JPH09298837A - Capacitor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly distribute voltage without increasing the number of capacitors by connecting a constant voltage element in parallel to each capacitor which has breakdown voltage lower than the allowable voltage of the capacitor. SOLUTION: Capacitors C1 to C5 are connected in series and Zener diodes ZD1 to ZD5 as constant voltage elements are connected in parallel to each capacitor. Breakdown voltage of Zener diodes ZD1 to ZD5 is lower than the allowable voltage of the capacitors C1 to C5. When the capacitors C1 to C5 are charged at the same time, a voltage inversely proportional to each impedance is applied to the capacitors C1 to C5. When the terminal voltage of each capacitor C1 to C5 reaches the breakdown voltage of Zener diodes ZD1 to ZD5, the Zener diodes begin to conduct, and the voltage applied to the capacitors C1 to C5 is restricted below the allowable voltage and is charged to other capacitors C1 to C5. In this way, all the capacitors C1 to C5 are charged to the breakdown voltage of the Zener diodes ZD1 to ZD5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power storage device including a plurality of power storage devices for storing generated power such as solar cells.

[0002]

2. Description of the Related Art In a display device such as an electric road indicator, an electric signboard, and a gate light, a light emitting diode (LED) is used as a light emitting element.
There is one that uses. These display devices are provided with a solar cell, and are configured to charge the storage battery with the power generated by the solar cell in the daytime and take out necessary power from the storage battery for display at night.

When a high-voltage power storage device is constructed using a low-voltage power storage device, a plurality of power storage devices are connected in series. In this case, in order to equalize the voltages applied to the individual power storage devices, conventionally, power storage devices having similar characteristics (capacitance) are selected and combined to form a power storage device.

However, even if capacitors having similar capacitances are combined, individual capacitors have variations in characteristics such as capacitance and leakage current, and it is difficult to evenly distribute the voltage. For this reason, the rated voltage cannot be simply multiplied by several in series, and it is necessary to consider a certain amount of margin. Therefore, more capacitors than the number calculated by simple calculation are required.

On the other hand, as shown in FIG. 4, voltage distribution resistors r1 to r5 are connected in parallel to each of the capacitors C1 to C5 on the premise of variations in the characteristics of the capacitors themselves to equalize the voltage distribution. A power storage device is known.

[0006]

However, in order to improve the uniformity of voltage distribution in the capacitor using the resistance voltage dividing circuit, it is necessary to lower the resistance values of the resistors r1 to r5. When the value is lowered, the electric power discharged through the resistance element increases when the electric power is stored for a long time, and the storage efficiency deteriorates. Therefore, many capacitors are needed to supplement the electric power discharged through the resistance element. It is not preferable to use many capacitors because of high cost.

An object of the present invention is to provide a power storage device capable of uniformly distributing voltage without increasing the number of power storage devices.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 is an electricity storage device in which a plurality of electricity storage devices are connected in series, and when the breakdown voltage is in parallel with each electricity storage device and is equal to or less than the allowable voltage of the electricity storage device. It is configured by connecting a certain constant voltage element. According to the invention described in claim 1, when a plurality of capacitors connected in series are charged at the same time, a voltage inversely proportional to each impedance is distributed to each capacitor due to the difference in impedance of the charger. Then, when the voltage across each capacitor reaches the breakdown voltage of the constant voltage element, conduction of the constant voltage element begins, the voltage applied to the capacitor is limited to the allowable voltage or less, and another capacitor is charged. In the same manner, all the capacitors are charged to the breakdown voltage of the constant voltage element connected in parallel to each capacitor. Further, at a voltage that does not reach the breakdown voltage, almost no current flows in the constant voltage element, so that in the case of a low voltage, there is no loss due to a parallel element such as a resistor divider, and the power storage performance is improved. Furthermore, the derating can be reduced depending on the selection of the breakdown voltage of the constant voltage element.

