JP2007282461A - Capacitor power accumulating device and control method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prolong the service life of a capacitor, as much as possible, when the capacitor such as an instantaneous voltage stepdown compensation device is specifically used at a high voltage, over a long time. <P>SOLUTION: A capacitor power accumulating device includes a capacitor to be charged as necessary from a charging power source and supplies power to a predetermined load that uses the capacitor. In a control method of the capacitor, where a rated voltage of the capacitor is Vr (e.g. 2.7 V) and the minimum accumulating power rate of the capacitor required in the load is El (e.g. 80% of initial accumulating power rate), the capacitor is charged at a first usage voltage V1 (e.g. 2.3 V) and the usage starts that has been set lower than the rated voltage Vr, the accumulating power rate in a fully charged voltage in the first usage voltage V1 is monitored; and if the accumulating power rate does not reach the minimum accumulating power rate El, even if the capacitor is fully charged, the charging voltage of the capacitor is increased up to a second usage voltage V2 (e.g. 2.5 V) set higher than the first usage voltage V1 within a range of not exceeding the rated voltage Vr. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a capacitor power storage device and a control method thereof, and more particularly to a technique for extending the service life of a capacitor (particularly an electric double layer capacitor).

The stored electric energy E of the capacitor increases and decreases in proportion to the square of the voltage V so that it can be expressed by 1/2 (C × V ² ) where C is the capacitance and V is the voltage. Capacitors are known as power storage elements that are much less susceptible to deterioration than other power storage elements such as secondary batteries that store electricity by chemical reaction, but may still deteriorate early depending on how they are used. However, the deterioration progresses over time. Incidentally, the capacitor has a faster deterioration when the working voltage is higher.

  By the way, in particular, a product requiring a long life is required to maintain product characteristics within a range of a constant change rate from an initial value over a long period of time. Among the capacitors, the electric double layer capacitor has a large capacitance, so it is used, for example, in a power system such as a driving power source of an electric vehicle or an instantaneous voltage drop compensator (so-called voltage sag compensator). In this field, it is necessary to keep the amount of electric power stored in the capacitor within the range of the constant change rate from the initial value as long as possible in order to cope with the sudden drop that occurs suddenly.

  An electric double layer capacitor is also used as an auxiliary power source for a drum heater of a copying machine, for example. In order to be able to cope with sudden start-up even in such an application, the amount of electric power stored in the capacitor is as much as possible. It is required to keep within a range of a constant change rate from the initial value over a long period of time.

  For this reason, in a voltage drop compensator or a drum heater of a copying machine, the capacitor is always kept in a floating (full charge) state for a long period of time. Therefore, there is a problem that the capacitor deteriorates early.

  In addition, although the problem in the above-described voltage sag compensator is not solved, in Patent Document 1, in order to prevent deterioration of the capacitor, the full charge voltage of the capacitor (particularly the ambient temperature) is determined. A technique for varying the working voltage) is disclosed.

JP 2002-142374 A

  Accordingly, an object of the present invention is to extend the service life of a capacitor as much as possible, particularly when the capacitor is used at a high voltage for a long period of time, such as a voltage sag compensator.

  In order to solve the above-mentioned problem, the present invention includes a capacitor that is appropriately charged by a charging power supply, and in a method for controlling a capacitor power storage device that supplies power to a predetermined load from the capacitor, the rated voltage of the capacitor is Vr, The minimum stored power amount of the capacitor required on the load side is set to El, and the capacitor is first charged with the first use voltage V1 set lower than the rated voltage Vr and used. When the stored power amount at the fully charged voltage at the use voltage V1 is monitored and the stored power amount does not reach the minimum stored power amount El even in the fully charged state, the charging voltage of the capacitor is set to the rated voltage. The second use voltage V2 is set higher than the first use voltage V1 within a range not exceeding Vr.

  In the method for controlling a capacitor power storage device, when the second use voltage V2 is lower than the rated voltage Vr, the charging voltage of the capacitor can be increased stepwise until the rated voltage Vr is reached.

  The present invention also includes a capacitor power storage device as a product invention. That is, the capacitor power storage device of the present invention includes a capacitor that is appropriately charged by a charging power source, and in the capacitor power storage device that supplies power to a predetermined load from the capacitor, voltage detecting means for detecting the voltage V of the capacitor; Current detection means for detecting a current I flowing from the capacitor to the load; calculating a discharge power amount of the capacitor from the voltage V and the current I; monitoring a stored power amount of the capacitor; and charging power source Control means for controlling the charging voltage for the capacitor, wherein the rated voltage Vr is the rated voltage of the capacitor and El is the minimum stored power amount of the capacitor required on the load side. Lower than the first use voltage V1 and the first use voltage within a range not exceeding the rated voltage Vr. At least two use voltages of a second use voltage V2 that is higher than V1 are set, and the control means charges the capacitor using the charge voltage of the charging power source as the first use voltage V1 and starts use. At the same time, the stored power amount at the full charge voltage at the first use voltage V1 is monitored, and if the stored power amount does not reach the minimum stored power amount El even in the full charge state, The capacitor is charged with the charging voltage as the second use voltage V2.

