Solar charging system

Abstract

Provided is a solar charging system capable of accurately estimating the power generation amount of a solar panel. A solar charging system includes a solar panel and an electronic control unit that controls power generation of the solar panel. The electronic control unit includes a first processing unit that derives a fill factor of the solar panel based on a short-circuit current of the solar panel, and a second processing unit that estimates the power generation amount of the solar panel based on the fill factor derived by the first processing unit, an open-circuit voltage of the solar panel, and the short-circuit current of the solar panel.

Description

Technical Field

[0001] This invention relates to a solar charging system comprising a solar panel and an electronic control unit for controlling the power generation of the solar panel. Background Technology

[0002] Patent document 1 discloses a solar charging control device that calculates the maximum power point (power generation) of a solar panel based on the open-circuit voltage and short-circuit current of the solar panel. If the calculated maximum power point is above a specified value, the device charges the generated power from the solar panel into the battery.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2021-086302 Summary of the Invention

[0004] When estimating the power generation of solar panels, a fill factor is sometimes considered as an indicator of the panel's performance. The value of this fill factor is affected by the amount of sunlight or the panel's temperature; therefore, using a fixed fill factor to estimate the power generation may result in inaccurate estimates (deterioration in calculation accuracy).

[0005] The present invention was made in view of the above-mentioned problems, and its purpose is to provide a solar charging system that can accurately calculate the power generation of solar panels.

[0006] To address the aforementioned issues, one aspect of the present invention is a solar charging system comprising: a solar panel; and an electronic control unit that controls the power generation of the solar panel. The electronic control unit includes: a first processing unit that derives the fill factor of the solar panel based on the short-circuit current of the solar panel; and a second processing unit that calculates the power generation of the solar panel based on the fill factor derived by the first processing unit, the open-circuit voltage of the solar panel, and the short-circuit current.

[0007] Invention Effects

[0008] According to the solar charging system of the present invention, the fill factor used to calculate power generation is changed based on the short-circuit current of the solar panel, which varies in accordance with the amount of solar irradiance. This suppresses deviations in the calculated values ​​caused by the influence of solar radiation, thus enabling high-precision calculation of the solar panel's power generation. Attached Figure Description

[0009] Figure 1 This is a schematic structural diagram of a solar charging system according to one embodiment of the present invention.

[0010] Figure 2 This is the IV characteristic diagram of a solar panel.

[0011] Figure 3 This is a PV characteristic diagram of a solar panel.

[0012] Figure 4 This is a flowchart of the power generation calculation and control (Example 1) executed by the solar ECU.

[0013] Figure 5 This is an example of the corresponding mapping diagram used in power generation estimation control (Example 1).

[0014] Figure 6 This is a flowchart of the power generation calculation and control (Example 2) executed by the solar ECU.

[0015] Figure 7 This is an example of the corresponding mapping diagram used in power generation estimation control (Example 2).

[0016] Figure 8 This is a flowchart of the power generation calculation and control (Example 3) executed by the solar ECU.

[0017] Figure 9 This is an example of a two-dimensional correspondence mapping diagram used in power generation estimation control (Example 3). Detailed Implementation

[0018] The solar charging system of the present invention focuses on the short-circuit current of solar panels, which is affected by solar radiation in the same way as the fill factor of solar panels. By appropriately changing the value of the fill factor based on the actual measured short-circuit current, the accuracy of the power generation calculation of solar panels is improved.

[0019] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0020] <Implementation Method>

[0021] [structure]

[0022] Figure 1 This is a diagram showing a schematic structure of a solar charging system 100 according to an embodiment of the present invention. Figure 1 The solar charging system 100 illustrated includes a solar panel 110, a solar ECU 120, and a battery 130. This solar charging system 100 can be installed in vehicles, etc.

[0023] Solar panel 110 is a power generation device that generates electricity by being exposed to sunlight, typically a solar cell module consisting of a collection of solar cell units. The amount of electricity generated by solar panel 110 depends on the amount of sunlight (solar radiation intensity) or the temperature of the panel. The electricity generated by solar panel 110 is output to solar ECU 120. This solar panel 110 can be installed, for example, on the roof of a vehicle.

