JP3768376B2 - Electric double layer capacitor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric double layer capacitor device having a plurality of electric double layer capacitors connected in series, and in particular, a hybrid vehicle configured to assist driving of an engine output by a driving force of a motor during acceleration or the like. The present invention relates to an electric double layer capacitor device suitable for use as a power source for the motor.
[0002]
[Prior art]
Electric double layer capacitors take advantage of simple physical changes that do not depend on chemical reactions, so that their lifetime is semi-permanent and they can be charged with a large current in a very short time. Thus, it has been proposed to be used as a power source for an assist motor of a hybrid vehicle.
By the way, since the electric double layer capacitor has a low withstand voltage, that is, the absolute rated voltage is as low as about 3 V, it is common to use a plurality of electric double layer capacitors connected in series to increase the rated voltage. When using a large-capacity electric double layer capacitor, it will deteriorate if an overvoltage is applied across the electric double layer capacitor, thus preventing an overvoltage from being applied across the electric double layer capacitor. Therefore, it can be said that it is necessary to add a control circuit for preventing overvoltage to each of the plurality of electric double layer capacitors connected in series.
[0003]
In addition, it is a well-known fact that there is a variation in the voltage between the terminals of each of the plurality of electric double layer capacitors connected in series due to the self-discharge property of the electric double layer capacitor. The use of a plurality of double layer capacitors results in insufficient performance of the individual electric double layer capacitors. That is, when a plurality of electric double layer capacitors connected in series are charged and discharged, an equivalent current flows through each electric double layer capacitor. Therefore, for example, during charging, electric double layer capacitors having different initial voltages (initial values of capacitor terminal voltages) at the start of charging are charged with the same current, and the voltage between terminals of each electric double layer capacitor is increasing. Is the same.
[0004]
For this reason, the electric double layer capacitor having a high initial voltage is quickly overcharged, and the electric double layer capacitor having a low initial voltage has a lower charging voltage at the same time than the electric double layer capacitor having a high initial voltage. . As a result, the energy obtained from a plurality of series-connected electric double layer capacitors charged with different inter-terminal voltages (initial voltages) at the start of charging is equal to the same number of electricity with the inter-terminal voltages aligned at the start of charging. It will be less than the energy chosen from the double layer capacitor.
[0005]
Therefore, if monitoring is performed so that no overvoltage is applied to each of the plurality of electric double layer capacitors connected in series and charging is controlled so that there is no variation in the voltage between the terminals, the plurality of electric double layer capacitors connected in series are Although the performance of the electric double layer capacitor device can be exhibited, there is a problem that this control is difficult and the device becomes expensive.
Therefore, in order to sufficiently exhibit the performance of a low-cost electric double layer capacitor device, control has been conventionally performed so as to eliminate variations in the voltage between terminals of each electric double layer capacitor.
[0006]
The configuration of a conventional electric double layer capacitor device is shown in FIG. In the figure, for the sake of convenience of explanation, only a single electric double layer capacitor is shown, but actually, a plurality of electric double layer capacitors are connected in series, and a control circuit is provided for each electric double layer capacitor. In the figure, between the terminals of the electric double layer capacitor 1, a control transistor 2, a voltage comparison unit 3 for comparing the reference voltage and the voltage between the terminals of the electric double layer capacitor 1, and the voltage between the terminals of the electric double layer capacitor 1. A control circuit including a reference voltage generation unit 4 for generating a reference voltage from is provided.
[0007]
The control transistor 2 is turned on and off based on the comparison result of the voltage comparison unit 3, and controls the voltage between the terminals of the electric double layer capacitor. In this case, by setting the reference voltage several percent lower than the overvoltage value of the electric double layer capacitor, the transistor 2 is turned on only when the voltage between the terminals of the electric double layer capacitor 1 exceeds the reference voltage. Control is performed so that an overvoltage is not applied between the terminals of the capacitor 1. Here, the electric double layer capacitor with excellent self-discharge characteristics is more likely to exceed the reference voltage for the same charge compared to other electric double layer capacitors, so the voltage across the terminals of the electric double layer capacitor over time The variation of can also be reduced.
