JP5454838B2 - Power supply device using solar cell and control method thereof - Google Patents

Description

  The present invention relates to a power supply device using a power storage module having a plurality of intermediate tap output terminals, and an intermediate tap for connecting the power storage module and the solar battery according to the voltage-power characteristics of the solar battery and the voltage of the intermediate tap output terminal of the power storage module. The present invention relates to an apparatus and method for controlling the output power of a solar cell by selecting one output terminal from a plurality of intermediate tap output terminals.

  1A and 1B are graphs showing curves representing the characteristics of solar cells. As shown in FIGS. 1 (a) and 1 (b), the solar cell has non-linear voltage-current characteristics shown in FIG. 1 (a) and voltage-power characteristics shown in FIG. 1 (b). Since it greatly depends on the amount of solar radiation and temperature, some output control means is required to extract an arbitrary output.

Further, in order to extract the energy of the solar cell to the maximum, it is necessary to operate at the operating voltage V _Pmax at which the output power becomes the maximum Pmax. Even if it is impossible to operate at V _Pmax , it is desirable to operate the solar cell at an operating voltage point where the output power is as close to Pmax as possible.

  As a solar cell output control means and a method for maximizing the output, there is a time ratio control using a DC-DC converter. However, conversion loss occurs by using a DC-DC converter, and switching noise corresponding to the switching frequency also occurs. Further, there is a problem that the circuit configuration becomes complicated by using the DC-DC converter.

  The present invention has been made under such circumstances, and it is possible to prevent the occurrence of conversion loss and the occurrence of switching noise, and a power supply device using a solar cell that does not require complicated circuit configuration. And it aims at providing the control method.

  In order to solve the above-described problem, one aspect of the power supply device according to the present invention includes a solar cell, a plurality of power storage elements connected in series, and a power storage module connected in parallel with the solar cell. A plurality of intermediate tap output terminals taken out from both ends of each storage element of the storage module, and switch means connected between the solar cell and each intermediate tap output terminal, and the voltage-power of the solar cell Based on the characteristics and the voltage of each intermediate tap output terminal, the output control of the solar cell is performed by selecting the intermediate tap output terminal connecting the solar cell and the power storage module.

  In order to solve the above-described problem, another aspect of the power supply device according to the present invention includes a solar cell, a plurality of power storage elements connected in series, and a power storage module connected in parallel with the solar cell. A plurality of intermediate tap output terminals taken out from both ends of each storage element of the storage module, and switch means connected between the solar cell and each intermediate tap output terminal, and the voltage-power of the solar cell Based on the characteristics and the voltage of the intermediate tap output terminal, the intermediate tap output terminal for connecting the solar cell and the power storage module is selected to control the output of the solar cell and control the charging power to the power storage module It is characterized by doing.

  The power supply device that controls charging power includes a balance circuit provided in parallel with the power storage module, and when the charging power to the power storage module is controlled, energy is exchanged between the power storage elements by the balance circuit. Thus, it is possible to suppress variations in voltage of each storage element.

  In the power supply device for controlling the charging power, the energy is directly exchanged between the storage element group on the higher potential side and the storage element group on the lower potential side than the selected intermediate tap terminal, and the charging power of each storage element It is possible to provide a DC-DC converter that suppresses variations in the above.

  In order to solve the above-described problem, one aspect of a method for controlling a power supply device according to the present invention is a power storage device having a plurality of intermediate tap output terminals taken out from series connection points of a plurality of power storage devices constituting a power storage module. A method for controlling a power supply device including a module and a solar cell, wherein a plurality of intermediates connecting the solar cell and a storage module based on voltage-power characteristics of the solar cell and a voltage of each intermediate tap output terminal The output control of the solar cell is performed by selecting one of the tap output terminals.

