JPS5942891B2 - solar power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention consists of a solar cell array in which a large number of small-output solar cell elements are electrically connected in series and parallel in order to obtain a large output, and a secondary battery that stores the output of the solar cell array. The present invention relates to a solar cell power supply device having a battery, and particularly to a method for controlling the power generated by the solar cell array.

The output control method of the solar cell array in a conventional solar cell power supply device has generally been based on a shunt circuit type control system as shown in FIG.

The circuit shown in FIG. 1 consists of a solar cell array 2 formed by electrically connecting a large number of solar cell elements 1 in series and parallel, a load 6 that consumes the power generated by the solar cell array 2, and a load 6. When a larger output than the output of the solar cell array 2 is required or when there is no output from the solar cell array 2, the storage battery 5 as a secondary battery supplies power to the load 6 and the surplus power of the solar cell array 2 is consumed. The output of the shunt circuit 3 and the solar cell array 2 is supplied to the load 6, the storage battery 5 is charged, the shunt circuit 3 is made to consume surplus power, and the power of the storage battery 5 is supplied to the load 6. It is composed of a power controller 4. In other words, this conventional method does not control the power itself generated by the solar cell array 2, but processes the power that has already been generated, so the current IL consumed by the load 6 and the power required by the storage battery 5 are Current IBAT
If the sum of (IL+IBAT) is less than the output current Isc generated in the solar cell array 2, that is, 1sc>
If the relationship is 1L+IBAT, ISC-(IL+
There will be a surplus current of IBAT)=15HUNT.

To explain this relationship from the V-I characteristic of the solar cell array, the VI characteristic T in FIG. 2 is the output characteristic of the solar cell array 2 in FIG. 1. VBUS in FIG. 2 is the operating voltage, and the intersection D between VBUS and the VI characteristic T is the solar cell array 2.
The output (power) is , and the intersection a of the straight line 10 and the current axis is the output current generated at that time. Therefore, 1s
When the relationship is UT since c>1L+, the load current L is from point A to the intersection B of straight line 8 and VBUS, and the current IBAT for charging the storage battery is from the intersection C of straight line 9 and VBUS to B. For example, the difference between intersections D and C is the surplus current SH
Therefore, it becomes UNT. That is, this ISHUNT
Since the current is passed through the shunt circuit 3 in Figure 1 and consumed by the power type resistor R with a large wattage that makes up the shunt circuit, most of the I2R power is consumed in the shunt circuit because the I2R power is consumed. It will be converted into heat. As an example, when this method is used in a satellite, heat generated from the shunt circuit will accumulate inside the satellite, raising the temperature of the entire satellite and causing the tolerance of the subsystems installed in the satellite to increase. If the satellite temperature rose above the normal temperature, it could cause subsystem failure.

In addition, regarding the resistance of the shunt circuit, it is necessary to consider delay and redundancy from the viewpoint of reliability. The dimensions are quite large, creating major constraints on satellite implementation.
There were drawbacks such as the need to consider the heat generated by the shunt circuit in the thermal design of the satellite. In order to solve these drawbacks, the present invention controls the power itself generated by the solar cell array, and only controls the output current of the sum of the current 1L required for the load and the current BAT required for the storage battery (IBAT+IL). This configuration controls the output of the solar cell array so as to prevent surplus power from being generated.

The drawings will be explained in detail below. FIG. 3 shows an embodiment of the present invention, in which 4'' supplies the output of the solar cell array 2 to the load 6 or the storage battery 5, or the output of the storage battery 5 to the load 6, and at the same time detects surplus power and A power controller 11 sends out a control signal necessary to reduce the output of the solar cell array 2 by the amount of surplus power, and a control signal from the power controller 4'' is used to irradiate the solar cell elements 1 of the solar cell array 2. The control unit is configured to move a shielding plate (not shown) that shields the light that enters the screen.

Next, the operation of this embodiment will be explained.

First, when the output current 1sc of the solar cell array 2 is larger than the sum of the current 1L of the load 6 and the charging current 1BAT to the storage battery, that is, Isc>IL+I3AT, the amount of surplus current of I8C-(IL+IBAT) in the power controller 4'' is detected, and the output current of the solar cell array 2 is increased for 1 s by the amount of the surplus current.
Decrease c itself, i.e. 180-IL+IBAT
The power controller 4'' sends out a control signal necessary to achieve this.The control signal activates the control unit 11, and the power is applied to only a portion of the solar cell elements 1 of the solar cell array 2. The shield plate blocks the incident light, thereby controlling the generated output current 1sc of the entire solar cell array 2 to be I8C - IL + IBAT.This is because the solar cell elements are blocked from the incident light. V-1 characteristics (voltage-current characteristics) of solar cell elements to receive shadows
This takes advantage of the phenomenon in which the object itself changes. Generally, in a solar cell array, a large number of solar cell elements 1 are electrically connected in parallel or in series so as to obtain a necessary output.

