JP2008061469A - Energy storage device using electric double-layer capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy storage device that uses an electric double-layer capacitor, capable of completely and safely performing equalizing charge, using a relatively simple circuit configuration. <P>SOLUTION: The device includes a capacitor bank 1 which is formed by connecting m units of electric double-layer capacitors in parallel and connecting them in series in n stages, an energy conversion device 2 which is connected to an AC power supply and can control rapid charging/discharging of the capacitor bank 1, an equalizing charge assist device 3 which applies anequalizing voltage to each series stage of the capacitor bank 1, and a voltage detecting device 5 which detects the voltage in each series stage of the capacitor bank 1. The capacitor bank 1 is charged by the energy conversion device 2, when all the detected values of the voltage detecting device 5 are a predetermined value or lower; and the capacitor bank 1 is charged by the equalizing charge assist device 3, when at least one of the detected values of the voltage detecting device 5 exceeds the predetermined voltage value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an energy storage device using an electric double layer capacitor having a capacitor bank in which a plurality of electric double layer capacitors are connected in series.

  A single electric double layer capacitor has a small capacity and low voltage of several μF and a rated voltage of about 2.5V. For this reason, when a capacity of several kVA or more is applied to an energy storage device or the like, a capacitor bank is constructed by connecting a large number of electric double layer capacitors having the same rated capacity and rated voltage in parallel and in series.

  On the other hand, since this electric double layer capacitor has a large capacity and internal impedance tolerance, when charging a capacitor bank all at once, or when rapid high-current charging / discharging is repeated, the charging voltage between capacitors does not increase. There was a problem that equality occurred.

  If the charging voltage is uneven among the individual capacitors, the entire capacitor bank cannot be fully charged, and the energy storage efficiency decreases. Since the stored energy of the capacitor is proportional to the square of the charging voltage, it is desirable to fully charge the charging voltage of the capacitor as much as possible. In addition, if some capacitors are charged to a voltage higher than the rated voltage, it may cause malfunctions such as leakage and damage of the capacitors, resulting in a problem that reliability as an energy storage device is lowered.

In order to solve the above problem, a proposal has been made to provide a control unit for equal charge for each series stage of the capacitor bank and control each series stage to have a predetermined voltage (for example, Patent Document 1). reference.).
Japanese Patent Laying-Open No. 2003-235173 (page 3-4, FIG. 4)

  In the method disclosed in Patent Document 1, the main charging circuit performs batch charging until the entire capacitor bank reaches a predetermined voltage value, and thereafter, each series stage is operated by an auxiliary charging control circuit provided in each series stage. The charging control is performed for each series stage so that the voltage of the above becomes a desired value.

  However, according to this method, since the switching voltage that determines the timing for switching from the main charging circuit to the auxiliary charging control circuit is detected by the voltage across the capacitor bank, the capacitor voltage of a specific series stage may be excessive in some cases. There was a fear. Further, since the auxiliary charging control circuit individually controls charging, there is a problem that the circuit configuration becomes complicated.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an energy storage device using an electric double layer capacitor that can be charged uniformly and safely with a relatively simple circuit configuration. And

  In order to achieve the above object, an energy storage device using an electric double layer capacitor according to the present invention includes n (n is 2 or more) units m (m is an integer of 1 or more) connected in parallel. Integer) stages of capacitor banks connected in series, an energy converter connected to an AC power source and capable of controlling rapid charging / discharging of the capacitor banks, and equal charging for applying an equal voltage to each series stage of the capacitor banks An auxiliary device; and voltage detection means for detecting the voltage of each series stage of the capacitor bank. When all the detected values of the voltage detection means are below a predetermined value, the energy conversion device charges the capacitor bank. Then, when at least one of the detection values of the voltage detection means exceeds a predetermined voltage value, the controller It is characterized in that so as to charge the Nsabanku.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the energy storage apparatus using the electric double layer capacitor which can perform equal charge safely with a comparatively simple circuit structure.

  Embodiments of the present invention will be described below with reference to the drawings.

  Hereinafter, an energy storage device using an electric double layer capacitor according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of an energy storage device using an electric double layer capacitor of the present invention.

