JPH0332291B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a power supply device for an artificial satellite that obtains electric power by connecting a solar cell array to the main body of the artificial satellite.

[Prior art]

Conventionally, in artificial satellites that obtain power by connecting a solar cell array formed by electrically combining multiple solar cells to the satellite body, in order to control the output of the solar cell array to a DC voltage within a certain range. Generally, two methods are considered. The first
The method is as shown in Fig.
This is a method of combining the outputs of , leading them to a shunt circuit 7 in the satellite body via a slip ring 5 , and controlling the current voltage 8 by changing the current flowing through the shunt circuit 7 based on the output of the error amplifier 6 . .

That is, in FIG. 1, 1a, 1b, 1c are solar cell arrays, 2a, 2b, 2c are solar cell arrays (for control), 3a, 3b, 3c and 4a, 4
b, 4c are backflow prevention diodes, 5 is a slip ring for constantly electrically connecting the solar cell array pointing toward the sun and the satellite body, 6 is an error amplifier, 7 is a shunt circuit, and 8 is an output. A nonlinear characteristic of a solar cell in which the solar cell output voltage decreases by increasing the load current of the solar cell. The current flowing from the solar cell arrays (for control) 2a, 2b, 2c to the shunt circuit 7 is increased or decreased using the error amplifier 6 and the shunt circuit 7 so that the output voltage is at a constant value or below a constant value. Seshime 1st
This is a method of controlling the output voltage 8 shown in the figure within a certain range.

In the above example, solar cell arrays 1a, 1b,
1c and solar cell array (for control) 2a, 2
Although there are three b and 2c each, there is no necessarily limit to the number. Also, although the shunt circuit is placed inside the satellite body, it is also possible to place the shunt circuit closer to the solar array than the slip ring, in which case it is necessary to derive the error amplifier output to the shunt circuit via the slip ring. . As is well known, as the power generated by the solar cell array increases, this first method changes the "shunt voltage" (output voltage of the solar cell array (for control)) and the "shunt current" (backflow prevention diode 4a). ,4b,4c
The product of the shunt capacitance (the sum of the currents flowing through the capacitor), that is, the shunt capacitance, increases accordingly, making circuit design and component selection more difficult. Furthermore, since the amount of heat generated by the shunt circuit increases, there is a drawback that it becomes difficult to control the heat of the satellite itself.

The second method is to connect a plurality of shunt circuits 7a, 7b, 7c in parallel to the solar cell arrays (for control) 2a, 2b, 2c, respectively, as shown in FIG. The output of the amplifier 6 is compared with a predetermined operating reference level, and each shunt circuit 7a, 7b, 7
In this method, the output voltage 8 is controlled within a certain voltage range by sequentially controlling the impedance of the shunt circuits 7a, 7b, and 7c, and the total power consumed by the shunt circuits 7a, 7b, and 7c is reduced.

That is, in FIG. 2, 1a, 1b, 1c are solar cell arrays, 2a, 2b, 2c are solar cell arrays (for control), 3a, 3b, 3c and 4a,
4b and 4c are diodes for preventing backflow and connecting the solar cell array in parallel; 5 is a slip ring that connects the solar cell array and shunt circuit to the satellite body; 6 is a device for detecting and increasing the error of the output voltage 8 from the desired range. wide error amplification device, 7a, 7b,
7c is a solar cell array (for control) 2a, 2b, 2
shunt circuit corresponding to c, 8 is the power supply output voltage,
Shunt drive circuits 9a, 9b, and 9c drive shunt circuits 7a, 7b, and 7c when the output signal of the error amplifier 6 exceeds a predetermined level. Note that in Figure 2, 3 is the same as in Figure 1.
Although this example shows a case where several solar cell arrays (for control) are used, there is of course no limit to the number. This second
In the method shown in the figure, three shunt circuits 7
a, 7b, and 7c do not operate simultaneously, but operate within individual operating ranges associated with the output signal of the error amplifier 6, and within the operating range of each shunt drive circuit 9a, 9b, and 9c. Also, when the error signal is large, the impedance of the shunt circuits 7a, 7b, and 7c is made sufficiently low. That is, as the output signal of the error amplifier 6 increases, the shunt drive circuit 9a first enters the operating range, and the impedance of the shunt circuit 7a gradually decreases from a very large value, but the impedance of the shunt drive circuit 9b and the shunt drive circuit 9c The shunt circuits 7b and 7c do not operate yet, and the sympedances of the shunt circuits 7b and 7c remain very large.Next, when the output voltage of the error amplifier 6 exceeds the operating range of the shunt drive circuit 9a, the shunt drive circuit 9b moves out of its operating range. At this point, the impedance of the shunt circuit 7b gradually decreases from a very large value. At this time, the shunt drive circuit 9c does not operate. On the other hand, since the impedance of the shunt circuit 7a is sufficiently low, almost all the output current of the solar cell array (for control) 2a flows through the shunt circuit 7a, and the output voltage of the solar cell array (for control) 2a is very small. Therefore, the amount of heat generated by the shunt circuit 7a becomes small.

