JPH05292681A - Solar battery type power unit - Google Patents

Abstract

PURPOSE:To obtain a widely-usable solar battery type power unit, having a function of discriminating sunshine by a solar battery and a function of charging a built-in secondary battery from output terminals. CONSTITUTION:A container containing a secondary battery 2 and a control circuit and having external output terminals 8 and 9 connected with an output controlling semiconductor device 7, is united with a solar battery 1 in a body, and a solar battery type power unit which detects the variation of the voltage between both terminals of an adjusting resistor 4 connected in parallel with a thin-film solar battery, is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly versatile independent DC power supply device using a solar cell, a secondary battery and a control circuit.

[0002]

2. Description of the Related Art Conventionally, as a device that uses a secondary battery charged by a solar cell as a power source and controls the output to a load via a semiconductor element for output control, a marker lamp that automatically blinks an LED at night, a night time. A garden light that automatically lights up, a lighting for an outdoor clock, a lighting device that automatically lights up by a human body detection sensor, and an alarm device that emits a sound have been put into practical use.

All of these practical examples are devices in which a solar cell, a secondary battery, a circuit section, and a load device are arranged in an optimal structural location and electrically connected. Therefore, in order to simplify the design of load devices such as lights and signs, there is no technical idea of separating the DC power supply unit into a versatile power supply unit. Also, there is no need for an external output terminal. As an optical sensor for determining the sunshine, a CdS photoconductive element, a phototransistor, or the like is provided at an optimal position of the housing of the load device by providing a light-transmissive window of a waterproof mechanism. Also, as a measure against self-discharge of the secondary battery, use a new secondary battery shipped immediately before installation, charge the secondary battery with a charger before use, or charge it with a solar cell after installation. Measures are being taken, such as waiting for this to be done and making local adjustments.

[0004]

The first problem is a method for determining the sunshine. It is difficult to apply the conventional technology to a general-purpose solar battery power supply unit because the waterproof mechanism is expensive, the current consumption of the optical sensor is large, and the load device is not fixed.

The second problem is the discharge of the secondary battery. Charging is difficult because the secondary battery is integrated in the container.
In particular, a versatile power supply unit is easily stocked, and if it is completely self-discharged, it is not possible to confirm the performance at the time of selling the power supply unit or the operation after installing the device. For charging with a solar battery, for example, in the case of a power supply unit using a NiCd battery with a battery capacity of 1200 mAh and a solar battery with a maximum operating current of 100 mA, the battery capacity becomes almost 0 when stored at 40 ° C for 8 months. It takes about 3 days in summer to arrange the solar cells horizontally on a sunny day and about 1 week in winter to charge the battery. The artificial light source is low in practicality in terms of equipment, location, and power cost, and the separate terminal for quick charging directly connected to the secondary battery has a burnout due to a short circuit of the quick charging terminal and a failure or burnout due to confusion with the external output terminal. Occurs.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a highly versatile solar battery type power supply unit capable of sunshine discrimination and charging from an external output terminal.

[0007]

In order to achieve the above object, the present invention integrates a container accommodating a secondary battery and a control circuit with a thin film solar cell for charging, and through an output control semiconductor element. An external output terminal electrically connected to the secondary battery is provided, and a voltage change across both ends of the adjustment resistor connected in parallel to the thin film solar cell is detected to output only for a fixed time.

Further, in order to achieve the above object, the present invention provides
A container for accommodating a secondary battery and a control circuit is integrated with a solar cell for charging, and an external output terminal electrically connected to the secondary battery via an output controlling semiconductor element is provided, and the output controlling semiconductor element is provided. It is possible to charge from the external output terminal by connecting an external charging diode in parallel with.

