JP5416836B2 - Power storage device using capacitor - Google Patents

Description

  The present invention provides an initial drive for a control circuit for a power storage device at the start of power storage of the power storage device using a capacitor such as an electric double-layer capacitor (hereinafter referred to as EDLC). It is related with the power supply device which supplies the power supply of.

In a power storage device using a capacitor such as an EDLC, the rated voltage of the capacitor alone is as low as about 2.3 to 4.0 [V]. Therefore, in order to obtain a required output voltage, a plurality of capacitors are connected in series. Often used. In many cases, they are connected in parallel to increase the storage capacity. That is, in a power storage device using a capacitor, a plurality of capacitors are often used in series-parallel connection.
However, since a capacitor has a large capacitance error, when a plurality of capacitors are connected in series, the capacitor having a small capacitance is fully charged at the time of charging, and if the charging is continued, the capacitance is reduced. The voltage across the terminals of small capacitors exceeds the rated voltage, causing deterioration and destruction.

Therefore, in a power storage device using a capacitor, during the charging process, it is possible to suppress variations in the voltage between terminals of each capacitor due to capacitance error of the capacitors constituting the power storage unit, and to prevent overcharging of each capacitor. It is necessary to perform control to do this.
Therefore, in general, a power storage device using capacitors suppresses variations in the voltage between the terminals of the power storage unit composed of a plurality of capacitors connected in series and in parallel, and overcharges of each capacitor. It is comprised from the control part for preventing.

In addition to the functions described above, various functions have been proposed for various purposes such as input current control to the power storage unit and output current control to the load. However, since any control unit is configured by an analog circuit, a logic circuit, or a control element such as a microprocessor, PLD, or FPGA, a power source for the control unit itself is required.

Patent 3341951 (Japanese Patent Laid-Open No. 11-215695) Series-parallel switching power supply Patent 3487780 (JP 2000-253572) Connection switching control capacitor power supply Patent 4789924 Power storage device using capacitor and control method thereof PCT / JP2005 / 019208 Power storage device using capacitor and control method thereof WO2007046138 Charge Storing Device Using Capacitor and Its Control Method Patent No. 3854592 (Japanese Patent Laid-Open No. 2005-80469) Battery Charger Device Patent No. 3746633 (Japanese Patent Laid-Open No. 2002-10510) Electrical energy storage device, cell energy amount adjusting device, and cell energy amount adjusting method JP2007-252078 Equal storage / discharge circuit Patent application title: Capacitor power storage device and charge / discharge method thereof Patent application title: Equalizing circuit for assembled battery JP-A-2006-109620 Voltage control device for capacitor and capacitor module provided with the same

  However, there is not much suggestion about the power supply of the circuit of such a control unit. Although there is a method of using a primary battery or a secondary battery as a power source for the control unit, the power storage device using a capacitor is characterized in that the cycle life of the capacitor is extremely longer than that of the battery in the first place, and requires little maintenance. Use of a battery having a life much shorter than that of a capacitor as the power source of the control circuit impairs the characteristics of the power storage device using the capacitor.

There is also a power storage device that presupposes that only the electric power stored in the capacitor of the power storage unit is used as the power source of the control circuit. However, in this method, when the capacitor of the power storage unit is in a fully discharged state, there is no control. In this state, charging of the capacitor of the power storage unit is started, electric charges are gradually accumulated in the capacitor, and the control circuit enters an operating state after the output voltage of the power storage unit reaches a value that can be used as the power source of the control circuit.
That is, the control circuit cannot be operated for a while immediately after the start of charging of the capacitor of the power storage unit, and if the power storage unit is configured by a capacitor with a large capacitance, the output of the power storage unit Since a relatively long time is required until the voltage reaches a value that can be used as the power source of the control circuit, the uncontrolled state is continued for a long time.

However, the control circuit is preferably in an operating state from the start of charging the power storage unit. The reason is described below.
Until now, regarding power storage devices using capacitors, it is possible to suppress variations in terminal voltages caused by capacitance errors and self-discharge of the capacitors constituting the power storage unit, and to align the voltages between terminals of all capacitors (below, Various methods have been proposed to prevent overcharging of the capacitor.

  For example, a method using a voltage equalization circuit (also called a parallel monitor) using resistors as in Patent Documents 1 to 3, or a voltage equalization using a transformer or coil as in Patent Documents 4 to 7. There is a circuit, a voltage equalizing circuit using a capacitor as in Patent Document 8 or Patent Document 9, and the like. The control unit controls these pressure equalizing circuits.

However, regardless of which voltage equalization circuit is used, charging the capacitor of the power storage unit in a fully discharged state is started by using the method of using the power stored in the capacitor of the power storage unit as the power source of the control unit. Until the electric charge is gradually accumulated and the voltage reaches a value that can be used as the power source of the control circuit, the non-control state is continued, and the voltage equalizing circuit does not operate.
When the non-control state continues for a long time, the variation in the voltage between the terminals of the capacitor of the power storage unit increases. Therefore, even if the voltage equalization circuit is operated when the voltage of the capacitor of the power storage unit has reached a value that can be used as the power supply of the control circuit and the control circuit becomes operable, the voltage equalization is not in time or expanded. In order to suppress the variation in the voltage between the terminals between the capacitors, a large amount of energy stored in the power storage unit must be consumed.
When a control method called serial-parallel switching is used in the power storage unit as in Patent Documents 1 to 3, charging is generally started by switching all capacitors of the power storage unit to series connection. However, when the capacitor of the power storage unit is in a completely discharged state and the control unit is not operating, even the switching control cannot be performed, and the power storage unit itself cannot be charged.
For the above reasons, it is possible to suppress variations in the inter-terminal voltage between capacitors from the start of charging by operating the control unit simultaneously with the start of charging of the capacitor of the power storage unit and performing a pressure equalizing operation. preferable. By doing so, the power energy input to the capacitor of the power storage unit can be stored without waste, and the charging time can be shortened.