[0024] Figure 2 The diagram illustrates the IV characteristic of the solar panel 110's power generation capacity. This IV characteristic represents the relationship between the voltage V (horizontal axis) and current I (vertical axis) of the solar panel 110 when it receives sunlight and generates electricity. The open-circuit voltage is the voltage value appearing at the output terminal of the solar panel 110 in the open state, i.e., when the operating current is set to "0". The short-circuit current is the current flowing at the output terminal of the solar panel 110 when the output terminal is short-circuited, i.e., when the operating voltage is set to "0". Furthermore, Figure 3 The illustration shows the PV characteristics of solar panel 110. Figure 3 In the example, solar panel 110 indicates that it can output maximum power Pmp when the operating voltage is voltage Vmp.

[0025] Battery 130 is a rechargeable battery, such as a lithium-ion battery or a lead-acid battery. This battery 130 is connected to the solar ECU 120 and can be charged using electricity generated by the solar panel 110. An auxiliary battery can be exemplified as the battery 130 mounted in the vehicle.

[0026] The solar ECU 120 is a connection point connecting the solar panel 110 and the battery 130, and is an electronic control unit (ECU) that can supply the generated power to the battery 130 by controlling the power generation of the solar panel 110. The electronic control unit typically includes a processor, memory, and input / output interfaces, etc. The processor reads and executes the program stored in the memory, thereby performing various processes.

[0027] The solar ECU 120 is configured to acquire the short-circuit current, open-circuit voltage, and temperature of the solar panel 110. Furthermore, the solar ECU 120 is configured to calculate the power generation of the solar panel 110.

[0028] [control]

[0029] Next, refer to Figures 4 to 9 The control performed in the solar charging system 100 according to this embodiment will be described.

[0030] (1)Example 1

[0031] Figure 4 This is a flowchart illustrating the processing sequence of the first example of power generation estimation control executed by the solar ECU 120 of the solar charging system 100. This first example of power generation estimation control begins when it is necessary to estimate the power generation of the solar panel 110.

[0032] (Step S401)

[0033] The solar ECU 120 acquires the open-circuit voltage and short-circuit current of the solar panel 110. This open-circuit voltage and short-circuit current can be acquired using the solar ECU 120 or voltage and current sensors (not shown) included in the solar panel 110.

[0034] If the open-circuit voltage and short-circuit current of the solar panel 110 are obtained through the solar ECU120, the process proceeds to step S402.

[0035] (Step S402)

[0036] The solar ECU 120 derives the fill factor of the solar panel 110 based on the short-circuit current of the solar panel 110 (first processing unit). This fill factor can be derived using a corresponding mapping diagram or mathematical formula prepared in advance in the storage unit, etc. Figure 5 This is an example of a mapping diagram showing the correlation between the short-circuit current and the fill factor of solar panel 110. Figure 5 The corresponding mapping diagram shown allows you to find the fill factor corresponding to the short-circuit current.

[0037] If the fill factor based on the short-circuit current of the solar panel 110 is derived through the solar ECU 120, the process proceeds to step S403.

[0038] (Step S403)

[0039] The solar ECU 120 calculates the power generation (electrical power) of the solar panel 110 based on the open-circuit voltage, short-circuit current, and fill factor derived in step S402 above (second processing unit). This power generation W can be calculated using the open-circuit voltage V, short-circuit current I, and fill factor Ff using the following formula.

[0040] W = V × I × Ff

[0041] If the solar ECU120 calculates the power generation of the solar panel 110 based on the open-circuit voltage, short-circuit current, and fill factor of the solar panel 110, then the power generation calculation control ends (Example 1).

[0042] As in the power generation estimation control in Example 1, by using a fill factor that is changed in accordance with the open-circuit voltage of the solar panel 110 to estimate the power generation of the solar panel 110, the error between the actual power generation and the estimated power generation can be reduced. An example is shown below.

[0043] Assuming scenarios with high solar radiation (short-circuit current: 5.5A) and low solar radiation (short-circuit current: 4A), the difference is compared between the conventional case where the fill factor of the solar panel 110 is fixed at "0.8" and the present invention where it varies from "0.8 (high short-circuit current) to 0.6 (low short-circuit current)". In the scenario with high solar radiation, when the actual power generation of the solar panel 110 is 100W, the estimated power generation is 96.8W (=22V×5.5A×0.8) in both the conventional and present invention scenarios, with a small error of 3.2W. On the other hand, when the actual power generation of the solar panel 110 in a scenario with low solar radiation is 50W, the power generation calculated based on the previous fixed value is 70.4W (=22V×4A×0.8), which is large with an error of 20.4W. In contrast, the power generation calculated based on the variable value of the present invention is 52.8W (=22V×4A×0.6), which is smaller with an error of 2.8W.

