Power conversion device and control method thereof

Abstract

To provide a photovoltaic power generation system which is smaller in circuit scale than an MPPT (Maximum Power Point Tracking), can be realized at a low cost, and can always take in maximum power from a solar cell panel.SOLUTION: The power converter includes a voltage control circuit 10 for controlling an input voltage from a solar battery 1 to a predetermined output voltage by using a maximum power control method for holding an operating point of a maximum operating voltage at which a power generation amount of the solar battery 1 becomes maximum. The power converter further includes a memory 25 for previously measuring and storing the maximum operating voltage with respect to the illuminance to the solar cell 1 and the temperature in the vicinity of the solar cell 1, an illuminance sensor 12 for detecting the illuminance to the solar cell 1, and a temperature sensor 13 for detecting the temperature in the vicinity of the solar cell 1. The control circuit retrieves the maximum operating voltage stored in the memory 25 based on the detected illuminance and the detected temperature, sets the retrieved maximum operating voltage, and controls the input voltage from the solar battery 1 by using the maximum power control method.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power conversion device such as a DC / DC converter for controlling the output voltage or output current of a solar cell such as a solar panel, and a control method thereof. [Background technology]

[0002] The intensity of sunlight varies widely, ranging from several hundred to tens of thousands of lux, depending on weather conditions, time, and installation location (indoors, near a window, in the shade, or in full sun). Furthermore, as shown in Figures 9 to 11, solar panels have a maximum operating power point, and the voltage at this maximum operating power point (maximum operating voltage) varies depending on the illuminance and temperature. Therefore, in order to efficiently extract power from the solar panel and store it in a secondary battery, etc., it is necessary to control the output of the solar panel to the optimal voltage (maximum operating voltage) according to the operating environment. There are two control methods for this: MPPT (maximum power point tracking) and MPPC (maximum power point control).

[0003] As is clear from the characteristics in Figure 9, there is a maximum operating voltage at which maximum power is obtained. It is generally said that the maximum operating voltage exists at approximately 80% of the open-circuit voltage, and a method of conveniently drawing power at 80% of the open-circuit voltage is known. As is clear from the characteristics in Figure 10, as the irradiance increases, the open-circuit voltage increases almost proportionally. As is clear from the characteristics in Figure 11, as the temperature increases, the open-circuit voltage decreases almost inversely proportionally.

[0004] MPPT is an abbreviation for Maximum Power Point Tracking, and is a method of adjusting the input voltage while tracking the maximum power point, which fluctuates due to changes in weather conditions, etc., and is commonly known as the "hill climbing method" (see, for example, Patent Documents 1 and 2).

[0005] MPPC is an abbreviation for Maximum Power Point Control, and the maximum operating voltage is set for each code (product model number) of the IC chip of the DC / DC converter, and by controlling the voltage of the solar panel around the predetermined maximum operating voltage Vmp, power can be transferred to the secondary side at the maximum power generation amount (see, for example, Non-Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-259762 [Patent Document 2] Japanese Patent Application Publication No. 6-083465 [Non-patent literature]

[0007] [Non-Patent Document 1] Nisshinbo Microdevices, "What is the MPPC function?", [online], April 1, 1998, [Retrieved June 18, 2024], Internet,<URL:https: / / www.nisshinbo-microdevices.co.jp / ja / faq / 085.html> [Non-patent document 2] Nisshinbo Microdevices, "R1800 Series Low Current Consumption (IQ144nA) Step-Down DC / DC Converter for Energy Harvesting," Datasheet, [Retrieved June 18, 2024], Internet, <URL:https: / / www.nisshinbo-microdevices.co.jp / ja / products / dc-dc-switching-regulator / spec / ?product=r1800> Summary of the Invention [Problem to be solved by the invention]

[0008] MPPT is a method that monitors and calculates the output voltage and output current from solar panels, and then changes and tracks these voltages and currents to ensure that the solar panels are always at their maximum power point. This requires microcontroller control. Furthermore, with this type of circuit, attempting to monitor and calculate at high speed places a heavy load on the microcontroller, resulting in increased energy consumption. Performing the monitoring and calculations at low speeds takes time to find the maximum power point, ultimately reducing power generation efficiency. Therefore, unless a certain level of solar cell system (medium-sized or larger) is used, the overall power generation efficiency does not improve, leading to higher costs. Furthermore, with this method, increasing the speed requires more complex circuits, calculation algorithms, and correction programs, which also contributes to higher costs.