Therefore, the present invention proposes an initial driving power source for operating a control circuit from the time when charging of the capacitor of the power storage unit is started in a power storage device using a capacitor such as an EDLC for the power storage unit. The power source for initial drive of this control circuit also requires a power storage element, and a capacitor such as an EDLC having a long cycle life is used as the power storage element.
This initial drive power supply is a circuit that supplies drive power to the control circuit until at least the output voltage of the power storage unit reaches the drive voltage of the control circuit, and the output voltage of the power storage unit is the drive voltage of the control circuit. It is possible to adopt a circuit configuration that supplies drive power to the control circuit even after reaching the control circuit.After the output voltage of the power storage unit reaches the drive voltage of the control circuit, the drive power of the control circuit is supplied from the power storage unit. A circuit configuration to be supplied may be employed.

In the power storage device using the capacitor according to claim 1 of the present invention,
In a power storage device including a main power storage unit using a capacitor, a control circuit for controlling power storage from a DC power source to the main power storage unit, and discharging from the main power storage unit to a load,
In a power storage device including a sub power storage unit serving as a power source for the control circuit in an initial state in which power supply from the DC power source is started,
A capacitor is used for the sub power storage unit,
The main power storage unit is connected to the DC power source via a make contact switch for charging that performs a make contact operation,
A detection circuit for detecting a voltage between terminals of the sub power storage unit;
The control circuit starts operation by supplying power from the sub power storage unit after the inter-terminal voltage of the sub power storage unit detected by the detection circuit is equal to or higher than the operation voltage of the control circuit, The charging make contact switch is closed to start power storage from the DC power source to the main power storage unit, and to start predetermined power storage control,
The sub power storage unit is connected to the DC power source via a break contact switch that performs a break contact operation.
The control circuit is configured to open the break contact switch after the inter-terminal voltage of the sub power storage unit detected by the detection circuit becomes equal to or higher than a charging completion voltage.
In claim 2,
The load is connected to the main power storage unit via a discharge make contact switch,
The control circuit is configured to close the discharge make contact switch to be in a dischargeable state after the output voltage of the main power storage unit becomes equal to or higher than a predetermined dischargeable voltage.
In claim 3,
The power source of the control circuit is connected to the output voltage of voltage conversion means for converting the voltage between the terminals of the sub power storage unit into a predetermined operating voltage,
The voltage conversion unit is configured to supply the output voltage as a power source of the control circuit after the voltage between the terminals of the sub power storage unit becomes equal to or higher than the predetermined convertible voltage.
In claim 4,
The voltage conversion means is voltage conversion means for converting the output voltage of the sub power storage unit into an operating voltage of the control circuit.
In claim 5,
Step-down voltage conversion means for stepping down the output voltage of the main power storage unit and charging the sub power storage unit is provided.
In claim 6,
The break contact switch is
A thyristor connected in series between the DC power supply and the sub power storage unit;
A depletion-type nMOSFET that is connected in parallel to the source and gate of the thyristor, is turned on when DC power supply starts, turns on the thyristor, and is turned off by a break control signal from a control circuit;
It includes an enhancement type nMOSFET that is connected in parallel to the source and drain of the thyristor and turned off after being turned on by a break control signal from a control circuit to turn off the thyristor.
In claim 7,
The break contact switch is
A thyristor connected in series between the DC power supply and the sub power storage unit;
An enhancement-type nMOSFET that is connected in parallel to the source and gate of the thyristor, is turned on by supplying a DC power supply to turn on the thyristor, and is turned off by a break control signal from a control circuit;
It includes an enhancement type nMOSFET that is connected in parallel to the source and drain of the thyristor and turned off after being turned on by a break control signal from a control circuit to turn off the thyristor.

According to the power storage device using the capacitor according to claim 1 of the present invention,
After the voltage between the terminals of the sub power storage unit detected by the detection circuit becomes equal to or higher than the operating voltage of the control circuit, power is supplied from the sub power storage unit to the control circuit, and the control circuit starts operation. Reliable operation is possible.
Then, after the control circuit starts a reliable operation, the charging make contact switch is closed to start power storage from the DC power source to the main power storage unit and to start predetermined power storage control by the control circuit Therefore, proper power storage to the main power storage unit can be performed.
further,
Since the sub power storage unit is connected to the DC power supply via a break contact switch that performs a break contact operation, when the power supply is started from the DC power supply, the break contact switch is in an on state, and the DC power supply Charging to the sub power storage unit is surely started.
Then, after the voltage between the terminals of the sub power storage unit detected by the detection circuit becomes equal to or higher than the charging completion voltage, the break contact switch is opened to finish charging the sub power storage unit. Can be charged properly.
In claim 2,
After the output voltage of the main power storage unit becomes equal to or higher than a predetermined dischargeable voltage, the discharge make contact switch is closed to enable discharge, so that reliable discharge is possible.
In claim 3,
Since the output voltage from the sub power storage unit is supplied as the power source of the control circuit after the voltage between the terminals of the sub power storage unit becomes equal to or higher than the predetermined convertible voltage in the voltage conversion means, the control circuit operates reliably. To do.
In claim 4,
Since the voltage conversion means converts the output voltage of the sub power storage unit into the operating voltage of the control circuit, the control circuit can be driven properly even when the rated voltage of the sub power storage unit is different from the operating voltage of the control circuit. .
In claim 5,
Since it includes step-down voltage conversion means that steps down the discharge voltage of the main power storage unit and charges the sub power storage unit, proper charging is possible even when the rated voltage of the main power storage unit is higher than the rated voltage of the sub power storage unit. The voltage can be supplied to the sub power storage unit.
In claim 6,
The break contact switch is
A thyristor connected in series between the DC power supply and the sub power storage unit;
A depletion-type nMOSFET that is connected in parallel to the source and gate of the thyristor, is turned on when DC power supply starts, turns on the thyristor, and is turned off by a break control signal from a control circuit;
An enhancement-type nMOSFET that is connected in parallel to the source and drain of the thyristor, turned on by a break control signal from a control circuit to turn off the thyristor, and then turned off.
At the start of supplying DC power, the depletion type nMOSFET is in an ON state, the thyristor is turned on, and charging of the sub power storage unit is started.
The depletion-type nMOSFET is turned off by a break control signal from the control circuit, and the enhancement-type nMOSFET is turned on to turn off the thyristor by setting the source current of the thyristor below the holding current, and then the enhancement-type nMOSFET is turned off and the secondary power storage To finish charging the
By outputting a break control signal from the control circuit when the sub power storage unit is fully charged, the sub power storage unit can be appropriately charged.
In claim 7,
The break contact switch is
A thyristor connected in series between the DC power supply and the sub power storage unit;
A depletion-type nMOSFET that is connected in parallel to the source and gate of the thyristor, is turned on when DC power supply starts, turns on the thyristor, and is turned off by a break control signal from a control circuit;
An enhancement-type nMOSFET that is connected in parallel to the source and drain of the thyristor, turned on by a break control signal from a control circuit to turn off the thyristor, and then turned off.
At the start of supplying DC power, the depletion type nMOSFET is in an ON state, the thyristor is turned on, and charging of the sub power storage unit is started.
The depletion-type nMOSFET is turned off by a break control signal from the control circuit, and the enhancement-type nMOSFET is turned on to turn off the thyristor by setting the source current of the thyristor below the holding current, and then the enhancement-type nMOSFET is turned off and the secondary power storage To finish charging the
By outputting a break control signal from the control circuit when the sub power storage unit is fully charged, the sub power storage unit can be appropriately charged.
In claim 8,
The break contact switch is
A thyristor connected in series between the DC power supply and the sub power storage unit;
An enhancement type nMOSFET that is connected in parallel to the source and gate of the thyristor, is turned on by supplying a DC power supply to turn on the thyristor, and is turned off by a break control signal from a control circuit (reference numeral “45” in FIG. 4). Attached)
An enhancement type nMOSFET connected in parallel to the source and drain of the thyristor, turned on by a break control signal from a control circuit to turn off the thyristor, and then turned off (indicated by reference numeral “46” in FIG. 4). And)
At the start of supplying DC power (indicated by reference numeral “45” in FIG. 4), the enhancement type nMOSFET is turned on to turn on the thyristor and start charging the sub power storage unit,
The enhancement type nMOSFET is turned off (labeled “45” in FIG. 4) by a break control signal (“third” in FIG. 4) from the control circuit, and then the “fourth” in FIG. 4) break. After the enhancement type nMOSFET is turned on by the control signal (indicated by reference numeral “46” in FIG. 4) to turn off the source current of the thyristor below the holding current (“fourth” in FIG. 4), the break control By stopping the signal, the enhancement type nMOSFET (labeled “46” in FIG. 4) is turned off and charging of the sub power storage unit is completed.
By stopping the break control signal ("fourth" in FIG. 4) output from the control circuit when the sub power storage unit is fully charged, the sub power storage unit can be appropriately charged.

