JPH05292684A - Charging storage power supply device for motive power - Google Patents

Abstract

PURPOSE:To provide a charge accumulated power device for motive power capable of storing charges efficiently by using capacitors, and supplying power to a load. CONSTITUTION:The charge storage power device for motive power is one which supplies power to a load by storing charges in a large-capacity capacitor, and it has a large-capacity capacitor C which is connected to a load and which supplies power to the load directly, a charging circuit 2 which charges the large-capacity capacitor C, a charging power source 1 connected to the large- capacity capacitor C through the charging circuit 2, a voltage detecting circuit 3 which detects the terminal voltage of the large-capacity capacitor C, and a charging limiting circuit S1 which discriminates that the terminal voltage detected by the detecting circuit 3 is a specified value or more and limits the charging of the large-capacity capacitor C. Consequently, it becomes possible to use the large-capacity capacitor C up to a maximum voltage designed, and raise electric energy storing efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power storage power supply device for power that stores electric power by using a large-capacity capacitor such as an electric double layer capacitor and supplies the power to a load.

[0002]

2. Description of the Related Art Exhaust gas from automobiles equipped with a gasoline engine has long been discussed as a subject of regulation due to global environmental problems. However, in reality, although the number of automobiles produced is still increasing, there is no prospect of reducing automobile emissions. Under such circumstances, electric vehicles equipped with batteries and solar cells have been attracting attention as vehicles that do not emit exhaust gas, and their early commercialization has become an urgent issue.

In recent years, some electric vehicles have been put to practical use for commercial vehicles such as delivery vehicles and cleaning vehicles that do not require long running distances or high speeds. Further, as a prototype vehicle, a vehicle capable of high-speed running of 100 km / h or more and continuous running of about 200 km has been reported. Further, a vehicle in which a solar cell is mounted on a vehicle to run while charging the battery, a hybrid drive vehicle using an engine and a motor, and the like have been proposed.

[0004]

One of the directions of an electric vehicle is independent four-wheel drive using a wheel motor without a gear mechanism such as an engine vehicle. Therefore, the drive mechanism is simplified, and the running property and the steering property can be solved by the coordinated control of the wheel motors. The biggest technical challenge in electric vehicles is to realize a driving power source, that is, a battery having a capacity comparable to that of an engine vehicle. First, in order to be sufficiently put into practical use as an electric vehicle, a battery of the same size and weight as the engine and capable of securing power equivalent to that of a gasoline engine is required. Moreover,
Is it possible to charge the battery at high speed or to replace a charged battery as easily as replenishing gasoline?

However, there is no conventional battery satisfying the above-mentioned requirements, and in particular, it takes a long time to charge, and in comparison therewith, it is a problem that it is larger and heavier than an engine. ing.

Further, an electric double layer capacitor having a smaller size and a larger capacity than that of a conventional capacitor has been developed and tends to be used for backup of a power source. A large-capacity capacitor such as this electric double-layer capacitor is advantageous in that it is lighter and has a longer life than a lead battery when it is considered as a power storage power source, but when the applied voltage becomes excessive with respect to the rating,
Immediately, it causes damage such as decrease in capacity and increase in leakage current. In addition, since internal resistance and withstand voltage are not sufficiently controlled, they have not been actively used.

An object of the present invention is to solve the above-mentioned problems, and an object thereof is to provide a power storage power supply device for power supply capable of storing power by using a capacitor with high efficiency and supplying power to a load. It is a thing.

[0008]

To this end, the present invention provides a power storage power supply device for storing power in a large-capacity capacitor to supply power to a load, the large-capacity capacitor being connected to the load and supplying power directly to the load, A charging circuit for charging the large-capacity capacitor, a charging power source connected to the large-capacity capacitor through the charging circuit, a voltage detection circuit for detecting the terminal voltage of the large-capacity capacitor, the terminal voltage detected by the detection circuit is a predetermined value or more. It is characterized by being provided with a charge limiting circuit which determines that the charging has been completed and limits the charging of the large-capacity capacitor. Further, the charge limiting circuit has a switching means that is inserted and connected in series to the charging circuit, and is configured to cut off the charging circuit by determining that the terminal voltage has exceeded a predetermined value, or a large-capacity capacitor. It has a bypass circuit in parallel with, and is configured to bypass the charging current by determining that the terminal voltage has become equal to or higher than a predetermined value.

