JPS6316764B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a solar cell power supply device that can control surplus current of a solar cell array.

<Conventional Example> As a conventional solar cell power supply device, one shown in the configuration diagram of FIG. 1 has been used. In the figure, 1 is a solar cell element that converts light energy into electrical energy;
2 is a solar cell array in which a plurality of solar cell elements 1 are electrically connected in series and parallel to obtain a predetermined power; 3;
4 is a load that consumes the power generated by the solar cell array 2, and 4 is a load that supplies and adjusts power to the load when the load power becomes larger than the power generated by the solar cell array or when the power generated by the solar cell array decreases. A storage battery 5 has a power storage function, and 5 is a power controller that balances and controls surplus power and power shortage that occur between the power generated by the solar cell array and the load power. When the power generated by the solar cell array 2 is insufficient, this power controller 5 controls the output of the storage battery 4 so that the insufficient power is supplied from the storage battery 4 to the load 2. When there is surplus power, the required amount of power is transferred to the storage battery. The shunt circuit 6 has the functions of a charge/discharge control circuit that performs input control to charge the battery 4 and a current control circuit that controls the input current using the shunt circuit 6. Reference numeral 6 denotes a shunt circuit that has a function of consuming the surplus power when there is still surplus power generated by the solar cell array even after power is supplied to the load and the storage battery is charged.

This device does not control the power itself generated by the solar cell array 2, but rather deals with the power that has already been generated. Here, if the power generated by the solar cell array 2 is I _SC , the current consumed by the load 3 is I _L , and the current charged to the storage battery 4 is I _BAT , if I _SC becomes smaller than ( _IL + I _BAT ), then The shunt current I _SHNT consumed by the shunt circuit 6 is as follows.

I _SHNT = I _SC - ( _IL + I _BAT ) Fig. 2 is a voltage-current (V-I) characteristic diagram of a solar cell, and shows the V-I characteristic line 7 representing the output of the solar cell array. V _BUS is the operating voltage of this circuit,
Let E be the intersection of V _BUS and VI characteristic line 7. Point E
Let A be the point translated to the current axis, H be the point E translated parallel to the voltage axis, and D be the zero point.The area surrounded by points A, D, H, and E represents the operation of the solar cell array. This is the generated power at the voltage V _BUS , and point A indicates the generated current. Here, the current point consumed by the load is C, and the charging current to the storage battery is B-
C, A-B becomes a shunt current, and points A,
The portion surrounded by B, F, and E becomes shunt power. This shunt circuit generally uses a power type resistor with a resistance value R, and the power of I ² _SHNT ×R is consumed as heat in the shunt circuit.

<Problems to be solved> When this device is adopted in a satellite, the amount generated from the shunt circuit will gradually accumulate inside the satellite due to the generation of surplus current, causing the temperature of the entire satellite to rise, causing the temperature of the entire satellite to rise. It is also possible that the temperature exceeds the allowable temperature of each device, causing malfunction or fatal failure. In addition, when performing satellite thermal design by predicting the amount of heat generated from the shunt circuit, it is important to note that the amount of current generated by the solar cell array varies due to differences in the amount of load current depending on the satellite's operation mode, and differences in the amount of sunlight incident. Thermal design becomes extremely difficult because the amount of excess current is not constant. Moreover, when designing a shunt circuit, it is necessary to have the ability to consume all the power generated by the solar cell array, taking into consideration the times when the load current and the charging current to the storage battery or storage battery are zero. These issues also impose major constraints on the mounting design of satellites in that the external dimensions of the shunt circuits become larger. As described above, conventional devices have had drawbacks such as satellite malfunctions and failures due to heat generation in the shunt circuit, complicated thermal design, and restrictions on mounting design due to large external dimensions.

The purpose of the present invention is to eliminate these drawbacks, to continuously control the amount of current generated by the solar cell array, and to generate only the amount of current equal to the amount of current required by the load and storage battery, thereby preventing the generation of surplus current. The purpose of the present invention is to provide a solar battery power supply device.