  The capacitor bank 1 is composed of m (m is an integer of 1 or more) parallel and n (n is an integer of 2 or more) stage series electric double layer capacitors 111, 112,... 11m,. Yes. Both ends of the capacitor bank 1 are connected to the DC terminal of the energy conversion device 2, and the AC terminal of the energy conversion device 2 is connected to the AC system. When the capacitor bank 1 is charged, the AC power of the AC system is converted to DC by the energy conversion device 2 and charged with a constant current. When the capacitor bank 1 is discharged, the DC power stored in the capacitor bank 1 is AC converted by the energy conversion device 2. It is converted into an AC system and regenerated.

  Each series stage of the capacitor bank 1 is connected to the DC output of the equal charge compensator 3 for each series stage. The input of the equal charge compensator 3 is connected to an AC system, and AC power from the AC input is converted to each DC output.

  The operation of the energy conversion device 2 and the operation of the equal charge compensation device 3 are automatically switched by the output of the charge switching control device 4. In order to perform this switching operation, the charge overvoltage detection circuit 5 detects the voltage of each series stage of the capacitor bank 1, and the charge overvoltage detection circuit 5 is charged when the voltage of any series stage exceeds a predetermined voltage. A switching command is output to the switching control device 4. Based on this switching command, the charging switching control device 4 switches from the collective charging operation by the energy conversion device 2 to the individual uniform charging operation by the uniform charging compensator 3.

  The charging operation in the above will be described with reference to an operation flowchart at the time of charging shown in FIG.

  First, charging of the capacitor bank 6 is started by a command from the entire system (ST1). Then, the charge switching control device 4 selects the energy conversion device 2, and the constant current charging operation by the energy conversion device 2 is performed (ST2). In this state, the charge overvoltage detection circuit 5 monitors the voltage of each series stage of the capacitor bank 1, and when the voltage of any series stage exceeds a predetermined voltage, the charge overvoltage detection circuit 5 detects the charge switching control device. A switching command is output to 4 (ST3).

  Based on this switching command, the charge switching control device 4 is switched from the collective charging operation by the energy conversion device 2 to the individual equal charging operation by the equal charge compensator 3 to perform individual equal charging (ST5). When the added value of the detection voltages of the charge overvoltage detection circuit 5 reaches a predetermined rated voltage, full charge is completed (ST6).

  In the above description, when the uneven charging voltage variation of the capacitors is ± 5%, the predetermined voltage of the charging overvoltage detection circuit 5 is set to 90% of the rated voltage of the electric double layer capacitor. In this way, charging overvoltage can be prevented and the entire charging time can be minimized. It is also possible to minimize the equipment capacity of the equal charge compensator 3.

  FIG. 3 is a circuit configuration diagram showing an example of a uniform charge compensator. An AC input from the AC system is converted into a high-frequency AC by a high-speed switching power supply 31 and supplied to the primary winding of the high-frequency transformer 32. The high-frequency transformer 32 has n or more insulated secondary windings which are the number of series stages of the capacitor bank 1, and each secondary winding output is rectified by a diode 33 to each of the capacitor banks 1 in series. Supply to stage electric double layer capacitor.

  In this configuration, the output voltage of the secondary winding of the high-frequency transformer 32 is an output voltage that takes into account the forward voltage drop characteristics of the diode 33 and the rated charging voltage of the electric double layer capacitor. When the charging current is large at the start of uniform charging by the uniform charging compensator 3, the forward voltage drop of the diode 33 is large, and each voltage obtained by subtracting the forward voltage drop of the diode 33 from the output voltage of the secondary winding of the high frequency transformer 32. Applied to an electric double layer capacitor. However, when full charge is reached, the charging current becomes almost zero ampere, and therefore the forward voltage drop of the diode 33 becomes almost zero volts, and the rated charging voltage is applied to the capacitor. By such an action, the energy storage efficiency of the energy storage device can be increased.

  FIG. 4 is a circuit configuration diagram showing an example of the charge overvoltage detection circuit 5. The voltage of each series stage of the capacitor bank 1 is compared by the comparators 52a, 52b,..., 52n with the predetermined reference voltages set by the reference voltage setting devices 51a, 51b,. The comparators 52a, 52b,..., 52n each output 1 when the voltage of the series stage is higher than the reference voltage. Since the outputs of the comparators 52a, 52b,..., 52n are supplied to the OR circuit 53, the OR circuit 53 outputs 1 when the voltage of any series stage exceeds a predetermined value.

