JP2611724B2 - 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 device using a solar cell output as a power supply, and more particularly to a power supply device mounted on a satellite.

[0002]

2. Description of the Related Art FIG. 3 is a block circuit diagram showing a conventional solar cell power supply. Electric power is supplied from the conventional solar cell power supply to the temperature control heater circuit 5 through the following route. First, power generated in the solar cell circuit 1 is supplied to the main bus line 12 through the blocking diode 10. The electric power on the main bus line 12 is supplied to the secondary battery 4 through the charge control circuit 3 and is supplied to the heater circuit 5 through the heater control circuit 7. To the load circuit 6,
Power is supplied directly from the main bus line 12. The surplus power after being supplied to the secondary battery 4, the heater circuit 5, and the load circuit 6 is consumed by the upper limit voltage limiting circuit 2. When the generated power of the solar cell circuit 1 is reduced or stopped (for example, in the shade)
3 supplies the power stored in the secondary battery 4 to the heater circuit 5 and the load circuit 6 through the discharge diode 11. The heater control circuit 7 detects the temperature of a temperature control unit (not shown) and controls the heater switch 8 to control the amount of power consumed by the heater circuit 5. The resistance value of the heater circuit 5 is set so that the temperature of the temperature control unit can be maintained within a predetermined range even at the minimum voltage _VL of the secondary battery 4. Since the resistance value of the heater circuit 5 was constant, when the power was supplied from the solar cell circuit 1 and the voltage of the main bus line 12 was operating at the upper limit voltage, the voltage was continuously applied to the heater circuit 5. In this case, the temperature rises beyond a predetermined range. Therefore, the main bus line 1
When the voltage of 2 is high, the temperature control is performed by adjusting the ON period of the heater switch 8 of the heater control circuit 7.

Here, the operating characteristics of the solar cell will be described in order to facilitate understanding of the characteristics of the solar cell circuit 1. The solar cell circuit 1 is configured by connecting a plurality of solar cells in series. FIG. 4 shows the current-voltage characteristics of the solar cell, and FIG. 5 shows a measurement circuit thereof. The standard solar cell (135.
3 mW / cm ² ), the output characteristic is about 0.31 A in a short-circuit state (R = 0Ω in FIG. 5). Even if R is gradually increased, the current hardly changes.
This is a constant current range, and when the voltage reaches a certain level, the current decreases to about 0.6 V at R = ∞. The current in the short state I _SC, referred to the voltage of the open and V _{O C.} I
The value of _SC is almost proportional to the sunlight intensity, and is also proportional to the area of the solar cell. V _OC is determined by the structure of the solar cell and does not depend on sunlight intensity. G _a
The _AS cell has higher voltage and lower current characteristics than the silicon cell.

FIG. 6 shows the relationship between the current I and the power W _O with respect to the voltage V in a silicon single crystal solar cell.

[0005]

[SUMMARY OF THE INVENTION] As described above, the resistance value R ₅ of the heater circuit 5 is smaller set up to control the temperature of the temperature control unit even top resistor voltage V _L of the secondary battery 4 within a predetermined range since the, when the voltage of the main bus line 12 is operating at the upper limit voltage V _H is the power consumption W ₅ of the heater circuit 5 becomes a value greatly exceeding the required amount. Therefore, in the conventional solar battery power supply device, the lowest generation of the photovoltaic cell circuit 1, the power consumption of the heater circuit 5 of the upper limit voltage V _H, the power consumption W ₆ of the rechargeable battery charging power W _C and the load circuit 6 It must be greater than or equal to the sum power. As described above, in the solar cell power supply device, the voltage changes in accordance with the generated power, so that the power consumption W ₅ in the heater circuit 5 fluctuates in accordance with the generated power, that is, the amount of light received in the solar cell circuit 1. The power capacity that can be consumed under the maximum generated voltage (at the standard value) in the circuit 1 is required for the solar cell circuit 1. As described above, the conventional solar cell power supply device has a disadvantage that the solar cell circuit 1 having a much larger capacity than the power originally consumed by the heater circuit 5 is required. That is,
The conventional power supply has a problem to be solved regarding the required capacity of the solar cell circuit 1.

