JPH07281774A - Solar cell system - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a solar cell system, and more particularly to a household electric appliance driven by a direct current using an inverter, and its purpose is to use the solar cell as an auxiliary power source in combination with a commercial AC power source. In this case, it relates to effective use of solar cell energy. A plurality of rectifier circuits for rectifying a commercial power supply, and a plurality of inverter circuits connected to the output of the rectifier circuits.
In a plurality of home electric appliances driven by the output of the inverter circuit, a solar cell which receives sunlight between the plurality of rectifier circuits and the plurality of inverter circuits to generate an electromotive force, A solar cell system comprising an active power control device and a power distribution unit for distributing optimum active power to the plurality of home electric appliances.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to household electric appliances driven by direct current using an inverter, and more particularly to effective use of solar cell energy when a solar cell is used as an auxiliary power source in combination with a commercial AC power source. Is.

[0002]

2. Description of the Related Art In recent years, a system for converting solar energy into electric power by using a solar cell has been put into practical use. Solar cells have recently attracted a lot of attention as a clean energy source, but their power generation capacity changes according to the illuminance of sunlight, and because they are current-type cells, the generated power decreases when they are overloaded. There is a problem and how to use it is one of the important issues. However, against the background of the increasing tendency of electric power demand and the like, the study of application as an auxiliary power source for a room air conditioner and the like, which consumes a large amount of power, has become popular, and for example, a circuit configuration shown in FIG. 6 has been proposed.
FIG. 6 shows that the commercial power input 1 is assisted by connecting the solar cell 5 to the connection point of the converter section 3 of the conventional inverter air conditioner and the inverter section 4 composed of six power transistors through the backflow prevention diode 6. To do. According to this configuration, since the conventional inverter room air conditioner and the solar cell 5 are connected via the backflow prevention diode 6, the solar cell 5 does not become a load of the commercial power supply 1, and the solar cell The output of 5 does not flow back to the commercial power supply side 1. However, in this configuration, the solar cell 5
There is no control to efficiently convert the energy in the power into electric power and extract it.

FIG. 7 shows the VI characteristics of a solar cell. As shown in FIG. 7, a solar cell generally has a constant current operating region and a constant voltage operating region, and the maximum current (current value in the constant current operating region) changes according to the illuminance. However, inverter room air conditioners generally use voltage-driven inverters, and since the load changes greatly depending on the outside air temperature and the air volume of the indoor and outdoor fans, it is difficult to operate the solar cell independently for stable operation. is there. FIG. 7 shows the VI characteristics of the solar cell according to the illuminance of sunlight and the critical load line in each state. In order to operate the voltage source inverter stably, the voltage source inverter must be used in a load state below the critical load line regardless of changes in sunlight illuminance, in other words, the solar cell must be used in the constant voltage operation region. For loads above the critical load line, the voltage drops sharply and the compressor is stopped immediately. Therefore, in a load state above the critical load line, a commercial power source is connected in series with the solar cell to increase the power supply. However, in the load state below the critical load line, in order to use the energy of the solar cell as the maximum state, it is necessary to control so that the product (V × I) of the solar cell VI characteristics according to the illuminance of the sunlight becomes maximum. I won't.

As a method for maximizing the energy of the solar cell, Japanese Patent Laid-Open No. 3-226237 carries out maximum power tracking control. This will be described below with reference to FIG. 1 is 50
/ 60 Hz commercial AC power supply, 7 is an AC / DC converter as a first power converter that converts AC power of the power supply 1 into DC, and 8 is a first power supply 1 connected to the power supply 1 via the converter 7. As a load of an inverter air conditioner, 9 is connected to a connection point A between the converter 7 and the air conditioner 8 and supplies a DC power to the air conditioner 8, and a solar battery 10 reversely converts the DC power of the battery 9 into AC. An inverter as a second power converter, 11 detects an output current I and an output voltage V of the battery 9 and outputs an output voltage of the converter 7 and an inverter 10 so that the maximum generated power can be taken out from the battery 9. The maximum power tracking device for controlling the input voltage, 12 is a changeover switch 13 for switching the connection to the commercial AC power supply 1 or the inverter 10 in the daytime and the nighttime.
Is an electric water heater as a second load which is connected to the output side of the inverter 10 via the switch 10 and is connected to the power source 1 at the interconnection point B via the changeover switch 13.