It is a block diagram of Example 1 of a power storage device using a capacitor. It is a block diagram of Example 2 of the electrical storage apparatus using a capacitor. It is a block diagram of Example 3 of a power storage device using a capacitor. It is a block diagram of Example 4 of the electrical storage apparatus using a capacitor. It is explanatory drawing of a main electrical storage part.

  Hereinafter, a power storage device using a capacitor according to the present invention will be described with reference to the drawings showing examples.

  FIG. 1 shows a configuration example of a power storage system using an EDLC as a power storage element for an initial driving power source of a control circuit of a power storage device using a capacitor.

<Description of each element>
In FIG.
DC is a direct current power source and is preferably a current source, but may be a voltage source. As the DC power source DC, for example, a small-scale power generation device using natural energy such as a solar panel or a wind power generation device is often used, but other power supply sources can also be used. In some cases, DC is used.
SW1 is a break contact switch, and is composed of an open / close switch configured to close and conduct when no break control signal is input, and to open and shut off when the break control signal is input. .
SW2 is a make contact switch for charging the main power storage unit. When no charge control signal is input, the contact opens and shuts off, and when the charge control signal is input, the contact closes to store the main power storage unit. It is comprised with the opening-and-closing switch comprised so that it may conduct.
SW3 is a make-up contact switch for discharge, and is an open / close switch configured to open and shut off when no discharge control signal is input, and to close when the discharge control signal is input and to conduct for discharge. It consists of switches.

  Reference numeral 1 denotes a control circuit that outputs the break control signal, the charge control signal, the discharge control signal, and a power storage unit control signal described later based on a predetermined control program, and detects a voltage between terminals described later. A signal and a power storage unit state signal are input.

Cst is an EDLC as an initial driving power source of the control circuit 1 and corresponds to the sub power storage unit described in the claims. Hereinafter, it is simply referred to as “start capacitor Cst”.
An inter-terminal voltage detection circuit 2 detects the inter-terminal voltage of the start capacitor Cst and outputs an inter-terminal voltage detection signal to the control circuit 1.
Reference numeral 3 denotes a DC-DC converter as voltage conversion means, which converts the voltage stored in the start capacitor Cst into a DC voltage required by the control circuit 1 and supplies it as an operating power source for the control circuit 1. .

Cm is a power storage unit and corresponds to the main power storage unit described in the claims. In this embodiment, a predetermined number of EDLCs are connected in series, and the stored power is supplied to the discharge make contact SW3. It is comprised so that it may supply to load R via.
D1, D2, D3, D4, D5, and D6 are backflow prevention diodes, respectively.

<Description of the interconnection state of each element>
The anode terminal of the backflow prevention diode D1 is connected to the output terminal DC + on the + side of the DC power source DC. The cathode terminal of the backflow prevention diode D1 is connected to one end of the break contact switch SW1 and the make contact switch SW2. One end is connected together.
The other end of the break contact switch SW1 is connected to the anode terminal of the backflow prevention diode D2. The cathode terminal of the backflow prevention diode D2 is connected to one end Cst + of the start capacitor Cst. The negative output terminal DC− of the DC power source DC is connected to a ground side wiring (indicated by a ground symbol), and the other end Cst− of the start capacitor Cst is also connected to the ground side wiring. Yes.

