JPH0343821Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is designed to reduce the power generated by solar cells when shadows from antennas, observation probes, etc. appear on the surface of the solar cell array, and when the temperature of the solar cells increases due to increases in light intensity, etc. This invention relates to a solar cell power supply device that minimizes the amount of decrease in such cases.

Conventional solar battery power supplies are designed to reduce the reduction in power generated by solar cells due to the shadows of antennas, observation probes, etc. that appear on the surface of solar cell arrays such as artificial satellites. By connecting a shunt diode in parallel and bypassing the solar cell elements that were inactive due to the shadow, the solar cell array was prevented from becoming open. However, in this method,
Not only does the electromotive force of the solar cells in the bypassed area become zero, but the voltage drop due to the shunt diode also affects the solar cell array, so it is possible to prevent the solar cell array from becoming open, but it is possible to prevent the reduction in the generated power. It was difficult to do so.

Figures 1a and b show the configuration of the solar cell array when it is not shaded and its equivalent circuit diagram, and Figures 2a and b are the configuration diagrams when a part of the solar cell array is shaded. and their equivalent circuit diagrams, and FIG. 3 shows their output characteristic diagrams. When the solar cell array 2 mounted on the artificial satellite 1 is not shaded, all the solar cell elements 3 receive light and are in an operating state. In addition, a part of the solar cell array 2 mounted on the artificial satellite 1 may be in the shadow 5 of an antenna or an observation probe, etc.
When this occurs, some of the solar cell elements receive the shadow 5 and become inoperative. At this time, the solar cell element 4
A current flows through the shunt diode 6 to bypass the current.

In the output characteristic (V-I characteristic) diagram of the solar cell array in FIG. 3, x is the solar cell array 2 in FIG.
y is a characteristic curve when a part of the solar cell array 2 in FIG. 2 is exposed to a shadow 5. On the characteristic line x where the solar cell array 2 is not shaded at all and all of the solar cell elements are exposed to light, if the operating voltage of the solar cell power supply is V _BUS , the current value C at the operating point A on the output characteristics is obtained. On the other hand, on the characteristic line y where a part of the solar cell array 2 is shaded by the antenna, observation probe 5, etc., the non-operating solar cell has the opposite characteristics of a diode as shown in the equivalent circuit, and the solar cell array 2 is However, in order to prevent this open state, a shunt diode 6 is connected in parallel to the solar cell element. In this case its operating voltage
In V _BUS , the operating point is B, and only an extremely low current value D is obtained, resulting in a significant reduction in the generated power.

Note that by increasing the number of solar cell arrays 2 connected in series, it is possible to increase the current value at the operating voltage V _BUS even if some parts are shaded, but in this case, the number of solar cell elements increases, resulting in lower material costs and production This not only increases costs, but also increases weight, increases the size of solar panels, and has a major impact on the entire satellite system.

The purpose of this invention is to solve these problems and reduce the power generated by solar cells due to the effects of antennas, observation probes, etc. on the surface of the solar cell array by appropriately switching the electrical connections of solar cell elements. It is an object of the present invention to provide a solar cell power supply device in which the reduction is minimized.

The solar cell power supply device of the present invention includes a plurality of solar cell blocks each having a plurality of series-connected solar cell elements each connected in parallel with a shunt diode, and a solar cell power source by switchingly connecting both ends of these solar cell blocks in parallel or series. a relay constituting a battery array; voltage detection means for detecting that the output voltage of the solar battery array has decreased below a predetermined reference voltage;
The device includes relay driving means for driving the relay so that when the voltage detection means detects a decrease in the voltage, the parallel connection portions of the solar cell blocks are partially switched to series connection.

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

FIG. 4 is a block diagram of an embodiment of the present invention.
That is, in the solar cell array 2 in which the number of solar cell elements 7 required to obtain a predetermined power are electrically connected in series and parallel, the control section 8 outputs the monitor signal from the solar cell array 2 and the output of the reference voltage section 10. When the monitor signal becomes lower than the output signal of the reference voltage section 10, it sends a switching signal to the array switching section 9. This array switching section 9 functions to switch the connection of the solar cell elements 7 according to a signal from the control section 8, and the relay 11,
12 and its relay drive circuit.