[0009]

In the power storage power supply device for power of the present invention, a large-capacity capacitor connected to the load to directly supply power to the load, a charging circuit for charging the large-capacity capacitor, and a charging circuit connected to the large-capacity capacitor through the charging circuit. For the power supply, the voltage detection circuit detects the terminal voltage of the large-capacity capacitor, and the charge limiting circuit determines that the terminal voltage has exceeded the specified value and limits the charging of the large-capacity capacitor. Can be used up to the designed maximum voltage, and the storage efficiency of electric energy can be increased.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing one embodiment of a power storage power supply device for power supply of the present invention, 1 is a charging power supply, 2 is a charging circuit, 3 is a voltage detection circuit, 4 is a load, C is a large-capacity capacitor, V
r and Vr 'are reference voltages, and S1 and S2 are switches.

In FIG. 1, a large-capacity capacitor C connected to the load and supplying electric power directly to the load is a switch S1,
It is connected to the charging power source 1 via the charging circuit 2 and also connected to the load 4, and supplies power directly to the load 4. The charging power supply 1 is, for example, a commercial power supply for charging the large-capacity capacitor C, and the charging circuit 2 is provided with a voltage converting means such as an inverter. The voltage detection circuit 3 detects whether or not the terminal voltage of the large-capacitance capacitor C is at the full charge level by comparing with the reference voltages Vr and Vr '. When the full charge level is reached, the switch S1 is turned off and the switch is turned on. Turn on S2. Therefore, by setting the reference voltage Vr + Vr 'to the full charge level, the switch S1 is kept in the ON state until the terminal voltage of the large-capacity capacitor C reaches the full charge level, and the charging power source is supplied via the charging circuit 2. The large-capacity capacitor C is charged from 1, and when the full-charge level is reached, the switch S1 is turned off to stop the charging, and the voltage applied to the large-capacity capacitor C is prevented from becoming excessive with respect to the rating. At this time, a certain dead band is set for the on / off control of the switch S1 by turning on the switch S2 and short-circuiting a part of the reference voltage Vr '.

As described above, when the capacitor is used as a power source, if the applied voltage becomes excessively large with respect to the rating of the capacitor, the capacitance of the capacitor is reduced and the leakage current is increased. In order to deal with this, it is usual to design and manufacture the capacitor with a margin in decomposition voltage, withstand voltage and the like. However, since the electric energy stored in the capacitor is proportional to the square of the voltage, it is advantageous to use even a high voltage.
From such a viewpoint, in the present invention, since the terminal voltage of the capacitor is constantly monitored and limited by the switch S1, the capacitor can be used up to its maximum voltage, and a larger amount of electric energy can be effectively stored.

FIG. 2 is a diagram showing another embodiment of the power storage power supply device for power according to the present invention. ZD is a constant voltage element, TR is a transistor, and R1 and R2 are resistors. In the embodiment shown in FIG. 2, the series circuit of the transistor TR and the resistor R2 is connected as a bypass circuit for the charging current of the large capacity capacitor C, and the terminal voltage of the large capacity capacitor C is limited to the voltage of the constant voltage element ZD. It is composed. With this configuration,
When the voltage of the constant voltage element ZD is selected as the voltage when the large capacity capacitor C is at the full charge level, the transistor TR becomes conductive at the full charge level so that the terminal voltage of the large capacity capacitor C is maintained at the full charge level. The conductivity of the transistor TR changes. That is, it constitutes a voltage limiter.

FIG. 3 is a view showing still another embodiment of the power storage device for power of the present invention, 11 is an AC power supply for charging,
12 is a charging DC power supply, 13 to 15 are charging circuits, 16 is a charging control circuit, 17 is a load, CA and CB are large-capacity capacitors, and Vr is a reference voltage.

In FIG. 3, the large-capacity capacitor CA is
It is a power supply for load power supply that is connected to the load 17 and supplies power directly to the load 17, and the power density is not so high,
A capacitor with low internal resistance is used. The large-capacity capacitor CB is a power source for charging the large-capacity capacitor CA, and has an internal resistance not so low as compared with the large-capacity capacitor CA, but a capacitor having a large power capacity to volume or weight ratio is used. The charging circuit 15 is a circuit for charging the large-capacity capacitor CA from the large-capacity capacitor CB, and is composed of voltage conversion means such as an inverter. The charge control circuit 16 includes a large-capacity capacitor CA.
Of the terminal voltage, that is, the load voltage, is detected and compared with the reference voltage Vr. In the case of the reference voltage Vr, the large-capacity capacitor C
The charging circuit 15 is controlled so that the large capacity capacitor CA is charged from B. The reference voltage Vr is set to the full charge level of the large capacity capacitor CA.