[0009]

[Operation] When the voltage across the solar cell in which the adjusting resistor is connected in parallel reaches the set detection voltage equal to or lower than the voltage of the secondary battery due to the change in outdoor illuminance due to the rising and falling of the sun, the sunshine discrimination circuit composed of a logic IC or the like detects it. Then, the output control semiconductor element is turned on or off to control the output from the external output terminal.
Therefore, the external load is operated only at night or in the daytime, or the external load is operated for a certain time from rising sun or sunset by using a timer circuit or the like.

For charging, an external DC power source or various batteries are connected with the same polarity as the external output terminal. The output control semiconductor element connected to one of the positive electrode and the negative electrode of the external output terminal is reverse-biased, but the secondary battery is charged because current flows through the external charging diode. Further, the output control semiconductor element is not reverse-biased beyond the forward voltage of usually 1 V or less of the external charging diode, so that it is not damaged. In addition, the external charging diode prevents backflow from the secondary battery to the charging power source or various batteries. Further, even if the external load is an inductive load, the output control semiconductor element is protected from the counter electromotive force by the external charging diode.

[0011]

EXAMPLE A method for determining the sunshine, which is the first problem, uses a thin-film solar cell that can be used both for charging and as an optical sensor. A thin-film solar cell is a device in which cells are connected in series on a substrate by forming a junction with a P-type, N-type, or I-type semiconductor thin film on an insulating substrate and forming a pattern to obtain a practically necessary voltage. I do. A practical thin-film solar cell is an N-type C that doubles as a collector electrode and window material on a borosilicate glass substrate.
A compound thin film solar cell is used in which the dS thin film, the P-type CdTe thin film, the C thin film of the back electrode, and the like are sequentially formed by repeating printing and sintering. Further, a hydrogenated amorphous silicon solar cell in which a silane gas is decomposed by plasma CVD to form a PIN junction on a substrate such as glass is used. Hydrogenated amorphous silicon solar cells generate defects such as dangling bonds due to strong outdoor light.
The compound thin film solar cell is currently superior because the output decreases by 20%, the leak current increases, and the current-voltage characteristics at low illuminance necessary for sunshine discrimination also change. Film thickness is about 1
Thin-film solar cells with a large series resistance of 0 μm or less have a smaller fill factor than solar cells of bulk semiconductors such as single crystal silicon and polycrystalline silicon, so they have the same operation despite having a large band gap and a large open circuit voltage. Design with approximately the same number of cells connected in series to obtain the voltage. for that reason,
The open circuit voltage at low illuminance is higher than that of single crystal silicon or polycrystalline silicon.

FIG. 1 is a diagram showing the results of measuring changes in outdoor illuminance before and after sunset. Outdoor illuminance at sunset is almost 1
It is 001x, and shows a logarithmic change in illuminance with the passage of time on the horizontal axis. When the sun rises, the change with time is almost opposite to that shown in Fig. 1. FIG. 2 is a comparative measurement of current-voltage characteristics of a 19-cell series-connected thin-film solar cell and an 18-cell series-connected single-crystal silicon solar cell designed to charge a secondary battery rated at 6 V at an outdoor illuminance of 100 lx. It is a figure which shows a result. Shaded lines indicate characteristic variations. Polycrystalline silicon shows almost the same tendency as single crystal silicon, and in both cases, the open-circuit voltage has already dropped to 2.5 V or less at sunset and is below the detection voltage of the logic IC used. The open-circuit voltage of the solar cell is about 13V during sunny weather before the secondary battery is connected, and the detection voltage is 2.
It was 5-5V. On the other hand, in the case of the detection method according to the present invention, the detection voltage for determining the sunlight is required to be equal to or lower than the voltage of the secondary battery.

As the voltage of the secondary battery, the minimum common multiple of a NiCd battery having a single cell voltage of 1.2V, a nickel hydrogen secondary battery, a lead storage battery of 2V, and a lithium secondary battery of 3V is 6V.
From the compatibility of the secondary battery and the performance of the circuit element, the voltage of the solar battery type power supply unit is optimally 6V. The operating voltage of the solar cell after connection is usually 6 V or more because it is the sum of the forward voltage of the secondary battery and the backflow prevention diode, and the upper limit of the detection voltage of the logic IC is not recognized even in the overdischarged state at night. Is 5V.

