JPS6130925A - Charger using solar battery as power source - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an efficient charging device using a solar cell as a power source.

(Conventional technology) Wind, solar, and wave power are used as power sources for observation equipment, radio wave relay equipment, lighting equipment, etc. in remote areas, remote islands, etc. where there is no commercial power supply equipment or where humans are not normally present. Although various methods such as power generation are used, solar cells using sunlight are widely used because they are advantageous in terms of cost and simplicity of equipment. Power sources in such places are precious, and it is preferable that they be charged efficiently and at a fast charging speed.

A conventional charging device of this type employs a circuit as shown in FIG. That is, the output from the solar cell 1 is supplied to the battery 3 through the reverse current prevention diode 2, and the battery 3 is charged.
For example, the above-mentioned observation equipment, lighting equipment, etc. Further, 5 is a circuit for preventing overcharging of the battery 3, which applies a signal to the gate of the thyristor 6 to short-circuit the output from the solar cell 1 and release it when the battery 3 reaches an overcharged state. .

(Problems to be Solved by the Invention) As shown in FIG. 1, the conventional charging device supplies the output obtained from the solar cell 1 to the battery 3 as it is, and takes into consideration the output characteristics of the solar cell 1. This causes problems in terms of charging efficiency and charging speed.

That is, in general, the output characteristics of a solar cell 1 are characteristic as shown in the solid line (voltage-current characteristic) and the broken line (power-voltage characteristic) in Figure 2. In Figure 2, the horizontal axis represents the current and the power (
output), the vertical axis shows the voltage, Voc is the open circuit voltage, Isc
is the short circuit current, Eel-Ee3 is the solar energy density, Pel, Pe2. Pe3 is the solar energy density Eel, Ee2. The power characteristics in Ee3 are shown.

As is clear from the figure, the output characteristics of the solar cell 1 are such that the higher the solar energy density on the ground, the greater the output, but the voltage required to obtain the maximum output is approximately constant depending on the energy density. The voltage required to obtain this maximum output is called the optimum operating voltage Yap. Further, the current flowing at this time is called the optimum operating current Iop.

As described above, in order to use solar energy most efficiently, it is essential to consider the optimal operating voltage and current, but conventional charging devices do not take these aspects into consideration. Since there was no charging efficiency,
There remained an issue with charging speed.

The present invention was made against the background of the above circumstances, and an object of the present invention is to provide a charging device that is small in size, has excellent charging efficiency and charging speed, and is capable of efficient charging.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a voltage detector that detects the output voltage of a solar cell, a predetermined optimum operating voltage of the solar cell, and a voltage detector that detects the voltage. A charging device using a solar cell as a power source includes a subtracter that outputs the difference between the output voltage of the solar cell and the output voltage of the solar cell, and a converter that varies the output of the solar cell and supplies it to the battery in response to the output of the subtracter. ing.

(Function) In this invention, the output voltage of the solar cell is constantly compared with a preset optimal operating voltage, and the output voltage of the solar cell is controlled by a DC/DC converter in response to the difference between the two types of pressure. Since the output of the solar cells is always maintained at the optimal operating voltage, not only charging efficiency is greatly improved, but also charging speed is increased.

(Example) Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

FIG. 3 is a block diagram showing an embodiment of the present invention,
The same symbols as in FIG. 1 indicate the same elements and circuits.

The voltage of the output of the solar cell l is detected by a voltage detector 7 and sent to a subtracter 8. Voltage setter 9 supplies optimal operating voltage Yap of solar cell 1 to subtracter 8 . A subtracter 8 converts the difference between the optimum operating voltage vop and the solar cell output voltage V to the amplifier 1.
Output to 0.

This amplifier IO obtains a current signal corresponding to the obtained differential voltage, amplifies it, and sends it to the subtracter 11. The subtracter 11 sends a difference signal between the output current signal from the amplifier 10 and the current flowing through the battery 3 detected by the current detector 13 to the amplifier 12.

The amplifier 12 amplifies this difference signal and performs pulse width modulation (P
WM) Output to the @ output circuit 14. The PWM @ output circuit 14 supplies pulse width modulated pulses corresponding to the current value from the amplifier 12 to the base drive circuit 16 that drives the DC/DC converter 15 . The DC/DC converter 15 has a PWM @ output circuit 14 and a base drive circuit 16.
In addition, it includes an NPN transistor 17, a flywheel diode 18, a choke reactor 19, and a capacitor 20.

This embodiment operates so that the current supplied to the battery 3 is detected by the current detector 13, and this current value is always maintained at the optimum operating current value of the solar cell 1. Subtractor 8.11
and amplifiers 10.12 carry out the said control, ie solar type? When the output voltage of Ikl is lower than the optimum operating voltage, the output current is reduced and the DC/DC
The output of the converter is changed, and the maximum output is always supplied to the battery 3 from the solar cell 1.

In the figure, 21 is a start/stop circuit that starts and stops the DC70C converter. It detects the voltage of the battery 3, and when the detected voltage falls below a certain value, the DC70C converter starts and stops.
Start the operation of the 0C converter. On the other hand, when the voltage exceeds the voltage value that would cause overcharging, the operation is stopped to prevent overcharging. The output of the start/stop circuit 21 is supplied to the PWM signal output circuit 14 to start and stop generation of the output signal. Further, this output may be used as an alarm signal.

(Effects of the Invention) As explained above, according to the present invention, maximum power can be extracted at all times and the battery can be charged at the optimal operating point of the solar cell, so charging efficiency is significantly improved. ,
Charging time is significantly reduced. As a result, it is possible to reduce the capacity of the battery relative to the load, which is also advantageous from an economic standpoint.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a charging device using a conventional solar cell, Fig. 2 is a diagram of output characteristics of the solar cell, and Fig. 3 is a block diagram showing an embodiment of a charging device using a solar cell according to the present invention. It is. 1...Solar cell 3...Battery 4...Load 7...Electricity/pressure detection circuit 8.11...
Subtractor 10.12...Amplifier 14...PWM signal output circuit

Claims (1)

[Claims] a voltage detector that detects the output voltage of the solar cell; a subtracter that outputs the difference between a predetermined optimal operating voltage of the solar cell and the output voltage of the voltage detector; A charging device that uses a solar cell as a power source and includes a converter that varies the output of the solar cell and supplies it to the battery.