[0008]
[Problems to be solved by the invention]
However, in the conventional electric double layer capacitor device described above, the reference voltage that is compared with the voltage across the terminals of the electric double layer capacitor by the voltage comparison unit 3 is set almost equal to the overvoltage of the electric double layer capacitor. Unless the voltage between the terminals of the electric double layer capacitor reaches the vicinity of the overvoltage, the variation in the voltage between the terminals in the plurality of electric double layer capacitors connected in series cannot be converged.
In addition, in order to prevent an overvoltage from being applied between the terminals of the electric double layer capacitor, the amount of current corresponding to the charging voltage to be charged is further increased after the voltage between the terminals of the electric double layer capacitor reaches the reference voltage. It is necessary to set so as to bypass to the transistor 2 side.
[0009]
Therefore, it is an absolute condition that the transistor 2 itself can absorb the current flowing through the electric double layer capacitor 1 and the power loss is within the collector loss. When the amount of current to be bypassed is large, it may be necessary to select a Darlington connection of a plurality of transistors as a bypass transistor and add a heat radiating fin. One of the provided control circuits becomes very expensive.
[0010]
Also, if the number of electric double layer capacitors used is increased in order to obtain more energy in the electric double layer capacitor device, the price for the number of control circuits corresponding to the increased number of electric double layer capacitors used increases. It will be.
The present invention has been made in view of such circumstances, and in obtaining a balance between voltages of a plurality of electric double layer capacitors connected in series, generation of useless power loss can be prevented and is inexpensive. An object is to provide an electric double layer capacitor device.
[0011]
[Means for Solving the Problems]
  In order to achieve the above-mentioned object, the invention according to claim 1 is to discharge a plurality of electric double layer capacitors connected in series and connected in parallel to each of the plurality of electric double layer capacitors. pluralDischargeAnd a voltage between terminals of each of the plurality of electric double layer capacitors.Lower than the overvoltage of the electric double layer capacitorA plurality of voltage comparison means for comparing with the first set voltage;Control means for controlling the operation and stop of the control operation of the discharge means based on the comparison outputs of the plurality of voltage comparison means, the control means,Corresponding to the electric double layer capacitor in which the voltage between the terminals exceeds the first set voltage based on the comparison output of the plurality of voltage comparison meansDischargemeansActivating the control action ofElectric double layer capacitor device that equalizes the voltage between terminals of each electric double layer capacitorInThe control means is configured to charge the plurality of electric double layer capacitors.During the charging of the plurality of electric double layer capacitors, until the voltage between the terminals of any of the plurality of electric double layer capacitors reaches a second set voltage that is greater than the first set voltage,The pluralityDischargeThe control operation of the means is stopped.
[0012]
  According to the electric double layer capacitor device of claim 1, by the control means,When charging the plurality of electric double layer capacitors, the voltage between terminals of any one of the plurality of electric double layer capacitors is larger than the first set voltage during charging of the plurality of electric double layer capacitors. Since the control operation of the plurality of discharge means is stopped until the second set voltage is reached,When obtaining the balance of the voltage between the terminals of the plurality of electric double layer capacitors connected in series, it is possible to prevent useless power loss due to bypassing during charging.
[0013]
  According to a second aspect of the present invention, in the electric double layer capacitor device according to the first aspect of the present invention, the control means is any one of the plurality of electric double layer capacitors during charging of the plurality of electric double layer capacitors. When the voltage between the terminals of the electric double layer capacitor reaches a second set voltage that is larger than the first set voltage, charging of the plurality of electric double layer capacitors is stopped, and the plurality of electric double layer capacitors are The plurality of discharge so as to be in a dischargeable stateDischargemeansActivating the control actionIt is characterized by that.
  According to a third aspect of the present invention, in the electric double layer capacitor device according to the second aspect, the second set voltage detects a state in which the voltage between the terminals of the electric double layer capacitor has reached an overvoltage. It is a voltage.