<Means for Solving the Problems> The solar cell power supply device according to the present invention includes limiter solar cells connected in series to the solar cell array and mechanically tiltable so as to limit the output power of the solar cell array to a predetermined value. A solar cell controller that detects the output voltage of the solar cell array, compares it with a predetermined reference voltage, and controls the limiter solar cell so that the output power of the solar cell array reaches a predetermined value based on the comparison result. and a power controller for controlling the tilt angle.

<Function> When a state occurs in which surplus current is generated in the output of the solar cell array, the power controller detects this state and controls the solar cell controller to limit the power generated by the solar cell array.

<Example> The present invention will be explained in detail below with reference to the drawings.

FIG. 3 is a block diagram of an embodiment of the invention.
The power controller 5 in this figure compares a reference voltage from a charging/discharging control circuit 11 that controls the charging/discharging current to the storage battery 4 and a reference voltage from a reference voltage circuit 12 with the output voltage of the solar cell, and controls the solar cell based on the voltage. The control circuit 13 includes a control circuit 13 that sends a control signal to the device 8. This solar cell controller 8 includes a limiter solar cell 9 connected in series with the solar cell array, and a drive section 10 that mechanically controls the angle of the limiter solar cell 9 with respect to the solar direction using the control signal. configured.

Next, the operation of this embodiment will be explained.

First, when the output current I _SC of the solar cell array 2 becomes larger than the sum of the current I _L flowing to the load 3 and the charging current I _BAT to the storage battery (I _SC > I _L + I _BAT ), the power controller 5 detects the surplus current amount and sends a signal such that I _SC =I _L +I _BAT to the solar cell output control device 8.
Upon receiving this signal, the solar cell output control device 8 operates the drive unit 10 to change the angle of the limiter solar cell 9. Due to this angle change of the limiter solar cell 9, the amount of sunlight incident on the light receiving surface decreases, and the output current also decreases, so a limiter is applied to the output current of the solar cell array 2, limiting I _SC . I _SC = I _L + I _BAT becomes. This is because the output current of a solar cell is almost proportional to the amount of light incident on the light-receiving surface, and when a solar cell array is constructed by connecting multiple solar cell elements in series, the output current of the array is the lowest output current. This takes advantage of the characteristic that the value is suppressed by the value of the solar cell element.

FIG. 4 shows a characteristic diagram of changes in the voltage-current characteristics of a solar cell element depending on the inclination angle of the sun. Here, θ is the sunlight incident angle, which is the angle between the normal to the solar cell light-receiving surface and the sunlight. When sunlight enters from the normal direction of the solar cell light receiving surface (θ = 0°), V of characteristic line 14
-I characteristic, and as θ becomes larger than 0, V
-I characteristic line is 14 to 15, 15 to 16, 17
The characteristic line changes to , and the output becomes zero at θ=90°.

FIG. 5 shows a characteristic diagram of the short circuit current I _SC , the open circuit voltage V _OC , and the maximum power P _nax depending on the inclination angle of the corner electrode type solar cell element. I _SC and P _nax change approximately according to a function of cos θ, and for example, when the sunlight incident angle θ is set to 60°, I _SC and P _nax can be reduced by about 50%. This is because when the direction of the sun deviates from the normal direction of the solar cell light receiving surface, the effective value of the amount of sunlight incident on the solar cell light receiving surface decreases.

Figures 6a and 6b show a perspective view and a side view of the structure of an embodiment of the present invention. When sunlight is incident from a direction perpendicular to the light-receiving surface of the solar cell array 2, when there is no surplus current, the limiter solar cell 9 is parallel to the solar cell element 1 of the solar cell array 2 (θ=0°). is in a state of When surplus current occurs due to a decrease in load current, the power controller 5
The drive unit 10 of the solar cell output control device 8 is operated by a control signal from the limiter solar cell 9 to create an angle between the normal direction of the light-receiving surface of the limiter solar cell 9 and the direction of the sun.
The current generated by the solar cell array 2 is controlled.