[0006]

In order to solve the above-mentioned problems, the present invention provides the following means. (1) a plurality of solar cell circuits, a main bus line connected to the solar cell circuits via a backflow prevention diode, and a secondary battery receiving a charging current from the main bus line via a charge control circuit; A heater connected to the main bus line, a circuit for limiting an upper limit voltage VH of the main bus line, and a resistance element, wherein a temperature of a predetermined portion is controlled by heat generated by a current flowing through the resistance element A circuit, a discharge diode connecting the output of the secondary battery to the load circuit and the heater circuit when the output voltage of the solar cell circuit drops below a predetermined value, and the heater inserted in series with the heater circuit, A heater control circuit for controlling the generation of heat by interrupting the flow path of the current supplied to the circuit in accordance with the temperature of the predetermined portion; Wherein the heater circuit comprises:
It is connected to a part of the plurality of solar cell circuits through a heater bus line and a backflow prevention diode, and is connected through the heater bus run and the backflow prevention diode.
The solar cell circuit connected to the heater circuit
When outputting a voltage of the same magnitude as the upper limit voltage VH,
A solar cell power supply device that outputs large power .

[0007]

[0008]

According to the present invention, a heater bus line is provided for a current path supplied to the heater circuit. Some of the plurality of solar cell circuits are connected to both the main bus line and the heater bus line via separate backflow prevention diodes (blocking diodes) for each bus line. Such a configuration can Orisei the power consumed in the heater circuit when the output voltage of the solar cell circuit reaches the upper limit voltage V _H, can thus reduce the power capacity of the entire solar cell circuit. The solar cell circuit can be reduced in size due to the smaller power capacity. As the solar cell circuit connected to the heater circuit via the heater bus line, by using one that generates the maximum power at the upper limit voltage _VH , the capacity of the entire solar cell circuit can be minimized, The overall size of the solar cell circuit can be minimized.

[0009]

Next, the present invention will be described in more detail with reference to examples. FIG. 1 is a block circuit diagram showing one embodiment of the present invention. The solar cell circuit 1a is connected to the main bus line 12, and the solar cell circuit 1b is connected to the main bus line 12 and the heater bus line 13. The heater bus line 13 is connected to the heater circuit 5, and when the solar cell circuit 1 b generates power, the power is supplied to the heater circuit 5 through the heater bus line 13. The switch 9 is turned on during the period when the solar cell circuit 1 b stops generating power, and the power of the secondary battery 4 is supplied to the heater circuit 5 through the discharge diode 11.

Heater bus line 1 of the solar cell circuit
[The number of solar cell circuits connected in parallel (the solar cell circuit shown by reference numeral 1b in Fig. 1)] number of circuits to be connected to 3 is determined by the resistance value R ₅ of the heater circuit 5. Here, one solar cell circuit is formed by connecting ten solar cells in series. Required power of heater circuit 5 (immediately fixed value)
Is selected when the number of circuits is selected so as to be able to be supplied at the minimum voltage V _L of the secondary battery 4, the most efficient solar cell circuit configuration is obtained.

FIG. 2 shows the power consumption W ₅ of the heater and the generated power characteristic W of the solar cell circuit connected to the heater bus line 13.
_1b shows the relationship. W _1b corresponds to W _O in FIG. In the conventional circuit shown in FIG. 3, the solar cell circuit to output power W _P at the upper limit voltage V _H to power the heater circuit 5 is required. In contrast, in the embodiment of FIG. 1, since it is possible to supply the minimum necessary heating power W _L at the operating point 18, it is sufficient to constitute a solar cell circuit for outputting a power W _H at the upper limit voltage V _H .

Next, the operation of the conventional power supply device of FIG. 3 and the embodiment of FIG.
The effect will be described in comparison. In the conventional example now to Figure 3, 50 V upper limit voltage V _H of the main bus lines 12, 30 V and minimum voltage V _L of the secondary battery 4, the power requirements W ₆ of the load circuit 6 60
0 W, 200 W charging power W _C when charging by the charge control circuit 3 to the secondary battery 4, the minimum required power W _L of the heater circuit 5 and 300 W. In the particular circuit, since minimum necessary power W _L of the heater circuit 5 is 300W at time minimum voltage V _L of the secondary battery 4 is 30 V, the resistance R ₅ of the heater circuit 5 R ₅ = V _L ² / W ^{_{L = 30 2/300 = 3Ω}} (1)
Must be selected.

In such a solar battery power supply device, when the main bus line 12 reaches the upper limit voltage V _H = 50 V, the power W _P output from the solar battery circuit 1 is W _P = W ₆ + W _C + W _L = 600 W + 200 W + 50 ² / 3W = 800W + 833W = 1633W (2) When the required power W _L is the voltage of the main bus line 12 from a 300W heater circuit 5 becomes the upper limit value V _H, the heater switch 8 300/833 = 0.3
It operates at a duty ratio of 6. The period of the heater switch 8 is OFF, the upper limit voltage limiting circuit 2 by consuming power to the shunt resistor, the voltage of the main bus line 12 is Seigo so as not to exceed the upper limit voltage V _H.

