Solar power generation control device

Abstract

To provide a solar power generation control device capable of shortening time required to specify a maximum power point of a solar panel and suppressing power generation efficiency deterioration of the solar panel.SOLUTION: A solar power generation control device that controls power generation of a solar panel includes: a first control part that derives, by MPPT control, a control voltage for causing the solar panel to generate a maximum power based on an output power of the solar panel; a second control part that derives a correction voltage for correcting the control voltage based on an output current of the solar panel; and a third control part that controls power generation of the solar panel by a voltage used for correcting the control voltage with the correction voltage.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a solar power generation control device that controls the power generated by a solar panel. [Background technology]

[0002] Patent Document 1 discloses a power generation system using a solar panel (solar cell module). The power generation system described in Patent Document 1 executes MPPT (Maximum Power Point Tracking) control, which controls the output voltage and output current of the solar panel to follow values ​​corresponding to the maximum power point of the solar panel. In this MPPT control, when the power generation power of the solar panel changes due to a change in the solar radiation state, the maximum power point of the solar panel is constantly searched for using a method such as a hill climbing method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-091431 A Summary of the Invention [Problem to be solved by the invention]

[0004] MPPT control using the hill climbing method searches for the maximum power point of the solar panel by increasing and decreasing the control voltage that commands the operation of the DCDC converter by a specified step voltage. Therefore, when a sudden change in solar radiation occurs on the solar panel, such as when the solar panel goes from being in the sun to being in the shade, the speed of the MPPT control cannot quickly follow the change in solar radiation, and it takes time to identify the maximum power point of the solar panel. The longer it takes from the change in solar radiation to identifying the maximum power point, the lower the power generation efficiency of the solar panel becomes.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a solar power generation control device that can shorten the time required to identify the maximum power point of a solar panel and suppress a decrease in the power generation efficiency of the solar panel. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the disclosed technology is a solar power generation control device that controls power generation of a solar panel, and includes a first control unit that derives a control voltage for causing the solar panel to generate maximum power through MPPT control based on the output power of the solar panel, a second control unit that derives a correction voltage for correcting the control voltage based on the output current of the solar panel, and a third control unit that controls power generation of the solar panel using a voltage corrected by the correction voltage. Effect of the Invention

[0007] According to the solar power generation control device of the present disclosure, the time required to identify the maximum power point of the solar panel can be shortened, and a decrease in the power generation efficiency of the solar panel can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic configuration diagram of a solar power generation system including a solar power generation control device according to an embodiment of the present invention; [Diagram 2] FIG. 13 is a diagram showing an example of a voltage correction map. [Diagram 3] A diagram showing an example of an IV curve of a solar panel depending on the solar radiation condition. [Figure 4] An example of the PV curve for a solar panel [Diagram 5] An example of the PV curve for a solar panel DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The solar power generation control device of the present disclosure focuses on the fact that the output current of a solar panel changes significantly according to the fluctuation of solar radiation on the solar panel, and corrects the control voltage according to the maximum power point searched for by hill climbing using MPPT control with a correction voltage that can be dynamically changed according to the output current of the solar panel. As a result, when the control voltage of a solar panel has shifted its maximum power point due to a sudden fluctuation of solar radiation, the hill climbing start voltage of the MPPT control can be quickly shifted to the vicinity of the maximum power point by the correction voltage, thereby shortening the time until the maximum power point of the solar panel is identified. Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0010] <Embodiment> [composition] Fig. 1 is a diagram showing a schematic configuration of a solar power generation system 1 including a solar power generation control device 40 according to an embodiment of the present disclosure. The solar power generation system 1 illustrated in Fig. 1 includes a solar panel 10, a sensor 20, a DC-DC converter 30, and a solar power generation control device 40. In Fig. 1, connection lines through which power is transmitted are indicated by thick lines, and connection lines through which control signals other than power, detection values, etc. are transmitted and received are indicated by thin arrow lines.

[0011] This solar power generation system 1 can be mounted on vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs).