  In order to solve the above-described problem, another aspect of the method for controlling a power supply device according to the present invention is a power storage device having a plurality of intermediate tap output terminals taken out from series connection points of a plurality of power storage elements constituting a power storage module. A method for controlling a power supply device including a module and a solar cell, wherein a plurality of intermediates connecting the solar cell and a storage module based on voltage-power characteristics of the solar cell and a voltage of each intermediate tap output terminal By selecting one of the tap output terminals, the output of the solar cell is controlled and the charging power to the power storage module is controlled.

  By controlling the output of a solar cell as described above, a power supply device using a solar cell that prevents the occurrence of conversion loss and the occurrence of switching noise and does not require a complicated circuit configuration, and a control method thereof are provided. Can be provided.

  An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a circuit diagram of a power supply device for the principle description of the method for controlling the output of the solar cell in the present invention. The power storage elements C1 to C4 connected in series constitute a power storage module, and the connection points of adjacent power storage modules are intermediate tap output terminals 1 to 4, respectively. Each of the intermediate tap output terminals 1 to 4 is connected to the solar cell 10 and the load 12 via the switches S1 to S4, respectively. The solar cell 10 and the load 12 are directly connected, and any one of the switches S1 to S4 is turned on and connected to the power storage module.

As described above, the characteristics of the solar cell greatly change depending on the amount of solar radiation, temperature, and the like. Therefore, in order to appropriately control the electric power extracted from the solar cell, it is necessary to grasp the characteristics of the solar cell at a certain moment. As a method for estimating the characteristics of the solar cell, there are a method for estimating the solar cell characteristic from the amount of solar radiation based on past accumulated data, a method for estimating the solar cell characteristic by separately providing a reference solar cell for characteristic measurement, and the like. Although known, the method of estimating the characteristics of a solar cell is not limited to these. In the following description, it is assumed that the characteristics of the solar cell under certain solar radiation conditions and temperature conditions are known.

FIG. 3 is a diagram for explaining which of the switches S _{1 to} S ₄ is turned on with respect to a change in the characteristics of the solar cell when the control target power is constant, using the power supply device of FIG. FIG. Here, the control target power refers to the optimum power to be supplied to the load 12.

3 (a) to 3 (d) show how the characteristics of the solar cell differ greatly due to the influence of the amount of solar radiation and temperature, and V _{C1 to} V _C4 in the graph are the values at the intermediate tap terminals 1 to 4 in FIG. Corresponds to voltage. When any _{one of the} switches S _{1 to} S ₄ is turned on, the solar cell 10 operates at a voltage value equal to the voltage at the intermediate tap output terminal corresponding to the turned on switch. That is, the solar cell operates at any one of four voltage values V _{C1 to} V _C4 .

When the characteristics of the solar cell, such as a curve shown in FIG. 3 (a), the operating voltage of the solar cell by selecting the switch S ₁ is V _C1, and the solar cell, the control target power in those somewhat smaller than the control target power Output close power. In this case, selecting the switches S ₂ and switches S _3, (a i.e., large excess) output power of the solar cell is significantly deviate than the control target power. When you select the switch S _4, since the higher the V _C4 than the maximum voltage of the solar cell, it is impossible to obtain power from the solar cell. Therefore, when the characteristics of the solar cell as shown in FIG. 3 (a), by selecting the switch S _1, it is possible to approach the most output power of the solar cell to the control target power.

Similarly, when the characteristics of the solar cell are like the curves shown in FIGS. 3B to 3D, the output power of the solar cell is controlled by selecting the switches S _{2 to} S ₄ , respectively. The closest to electric power.

FIG. 4 is different from FIG. 3 in order to explain which of the switches S _{1 to} S ₄ is turned on in order to take out the power close to the maximum power from the solar cell 10 using the power supply device of FIG. FIG. When the switch S ₁ is selected when the characteristics of the solar cell are like the curve shown in FIG. 4A, the operating voltage of the solar cell is V _C1 , and the solar cell outputs power close to the maximum power. When you select the S ₂ to S _4, since the higher the V _C2 ~V _C4 than the maximum voltage of the solar cell, it is impossible to obtain power from the solar cell.