[0009] On the other hand, MPPCs have a fixed maximum power point voltage based on the IC chip code (product model number), so they cannot be dynamically changed based on illuminance. As a result, when a DC / DC converter with a high maximum power point voltage is operated in a low-illuminance environment, it is unable to take in power, and when a DC / DC converter with a low maximum power point voltage is operated in a high-illuminance environment, it can take in power but loses a lot of it. This means that while MPPCs are effective for indoor use where there is little change in illuminance, they cannot take in power effectively for outdoor use.

[0010] The object of the present invention is to solve the above problems and to provide a power conversion device and a control method thereof that can be realized at a lower cost and with a smaller circuit scale than MPPT, and that can always draw maximum power from a solar panel. [Means for solving the problem]

[0011] A power conversion device according to one aspect of the present disclosure includes: A power conversion device including a control circuit that controls an input voltage from a solar cell to a predetermined output voltage using a maximum power control method that maintains an operating point of a maximum operating voltage at which the amount of power generated by the solar cell is maximized, a first storage unit that pre-measures and stores a maximum operating voltage for an illuminance on the solar cell and a temperature in the vicinity of the solar cell; an illuminance sensor that detects illuminance on the solar cell; a temperature sensor for detecting a temperature in the vicinity of the solar cell; The control circuit searches for a maximum operating voltage stored in the first memory unit based on the detected illuminance and the detected temperature, sets the searched maximum operating voltage, and controls the input voltage from the solar cell using the maximum power control method. [Effects of the Invention]

[0012] Therefore, in a power conversion device according to an embodiment of the present disclosure, the control circuit searches for a maximum operating voltage stored in the first memory unit based on the detected illuminance and the detected temperature, sets the searched maximum operating voltage, and controls the input voltage from the solar cell using the maximum power control method. This allows for a circuit that is smaller in scale and lower in cost than MPPT, and can constantly draw maximum power from the solar cell panel. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a circuit diagram showing an example of the configuration of a DC / DC converter 100 according to an embodiment. [Figure 2] 2 is a circuit diagram showing a detailed configuration example of a maximum operating voltage tracking circuit 14 of FIG. 1. FIG. [Figure 3] 3 is a timing chart showing an example of a read signal Sread and an update signal Supdate in FIG. 2; [Figure 4] 3 is a circuit diagram showing an example of the configuration of a preparation circuit 200 that generates mapping data to be written into the memory 25 of FIG. 2. FIG. [Figure 5] 3 is a table showing an example of mapping data stored in the memory 25 of FIG. 2. [Figure 6]2 is a time series graph of the input voltage Vin, the output voltage Vfb, the comparison result signals V16 and V17 of the comparison circuits 16 and 17, and the gate control voltage Vg of the voltage control circuit 10, illustrating an example of the operation of MPPC (maximum power point control) executed by the DC / DC converter 100 of FIG. [Figure 7] 2 is a graph showing voltage-power characteristics in Case 1 of the DC / DC converter 100 according to the embodiment of FIG. 1. [Figure 8] 10 is a graph showing voltage-power characteristics in Case 2 of the DC / DC converter 100 of FIG. 1 according to an embodiment. [Figure 9] 10 is a graph showing characteristics of current density and power density relative to voltage in a solar cell panel according to a conventional example. [Figure 10] 10 is a graph showing characteristics of open-circuit voltage with respect to irradiance in a solar cell panel according to a conventional example. [Figure 11] 10 is a graph showing characteristics of open-circuit voltage with respect to temperature in a solar cell panel according to a conventional example. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments and modifications of the present invention will be described with reference to the drawings, in which the same or similar components are designated by the same reference numerals.

[0015] (Embodiment) Fig. 1 is a circuit diagram showing an example configuration of a DC / DC converter 100 according to an embodiment. In Fig. 1, an input voltage Vin from a solar cell 1, such as a solar panel, is input to circuits 10, 11, 14, 16, and 17 of the DC / DC converter 100 via an input capacitor Cin. Here, the DC / DC converter 100 is an example of a power conversion device, and is formed, for example, by a single-chip IC.