The charging AC power supply 11 is, for example, a normal commercial AC power supply, and the charging DC power supply 12 is a DC power supply such as a solar cell. The charging circuits 13 and 14 are circuits that convert and rectify the voltage to charge the large-capacity capacitor CB. Of course, the charging circuits 13 and 14 may be composed of voltage conversion means such as an inverter.

As described above, the required power source capacity is divided into two power source sections consisting of the large-capacity capacitor CA and the large-capacity capacitor CB, and it depends on the conditions such as the load. 4. The large-capacity capacitor CB has a remaining capacity of 3/4. By keeping the large-capacity capacitor CA at the full charge level as much as possible, the load can always be supplied with a relatively constant voltage from the power source (large-capacity capacitor CA) having a low internal resistance. Since a power supply (large-capacity capacitor CB) having a large internal resistance, which is easy to manufacture, is frequently used, the overall volume and weight can be reduced.

FIG. 4 is a diagram showing a configuration example of the charge control unit. The comparator 21 compares the terminal voltage of the large-capacity capacitor CA with the reference voltage Vr and turns on the charging circuit 15 when the reference voltage Vr is large. Is output, the terminal voltage of the large-capacity capacitor CA is divided and detected by the resistors R1 and R2, and the comparator 2 is connected via the resistor R13.
A detection signal of the terminal voltage is input to 1. Also, the resistance r
Is a resistance for current detection, and the charging circuit 15 detects the charging current by the resistance r and controls the charging current to be constant. That is, the charging circuit 15 is turned on / off by the output signal of the comparator 21, and the charging current is controlled by detecting the current by the resistor r. Large capacity capacitor C
B is a power source with a large internal resistance, and when it is charged with a large current, the loss becomes large. Therefore, it is possible to reduce the loss by limiting the charging current.

Next, the electric double layer capacitor used in the present invention will be described. The electric double layer capacitor uses activated carbon which has a large specific surface area and is electrochemically inactive as an electrode material, and utilizes a large electric double layer capacity in combination with an electrolyte. ,
An electric double layer is formed and charged until the decomposition voltage of the electrolyte is reached, and when the decomposition voltage is exceeded, a current starts to flow. Therefore, the withstand voltage of the electric double layer capacitor is regulated by the decomposition voltage of the electrolyte, and the decomposition voltage of the aqueous electrolyte having high conductivity is about 1.2 to 1.3V. Electric double layer capacitors with a withstand voltage of several V and a capacity of several F (farad) are commercially available, and there are various internal resistances of 100Ω to 10Ω. ．
5V, 240F, 0.1Ω has been announced.

As described above, in the conventional electric double layer capacitor, when it is used as a power storage power source, it is difficult to have a low breakdown voltage and a relatively large internal resistance. Moreover,
Compared to electrochemical cells such as lead batteries and nickel-cadmium batteries, even in electric double-layer capacitors, the latter is about 20 times larger in terms of weight and energy, and because it has a large internal resistance, it cannot be used for high power. .. for that reason,
In order for an electric double layer capacitor to be able to compete with a storage battery, it is basically to increase the energy density and reduce the internal resistance.

In general, when a voltage higher than the decomposition voltage is applied to a capacitor, it causes damage such as a decrease in capacity and an increase in leakage current. Therefore, a voltage equal to or lower than the decomposition voltage is used as the breakdown voltage. This decomposition voltage is 1.23 for water.
V, 1.25V in the case of a commonly used organic electrolyte
It is a degree. On the other hand, as the solvent of the chemical material, there are many organic electrolytes having a decomposition voltage of 6 V or more. However, when actually used in an electric double layer capacitor, the decomposition voltage is rated at 1.2 to 1.3V.
This is believed to be due to impurities including water.

Then, for example, when solute was put in propylene carbonate and electrolyzed, it was found that the decomposition voltage was gradually increased from about 1 V or more at first, though it was varied. In other words, even if a high-purity electrolytic solution contains water and impurities, the initial decomposition voltage is about 1 V or more, but when this is electrolyzed, the impurities are decomposed and separated, and the original decomposition voltage is reached. Can be obtained. Therefore, when an electrode applied with a DC voltage slightly lower than the theoretical decomposition voltage is inserted into the target high-purity electrolytic solution, impurities lower than the decomposition voltage are electrolyzed and separated. The withstand voltage can be increased by refining.

