cell voltage Vave drops due to the internal resistance of the wire harness, the resistance of the wire harness, etc., and the average cell voltage Vave also drops to Vave '. Then, a unit cell having a cell voltage slightly lower than the original average cell voltage Vave may become higher than the apparent average cell voltage Vave ′ dropped due to the discharge. Since the unit cells that do not need to be discharged are discharged, the equalization operation may not converge.

In order to prevent such a situation, in any case, by setting the resistance value so that Vave-Vave '<ΔV, a dead zone is provided in the range of Vave to Vave + ΔV, and discharge is required. That is, it is possible to reliably prevent the discharge of the unit cells that do not exist and to ensure that the cell voltage equalizing operation converges.

Here, FIG. 2 is a graph showing a result obtained by simulation of how the cell voltage of each unit cell Ci changes due to the cell voltage adjusting (equalizing) operation in the assembled cell system of this embodiment. Is. However, the number n of unit cells constituting the assembled cell 1 is 10, the capacitance of each unit cell Ci is 100 [F], and the rated voltage is 2.0.
[V] and the resistance Rd of the discharge circuit Di was set to 200 [Ω]. That is, when the transistor Td was turned on, the discharge current flowing through the discharge circuit Di was set to about 10 [mA]. Further, ΔV obtained by the above equation (6)
Was set to 2 [mV].

As shown in FIG. 2, unit cells C1 to C10 are provided.
The equalization was started from the state (t = 0 [min]) in which each cell voltage VC of No. 2 varied in the range of 2.0 to 2.3 [V]. The cell voltage VC is set so that the unit cell C1 has the highest value, the cell voltage VC has the lowest value in the order of C2, C3, ..., And the unit cell C10 has the lowest value.

When the equalization is started, first, the unit cells C1 to C4 having a cell voltage higher than the average cell voltage are discharged, and as the average cell voltage is lowered by the discharge, the unit cells C5 to C9 are also discharged. The cell voltages of the unit cells C1 to C9 that are sequentially discharged and finally discharged are
When the cell voltage becomes substantially equal to the cell voltage of the unit cell C10, that is, the cell voltages VC1 to VC9 are ΔV greater than the cell voltage VC10.
At the time when the value has dropped to a large value (t = 47 [mi
n]), the discharge is completed, and thereafter the state is maintained.

As described above, according to the assembled cell system of this embodiment, the cell voltage VCi is the average cell voltage Vav.
By equalizing the cell voltages VC1 to VCn by discharging the unit cells Ci exceeding e, the equalizing operation is performed immediately if the cell voltages vary a little.
Even if the discharge current is small, a sufficient equalizing ability can be obtained, and the power wasted for adjustment can be minimized.

Further, the assembled cell system of this embodiment is configured without using expensive components such as a voltage detection circuit for detecting the cell voltages VC1 to VCn, a microprocessor, a multiplexer, and an AD converter. And
Moreover, as the resistor Rd and the transistor Td forming the discharge circuits D1 to Dn, those having a small current capacity can be used, so that the device can be made compact and inexpensive.

Furthermore, in the assembled cell system of this embodiment,
Using the current mirror circuit, the voltage VO across the assembled cell 1
(As a result, the reference current Ii corresponding to the average cell voltage Vave)
Is generated and converted into a reference signal using the resistor Rc, the resistors Rx and R forming the current mirror circuit are necessary when the signal level of the reference signal needs to be changed.
This can be easily handled by changing only y.

In this embodiment, the reference current is generated using the current mirror circuit. However, as shown in FIG. 3, the assembled cell voltage as a voltage detecting means for detecting the voltage VO across the assembled cell 1 is detected. When the detection circuit 11 is provided,
The detection result may be used to operate the current control circuit 13 including a constant current source to obtain the reference current.

Further, as the assembled cell voltage detection circuit 11,
Instead of using a unique one for the assembled cell system, a voltage detection circuit provided in the control device for controlling the charging / discharging of the assembled cell 1 may be used. [Second Embodiment] Next, a second embodiment will be described.

The assembled cell system of the present embodiment is different from that of the first embodiment only in part of the configuration, and therefore, the same components are designated by the same reference numerals, and the description thereof will be omitted. The part will be mainly described. As shown in FIG. 4, the assembled cell system of the present embodiment outputs a switching signal X and also a controller 1 that monitors detection signals (control signals) S1 to Sn from switch circuits SW1 to SWn described later.
5 and the supply destination of the control signal Si from the control circuit Ji according to the switching signal X from the controller 15
i or the controller 15, a signal switching unit 9 including a switch circuit SWi as a switching unit for switching to either i or the controller 15.
It has and. However, the controller 15 uses the assembled cell 1
It may also serve as a control device for controlling the charging and discharging of.