[0016] 1, DC / DC converter 100 includes a voltage control circuit 10, a reference voltage generation circuit 11, an illuminance sensor 12, a temperature sensor 13, a maximum operating voltage tracking circuit 14, an output voltage setting circuit 15, comparison circuits 16 and 17, an N-channel MOS transistor Q1, and a backflow prevention diode D1. Note that illuminance sensor 12 and temperature sensor 13 are provided near the installation position of solar cell 1, such as a solar panel.

[0017] The output voltage Vout from the DC / DC converter 100 is output to the load 3 via the inductor 2 and the output capacitor Cout, and here, the output voltage at the output terminal of the inductor 2 is fed back to the comparator circuit 17 as a feedback voltage Vfb. Note that, as a power supply voltage to the illuminance sensor 12 and the temperature sensor 13, the detection power supply voltage Vsens is supplied from the N-channel MOS transistor Q2 in Fig. 2 at the detection timing.

[0018] At the detection timing when a predetermined detection power supply voltage Vsens is supplied, the illuminance sensor 12 outputs an illuminance detection voltage Vl corresponding to the detected illuminance to the maximum operating voltage tracking circuit 14, and the temperature sensor 13 outputs a temperature detection voltage Vt corresponding to the detected temperature to the maximum operating voltage tracking circuit 14. The reference voltage generation circuit 11 generates a predetermined reference voltage Vref based on the input voltage Vin and outputs it as a reference voltage for the maximum operating voltage tracking circuit 14 and the output voltage setting circuit 15. The maximum operating voltage tracking circuit 14 is configured as shown in Figure 2 (described later), and generates a maximum operating voltage setting value Vmps (a setting value corresponding to the maximum operating voltage Vmp of the solar cell 1) using the input voltage Vin and the reference voltage Vref based on the illuminance detection voltage Vl and the temperature detection voltage Vt, and outputs it to the comparison circuit 16. The output voltage setting circuit 15 generates an output setting voltage Vos based on the reference voltage Vref and a setting fixed for each IC chip code (product model number), and outputs it to the comparison circuit 17. Each of the comparison circuits 16 and 17 has a predetermined hysteresis characteristic and operates as follows: Comparison circuit 16 compares input voltage Vin with maximum operating voltage setting value Vmps to generate a comparison result signal V16, which is output to voltage control circuit 10. Furthermore, comparison circuit 17 compares input voltage Vfb with output setting voltage Vos to generate a comparison result signal V17, which is output to voltage control circuit 10. Based on the input comparison result signals V16 and V17, voltage control circuit 10 generates a gate control voltage Vg for controlling the voltage flowing through MOS transistor Q1 and applies it to the gate of MOS transistor Q1.

[0019] In the DC / DC converter 100 configured as described above, the maximum operating voltage tracking circuit 14 tracks the illuminance value from the illuminance sensor 12 and the temperature value from the temperature sensor 13, setting the maximum operating voltage to the input voltage value (maximum operating voltage at the illuminance value and temperature value) corresponding to the illuminance value and temperature value, and the voltage control circuit 10 adjusts the output voltage by controlling the current from the solar cell 1 based on the set maximum operating voltage and output setting voltage.

[0020] Fig. 2 is a circuit diagram showing a detailed configuration example of the maximum operating voltage tracking circuit 14 in Fig. 1. In Fig. 2, the circuit is configured to include a timing generation circuit 20, voltage conversion and amplification circuits 21 and 22, AD converters 23 and 24, a memory 25 such as an OTPROM (One Time Programmable Read Only Memory), a delay flip-flop 26, a DA converter 27, and an N-channel MOS transistor Q2.

[0021] 2, voltage conversion and amplification circuit 21 amplifies the input illuminance detection voltage Vl to convert it to a predetermined voltage and outputs it to AD converter 23. Also, voltage conversion and amplification circuit 22 amplifies the input temperature detection voltage Vt to convert it to a predetermined voltage and outputs it to AD converter 24. AD converter 23 converts the input voltage into, for example, 5-bit digital data and outputs it to an address bus (upper 5 bits) of memory 25. Also, AD converter 24 converts the input voltage into, for example, 3-bit digital data and outputs it to an address bus (lower 3 bits) of memory 25.