FIG. 7 is a diagram showing power characteristics of the conventional solar cell power supply of FIG. As shown in the figure, when the voltage of the main bus line 12 is the upper limit voltage V _H = 50 V, the power consumption of the heater circuit 5 is 833 W, the other power consumption is 800 W, and the total power consumption is 1633 W.

Next, consider the power in the power supply device of the embodiment of FIG. At this time, the voltage and power of each part of the power supply device shown in FIG. 1 are the same as those in the conventional power supply device shown in FIG. The output power W _P1a of the solar cell circuit 1a is W _P1a = W ₆ + W _C = 800 W (3) (FIG. 8). However, it is assumed that power is supplied to the main bus line 12 only from the solar cell circuit 1a. On the other hand, the solar cell circuit 1b satisfies a required power capacity by supplying at least power of W _L = 300 W to the load of the heater circuit 5 having a resistance value of R ₅ = 3Ω when the output voltage V _L = 30 V. When the intensity of sunlight increases and the output voltage reaches the upper limit V _H = 50 V, the solar cell circuit 1b having such a power capacity has a power supply capacity of about 500 according to the characteristic line W _{1b in} FIG.
W power is generated. In other words, the solar cell circuit 1b
When the output voltage is the upper limit voltage of 50 V, 5
It is sufficient if the output capacity is 00W. That is, the output power W _P1b of the solar cell circuit 1b at the upper limit voltage V _H is W _P1b = 500 W (4) (FIG. 9).

Therefore, in the embodiment of the present invention, the power capacity W _P obtained as the sum of the solar cell circuits 1a and 1b is W _P = W _P1a + W _P1b = 800W + 500W = 1300W (5)

As is clear from the comparison of the equation (5) with the equation (2), in the embodiment of the present invention, the power is reduced by W _D = 1633W-1300W = 333W (6) as compared with the conventional solar cell power supply. A solar cell circuit with sufficient capacity is sufficient.

[0018]

As described above, according to the present invention, the power supply to the heater circuit is performed not by the main bus line but by the heater bus connected to the solar cell circuit configured according to the resistance value of the heater circuit. Supplying from the line has the effect of reducing the capacity of the solar cell circuit, and thus the size thereof.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a solar cell power supply device according to one embodiment of the present invention.

FIG. 2 is a diagram showing heater power consumption characteristics and output power characteristics of a solar cell circuit connected to a heater bus line in the embodiment of FIG.

FIG. 3 is a circuit block diagram of a conventional solar cell device.

FIG. 4 is a current-voltage characteristic diagram of a solar cell.

FIG. 5 is a diagram showing a circuit for measuring the characteristics of FIG.

FIG. 6 shows a voltage V in a silicon single crystal solar cell.
FIG. 4 is a characteristic diagram showing a relationship between current I and power W _O with respect to FIG.

FIG. 7 is a diagram showing power characteristics in the conventional solar cell power supply device of FIG. 3;

FIG. 8 is a diagram showing output power characteristics of the solar cell circuit 1a in the embodiment of FIG.

FIG. 9 is a characteristic diagram showing a relationship between output power of the solar cell circuit 1b and power consumption of the heater circuit 5 in the embodiment of FIG.

[Explanation of symbols]

 1, 1a, 1b Solar cell circuit 2 Upper limit voltage limiting circuit 3 Charge control circuit 4 Secondary battery 5 Heater circuit 6 Load circuit 7 Heater control circuit 8 Heater switch 9 Changeover switch 10 Blocking diode 11 Discharge diode 12 Main bus line 13 Heater bus line

Claims (1)

(57) [Claims] 1. A plurality of solar cell circuits, a main bus line connected to these solar cell circuits via a backflow prevention diode, and a secondary battery receiving a charging current from the main bus line via a charge control circuit. A load connected to the main bus line, a circuit for limiting an upper limit voltage VH of the main bus line, and a resistance element, wherein a temperature of a predetermined portion is controlled by heat generated by a current flowing through the resistance element. Heater circuit, and a discharge diode that connects the output of the secondary battery to the load circuit and the heater circuit when the output voltage of the solar cell circuit drops below a predetermined value, and is inserted in series with the heater circuit, A heater control circuit for controlling the generation of heat by interrupting the flow path of the current supplied to the heater circuit in accordance with the temperature of the predetermined portion. In the power supply device, the heater circuit is connected to a part of the plurality of solar cell circuits through a heater bus line and a backflow prevention diode, and is connected to the heater bus line and the backflow prevention diode through the heater bus line and the backflow prevention diode.
The solar cell circuit connected to the heater circuit is
The maximum when outputting the same voltage as the upper limit voltage VH
A solar cell power supply device for outputting electric power.