JP2666754B2 - Power supply method in solar cell power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply method in a solar cell power supply for supplying electric power to a spacecraft such as an artificial satellite, and more particularly, to a power supply method in a space environment where the temperature of a solar cell greatly changes. The present invention relates to a power supply method for a solar cell power supply device capable of efficiently supplying the power.

[0002]

2. Description of the Related Art Some space vehicles such as artificial satellites are intended for deep space exploration of Mars or the like. As a power source for such a space vehicle, a solar cell power supply having a plurality of solar cells is used. The device was used. Hereinafter, a conventional solar cell power supply device mounted on a spacecraft for deep space exploration will be described with reference to FIG. FIG. 4 is a circuit diagram showing a conventional solar cell power supply device.

In FIG. 1, reference numeral 101 denotes a solar cell circuit, which has a configuration in which a plurality of solar cell groups (not shown) in which a plurality of solar cells are connected in series with each other are further connected in parallel.

Here, the maximum point of the power of one solar cell (the voltage value at which the maximum power is obtained) depends on the temperature of the solar cell if the sunlight intensity is constant. That is, when the cell temperature is high, the value of the maximum power point decreases, and when the cell temperature is low, the value of the maximum power point increases.

In a solar cell power supply, the upper limit voltage (see FIG. 5) is limited in order to protect the equipment to be supplied with power. The number was set to be equal to or less than the maximum power point of the cell. Therefore, from the temperature characteristics of the solar cell,
Where the cell temperature was high, the number of cell series had to be increased, and conversely, where the cell temperature was low, the number of cell series could be reduced.

In the conventional solar cell circuit 101, the number of series cells is set in a high temperature environment near the earth.

[0007] The number of the solar cells in parallel has been determined by the relationship between the connected load and the required amount of power.

A constant power load 102 such as a DC / DC converter and a constant resistance load 103 such as a heater to which power is supplied are connected to such a solar cell circuit 101. The resistance load 103 was operated by the electric power supplied from the solar cell circuit 101.

Reference numeral 104 denotes an upper limit voltage limiting circuit.
The power consuming unit includes a transistor and a resistor (not shown) and a control unit that drives the transistor of the power consuming unit.

The upper limit voltage limiting circuit 104 limits the output voltage from the solar cell circuit 101 to the upper limit set voltage to prevent the constant power load 102 and the constant resistance load 103 from being applied with excessive voltage stress. Was.

That is, the solar battery cell has a characteristic that when the cell temperature increases, the output voltage decreases and the output current increases, and when the cell temperature decreases, the output voltage increases and the output current decreases. When the output voltage of the solar cell circuit 101 rises above the upper limit set voltage due to a change in sunlight intensity or the like, the control unit detects this,
By driving the transistor to cause the power consuming unit to consume a predetermined current, the output voltage is limited to an upper limit set voltage.

Reference numeral 105 denotes a blocking diode, and the blocking diode 105 prevents current from flowing backward.

[0013]

However, in the above-described conventional solar battery power supply device, the number of series solar battery cells and the upper limit set voltage are determined in a high temperature environment near the earth. , Constant resistance load 103 such as heater
However, there is a problem that sufficient power cannot be supplied in a low-temperature deep space where the power consumption increases.

Near the earth, the intensity of sunlight is high because it is close to the sun, and the output characteristics of the solar cell circuit 101 are as shown by a curve 201 in FIG. And the conventional solar cell power supply device has the maximum power point C of the output characteristic of the curve 201.
Since 1 was set to be equal to or less than the upper limit set voltage 203, the number of cells in series is sufficient power near the earth to operate the constant power load 102 and the constant resistance load 103 (FIG. 5).
(The intersection of the curve 201 and the upper limit setting voltage 203).

However, in deep space such as Mars, the sunlight intensity is low, so that the output characteristic of the solar cell circuit 101 changes as shown by a curve 202 in FIG. 5, and the upper limit set based on the output characteristic at high temperature Voltage 203 and maximum power point C2
Do not match, the constant power load 102 and the constant resistance load 1
03 could not supply enough power to operate.

That is, in the low temperature deep space, the curve 202
As shown in (2), the temperature of the solar battery cell becomes low, and the value of the maximum power point greatly changes from C1 to C2. Here, if the temperature of the solar battery cell decreases, the output voltage also increases. Therefore, if the output voltage of the solar battery circuit 101 at a low temperature matches the maximum power point C2, the maximum power in the curve 202 can be supplied. is there.