  According to the present invention, the capacitor is first charged to the first use voltage V1 (for example, 2.3 V) set lower than the rated voltage Vr (for example, 2.7 V), and the first use is started. When the stored power amount at the fully charged voltage at the voltage V1 is monitored and the stored power amount does not reach the minimum stored power amount El (for example, 80% of the initial value) required on the load side even in the fully charged state The capacitor charge voltage is increased to a second use voltage V2 (for example, 2.5 V) set higher than the first use voltage V1 within a range not exceeding the rated voltage Vr, thereby storing the capacitor. The service life of the capacitor can be extended until the amount of power increases and the amount of stored power at the second use voltage V2 becomes the minimum amount of stored power El again.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 4, but the present invention is not limited to this. FIG. 1 is a schematic diagram schematically showing the configuration of a capacitor power storage device according to the present invention, FIG. 2 is a graph showing the effect of the present invention, and FIG. 3 is a timing chart for explaining an example of a method for determining the amount of power stored in a capacitor. FIG. 4 is a flowchart for explaining the operation in this embodiment.

  First, as shown in FIG. 1, a capacitor power storage device 10 according to the present invention includes, as a basic configuration, a capacitor 11, a charging power source 12 that charges the capacitor 11, and a voltage detection unit 15 that detects a voltage V of the capacitor 11. And a current detecting means 16 for detecting a current (discharge current) I flowing from the capacitor 11 to the load 14 and a control means 17 for controlling the charging power supply 12. In this embodiment, the load 14 is a sag compensation device.

  As the capacitor 11, an electric double layer capacitor is preferably used. The capacitor 11 is connected to the charging power source 12 via a switch 18 controlled by the control means 17. The charging power source 12 is preferably a DC constant current power source. The capacitor 11 is connected to the load 14 via the discharge circuit 13. An inverter or a converter may be used for the discharge circuit 13.

  The control means 17 is composed of, for example, a microcomputer and is based on the voltage V of the capacitor 11 detected by the voltage detection means 15 and the discharge current I of the capacitor 11 detected by the current detection means 16 such as a clamp type ammeter. A calculation function is provided for calculating the amount of discharged power supplied to the load 14 and determining the amount of stored power E of the capacitor 11 from the amount of discharged power.

  It is also possible to obtain the stored electric energy E of the capacitor 11 by another method. Referring to the timing chart of FIG. 3, in this method, a capacity inspection cycle is inserted at regular intervals during the standby state.

In this capacity inspection cycle, the rated voltage of the capacitor 11 is Vr, the use voltage is V1 (<Vr), the intermediate voltage is Vm (V1 <Vm ≦ Vr), and the use lower limit voltage of the capacitor 11 is Vu. Is charged with a constant current I, and a time Δt until the voltage of the capacitor 11 rises from V1 to Vm is measured. The capacity C _{(t1) at} this time is obtained by the following equation (1).
C _(t1) = I × Δt / (Vm−V1) (1)
When C _(t1) is obtained, the capacitor 11 is discharged to the working voltage V1 and returns to the standby state.

On the other hand, assuming that the discharge time at the time of the instantaneous drop intended for the intended use is t ₂ and the capacity at that time is C _(t2) , the stored electric energy E of the capacitor 11 is obtained by the following equation (2).
_{E = C (t2) × (} V1-Vu) 2/2 ... (2)

If the capacity inspection cycle is inserted at regular intervals during standby, C _(t1) ≈C _(t2) , and therefore the time Δt until the voltage of the capacitor 11 rises from V1 to Vm is measured. Thus, the stored power amount E of the capacitor 11 can be obtained by the above equation (2) without discharging the capacitor 11.

When the capacitance of the capacitor 11 is C and the voltage is V, the stored electric energy E of the capacitor 11 can be expressed by E = 1/2 (C × V ² ). Along with this, the stored electric energy E gradually decreases. In this specification, it is determined that the life of the capacitor has been reached when the stored electric energy E does not reach a predetermined stored electric energy even in the fully charged state.

  Here, assuming that the rated voltage (nominal withstand voltage) of the capacitor 11 is Vr, and the minimum stored energy (lifetime stored energy) of the capacitor 11 required for operation on the load (instantaneous voltage drop compensation device) 14 side is El, control is performed. The means 17 controls the charging of the capacitor 11 as follows.

  If the rated voltage Vr of the capacitor 11 is 2.7 V, for example, and the minimum stored power amount El determined to be a lifetime is 80% of the initial stored power amount at the time of charging at the rated voltage Vr, Then, the capacitor 11 is charged by using the full charge voltage as a first use voltage of 2.3 V, which is lower than the rated voltage Vr, and the use is started.

