JP2014235566A - Solar battery controller and solar battery control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar battery controller and a solar battery control method capable of improving follow-up performance as compared with a conventional technique in a case of exerting a solar battery maximum power point follow-up control in view of a change in solar radiation.SOLUTION: An output voltage and an output current of a solar battery 1 are detected and power generated by the solar battery 1 is calculated based on those detection values. On the other hand, solar radiation change detection means 8 detects a change in solar radiation on the basis of the detection values of the output voltage and the output current of the solar battery 1, voltage setting means 4 switches over between a setting of a target value V* of the output voltage using changes in generated power at two measuring points and a setting of a target value V* of the output voltage using changes in generated power at three measuring points depending on a detection result of the change in solar radiation, and voltage control means 5 controls the output voltage of the solar battery 1 via a power converter 6 so that the output voltage is equal to the target value V* of the output voltage switched and set.

Description

  The present invention relates to a solar cell control device and a solar cell control for searching and tracking an optimum operating voltage so that the solar cell operates at the maximum power point in order to extract maximum power from the solar cell in a solar power generation system. It is about the method.

  Since the output power (P) -output voltage (V) characteristic of the solar cell used in the photovoltaic power generation system is generally a mountain-shaped characteristic, the solar cell is operated at the top of the mountain-shaped, that is, at the maximum power point. If controlled, the power generated by the solar cell can always be effectively utilized to the maximum. Therefore, change the voltage and current at the operating point of the solar cell, detect the power change that accompanies it, search for the optimal operating voltage so that the solar cell always operates at the maximum power point, and follow-up control for tracking control Control (hereinafter referred to as MPPT control) has been proposed.

  As a technique for performing such MPPT control, for example, the direction in which the output voltage of the solar cell is changed is determined by increasing or decreasing (positive / negative) the change amount ΔP of the output power of the solar cell with respect to the change amount ΔV of the output voltage of the solar cell. There is so-called hill climbing control.

  By the way, the maximum power point of a solar cell varies depending on factors such as the amount of solar radiation and temperature. Therefore, the hill climbing control described above is an effective technique for searching for the maximum power point when factors such as the amount of solar radiation hardly change, but changes in the amount of solar radiation etc. occur during the search for the maximum power point based on hill climbing control. When this occurs, the maximum power point also fluctuates, so that the direction in which the output voltage of the solar cell is changed is incorrect, and a malfunction occurs that causes a large distance from the maximum power point.

  Therefore, in the prior art, the amount of change in the generated power is obtained by changing the output voltage, and then the amount of change in the generated power caused by the change in the amount of solar radiation while the output voltage is kept constant is obtained. Then, the output voltage is changed based on the amount of change in the generated power obtained when the output voltage is changed and the amount of change in the generated power due to the change in the amount of solar radiation obtained with the output voltage kept constant. A device that performs MPPT control by determining a direction has been proposed (for example, see Patent Document 1 below).

Japanese Patent No. 3516077

  Since the MPPT control based on the prior art described in Patent Document 1 takes into account the change in the amount of solar radiation, it is possible to suppress the occurrence of malfunction caused by the change in the amount of solar radiation as in hill climbing control. However, after measuring the amount of change in output power due to change in output voltage, it is necessary to ensure a period for measuring the amount of change in generated power due to change in solar radiation. For this reason, extra time is required to perform MPPT control, and the follow-up response performance is degraded.

  The present invention was made to solve the above problems, and a solar cell control device that improves the follow-up response performance in the case of performing MPPT control in consideration of changes in the amount of solar radiation than before, And it aims at providing a solar cell control method.

  A solar cell control device according to the present invention includes a power conversion device that converts DC power from a solar cell and supplies it to a load, a voltage detection device that detects an output voltage of the solar cell, and an output current of the solar cell. A current detection device to detect, voltage control means for controlling the output voltage of the solar cell via the power converter, and calculation of generated power based on detection values of the voltage detection device and the current detection device and the power generation Voltage setting means for setting a target value of the output voltage for the voltage control means so as to maximize the power, and a solar radiation amount for detecting a change in the solar radiation amount based on each detected value of the voltage detection device and the current detection device Change detection means, and the voltage setting means is configured to output an output voltage using a change in generated power at two measurement points according to a detection result of the change in solar radiation amount by the solar radiation amount change detection means. And setting the target value, it is characterized in that switching between setting the target value of the output voltage with a change in the generated power of 3 measurement points.