[0044] (2) Case 2

[0045] Figure 6 This is a flowchart illustrating the processing sequence of the second example of power generation estimation control executed by the solar ECU 120 of the solar charging system 100. This second example of power generation estimation control begins when it is necessary to estimate the power generation of the solar panel 110.

[0046] (Step S601)

[0047] The solar ECU 120 acquires the short-circuit current of the solar panel 110. This short-circuit current can be acquired using the solar ECU 120 or a current sensor (not shown) included in the solar panel 110.

[0048] If the short-circuit current of the solar panel 110 is obtained through the solar ECU120, the process proceeds to step S602.

[0049] (Step S602)

[0050] The solar ECU 120 derives the calculated power generation (electrical power) of the solar panel 110 based on the short-circuit current of the solar panel 110 (third processing unit). This power generation can be derived using a correspondence mapping diagram (first correspondence mapping diagram) or mathematical formula prepared in advance in the storage unit (first storage unit), etc. Figure 7This is an example of a correspondence mapping diagram showing the correlation between the short-circuit current of solar panel 110 and power generation. The power generation shown in this correspondence mapping diagram reflects a correction related to the deviation of the fill factor accompanying the variation in the short-circuit current of solar panel 110. Here, the corrected value can be obtained in advance based on actual measurements or simulations using solar panel 110. Figure 7 The corresponding mapping diagram shown allows you to find the power generation corresponding to the short-circuit current.

[0051] If the calculated power generation of the solar panel 110 based on the short-circuit current of the solar panel 110 is derived by the solar ECU 120, then this power generation calculation control ends (Example 2).

[0052] Based on the power generation calculation control in this second example, the power generation can be directly calculated from the short-circuit current of the solar panel 110, thus eliminating the need to obtain the open-circuit voltage of the solar panel 110 (simplifying the measurement system).

[0053] (3) Example 3

[0054] Figure 8 This is a flowchart illustrating the processing sequence of the third example of power generation estimation control executed by the solar ECU 120 of the solar charging system 100. This third example of power generation estimation control begins when it is necessary to estimate the power generation of the solar panel 110.

[0055] (Step S801)

[0056] The solar ECU 120 acquires the open-circuit voltage, short-circuit current, and panel temperature of the solar panel 110. This open-circuit voltage, short-circuit current, and panel temperature can be acquired using the solar ECU 120 or voltage sensors, current sensors, and temperature sensors (such as thermistors) not shown that are present in the solar panel 110.

[0057] In addition, the temperature of the solar panel 110 can be indirectly predicted by using the value of the open-circuit voltage of the solar panel 110, which varies according to the temperature of the solar panel, rather than by directly measuring the actual temperature through a temperature sensor or the like.

[0058] If the open-circuit voltage, short-circuit current and temperature of the solar panel 110 are obtained through the solar ECU120, the process proceeds to step S802.

[0059] (Step S802)

[0060] The solar ECU 120 derives the fill factor of the solar panel 110 based on the short-circuit current and panel temperature (4th processing unit). This fill factor can be derived using a two-dimensional correspondence mapping diagram (2nd correspondence mapping diagram) prepared in advance in the storage unit (2nd storage unit), etc. Figure 9 This is an example of a two-dimensional correspondence mapping diagram showing the correlation between the short-circuit current and temperature of solar panel 110 and the fill factor. Figure 9 The two-dimensional mapping diagram shown can be used to find the fill factor corresponding to the short-circuit current and the solar panel temperature.

[0061] If the fill factor based on the short-circuit current and temperature of the solar panel 110 is derived through the solar ECU120, the process proceeds to step S803.

[0062] (Step S803)

[0063] The solar ECU 120 calculates the power generation (electrical power) of the solar panel 110 based on the open-circuit voltage, short-circuit current, and fill factor derived in step S802 above (5th processing unit). The method for calculating this power generation is as described above.

[0064] If the solar ECU120 calculates the power generation of the solar panel 110 based on the open-circuit voltage, short-circuit current, and fill factor of the solar panel 110, then this power generation calculation control ends (Example 3).