  According to a fourth aspect of the present invention, in the electric double layer capacitor device according to any one of the first to third aspects, the discharging means is a switch connected in parallel to each of the plurality of electric double layer capacitors. And a bypass resistor.
[0014]
  Claim 23According to the electric double layer capacitor device described in item 1, the control means is configured such that the voltage across the electric double layer capacitor of any of the plurality of electric double layer capacitors is the first voltage during charging of the plurality of electric double layer capacitors. When the second set voltage greater than the set voltage is reached, charging of the plurality of electric double layer capacitors is stopped, and the plurality of electric double layer capacitors are set in a dischargeable state.DischargemeansActivating the control actionSince it did in this way, in addition to the effect acquired by the invention of Claim 1, the damage of the electric double layer capacitor by the voltage more than an overvoltage being applied between the terminals of an electric double layer capacitor is prevented. Can do.
  According to the electric double layer capacitor device of the fourth aspect, the amount of current flowing through the bypass transistor (switch) when the electric current is bypassed from the electric double layer capacitor is reduced, so that the bypass transistor is inexpensive. An inexpensive electric double layer capacitor device can be obtained.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of an electric double layer capacitor device according to an embodiment of the present invention. In the figure, an electric double layer capacitor device according to an embodiment of the present invention includes electric double layer capacitors 10-1, 10-2,... Connected in series, and each electric double layer capacitor, for example, Both terminals of the electric double layer capacitor 10-1 are connected to each other via a PNP transistor 12-1 as a switching element and a bypass resistor 14-1.
[0016]
Further, a reference voltage VREF1 (bypass start voltage) for starting bypass from the inter-terminal voltage VC (capacitor voltage) of the electric double layer capacitor 10-1 in parallel between both terminals of the electric double layer capacitor 10-1. The reference voltage generator 18-1 to be generated is compared with the inter-terminal voltage VC of the electric double layer capacitor 10-1 and the reference voltage VREF1, and the voltage corresponding to the comparison result is output to the base of the PNP transistor 12-1. The comparison unit 16-1 is connected. The reference voltage VREF1 generated by the reference voltage generator 18-1 is set to, for example, 2.5V, which is several percent lower than the overvoltage (eg, 3V) of the electric double layer capacitor 10-1. The voltage comparison unit 16-1 turns on the PNP transistor 12-1 when the inter-terminal voltage VC of the electric double layer capacitor 10-1 exceeds the reference voltage VREF1 (2.5V), and the electric double layer capacitor 10-1 1 is discharged through the bypass resistor 14-1.
[0017]
The above configuration is the same for the other electric double layer capacitors 10-2,. PNP transistors 12-1, 12-2, ..., bypass resistors 14-1, 14-2, ..., voltage comparators 16-1, 16-2, ..., reference voltage generators 18-1, 18-2, ... Constitutes a bypass part of the electric double layer capacitor device. Here, in order to increase the ability to converge the voltage variation between terminals of each electric double layer capacitor, select a bypass resistor with a small resistance value, and increase the absolute rating of the switching transistor that allows current to flow through the bypass resistor. This is possible (in this case, the bypass current increases), but it becomes difficult to realize the electric double layer capacitor device at a low price.
Therefore, in the present embodiment, on the contrary, a resistor having a large resistance value is selected as a bypass resistor so as to reduce the burden on the switching transistor constituting the drive circuit.
[0018]
Further, a reference voltage of a level different from that of the reference voltage generator 18-1, that is, an electric double layer capacitor, is provided between both terminals of each electric double layer capacitor of the electric double layer capacitor device, for example, the electric double layer capacitor 10-1. A reference voltage generator 20 that generates a reference voltage VREF2 (for example, set to 3 V) for detecting a state in which the voltage between both ends of 10-1 has reached an overvoltage from the voltage between terminals of the electric double layer capacitor 10-1. -1 and a voltage comparison unit 22-1 for comparing the reference voltage VREF2 generated by the reference voltage generation unit 20-1 and the inter-terminal voltage VC of the electric double layer capacitor 10-1 are connected in parallel.