An anode terminal of a backflow prevention diode D5 is connected to the other end of the charging make contact switch SW2, and a cathode terminal of the backflow prevention diode D5 is connected to a positive terminal Cm + of the power storage unit Cm and the discharging make. One end of the contact SW3 is connected together. The negative terminal Cm− of the power storage unit Cm is also connected to the ground wiring.
The anode terminal of the backflow prevention diode D6 is connected to the other end of the discharge make contact SW3, and the cathode terminal of the backflow prevention diode D6 is connected to the + side discharge output terminal T +. One end of the load R can be connected to the discharge output terminal T +. Note that the other end of the load R can be connected to the negative discharge output terminal T-.

The break control signal output terminal 11 of the control circuit 1 is connected to the control signal input terminal B1 of the break contact switch SW1, and the charge control signal output terminal 12 of the control circuit 1 controls the make contact switch SW2 for charging. Connected to the signal input terminal M1, the discharge control signal output terminal 13 of the control circuit 1 is connected to the control signal input terminal M2 of the discharge make contact switch SW3.
The detection terminals 21 and 22 of the inter-terminal voltage detection circuit 2 are connected to both poles of the start capacitor Cst, and the detection signal output terminal 23 is connected to the detection voltage input terminal 14 of the control circuit 1 to detect the inter-terminal voltage detection signal. Is output to the control circuit 1.

An input terminal 31 of the DC-DC converter 3 is connected to a positive terminal of the start capacitor Cst via a backflow prevention diode D3, and an input terminal 32 is connected to a negative terminal of the start capacitor Cst. .
The input terminal 31 is also connected to a positive terminal of the power storage unit Cm via a backflow prevention diode D4.
Any of the backflow prevention diodes D3 and D4 is connected with the direction toward the input terminal 31 as the forward direction.
The output terminal 33 of the DC-DC converter 3 is connected to the power supply terminal 15 of the control circuit 1 and is configured to supply the control circuit 1 with the DC power converted by the DC-DC converter 3.

  The control signal input terminal Cm1 of the power storage unit Cm is connected to the control signal output terminal 16 of the control circuit 1 through a plurality of signal lines, and the power storage unit control signal is transmitted from the control circuit 1 to the power storage unit Cm. Has been. The state signal output terminal Cm2 of the power storage unit Cm is connected to the state signal input terminal 17 of the control circuit 1 through a plurality of signal lines, and is configured to transmit the power storage unit state signal from the power storage unit Cm to the control circuit. ing.

<Description of operation>
The figure shows that the rated voltage of Cst (hereinafter referred to as start capacitor), which is an EDLC as the power source for initial drive of the control circuit, and the rated output voltage of the power storage unit Cm are within the input voltage range of the DC-DC converter. The configuration when it fits is shown. The DC power source DC in the figure is preferably a current source, but may be a voltage source.
1 has a configuration in which a plurality of capacitors are connected in series. However, the present invention is not limited to this, and the power storage unit Cm includes a plurality of capacitors that need some control in series and parallel. Any connected configuration may be used. Hereinafter, an operation of power storage device 10 shown in FIG. 1 will be described.
In FIG. 1, the break contact switch SW1 is a switch that operates as a normally-closed contact, and the make-up contact switch SW2 for charging and the make-contact switch SW3 for discharge operate as normally-open contacts. It is a switch to do.

<Description of initial charging operation>
Before starting to charge the power storage unit Cm, first, a capacitor Cst (start capacitor) as an initial driving power source of the control circuit 1 is charged. That is, in the initial state where no power is supplied to the control circuit 1, the switches SW2 and SW3 are open because they are make contacts, and the switch 1 is closed because SW1 is a break contact. It flows into only Cst and does not flow into the capacitor of the power storage unit Cm.
As shown in FIG. 1, a DC-DC converter 3 is connected to both terminals of the start capacitor Cst via a backflow prevention diode D3, and the output voltage of the start capacitor Cst is normal for the control circuit 1. It is set so as to be a constant driving voltage necessary for driving. When the start capacitor Cst is constituted by one EDLC, the rated voltage is generally less than the drive voltage of the control circuit 1 in many cases. In such a case, a step-up DC-DC converter may be used as the DC-DC converter 3.

When the current from the DC power source DC flows into the start capacitor Cst, the electric charge is accumulated, and the voltage between the terminals rises to the operable voltage of the DC-DC converter 3, the DC-DC converter 3 is activated to control the circuit. Since electric power is supplied to 1, the control circuit 1 is in a state where the power storage unit Cm can be controlled. However, at this time, the control circuit 1 does not yet start the control operation of the power storage unit Cm.
When the current from the DC power source DC continues to flow into the start capacitor Cst and eventually the start capacitor Cst becomes fully charged, the full charge is detected by the voltage detection circuit 2 between the terminals of the start capacitor Cst, and the full charge is detected. A signal is input as a voltage detection signal between terminals of the start capacitor Cst from the detection signal output terminal 23 to the control circuit 1 which is already operable. When the full charge detection signal of the start capacitor Cst is input to the control circuit 1, the control circuit 1 starts a series of control operations described later.
In the case where the DC-DC converter 3 is of a type having an input voltage monitoring function, full charge of the start capacitor Cst is detected by the input voltage monitoring function, and the full charge detection signal is indicated by a broken line in the figure. Thus, the configuration may be such that the input is made to the control circuit 1 already in an operable state.
Further, instead of detecting the full charge of the start capacitor Cst by the inter-terminal voltage detection circuit 2 as described above, a predetermined voltage equal to or lower than the full charge voltage is detected, and the predetermined voltage is used as the inter-terminal voltage detection signal. A detection signal may be output.

When the full charge detection signal of the start capacitor Cst is input to the control circuit 1, the control circuit 1 starts a series of control operations described later.
However, the power consumed by the DC-DC converter 3 and the control circuit 1 is smaller than the inflow power to the start capacitor Cst, and the capacitance of the start capacitor Cst is at least from the start of charging the power storage unit Cm. Assume that the capacitance is set such that the electric power that can guarantee the operation of the control circuit 1 can be accumulated until the output voltage Vt of the power storage unit Cm becomes larger than the voltage between the terminals of the start capacitor Cst. Therefore, as long as power is supplied from the direct current power source DC, the control circuit 1 does not stop its operation once it is operable.
When the DC power source DC is a solar battery or the like, the electrostatic capacity of the start capacitor Cst is such that the power that can guarantee the operation of the control circuit 1 can be stored at night or during the non-sunshine guarantee period. Assume that the capacitance is set.