When the switch S ₁ is selected when the characteristics of the solar cell are like the curve shown in FIG. 4B, the voltage of the solar cell is V _C1 , which is significantly lower than the maximum power from the solar cell. Only electric power can be obtained. If you select switch S _2, the voltage of the solar cell becomes V _C2, solar cell outputs electric power close to the maximum power. When the switches S ₃ and S ₄ are selected, V _C3 and V _C4 are higher than the maximum voltage of the solar cell, so that power cannot be obtained from the solar cell. Therefore, when the characteristic of the solar cell, such as a curve shown in FIG. 4 (b), can draw power close to the maximum power from the solar cell by selecting the switch S _2.

Similarly, when the characteristics of the solar cell are as shown in FIGS. 4C to 4D, the power close to the maximum power can be extracted from the solar cell by selecting the switches S ₃ and S ₄ , respectively.

  In the operation described above, when the output power of the solar cell is excessive as compared with the power required by the load, the excess power is used as the charging power for the power storage module via the selected switch. On the other hand, when the output power of the solar battery is insufficient compared with the power required by the load, the insufficient power is supplied from the power storage module via the selected switch.

  As described above, since the power storage module takes charge of excess and deficiency, only the power storage element on the lower potential side than the selected intermediate tap output terminal is charged or discharged. As a result, the charge / discharge state varies between the high potential side power storage element group and the low potential side power storage element group of the selected intermediate tap terminal.

  Therefore, in such a case, as shown in FIG. 5, it is conceivable to provide a balance circuit 20 in parallel with the power storage module and exchange energy between the power storage elements. Examples of the balance circuit 20 include a switch capacitor connected between each storage element and a switch unit that switches connection between each switched capacitor and the two adjacent storage elements, It is possible to use a coil configured between switch elements and switch means for switching the connection between each coil and two power storage elements adjacent to each coil.

  Instead of using the balance circuit 20 of FIG. 5, a DC-DC converter 22 can be used as shown in FIG. The DC-DC converter 22 directly exchanges energy between the storage element group on the higher potential side and the storage element group on the lower potential side than the selected intermediate tap terminal. Such direct energy exchange can prevent variations in charge / discharge states.

FIG. 7 shows that in the power supply apparatus shown in FIGS. 5 and 6, each of the storage elements C _{1 to} C ₄ is uniformly charged by charging the storage module while the solar cell 10 supplies power to the load 12. It is a figure for demonstrating a state to go. When the storage elements C _{1 to} C ₄ are uniformly charged, the voltages V _{C1 to} V _{C4 at the} intermediate tap terminals 1 to 4 rise uniformly as shown in FIGS. 7 (a) to (d). I will do it.

Here, a description will be given of a case where charging is performed by taking out as much electric power as possible from the solar cell 10. When the switch S ₁ is selected when the voltages of the intermediate tap terminals 1 to 4 are as shown in FIG. 7A, the operating voltage of the solar cell 10 is V _C1 , which is much larger than the maximum power from the solar cell 10. Only low power can be obtained. The same applies when the switches S ₂ and S ₃ are selected. The case shown in FIG. 7 (a), when selecting the switches S _4, the voltage of the solar cell 10 becomes V _C4, it is possible to output the power close to the maximum power. Here, the difference between the electric power of the solar battery 10 and the electric power of the load 12 is the charging electric power.

As charging proceeds, the voltage of each storage element rises, the voltage at each intermediate tap output terminal rises, and when V _{C1 to} V _C4 become as shown in FIG. 7B, switches S ₁ and S ₂ are selected. Then, the operating voltage of the solar cell 10 becomes V _C1 and V _C2 , and only power much lower than the maximum power can be obtained from the solar cell. On the other hand, when the switch S ₄ is selected, the operating voltage of the solar cell 10 is as high as V _C4 , but only power significantly lower than the maximum power can be obtained from the solar cell 10. In the case shown in FIG. 7 (b), when selecting the switches S _3, the operating voltage of the solar cell 10 can output a power close V _C3, and the the maximum power. Here, the difference between the electric power of the solar battery 10 and the electric power of the load 12 is the charging electric power.