[0019]
The electric double layer capacitor device further controls the PNP transistors 12-1, 12-2,... To balance the voltage between the terminals of each electric double layer capacitor, and outputs the voltage comparison unit 22-1. It has a photocoupler 24-1 that outputs to the controller 30 and other circuit units, and a photocoupler 26-1 that outputs a control signal from the controller 30 to the base of the PNP transistor 12-1. The output sides of the photocouplers 24-1, 24-2,... Are connected in common and are connected to the input side of the controller 30. Similarly, the input sides of the photocouplers 26-1, 26-2,... Are connected in common and connected to the output side of the controller 30.
[0020]
The voltage comparison unit 22-1 compares the inter-terminal voltage VC of the electric double layer capacitor 10-1 with the reference voltage VREF2 generated by the reference voltage generation unit 20-1, and the inter-terminal voltage VC reaches the reference voltage VREF2. At the moment of entering the overvoltage region, an overvoltage detection signal, which is a comparison output, is output to the controller 30 via the photocoupler 24-1. Upon receiving this overvoltage detection signal, the controller 30 recognizes that the voltage VC between the terminals of any of the electric double layer capacitors 10-1, 10-2,... A control signal (charging stop signal) for stopping the charging operation is output to the charging unit. At this time, as will be described later, the output of the control signal (charging signal) for turning off each of the PNP transistors 12-1, 12-2,.
[0021]
In addition, when the electric double layer capacitor of the electric double layer capacitor device is in a charged state, the controller outputs a control signal (charging signal) to the base of each PNP transistor 12-1, 12-2,. The charging current to each electric double layer capacitor 10-1, 10-2,... Is not bypassed.
The configuration of the circuit unit including the reference voltage generation unit 20-1, the voltage comparison unit 22-1, the photocoupler 24-1, and the photocoupler 26-1 is the same for the other electric double layer capacitors 10-2,. . Reference voltage generators 20-1, 20-2, ..., voltage comparators 22-1, 22-2, ..., photocouplers 24-1, 24-2, ..., photocouplers 26-1, 26-2, ... Constitutes an overvoltage detector of the electric double layer capacitor device. Here, the PNP transistors 12-1, 12-2,... Are the current control means of the present invention, the voltage comparison units 16-1, 16-2,. These correspond to the control means.
[0022]
The control operation of the electric double layer capacitor device having the above configuration will be described with reference to the flowcharts shown in FIGS. The electric double layer capacitor device according to the present embodiment will be described as being used as a power source for a drive assist motor for a hybrid vehicle. The control routine shown in FIG. 2 is started at regular intervals by a timer interrupt, and is executed by the controller 30. When power is supplied to each part from the battery by operating the engine key, the control routine shown in FIG. 2 is started, and the terminals of the electric double layer capacitors 10-1, 10-2,. A voltage check is performed. That is, the voltage comparison units 16-1, 16-2,... Perform a magnitude comparison between the inter-terminal voltage VC and the reference voltage VREF1 (2.5 V) in each electric double layer capacitor (step 100).
[0023]
Next, at step 101, it is determined whether VC <VREF1. If it is determined in step 101 that VC ≧ VREF1, the process proceeds to step 104. On the other hand, if it is determined that VC <VREF1, whether the vehicle is decelerating, in other words, the motor for assisting driving of the engine performs a regenerative operation to function as a generator, and the electric double layer capacitor Is determined to be in a charged state (step 102). If it is determined that the vehicle is not decelerating, that is, the vehicle is traveling (the electric double layer capacitor is being discharged), the routine proceeds to step 108.
[0024]
Further, when it is determined in step 102 that the vehicle is decelerating, the electric double layer capacitors 10-1, 10-2,... From the controller 30 via the photocouplers 26-1, 26-2,. A control signal for forcibly turning off these transistors is output to the respective PNP transistors 12-1, 12-2,. As a result, during the charging period, the electric double layer capacitors 10-1, 10-2,... Bypass operation is stopped.