  Further, the solar cell control method according to the present invention provides an optimum operating voltage so that the solar cell operates at the maximum power point when DC power from the solar cell is converted into power by a power converter and supplied to a load. A solar cell control method for searching and tracking control, wherein each of the output voltage and output current of the solar cell is detected, and the generated power of the solar cell is calculated based on the detected values, A step of detecting a change in solar radiation based on each detected value of the output voltage and output current of the battery, and a target value of the output voltage using a change in generated power at two measurement points according to the detection result of the solar radiation quantity change And setting the target value of the output voltage using the change in the generated power at the three measurement points, and the power conversion device so as to be the target value of the output voltage that has been switched and set. Through is characterized by comprising a step of controlling the output voltage of the solar cell.

  According to the present invention, a change in solar radiation amount is detected based on the detected values of the output voltage and output current of the solar cell, and the change in generated power at two measurement points is detected according to the detection result when the solar radiation amount change is small. Is used to set the target value of the output voltage, and when the change in the amount of solar radiation is large, the target value of the output voltage is set using the change in the generated power at the three measurement points. That is, the setting of the target value of the output voltage using the change in the generated power at the two measurement points according to the change in the amount of solar radiation, and the setting of the target value of the output voltage using the change in the generated power at the three measurement points. Since switching is performed, the amount of solar radiation is lower than when only setting the target value of the output voltage using the change in generated power at three measurement points as in the past, while preventing the occurrence of malfunction due to changes in the amount of solar radiation. This makes it possible to improve the follow-up response performance when performing MPPT control in consideration of the change of the above-mentioned.

It is a block diagram which shows the structure of the solar cell control apparatus in Embodiment 1 of this invention. It is a block diagram which shows the structure of the solar radiation amount change detection means with which the solar cell control apparatus of Embodiment 1 of this invention is provided. It is a flowchart with which it uses for description of the MPPT control operation | movement in the solar cell control apparatus of Embodiment 1 of this invention. It is a characteristic view which shows the relationship between the MPPT control operation | movement based on the flowchart of FIG. 3, the output voltage of a solar cell, and output electric power. It is a timing chart explaining the MPPT control operation based on the flowchart of FIG. It is a flowchart with which it uses for description of other MPPT control operation | movement in the solar cell control apparatus of Embodiment 1 of this invention. It is a characteristic view which shows the relationship between the MPPT control operation | movement based on the flowchart of FIG. 6, the output voltage of a solar cell, and output electric power. It is a timing chart explaining the MPPT control operation based on the flowchart of FIG. It is a block diagram which shows the other structure of the solar radiation amount change detection means with which the solar cell control apparatus of Embodiment 1 of this invention is provided. It is explanatory drawing of the method of the setting of the judgment value by the judgment value setting means with which the solar radiation amount change detection means of FIG. 9 is provided. It is a block diagram which shows the structure of the solar cell control apparatus in Embodiment 2 of this invention.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a solar cell control device according to Embodiment 1 of the present invention, and FIG. 2 is a block diagram showing a configuration of solar radiation amount change detection means provided in the solar cell control device of FIG.

  The solar cell control device according to the first embodiment includes a power conversion device 6 that converts DC power from the solar cell 1 that generates solar power and supplies the converted power to the load 7 and detects the output voltage of the solar cell 1. Voltage detecting device 2 that detects the output current of the solar cell 1, voltage control means 5 that controls the output voltage of the solar cell 1 via the power converter 6, The voltage setting means 4 for setting the target value V * of the output voltage of the battery 1 and the solar radiation amount change detecting means 8 for detecting the solar radiation amount change based on the detection values of the voltage detection device 2 and the current detection device 3 are provided.