Figure 7 shows the V of the solar cell to explain these relationships.
-I characteristic diagram. 18 is solar cell 9 for limita
This is a VI characteristic line when the angle of incidence of sunlight on θ=0. Letting the operating voltage of this circuit be V _BUS , the intersection of V _BUS and the VI characteristic line 18 is M, the point translated from M point to the current axis is I, the point translated parallel to the voltage axis is P, and the zero point is Letting L be the portion surrounded by points I, L, P, and N, the generated power at the operating voltage V _BUS , and I is the generated current. Then, surplus current is generated, and a control signal from the power controller 8 causes the drive unit 10 to
operates and the angle of incidence of sunlight on the limiter solar cell 9 is θ = θ ₁ , the VI characteristic line 19, and when the surplus current further increases and θ = θ ₂ , the VI characteristic line 20 Suppose it becomes. Operating voltage V _BUS and V-I characteristic line 19
Let the intersection point be N, and the points obtained by moving this N point in parallel to the current and voltage axes be J and P. When θ=θ ₁ , the area surrounded by points J, L, P, and N is for the limiter. This is the generated power controlled by the solar cell 9, and J is the generated current. Similarly, V _BUS and V-I
If the intersection with the characteristic line 20 is O, and the points obtained by moving this O point in parallel to the current and voltage axes are K and P, then the area surrounded by K, L, P, and O is when θ=θ ₂ This is the controlled generated power, and K is the generated current. In this way, by changing the angle of the limiter solar cell 9, the operating point changes from point M→N→O, and the output current can be continuously controlled until it becomes zero. Here, the output power becomes zero when θ≧90°. The load current, etc. increases, and I _SC < I _L
When +I _BAT occurs, the control signal from the power controller operates the drive unit so that the sunlight incident angle θ on the limiter solar cell light receiving surface becomes small, and the operating point of the circuit changes from O→N→M. can be changed continuously.

FIG. 8 shows a drive unit 10 that works to change the angle of the limiter solar cell 9 based on a signal from the power controller 5.
This is a concrete structural diagram of a thermal louver used in combination. 21 is a substrate to which a limiter solar cell is attached, 22 is a coiled bimetal, and 23 is a heater that generates heat to stretch the bimetal. When a surplus current is generated in this solar cell array, a part of the surplus current or load current is sent to the heater 23 according to a signal from the power controller 5, and the coil-shaped bimetal 22 is expanded by the heat generated at that time. The angle of the substrate 21 to which the battery 9 is attached is changed. This changes the angle of the limiter solar cell, making it possible to continuously control the output of the solar cell array.

<Effects of the invention> As explained above, by using limiter solar cells, it is possible to control the current generated by the solar cell array, so there is no need for a shunt circuit for consuming surplus power as in conventional devices. This eliminates the temperature rise due to heat generated by the shunt circuit.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional solar cell output control device, Fig. 2 is a characteristic diagram of a conventional solar cell output control device, Fig. 3 is a block diagram of an embodiment of the present invention, and Fig. 4 is a diagram of a solar cell output control device. VI characteristic diagram due to slope, 5th
The figure shows the angular characteristics of the output of a corner electrode type solar cell.
6 is a detailed diagram of the configuration of FIG. 3, FIG. 7 is a diagram of the operating characteristics of FIG. 3, and FIG. 8 is a diagram of the specific structure of the drive section of FIG. 6. In the figure, 1...Solar cell element, 2...Solar cell array,
3...Load, 4...Storage battery, 5...Power controller,
6...Shunt circuit, 7...V of solar cell array
-I characteristic line, 8...Solar cell output control device, 9...
...Solar cell for limiter, 10...Drive unit, 11...
...Charge/discharge control circuit, 12...Reference voltage circuit, 13
...Control circuit, 14-17...V of solar cell element
-I characteristic line, 18-20...V-I characteristic line when the limiter solar cell is connected, 21...Substrate, 2
2... bimetal, 23... heater.

Claims (1)

[Claims] 1 A solar cell array in which a predetermined number of solar cell elements are connected in series and parallel to obtain a predetermined power, and one solar cell element connected in series with this solar cell array or multiple solar cells connected in parallel. a limiter comprising a battery element and limiting the output power of the solar cell; a driving means for mechanically tilting the solar cell element surface of the limiter from the solar direction in response to a control signal; the solar cell array connected in series; Detecting the voltage applied to the load connected to both ends of the limiter, comparing this voltage value with a predetermined reference voltage value, and forming the control signal for controlling the inclination angle of the limiter according to the comparison result. A solar cell power supply device including a control circuit.