When the detection voltage of the logic IC is set to 4V, and in FIG. 2, when the adjustment resistor of, for example, 50k ohm is connected in parallel to the thin film solar cell, the intersection of the alternate long and short dash line and the current-voltage characteristic is about 4V. Yes It is possible to detect. Further, the variation can be greatly reduced to 1/6 as compared with the case where the open circuit voltage is detected. The current flowing through the adjusting resistor is 0.2 mA or less, which is so high that it can be ignored during charging.

With respect to the self-discharge of the secondary battery which is the second problem, the present invention solves the above problem by charging from the external output terminal for output, and provides a solar battery type power supply unit which is versatile and convenient. Is provided.

The charging method from the external terminal is realized by connecting an external charging diode in parallel with the output controlling semiconductor element such as a transistor and in a direction in which the positive and negative sides are opposite to those at the time of output. As an external charging diode,
In addition to silicon diodes, use at least one Schottky diode with low voltage loss, and if the charging current may exceed the rating, connect a current limiting resistor with large allowable loss in series with the diode. It is necessary to use the output control semiconductor element as a switch for functions such as sunshine discrimination, blinking output, and short-circuit protection of the output terminal, which impedes charging from the external output terminal. On the other hand, in addition to self-discharge of the secondary battery, the base current and the like are consumed, and the charging function is further required.

FIG. 3 is a circuit diagram of a solar battery type power supply unit according to an embodiment of the present invention, which automatically outputs a blinking output at night and has a built-in output control circuit.

In FIG. 3, a solar battery 1 for charging and a secondary battery 2 are connected via a backflow prevention diode 3, and the voltage across the adjusting resistor 4 connected in parallel with the solar battery 1 is detected by a logic IC or the like. A sunshine discrimination circuit 5 for detecting sunset is connected. When the light receiving surface of the solar cell 1 becomes a predetermined darkness, the blinking output circuit 6 oscillates in response to the logic signal from the sunshine discrimination circuit 5, and the base current turns on / off the output control semiconductor element 7 such as an output transistor. .. At this time, predetermined power is supplied to the external output terminals 8 and 9 connected in series with the output control semiconductor element 7. External charging diode 1 connected in parallel with the output control semiconductor element 7
By setting 0, when an external load is not connected,
An external DC power source, which is set to a constant current with a voltage setting higher than the charging voltage of the secondary battery, is connected to the same polarity as the external output terminals 8 and 9 and charged. At this time, the output control semiconductor element 7 is reverse biased, but the maximum voltage is suppressed to about 1 V or less. In order to limit the charging current, it is possible to connect a series resistor to the external charging diode 10 or connect a constant current circuit using an FET. Further, in order to increase the current capacity and reduce the voltage drop, it is possible to use a plurality of diodes connected in parallel. In the embodiment of FIG. 3, since the NPN transistor is used as the output control semiconductor element 7, the collector is connected to the external output terminal 9 on the negative electrode side, but in the case of the PNP transistor, the emitter is connected to the external terminal 8 on the positive electrode side. The direction of the external charging diode 10 is also opposite. External charging diode 10
Selects a diode such as a Schottky diode that has a small voltage loss and an allowable current that is greater than the short-circuit current of the solar cell.
When a plurality of Ni-Cd batteries, nickel-hydrogen storage batteries, etc. are connected in series as the secondary battery 2, there is an upper limit to the generated current of the solar cell, so by selecting a current capacity that is approximately 2.5 times to 10 times that It can be used without a charge control circuit as in the third embodiment.

