JP2008029064A - Apparatus and method of charging electric double-layer capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure sufficient compensation time even for wide temperature change of a capacitor, and to extend the service life of the capacitor. <P>SOLUTION: A momentary-voltage-drop compensation device uses an electric double-layer capacitor 5, which is kept in a charged state by a step-up/step-down chopper 6, as a back-up power supply, and supplies electric power from an inverter 4 to a load 2 by short-time rating, if a momentary voltage drop occurs to a power source 1. In this device, a temperature detector 9 detects the present temperature of the capacitor, a temperature-voltage converter 10 converts the temperature into a voltage signal corresponding to the temperature detection value, and a function generator 11 obtains a voltage set value that satisfies the compensation time of short-time rating specification according to the temperature detection value of the capacitor. A charging control device 8 controls the charging voltage of the capacitor according to the voltage set value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a charging device and a charging method for an electric double layer capacitor in a power supply device that uses, as a backup power source, an electric double layer capacitor that is charged in advance by a charging device and supplies power to a load for a short time as required.

  Electric double layer capacitors (hereinafter referred to as “capacitors”) use electric energy stored in the electric double layer formed at the interface between activated carbon and electrolyte, and are large-capacity capacitors that can instantaneously charge and discharge farad order electric capacity. It is. Applications range from small-capacity products for memory backup to medium-capacity products for power assist in electric vehicles, and large-capacity products as alternative power sources for power storage batteries.

  The withstand voltage of the unit capacitor is determined by the electrolysis voltage of the constituent electrolyte (electrolyte, solvent), and is about 1.2 V for an aqueous electrolyte and 2-3 V for an organic electrolyte. . Since a capacitor is destroyed when a voltage equal to or higher than the solvent decomposition voltage is applied, a plurality of unit capacitors are connected in series for applications requiring a high voltage.

  In terms of structure, a capacitor has a wound type in which an electrode and a separator are wound in a spiral shape and accommodated in a cylindrical case, and a flat plate type in which the electrode separator is a flat plate. The flat plate type is an electrode, a separator, an electrode, a separator, A bipolar structure can be stacked alternately and is suitable for high voltage applications.

  For medium-capacity and large-capacity power storage applications, modules that combine units in parallel and in series are applied.

  On the other hand, capacitors have a long life, no maintenance, and high input / output characteristics compared to lead-acid batteries, and can store large volumes of electricity compared to electrolytic capacitors. It becomes a device that can be used as a backup power source for time outages. For this reason, a capacitor-type instantaneous voltage drop compensator (hereinafter referred to as a voltage sag compensator) has been studied as one of the applied products of capacitors.

  FIG. 4 shows an outline of the voltage sag compensator. In this figure, power is always supplied from the grid (commercial power source) 1 to the load 2 through the high-speed cutoff switch 3 (always commercial power supply method), and when an instantaneous voltage drop or instantaneous power failure is detected, it is instantaneous. Dissipation of the high-speed cutoff switch 3 and supply of electrical energy stored in the capacitor 5 through the inverter 4 make compensation for the sag.

  The compensation time of this device is usually considered to be 1 to 60 seconds depending on the capacitance of the capacitor 5, but most of the voltage drop can be covered within 2 seconds of compensation time. It is important to reduce the IR drop in order to flow a large current in a short time of about 2 seconds, and it is desirable that the internal resistance be small. However, in the actual voltage sag compensator, the synchronous pull-in time after double current is included. It is designed to have a discharge capacity of 2 to 3 seconds.

The charging control of the capacitor 5 is conventionally performed up to the rated voltage with a constant current or constant power, and then charged with a constant voltage. Furthermore, in order to increase the storage capacity, a method of continuing charging for a predetermined time after reaching full charge (for example, refer to Patent Document 1), a method of equally charging a plurality of capacitor cells connected in series, and the like have been proposed. Yes.
JP 2002-017051 A

  As described above, the charging control of the capacitor is performed up to the rated voltage with a constant current or constant power, and then charged with a constant voltage. When a capacitor charged to a certain voltage is discharged to a load as a backup power source, the voltage of the capacitor is charged as shown in FIG. When the discharge starts, the voltage drops by the IR (discharge current I × capacitor internal resistance R) drop from the constant voltage at the beginning of the discharge. Return to zero) by the IR drop.