In the power supply system having the above structure, the AC power of the commercial AC power supply 1 is converted into DC power by the converter 7 and supplied to the inverter air conditioner 8. The solar cell 9 is connected to the interconnection point A and supplies electric power to the air conditioner 8 in parallel with the output of the converter 7. At this time, the maximum power tracking device 11 multiplies the detected value of the output voltage V of the solar cell 9 and the output current I and controls the output voltage of the converter 7 so that this value, that is, the power value is always maximized. Therefore, the voltage at the interconnection point A is always the optimum operating voltage.

When the demand power of the inverter air conditioner 8 exceeds the power generated by the solar battery 9, the power generated by the solar battery 9 is maximized to be supplied to the air conditioner 8 and the shortage is supplied to the commercial AC power supply 1. Supplied from on the other hand,
When the power generated by the solar cell 9 exceeds the power demanded by the air conditioner 8, surplus power is generated by the solar cell 9, but the converter 7 blocks reverse power flow of this surplus power to the commercial power source 1 side. Therefore, as it is, the solar cell 9 cannot be operated at the maximum operating point. In this case, the inverter 10 is operated to supply electric power from the solar cell 9 to the electric water heater 12 to absorb the surplus electric power.

[0007]

Since the power generation capacity of a solar cell greatly changes depending on the irradiation amount of sunlight, it can be applied to loads such as room air conditioners that require electric power regardless of the irradiation amount of sunlight. , Cannot be used alone and must be used in coordination with commercial power sources. When the amount of sunlight is large enough to generate more power than the room air conditioner requires, the solar cell should be driven independently, and when the generated power drops due to cloudy weather, it should be driven with a commercial power source. However, in the configuration of Japanese Utility Model Laid-Open No. 3-3021 as described above, control for efficiently converting the energy of the solar cell 5 into electric power and taking out the electric power is not performed.

In Japanese Patent Laid-Open No. 3-226237, maximum power tracking control is performed, but the switch 13
The electric water heater 12 is connected to the side a in the daytime, and the surplus of the generated power is supplied to the electric water heater 12 only when the surplus power of the solar cell 9 is generated. Is connected to the water heater 12 and the midnight power from the commercial AC power source 1 is supplied to the water heater 12, and the air conditioner 8 is also powered from the commercial AC power source 1. Therefore, the system is such that the electric water heater 12, which is a load other than the air conditioner 8, can be operated only when surplus power of the solar cell 9 is generated in the daytime.

An object of the present invention is to control the generated power of a solar cell as the optimum active power corresponding to the load, and supply the power to a plurality of home electric appliances via a power distribution unit that distributes the optimum active power. It is to provide a solar cell effective utilization system.

[0010]

The above-mentioned object is to connect a solar cell between a rectifier circuit for rectifying commercial power supplies of a plurality of home electric appliances and an inverter circuit, and Achieved by equipping the rectifier circuit with the optimal active power control device that controls the solar cell to always operate with the power that matches the load, and the power distribution unit that distributes the optimal active power to multiple home appliances. To be done.

[0011]

When the power generated by the solar cell is smaller than the total load of the plurality of home electric appliances, the power output of the solar cell is controlled to be maximum, and the power output of the solar cell is controlled by the plurality of home electric appliances. When the load is larger than the total load of the solar cells, the power generation output of the solar cell is reduced to be equal to the total load of the plurality of home electric appliances. In addition, the power distribution unit connects the generated power of the solar cell through the optimum active power control device, and is then connected to the rectifier circuits of multiple home appliances, giving priority to the home appliances in use and generating output of the solar cell. Supply. Alternatively, the power generation output of the solar cell is averaged and supplied regardless of the usage status of each home electric appliance. At this time, the power generation output of the solar cell is controlled to be maximum, and the plurality of home electric appliances are controlled to automatically operate through the power distribution unit.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
Will be described. 1 is a 50/60 Hz commercial power source, 9 is a solar cell, 14 is an optimum active power control device, 15 is a power distribution unit, 16 is an inverter room air conditioner, 17 is an inverter sanitary air conditioner, 18 is an inverter dehumidifying / drying unit, and 19 is an inverter. Shows a refrigerator, which is an electric home appliance that can control the system capacity by varying the compressor speed with an inverter. 20 is a rectifier circuit arranged inside the inverter room air conditioner, 21
Is a rectifier circuit disposed inside the inverter sanitary air conditioner 17, 22 is a rectifier circuit disposed inside the inverter dehumidifying / drying unit 18, and 23 is an inverter refrigerator 19
2 shows a rectifier circuit arranged inside the.