According to a second aspect of the present invention, in a power storage device in which a plurality of power storage devices are connected in series, a light emitting diode whose breakdown voltage is equal to or lower than an allowable voltage of the power storage device is connected in parallel with each power storage device. In the invention according to claim 2, the light emitting diode generally has a relatively good constant voltage characteristic with respect to a capacitor having an allowable voltage of about 2 to 3 V, and is suitable for the present invention in terms of current capacity and price. ing. Depending on the type of the light emitting diode, by combining the light emitting diode with the diode in series, it is possible to make the voltage substantially equal to the allowable voltage of the capacitor. As described above, the power storage device can be realized by the number of power storage devices that is almost the same as the number of power storage devices calculated by simple calculation, and can be realized at a lower cost than before. Further, with such a configuration, an overvoltage protection circuit can also be used, which is also advantageous in terms of cost.

According to a third aspect of the present invention, in a power storage device in which a plurality of power storage devices are connected in series, a voltage dividing circuit provided corresponding to each power storage device and a divided voltage of each voltage dividing circuit are input. The output terminal includes a plurality of voltage follower circuits connected to each of the capacitors. According to the third aspect of the present invention, the divided voltage of the voltage dividing circuit is equal, and the voltage follower circuit operates so as to generate a voltage equal to the voltage of the voltage dividing circuit and equalizes the output voltage. Thus, the output current is flowed, and the voltage is equally distributed to the capacitors connected in series. At this time, in the voltage follower circuit, only a current corresponding to the variation of each series storage device flows, so that a small amount of power is sufficient and a large power loss does not occur. Further, by using a high resistance as the resistance of the voltage dividing circuit, the power loss can be suppressed to be small. As described above, accurate voltage distribution is possible, a built-in battery circuit can be realized with the same number of batteries as the number calculated by simple calculation, and the allowable voltage can also be used as it is as a calculated value. Therefore, the number of power storage devices can be reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments of the present invention will be described with reference to the drawings.

(I) First Embodiment FIG. 1 shows a circuit configuration of a power storage device according to a first embodiment of the present invention. In FIG. 1, capacitors C1 to C5
Are connected in series, and zener diodes ZD1 to ZD5 are connected in parallel to the capacitors C1 to C5 as constant voltage elements. The breakdown voltage of the Zener diodes ZD1 to ZD5 is less than or equal to the allowable voltage of the capacitors C1 to C5. In addition, the battery C
1 to C5 have the same capacitance, Zener diode ZD
1 to ZD5 have the same characteristics.

In the circuit of FIG. 1, the capacitors C1 to C5 are used.
When they are charged at the same time, due to the difference in impedance, a voltage inversely proportional to each impedance is applied to each capacitor C1 to C5. When the terminal voltage of each of the capacitors C1 to C5 reaches the breakdown voltage of the Zener diodes ZD1 to ZD5, the Zener diodes ZD1 to ZD5 start conducting,
The voltage applied to the capacitors C1 to C5 is limited to the allowable voltage or lower, and the other capacitors C1 to C5 are charged. As a result, all the capacitors C1 to C5 are charged to the breakdown voltage of the Zener diodes ZD1 to ZD5 connected in parallel to the capacitors C1 to C5.

Further, at a voltage which does not reach the breakdown voltage, almost no current flows through the Zener diodes ZD1 to ZD5, so that a loss due to a parallel element such as a resistance divider is small,
The power storage performance is improved. Furthermore, depending on the selection of the breakdown voltage of the Zener diode, the delaying can be reduced.

(II) Second Embodiment FIG. 2 shows a second embodiment of the present invention. In FIG. 2, capacitors C1 to C5 are connected in series and each capacitor C1 to C5
C5 has a light emitting diode LED1 to L as a constant voltage element.
ED5 is connected in parallel. Light emitting diode LED1
The breakdown voltage of LED5 is less than or equal to the allowable voltage of the capacitors C1 to C5. The capacitors C1 to C5 have the same capacitance, and the light emitting diodes LED1 to LED5 have the same characteristics.