  When the full charge detection signal of the start capacitor Cst is input to the control circuit 1, the control circuit 1 first sends a signal for turning off the break contact switch Sw1, and stops charging the start capacitor Cst. This signal for turning off the break contact switch SW1 is a time until the charge of the start capacitor Cst decreases due to power consumption or self-discharge by the control circuit 1, and the start capacitor Cst needs to be charged again from the DC power source DC. In the meantime, transmission from the control circuit 1 is continued.

  The control circuit 1 sends a break control signal for turning off the break contact switch SW1, stops charging the start capacitor Cst, and then sends a charge control signal for turning on the make contact switch SW2 for charging. The current from DC is guided to the capacitor of the power storage unit Cm, and control of the power storage unit Cm is started.

<Description of charging operation to power storage unit>
The power storage unit control signal sent from the control circuit 1 to the power storage unit Cm differs depending on the configuration of the power storage unit Cm and the control method of the power storage unit Cm, but basically the control circuit 1 indicates the state of the power storage unit Cm. A state signal is taken in, a power storage unit control signal corresponding to these signals is determined, and sent to the power storage unit Cm. (Generally, a power storage unit control signal is sent from the control circuit 1 to the power storage unit Cm via a plurality of signal lines.)
When a charging current flows from the DC power source DC into the capacitor of the power storage unit Cm and electric charges are accumulated, the output voltage Vt of the power storage unit Cm increases. Since the outputs of the start capacitor Cst and the power storage unit Cm are connected to the input terminal 31 of the DC-DC converter 3 via the backflow prevention diodes D3 and D4, respectively, charges are accumulated in the capacitor of the power storage unit Cm, and eventually When the output voltage Vt of the power storage unit Cm becomes larger than the voltage between the terminals of the start capacitor Cst, the two backflow prevention diodes D3 and D4 act on the DC-DC converter 3 not from the start capacitor Cst but from the power storage unit Cm. Electric power is supplied.
Thereafter, power is supplied from the power storage unit Cm to the control circuit 1 via the DC-DC converter 3 until the output voltage Vt of the power storage unit Cm becomes equal to or lower than the voltage across the terminals of the start capacitor Cst due to discharge to the load or the like. .

<Completion of charging to power storage unit>
When the power storage unit Cm is controlled by the power storage unit control signal from the control circuit 1 and the power storage to the power storage unit Cm proceeds and the power storage unit Cm is in a fully charged state, a full charge detection circuit in the power storage unit Cm (in the drawing) Is not described), the full charge detection signal of the power storage unit Cm is sent to the control circuit 1 as a power storage unit state signal. Receiving the power storage unit state signal, the control circuit 1 sends out a charge control signal for turning off the charging make contact switch SW2, and stops charging the power storage unit Cm. Subsequently, the control circuit sends a discharge control signal for turning on the discharge make contact switch SW3, and starts discharging to the load R.

Even when the power storage unit Cm does not reach the fully charged state, when it is determined by the power storage unit state signal sent from the power storage unit Cm to the control circuit 1 that sufficient power is stored in the power storage unit Cm. Alternatively, the discharging make contact switch SW3 may be turned on to start discharging.
In addition, the charging make contact switch SW2, the discharging make contact SW3, and the backflow prevention diode are incorporated in the power storage unit Cm, and the power storage unit Cm can be charged and discharged simultaneously. In some cases. In such a case, signals necessary for controlling the power storage unit Cm, such as ON / OFF signals of the charging make contact switch SW2 and the discharging make contact SW3 incorporated in the power storage unit Cm, are transmitted from the control circuit 1. It is assumed that it is included in the power storage unit control signal sent to the power storage unit Cm.

<Recharging the start capacitor>
In addition, while the control circuit 1 is in operation by supplying power from the power storage unit Cm, the voltage between the terminals of the start capacitor Cst falls below a set voltage within the operable voltage range of the DC-DC converter 3 due to self-discharge or the like. When the voltage drops, the voltage detection circuit 2 between the terminals of the start capacitor Cst detects this and inputs a low voltage detection signal of the start capacitor Cst to the control circuit 1.
When the low voltage detection signal of the start capacitor Cst is input to the control circuit 1 as the voltage detection signal between the terminals of the start capacitor Cst, the control circuit 1 stops the break control signal for turning off the break contact switch SW1. Then, the break contact switch SW1 is turned ON, and the current from the DC power source DC is caused to flow into the start capacitor Cst to charge the start capacitor Cst. The operation of the control circuit 1 after the start capacitor Cst is fully charged is the same as described above.
By doing so, the voltage between the terminals of the start capacitor Cst is always set to be equal to or higher than a set voltage within the operable voltage range of the DC-DC converter 3.

The control circuit 1 stops the break control signal for turning off the break contact switch SW1 at regular intervals, and turns on the break contact switch SW1 to start the current from the DC power source DC into the start capacitor Cst. The capacitor Cst may be charged so that the voltage between the terminals of the start capacitor Cst is always equal to or higher than a set voltage within the operable voltage range of the DC-DC converter 3.

FIG. 1 shows a configuration example in which the rated voltage of the start capacitor Cst and the rated output voltage of the power storage unit Cm are within the input voltage range of the DC-DC converter 3. However, such a condition is not always satisfied, and the rated output voltage of the power storage unit Cm is often higher than the rated voltage of the start capacitor Cst.
FIG. 2 shows a configuration in the case where the rated output voltage of the power storage unit Cm is larger than the rated voltage of the start capacitor Cst and does not fall within the input voltage range of the DC-DC converter 3A as voltage conversion means. However, in FIG. 2, the allowable input voltage range of the step-down DC-DC converter 3B as the step-down voltage converting means is higher than the rated voltage of the start capacitor Cst, and the output voltage is the rated voltage of the start capacitor Cst. It is assumed that it is set and is set within the input allowable voltage range of the DC-DC converter 3A.
Hereinafter, the operation when the power storage device 10A is configured as shown in FIG. 2 will be described.