[0022] FIG. 3 is a timing chart showing an example of the read signal Sread and the update signal Supdate in FIG.

[0023] The read signal Sread and update signal Supdate generated by the timing generation circuit 20 are generated by writing timing setting data from an external controller to a memory 20m, such as an OTPROM, within the timing generation circuit 20 via an interface 28, and the timing generation circuit 20 generates the read signal Sread and update signal Supdate based on the timing setting data. As shown in FIG. 3 , the timing generation circuit 20 generates a read signal Sread, for example, at an H level, at a predetermined first period T1 and outputs it to the output enable terminal of the memory 25 and the gate of the MOS transistor Q2, thereby turning on the MOS transistor Q2 and supplying the detection power supply voltage Vsens to the illuminance sensor 12 and the temperature sensor 13, thereby activating them. Furthermore, data previously stored in the memory 25 is output to a delay flip-flop 26, as will be described later. The timing generation circuit 20 also generates an update signal Supdate, for example, at an H level, at a predetermined second period T2 and outputs it to the clock terminal of the delay flip-flop 26, thereby outputting the data stored in the delay flip-flop 26 to a DA converter 27. The DA converter 27 generates the input digital data as an analog maximum operating voltage setting value Vmps based on the reference voltage Vref.

[0024] The first period T1 is the period for reading the sensor values ​​from the illuminance sensor 12 and the temperature sensor 13, and the second period T2 is the period for updating the maximum operating voltage setting value Vmps. In FIG. 3, the first period T1 and the second period T2 are the same, but the present invention is not limited to this and may be set differently as described below. These periods T1 and T2 can be set as "timing setting data" from an external controller depending on the operating environment. By being able to change the periods T1 and T2, power consumption during operation can be reduced. For example, if the default values ​​of the periods T1 and T2 are set to once per minute, power consumption can be reduced by setting them to once per 10 minutes when used in an environment with stable illuminance and temperature, such as when constantly in the shade.

[0025] Fig. 4 is a circuit diagram showing an example of the configuration of a preparation circuit 200 that generates mapping data to be written to the memory 25 of Fig. 2. Also, Fig. 5 is a table showing an example of mapping data stored in the memory 25 of Fig. 2. A method for obtaining mapping data will be described below with reference to Figs. 4 and 5.

[0026] The preparation circuit 200 in Fig. 4 is configured with a control circuit 30, a voltage detector 31, a current detector 32, and an electronic variable load 33. As shown in Fig. 4, the output terminal of the solar cell 1 is connected to both terminals of the voltage detector 31. In addition, an environment setting device 300 (e.g., consisting of an artificial solar lamp, a thermostatic bath, etc.) that can freely change the illuminance and temperature of the solar cell 1 is installed near the solar cell 1. The control circuit 30 gradually reduces the output current of the solar cell 1 by increasing the resistance value of the electronic variable load 33, measures the voltage and current at that time using the voltage detector 31 and the current detector 32, respectively, calculates the power from the product of these values, and calculates the voltage at the maximum power as the maximum operating voltage and writes it to memory 25.

[0027] Here, the temperature is represented by, for example, 3 bits (8 levels), and the illuminance is represented by 5 bits (32 levels). The temperature is changed from -5°C to 65°C in 10°C increments, and the illuminance is changed logarithmically from 100lx to 100,000lx (100, 200, ... 1,000, 2,000, ... 90,000, 100,000lx). The above data is acquired for each type of solar cell 1 used.

[0028] Figure 5 shows an example of the acquired mapping data, which is mapped into a 28 (illuminance) x 8 (temperature) space. As is clear from Figure 5, when the illuminance is 1,000 [lx] and the temperature is 35 [°C], the address is 0b01010100 (0x54), and a value indicating 4.5 [V] is written to memory 25. In addition, for example, when the illuminance is less than 100 [lx] or exceeds 100,000 [lx], and is outside the operating range, the value is rounded to, for example, 100 [lx] or 100,000 [lx].