  A DC / DC converter using a switching device, a DC / AC inverter, or the like is applied to the power conversion device 6 described above, and the output voltage of the solar cell 1 or the power conversion device 6 is changed by changing the on / off duty ratio of the gate pulse. The output voltage, output frequency, etc. can be changed.

  The voltage control means 5 includes, for example, PI control means for controlling the difference between the output voltage target value V * from the voltage setting means 4 and the output voltage detected by the voltage detection device 2 to be zero, and this PI control. It comprises pulse generating means (all not shown) for generating a gate driving pulse in accordance with the output from the means. Thereby, the on / off duty of the switching device of the power converter 6 is controlled to control the output voltage of the solar cell 1.

  The voltage setting means 4 calculates the output power of the solar cell based on the detected values of the voltage detection device 2 and the current detection device 3, and operates so as to operate under an output voltage at which the output power of the solar cell 1 is maximized. A target value V * of the output voltage is set and output to the voltage control means 5.

  In this case, the setting of the output voltage target value V * by the voltage setting means 4 includes setting using the change in the generated power at the two measurement points and the change in the generated power at the three measurement points, as will be described in detail later. There are settings used. The voltage setting unit 4 sets the target value V * of the output voltage using the change in the generated power at the two measurement points and three measurement points according to the detection result of the solar radiation amount change by the solar radiation amount change detection unit 8. The setting of the target value V * of the output voltage using the change in the generated power is switched.

  Here, how to set the target value V * of the output voltage using the change in the generated power at the two measurement points and how to set the target value V * of the output voltage using the change in the generated power at the three measurement points will be described below. Explained.

  First, as a method for setting the target value V * of the output voltage using the generated power at the two measurement points in the voltage setting means 4, the output voltage is changed by increasing / decreasing (positive / negative) the amount of change in the generated power with respect to the voltages at two different operating points. There is a so-called hill-climbing method in which a target value V * is set. Hereinafter, this hill-climbing method is referred to as algorithm 0.

  Further, here, there are two methods for setting the target value V * of the output voltage using the power generated at the three measurement points in the voltage setting means 4.

  First, the output voltage target is determined by using the amount of change in generated power with respect to voltages at two different operating points and the amount of change in generated power due to changes in the amount of solar radiation after holding the output voltage for one period at one operating point. In this method, the value V * is set. Hereinafter, this method is referred to as algorithm 1.

Second, determine the generated power of the first operating voltage V _A and the second operating voltage V _B, then again determine the generated power of the first operating voltage V _A after a period of time, the first operating voltage V _A it is a method of setting the target value V * of the output voltage with a variation between the mean value of the generated power and the generated power of the second operating voltage V _B at. Hereinafter, this method is referred to as algorithm 2.

Since this algorithm 2 uses the average value of the generated power at the first operating voltage _VA , it acts as a kind of low-pass filter, and even if the change in solar radiation fluctuates in a short cycle, the influence of the fluctuation There is an advantage over Algorithm 1 in that the output voltage target value V * can be stably set.

  The solar radiation amount change detection means 8 detects the solar radiation amount change by calculating the solar radiation amount change value based on the detection values of the voltage detection device 2 and the current detection device 3, and determines the magnitude thereof. Output to the voltage setting means 4. Then, the voltage setting means 4 sets the output voltage target value V * based on the algorithm 0 and the output voltage target value V * based on the algorithm 1 or 2 according to the determination result. And switch.

FIG. 2 is a block diagram showing the configuration of the above-described solar radiation amount change detecting means 8.
The solar radiation amount change detection means 8 includes a solar radiation amount change value calculation means 81 for calculating the solar radiation amount change value, and a predetermined determination value (fixed value) for the solar radiation amount change value calculated by the solar radiation amount change value calculation means 81. ) The solar radiation amount change judging means 82 for judging the magnitude of the solar radiation amount change as compared with P _TH 0 and P _TH 1.

  The solar radiation amount change value calculation means 81 obtains the generated power value based on, for example, the voltage value detected by the voltage detection device 2 and the current value detected by the current detection device 3, and calculates the voltage differential value of the generated power value as the current value. The value normalized in step 1 is obtained as the solar radiation amount change value dR. That is, the solar radiation amount change value calculating means 81 obtains the solar radiation amount change value dR as in the following equation (1).