Further, the reference current generator 7a is the same as the reference current generator 7 of the first embodiment except that it has a constant current source CS and a switching signal X.
According to the above, either the resistor Ry or the constant current source CS is
Switch circuit S connected to the collector of the transistor Tx
It has a configuration in which Wx is added. However, switching signal X
If the switch circuit SWi selects the discharge circuit Di side, the switch circuit SWx selects the resistor Ry side if the switch circuit SWi selects the discharge circuit Di side, and if the switch circuit SWi selects the controller 15 side, the switch circuit SWi, SWx SWx operates so as to select the constant current source CS side.

Here, the constant current source CS is a switch circuit S.
It is assumed that Wx selects the resistor Ry side, and the voltage VO across the assembled cell 1 is n times the upper limit voltage VU of the allowable voltage range of the unit cell Ci, that is, all the unit cells C1.
It is configured to flow a constant current equal to the magnitude of the current Ix flowing through the transistor Tx when it is assumed that the cell voltage of ~ Cn is at the upper limit voltage VU.

In the assembled cell system of the present embodiment having such a configuration, the switch circuit S is activated by the switching signal X.
When Wi and SWx are set to select the discharge circuit Di side and the resistor Ry side, respectively, the operation is exactly the same as in the first embodiment. On the other hand, according to the switching signal X, the switch circuits SWi and SWx are on the controller 15 side,
When it is set to select the constant current source CS side, the reference current Ii corresponding to n times the upper limit voltage VU of the unit cell Ci.
Is supplied to each control circuit Ji.

Therefore, the potential Vm of the reference signal applied to the inverting input of the comparator CM is expressed by the equation (4a), and eventually, the upper limit voltage VU is used instead of the average cell voltage Vave.
Will be substituted. Vm = Rc.Ii = Rc.n.VU / (Rx + Ry) (4a) That is, Vp> Vm and VCi> VU have the same value, and therefore the control signal Si which is the output of the comparator CM. Becomes high level when the potential Vp of the divided signal is higher than the potential Vm of the reference signal (Vp> Vm), that is, when the cell voltage VCi is higher than the upper limit voltage VU (VCi> VU). Then, the control signal Si is supplied to the controller 15 as a detection signal via the switch circuit SWi.

As described above, according to the assembled cell system of the present embodiment, not only the same effects as those of the first embodiment can be obtained, but also the unit cell is detected based on the detection signals from the switch circuits SW1 to SWn. C1 to Cn are overcharged (V
It is possible to detect whether or not Ci> VU). Moreover, in order to detect such an overcharged state, only a small configuration such as the switch circuits SW1 to SWn, SWx and the constant current source CS needs to be added, and the device can be made highly functional without increasing its size. it can.

In this embodiment, the constant current source CS is
The constant current having a magnitude corresponding to the upper limit voltage VU of the allowable voltage range of the unit cell Ci is configured to flow, but instead, the constant current having a magnitude corresponding to the lower limit voltage VL of the allowable voltage range of the unit cell Ci flows. It may be configured as follows. In this case, V
Since p> Vm and VCi> VL have the same value, the control signal Si output from the comparator CM has the potential Vp of the voltage-divided signal equal to the potential Vm of the reference signal.
When it is smaller (Vp <Vm), that is, when the cell voltage VCi is larger than the lower limit voltage VL (VCi <VL), the level becomes low.

That is, based on the detection signals from the switch circuits SW1 to SWn, it is possible to detect whether or not the unit cells C1 to Cn are in the overdischarged state (VCi <VL). Further, the constant current source CS can switch and flow either a constant current according to the upper limit voltage VU or a constant current according to the lower limit voltage VL according to a selection signal (not shown) from the controller 15. You may comprise. In this case, it is possible to detect both the overcharged state and the overdischarged state of the unit cells C1 to Cn.

Further, in this embodiment, the unit cells C1 to C are
Although the equalization of n and the state detection are switched, the discharging unit 3 and the signal switching unit 9 are omitted, and the control unit 5 is omitted.
The output of is output to the controller as it is,
You may comprise as a state detection apparatus which detects only the state of a unit cell.

Further, in the first and second embodiments, the electric double layer capacitors are used as the unit cells C1 to Cn which form the assembled cell 1, but a secondary battery such as a lithium ion battery may be used. .

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a cell assembly system of a first embodiment.

FIG. 2 is a graph showing a result obtained by simulation of a change in cell voltage of each unit cell during the equalization operation.

FIG. 3 is an overall configuration diagram of an assembled cell system that is a modified example of the first embodiment.