[0029] FIG. 6 is a time series graph of the input voltage Vin, the output voltage Vfb, the comparison result signals V16 and V17 of the comparators 16 and 17, and the gate control voltage Vg of the voltage control circuit 10, illustrating an example of the operation of MPPC (maximum power point control) executed by the DC / DC converter 100 of FIG.

[0030] In FIG. 6, the DC / DC converter 100 outputs power at the maximum operating voltage Vmp, which is the voltage at which the solar cell 1 generates the maximum power. Upon receiving power from the solar cell 1, the DC / DC converter 100's input voltage Vin rises. When it reaches the maximum operating voltage Vmp, the MOS transistor Q1 starts switching, transmitting power to the load 3. Here, the input voltage Vin decreases when the MOS transistor Q1 is turned on, and increases when it is turned off (601). If the MOS transistor Q1 is left off, the input voltage Vin is fixed near the open-circuit voltage of the solar cell 1, as shown in FIG. 6. That is, when the amount of power transfer exceeds the power supplied from the solar cell 1, the MOS transistor Q1 switches on, reducing the input voltage Vin. At a predetermined voltage Vml, the MOS transistor Q1 stops switching, and the converter switches to charging mode. Then, when the input voltage Vin reaches the maximum operating voltage Vmp again, power is transmitted to the load 3. By repeating this operation, power can be transmitted to the load 3 while maintaining the operating point at which the solar cell 1 generates the maximum power. When sufficient power can be supplied to the load 3 such as a secondary battery, the output voltage Vfb reaches the output voltage set value Vfbset and the switching operation stops, and when the output voltage Vfb falls below a predetermined voltage Vfbsta (602), the switching operation starts.

[0031] As shown in FIG. 6, the comparison circuits 16 and 17 and the voltage control circuit 10 of FIG. 1 operate as follows. When the input voltage Vin rises and exceeds the maximum operating voltage Vmp, the comparison circuit 16 outputs a high-level comparison result signal V16. When the input voltage Vin falls and becomes equal to or lower than Vml, the comparison circuit 16 outputs a low-level comparison result signal V16. When the output voltage Vfb rises and exceeds Vfbset, the comparison circuit 16 outputs a low-level comparison result signal V17. When the output voltage Vfb falls and becomes equal to or lower than Vfbsta, the comparison circuit 16 outputs a high-level comparison result signal V17. The voltage control circuit 10 generates a gate control voltage Vg for the MOS transistor Q1 based on the comparison result signals V16 and V17.

[0032] The detailed operation of the DC / DC converter 100 configured as shown in FIGS. 1 and 2 will be described below.

[0033] First, timing generation circuit 20 in Fig. 2 changes read signal Sread from L level to H level at a predetermined sensor read timing (for example, once an hour, or once every few minutes). This timing is stored in a memory within timing generation circuit 20 or another memory. Next, when read signal Sread changes to H level, detection power supply voltage Vsens is supplied to illuminance sensor 12 and temperature sensor 13, and detection voltages Vl and Vt according to illuminance and temperature are input from illuminance sensor 12 and temperature sensor 13 to voltage conversion and amplification circuits 21 and 22, respectively, of maximum operating voltage tracking circuit 14 in Fig. 2. AD converter 23 is configured to output a value proportional to the logarithm of the illuminance, for example, and AD converter 24 is configured to output a digital value (maximum operating voltage) proportional to the temperature, such as a digital value stored at 3-bit address 0b001 when the temperature is 5°C, and a digital value stored at address 0b111 when the temperature is 65°C.AD converters 23 and 24 generate a total of 8 bits of address data which are input to the address bus of memory 25.