In the circuit of FIG. 2, the allowable voltage is 2 to
The light-emitting diode L is connected to the capacitors C1 to C5 of about 3V.
The ED1 to LED5 have relatively good constant voltage characteristics and are suitable as constant voltage elements in terms of capacitance and price. Depending on the type of the light emitting diodes LED1 to LED5, by combining the light emitting diodes LED1 to LED5 with a diode in series, it is possible to substantially match the allowable voltage of the capacitors C1 to C5.

According to this embodiment, a power storage device can be realized with the same number of power storage devices as the number calculated by simple calculation, and can be realized at a lower cost than before. Further, with the above-described configuration, the overvoltage protection circuit can also be used, which is advantageous in terms of cost.

(III) Third Embodiment FIG. 3 shows a third embodiment of the present invention. In FIG. 3, capacitors C1 to C5 are connected in series, and capacitors C1 to C5 are connected.
The elements R1 to R5 are connected in parallel as a voltage dividing circuit. The outputs from the resistance elements R1 to R4 are supplied to the input terminals of the voltage follower circuits A1 to A4, and the outputs of the voltage follower circuits A1 to A4 are supplied to the capacitors C1 to C4. The capacitors C1 to C5 have the same capacitance, and the resistors R1 to
R5 has the same resistance value, and the voltage followers A1 to A4 have the same characteristics.

In the circuit shown in FIG. 3, the capacitors C1 to C5 are used.
In the case of charging / discharging, if there are variations in the capacitance, leakage current, or impedance of the capacitors C1 to C5, the voltages of the capacitors C1 to C5 will not be uniform, and the capacitors C1 to C5 will vary according to these variations. The distribution voltage of will also vary. However, the divided voltage is evenly output to the output terminals of the resistors R1 to R5. The outputs from the voltage follower circuits A1 to A4 are input to operate to generate an equivalent voltage at the output, and the output is supplied so as to make the output voltage uniform. Thus, the voltage is evenly distributed to the capacitors C1 to C5 connected in series. At this time, in the voltage follower circuits A1 to A4, only the currents responsible for the variations of the series capacitors C1 to C5 flow, so that a small amount of electric power is sufficient and a large power loss does not occur. In addition, by using high resistance elements as the resistance elements R1 to R5, it is possible to suppress power loss.

As described above, since accurate voltage distribution is possible, a power storage device can be realized with the same number of capacitors as the number calculated by simple calculation, and the allowable voltage can also be used as it is as a value that is simply calculated. The voltage utilization can be improved, and the number of capacitors can be reduced. Therefore, it is advantageous in terms of cost.

[0021]

As described above, according to the present invention,
Connect a constant voltage element in parallel with each capacitor, or
Since the voltage follower circuit is provided between the output from each voltage dividing circuit and the input of each capacitor, voltage distribution can be performed uniformly without increasing the number of capacitors.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a power storage device according to a first embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of a power storage device according to a second embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of a power storage device according to a third embodiment of the present invention.

FIG. 4 is a circuit configuration diagram of a conventional power storage device.

[Explanation of symbols]

 C1 to C5 Electric storage device ZD1 to ZD5 Zener diode LED1 to LED5 Light emitting diode r1 to r5 Resistance element R1 to R5 Resistance element A1 to A4 Voltage follower

Claims (3)

[Claims] 1. A power storage device having a plurality of power storage devices connected in series, wherein a constant voltage element having a breakdown voltage equal to or lower than an allowable voltage of the power storage device is connected in parallel with each power storage device. 2. A power storage device having a plurality of power storage devices connected in series, wherein a light emitting diode having a breakdown voltage equal to or lower than an allowable voltage of the power storage device is connected in parallel with each power storage device. 3. In a power storage device in which a plurality of power storage devices are connected in series, a voltage dividing circuit provided corresponding to each power storage device and an output terminal connected to each power storage device with the divided voltage of each voltage dividing circuit as an input. Power storage device including a plurality of voltage follower circuits that are provided.