  Thus, since the solar radiation amount change value dR is calculated from the output voltage and output current of the solar cell 1 detected by the voltage detection device 2 and the current detection device 3, and the calculated generated power, the solar radiation amount change is detected in real time. It is possible to select a method for setting the target value V * of the output voltage in accordance with the change in the amount of solar radiation.

The solar radiation amount change determination unit 82 compares the solar radiation amount change value dR calculated by the solar radiation amount change value calculation unit 81 with two predetermined determination values (fixed values) P _TH 0 and P _TH 1 and the solar radiation amount. Determine the magnitude of the change and output the determination result to the voltage setting means 4

  In addition, since the output current of the solar cell 1 changes greatly with a change in the amount of solar radiation, the solar radiation amount change value calculation means 81 is detected by, for example, the voltage detection device 2 instead of using the above equation (1). Based on the voltage value and the current value detected by the current detection device 3, the voltage differential value of the current value can be obtained as the solar radiation amount change value dR. That is, the solar radiation amount change value calculating means 81 may obtain the solar radiation amount change value dR as in the following equation (2).

  Thus, even if it is the method of calculating the solar radiation amount change value dR based on Formula (2), the solar radiation amount change can be detected in real time by a simpler method than Formula (1).

  Next, regarding the processing operation when the voltage setting means 4 determines the target value V * of the output voltage based on the above algorithm 0 and algorithm 1, the flowchart shown in FIG. 3 and the voltage-power characteristic diagram shown in FIG. This will be described with reference to the time chart shown in FIG. For convenience of explanation, the case where the change in the solar radiation amount is large from time t0 to time t2 and the MPPT control is performed under a stable condition with little change in the solar radiation amount after time t2 is illustrated. It is not limited to such a case.

In order to search and track the optimum operating voltage so that the solar cell 1 operates at the maximum power point, first, a certain operating voltage V ₀ is set in the voltage setting means 4 (step S1). Then, under this operating voltage V _0, the voltage detector 2 and detects the output voltage V ₀ and the output current I ₀ of the solar cell 1 by a current detection unit 3, and output the output voltage V ₀ detected current I ₀ The generated power P ₀ of the solar cell 1 is obtained from the product of (Step S2).

Next, the operating voltage V ₁ obtained by changing the current output voltage V ₀ by V _step (for example, about 1 V) is set (step S3). Then, the output voltage V ₁ and the output current I ₁ under the operating voltage V ₁ are detected, and the generated power P ₁ is obtained from the product of the detected output voltage V ₁ and the output current I ₁ (step S4).

On the other hand, the solar radiation amount change value calculation means 81 calculates the solar radiation amount change value from the output voltage, output current, and calculated generated power detected in step S2 or step S4 based on the above-described formula (1) or formula (2). dR is obtained (step S5). Next, the solar radiation amount change determining means 82 compares the solar radiation amount change value dR calculated by the solar radiation amount change value calculating means 81 with two preset determination values P _TH 0 and P _TH 1, and It is determined whether or not the relationship (3) holds (step S6).

  When the expression (3) is satisfied, the solar radiation amount change determining unit 82 determines that the solar radiation amount change is small. Accordingly, the voltage setting unit 4 generates the power generated by the two measurement points based on the algorithm 0. The target value V * of the used output voltage is set.

That is, the power change amount dP (= P ₁ −P ₀ ) of the output power with respect to the change amount V _step (= V ₁ −V ₀ ) of the output voltage from the output voltage detected in step S2 and step S4 and the calculated generated power. The dPdV value indicating the increase / decrease is calculated as in the following equation (4) (step S7).

Next, it is determined whether or not dPdV <0 with respect to the dPdV value obtained by the above equation (4) (step S8). If so, the next change direction and change width of the output voltage are expressed as V _step = −. and dV (step S9), and also, if it is dPdV ≧ 0 substitutes the change direction and variation width of the next output voltage to the _V step = + and dV (step S10), and the value of _{V 1 V 0,} the value of P ₁ is substituted into _{P 0} (step S11). Therefore, V ₀ changed to the value of V ₁ is set as a new target value V * of the output voltage. And it returns to step S3 and repeats the process after step S3.