It is determined whether or not the terminal voltage VC and the reference voltage VREF1 in each electric double layer capacitor are VC ≧ VREF1 (step 103).
[0025]
If it is determined in step 103 that VC <VREF1, the process returns to step 100. If it is determined in step 103 that VC ≧ VREF1, it is determined whether or not each electric double layer capacitor is being charged (step 104). When it is determined in step 104 that charging is not in progress, a control signal for forcibly turning off the PNP transistors 12-1, 12-2,... Is not output from the controller 30 to the bases of these transistors. In step 108, the corresponding PNP transistor is turned on by the output from the corresponding voltage comparison unit for the electric double layer capacitor satisfying VC ≧ VREF1, and the voltage between the terminals of the electric double layer capacitor is discharged through the bypass resistor. (Steps 108 and 109).
[0026]
Next, in step 110, it is determined whether or not VC <VREF1 for each electric double layer capacitor. If any of the plurality of electric double layer capacitors is VC ≧ VREF1, the process returns to step 108, and step 108 Repeat the process of ~ 110. When the inter-terminal voltage VC of all the electric double layer capacitors becomes VC <VREF1, a comparison signal for turning off the transistor is output to each PNP transistor as a corresponding switching element from each starch pressure comparison unit. Therefore, the bypass operation of each electric double layer capacitor is stopped (step 111).
On the other hand, when it is determined in step 104 that each electric double layer capacitor is being charged, it is determined whether or not there is an electric double layer capacitor whose inter-terminal voltage VC becomes VC ≧ VREF2 (step 105). ). If the determination in step 105 is negative, the process returns to step 104 and the same process is performed.
[0027]
If the determination in step 105 is affirmative, that is, if it is determined that there is an electric double layer capacitor in which the inter-terminal voltage VC becomes VC ≧ VREF2, the corresponding electric double layer capacitor, for example, an electric double layer If the inter-terminal voltage VC of the capacitor 10-1 becomes VC ≧ VREF2, an overvoltage detection signal is transmitted from the voltage comparison unit 22-1 provided corresponding to the electric double layer capacitor 10-1 via the photocoupler 24-1. The controller 30 recognizes that there is an electric double layer capacitor in which VC ≧ VREF2, that is, the voltage between the terminals has reached the overvoltage region, and the electric double layer capacitors 10-1, 10-2. ,..., A control signal for stopping the charging operation for a charging unit (not shown)charging(Stop signal) is output (step 106).
[0028]
Next, the controller 30 outputs the electric double layer capacitors 10-1, 10-2,... Via the photocouplers 26-1, 26-2,. The PNP transistors 12-1, 12-2,... Provided forcibly turn off these transistors and stop the output of control signals (charge signals) that prohibit the bypass operation. As a result, each of the PNP transistors 12-1, 12-2,... Can be driven to an on / off state by the outputs of the corresponding voltage comparison units 16-1, 16-2,. It becomes a state and shifts to the discharge mode (step 107).
[0029]
Next, the process proceeds to step 108, the bypass process of steps 108 to 111 is performed, and this process ends.
The control routine described above is repeated and executed by a timer interrupt, whereby the terminal voltage value of each electric double layer capacitor changes in the direction of convergence and finally becomes uniform.
[0030]
FIG. 4 shows a state in which the inter-terminal voltage VC of each electric double layer capacitor in the electric double layer capacitor device mounted on the hybrid vehicle by the above process changes with time while the hybrid vehicle is traveling. For convenience of explanation, FIG. 4 shows a change state in the terminal voltage VC of three electric double layer capacitors connected in series and having different initial voltages. In the figure, in section T1 (t0 ≦ t <t1), the charging capacity of the electric double layer capacitor is much larger than the bypass capacity, so the voltage VC between the electric double layer capacitors A and B is in the bypass region, that is, Even when the voltage range of VREF1 ≦ VC <VREF2 is reached, the bypass effect is hardly observed with respect to the voltage transition of the inter-terminal voltage VC.