When a load device such as a marker lamp having a plurality of LEDs connected thereto is connected to the external output terminal, the LEDs automatically blink at night to function as a highly visible marker lamp. When an output circuit that continuously supplies a base current is used instead of the blinking output circuit 6, it can be used for a fire hydrant indicator light in which LEDs are continuously lit, night lighting, or the like. Further, the timer circuit is operated together with the sunshine determination, and the indicator light is turned on for 5 hours after sunset, or the pump is operated for 5 minutes at the time of rising sun to apply water.

By having the semiconductor element 7 for output control in this way, it is possible to perform intermittent output, control by a sensor, a timer, etc., and to provide the solar cell power source with the power saving function required.

4 and 5 show an embodiment according to the present invention,
It is an appearance perspective view of a solar cell type power supply unit. FIG. 4 is an external perspective view seen from the front side of the solar cell, and FIG. 5 is an external perspective view seen from the back side of the external output terminal. 4 and 5, the mounting frame 12 of the solar cell module 11
Is fixed to and integrated with the container 15 provided with the external output terminals 13 and 14 by using mounting screws 16. Container 15
A control circuit board having a semiconductor element for output control shown in the circuit diagram of the representative embodiment of FIG. 3 and a secondary battery are housed and electrically connected to the inside of the. Also, on the outside of the container 15,
A tapping hole 17 is provided for attaching a metal fitting or the like. The container 15 has a semi-sealed drip-proof structure in order to prevent generation of hydrogen gas due to overcharge of the built-in secondary battery and prevent dew condensation.

[0022]

According to the present invention, a general-purpose built-in secondary battery and a control circuit having a precise sunshine discrimination function with low current consumption without providing a special waterproof translucent window for an optical sensor. A highly efficient solar cell type power supply unit is realized.

Further, according to the present invention, the external output terminal can be used as it is as an external charging terminal so that the secondary battery can be rapidly charged externally even if the secondary battery self-discharges, and the external load is an inductive load. A safe, versatile and easy-to-use solar battery type power supply unit with a built-in secondary battery and control circuit is realized.

[Brief description of drawings]

FIG. 1 is a diagram showing a result of measuring a change in outdoor illuminance with respect to elapsed time before and after sunset.

FIG. 2 is a diagram showing comparative measurement results of current-voltage characteristics of solar cells in an outdoor illuminance of 100 lx.

FIG. 3 is a circuit configuration diagram of a solar battery type power supply unit that is an embodiment according to the present invention.

FIG. 4 is a front external perspective view of a solar battery type power supply unit according to an embodiment of the present invention.

FIG. 5 is a rear perspective view of a solar battery type power supply unit according to an embodiment of the present invention.

[Explanation of symbols]

 1 Solar Battery 2 Secondary Battery 3 Backflow Prevention Diode 4 Adjustment Resistor 5 Sunshine Discrimination Circuit 6 Flashing Output Circuit 7 Output Control Semiconductor Device 8, 9 External Output Terminal 10 External Charging Diode 11 Solar Cell Module 12 Frame 13, 14 External Output Terminal 15 Container 16 Mounting screw 17 Tapping hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mikio Murozono 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A container accommodating a secondary battery and a control circuit is integrated with a thin film solar cell for charging, and an external output terminal electrically connected to the secondary battery via a semiconductor element for output control is provided. A solar cell type power supply unit characterized by outputting a voltage for a fixed time by detecting a voltage change across both ends of an adjusting resistor connected in parallel to the thin film solar cell. 2. The solar battery type power supply unit according to claim 1, wherein a secondary battery having a rated voltage of 6 V is used and the voltage across the adjusting resistor is detected by a logic IC having a detection voltage of 5 V or less. 3. A container accommodating a secondary battery and a control circuit is integrated with a solar cell for charging, and an external output terminal electrically connected to the secondary battery via a semiconductor element for output control is provided. A solar battery type power supply unit characterized in that it can be charged from an external output terminal by connecting an external charging diode in parallel with the output control semiconductor element.