  On the other hand, if the expression (3) does not hold in step S6, the solar radiation amount change determining unit 82 determines that the solar radiation amount change is large, and accordingly, the voltage setting unit 4 is based on the algorithm 1. Then, the target value V * of the output voltage using the generated power at the three measurement points is set.

That is, in order to estimate the power change due to insolation changes, the output voltage due to insolation changes after a certain period of time (e.g., 0.1 seconds to 1 second) has elapsed without changing the voltages V ₁ set in step S4 V ₁ and the output current I ₂ are detected, and the generated power P ₂ is obtained from the product of the detected output voltage V ₁ and the output current I ₂ (step S12). Then, the power change amount dP (= P ₂ −P ₁ ) accompanying the change in the amount of solar radiation in this case is calculated (step S13).

Next, the generated power P ₀ ′ (= P ₀ + dP) obtained by correcting the generated power P ₀ calculated in step S2 by dP is obtained (step S14). This corresponds to determining the generated power in consideration of changes in the amount of solar radiation under the first output voltage V ₀ . Subsequently, using the output voltage V ₁ detected in step S4, the calculated generated power P ₁ , and the corrected generated power P ₀ ′ calculated in step S14, the dPdV value is calculated using the above equation (4), It is obtained as dPdV = (P ₁ −P ₀ ′) / (V ₁ −V ₀ ) (step S15).

Since the generated power of the solar cell 1 has shifted from P ₀ to P ₂ at this time, the generated power P ₂ obtained in step 12 is next determined in determining the direction in which the output voltage target value V * is to be changed. after the value obtained by substituting the _{P 1} (step S16), and the process proceeds step S8 continue subsequent processing step S8. Accordingly, also in this case, in step S11, V ₀ changed to the value of V ₁ is set as a new target value V * of the output voltage.

  In FIG. 5, MPPT control is performed based on Algorithm 1 from time t0 to time t2 when the amount of solar radiation changes greatly. Therefore, in each stage when the target value V * of the output voltage is set sequentially in stages. Although the set cycle is longer than that in the case of algorithm 0, MPPT control is performed based on algorithm 0 after time t2 when the change in the amount of solar radiation becomes small and stable, so at each stage of the target value V * of the output voltage. The setting cycle is shortened.

  In this way, when the change in the amount of solar radiation changes from a large state to a small and stable state, the MPPT control is performed by switching from the algorithm 1 to the algorithm 0. Therefore, the target value V * of the output voltage can be set only by the algorithm 0. It is possible to improve the follow-up response performance when performing the MPPT control, compared to the case where the target value V * of the output voltage is set only by the algorithm 1, while preventing malfunction due to the change in the amount of solar radiation when performing the operation. It becomes.

  Next, regarding the processing operation when the voltage setting means 4 determines the target value V * of the output voltage based on the above algorithm 0 and algorithm 2, the flowchart shown in FIG. 6 and the voltage-power characteristic diagram shown in FIG. This will be described with reference to the time chart shown in FIG. For convenience of explanation, the case where the change in the solar radiation amount is large from time t0 to time t2 and the MPPT control is performed under a stable condition with little change in the solar radiation amount after time t2 is illustrated. It is not limited to such a case.

In order to search and control the optimum operating voltage so that the solar cell 1 operates at the maximum power point, the operating voltage V ₀ is first set to the first set voltage V _A in the voltage setting means 4 (step S1). ). Then, under this operating voltage V _{0 (=} V _A), and detects the output current I ₀ and the output voltage V ₀ which the solar cell 1 by the voltage detector 2 and the current detecting device 3, the detected output voltage V ₀ And the output current I ₀ , the generated power P ₀ of the solar cell 1 is obtained (step S 2).

Next, to set the operation voltages _{V 1} obtained by changing the current output voltage _{V 0 V step} (e.g., about 1V) by a second operating voltage _{V B} (step S3). Then, the output voltage V ₁ and the output current I ₁ under the operating voltage V ₁ (= V _B ) are detected, and the generated power P ₁ is obtained from the product of the detected output voltage V ₁ and the output current I ₁ (step) S4).