The process starting from the charging of the start capacitor Cst, the charging of the power storage unit Cm is started, and the output voltage Vt of the power storage unit Cm becomes larger than the voltage across the terminals of the start capacitor Cst is the same as in the case of FIG. Therefore, explanation is omitted.
In FIG. 2, when charge is accumulated in the power storage unit Cm and the output voltage Vt of the power storage unit Cm becomes larger than the voltage across the terminals of the start capacitor Cst, the output voltage Vt of the power storage unit Cm is reduced to the step-down DC-DC converter 3B. Thus, the voltage is stepped down to the rated voltage of the start capacitor Cst and output.

Since the output terminal 31A of the step-down DC-DC converter 3B is connected in parallel to the start capacitor Cst and the DC-DC converter 3A via the backflow prevention diode D3, the voltage between the terminals of the start capacitor Cst is controlled. When the voltage is reduced due to power consumption by the circuit 1 or self-discharge, the start capacitor Cst is charged by the output of the step-down DC-DC converter 3B, and the output of the step-down DC-DC converter 3B is DC- The voltage is boosted to the drive voltage of the control circuit 1 by the DC converter 3A, and power is supplied to the control circuit 1. The subsequent operation of the control circuit 1 is the same as in FIG.

FIG. 3 shows a more specific circuit configuration example of the second embodiment shown in FIG. As illustrated, the circuit of the power storage device 10B includes a start capacitor Cst, a thyristor Th, a depletion type nMOSFET 41, an enhancement type nMOSFET 42, and the like.
A circuit portion surrounded by a broken line in FIG. 3 and including a thyristor Th, a depletion type nMOSFET 41, an enhancement type nMOSFET 42, and the like corresponds to the break contact switch SW1 in FIG. That is, a depletion type nMOSFET 41 in which a drain current flows even when the gate-source voltage is 0 [V] is used as the break contact switch SW1 in FIG.

However, in general, a depletion type FET can only flow a drain current of about several mA and has a large ON resistance. Therefore, by combining this depletion type nMOSFET and a thyristor Th that is also used in a high power system, the start capacitor Cst can be charged with a relatively large current.
That is, in the state where the power is not supplied to the power source of the control circuit 1B and the control circuit 1B is not operating, the signal from the control circuit 1B is not input to the MOSFET driver 43 of FIG. Therefore, the output of the MOSFET driver 43 is in an OFF state, and the source-drain of the depletion type nMOSFET 41 is in a conductive state (ON state). Accordingly, since a current flows through the base of the transistor Tr, the transistor Tr is also in an ON state, and a current flows into the gate of the thyristor Th.
When a gate current flows in a state where a voltage is applied between the anode and the cathode, the thyristor Th conducts (turns on) between the anode and the cathode, so that the current from the DC power source DC flows to the start capacitor Cst, and the start capacitor Cst. A charge is accumulated in.

The combination of the depletion type nMOSFET 41 and the transistor Tr is used as an element for flowing the gate current of the thyristor Th because the output current of the depletion type nMOSFET 41 alone does not satisfy the turn-on current of the thyristor Th. This is because it is necessary to amplify.
In this way, by supplying a current to the start capacitor Cst via the turned-on thyristor Th, it is possible to charge with a large current that could not be achieved with only the depletion type nMOSFET, and to charge the start capacitor Cst quickly. doing.

When the start capacitor Cst is fully charged, the charging current to the start capacitor Cst must be stopped. For this purpose, the thyristor Th must be stopped. However, the thyristor Th is not cut off (turned off) only by stopping the gate current in a state where the anode and the cathode of the thyristor Th are conductive. In order to cut off (turn off) the thyristor Th, it is necessary to stop the gate current and make the current flowing between the anode and the cathode equal to or less than the holding current.
Therefore, by first turning on the MOSFET driver 43 by the first break control signal from the control circuit 1B that is in the operating state, the depletion type nMOSFET 41 is turned off and the base current of the transistor Tr is stopped. The current flowing through the gate of the thyristor Th is stopped, and then the MOSFET driver 44 is turned on by the second break control signal from the control circuit 1B, whereby the enhancement connected in parallel between the source and drain of the thyristor Th The type nMOSFET 42 is turned on.
By doing so, the current from the DC power source DC is bypassed to the enhancement type nMOSFET 42 having a small ON resistance, so that the current flowing into the source of the thyristor Th falls below the holding current, and the thyristor Th is turned off. Thereafter, by stopping the second break control signal from the control circuit 1B, the MOSFET driver 44 is turned off, and the enhancement type nMOSFET 42 is turned off, thereby stopping the charging of the start capacitor Cst.

The start capacitor Cst is used to drive the control circuit 1B with the electric power accumulated until the output voltage of the power storage unit Cm becomes equal to or higher than the drive voltage of the control circuit 1B. In many cases, the rated voltage of the start capacitor Cst is less than the drive voltage of the control circuit 1B. Therefore, in the above example, the output voltage of the start capacitor Cst is boosted to the drivable voltage of the control circuit 1B by the DC-DC converter 3A.
However, instead of using a DC-DC converter, a plurality of capacitors connected in series may be used as the start capacitor Cst so that the output voltage becomes the driveable voltage of the control circuit 1B.

As described above, the capacitance of the start capacitor Cst is at least from the start of charging the power storage unit Cm until the output voltage Vt of the power storage unit Cm becomes higher than the voltage across the terminals of the start capacitor Cst. Therefore, it is necessary to set the capacitance so that the electric power that can guarantee the operation of the control circuit 1B can be stored.
However, in the circuit of FIG. 3 shown in the third embodiment, the depletion-type nMOSFET 41 must be kept OFF so that the gate signal of the thyristor Th is not input while the power storage unit Cm is continuously charged. . For this purpose, the first break control signal from the control circuit 1B must be continuously output in order to keep the MOSFET driver 43 in the ON state. However, this is generally necessary to keep the MOSFET driver 43 in the ON state. Since the electric current consumed is large and the power consumption by the control circuit 1B is increased, a large start capacitor Cst is required.

FIG. 4 shows a circuit configuration example of a power storage device 10C that can suppress power consumption by the control circuit 1B and can suppress the capacitance of the start capacitor Cst.
D0 to D3, D5, and D6 are backflow prevention diodes. A portion surrounded by a broken line in FIG. 4 corresponds to the break contact switch SW1 in FIG.
Since the major difference between the third embodiment and the fourth embodiment is a portion corresponding to the break contact switch SW1, the operation of this portion will be mainly described below.