  However, when the environmental temperature changes due to the difference in season or day and night, and this causes a change in temperature of the capacitor, the internal resistance of the capacitor increases at low temperatures, so that the IR drop increases and the time to drop to the operating voltage range (Dischargeable time) is shortened. On the contrary, when the temperature is high, the IR drop becomes small and the dischargeable time becomes long, and the compensation time changes depending on the temperature. In order to ensure a sufficient compensation time for the temperature change of the capacitor, it is necessary to provide a sufficient capacity for the capacitor, but problems such as an increase in the size of the capacitor and an increase in cost remain.

  Further, when the capacitor is placed in a high temperature applied state, the degree of progress of the deterioration becomes large, and there is a problem that the function is deteriorated before reaching the expected life.

  As countermeasures, it is conceivable that the capacitor is temperature-controlled, that is, heated by a heater at a low temperature and cooled by an air conditioner or a cooler at a high temperature. However, these measures require large-scale heaters and air conditioner facilities, which increase the running cost (power consumption), increase the cost of the equipment due to the additional equipment, and secure the installation space.

  The objective of this invention is providing the charging device and charging method of an electric double layer capacitor which solved said subject.

  In order to solve the above problems, the present invention detects the temperature of an electric double layer capacitor and charges the capacitor with a voltage setting value that satisfies the compensation time of the short-time rated specification according to the temperature detection value of the capacitor. It is characterized by the following apparatus and method.

(1) In a power supply apparatus that uses an electric double layer capacitor that is charged in advance by a charging apparatus as a backup power supply, and supplies power to a load at a short-time rating as required.
The charging device is:
Temperature detecting means for detecting a current temperature of the electric double layer capacitor;
Function generating means for obtaining a voltage setting value that satisfies the compensation time of the short-time rated specification according to the temperature detection value of the electric double layer capacitor by the temperature detection means;
Charging control means for controlling the charging voltage of the electric double layer capacitor according to the voltage setting value obtained in the function generating means;
A charging device for an electric double layer capacitor, comprising:

(2) The function generating means is provided with means for obtaining a voltage set value exceeding the rated voltage of the capacitor when the temperature of the electric double layer capacitor is low,
The charging device for an electric double layer capacitor, wherein the charging control means includes means for controlling a charging voltage of the electric double layer capacitor according to the voltage setting value obtained by the function generating means.

(3) In a power supply apparatus that uses an electric double layer capacitor that is charged in advance by a charging apparatus as a backup power supply and supplies power to a load at a short-time rating as required.
The charging device is:
A temperature detecting process for detecting a current temperature of the electric double layer capacitor;
In accordance with the temperature detection value of the electric double layer capacitor by the temperature detection process, a function generation process for obtaining a voltage setting value that satisfies the compensation time of the short-time rated specification;
A charge control step of controlling a charge voltage of the electric double layer capacitor according to the voltage setting value obtained in the function generation step;
An electric double layer capacitor charging method comprising:

(4) The function generation process includes a process of obtaining a voltage setting value exceeding a rated voltage of the capacitor when the temperature of the electric double layer capacitor is low;
The method of charging an electric double layer capacitor, wherein the charge control step includes a step of controlling a charge voltage of the electric double layer capacitor according to the voltage setting value obtained in the function generation step.

  As described above, according to the present invention, the temperature of the electric double layer capacitor is detected, and the capacitor is charged with a voltage setting value that satisfies the compensation time of the short-time rated specification according to the temperature detection value of the capacitor. Therefore, the following effects are obtained.

  Since the internal resistance of the capacitor decreases and IR drop decreases at high temperatures, the applied voltage can be lowered, the life of the capacitor is extended, and the compensation period of the instantaneous voltage drop compensator is extended.

  ・ Although the IR drop of the capacitor increases at low temperatures, the applied voltage can be increased by suppressing the deterioration reaction, and the operating temperature range on the low temperature side is expanded.

