JPH05199676A - Solar-battery power source - Google Patents

Abstract

PURPOSE:To effectively utilize the electric power of a solar battery by continuously supplementing the output shortage of the battery from commercial power supply when the sunshine becomes insufficient without causing any momentary break and without increasing the amount of hardware. CONSTITUTION:The title solar-battery power source which is combined with commercial power supply is constituted so that the electric power of the solar battery can be continuously and effectively utilized without increasing the amount of hardware by DC-connecting the solar battery with the commercial power supply through reverse current preventing diodes 3 and 4 and setting the operating voltage of the battery higher than the commercial power supply voltage, and then, using the battery in such a way that the power supply is obtained from the battery when sufficient sunshine is available and the electric power of the battery is supplemented from the commercial power supply when the sunshine becomes insufficient.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell power source which uses both a solar cell and a commercial power source.

[0002]

2. Description of the Related Art A solar cell is unstable as a power source because its output depends on the sunshine, and is normally stabilized in some way. Therefore, there are a method of temporarily storing the solar cell output in the secondary battery and taking out the output stably from the secondary battery, and a method of backing up using a commercial power source. There are a method of connecting with a solar cell and a method of switching both.

[0003]

The method using a secondary battery is disadvantageous in terms of cost, maintenance, and space, and therefore it is advantageous to back up using a commercial power source when there is a commercial power source. When backing up using a commercial power source, the method of switching to a commercial power source when there is insufficient sunshine has the problems that a momentary interruption occurs at the time of switching and the solar cell output cannot be fully utilized, so interconnection technology is technically superior. However, there is a problem that the hardware increases in terms of phase synchronization with a commercial power source, measures for system protection, etc., resulting in cost increase.

The present invention is intended to solve the above-mentioned problems, and continuously replenishes power from a commercial power supply without instantaneous interruption of output shortage when the sunshine is low and without increasing hardware. It is an object of the present invention to provide a solar cell power source that can perform

[0005]

According to the present invention, a commercial power source output terminal for rectifying and outputting a commercial AC input and a solar cell output terminal are connected in parallel via a backflow prevention diode to connect a commercial power source and a solar cell. It is a power supply system that makes direct current interconnection,
The solar cell operating voltage is set higher than the commercial power supply voltage.

[0006]

According to the present invention, a commercial power source for rectifying commercial alternating current and a solar cell are connected in parallel via reverse current prevention diodes to establish a direct current interconnection, and the operating voltage of the solar cell is set higher than the commercial power source voltage. , If the sunlight is sufficient, the output voltage of the solar cell will be higher than the commercial power supply voltage, the backflow prevention diode on the commercial power supply side will be turned off, and power will be supplied from the solar cell. When the output voltage drops to the commercial power supply voltage, the insufficient power is replenished from the commercial power supply, and when the output voltage of the solar cell becomes lower than the commercial power supply voltage, the backflow prevention diode on the solar cell side turns off and the commercial power supply Power is supplied from.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit block diagram showing the configuration of a solar cell power supply of the present invention, and FIG. 2 is a waveform diagram of each part. In the figure, 1 is a rectifier circuit, 2 is a smoothing circuit, 3 and 4 are backflow prevention diodes, 5 is a DC interconnection unit, and 6 is a voltage conversion circuit.

In FIG. 1, a commercial AC input for backup is rectified by a rectifier circuit 1 and smoothed by a smoothing circuit 2. Smoothing can be omitted depending on the required power quality. The output end of the smoothing circuit 2 and the output end of the solar cell are connected in parallel in the DC interconnection unit 5 via the backflow prevention diodes 3 and 4, respectively. Output of commercial power supply is 100V
In the case of AC, the maximum is 141V, so the normal solar cell output voltage (operating voltage) is set to about 141 to 150V. For that purpose, since the operating voltage of the solar cell is 70 to 80% of the open circuit voltage, the open circuit voltage may be set to about 200V. Of course, as the solar cell operating voltage,
The maximum power voltage may be used. After this,
The voltage conversion circuit 6 converts the voltage into a voltage required for the load, and if the load is AC drive, for example, orthogonal conversion is performed and output.

Next, the operation will be described with reference to the waveform chart of FIG. Since the DC interconnection point and the commercial power source side and the solar cell side of FIG. 1 are respectively prevented from backflow by the diodes 3 and 4, the voltage at the interconnection point C is at the commercial power source side A point and the solar cell side B point. Match the higher voltage.