[0012] The solar panel 10 is a device capable of generating power according to the amount of sunlight irradiated, and is typically an assembly of solar cells. The solar panel 10 outputs the generated power to the DC-DC converter 30 via the sensor 20.

[0013] The sensor 20 is configured to acquire the power generation state of the solar panel 10. The sensor 20 acquires at least the values ​​of the voltage V and current I output by the solar panel 10 as the power generation state of the solar panel 10. The sensor 20 may use detection elements such as a voltage sensor and a current sensor. The sensor 20 may be configured integrally with the solar panel 10, or may be configured as included in the solar power generation control device 40.

[0014] The DCDC converter 30 is a component for controlling the power generation of the solar panel 10. This DCDC converter 30 controls the power generation state (power point) of the solar panel 10 according to a voltage command value given from the solar power generation control device 40, and outputs the power obtained by the control. The output of the DCDC converter 30 is supplied to a battery, a load, etc. (not shown).

[0015] The solar power generation control device 40 is configured to control the operation of the DCDC converter 30 based on the power generation state of the solar panel 10 acquired by the sensor 20, thereby controlling the solar panel 10 to generate maximum power. This solar power generation control device 40 includes an MPPT control unit 41, which is a first control unit, a feedforward control unit 42, which is a second control unit, and a correction control unit 43, which is a third control unit.

[0016] The MPPT control unit 41 receives the detection value (V value) of the output voltage V of the solar panel 10 and the detection value (I value) of the output current I of the solar panel 10 from the sensor 20, and executes MPPT control to search for the maximum power point of the solar panel 10 under the current solar radiation conditions based on the output power P of the solar panel 10 obtained from the V value and the I value. A well-known technique called a hill climbing method can be used for the MPPT control of this embodiment. The MPPT control unit 41 outputs a voltage derived assuming that the solar panel 10 is capable of outputting maximum power as a control voltage Vmppt to the correction control unit 43 in a predetermined first period. The length of this first period is not particularly limited and may be set arbitrarily according to the performance required for the solar power generation system 1, etc.

[0017] The feedforward control unit 42 receives a detection value (I value) of the output current I of the solar panel 10 from the sensor 20, and executes feedforward control to derive a correction voltage Vff, which is a voltage for correcting the control voltage Vmppt derived by the MPPT control unit 41, based on the I value. More specifically, the feedforward control unit 42 derives the correction voltage Vff based on a voltage correction map prepared in advance. An example of the voltage correction map is shown in FIG. 2. In FIG. 2, for example, if the output current I of the solar panel 10 is "I1", "V1" is derived as the correction voltage Vff.

[0018] The voltage correction map of FIG. 2 can be created from the IV curve of the solar panel 10 according to the amount of solar radiation. 2 , 700W / m 2 , and 1000 W / m 2 3 shows an example of an IV curve when there is solar radiation of 200 W / m. As shown in FIG. 3, the optimum voltage (white circle in FIG. 3) corresponding to the maximum power point of the solar panel 10 changes depending on the amount of solar radiation, and the optimum voltage changes so as to become higher as the amount of solar radiation increases (dotted line in FIG. 3). In this embodiment, the correction voltage Vff is determined based on each voltage difference in the optimum voltage that varies depending on the change in the amount of solar radiation. As an example, 2 The optimum voltage for solar radiation is 35V, 700W / m 2 The optimum voltage for solar radiation is 38V and 1000W / m 2 If the optimum voltage for the solar radiation is 39V and the optimum voltage of "35V" is used as the standard for correction, then the 2 Correction voltage Vff during solar radiation is 0V, 700W / m 2 The correction voltage Vff during solar radiation is 3V (=38V-35V) and 1000W / m 2 It is possible to create a voltage correction map in which the correction voltage Vff during solar radiation is 4 V (=39 V-35 V). Note that the correction voltage Vff is not limited to a positive value and may be a negative value.