FIG. 4 is an overall configuration diagram of an assembled cell system of a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Assembly cell, 3 ... Discharge part, 5 ... Control part, 7, 7a ... Reference current production | generation part, 9 ... Signal switching part, 11 ... Assembly cell voltage detection circuit, 13 ... Current control circuit, 15 ... Controller, C1-.
Cn ... Unit cell, CM ... Comparator, CS ... Constant current source, D1-Dn ... Discharge circuit, J1-Jn ... Control circuit, L
... Main power supply lines, Ra to Rd, Rx, Ry, R1 to Rn
... resistors, SW1 to SWn, SWx ... switch circuit, T
d, Tx, T1 to Tn ... Transistors

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5G003 AA01 BA03 CA11 CC02 FA06                 5H030 AA03 AA04 AS06 AS08 AS18                       BB23 DD08 FF41 FF51                 5H115 PA08 PA11 PG04 PI16 PO02                       PO11 PU01 PU21 QN02 SE06                       TI01 TI05 TR19 TU04 TU16                       TU17 TZ10

Claims (11)

[Claims] 1. A charge state adjusting device provided for each unit cell for adjusting the charge state of an assembled cell in which a plurality of chargeable / dischargeable unit cells are connected in series, which is a target unit to be controlled. A divided voltage signal generating means for generating a divided voltage signal having a potential higher than the potential of the negative terminal of the target unit cell by dividing the voltage across the cell, and a reference corresponding to the voltage across the assembled cell. A reference current generating means for generating a current, and the target unit corresponding to a reference voltage proportional to an average cell voltage which is an average voltage of the unit cells forming the assembled cell, based on the reference current generated by the reference current generating means. Reference signal generation that generates a reference signal having a potential higher than the potential of the negative terminal of the cell and that is set so that the ratio of the reference voltage to the average cell voltage matches the voltage division ratio in the voltage division signal generation means. means Comparing means for comparing the magnitude of the reference signal generated by the reference signal generating means with the divided voltage signal generated by the divided voltage signal generating means, and the reference signal according to the comparison result of the comparing means. Further, when the divided voltage signal has a higher potential, a discharging unit that conducts between both ends of the target unit cell and discharges the target unit cell, the charge state adjusting device comprising: 2. The switching means for switching the supply destination of the comparison result of the comparison means to either the discharging means or the output terminal to the outside according to a switching signal from the outside. The state-of-charge adjusting device described. 3. The upper limit voltage or the lower limit voltage of the unit cell is set as a limit voltage, and the reference current generating means is the switching means for supplying the comparison result in the comparing means to the output terminal signal side. When set to, characterized in that it generates a reference current according to the voltage across the group of cells obtained when it is assumed that all the unit cells constituting the group of cells are at a preset limit voltage. The charge state adjusting device according to claim 2. 4. The reference current generating means is capable of setting the limit voltage to either an upper limit voltage or a lower limit voltage of an allowable voltage range of the unit cell according to a selection signal from the outside. Item 3. The charge state adjusting device according to item 3. 5. The reference current generating means includes a voltage detecting means for detecting a voltage across the assembled cell, and generates the reference signal based on a detection result of the voltage detecting means. The state-of-charge adjusting device according to any one of claims 1 to 4. 6. The state-of-charge adjusting device according to claim 1, wherein the device receives power supply from an assembled cell that is an object of adjustment. 7. The state-of-charge adjusting device according to claim 1, wherein the unit cell is an electric double layer capacitor. 8. The state-of-charge adjusting device according to claim 1, wherein the unit cell is a lithium battery. 9. The cell assembly according to claim 1, wherein the assembled cell is provided for driving an electric vehicle or a hybrid electric vehicle or starting an engine.
The charge state adjusting device according to any one of the above. 10. A charge state detection device provided for each unit cell for detecting the charge state of an assembled cell in which a plurality of chargeable / dischargeable unit cells are connected in series, which is an object to be detected. A divided voltage signal generating means for generating a divided voltage signal having a potential higher than the potential of the negative terminal of the target unit cell by a divided voltage obtained by dividing the voltage across the unit cell, and all the units forming the assembled cell. Based on the reference current generated by the reference current generation means for generating a reference current according to the voltage across the assembled cell obtained when the cell is assumed to be at a preset limit voltage, Generating a reference signal having a higher potential than the potential of the negative terminal of the target unit cell by a reference voltage proportional to the limit voltage,
And a reference signal generating means set so that the ratio of the reference voltage to the limit voltage matches the voltage dividing ratio of the voltage dividing signal generating means, the reference signal generated by the reference signal generating means, and the dividing voltage. A charging state detection device comprising: a comparison unit that compares the magnitude of the divided voltage signal generated by the pressure signal generation unit with each other, and outputs the comparison result of the comparison unit to the outside as a detection signal. 11. The reference current generating means can set the limit voltage to either an upper limit voltage or a lower limit voltage of an allowable voltage range of the unit cell according to a selection signal from the outside. Item 10. The charge state detection device according to item 10.