In this way, shunt drive circuits 9a, 9b, 9c
operate in order in response to the output signal of the error amplifier 6, and when the output signal of the error amplifier 6 exceeds the operating range of the shunt drive circuits 9a, 9b, 9c, the corresponding shunt drive circuits 7a, 7b, If the impedance of 7c is made sufficiently low, a shunt circuit with a very low impedance will have a very low voltage, so the amount of heat generated will be very small, and a shunt circuit with a very high impedance will have a current flowing through the shunt circuit. Since it is very small, the amount of heat generated is also very small, so the amount of heat generated by the shunt circuits 7a, 7b, and 7c as a whole is smaller than that in the first method.

In this way, the second method can reduce the capacity of the shunt circuit compared to the first method, and the fluctuation range of the amount of heat generated by the shunt circuit due to fluctuations in the power supply load is also reduced, which alleviates the drawbacks of the first method. be done. However, in this second method, a shunt drive circuit must be provided for each shunt circuit as shown in FIG. A comparison amplification circuit is required. Although these circuits are generally sensitive to temperature changes, they must be installed on the solar array side, for example on the solar array paddle, in space outside the satellite body, so the operating temperature conditions for these circuits are strict. Therefore, the circuit design becomes complicated. In particular, as satellites become larger and require more power, solar arrays also need to be larger. For example, when extending solar array paddles to tens of meters or more, line lengths for shunt loops must be increased. The problem of voltage drop or the influence on the error amplifier output signal, which is sensitive to external electromagnetic fields, becomes more and more significant.

[Summary of the invention]

This invention eliminates the above-mentioned conventional drawbacks,
As shown in FIG. 3, a shunt control circuit 1 is installed in the satellite body based on the output signal of the error amplifier 6.
0, the shunt circuit 7a should be operated optimally to keep the output voltage 8 within a predetermined range;
Select and decide whether to further increase or decrease the number of 7b and 7c, or maintain the status quo, and guide that information as a logic signal to the solar cell array side via the slip ring 5, and connect this signal and other signals to the shunt circuit. Shunt the shunt logic drive circuit that determines the drive state (ON or OFF state) of the shunt circuit of interest by combining the drive states (ON state with very low impedance of the shunt circuit and OFF state with very high impedance) The number of circuits to be provided and shunted for each circuit is controlled to increase or decrease sequentially, and the output voltage of the solar cell array is controlled within a certain range.

In this invention, there is no need for a reference voltage generation circuit in the shunt drive circuit or an amplification circuit for comparing the reference voltage generation circuit and the error signal, and the shunt circuit number increase/decrease status signal from the satellite itself is transmitted to other shunt circuits, such as adjacent shunt circuits. driving state (CN or OFF
Since the number of shunt circuits can be determined and the solar cell array output voltage can be controlled only by combinatorial logic with the state), the drawbacks of the first and second conventional methods can be eliminated.

That is, since the shunt circuit is either in an ON state with very low impedance or in an OFF state with very high impedance, the heat generated by the shunt as in the first method is extremely small.

In addition, since all shunt control signals are digital signals such as ON/OFF status signals or logic signals, the second method is to concentrate them in one place to control the heat of the shunt circuit and shunt drive circuit. It has the feature of eliminating complexity and the difficulty of circuit design and adjustment for temperature compensation.

[Embodiments of the invention]

FIG. 3 is a block diagram of the satellite power supply device according to the present invention. In the figure, 9a, 9b, 9c are the shy logic drive circuits, and 10 is the output voltage 8 based on the output signal of the error amplifier 6. A shaft control circuit 11 determines whether the number of shunt circuits to be operated is increased, decreased, or neither in order to achieve the voltage range, and derives the signal to the solar cell array side. The voltage smoothing capacitors 12 and 13 used are command signals from the shunt control circuit 10 for increasing and decreasing the number of operating shunt circuits, respectively.
For example, when increasing the number of shunt circuits, the command signal 12 is in the "1" state and 13 is in the "0" state, and when decreasing the number of shunt circuits, the command signal 12 is in the "0" state, 13 is in the "1" state, If there is no increase/decrease, a status signal of "0" for both 12 and 13 may be used. 14a, 14b, and 14c are the signals 12 and 13 in the shunt logic drive circuits 9a, 9b, and 9c, respectively, and the status signal 1 indicating the shunt drive state from the adjacent shunt logic drive circuit.
5a, 15b, 15c and 16a, 16b, 16
The shunt circuit drive signals 15a, 15b, and 15c turn on and off the shunt circuits 7a, 7b, and 7c according to the logic described later by combining the shunt logic drive circuits 9a, 9b, and 9c, respectively. The status signals shown (logically the same as 14a, 14b, 14c), 16a, 16b, and 16c are status signals that indicate the shunt drive OFF state rather than the shunt logic drive circuits 9a, 9b, and 9c, respectively.