[0034] Because an H-level read signal Sread is input to the OE terminal of memory 25, when address data is input, the maximum operating voltage value (8 bits) corresponding to the address mapped in FIG. 5 is output from memory 25 to delay flip-flop 26. At a timing assumed after the output data from memory 25 is finalized (a fixed delay after read signal Sread changes from L level to H level), one pulse of update signal Supdate (clock) is output to the clock input terminal of delay flip-flop 26. At this time, at the rising edge of update signal Supdate (clock), delay flip-flop 26 outputs the stored data as the maximum operating voltage setting value Vmps via DA converter 27. Here, DA converter 27 converts the 8-bit data into an analog maximum operating voltage setting value Vmps and outputs it to comparison circuit 16 in FIG. 1. Voltage control circuit 10 of DC / DC converter 100 controls the current from solar cell 1 to obtain the changed maximum operating voltage, thereby drawing in power. Furthermore, when the update signal Supdate (clock) falls, the read signal Sread also falls, and the data update ends. [Example]

[0035] The method of improving MPPC according to this embodiment will be described below with examples showing specific advantages over the MPPC method.

[0036] Fig. 7 is a graph showing voltage-power characteristics in Case 1 of an embodiment of DC / DC converter 100 in Fig. 1. Fig. 8 is a graph showing voltage-power characteristics in Case 2 of an embodiment of DC / DC converter 100 in Fig. 1.

[0037] (Case 1) When the target value for the MPPC is set to the maximum operating voltage Vmp (4.1 V) at 800 lx and 55°C, and the same method is used to draw power in an environment of 100,000 lx and 5°C, the estimated power draw is 88 mW, which is about 24% less efficient than the estimated power draw of this embodiment, 116 mW. In other words, this embodiment can draw maximum power (see FIG. 7).

[0038] (Case 2) When the target value for the MPPC is set to the maximum operating voltage Vmp (6.4 V) at 100,000 lx and 5°C, and power is taken in using the same method in an environment of 800 lx and 55°C, the open-circuit voltage (5.1 V) is lower than the maximum operating voltage Vmp, and power cannot be taken in. In other words, in this embodiment, maximum power can be taken in (see FIG. 8).

[0039] (Supplementary information on the effects of the embodiment) As explained above, the MPPT method monitors and calculates the output voltage and output current from a solar panel, and then changes and tracks these voltages and currents to maintain the maximum power point of the solar panel. This requires microcomputer control. Furthermore, high-speed monitoring and calculations in this circuit result in a heavy load on the microcomputer, resulting in increased energy consumption. Low-speed calculations require a long time to find the maximum power point, resulting in reduced power generation efficiency. Therefore, unless a certain level of solar cell system (medium-sized or larger) is used, the overall power generation efficiency does not improve, leading to high costs. Furthermore, increasing the speed of this method requires more complex circuits, calculation algorithms, and correction programs, which also contributes to high costs. In other words, this method is unsuitable for DC-DC converters for solar panels in low-cost IoT edge devices.

[0040] In addition, the maximum operating voltage of an MPPC varies depending on the code, but for a single code, the maximum operating voltage is fixed, so it cannot be dynamically changed based on the illuminance. This has the following disadvantages: (1) If a DC-DC converter with a high maximum operating voltage is operated in a low-light environment, it will not be able to take in power. (2) When a DC-DC converter with a low maximum operating voltage is operated in a high-illumination environment, it can take in power but the loss is large.

[0041] As described above, this embodiment provides a DC / DC converter 100 including a voltage control circuit 10 that controls the input voltage from solar cell 1 to a predetermined output voltage using a maximum power control method that maintains the operating point of the maximum operating voltage at which the power generation amount of solar cell 1 is maximized. The DC / DC converter 100 further includes a memory 25 that pre-measures and stores the maximum operating voltage corresponding to the illuminance on solar cell 1 and the temperature near solar cell 1, an illuminance sensor 12 that detects the illuminance on solar cell 1, and a temperature sensor 13 that detects the temperature near solar cell 1. Based on the detected illuminance and temperature, the voltage control circuit 10 searches for the maximum operating voltage stored in memory 25, sets the searched maximum operating voltage, and controls the input voltage from solar cell 1 using the maximum power control method. This method can therefore be implemented with a smaller circuit scale and lower cost than MPPT, and can constantly draw maximum power from the solar panel. [Industrial Applicability]

[0042] The power conversion device according to the present invention provides a DC-DC converter that converts power extracted from a solar cell panel into a secondary battery, for example, in an IoT edge device that operates by storing power obtained from a solar cell in a secondary battery. In particular, the present invention can provide a power conversion device for small outdoor equipment that has a smaller circuit scale and can be implemented at low cost than an MPPT and can always draw maximum power from a solar cell panel. [Explanation of symbols]