Now, a case where the sunshine changes as shown in FIG. 2 (g) will be described. The voltage at point A on the commercial power supply side is 270
V (Fig. 2 (a)), and as shown in Fig. 2 (g), there is sufficient sunshine and the voltage at point B on the solar cell side is 280V (Fig. 2).
Assuming that (c), the voltage at the interconnection point C at this time is 28
It is 0 V (Fig. 2 (e)). In this state, since the backflow prevention diode 3 is cut off on the commercial power source side, no current flows (FIG. 2 (b)).
And at the interconnection point C, the electric current according to the sunshine flows (Fig. 2
(D)). When the operating voltage of the solar cell drops to 270v due to the decrease of sunshine (time t1 to t2), the backflow prevention diode 3 is turned on and the commercial power source supplies current (FIG. 2 (b)), and the solar cell side B Although the current at the point decreases (Fig. 2
(D)), the current at the interconnection point C is held at a predetermined value. After the time t2, when the sunshine is restored, the electric power is supplied again by the solar cell. Then, at timing t3, when the output voltage of the solar cell becomes 270 v or less due to lack of sunlight, the backflow prevention diode 4 is cut off and the current at the solar cell B point becomes 0 (FIG. 2 (d)), while the commercial power source A point 2 increases to a predetermined value and is supplied to the interconnection point C, so that the voltage and current at the interconnection point C are as shown in FIGS. 2 (e) and 2 (f).

Therefore, when the amount of sunshine decreases and the voltage of the solar cell decreases, the power is automatically replenished from the commercial power source side, and even when the power is supplied from the commercial power source,
When the sunshine is restored and the voltage on the solar cell side becomes higher than the voltage at point A, electric power is supplied from the solar cell. The maximum power point of the solar cell has a substantially constant voltage value, and the DC power can be effectively used by connecting the direct current with a voltage close to this.

FIG. 3 is a circuit block diagram in the case where the power source of the present invention is applied to a solar pump, and the same numbers as those in FIG. 1 indicate the same contents. Reference numeral 7 is a DC conversion circuit, and 8 is a variable speed inverter.

In this embodiment, in the maximum power tracking type solar pump which controls the rotation speed of the pump according to the output of the solar cell, the rotation speed of the pump is set to 1800 rpm to 3000 rpm in order to secure the minimum flow rate of the pump, and the sunshine is insufficient. Therefore, when performing backup with a commercial power source in case the minimum rotation speed cannot be secured by the solar cell alone in terms of electric power, the rotation speed of the pump is controlled using an inverter of variable speed control. The DC interconnection is applied.

Since a 3-phase 200V pump is used as the pump (not shown), a 3-phase 200VAC is also used as the commercial power source. Since the maximum voltage of three-phase 200VAC is 280V, if the solar cell has an open-circuit voltage of 400V and the DC input voltage range to the interconnection point is 280-400V, as described above, if there is sufficient sunshine, When the power is supplied from the battery and the sunlight is insufficient, the power is supplied from the commercial power source, so that the minimum flow rate of the pump can be secured.

[0015]

In general, the commercial power source is an alternating current and the solar cell is a direct current, and in order to use these two power sources together, at least one of them needs orthogonal conversion or alternating-current conversion. However, according to the present invention, the commercial power source is used. Just by properly adjusting the solar cell to the voltage at the DC interconnection point with and constructing a power source that continuously uses the solar cell power and effectively uses the solar cell power with almost no increase in hardware be able to.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing a configuration of a solar cell power supply of the present invention.

FIG. 2 is a waveform chart of each part.

FIG. 3 is a block diagram showing a power source for a solar pump.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rectifier circuit, 2 ... Smoothing circuit, 3, 4 ... Backflow prevention diode, 5 ... DC interconnection part, 6 ... Voltage conversion circuit.

Claims (1)

[Claims] 1. A power source system in which a commercial power source and a solar cell are connected in parallel by respectively connecting a commercial power source output terminal for rectifying and outputting a commercial AC input and a solar cell output terminal through a backflow prevention diode. Therefore, the solar cell power supply is characterized by setting the solar cell operating voltage higher than the commercial power supply voltage.