  In the above description, the case where the capacitor bank is charged in the energy storage device has been described. However, after the charging, the voltage of the capacitor bank may be reduced by the natural discharge of each electric double layer capacitor before shifting to the above-described discharge operation. Conceivable.

  In the above case, when the detection voltage of all the series stages by the charge overvoltage detection circuit 5 becomes equal to or lower than the predetermined voltage, the charge switching control device 4 operates the equal charge compensator 3 to perform equal charge again. You can do it.

  Hereinafter, an energy storage device using an electric double layer capacitor according to Embodiment 2 of the present invention will be described with reference to FIGS.

  FIG. 5 is a circuit configuration diagram showing a voltage detection method different from that of the first embodiment applicable to the charge overvoltage detection circuit 5. The positive electrode of the electric double layer capacitor 1 nm is connected to the REF terminal of the shunt regulator 55 via the resistor 54, and the negative electrode of the electric double layer capacitor 1 nm is connected to the anode terminal of the shunt regulator 55. A control voltage P5 is applied between the anode terminal and the cathode terminal of the shunt regulator 55 via a resistor 56 and a photocoupler 57 connected in series on the cathode side.

  In the above circuit configuration, the shunt regulator 55 is selected so that the reference voltage becomes the REF reference voltage of the shunt regulator 55, and the control voltage P5 is selected to be a voltage exceeding the REF reference voltage. In this way, when the voltage of the electric double layer capacitor 1 nm exceeds the REF reference voltage of the shunt regulator 55, the photocoupler 57 can be operated. The voltage detection characteristics of the shunt regulator are not easily affected by temperature fluctuations and are essentially unaffected by the cathode current. Therefore, the circuit configuration shown in FIG. 5 enables high-accuracy voltage detection. Become.

  In the above, the resistance value of the resistor 56 is selected so that the primary side current and the secondary side detection sensitivity of the photocoupler 57 are appropriate. The resistance value of the resistor 54 is selected so that the current flowing into the REF terminal of the shunt regulator 55 is appropriate.

  FIG. 6 is a circuit configuration diagram of a charge overvoltage detection circuit 5A to which the voltage detection method shown in FIG. 5 is applied. The electric double layer capacitor 1 nm is located at the uppermost stage having the highest potential in the series stage, and the electric double layer capacitor 1 (n−1) m is located one stage below. The illustration of the electric double layer capacitor at a stage where the voltage is lower than that of the electric double layer capacitor 1 (n-1) m is omitted.

  The positive electrode of the electric double layer capacitor 1 nm is connected to the REF terminal of the shunt regulator 55a through the resistor 54a, and the negative electrode of the electric double layer capacitor 1nm is connected to the anode terminal of the shunt regulator 55a. A control voltage P5 is applied between the anode terminal and the cathode terminal of the shunt regulator 55a via a resistor 56a and a photocoupler 57a connected in series on the cathode side. The uppermost configuration is basically the same as the circuit configuration shown in FIG. The circuit configuration below the uppermost stage will be described below.

  The positive electrode of the electric double layer capacitor 1 (n-1) m is connected to the REF terminal of the shunt regulator 55b via the resistor 54b, and the negative electrode of the electric double layer capacitor 1nm is connected to the anode terminal of the shunt regulator 55b. The cathode terminal of the shunt regulator 55b is connected to the positive electrode of the electric double layer capacitor 1nm via a resistor 56b and a photocoupler 57b connected in series.

  Similarly, the positive electrode of the electric double layer capacitor one stage lower than the electric double layer capacitor 1 (n-1) m is connected to the REF terminal of the shunt regulator 55c through the resistor 54c, and the negative electrode not shown is connected to the shunt regulator 55c. Connected to the anode terminal. The cathode terminal of the shunt regulator 55c is connected to the positive electrode of the electric double layer capacitor 1 (n-1) m via a resistor 56c and a photocoupler 57c connected in series.

  The outputs of the photocouplers 57a, 57b, 57c,... Are connected in parallel to form an output point, and a control voltage P5a is applied to the output point via a resistor 58.