[0031]
For this reason, the voltage VC between the terminals of the electric double layer capacitor reaches the overvoltage region VC ≧ VREF2 with the passage of time, and deteriorates if the charging state continues as it is. Will end up. Therefore, as described above, an overvoltage detection signal is output from the voltage comparison unit in the overvoltage detection unit to the controller 30, and the controller 30 performs control to stop charging based on this signal. That is, in FIG. 4, since the inter-terminal voltage VC of the electric double layer capacitor A reaches the overvoltage region at time t1, charging to the electric double layer capacitors A, B, C is stopped.
[0032]
In the present invention, bypassing the charging current during the charging period of the electric double layer capacitor causes wasteful current to flow through the bypass unit (switching element and bypass resistor) and consumes wasteful power. As much as possible, charging current is not bypassed during charging. Thus, the voltage control of the electric double layer capacitor device with less power loss is realized by stopping the function of the bypass unit at the time of charging where the bypass effect cannot be obtained and driving the bypass unit only at the time of discharging.
[0033]
In addition, since the overvoltage detection unit determines that the voltage VC between the terminals of the electric double layer capacitor A has reached the overvoltage (VREF2) at time t2 in FIG. 4, charging is stopped in the period T2 (t1 ≦ t <t3). The electric double layer capacitors A, B, and C are in a discharge state. The change in the voltage VC between the terminals of the electric double layer capacitor C is due to load driving (running), and the change in the voltage VC between the terminals of the electric double layer capacitors A and B is due to load driving and a bypass effect. It can be seen that the change in the voltage VC between the terminals of the electric double layer capacitors A and B has a larger voltage fluctuation per unit time than that of the electric double layer capacitor C.
[0034]
In addition, the voltage VC between the terminals of the electric double layer capacitor B is changed to the discharge only for driving the load from time t2 because the discharge is out of the bypass region at time t2 due to discharge. It has become. By repeating cycles such as the periods T1 and T2 in FIG. 4, the values of the inter-terminal voltages in the plurality of electric double layer capacitors having different initial voltages converge to a predetermined value, that is, align.
[0035]
As described above, according to the electric double layer capacitor device according to the embodiment of the present invention, it is prohibited to bypass the charging current when charging a plurality of electric double layer capacitors. In addition, when obtaining the balance of the voltages between the terminals of the plurality of electric double layer capacitors, it is possible to prevent generation of useless power loss due to bypassing during charging.
[0036]
Further, according to the electric double layer capacitor device according to the embodiment of the present invention, when a current is bypassed from the electric double layer capacitor, a resistor having a large resistance value is bypassed so as to reduce the amount of current flowing to the bypass transistor. Since it is used with a resistor, an inexpensive transistor can be used as a bypass switching element, and an inexpensive electric double layer capacitor device can be obtained.
[0037]
  Furthermore, according to the electric double layer capacitor device according to the embodiment of the present invention, when the voltage between the terminals of any of the plurality of electric double layer capacitors reaches a set voltage (overvoltage),The charging of the plurality of electric double layer capacitors is stopped, and the plurality of electric double layer capacitors are brought into a dischargeable state.Because I tried to control, ElectricIt is possible to prevent the electric double layer capacitor from being damaged by applying a voltage having a level higher than the overvoltage between the terminals of the air double layer capacitor.
[0038]
【The invention's effect】
    According to the electric double layer capacitor device of claim 1, by the control means,When charging the plurality of electric double layer capacitors, the voltage between terminals of any one of the plurality of electric double layer capacitors is larger than the first set voltage during charging of the plurality of electric double layer capacitors. Since the control operation of the plurality of discharge means is stopped until the second set voltage is reached,When obtaining a balance between the voltages of a plurality of electric double layer capacitors connected in series, it is possible to prevent generation of useless power loss due to bypassing during charging.