On the other hand, since various foreign substances are naturally adsorbed on the porous electrode such as activated carbon or activated carbon fiber,
When these are used as they are as electrodes, various foreign substances are eluted into the electrolytic solution when the electrodes are immersed in the electrolyte. Therefore, even if the high-purity electrolytic solution is purified as described above, the purity is lowered and the decomposition voltage is lowered. Therefore, when the electrode is evacuated while being heated in a vacuum container in advance with high frequency, cooled as it is, and impregnated with the electrolytic solution in vacuum, foreign substances can be removed, and deterioration of the purity of the electrolytic solution can be prevented.

As the structure of the electrode for lowering the internal resistance, activated carbon fiber is slightly excessively activated to obtain a fiber having a slightly large microbore. Then, these fibers are aligned and arranged almost in close contact with each other in a plate shape, and a metal such as aluminum is vapor-deposited or melted on both ends and a back surface thereof, or connected with a conductive paint or the like to attach a lead wire. This makes it possible to obtain an electrode having a low electric resistance and a high density. These electrodes are impregnated with an electrolytic solution and are opposed to each other via a load-insulating porous separator, and are used as positive and negative electrodes.

As described above, by refining the electrolytic solution and manufacturing and assembling the activated carbon electrode, an electric double layer capacitor having a high withstand voltage can be obtained and the internal resistance can be reduced. As a result, if the withstand voltage is increased four times, for example, the amount of electric power that can be stored can be increased by 16 times the square. For example, the prototype of the electric double layer capacitor of 2.5V, 240F, 0.1Ω described above has a volume of 35 mmφ ×
It is 50mm, and the electric power that can be taken out to 1V is 0.17
Since it is 5 WH, a volume of about 6 m ³ is required to secure the electric power of 20 KWH required for the power source of the electric vehicle. However, the volume can be reduced to 1/16 by simply increasing the withstand voltage four times. In the present invention, by selectively using such an electric double layer capacitor, it is possible to increase the stored electric energy, reduce the internal resistance, reduce the power loss, and improve the power supply efficiency.

The present invention is not limited to the above embodiment, but various modifications can be made. For example, in the above-described embodiments, the circuit on / off means is simply shown as a switch, but a semiconductor switching element such as a thyristor or a transistor, or other switching means may be used. Needless to say, it may be used not only as a power source for an electric vehicle, but also as a power source for an electric welder or other electric power unit or a portable power source.

[0027]

As is apparent from the above description, according to the present invention, the charge of the capacitor is controlled by the terminal voltage to charge it to the full charge level, so that the electric energy can be effectively stored and the power storage power source can be stored. The supply efficiency of the device can be increased. Further, since it is possible to prevent the capacitor from being applied with an excessive voltage with respect to the rating, it is possible to prevent damage such as a decrease in the capacity of the capacitor and an increase in leakage current even when the capacitor is used as a power storage power source.

[Brief description of drawings]

FIG. 1 is a diagram showing one embodiment of a power storage power supply device for power of the present invention.

FIG. 2 is a diagram showing another embodiment of the power storage power supply device for power of the present invention.

FIG. 3 is a diagram showing still another embodiment of the power storage power supply device for motive power of the present invention.

FIG. 4 is a diagram illustrating a configuration example of a charge control unit.

[Explanation of symbols]

1 ... Charging power source, 2 ... Charging circuit, 3 ... Voltage detection circuit, 4
... load, C ... large-capacity capacitor, Vr, Vr '... reference voltage, S1, S2 ... switch

Claims (3)

[Claims] 1. A power storage power supply device for power storage that stores electricity in a large-capacity capacitor to supply power to a load, wherein the large-capacity capacitor is connected to the load to supply electric power directly to the load, and a charging circuit that charges the large-capacity capacitor. A charging power source connected to a large-capacity capacitor through a charging circuit, a voltage detection circuit that detects the terminal voltage of the large-capacity capacitor, and a large-capacity capacitor that determines that the terminal voltage detected by the detection circuit has exceeded a predetermined value. A power storage power supply device for motive power, comprising a charge limiting circuit for limiting the charging of the battery. 2. The charge limiting circuit has a switching means that is inserted and connected in series to the charging circuit, and is configured to cut off the charging circuit when it is determined that the terminal voltage has reached a predetermined value or higher. The power storage power supply device for power according to claim 1. 3. The charge limiting circuit has a bypass circuit in parallel with the large-capacity capacitor, and is configured to bypass the charging current when it is determined that the terminal voltage has exceeded a predetermined value. The power storage power supply device according to claim 1.