However, in the conventional solar cell power supply,
The number of solar cells connected in series is set to the number that places importance on the high-temperature environment near the earth, and the upper limit setting voltage 203 according to the high-temperature environment has been set. Is restricted (Fig. 5
At the intersection of the curve 202 and the upper limit setting voltage 203), sufficient power could not be obtained.

In order to solve such a problem, in the above-described conventional solar cell power supply, sufficient power is obtained in deep space by increasing the number of parallel-connected solar cell groups. However, when the number of parallel solar cell groups is increased, the size of the solar cell circuit 101 increases, and excess power becomes excessive near the earth where the power consumption of the constant resistance load 103 such as a heater decreases. There was a problem.

When the surplus power near the earth becomes excessive, it is necessary to increase the power processing capacity of the upper limit voltage limiting circuit 105, and therefore, the transistors and resistors forming the power consuming portion must be increased in capacity. This also causes a problem that the upper limit voltage limiting circuit 103 becomes large.

As described above, in the above-described conventional solar cell power supply, excessive power is generated in the vicinity of the earth where the power consumption of the heater and the like is reduced, while the power consumption of the heater and the like on Mars is increased. There has been a problem that sufficient power cannot be supplied in deep space, and efficient power supply cannot be performed.

The present invention has been made in view of the above-mentioned problems, and enables efficient power supply in the vicinity of the high temperature earth and in the deep space where the temperature is low, and at the same time, to reduce the size and weight of the apparatus. All the solar cell power supply that can be
The purpose of the present invention is to provide an electric power supply method.

[0022]

In order to achieve the above object, a solar cell power supply according to the present invention generates a large amount of electric power at a high temperature.
A first solar cell circuit to live, and <br/> second photovoltaic cell circuit for generating a high power at a low temperature, equal to or less than the maximum power point of the output characteristic of the first photovoltaic cell circuit at high temperature, and, An upper limit voltage that is equal to or lower than the power maximum point of the output characteristics of the second solar cell circuit at a low temperature is set, and an upper voltage limit of the constant power load at a high temperature and a low temperature is limited to the upper limit voltage. A solar cell power supply device comprising: a control circuit; and a changeover switch that switches connection between the first solar cell circuit and a constant power load or a constant resistance load, and connection between a second solar cell circuit and a constant power load or a constant resistance load. At high
At the time of warming, the changeover switch causes the first solar cell circuit to rotate.
Connecting the road and the constant power load,
The circuit and the constant resistance load are connected, and the constant power load and the constant resistance are connected.
Power is supplied to the load, and when the temperature is low, the switch
To connect the first solar cell circuit to a constant resistance load.
And the constant power load is connected to the second solar cell circuit.
To supply power to the constant power load and the constant resistance load
There is as a law.

[0023]

The operation of the power supply method in the above-described solar cell power supply of the present invention will be described.

First, when the temperature is high near the earth (high temperature environment)
The operation in is described. At a high temperature, by connecting the first solar cell circuit and a constant power load, the output voltage from the first solar cell circuit is limited to an upper limit set voltage by an upper limit voltage limiting circuit, and the constant power from the first solar cell circuit is set. Power is supplied to the load at a power maximum point that is sufficient and does not become surplus power.

Further, by connecting the second solar cell circuit and the constant resistance load at a high temperature, the output voltage from the second solar cell circuit is not limited to the upper limit set voltage by the upper limit voltage limiting circuit. Thus, there is no power supply at the maximum power point of the second solar cell circuit, and sufficient power is supplied from the second solar cell circuit to the constant resistance load for operation of the heater and the like at high temperatures.

Next, the operation at low temperature (low temperature environment) in deep space such as Mars will be described. At a low temperature, by connecting the first solar cell circuit and the constant resistance load, the output voltage from the first solar cell circuit is not limited to the upper limit set voltage by the upper limit voltage limiting circuit.

With this, even if the maximum power point of the first solar cell circuit increases due to a decrease in the temperature of the solar cell at a low temperature, the output voltage of the first solar cell circuit also increases. Large power can be supplied.

Further, at a low temperature, by connecting the second solar cell circuit to a constant power load, the output voltage from the second solar cell circuit is limited to an upper limit set voltage by the upper limit voltage limiting circuit. The electric power at the maximum electric power point is supplied from the two solar cell circuits to the constant electric power load, which is sufficient and does not become surplus electric power.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a power supply method in a solar cell power supply according to the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a solar cell power supply used in the method of the present embodiment. FIG. 2 is a graph showing the output characteristics of the first and second solar cell circuits used in the solar cell power supply device at high temperatures, and FIG. 3 is the output of the first and second solar cell circuits at low temperatures. It is a graph which shows a characteristic.