The solar radiation amount change value calculation means 81 calculates the solar radiation amount change value dR from the output voltage, output current, and calculated generated power detected in step S2 or step S4 based on the above-described equation (1) or equation (2). Obtained (step S5). Next, the solar radiation amount change determination means 82 compares the solar radiation amount change value dR calculated by the solar radiation amount change value calculation means 81 with the two predetermined determination values P _TH 0 and P _TH 1, and calculates the above-mentioned formula. It is determined whether or not the relationship (3) holds (step S6).

  When the expression (3) is satisfied, the solar radiation amount change determining unit 82 determines that the solar radiation amount change is small. Accordingly, the voltage setting unit 4 generates the power generated by the two measurement points based on the algorithm 0. The target value V * of the used output voltage is set.

That is, the power change amount dP (= P ₁ −P ₀ ) of the output power with respect to the change amount V _step (= V ₁ −V ₀ ) of the output voltage from the output voltage detected in step S2 and step S4 and the calculated generated power. The dPdV value indicating the increase / decrease is calculated based on the aforementioned equation (4) (step S7).

Next, it is determined whether or not dPdV <0 with respect to the dPdV value obtained by the above equation (4) (step S8). If so, the next change direction and change width of the output voltage are expressed as V _step = −. and dV (step S9), and also, if it is dPdV ≧ 0 substitutes the change direction and variation width of the next output voltage to the _V step = + and dV (step S10), and the value of _{V 1 V 0,} the value of P ₁ is substituted into _{P 0} (step S11).

Then, the first set voltage V _A and the second set voltage V _B are changed by V _step (step S20). Therefore, the changed first set voltage V _A is set as a new target value V * of the output voltage. And it returns to step S3 and repeats the process after step S3.

  On the other hand, if the expression (3) does not hold in step S6, the solar radiation amount change determining unit 82 determines that the solar radiation amount change is large, and accordingly, the voltage setting unit 4 is based on the algorithm 2. Then, the target value V * of the output voltage using the generated power at the three measurement points is set.

That is, in order to estimate the power change due to the change in the amount of solar radiation, the first operating voltage is set to the first set voltage V _A (= V ₀ ) set in the previous step S2 (step 31), and this first setting is made. Under the voltage V _A (= V ₀ ), the output voltage V ₀ and the output current I ₂ after a lapse of a certain period (for example, about 0.1 second to 1 second) are detected, and the detected output voltage V ₀ Request generated power _{P 2} from the product of the output current _{I 2} (step S32).

Next, the generated power PB under the second set voltage _{V B,} substituting generated power _{P 1} obtained in the previous step 4 (step S33). Further, as the generated power P _A under the first set voltage V _A , the average value (= (P ₂ + P ₀ ) of the generated power P ₀ obtained in step S2 and the generated power P ₂ obtained in step S32. ) / 2) is obtained (step S34). This is under the first output voltage V _A, which corresponds to determining the generated power P _A in consideration of solar radiation changes.

Subsequently, a power change amount dP (= P _B −P _A ) accompanying a change in the amount of solar radiation between the first set voltage V _A and the second set voltage V _B is calculated (step S35). Next, it is determined whether or not dP> 0 for the above dP value (step S36). If so, the next output voltage change direction and change width are set to V _step = −dV (step S37). When dP ≦ 0, the next change direction and change width of the output voltage are set to V _step = + dV (step S38).

Then, the first set voltage V _A and the second set voltage V _B are changed by V _step (step S39). Therefore, the changed first set voltage V _A is set as a new target value V * of the output voltage. And it returns to step S1 and repeats the process after step S1.

  In FIG. 8, MPPT control is performed based on Algorithm 2 from time t0 to time t2 when the amount of solar radiation changes greatly. Therefore, in each stage when the target value V * of the output voltage is set sequentially in stages. Although the setting cycle is longer than in the case of algorithm 0, MPPT control is performed based on algorithm 0 after time t2 when the amount of solar radiation is reduced and stabilized, so the output voltage target value V * is set at each stage. The cycle is shortened.