In the solar cell system having the above structure, the AC power of the commercial power supply 1 is the noise filter 27 built in the inverter room air conditioner 16, the inverter sanitary air conditioner 17, the inverter dehumidifying / drying unit 18, and the inverter refrigerator 19, respectively. Rectification circuits 20 to 23 through the power factor correction circuit 26 convert the DC power. The power factor correction circuit is installed according to the capacity of the home electric appliances. Further, the solar cell 9 outputs from the optimum active power control device 14 via the power distribution unit 15 to the inverter room air conditioner 16, the inverter sanitary air conditioner 17, the inverter dehumidifying / drying unit 18, and the rectifying circuits 20 to 23 in the inverter refrigerator 19. In parallel with this, electric power is supplied to the inverter room air conditioner 16, the inverter sanitary air conditioner 17, the inverter dehumidifying / drying unit 18, and the inverter refrigerator 19. The optimum active power control device 14 and the power distribution unit 15 are housed in an integrated unit. The inverter room air conditioner 16, the inverter sanitary air conditioner 17, the inverter dehumidifying / drying unit 18, and the inverter refrigerator 19 drive the compressor 25 via the inverter 24 with the power of the commercial power source 1 or the solar battery 9 to supply the respective home appliances. drive.

The electric power of the solar cell 9 has a constant current operating region and a constant voltage operating region as described in the prior art of FIG. 6, and the maximum current (current value in the constant current operating region) is determined according to the illuminance.
Has the property of changing. Therefore, the optimum active power control device 14 and the power distribution unit 15 are controlled according to the sum of the output power of the solar cell and the load of each home electric appliance depending on the amount of solar radiation. This will be described below with reference to FIGS. 4 and 5.

FIG. 4 shows a system diagram in which the optimum active power control device and each home electric appliance are paired. The optimum active power control device 14
The inverter room air conditioner 16, the inverter sanitary air conditioner 17, the inverter dehumidifying / drying unit 18, and the inverter refrigerator 19 are paired. The optimum active power control device 14 calculates the power value by multiplying the output voltage of the solar cell 9 and the detected value of the output current which differ depending on the amount of solar radiation. The power distribution unit 15 includes an inverter room air conditioner 16, an inverter sanitary air conditioner 17, an inverter dehumidifying / drying unit 18, and an inverter refrigerator 19.
Is detected as the load current and compared with the output current detected by the optimum active power control device 14. The output current of the solar cell 9 is the inverter room air conditioner 16, the inverter sanitary air conditioner 17, the inverter dehumidifying and drying unit 1.
8. If the load current is larger than the load current of each of the inverter refrigerator 19, the output current of the solar cell 9 is reduced to output each of the inverter room air conditioner 16, the inverter sanitary air conditioner 17, the inverter dehumidifying / drying unit 18, and the inverter refrigerator 19. The optimum active power controller 14 is controlled so that it becomes equivalent to the current. Further, when the output current of the solar cell 9 is smaller than the load current of each of the inverter room air conditioner 16, the inverter sanitary air conditioner 17, the inverter dehumidifying / drying unit 18, and the inverter refrigerator 19, the output of the solar cell 9 is maximized. In other words, the optimum active power control device 14 is controlled so that the value obtained by multiplying the output voltage of the solar cell 9 and the detected value of the output current is maximized. These controls are individually controlled for each home electric appliance. It should be noted that in this embodiment, the number of home electric appliances as loads is four, but the number of home electric appliances is not particularly limited.

FIG. 5 shows a diagram of a home electric appliance control system using a power distribution unit. As in FIG. 4, the optimum active power control device 14 calculates the power value by multiplying the detected values of the output voltage and the output current of the solar cell 9 that differ depending on the amount of solar radiation. The power distribution unit 15 detects the respective loads of the inverter room air conditioner 16, the inverter sanitary air conditioner 17, the inverter dehumidifying / drying unit 18, and the inverter refrigerator 19 as load currents by the power distributor 15 ′, calculates the sum, and obtains the optimum effectiveness. The output current detected by the power control device 14 is compared. When the output current of the solar cell 9 is larger than the sum of the load currents of the inverter room air conditioner 16, the inverter sanitary air conditioner 17, the inverter dehumidifying / drying unit 18, and the inverter refrigerator 19,
The optimum active power control device 14 is controlled so that the output current of the solar cell 9 is reduced to be equivalent to the total load current. When the output current of the solar cell 9 is smaller than the total load current, the output of the solar cell 9 is maximized, in other words, the output voltage of the solar cell 9 and the detected value of the output current are multiplied. The optimum active power control device 14 is controlled so that the value becomes maximum. In this embodiment as well, the number of home electric appliances as loads is four, but the number of home electric appliances is not particularly limited.