  -The operating temperature range is widened, and a capacitor temperature control device as an auxiliary machine such as an air conditioner is no longer required.

  FIG. 1 is an apparatus configuration diagram showing an embodiment of the present invention. This embodiment is a case where the present invention is applied to a capacitor type voltage sag compensator of 50 kVA-2 seconds compensation, and the same components as those in FIG.

  The step-up / down chopper 6 has its input / output terminal connected to the DC side of the inverter 4 to enable low-voltage charge control and high-voltage discharge control of the capacitor 5. Among them, the capacitor 5 is charged by using the smoothing capacitor C charged from the power source 1 through the recirculation diode of the inverter 4 as a DC power source and charging through the reactor L and the diode D2 by chopping control of the switch Q1. The capacitor 5 is charged by flywheel charging. For discharging from the capacitor 5, the discharge from the capacitor 5 to the smoothing capacitor C is obtained through the reactor L and the diode D 1 by chopping control of the switch Q 2, and power supply to the load 2 is enabled through the inverter 4.

  When the voltage drop compensation controller 7 detects a drop in the load voltage, the capacitor 5 is controlled to dissociate the high-speed cutoff switch 3 and to chop the switch Q2 so that the inverter 4 is synchronized with the frequency synchronized with the power source 1. AC output with a moderate voltage is obtained.

  The charging control of the capacitor 5 is performed by the charging control unit 8 by the chopping control of the switch Q1. In this charge control, a temperature detector 9 and a temperature-voltage signal converter 10 which are temperature detecting means for detecting the temperature of the capacitor 5, and a function generator for converting into a charge voltage set value corresponding to the temperature detection value T 11, and charging of the capacitor 5 is controlled by comparing the output of the function generator 11 with the voltage detection value of the capacitor 5.

  The temperature detector 9 obtains a temperature signal T by attaching a temperature sensor to a representative capacitor unit of the capacitors 5. The temperature-voltage signal converter 10 converts the temperature signal T into a voltage signal Vt corresponding to the temperature signal T. The function generator 11 has the function calculation or table data shown in FIG. 2 to obtain the charging voltage set value V *.

  The function characteristic of the charge setting voltage and the capacitor temperature shown in FIG. 2 is that the power converter (the step-up / step-down chopper 6 and the inverter 4) is discharged from the internal resistance corresponding to the capacitor temperature with a short-time rated power for the compensation time. ), The minimum charge setting voltage exceeding the usable lower limit voltage (for example, 160V) is obtained in advance. The higher the current temperature of the capacitor 5, the lower the charge setting voltage V *.

  In addition, when the temperature of the capacitor 5 changes greatly between day and night, when the temperature changes to a threshold level or higher, the charge control unit 8 appropriately executes discharge or charge control according to the temperature change, Set the charging voltage according to the current temperature. However, if the DC voltage at the smoothing capacitor C is expected to become an overvoltage for the discharge from the capacitor 5 due to the change in temperature, the discharge resistor is installed in parallel with the smoothing capacitor C or the inverter 4 is operated. Discharge with.

  FIG. 3 shows voltage characteristics when the capacitor 5 is discharged at rated power during the sag compensation by the charge setting voltage when the temperature of the capacitor 5 is 10 ° C. to 40 ° C. Here, the rated voltage of the capacitor is 400V, and at the capacitor temperature of 10 ° C., the rated voltage can be discharged for 3 seconds including the synchronous pull-in time. However, at 20 ° C., the charge setting voltage is 361V and 30 ° C. However, the specifications could be satisfied even if the voltage was reduced to 332V and 305V at 40 ° C.

  In general, the higher the applied voltage, the greater the degradation of the capacitor, the lower the lifetime, the longer the lifetime, the higher the temperature, the greater the degradation, and the lower, the longer the lifetime. Conventionally, the rated voltage (400 V in the above example) is applied to the capacitor 5 under any temperature condition. However, in the charging method of this embodiment, the voltage drop compensation device is lowered by lowering the charging voltage when the temperature is high. As a result, it is possible to significantly extend the service life.