  In this way, when the change in the amount of solar radiation changes from a large state to a small and stable state, the MPPT control is performed by switching from the algorithm 2 to the algorithm 0. Therefore, the target value V * of the output voltage can be set only by the algorithm 0. It is possible to improve the follow-up response performance when performing the MPPT control compared to the case where the target value V * of the output voltage is set only by the algorithm 2 while preventing the malfunction caused by the change in the amount of solar radiation when performing it. It becomes.

  In addition, the solar radiation amount change detection means 8 in this Embodiment 1 is not restricted to the structure shown in FIG. 2, For example, the thing as shown in FIG. 9 may be used.

  That is, the solar radiation amount change detection means 8 having the configuration shown in FIG. 9 includes the voltage detection device 2 and the current detection device 3 in addition to the solar radiation amount change value calculation means 81 and the solar radiation amount change determination means 82 shown in FIG. A determination value setting unit 83 is provided for setting a determination value based on each detected value and output power calculated from each detected value.

In this case, for example, as shown in FIG. 10, the determination value setting means 83 is a voltage change between two measurement points where the output voltage is near zero volts in the output voltage-output power characteristic of the solar cell 1 when the amount of solar radiation is small. A change in generated power due to ΔV is set as one determination value P _TH 0, and a change in generated power due to a voltage change ΔV between two measurement points near the open circuit voltage of the solar cell 1 is set as the other determination value P _TH 1. , To calculate.

As described above, if the determination values P _TH 0 and P _TH 1 are calculated and set from the characteristics of the solar cell 1, the characteristics of the individual solar cells 1 are examined in advance and each determination value is manually set. Compared to the case, a determination value suitable for the characteristics of the solar cell 1 can be automatically set, which is convenient.

Then, the solar radiation amount change determination means 82 compares the solar radiation amount change value dR calculated by the solar radiation amount change value calculation means 81 with the determination values P _TH 0 and P _TH 1 set by the determination value setting means 83. It is determined whether or not the above equation (3) holds.

Embodiment 2. FIG.
FIG. 11 is a block diagram showing a configuration of a solar cell control apparatus according to Embodiment 2 of the present invention, and the same reference numerals are given to the same or corresponding components as those in Embodiment 1 shown in FIG.

  The feature of the second embodiment is that a solar cell characteristic table 9 is provided in place of the solar radiation amount change detecting means 8 of the first embodiment.

  In the solar cell characteristic table 9, the relationship between the solar radiation amount change values dR corresponding to combinations of the detection values of the voltage detection device 2 and the current detection device 3 is set in advance. That is, based on the output voltage and output current detected by the voltage detection device 2 and the current detection device 3, respectively, and the generated power calculated from these output voltage and output current, the above-described formula (1) or formula (2) The value of dR obtained in (1) is registered in advance. When the detection values of the voltage detection device 2 and the current detection device 3 are input, the solar radiation characteristic change value dR corresponding to the combination of these detection values is read from the solar cell characteristic table 9 and the voltage is read. The setting means 4 is provided.

  Therefore, the processing flow of the solar cell control device in the second embodiment is equivalent to the flowchart shown in FIG. 3 or FIG. 6, but the output voltage detected in step S2 and step S4 in FIG. 3 or FIG. When the generated power calculated from the output current and the detected values is determined, the solar radiation amount change value dR is obtained using the solar cell characteristic table 9 based on the combination of these values.

Thus, according to the second embodiment, since the solar radiation amount change value dR is determined using the solar cell characteristic table 9, the solar radiation amount change value dR is expressed by the equation (1) or the equation based on the output voltage and the output current. There is no need to calculate using (2). For this reason, the solar radiation amount change value dR can be quickly determined.
Since other configurations and operational effects are the same as those in the first embodiment, detailed description thereof is omitted here.

  Note that the present invention is not limited to the configurations of the first and second embodiments described above, and modifications may be made to each configuration or a part of the configuration may be omitted without departing from the spirit of the present invention. In addition, it is possible to combine the first and second embodiments.