  In this use process, when the storage capacity of the capacitor 11 is reduced to the minimum stored power amount El along with the discharge, the first use voltage is charged again at 2.3 V, and this charge / discharge is repeated thereafter.

  However, if the storage capacity of the capacitor 11 does not reach 80% of the initial stored power amount El, which is the minimum stored power amount El, even after charging at 2.3 V (full charge), the control means 17 sets the full charge voltage to 2. The first use voltage of 3V is switched to the second use voltage of 2.5V, which is higher than that, and the capacitor 11 is charged to continue use.

  Also in this use process, when the storage capacity of the capacitor 11 decreases to the minimum stored power amount El with discharge, the second use voltage is charged again at 2.5 V, and this charge / discharge is repeated thereafter. .

  However, if the storage capacity of the capacitor 11 does not reach 80% of the initial stored power amount El which is the minimum stored power amount El even when charged at 2.5 V (full charge), the control means 17 sets the full charge voltage to 2. The capacitor 11 is charged by further increasing from the second use voltage of 5 V to the third use voltage of 2.7 V, which is the rated voltage, and the use is continued.

  If the storage capacity of the capacitor 11 does not reach 80% of the initial stored power amount El, which is the minimum stored power amount El, even when fully charged at the rated voltage of 2.7 V, notifying means such as a lamp or buzzer (not shown). To prompt the user to replace the capacitor.

  In FIG. 2, as described above, the minimum stored power amount El determined to be the lifetime is 80% of the initial stored power amount during charging at the rated voltage Vr, and the operating voltage is 2.3 V → 2.5 V → 2. The lifetime characteristic graph at the time of using a capacitor | condenser by raising to 7V in steps is shown. FIG. 4 shows an operation flowchart in the above embodiment.

  As can be seen from this graph, according to the usage in the above embodiment, the first use voltage of 2.3V can be used for 10,000 hours, and then the use voltage is set to the second use voltage of 2.5V and the third use voltage of 2. By gradually increasing the voltage to 7V, the usage time can be further extended by 10,000 hours.

  In the above embodiment, the working voltage of the capacitor is increased stepwise from 2.3V → 2.5V → 2.7V, but the working voltage is increased on condition that the first working voltage is lower than the rated voltage. For example, the range from the first use voltage to the rated voltage may be increased step by step in increments of 0.1 V. In some cases, the range from the first use voltage to the rated voltage may be increased at once. May be raised.

The schematic diagram which shows schematically the structure of the capacitor electrical storage apparatus by this invention. The lifetime characteristic graph of the capacitor which shows the effect of the present invention. The timing chart for demonstrating the method of calculating | requiring the electrical storage electric energy of a capacitor. The flowchart which shows an example of operation | movement of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Capacitor electrical storage apparatus 11 Capacitor 12 Charging power supply 13 Discharge circuit 14 Load 15 Voltage detection means 16 Current detection means 17 Control means

Claims (3)

In a method for controlling a capacitor power storage device that includes a capacitor that is appropriately charged by a charging power source and that supplies power to a predetermined load from the capacitor,
First, the capacitor is charged with a first operating voltage V1 set lower than the rated voltage Vr, where the rated voltage of the capacitor is Vr and the minimum stored energy of the capacitor required on the load side is El. In addition to starting use, the amount of stored power at the full charge voltage at the first use voltage V1 is monitored. If the amount of stored power does not reach the minimum stored power amount El even in the fully charged state, A method for controlling a capacitor power storage device, comprising: increasing a charging voltage of the capacitor to a second usage voltage V2 set higher than the first usage voltage V1 within a range not exceeding the rated voltage Vr.   2. The capacitor power storage device according to claim 1, wherein when the second use voltage V <b> 2 is lower than the rated voltage Vr, the charging voltage of the capacitor is increased stepwise until reaching the rated voltage Vr. Control method. In a capacitor power storage device that includes a capacitor that is appropriately charged by a charging power source, and that supplies power to a predetermined load from the capacitor,
The voltage detection means for detecting the voltage V of the capacitor, the current detection means for detecting the current I flowing from the capacitor to the load, the discharge power amount of the capacitor is calculated from the voltage V and the current I, and Monitoring energy stored in the capacitor, and control means for controlling the charging voltage for the capacitor of the charging power supply,
Assuming that the rated voltage of the capacitor is Vr and the minimum stored energy of the capacitor required on the load side is El,
The control means includes at least two of a first use voltage V1 having a voltage lower than the rated voltage Vr and a second use voltage V2 having a voltage higher than the first use voltage V1 within a range not exceeding the rated voltage Vr. The working voltage is set,
The control means charges the capacitor with the charging voltage of the charging power supply as the first use voltage V1 and starts using the capacitor, and monitors the stored power amount at the full charge voltage at the first use voltage V1, The capacitor is charged with the charging voltage of the charging power source as the second use voltage V2 when the stored power amount does not reach the minimum stored power amount El even in a fully charged state. Power storage device.

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