In this example, the number of shunt circuits is three, but the number is not limited. First, if we consider the case where the load on this power supply is light, the output voltage 8 will be higher than the predetermined voltage when the nonlinear characteristics of the solar cell are assumed not to be controlled in a closed loop, and the error amplifier 6 will operate as a shunt circuit. An error signal is generated to activate the shunt circuit, and based on this signal, the shunt control circuit 10 naturally generates a control output to increase the number of activated shunt circuits. This signal is converted into a status signal or a digital signal of a logic symbol, and is input as a shaft circuit number increase command signal 12 to the shaft logic drive circuits 9a, 9b, 9c via the slip ring 5. On the other hand, at this time, the shunt circuit number reduction command signal 13 is not generated. To simplify the explanation, which shunt circuit drive signals 14a, 14
When both b and 14c are in the OFF state, the shunt logic drive circuit 9a changes the shunt circuit drive signal 14a to "1" and turns on the shunt circuit 7a since the shunt circuit number increase command signal 12 is "1".
At the same time, the status signal 15a indicating the shunt drive ON state is changed from "0" to "1". The shunt logic drive circuit 9b calculates the AND of the status signal 15a indicating the shunt drive ON state and the command signal 12 for increasing the number of operating shunt circuits. That is, if the increase command signal 12 is in the "1" state, the shunt circuit drive signal 14b is set in the "1" state, and the shunt circuit 7b is also turned on. When the increase command signal 12 changes to "0", the shunt circuit drive signal 14b remains "0" and the shunt circuit 7
b remains OFF. In this way, depending on the state of the increase command signal 12, the shunt circuits 7a to 7
By sequentially turning on the output voltages b and 7c, the voltage is lowered until the output voltage 8 falls below a predetermined value. Conversely, if the load on the power supply device is heavy and the number of shunt circuits is large, a command signal 13 for reducing the number of active shunt circuits is generated, for example, the shunt circuits 7a, 7
Assuming that both b and 7c are in the ON state, the shunt logic drive circuit first receives the shunt circuit drive signal 14c.
from “1” to “0” and shunt circuit 7c.
At the same time as turning off, a status signal 16c indicating the shunt drive OFF state is generated (in this example, it is changed from "0" to "1"). Even in this state, a signal instructing a reduction in the number of shunt circuits is generated. If so, in the shunt logic drive circuit 9b, the logical product of the status signal 16c indicating the shunt drive OFF state and the reduction command signal 13 for the number of active shunt circuits is performed, and the shunt circuit drive signal 14b is set to "0", and the shunt circuit 7b is set to the OFF state. As a result, the output voltage 8 is increased.

Similarly, by sequentially turning off the shunt circuits, the output voltage is controlled to fall within a predetermined value.

〔Effect of the invention〕

As described above, according to the present invention, the control signals between the satellite body and the solar cell array are digitized, and the shunt drive logic is determined only by the logic between these signals and the drive state of the adjacent shunt circuit. This allows the device to be resistant to temperature and external interference electromagnetic fields, and also makes it easy to separate and install the shunt circuit and shunt logic drive circuit in the vicinity of each solar cell array. Even when the area is large, the wiring for the shunt circuit can be reduced and the influence of line drops can be eliminated, making it particularly suitable as a power supply device for artificial satellites that require a large amount of power.

Note that in the above example, the solar cell array 1a,
1b, 1c and solar cell array (for control) 2a, 2
Although the explanation has been made using a partial system that distinguishes between solar cell arrays b and 2c, the present invention can also be applied to a full system that shunt-controls the entire solar cell array. In addition, although the shunt control circuit 10, shunt logic drive circuits 9a, 9b, 9c, etc. are shown as one system circuit, in actual application, a majority logic circuit may be adopted from the viewpoint of reliability improvement and failsafe. Processing such as detecting a fault and inhibiting or bypassing the logic can be easily achieved by modifications based on the present invention.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining a conventional power supply device for an artificial satellite, and FIG. 3 is a diagram showing an embodiment of the power supply device for an artificial satellite according to the present invention. 1 in the diagram
a, 1b, 1c are solar cell arrays, 2a, 2b,
2c is a solar cell array (for control), 3a, 3b,
3c is a backflow prevention diode, 4a, 4b, 4c are backflow prevention diodes (for shunt), 5 is a slip ring, 6 is an error amplifier, 7 is a shunt circuit,
8 is a power supply voltage, 9a, 9b, 9c are shunt drive circuits, 10 is a shunt control circuit, and 11 is a smoothing capacitor. Note that the same or equivalent parts are indicated by the same reference numerals.

Claims (1)

[Claims] 1 Compare a plurality of solar cell arrays formed by electrically combining a plurality of solar cells connected in parallel and the output voltage of the solar cell array with a preset reference voltage, and generate an error signal. an error amplifier, a plurality of shunt circuits respectively connected to the plurality of solar cell arrays, and a signal indicating an increase or decrease in the number of shunt circuits to be operated based on the output signal of the error amplifier. The shunt control circuit to be generated is connected to the shunt control circuit in a corresponding manner, and the shunt logic drive ON/OFF signal outputted from each other is combined with the logic of the output signal of the shunt control circuit to generate the corresponding shunt circuit. A power supply device for an artificial satellite, comprising a plurality of shunt logic drive circuits that are operated to keep the output voltage of the solar cell array constant.