1 solar cell, 2 voltage detector, 3 current detector, 4 voltage setting means,
5 voltage control means, 6 power converter, 7 load, 8 solar radiation amount change detection means,
9 solar cell characteristic table, 81 solar radiation amount change value calculating means,
82 solar radiation amount change determination means, 83 determination value setting means.

Claims (9)

A power conversion device that converts DC power from a solar cell and supplies it to a load, a voltage detection device that detects an output voltage of the solar cell, a current detection device that detects an output current of the solar cell, and the power conversion Voltage control means for controlling the output voltage of the solar cell via the device, and the voltage control so as to calculate the generated power based on the detection values of the voltage detection device and the current detection device and maximize the generated power Voltage setting means for setting a target value of the output voltage for the means, and a solar radiation amount change detecting means for detecting a solar radiation amount change based on each detection value of the voltage detection device and the current detection device,
The voltage setting means sets the target value of the output voltage using the change in the generated power at the two measurement points and sets the generated power at the three measurement points according to the detection result of the change in the solar radiation amount by the solar radiation amount change detecting means. A solar cell control device that switches between setting of a target value of an output voltage using change. The setting of the target value of the output voltage of the solar cell using the change in the generated power at the two measurement points is to set the target value by increasing or decreasing the amount of change in the generated power with respect to the voltage at two different operating points. The solar cell control apparatus according to 1. The setting of the target value of the output voltage of the solar cell using the change in the generated power at the three measurement points described above is the amount of change in the generated power with respect to the voltage at two different operating points, and the output voltage is held at one operating point for a certain period. The solar cell control device according to claim 1 or 2, wherein the target value is set using a change amount of the generated power due to a later change in the amount of solar radiation. The setting of the target value of the output voltage of the solar cell using the change in the generated power at the three measurement points is obtained by calculating the generated power of the first operating voltage and the second operating voltage, and after a certain period of time, the first operating voltage The target value is set using the average value of the generated power at the first operating voltage and the amount of change in the generated power at the second operating voltage. The solar cell control apparatus according to claim 2. The solar radiation amount change detecting means obtains a generated power value based on the voltage value detected by the voltage detecting device and the current value detected by the current detecting device, and calculates a voltage differential value of the generated power value as the current. A solar radiation amount change value calculating means that calculates a value normalized by the value as a solar radiation amount change value; and the solar radiation amount change value calculated by the solar radiation amount change value calculation means and a predetermined determination value. The solar cell control device according to any one of claims 1 to 4, further comprising a solar radiation amount change determination unit that determines the magnitude of the amount change. The solar radiation amount change detection means calculates the solar radiation amount change value as a solar radiation amount change value based on the voltage value detected by the voltage detection device and the current value detected by the current detection device. An amount change value calculating means; and an amount change determination means for determining an amount of change in the amount of insolation based on a change value of the amount of insolation calculated by the amount of change in solar radiation value calculation means and a preset determination value. The solar cell control device according to any one of claims 1 to 4. The solar radiation amount change detection means includes a determination value setting means for setting the determination value based on each detection value of the voltage detection device and the current detection device, and output power calculated from each detection value. The solar cell control device according to claim 5 or 6, wherein: In place of the solar radiation amount change detecting means, a solar cell characteristic table in which the relationship between the solar radiation amount change values corresponding to the detected values of the voltage detection device and the current detection device is set in advance is provided. 2. The solar radiation amount change value corresponding to a combination of each detected value based on each detected value of the current detecting device is read from the solar cell characteristic table and given to the voltage setting means. Solar cell control device. This is a solar cell control method for searching and tracking the optimum operating voltage so that the solar cell operates at the maximum power point when DC power from the solar cell is converted by the power converter and supplied to the load. And
Detecting the output voltage and output current of the solar cell, respectively, and calculating the generated power of the solar cell based on the detected values;
Detecting a change in solar radiation based on each detected value of the output voltage and output current of the solar cell;
In accordance with the detection result of the solar radiation amount change, setting of a target value of output voltage using a change in generated power at two measurement points, and setting of a target value of output voltage using a change in generated power at three measurement points; A step of switching between
Controlling the output voltage of the solar cell via the power converter so as to be the target value of the output voltage set to be switched,
The solar cell control method characterized by including.

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