FIGS. 5a and 5b are a block diagram and an equivalent circuit diagram when a part of the solar cell array 2 is shaded 5 in the present invention. As shown in the figure, relays 11 and 12 are provided for each block of the solar cell array 2, and when these blocks are not affected by the shadow 5, the contacts of the relays 11 and 12 are connected in parallel (on the black dot side). However, when these blocks receive the shadow 5, the control unit 8 determines the state and relays 11, 12
This control switches the contacts to series connection (white dot side).

FIG. 6 is an output characteristic diagram of the solar cell array shown in FIGS. 3 and 5, and shows the characteristics when the output characteristic line z is connected in series according to the present invention.

Next, the operation of this embodiment will be explained.

First, if the solar cell array 2 is not shaded by an antenna or observation probe, etc., that is, if the monitor signal from the solar cell array is higher than the output signal of the reference voltage section, the solar cell elements are paralleled as shown in Figure 1b. As shown by the output characteristic line x, a current value D is obtained at the operating point A at the operating voltage V _BUS . Next, a part of the solar cell array is shaded 5, and the monitor signal from the solar cell array is shifted to the reference voltage section 1.
When the output signal becomes lower than 0, a switching signal is sent from the control unit 8 to the array switching unit, and the solar cell elements are connected in series as shown in Fig. 5b, and the output characteristics at this time operate as shown by the characteristic line z. Approximately 1/2 current value F at voltage V _BUS .

In addition, the output characteristics when the array connection is not switched even though it is influenced by the conventional method is the characteristic line y,
Since the current value E is extremely low at V _BUS ,
It can be seen that by implementing the present invention, the amount of decrease in power generated by the solar cell array when exposed to shadows can be reduced.

Note that the present invention can be applied not only to artificial satellites but also to solar battery power supplies mounted on inner planet probes. In this case, as the solar cell array approaches the sun, the intensity of the light irradiated onto the solar cell array increases, so the temperature of the solar cells increases. In general, the temperature characteristics of solar cells are such that the higher the temperature, the lower the efficiency of converting light energy into electrical energy, and therefore the power generated by the solar cell array also decreases.

FIG. 7 shows a temperature characteristic diagram of the solar cell array output. In the figure, u is a characteristic line at normal temperature, w is a characteristic line at high temperature, and v is an output characteristic line when the connection of the solar cell element is switched at high temperature as an embodiment of the present invention.
When the operating voltage is V _BUS as shown in the figure, it can be seen that by implementing the present invention, the amount of decrease in power generated by the solar cell array at high temperatures can be reduced.

As explained above, according to the present invention, when a part of the solar array is shaded by an antenna or observation probe, or when the output is reduced due to high temperature,
Since the connection of the solar cell elements can be switched to parallel connection, there is an advantage that the amount of decrease in the power generated by the solar cells can be reduced.

[Brief explanation of the drawing]

Figures 1a and b are block diagrams of conventional solar cell arrays and their equivalent circuit diagrams. Figures 2a and b are block diagrams and their equivalent circuits when shaded by a portion of the solar cell array in Figure 1. The circuit diagram, Fig. 3 is an output characteristic diagram of the solar cell array, Fig. 4 is a block diagram of an embodiment of the present invention, and Fig. 5 a and b are diagrams when a part of the solar cell array according to the present invention is shaded. FIG. 6 is a diagram showing the output characteristics of the solar cell arrays shown in FIGS. 3 and 5, and FIG. 7 is a diagram showing the temperature characteristics of the solar cell array output. In the figure, 1...Artificial satellite, 2...Solar cell array, 3...Solar cell element in operating state, 4...Solar cell element in non-operating state,
5... Shadow, 6... Shunt diode, 7... Solar cell element, 8... Control section, 9... Array switching section, 10... Reference voltage section, 11, 12... Relay.

Claims (1)

[Scope of utility model registration request] A plurality of solar cell blocks each having a plurality of series-connected solar cell elements each connected in parallel with a shunt diode, and a relay that constitutes a solar cell array by switchingly connecting both ends of these solar cell blocks in parallel or series; Voltage detecting means for detecting that the output voltage of the solar cell array has decreased from a predetermined reference voltage, and a part of the parallel connected portions of the solar cell blocks being switched to series connected when the voltage detecting means detects the voltage decrease. and relay driving means for driving the relay.