  In addition, in the past, there was an example in which an air conditioner was attached to extend the life of the voltage sag compensator and controlled to 30 ° C. or less, but in this embodiment, the deterioration is suppressed by lowering the charging voltage when the temperature is high. As a result, the temperature control becomes unnecessary, and as a result, the price of the apparatus is lowered, and the power loss associated with the operation of the temperature control apparatus is eliminated, so that the running cost can be reduced. In addition, it is not necessary to secure an installation space for the temperature control device.

  Further, the above sag compensator is a device that satisfies the specifications at a capacitor temperature of 10 ° C. or higher. In this embodiment, the device was operated with a control for setting the charge setting voltage to 430 V at 5 ° C. As a result, the discharge time characteristic at 5 ° C. shown in FIG. The charge setting voltage 430V at this time is a voltage exceeding the rated voltage of the capacitor 5, but it is confirmed by a long-term evaluation test that the deterioration is suppressed by the low capacitor temperature and the life of the device is not shortened. It was done. By adopting this control, the operating temperature range of the capacitor type voltage sag compensator can be expanded to the low temperature side.

  In the above embodiment, the case where the electric double layer capacitor is applied to the instantaneous voltage drop compensator has been described. However, the control method and method of the present invention are not limited to the instantaneous voltage compensator, and the electric double layer is used. A power supply device that uses a capacitor as a backup power source and supplies power to the load for a short time as required, such as a hybrid vehicle that requires rapid operation with a charge / discharge time of less than 1 minute, or a voltage drop in the feeder in the electric railway field It can be applied to countermeasures and regenerative power absorption devices that prevent regenerative trains from being revoked, and the same effects can be obtained.

The example of the charging device of the capacitor which shows embodiment of this invention applied to the sag compensator. The function characteristic of the charge setting voltage and capacitor temperature in embodiment. Capacitor voltage characteristics when compensating for the set voltage and sag drop under each temperature condition. The figure which shows the outline | summary of a voltage drop compensation apparatus. An example of voltage / current characteristics during sag compensation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 Load 3 High speed interruption | blocking switch 4 Inverter 5 Electric double layer capacitor 6 Buck-boost chopper 7 Voltage drop compensation control part 8 Charge control part 9 Temperature detector 10 Temperature-voltage converter 11 Function generator

Claims (4)

In a power supply device that uses an electric double layer capacitor that is charged in advance by a charging device as a backup power source, and supplies power to the load at a short time as required,
The charging device is:
Temperature detecting means for detecting a current temperature of the electric double layer capacitor;
Function generating means for obtaining a voltage setting value that satisfies the compensation time of the short-time rated specification according to the temperature detection value of the electric double layer capacitor by the temperature detection means;
Charging control means for controlling the charging voltage of the electric double layer capacitor according to the voltage setting value obtained in the function generating means;
A charging device for an electric double layer capacitor, comprising: The function generating means is provided with means for obtaining a voltage set value exceeding the rated voltage of the capacitor when the temperature of the electric double layer capacitor is low,
2. The electric double layer capacitor charging device according to claim 1, wherein the charge control means includes means for controlling a charge voltage of the electric double layer capacitor in accordance with the voltage setting value obtained by the function generating means. . In a power supply device that uses an electric double layer capacitor that is charged in advance by a charging device as a backup power source, and supplies power to the load at a short time as required,
The charging device is:
A temperature detecting process for detecting a current temperature of the electric double layer capacitor;
In accordance with the temperature detection value of the electric double layer capacitor by the temperature detection process, a function generation process for obtaining a voltage setting value that satisfies the compensation time of the short-time rated specification;
A charge control step of controlling a charge voltage of the electric double layer capacitor according to the voltage setting value obtained in the function generation step;
An electric double layer capacitor charging method comprising: The function generation process includes a process of obtaining a voltage setting value exceeding a rated voltage of the capacitor when the temperature of the electric double layer capacitor is low,
4. The method of charging an electric double layer capacitor according to claim 3, wherein the charge control step includes a step of controlling a charge voltage of the electric double layer capacitor according to the voltage setting value obtained in the function generation step. .

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