JPH08172209A - Solar cell power source and power supplying method using the power source - Google Patents

Abstract

PURPOSE: To efficiently supply power by suitably altering the supply source of the power by a changeover switch in response to high or low temperature time and the object to be supplied of the power. CONSTITUTION: A first solar cell circuit 10 has the numbers of series and parallel solar cells in which the upper limit set voltage 94 at the time of a high temperature becomes substantially at the maximum power point A. A second solar cell circuit 20 has the numbers of series and parallel solar cells in which the upper limit set voltage 94 at the time of a low temperature becomes substantially at the maximum power point B. That is, the circuit 20 for obtaining sufficient power at the time of the low temperature has smaller number of the series cells than that of the circuit 10. At the time of the high temperature, a changeover switch 60 is switched to connect to circuit 10 to a constant power load 30 and the circuit 20 to a constant resistance load 50. On the other hand, at the time of the low temperature, the switch 60 is switched to connect the circuit 10 to the load 50 and the circuit 20 to the load 30.

Description

Detailed Description of the Invention

[0001]

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

[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 becomes small, and when the cell temperature is low, the value of the maximum power point becomes large.

In the solar battery power supply device, the upper limit voltage (see FIG. 5) is limited in order to protect the equipment to which power is supplied, and the number of solar cells connected in series is such that this upper limit set voltage is for all solar cells. The number of cells was below 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.

To such a solar cell circuit 101, a constant power load 102 such as a DC / DC converter and a constant resistance load 103 such as a heater, which are the objects of power supply, are connected. The resistive load 103 was operated by the electric power supplied from the solar cell circuit 101.

Reference numeral 104 is 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, and prevents excessive voltage stress from being applied to the constant power load 102 and the constant resistance load 103. It was

That is, the solar cell has characteristics that the output voltage is low and the output current is large when the cell temperature is high, and the output voltage is high and the output current is small when the cell temperature is low. 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 is a blocking diode, and the blocking diode 105 prevents the reverse flow of current.

[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
Does not match, and constant power load 102 and constant resistance load 1
03 It was not possible to supply sufficient power for operating.

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, since the output voltage increases as the temperature of the solar battery cell decreases, if the output voltage of the solar battery circuit 101 at low temperature and the maximum power point C2 match, the maximum power in the curve 202 can be supplied. is there.

However, in the conventional solar cell power supply device,
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 solar cell groups arranged in parallel is increased, the solar cell circuit 101 becomes larger and the surplus 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 problems, and enables efficient power supply in the vicinity of the earth where the temperature is high and in deep space where the temperature is low, and the size and weight of the device can be reduced. An object of the present invention is to provide a solar cell power supply device that can be used and a power supply method using the solar cell power supply device.

[0022]

In order to achieve the above object, the solar battery power supply device of the present invention has a solar battery circuit composed of a large number of solar battery cells, and supplies power to a constant power load and a constant resistance load. In the solar battery power supply device for supplying, a first solar battery circuit, a second solar battery circuit having a smaller number of solar battery cells connected in series than the first solar battery circuit, and the first solar battery circuit at high temperature The maximum power setting point of the output characteristics of, and the upper limit set voltage that is less than the maximum power point of the output characteristics of the second solar cell circuit at low temperature is set, the constant power load at high temperature and low temperature The upper limit voltage control circuit for limiting the upper limit voltage to the upper limit set voltage, connection of the first solar cell circuit and constant power load, constant resistance load, and the second solar cell circuit and constant power load, constant resistance load Connection of Ri changing a configuration equipped with a selector switch.

Further, the power supply method of the present invention is a power supply method using the above-mentioned solar cell power supply device, wherein the changeover switch connects the first solar cell circuit and a constant power load at a high temperature. Together with the second solar cell circuit and the constant resistance load, to supply power to the constant power load and the constant resistance load, also, at low temperature, by the changeover switch, the first solar cell circuit and constant In this method, a resistance load is connected and a constant power load is connected to the second solar cell circuit to supply power to the constant power load and the constant resistance load.

[0024]

The operation of the above-described solar cell power supply device of the present invention and the power supply method using this solar cell power supply device 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.

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. As a result, 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 the operation of the heater and the like at high temperatures.

Next, the operation at a low temperature (low temperature environment) in deep space such as Mars will be described. By connecting the first solar cell circuit and the constant resistance load at a low temperature, 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. This reduces the temperature of the solar cells at low temperatures,
Even if the maximum power point of the first solar cell circuit increases,
Since the output voltage of the first solar cell circuit also becomes high, a large amount of power can be supplied to the constant resistance load.