That is, when the control circuit 1B is not in operation, no current flows through the base of the transistor Tr in FIG. 4, so that the transistor Tr is in an OFF state, and a reverse current flows from the DC power source DC to the input side of the MOSFET driver 47. Current flows through the prevention diode D0, and the MOSFET driver 47 is turned on.
Accordingly, the gate voltage becomes higher than the source voltage of the enhancement-type nMOSFET 45, the drain-source becomes conductive, the current flows into the gate of the thyristor Th, and the anode-cathode of the thyristor Th becomes conductive (turned on). A current from the DC power source DC flows through the capacitor Cst, and charges are accumulated in the start capacitor Cst.

  Unlike the case of the third embodiment, since the enhancement type nMOSFET 45 is used as an element for flowing the gate current of the thyristor Th in the circuit of FIG. 4, the thyristor Th is turned on without amplifying the current with a transistor or the like. Sufficient current can flow.

When the start capacitor Cst is fully charged, the charging current to the start capacitor Cst must be stopped. For this purpose, the thyristor Th must be stopped. However, the thyristor Th is not cut off (turned off) only by stopping the gate current in a state where the anode and the cathode of the thyristor Th are conductive. In order to cut off (turn off) the thyristor Th, it is necessary to stop the gate current and make the current flowing between the anode and the cathode equal to or less than the holding current.
Therefore, first, by turning on the transistor Tr in FIG. 4 by the third break control signal from the control circuit 1B that is in the operating state, the MOSFET driver 47 is turned off and the enhancement type nMOSFET 45 is turned off. Thus, the current flowing through the gate of the thyristor Th is stopped.

Next, the enhancement type nMOSFET 46 is turned on by turning on the MOSFET driver 48 by the fourth break control signal from the control circuit 1B. By doing so, the current from the DC power source DC is bypassed to the enhancement type nMOSFET 46 having a small ON resistance, so that the current flowing into the source of the thyristor Th falls below the holding current, and the thyristor Th is turned off.
Thereafter, the fourth break control signal from the control circuit 1B is stopped, and the enhancement type nMOSFET 46 is turned off by turning off the MOSFET driver 48. By doing so, charging of the start capacitor Cst is stopped.

As described above, in this embodiment, the output current (third to fourth break control control signals) from the control circuit 1B is necessary because the transistor Tr is turned on, the MOSFET driver 47 is turned off, and the MOSFET When the driver 48 is turned on, the current flowing into the source of the thyristor Th is less than the holding current, and only the time necessary for the thyristor Th to be turned off is required, so that power consumption by the control circuit 1B can be suppressed. Further, the capacitance of the start capacitor Cst can be suppressed smaller than in the case of the third embodiment.

<Capacitance of start capacitor>
Next, the capacitance of the start capacitor Cst will be examined. In the power storage device using the initial drive circuit of the control circuit as described above, when the start capacitor Cst is fully charged, that is, when the rated voltage is reached, charging of the power storage unit Cm is started.
Voltage between terminals of start capacitor Cst <storage unit output voltage Vt (1)
At that time, power to the control circuits 1 and 1B is supplied from the power storage unit Cm.
When the power consumption of the control circuits 1 and 1B is small, after the start capacitor Cst is fully charged, the power storage unit Cm is accumulated in the start capacitor Cst until the condition of the expression (1) is satisfied. The decrease in charge is thought to be small.
Therefore, in order to simplify the calculation, it is assumed below that the start capacitor Cst is fully charged, that is, after reaching the rated voltage, the voltage across the terminals of the start capacitor Cst does not decrease until the expression (1) is satisfied. It is sufficient that the control circuits 1 and 1B can be driven by the charge accumulated in the start capacitor Cst until the output voltage of the power storage unit Cm becomes equal to or higher than the full charge voltage of the start capacitor Cst.

Therefore, the power storage unit Cm has a series configuration of n capacitors,
The rated voltage of each capacitor constituting the power storage unit Cm is Va [V],
The capacitance of each capacitor constituting the power storage unit Cm is C [F],
The output voltage of the power storage unit Cm is Vt [V],
The rated voltage of the start capacitor Cst is Va [V],
The capacitance of the start capacitor Cst is Cs [F],
The lower limit value of the allowable input voltage range of the DC-DC converter 3A is Vss.
[V],
The output current of the DC power supply DC, that is, the charging current is I [A],
The power consumption of the control circuits 1 and 1B is P [W],
Safety factor is S (> 1)
And In the following, in order to simplify the calculation, only the charge flowing into each capacitor of the power storage unit Cm is considered as shown in FIG. 5, and the charge flowing into the start capacitor Cst is ignored.

First, as shown in FIG. 5, all n capacitors constituting the power storage unit Cm are connected in series, and charging is started with a charging current I [A].
Full charge voltage of start capacitor = Output voltage Vt of power storage unit Cm (2)
The time t [sec] required to become is obtained.
Assuming that the voltage across the terminals of the start capacitor Cst in the fully charged state is equal to the rated voltage Va [V], if there is no capacitance error in each capacitor of the power storage unit Cm,
Terminal voltage Vc [V] = Va / n [V] of each capacitor of power storage unit Cm
It becomes. Therefore, the time t [sec] required until the expression (2) is established is C (Va / n) = It,
t = CVa / (nI) [seconds] (3)
It becomes.

Here, after the start capacitor Cst is fully charged, after the control circuits 1 and 1B are driven and charging of the power storage unit Cm is started, the drive power of the control circuits 1 and 1B is supplied to the start capacitor Cst. The amount of energy Uc supplied from the start capacitor Cst to the control circuits 1 and 1B before the power is switched to the power supply of the power storage unit Cm is Uc = Pt (4)
It becomes.
The start capacitor Cst is started until the voltage between the terminals of the start capacitor Cst drops from the full charge voltage, that is, the rated voltage Va [V] to the lower limit value Vss [V] of the allowable input voltage range of the DC-DC converter 3A. The amount of energy Us that can be supplied from the capacitor Cst to the control circuits 1 and 1B is Us = Cs (Va ² −Vss ² ) / 2 [J] (5)
It is.