The parallel direction increases the amount of current, and the series direction increases the voltage.As an example, a solar cell array used in an artificial satellite has 2×2 cr! When using Si (silicon) solar cell elements of size i, a solar cell array is created by connecting approximately 60 solar cell elements in series and approximately 3 solar cell elements in parallel, and these solar cell arrays are further combined in parallel. do. FIG. 4, FIG. 5, and FIG. 6 show a portion of a solar cell array having 60 solar cells in series and 3 solar cells in parallel. Figure 4 shows a state in which one solar cell element of the solar cell array is not exposed to light (a state in which it is shaded), and similarly, Figure 5 shows a state in which two solar cell elements in a parallel direction are exposed to light. FIG. 6 shows a state in which all (three) solar cell elements in the parallel direction are not exposed to light (shaded state). FIG. 7 shows the results of an experiment to determine what the V-1 characteristics of the entire solar cell array would be under these three types of shadow conditions. In other words, the V-1 characteristic that is not shaded at all becomes curve 7, but when it is shaded in Fig. 4 it becomes curve 12, and when it is shaded in Fig. 5 it becomes curve 12. 13, when it is affected by the shadow of FIG. 6, it changes greatly as shown by curve 14. Now, if the operating voltage of the solar cell array is VBO8, it is 60 x 3-180.
By simply blocking the light incident on only 1 to 3 of the solar cell elements in the parallel direction, the operating point of the solar cell array changes from point H to point G-+F-+E, resulting in output. It can be seen that the current can be controlled until it becomes almost O. At this time,
The operating point of the solar cell array can be continuously changed from H to E by continuously changing the area of the surface of the element that shields the light incident on the solar cell element, rather than for each element. Next, examples of the present invention will be described.

An example of the control section 11 shown in FIG. 3 will be explained with reference to FIG. 8. FIG. 8 shows a device which mechanically creates shadows, and which creates shadows in the parallel direction in a solar cell array in which a large number of solar cell elements 1 are combined in series and in parallel. This consists of a servo motor 15, a gear 16 that transmits the force of the servo motor to the drum 18,
1r, a drum 18, a thin metal plate 19 for shielding light, a metal fitting 20 for holding the metal plate 19, and a metal fitting 21 for guiding the metal plate. When the output generated by the solar cell array is large, an electric signal proportional to the surplus power is sent from the power controller to rotate the servo motor 15. The rotational energy is transmitted through gears 16 and 17 to a drum 18 wrapped with a thin metal plate 19 that blocks light.
is transmitted, causing the drum 18 to rotate counterclockwise.
As a result, the thin light-shielding metal plate 19 extends along the guideline 21 in the parallel direction of the solar cell arrays, increasing the shadow area. Conversely, to eliminate the shadow, the servo motor 15 should be rotated in the opposite direction. Next, the power controller will be explained with reference to FIGS. 9 and 10. In addition, in FIG. 9, the part excluding the shunt circuit 3 and storage battery 5 is the conventional power controller 4 of FIG. 1, and in FIG. 10, the part excluding the storage battery 5 is the power controller of the present invention shown in FIG. The controller is 4″. First,
Referring to FIG. 9, the generated output of the solar cell array is transmitted to the storage battery 5 through the contact r1 of the relay R1 of the power controller.
and then to the load. Generally, the load and the solar cell array output fluctuate, so the remaining power after subtracting the load power from the array output flows to the storage battery 5. However, even large amounts of power can be applied to the storage battery until it is 100% charged, but if you continue to charge the storage battery 5 even after it is 100% charged, the storage battery temperature will rise suddenly and the storage battery voltage will continue to rise, and eventually the storage battery 5 will A short circuit may occur or the internal pressure may rise, resulting in a puncture. Therefore, a voltage comparison circuit 41 compares it with a constant voltage standard, a temperature comparison circuit 42 compares it with a constant temperature standard, and if the voltage or temperature of the storage battery 5 exceeds the standard, it is detected by an OR circuit 43 and relayed. R1 is operated to close its contact r1. This allows charging to occur via the low resistance r. At this time, the charging current is set to about C/50 (C is battery capacity). In addition, 44
is a temperature sensor. Then, a voltage proportional to the increase in storage battery voltage is applied to the base of the transistor Tr of the shunt circuit 3 to control the current flowing through the resistor R of the shunt circuit 3. In this way, the surplus output of the solar cell array is consumed by the shunt circuit 3. Note that when there is no output from the solar cell array, power from the storage battery flows to the load via diode D (if relay contact rl is closed, current flows to the load via the relay contact).
. The power controller 4'' used in the present invention shown in FIG. 10 is also basically the same as the conventional power controller 4 shown in FIG.

The only difference is that in order to prevent the voltage of the storage battery 5 from rising above the reference level, a buffer circuit 45 is required for supplying an electrical signal exceeding a certain reference value from the voltage comparison circuit 41 to the control unit 11 shown in FIG. 3. . This buffer circuit 45 converts it into an electrical signal suitable for operating the control section. As explained above, the solar cell power supply device of the present invention has a configuration that controls the generated output itself of a solar cell array formed by connecting a large number of solar cell elements in series and parallel, so it is similar to conventional devices. Shunt circuits that consume excess power are no longer required,
It is also possible to prevent temperature rise due to heat generation in the shunt circuit.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional solar battery power supply device, Fig. 2 is a V-1 characteristic diagram of Fig. 1, Fig. 3 is a block diagram of an embodiment of the present invention, Figs. Figure 6 is a diagram for explaining the operating principle of Figure 3, and Figure 7 is V-1 of Figure 3.
A characteristic diagram, FIG. 8 is a perspective view showing an example of the control unit 11 in FIG. 3, and FIG. 9 is an example of a portion including the power controller 4, storage battery 5, and shunt circuit 3 shown in FIG. Circuit diagram, 10th
The figure is a circuit diagram showing an example of a portion including the power controller 4'' and the storage battery 5 in Fig. 3. In the figure, 1: solar cell element, 2: solar cell array, 3: shunt circuit. , 4 and 4″: power controller, 5
: storage battery, 6: load, 7: V-1 characteristic of solar panel, 11: control unit.

Claims (1)

[Claims] 1 A solar cell array comprising a large number of solar cell elements electrically connected in series and parallel, a secondary battery that stores the output of the solar cell array, and a light shielding plate that blocks incident light from the solar cell array. a control unit for controlling the output of the solar cell array, the light shielding plate being configured to move according to an input signal; and a power controller configured to detect surplus power and provide the control section with a control signal necessary to reduce the output of the solar cell array by the surplus power.