[0043] 1. Solar cells 2 inductors 3. Load 10 Voltage control circuit 11 Reference voltage generation circuit 12 Illuminance sensor 13 Temperature Sensor 14 Maximum operating voltage tracking circuit 15 Output voltage setting circuit 16,17 Comparison circuit 20 Timing generation circuit 20m memory 21, 22 Voltage conversion and amplification circuit 23,24 AD converter 25 memory 26 Delay Flip-Flop 27 DA converter 28 Interface 30 Control circuit 31 Voltage detector 32 Current detector 33 Electronic variable load 100 DC / DC Converter 200 Preparation circuit 300 Environment setting device Cin, Cout capacitor D1 Diode Q1~Q2 MOS transistor

Claims

1. A power conversion device including a control circuit that controls an input voltage from a solar cell to a predetermined output voltage using a maximum power control method that maintains an operating point of a maximum operating voltage at which the amount of power generated by the solar cell is maximized, a first storage unit that pre-measures and stores a maximum operating voltage for an illuminance on the solar cell and a temperature in the vicinity of the solar cell; an illuminance sensor that detects illuminance on the solar cell; a temperature sensor for detecting a temperature in the vicinity of the solar cell; the control circuit searches for a maximum operating voltage stored in the first storage unit based on the detected illuminance and the detected temperature, sets the searched maximum operating voltage, and controls the input voltage from the solar cell using the maximum power control method. Power conversion device.

2. the first storage unit stores, as storage data, data including the detected illuminance and the detected temperature as an address, and a maximum operating voltage corresponding to the illuminance and the temperature; The power conversion device according to claim 1 .

3. The power conversion device is further comprising a second storage unit connected to a subsequent stage of the first storage unit; the control circuit reads out, at a first timing, a maximum operating voltage stored at an address indicating the detected illuminance and the detected temperature from the first storage unit and stores the maximum operating voltage in the second storage unit; The power conversion device according to claim 2 .

4. the control circuit reads the read maximum operating voltage from the second storage unit at a second timing, updates the read maximum operating voltage, and sets the updated maximum operating voltage. The power conversion device according to claim 3 .

5. The power conversion device is a third storage unit that stores the first and second timings; The first and second timings are configured to be writable from an external control circuit. The power conversion device according to claim 4.

6. The period of the first timing is configured to be the same as or different from the period of the second timing. The power conversion device according to claim 5 .

7. The power conversion device is a DC / DC converter. The power conversion device according to any one of claims 1 to 6.

8. A control method for a power conversion device including a control circuit that controls an input voltage from a solar cell to a predetermined output voltage using a maximum power control method that maintains an operating point of a maximum operating voltage at which the amount of power generated by the solar cell is maximized, comprising: The power conversion device is a first storage unit that pre-measures and stores a maximum operating voltage for an illuminance on the solar cell and a temperature in the vicinity of the solar cell; an illuminance sensor that detects illuminance on the solar cell; a temperature sensor for detecting a temperature in the vicinity of the solar cell; The control method for the power conversion device includes: the control circuit searches for a maximum operating voltage stored in the first storage unit based on the detected illuminance and the detected temperature, sets the searched maximum operating voltage, and controls the input voltage from the solar cell using the maximum power control method. A method for controlling a power conversion device.

9. the first storage unit stores, as storage data, data including the detected illuminance and the detected temperature as an address, and a maximum operating voltage corresponding to the illuminance and the temperature; The method for controlling a power conversion device according to claim 8.

10. The power conversion device is further comprising a second storage unit connected to a subsequent stage of the first storage unit; The control method includes: the control circuit further includes a step of reading, at a first timing, from the first storage unit, a maximum operating voltage stored at an address indicating the detected illuminance and the detected temperature, and storing the maximum operating voltage in the second storage unit. The method for controlling a power conversion device according to claim 9.

11. The control method includes: the control circuit, at a second timing, reads out the read maximum operating voltage from the second storage unit, updates the read maximum operating voltage, and sets an updated maximum operating voltage. The method for controlling a power conversion device according to claim 10.

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