First, an embodiment of this solar cell power supply will be described. In FIG. 1, reference numerals 10 and 20 denote first and second solar cell circuits, each of which is a group of solar cells (not shown) in which a plurality of solar cells are connected in series with each other.
Further, the configuration is such that a plurality are connected in parallel.

However, as shown by a curve 91 in FIG. 2, the first solar cell circuit 10 is configured to generate sufficient power at high temperatures, and the upper limit set voltage 94 at high temperatures is substantially equal to the maximum power point. A is the number of solar cells connected in series and the number of parallel solar cells.

The second solar cell circuit 20 is configured to generate sufficient power at low temperatures, as shown by a curve 92 in FIG. 3, and the upper limit set voltage 94 at low temperatures is substantially equal to the maximum power point. B is the number of solar cells in series and the number of parallel solar cells. That is, the second solar cell circuit 20 that seeks to obtain sufficient power at low temperatures has a smaller number of solar cells connected in series than the first solar cell circuit 10.

In FIG. 1, reference numeral 30 denotes a constant power load such as a DC / DC converter or the like.
It operates by converting the power supplied from 0 and 20 into voltage. Such a constant power load 30 receives stress due to a rise in voltage caused by a change in the temperature of the photovoltaic cells. Therefore, the upper limit voltage limiting circuit 40 is connected to the constant power load 30.

The upper limit voltage circuit 40 is composed of a power consuming unit including a transistor and a resistor (not shown) and a control unit for driving the transistor of the power consuming unit. The control unit supplies the output characteristic of the first solar cell circuit 10 at the time of high temperature (curve 91 in FIG. 2) to the power maximum point A1 and the output of the second solar cell circuit 20 at the time of low temperature. An upper limit set voltage 94 which is almost the maximum power point B2 of the characteristic (curve 92 in FIG. 3) is set.

The upper-limit voltage circuit 40 operates at first and second solar cell circuits 10, 2 at high and low temperatures.
The voltage applied to the constant power load 30 from 0 is set to the upper limit set voltage 94
To prevent excessive voltage stress from being applied to the constant power load 30.

Reference numeral 50 denotes a constant resistance load such as a heater, which does not receive a voltage stress. Therefore, the upper limit voltage circuit 40 does not limit the upper limit voltage.

Reference numeral 60 denotes a changeover switch for connecting the first solar cell circuit 10 to the constant power load 30 and the constant resistance load 50, and connecting the second solar cell circuit 20 to the constant power load 30 and the constant resistance load 50. Switch.

The switching of the changeover switch 60 is controlled as follows.
Information such as the temperature of the photovoltaic cells, the sunlight intensity, the temperature of each part of the spacecraft (the amount of use of the heater), and the use status of other loads is comprehensively determined. That is, since these information are always transmitted to the ground station by the telemetry signal from the spacecraft, the ground station determines based on the information and switches the changeover switch 60 by a command from the ground station.

Blocking diodes 70 and 80 prevent the current from flowing back to the first and second solar cell circuits 10 and 20 by the blocking diodes 70 and 80.

Next, an embodiment of a power supply method using the above-described solar cell power supply device will be described with reference to FIGS.

When the temperature is high near the earth or the like, as shown in FIG. 1, the changeover switch 60 is switched to connect the first solar cell circuit 10 to the constant power load 30 and to connect the second solar cell circuit 20 A constant resistance load 50 is connected.

When the first solar cell circuit 10 and the constant power load 30 are connected at a high temperature, the output voltage from the first solar cell circuit 10 is increased by the upper limit voltage limiting circuit 40 as shown by a curve 91 in FIG. Limited to the upper limit setting voltage 94,
The first solar cell circuit 10 supplies the constant power load 30 with power that is sufficient and does not become excess power at the power maximum point A1 (the intersection of the curve 91 and the upper limit set voltage 94 in FIG. 2).

At the time of high temperature, by connecting the second solar cell circuit 20 and the constant resistance load 50, the curve 92 in FIG.
As shown in (2), the output voltage from the second solar cell circuit 20 is no longer limited by the upper limit voltage limit circuit 40 to the upper limit set voltage 94. As a result, there is no power supply at the maximum power point B1 of the second solar cell circuit 20, and the second solar cell circuit 20 supplies the constant resistance load 50 with electric power sufficient for operation of a heater or the like at high temperatures (see FIG. 2). Curves 92 and 9
3 intersections) are supplied.

On the other hand, when the temperature is low in deep space such as Mars, as shown in FIG. 1, the changeover switch 60 is switched to connect the first solar cell circuit 10 to the constant resistance load 50 and to connect the second solar cell The circuit 20 and the constant power load 30 are connected.