[0019] The feedforward control unit 42 outputs the correction voltage Vff derived based on the output current I of the solar panel 10 to the correction control unit 43. It is desirable that the correction voltage Vff is derived (updated) at a predetermined second cycle that is shorter than the first cycle of the MPPT control described above. This makes it possible to quickly respond to the latest solar radiation conditions of the solar panel 10. The length of the second cycle can be set arbitrarily depending on the response performance that the solar power generation control device 40 is to achieve. In addition, this second cycle may be a cycle in which the correction voltage Vff is output to the correction control unit 43, or a cycle in which the output current I of the solar panel 10 is obtained from the sensor 20.

[0020] The correction control unit 43 corrects the voltage derived by the MPPT control unit 41 with the voltage derived by the feedforward control unit 42, and controls the operation of the DCDC converter 30 using the corrected voltage as a command value. More specifically, the correction control unit 43 adds the correction voltage Vff derived by the feedforward control unit 42 to the control voltage Vmppt derived by the MPPT control unit 41, converts the voltage after the addition (Vmppt+Vff) into a signal in a format suitable for controlling the DCDC converter 30 (for example, a PWM signal applied to the gate of a transistor), and outputs it to the DCDC converter 30. The result of the control of the DCDC converter 30 by the correction control unit 43 is reflected in the output voltage V and output current I of the solar panel 10 and is fed back to the solar power generation control device 40.

[0021] The solar power generation control device 40 can typically be configured as an electronic control unit (ECU) including a processor such as a microcomputer, a memory, an input / output interface, etc. This electronic control unit can realize the functions of the MPPT control unit 41, the feedforward control unit 42, and the correction control unit 43 described above by the processor reading and executing a program stored in the memory.

[0022] [Control example] Furthermore, the control performed by the solar power generation control device 40 according to this embodiment will be described in an easy-to-understand manner with reference to Figs.

[0023] Fig. 4 is a diagram showing an example of a PV curve of the solar panel 10, to explain the control performed by the solar power generation control device 40 when the amount of solar radiation received by the solar panel 10 suddenly decreases. In Fig. 4, it is assumed that the amount of solar radiation suddenly decreases from a state in which the solar panel 10 is generating power at maximum power P1 due to a large amount of solar radiation (the voltage command value of the correction control unit 43 is "Vmppt+Vff1"), and the generated power of the solar panel 10 drops to P2.

[0024] In this case, in the conventional MPPT control, a steady hill-climbing search must be performed from the power P2 to the maximum power P4 under the current low amount of solar radiation. In contrast, in the control of the present embodiment, when the power generated by the solar panel 10 drops to the power P2, the correction voltage Vff1 is changed to a smaller correction voltage Vff2 (the correction amount is reduced) according to the output current I of the solar panel 10 that has decreased with this power drop. By this control, the voltage command value of the correction control unit 43 becomes "Vmppt+Vff2", and the start point where the MPPT control unit 41 performs the hill-climbing search is shifted (jumped) from the power P2 point to the point where the solar panel 10 can generate the power P3. Therefore, the time until the MPPT control unit 41 reaches the maximum power P4 can be significantly shortened compared to the conventional control.

[0025] Fig. 5 is a diagram showing an example of a PV curve of the solar panel 10, to explain the control performed by the solar power generation control device 40 when the amount of solar radiation received by the solar panel 10 suddenly increases. In Fig. 5, it is assumed that the amount of solar radiation suddenly increases from a state in which the solar panel 10 is generating power at maximum power P5 due to a small amount of solar radiation (the voltage command value of the correction control unit 43 is "Vmppt+Vff3"), and the generated power of the solar panel 10 rises to P6.

[0026] In this case, in the conventional MPPT control, a hill-climbing search must be performed step by step from the power P6 to the maximum power P8 under the current large amount of solar radiation. In contrast, in the control of the present embodiment, when the power generated by the solar panel 10 rises to the power P6, the correction voltage Vff3 is changed to a larger correction voltage Vff4 (the correction amount is increased) according to the output current I of the solar panel 10 that has increased with this power increase. By this control, the voltage command value of the correction control unit 43 becomes "Vmppt+Vff4", and the start point where the MPPT control unit 41 performs the hill-climbing search is shifted (jumped) from the power P6 to the point where the solar panel 10 can generate the power P7. Therefore, the time until the MPPT control unit 41 reaches the maximum power P8 can be significantly shortened compared to the conventional control.