[0065] As in the power generation estimation control in Example 3, the fill factor is derived not only based on the open-circuit voltage of the solar panel 110 but also on the panel temperature of the solar panel 110. Therefore, the error between the actual power generation of the solar panel 110 and the estimated power generation can be further reduced. An example is shown below.

[0066] Assuming the same solar irradiance (short-circuit current: 5.5A) and different scenarios such as solar panel temperature of 25℃ (open-circuit voltage: 22V) and 0℃ (open-circuit voltage: 23V), we compare the cases where the fill factor of solar panel 110 is set to "0.80 (panel temperature: 25℃)" and "0.85 (panel temperature: 0℃)". When the actual power generation of solar panel 110 at a panel temperature of 25℃ is 100W, the estimated power generation is 96.8W (=22V×5.5A×0.80), with an error of 3.2W. Conversely, when the actual power generation of solar panel 110 at a panel temperature of 0℃ is 108W, the estimated power generation is 107.5W (=23V×5.5A×0.85), with an error of 0.5W. Thus, without considering the temperature of the solar panel 110, the calculated power generation (101.2W = 23V × 5.5A × 0.80) using a fill factor of "0.80" when the panel temperature is 0℃ can be reduced by 6.8W = 108W - 101.2W.

[0067] <Function / Effect>

[0068] As described above, according to an embodiment of the present invention, the solar charging system 100 derives the fill factor of the solar panel 110 based on the short-circuit current of the solar panel 110, and calculates the power generation of the solar panel 110 based on the derived fill factor, open-circuit voltage, and short-circuit current. Alternatively, a correspondence map showing the correlation between the short-circuit current and power generation of the solar panel 110, with the deviation of the fill factor corrected, is used to derive the estimated power generation of the solar panel 110 based on the short-circuit current and the correspondence map. Alternatively, a correspondence map showing the correlation between the short-circuit current and panel temperature of the solar panel 110 and the fill factor is used to derive the fill factor based on the short-circuit current, panel temperature, and the correspondence map, and calculates the power generation of the solar panel 110 based on the derived fill factor, open-circuit voltage, and short-circuit current.

[0069] By employing these calculation methods, deviations in the calculated values ​​caused by the effects of solar radiation are suppressed, thus enabling high-precision calculations of the power generation of the solar panel 110. Therefore, the number of times the solar charging system 100 needs to be started in scenarios with low power generation can be reduced, thereby improving the system's power generation efficiency.

[0070] The present invention has been described above as one embodiment of the invention. However, the present invention can be understood not only as a solar charging system, but also as a method for performing a solar charging system, a program of the method, a computer-readable non-transitory storage medium storing the program, and a vehicle equipped with a solar charging system.

[0071] This invention can be used in vehicles and the like, where batteries are charged using electricity generated by solar panels.

[0072] Symbol Explanation

[0073] 100 - Solar charging system, 110 - Solar panel, 120 - Solar ECU, 130 - Battery.

Claims

1. A solar charging system, comprising: Solar panels; and An electronic control unit controls the power generation of the solar panels. The solar charging system is characterized in that... The electronic control unit includes: The first processing unit derives the fill factor of the solar panel based on the short-circuit current of the solar panel; and The second processing unit calculates the power generation of the solar panel based on the fill factor derived from the first processing unit, the open-circuit voltage of the solar panel, and the short-circuit current.

2. A solar charging system, comprising: Solar panels; and An electronic control unit controls the power generation of the solar panels. The solar charging system is characterized in that... The electronic control unit includes: The first storage unit stores a first correspondence map that corrects for the deviation of the fill factor of the solar panel and represents the correlation between the short-circuit current of the solar panel and the power generation of the solar panel. and The third processing unit derives the power generation based on the short-circuit current and the first corresponding mapping diagram.

3. A solar charging system, comprising: Solar panels; and An electronic control unit controls the power generation of the solar panels. The solar charging system is characterized in that... The electronic control unit includes: The second storage unit stores a second correspondence map showing the correlation between the short-circuit current and temperature of the solar panel and the fill factor of the solar panel. The fourth processing unit derives the fill factor based on the short-circuit current, the solar panel temperature, and the second corresponding mapping diagram; and The fifth processing unit calculates the power generation of the solar panel based on the fill factor derived from the fourth processing unit, the open-circuit voltage of the solar panel, and the short-circuit current.

4. The solar charging system according to claim 3, characterized in that, The temperature of the solar panel is derived from the open-circuit voltage.

Images