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 the solar cell power supply device of the present invention and a power supply method using this solar cell power supply device will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a solar cell power supply device according to this 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 the solar cell power supply device of the present invention will be described. In FIG. 1, 10 and 20 are the first and second solar cell circuits, both of which are solar cell groups in which a plurality of solar cells are connected in series (not shown).
Are further 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 constructed so as to generate sufficient electric power at a low temperature as shown by a curve 92 in FIG. 3, and the upper limit set voltage 94 at the low temperature is almost the maximum electric power point. The number of solar battery cells connected in series and the number of parallel solar cells are set to B. That is, the second solar battery circuit 20 that tries to obtain sufficient power at a low temperature has a smaller number of solar battery cells in series than the first solar battery 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 electric power supplied from 0, 20 into a 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 the upper limit setting 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 changeover control of the changeover switch 60 is 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 pieces of information are constantly transmitted to the ground station by the telemetry signal from the spacecraft, the ground station makes a judgment based on these pieces of information, and the changeover switch 60 is switched 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 electric power (intersection point between the curve 91 and the upper limit set voltage 94 in FIG. 2) that is not sufficient and surplus power at the maximum power point A1.

By connecting the second solar cell circuit 20 and the constant resistance load 50 at high temperature, the curve 92 of 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. As a result, even if the maximum power point A of the first solar cell circuit increases due to the temperature drop of the solar cell at low temperature, the output voltage of the first solar cell circuit 10 also increases, so that the maximum power point A2 is almost reached. Sufficient electric power (the intersection of the curve 91 and the curve 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.

According to the above-mentioned solar cell power supply device of this embodiment and the power supply method using this solar cell power supply device,
A solar cell circuit that is a power supply source is formed by a first solar cell circuit 10 for high temperature and a second solar cell circuit 20 for low temperature in which the number of series of solar cells is small, and at the time of high temperature and low temperature The temperature is high because the power supply source (first and second solar cell circuits 10 and 20) is appropriately changed according to the power supply target (constant power load 30 and constant resistance load 50). Electric power can be efficiently supplied around the earth and in deep space where the temperature is low.

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. Further, according to the solar cell power supply device and its power supply method of the present embodiment, surplus power is not generated at high temperature and low temperature, so that the power processing capacity of the upper limit voltage limiting circuit 40 can be reduced. Therefore, it is possible to reduce the size and weight of the upper limit voltage limiting circuit 40.

The solar cell power supply device of the present invention and the power supply method using this solar cell power supply device are not limited to the above embodiments.

In the above embodiment, the case where the present invention is applied to a spacecraft for exploring deep space such as Mars has been described. However, the present invention is not particularly limited, and the temperature of the solar battery cell greatly changes. If it is applied to a spacecraft that operates in such a space environment, the same effect as that of 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 solar cell power supply device of the present invention, it is possible to efficiently supply electric power in the surroundings of the earth where the temperature is high and in deep space where the temperature is low. The reduction in the number of solar cells and the reduction in the power processing capacity of the upper limit voltage limiting circuit can reduce the size and weight of the device.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a solar cell power supply device according to an embodiment of 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 (2)

[Claims] 1. A solar cell power supply device having a solar cell circuit composed of a large number of solar cells and supplying electric power to a constant power load and a constant resistance load, a first solar cell circuit and the first solar cell circuit. And a second solar cell circuit having a small number of solar cells connected in series, and the second solar cell at a temperature lower than or equal to the power maximum point of the output characteristics of the first solar cell circuit at high temperature. An upper limit set voltage that is equal to or lower than the maximum power point of the output characteristics of the battery circuit is set, and an upper limit voltage control circuit that limits the upper limit voltage of the constant power load at high temperature and low temperature to the upper limit set voltage, A solar cell power supply device comprising: a connection between a solar cell circuit and a constant power load and a constant resistance load; and a changeover switch for switching between the second solar cell circuit and a constant power load and a constant resistance load. 2. At high temperature, the changeover switch connects the first solar cell circuit and a constant power load, and connects the second solar cell circuit and a constant resistance load,
Power is supplied to the constant power load and the constant resistance load, and at the time of low temperature, the changeover switch connects the first solar cell circuit and the constant resistance load, and the second solar cell circuit and the constant power load. The power supply method using the solar cell power supply device according to claim 1, wherein the solar cell power supply device is connected to supply power to the constant power load and the constant resistance load.