[0027] <Actions and Effects> As described above, the solar power generation control device 40 according to one embodiment of the present disclosure includes an MPPT control unit 41 (first control unit) that derives a control voltage Vmppt through MPPT control based on the output power P(I, V) of the solar panel 10 to cause the solar panel 10 to generate maximum power, a feedforward control unit 42 (second control unit) that derives a correction voltage Vff for correcting the control voltage Vmppt based on the output current I of the solar panel 10, and a correction control unit 43 (third control unit) that controls the power generation of the solar panel 10 using the voltage obtained by adding the correction voltage Vff to the control voltage Vmppt as a command value.

[0028] According to this configuration, a part of the voltage command value instructed to the DC-DC converter 30 to make the solar panel 10 generate maximum power can be set as a correction value that can be changed according to the output current I of the solar panel 10 that quickly responds to changes in solar radiation. As a result, the control voltage Vmppt of the solar panel 10, whose maximum power point has shifted significantly due to a sudden change in solar radiation, can be shifted (jumped) to the vicinity of the maximum power point by the correction voltage Vff. Therefore, since the hill-climbing start point of the MPPT control approaches the maximum power point of the solar panel 10, the time until the maximum power point of the solar panel 10 is identified can be shortened compared to control that does not use the correction voltage Vff. Therefore, a decrease in the power generation efficiency of the solar panel 10 can be suppressed.

[0029] Furthermore, in the solar power generation control device 40 of this embodiment, by making the second period in which the feedforward control unit 42 derives the correction voltage Vff shorter than the first period in which the MPPT control unit 41 searches for the maximum power point of the solar panel 10, the control voltage Vmppt of the MPPT control can be brought closer to the maximum power point more quickly, so further time savings can be expected.

[0030] Furthermore, according to the solar power generation control device 40 of this embodiment, it is possible to grasp the change in the solar radiation of the solar panel 10 by monitoring the output current I of the solar panel 10. This makes it possible to easily solve the conventional problem that, when the current power generation power falls below the previous power generation power in the hill-climbing step of MPPT control, it is not possible to clearly determine whether the cause is a slight deviation from the maximum power point of the solar panel 10 or a large deviation due to a sudden change in solar radiation.

[0031] The above describes one embodiment of the present disclosure, but the present disclosure can be understood as a solar power generation control device, a solar power generation system equipped with a solar power generation control device, a method executed by a solar power generation control device, a program for executing the method, a computer-readable non-transitory recording medium storing the program, and a vehicle equipped with a solar power generation system including a solar power generation control device. [Industrial Applicability]

[0032] The solar power generation control device of the present disclosure can be used in solar power generation systems mounted on vehicles, etc. [Explanation of symbols]

[0033] 1. Solar power generation system 10. Solar Panels 20 Sensors 30 DC-DC Converter 40 Solar power generation control device 41 MPPT control unit 42 Feedforward control section 43 Correction control section

Claims

1. A solar power generation control device that controls power generation from a solar panel, A first control unit derives a control voltage for causing the solar panel to generate maximum power by MPPT control based on an output power of the solar panel; A second control unit that derives a correction voltage for correcting the control voltage based on an output current of the solar panel; A solar power generation control device comprising: a third control unit that controls power generation of the solar panel using a voltage obtained by correcting the control voltage with the correction voltage.

2. The solar power generation control device according to claim 1 , wherein the second control unit derives the correction voltage in a second period that is shorter than a first period in which the first control unit derives the control voltage.

3. The solar power generation control device according to claim 1 , wherein the second control unit derives a smaller correction voltage as the output current of the solar panel decreases.

4. The solar power generation control device according to any one of claims 1 to 3, wherein the second control unit derives the correction voltage using a map that correlates the output current and the correction voltage, the map being determined based on changes in the IV curve according to the solar radiation conditions of the solar panel.

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