Similarly, when charging proceeds and the voltages at the intermediate tap terminals are as shown in FIGS. 7C and 7D, the solar cell is selected by selecting the switches S ₂ and S ₁ , respectively. The electric power close to the maximum electric power can be drawn from 10 and a large charging electric power can be obtained.

In the above description, the case where each of the power storage elements C _{1 to} C ₄ is uniformly charged by the balance circuit 20 or the DC-DC converter 22 has been described. However, each power storage element does not have a balance circuit or a DC-DC converter. Even in a power supply device having a non-uniform voltage, the charging power is also controlled by appropriately selecting the intermediate tap terminal to be connected to the solar cell according to the voltage-power characteristics of the solar cell and the voltage of each intermediate tap terminal. be able to.

In the above description, the case where the power storage module operates the solar cell with only four types of operating voltages (V _{C1 to} V _C4 ) using four series power storage elements has been described. It is possible to operate. In a power storage module having a large number of series and a large number of intermediate tap output terminals, the type of operating voltage of the solar cell increases (the same number as the intermediate tap output terminals), so that fine power control can be performed.

Further, the intermediate tap output terminal is not necessarily provided for each power storage element, and arbitrary output control can be performed if it is intentionally arranged. For example, if the intermediate tap output terminals are intensively provided so that many intermediate tap terminal voltages exist in the vicinity of V _Pmax , it is possible to finely control the vicinity of the maximum power of the solar cell.

  The present invention can be used for a mobile power source, a household power source, a solar power generation device, a remote power source, and the like.

It is the graph which showed the curve showing the characteristic of a solar cell. It is a circuit diagram of the power supply device for the principle description of the method of performing output control of a solar cell. Using the power supply of FIG. 2, when the control target power is constant, is a diagram for explaining how to turn on any Uchii switches S ₁ to S ₄ for changes in characteristics of the solar cell . FIG. 3 is a diagram for explaining which _one of switches S _{1 to} S ₄ is turned on in order to extract electric power close to the maximum electric power from the solar cell 10 using the power supply device of FIG. 2. It is a circuit diagram of the circuit which added the balance circuit to the power supply device of FIG. FIG. 3 is a circuit diagram of a circuit obtained by adding a DC-DC converter to the power supply device of FIG. 2. By charging the battery module while supplying power to the solar cell 10 is a load 12 is a diagram for explaining how the electric power storage device C ₁ -C ₄ Yuku is uniformly charged.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Solar cell 12 Load 20 Balance circuit 22 DC-DC converter

Claims (1)

Solar cells,
A power storage module composed of a plurality of power storage elements connected in series, connected in parallel with the solar cell,
A plurality of intermediate tap output terminals that are taken out from both ends of part or all of the electricity storage elements of the electricity storage module,
Switch means connected between the solar cell and each intermediate tap output terminal;
A balance circuit provided in parallel with the power storage module;
Based on the voltage-power characteristics of the solar cell and the voltage of the intermediate tap output terminal that are grasped in advance, the output power of the solar cell is closest to the control target power, or the maximum output of the solar cell In order to obtain the output power closest to the power, the switch means selects the intermediate tap output terminal for connecting the solar cell and the power storage module to perform output control of the solar cell, and charge power to the power storage module. To control the charging power to the power storage module by selecting the intermediate tap output terminal by the switch means,
When controlling the charging power to the power storage module, the balance circuit performs energy exchange between the power storage elements so as to suppress variations in the voltage of each power storage element,
Further, the DC− is configured to directly control energy between the storage element group on the higher potential side and the storage element group on the lower potential side than the selected intermediate tap terminal to suppress the voltage variation of each storage element. A power supply device comprising a DC converter .

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