  If configured as described above, another control power supply P5 is required for voltage detection for the uppermost electric double layer capacitor 1 nm, but the voltage detection power supply for other electric double layer capacitors is one stage. Since the voltage of the upper electric double layer capacitor is used, a control power supply is not required, and therefore the circuit configuration is simplified.

  If even one of the electric double layer capacitors exceeds the reference voltage, the cathode current flows from the cathode to the anode of the corresponding shunt regulator, the secondary side of the photocoupler becomes conductive, and the potential of the so-called wired OR circuit, which is the output point. Changes from H to L. Since the wired OR circuit is formed by connecting the secondary outputs of the photocouplers in parallel as described above, the output circuit can be simplified.

The block block diagram of the energy storage apparatus using the electric double layer capacitor of this invention. The operation | movement flowchart at the time of charge. The circuit block diagram which shows one example of a uniform charge compensation apparatus. The circuit block diagram which shows one example of a charge overvoltage detection circuit. The circuit block diagram which shows an example of the voltage detection method applicable to a charge overvoltage detection circuit. The circuit block diagram of the charge overvoltage detection circuit in Example 2 of this invention.

Explanation of symbols

1 capacitor bank 111, 11m, 1n1, 1 (n-1) m, 1nm electric double layer capacitor

2 Energy Converter 3 Equal Charge Compensator 31 High Frequency Switching Power Supply 32 High Frequency Transformer 33 Diode

4 Charge switching control device 5 Charge overvoltage detection circuit 51a, 51b, 51c Reference voltage setting device 52a, 52b, 52c Comparator 53 OR circuit 54, 54a, 54b, 54c Resistor 55, 55a, 55b, 55c Shunt regulator 56, 56a, 56b, 56c Resistors 57, 57a, 57b, 57c Photocoupler

Claims (6)

A capacitor bank in which m (m is an integer of 1 or more) unit-connected double-layer capacitors connected in parallel with n (n is an integer of 2 or more) stages connected in series;
An energy conversion device connected to an AC power source and capable of controlling rapid charge / discharge of the capacitor bank;
An equal charge auxiliary device for applying an equal voltage to each series stage of the capacitor bank;
Voltage detecting means for detecting the voltage of each series stage of the capacitor bank;
When all the detection values of the voltage detection means are below a predetermined value, the capacitor bank is charged by the energy conversion device,
Energy storage using an electric double-layer capacitor, wherein the capacitor bank is charged by the equal charge auxiliary device when at least one of detection values of the voltage detection means exceeds a predetermined voltage value apparatus.   2. The capacitor bank according to claim 1, wherein the capacitor bank is charged by the equal charge assisting device when the capacitor bank is naturally discharged and all the detected values of the voltage detecting means are equal to or less than a predetermined value. Energy storage device using an electric double layer capacitor. The equal charge assist device is:
A high-frequency switching power supply that converts AC or DC input to high-frequency AC output;
The output of this high frequency switching power supply is used as the primary winding input.
A high-frequency transformer having at least n secondary windings;
The energy storage device using an electric double layer capacitor according to claim 1 or 2, comprising rectifying means for rectifying the AC output of each secondary winding. The voltage detection means includes
A shunt regulator is provided corresponding to the series stage of each of the capacitors,
Applying a voltage exceeding the predetermined voltage value by voltage applying means between the anode and cathode of each shunt regulator,
Applying the capacitor voltage of each series stage between the anode terminal and the REF terminal of each corresponding shunt regulator;
The energy storage device using an electric double layer capacitor according to any one of claims 1 to 3, wherein a change in cathode current of the shunt regulator is detected directly or indirectly. The voltage applying means includes
In the stage having the highest voltage among the series stages, a voltage is applied by a control power source provided separately,
In the other stage, a voltage is applied between the negative electrode of the capacitor in the stage for detecting the voltage and the positive electrode of the capacitor in a stage whose voltage is one higher than that in the stage for detecting the voltage. Item 5. An energy storage device using the electric double layer capacitor according to Item 4. The voltage detection means includes
The cathode current of each shunt regulator is received by a photocoupler,
5. The energy storage device using an electric double layer capacitor according to claim 4, wherein the secondary outputs of the respective photocouplers are connected in parallel to form a wired OR circuit.

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