[0039]
According to the electric double layer capacitor device of the first aspect, the bypass transistor can be made inexpensive by reducing the amount of current flowing through the bypass transistor when the current is bypassed from the electric double layer capacitor. An electric double layer capacitor device that can be used and is inexpensive is obtained.
[0040]
    Claim 23According to the electric double layer capacitor device according to claim 1, in the electric double layer capacitor device according to claim 1, the control means is one of the plurality of electric double layer capacitors during charging of the plurality of electric double layer capacitors. When the voltage between the terminals of the electric double layer capacitor reaches a second set voltage that is larger than the first set voltage, charging of the plurality of electric double layer capacitors is stopped, and the plurality of electric double layer capacitors are The plurality of discharge so as to be in a dischargeable stateDischargemeansActivating the control actionSince it did in this way, in addition to the effect acquired by the invention of Claim 1, the damage of the electric double layer capacitor by the voltage more than an overvoltage being applied between the terminals of an electric double layer capacitor is prevented. Can do.
  According to the electric double layer capacitor device of the fourth aspect, the amount of current flowing through the bypass transistor (switch) when the electric current is bypassed from the electric double layer capacitor is reduced, so that the bypass transistor is inexpensive. An inexpensive electric double layer capacitor device can be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an electric double layer capacitor device according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a control operation of a controller in the electric double layer capacitor device shown in FIG. 1;
FIG. 3 is a flowchart showing a control operation of a controller in the electric double layer capacitor device shown in FIG. 1;
FIG. 4 is a characteristic diagram showing a change state of the voltage between terminals of each electric double layer capacitor with time in the electric double layer capacitor device.
FIG. 5 is a block diagram showing a basic configuration of a conventional electric double layer capacitor device.
[Explanation of symbols]
10-1, 10-2 Electric double layer capacitor
12-1, 12-2 PNP transistor (current control means)
14-1, 14-2 Bypass resistance
16-1, 16-2, 22-1, 22-2 Voltage comparison unit (voltage comparison means)
18-1, 18-2 20-1, 20-2 Reference voltage generator
24-1, 24-2 26-1, 26-2 Photocoupler
30 controller (control means)

Claims (4)

A plurality of electric double layer capacitors connected in series;
A plurality of discharging means connected in parallel to each of the plurality of electric double layer capacitors to discharge each electric double layer capacitor;
A plurality of voltage comparison means for comparing a voltage between terminals of each of the plurality of electric double layer capacitors with a first set voltage lower than an overvoltage of the electric double layer capacitor ;
Control means for controlling the operation and stop of the control operation of the discharge means based on the comparison output of the plurality of voltage comparison means,
The control means is
Based on the comparison outputs of the plurality of voltage comparison means, the control means of the discharge means corresponding to the electric double layer capacitor whose inter-terminal voltage exceeds the first set voltage is activated , In the electric double layer capacitor device that makes the voltage between terminals uniform,
In the charging of the plurality of electric double layer capacitors, the control means is configured such that the voltage between the terminals of any one of the plurality of electric double layer capacitors is the first voltage during charging of the plurality of electric double layer capacitors. The electric double layer capacitor device is characterized in that the control operation of the plurality of discharging means is stopped until a second set voltage higher than the set voltage is reached . The control means sets the voltage between the terminals of any of the plurality of electric double layer capacitors to a second set voltage that is higher than the first set voltage during charging of the plurality of electric double layer capacitors. When it reaches, the charging of the plurality of electric double layer capacitors is stopped, and the control operation of the plurality of discharging means is operated so that the plurality of electric double layer capacitors can be discharged. Item 2. The electric double layer capacitor device according to Item 1.   3. The electric double layer capacitor device according to claim 2, wherein the second set voltage is a voltage for detecting a state in which an inter-terminal voltage of the electric double layer capacitor has reached an overvoltage.   The electric double layer capacitor device according to any one of claims 1 to 3, wherein the discharging means is a switch and a bypass resistor connected in parallel to each of the plurality of electric double layer capacitors.

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