In the daytime when the output power of the solar cell 9 is generated, in order to effectively use the output power of the solar cell 9, not only the refrigerator which is always operating but also the room air conditioner is automatically operated. In this case, the power distribution unit 15 can preferentially distribute the output power of the solar cell 9.

The power source of the inverter sanitary air conditioner 17 and the inverter dehumidifying / drying unit 18 is the solar cell 9
It is also possible to control only by inputting and to connect to the commercial power source 1 so that the solar cell 9 operates only when surplus power is generated in the daytime.

[0019]

According to the present invention, a solar cell is used in combination with a commercial power source, and the output power of the solar cell is adjusted by an optimum active power control device according to the amount of solar radiation and the load, and the solar cell is operated independently. Mode, and a system that can drive DC-powered home appliances in the combined operation mode with the commercial power supply, and can supply solar cell output power to multiple DC-powered home appliances by the power distribution unit. It becomes possible to effectively utilize the photovoltaic power.

Further, since the surplus electric power is used, the electric power can be generously used for the sanitary air conditioning, the dehumidifying and drying unit, etc., so that the improvement of the quality of life can be promoted.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a solar cell.

FIG. 2 is a system diagram of a room air conditioner, a sanitary air conditioner, and a dehumidifying / drying unit system.

FIG. 3 is a system diagram of a refrigerator.

FIG. 4 is a system diagram of a pair of the optimum active power control device and each home electric appliance.

FIG. 5 is a control system diagram of a home electric appliance using a power distribution unit.

FIG. 6 is a basic circuit configuration diagram of a conventional solar cell room air conditioner.

FIG. 7 is a VI characteristic diagram of a solar cell.

FIG. 8 is a system diagram including a solar cell, an air conditioner, and an electric water heater according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Commercial power supply, 2 ... Air-conditioner drive part, 3 ... Rectifier circuit part, 4 ... Inverter part, 5 ... Solar battery, 6 ... Reverse current prevention diode, 7 ... DC / AC converter, 8 ... Room air conditioner, 9 ... Solar battery , 10 ... DC / AC inverter, 11 ... Maximum power tracking device, 12 ... Electric water heater, 13 ... Changeover switch, 14 ... Optimal active power control device, 15 ... Power distribution unit, 16 ... Room air conditioner, 17 ... Sanitary Air conditioner, 18 ... Dehumidifying / drying unit, 19 ... Refrigerator, 20-23 ... Rectifier circuit, 24 ... Inverter, 25 ... Compressor, 26 ... Power factor improving circuit, 27 ... Noise filter, 28 ... Power supply, 29 ... Control circuit, 30 ... indoor control circuit, 31 ... indoor / outdoor connection part, 32 ... indoor / outdoor connection part, 33 ... solar cell and outdoor unit connection part.

Claims (5)

[Claims] 1. A plurality of rectifier circuits for rectifying a commercial power supply,
In a plurality of inverter circuits connected to the output of the rectifier circuit and a plurality of home appliances that are driven by direct current by the output of the inverter circuit, between the plurality of rectifier circuits and the plurality of inverter circuits A solar cell system comprising: a solar cell that receives sunlight to generate an electromotive force; an optimum active power control device; and a power distribution unit that distributes the optimum active power to the plurality of home appliances. 2. The optimum active power control device according to claim 1, when the power output of the solar cell is smaller than the total load of the plurality of home electric appliances, the power output of the solar cell is maximized. When the power generation output of the solar cell is greater than the total load of the home electric appliances, the power generation output of the solar cell is reduced to the same level as the total load of the plurality of home electric appliances. And solar cell system. 3. The power distribution unit according to claim 1, wherein after the power generation output of the solar cell is connected through the optimum active power control device, the power distribution unit is connected to the rectifier circuits of the plurality of home electric appliances and is used. A solar cell system characterized by preferentially supplying power output of the solar cell to existing home appliances. 4. The power distribution unit according to claim 1, wherein the power distribution unit is connected to the rectifier circuits of the plurality of home electric appliances after connecting the power generation output of the solar cell through the optimum active power control device. What is claimed is: 1. A solar cell system characterized by averaging and supplying the power generation output of the solar cell regardless of the usage status of home appliances. 5. The power generation output of the solar cell according to claim 1 or 4, when the power generation output of the solar cell is greater than the total load of the plurality of home electric appliances, the power generation output of the solar cell is controlled to be maximum. A solar cell system, wherein the plurality of home electric appliances are automatically operated through the power distribution unit.