At a low temperature, by connecting the first solar cell circuit 10 and the constant resistance load 50, the output voltage from the first solar cell circuit 10 is controlled by the upper limit voltage limiting circuit 40 as shown by a curve 91 in FIG. It is no longer limited to the upper limit set voltage 94. Thus, even when the maximum power point A of the first solar cell circuit increases due to the temperature decrease of the solar cell at a low temperature, the output voltage of the first solar cell circuit 10 also increases. Sufficient power (the intersection of the curves 91 and 93 in FIG. 3) can be supplied to the constant resistance load 40.

Further, by connecting the second solar cell circuit 20 and the constant power load 30 at a low temperature, a curve 92 in FIG.
As shown in (2), the output voltage from the second solar cell circuit 20 is limited to the upper limit set voltage 94 by the upper limit voltage limiting circuit 40, and the power that does not become sufficient and surplus power at the power maximum point B2 (the curve 92 in FIG. (Intersection of the upper limit set voltage 94) can be supplied to the constant power load 30.

[0047] All the solar cell power supply device of the present embodiment described above
According to the power supply method, a solar cell circuit as a power supply source is formed of the first solar cell circuit 10 for high temperature and the second solar cell circuit 20 for low temperature having a small number of solar cells in series. A method of appropriately changing the power supply source (first and second solar cell circuits 10 and 20) according to the configuration and the high and low temperatures and the power supply target (constant power load 30 and constant resistance load 50) As a result, power can be efficiently supplied around the earth with a high temperature and in the deep space with a low temperature.

In addition, the number of solar cells can be reduced by providing the second solar cell circuit 20 with the number of solar cells connected in series at the time of low temperature, and the size and weight of the entire solar cell circuit can be reduced. it can. Furthermore, according to the power supply method in the solar cell power supply device of the present embodiment, no surplus power is generated at both high and low temperatures, so that the power processing capacity of the upper limit voltage limiting circuit 40 can be reduced, and The size and weight of the upper limit voltage limiting circuit 40 can be reduced.

The power supply method in the solar cell power supply of the present invention is not limited to the above embodiment.

In the above embodiment, the case where the present invention is applied to a space vehicle for exploring deep space such as Mars has been described. If the present invention is applied to a spacecraft operating in such a space environment, the same effects as in the above embodiment can be obtained. For example, the present invention can be applied to an earth orbiting satellite having a large temperature difference between the sunshine and the shadow of the earth.

[0051]

As described above, according to the power supply method for the solar cell power supply of the present invention, the power supply apparatus is small and light.
The large amount of equipment enables efficient power supply around the hot Earth and deep space where the temperature is low .

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an example of a solar cell power supply device used in the present invention.

FIG. 2 is a graph showing output characteristics at a high temperature of first and second solar cell circuits used in the solar cell power supply device.

FIG. 3 is a graph showing output characteristics at a low temperature of the first and second solar cell circuits.

FIG. 4 is a circuit diagram showing a conventional solar cell power supply device.

FIG. 5 is a graph showing output characteristics at high and low temperatures of a solar cell circuit used in a conventional solar cell power supply device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 First solar cell circuit 20 Second solar cell circuit 30 Constant power load 40 Upper limit voltage limiting circuit 50 Constant resistance load 60 Changeover switch 70, 80 Blocking diode 94 Upper limit set voltage

Claims (1)

(57) [Claims] And 1. A first solar cell circuit to generate a high power at high temperature, and a second photovoltaic cell circuit for generating a high power at low temperatures, less power maximum point of the output characteristic of the first photovoltaic cell circuit at high temperature An upper limit setting voltage that is equal to or lower than a power maximum point of the output characteristic of the second solar cell circuit at a low temperature is set, and an upper limit voltage of the constant power load at a high temperature and a low temperature is set to the upper limit. An upper-limit voltage control circuit that limits the voltage, a connection switch that switches between the connection of the first solar cell circuit and the constant power load, the connection of the constant resistance load, and a connection switch of the second solar cell circuit and the connection of the constant power load and the constant resistance load. Equipped solar cell power
In the power supply device, at the time of high temperature, the first solar cell
Circuit and a constant power load, and
Connect a constant voltage load and a constant resistance load to
The load is supplied to the anti-load, and at the time of low temperature, the first switch is operated by the changeover switch.
Connect the positive cell circuit and the constant resistance load, and
Connecting the solar cell circuit and the constant power load,
And a constant-resistance load
Power supply method in the pond power supply.