Accordingly, charging of the power storage unit Cm is started with the charging current I [A] from the time when the start capacitor Cst is fully charged and driving of the control circuits 1 and 1B is started, and the output voltage of the power storage unit Cm is When Va [V] is reached, power is supplied from the start capacitor Cst to the control circuits 1 and 1B until the drive of the control circuits 1 and 1B is started by the energy from the power storage unit Cm. In order to continue supplying, at least Uc = Us must be established. Therefore, from the equations (4) and (5),
Pt = Cs (Va ² −Vss ² ) / 2 (6)
It becomes. Therefore, the capacitance Cs of the start capacitor Cst is Cs = 2Pt / (Va ² −Vss ² ) (7)
It becomes.

However, in actuality, a margin must be taken into account, so that the capacitance Cs of the start capacitor Cst is obtained by multiplying the safety factor S (> 1) and modifying the equation (7) as follows: Cs = 2SPt / (Va ² −Vss ² ) (8)
It is preferable that
For example,
Rated voltage Va = 2.7 [V] of each capacitor constituting power storage unit Cm,
Capacitance C = 600 [F] of each capacitor constituting the power storage unit Cm,
The number of capacitors constituting the power storage unit Cm is 10, and all are connected in series.
Rated voltage Va of the start capacitor Cst = 2.7 [V],
Lower limit value Vss of allowable input voltage range of DC-DC converter 3A
= 0.9 [V],
The charging current is I = 2 [A],
The power consumption of the control circuits 1 and 1B is P = 0.2 [W],
Safety factor is S = 10
Then, after the start capacitor Cst is fully charged, the time t [second] required until the expression (2) is satisfied is obtained from the expression (3):
t = CVa / (nI)
= 600 × 2.7 / (10 × 2)
= 81 [sec]
It becomes.

Therefore, at least the capacitance Cs of the start capacitor Cst is obtained from the equation (7):
Cs = 2Pt / (Va ² −Vss ² )
= 2 × 0.2 × 81 / (2.7 ² −0.9 ² )
= 32.4 / 6.48
= 5.0 [F]
However, if the safety factor S = 10, the capacitance of the start capacitor Cst is calculated from the equation (8):
Cs = 2SPt / (Va ² −Vss ² )
= 2 × 10 × 0.2 × 81 / (2.7 ² −0.9 ² )
= 50.0 [F]
It becomes.

The power storage device using the capacitor according to the present invention can be widely used in a power supply system in a region where there is no power transmission facility or in a remote island.

10, 10A, 10B, 10C Power storage device 1 using capacitors, 1B Control circuit 2, 2A Terminal voltage detection circuit 3, 3A, 3B Voltage conversion means, DC-DC converter DC DC power supply SW1 Break contact switch SW2 Make for charging Contact switch SW3 Discharge make contact switch Cst Sub power storage unit, start capacitor Cm Main power storage unit, power storage unit R Loads D0, D1, D2, D3, D4, D5, D6 Backflow prevention diode

Claims (7)

In a power storage device including a main power storage unit using a capacitor, a control circuit for controlling power storage from a DC power source to the main power storage unit, and discharging from the main power storage unit to a load,
In a power storage device including a sub power storage unit serving as a power source for the control circuit in an initial state in which power supply from the DC power source is started,
A capacitor is used for the sub power storage unit,
The main power storage unit is connected to the DC power source via a make contact switch for charging that performs a make contact operation,
A detection circuit for detecting a voltage between terminals of the sub power storage unit;
The control circuit starts to operate when power is supplied from the sub power storage unit after the inter-terminal voltage of the sub power storage unit detected by the detection circuit becomes equal to or higher than the operation voltage of the control circuit, and then the charging The make contact switch is closed, and the power storage from the DC power source to the main power storage unit is started, and predetermined power storage control is started.
The sub power storage unit is connected to the DC power source via a break contact switch that performs a break contact operation.
The control circuit is configured to open the break contact switch after the inter-terminal voltage of the sub power storage unit detected by the detection circuit becomes equal to or higher than a charging completion voltage. Power storage device. The load is connected to the main power storage unit via a discharge make contact switch,
The control circuit is configured to close the discharge make contact switch to be in a dischargeable state after the output voltage of the main power storage unit becomes equal to or higher than a predetermined dischargeable voltage. A power storage device using the capacitor according to 2. The power source of the control circuit is connected to the output voltage of voltage conversion means for converting the voltage between the terminals of the sub power storage unit into a predetermined operating voltage,
The voltage conversion means is configured to supply the output voltage as a power source of the control circuit after the voltage between the terminals of the sub power storage unit becomes equal to or higher than the predetermined convertible voltage. A power storage device using the capacitor according to any one of claims 2 to 3. 5. The power storage device using a capacitor according to claim 4, wherein the voltage conversion unit is a voltage conversion unit that converts an output voltage of the sub power storage unit into an operating voltage of the control circuit. 6. The power storage device using the capacitor according to claim 2, further comprising step-down voltage conversion means for stepping down the output voltage of the main power storage unit and charging the sub power storage unit. . The break contact switch is
A thyristor connected in series between the DC power supply and the sub power storage unit;
A depletion-type nMOSFET that is connected in parallel to the source and gate of the thyristor, is turned on when DC power supply starts, turns on the thyristor, and is turned off by a break control signal from a control circuit;
3. An enhancement-type nMOSFET that is connected in parallel to the source and drain of the thyristor, and is turned on after the thyristor is turned off by a break control signal from a control circuit, and then turned off. A power storage device using the capacitor according to claim 6. The break contact switch is
A thyristor connected in series between the DC power supply and the sub power storage unit;
An enhancement-type nMOSFET that is connected in parallel to the source and gate of the thyristor, is turned on by supplying a DC power supply to turn on the thyristor, and is turned off by a break control signal from a control circuit;
3. An enhancement-type nMOSFET that is connected in parallel to the source and drain of the thyristor, and is turned on after the thyristor is turned off by a break control signal from a control circuit, and then turned off. A power storage device using the capacitor according to claim 6.

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