Power Control Device

Abstract

To enable a user to grasp whether or not a power conversion circuit is operated using a control system suitable for a power supply device being used.SOLUTION: A power conversion circuit 13 converts an input voltage into an output voltage. A voltage sensor 12 measures the input voltage. A control circuit 14 is capable of controlling the power conversion circuit 13 using any one of a plurality of control systems. Based on a specular change of the input voltage, the control circuit 14 selects a control system which operates the power conversion circuit 13 with highest efficiency in the plurality of control systems. An output device 15 outputs a first notification signal indicating the control system which operates the power conversion circuit 13 with the highest efficiency.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power control device. [Background technology]

[0002] Recently, with the growing interest in renewable energy, the use of solar cells, wind power generators, and the like has increased.

[0003] For example, Patent Document 1 discloses a combined power generation system in which a wind power generation system and a solar power generation system are connected in parallel. In this system, a DC / DC converter is connected in series to each of the wind power generation system and the solar power generation system, and the DC power of the wind power generation system and the solar power generation system is output in a time-division manner, thereby alternately selecting the DC output of the wind power generation system or the solar power generation system. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-145369 Summary of the Invention [Problem to be solved by the invention]

[0005] Various control schemes are known for operating power conversion circuits such as DC / DC converters. The power supply that is providing power to The most efficient control method is , electric The present inventors have found that when a power conversion circuit can receive power from any of a plurality of different power supply devices, the user cannot know whether the power conversion circuit is operating using a control method suitable for the power supply device in use, power supply However, we discovered a new issue: the inverter may operate at less than its maximum efficiency.

[0006] The present disclosure provides a power control device that includes a power conversion circuit, and that allows a user to determine whether the power conversion circuit is operating using a control method suitable for the power supply device in use. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, a power conversion circuit that converts an input voltage into an output voltage; a voltage sensor for measuring the input voltage; A control circuit capable of controlling the power conversion circuit using one of a plurality of control methods, the control circuit selecting one of the plurality of control methods based on a temporal change in the input voltage. power supply a control circuit for selecting a control method that operates the inverter with the highest efficiency; The aforementioned power supply and an output device that outputs a first notification signal indicating a control method that operates the inverter with the highest efficiency.

[0008] According to one aspect of the present disclosure, The control circuit controls the power conversion circuit using the selected control method.

[0009] the plurality of control methods include a first control method and a second control method; When the power conversion circuit is controlled by the first control method, the control circuit determines which of the first control method and the second control method is more efficient based on a temporal change in the input voltage; When it is determined that the second control method is more efficient than the first control method, the output device outputs a second notification signal indicating the second control method.

[0010] According to one aspect of the present disclosure, The control circuit controls the power conversion circuit by switching from the first control method to the second control method.

[0011] According to one aspect of the present disclosure, The control methods include constant voltage control and maximum power point tracking (MPPT) control.

[0012] According to one aspect of the present disclosure, When the input voltage is higher than a first threshold and the current time is nighttime, the control circuit power supply The constant voltage control is selected as the control method that allows the inverter to operate with the highest efficiency.

[0013] According to one aspect of the present disclosure, The control circuit If the number of fluctuations of the input voltage over a predetermined time period is less than a second threshold, power supply Selecting the MPPT control as the control method that operates the inverter with the highest efficiency, If the number of fluctuations is equal to or greater than the second threshold value, power supply The constant voltage control is selected as the control method that allows the inverter to operate with the highest efficiency.

[0014] According to one aspect of the present disclosure, The control circuit If a response time of the input voltage to the parameter of the power conversion circuit is shorter than a third threshold, power supply Selecting the MPPT control as the control method that operates the inverter with the highest efficiency, If the response time is equal to or greater than the third threshold, power supply The constant voltage control is selected as the control method that allows the inverter to operate with the highest efficiency. [Effects of the Invention]

[0015] According to one aspect of the present disclosure, a user can know whether or not the power conversion circuit is operating using a control method suitable for the power supply device in use. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a block diagram showing the configuration of a system including a power control device 1 according to an embodiment. [Figure 2]2 is a diagram showing the characteristics of the voltage and power generated by the solar cell 2 of FIG. 1. [Figure 3] 2 is a diagram schematically showing the characteristics of voltage and power generated by the wind power generator 3 of FIG. 1. FIG. [Figure 4] 2 is a flowchart showing a power control process executed by the control circuit 14 of FIG. [Figure 5] 5 is a flowchart showing a subroutine of step S3 (control method determination process) in FIG. [Figure 6] 6 is a flowchart showing a subroutine of step S11 (determination process based on the current time) in FIG. 5. [Figure 7] 6 is a flowchart showing a subroutine of step S12 (determination process based on voltage fluctuation) in FIG. 5. [Figure 8] 6 is a flowchart showing a subroutine of step S13 (determination process based on voltage response) in FIG. 5. [Figure 9] 9 is a diagram for explaining measurement of response time Tr in step S41 of FIG. 8. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, a system including a power control device according to an embodiment of the present invention will be described with reference to the drawings. The same reference numerals denote similar components throughout the drawings.

[0018] [Embodiment] [Configuration of the embodiment] FIG. 1 is a block diagram showing the configuration of a system including a power control device 1 according to an embodiment. The system of FIG. 1 includes the power control device 1, a solar cell 2, a wind power generator 3, and a load device 4. The power control device 1 receives an input voltage from the solar cell 2 or the wind power generator 3, converts the input voltage to a predetermined output voltage, and supplies it to the load device 4. The solar cell 2 and the wind power generator 3 are examples of power supply devices. The solar cell 2 and the wind power generator 3 output a DC voltage. The wind power generator 3 may include an AC motor and a rectifier circuit. The load device 4 operates on the DC voltage.

[0019] The power control device 1 includes a switch 11 , a voltage sensor 12 , a power conversion circuit 13 , a control circuit 14 , an output device 15 , and an input device 16 .

[0020] The switch 11 selectively connects one of the solar cell 2 and the wind power generator 3 to the power conversion circuit 13. As a result, the output voltage of the solar cell 2 or the wind power generator 3 is supplied as an input voltage to the power conversion circuit 13. The switch 11 may be switched manually by a user, or may be switched electronically in response to a control signal from an external device.

[0021] The voltage sensor 12 measures the input voltage of the power conversion circuit 13 .

[0022] The power conversion circuit 13 converts the input voltage supplied from the solar cell 2 or the wind power generator 3 into a desired output voltage and supplies it to the load device 4. The power conversion circuit 13 is a DC / DC converter including a primary side circuit 21, a transformer 22, and a secondary side circuit 23. The primary side circuit 21 includes one or more switching elements that operate under the control of the control circuit 14, and converts the DC input voltage into an AC voltage and applies it to the primary winding of the transformer 22. When an AC voltage is applied to the primary winding, the transformer 22 generates an AC voltage in the secondary winding. The secondary side circuit 23 includes a rectifier circuit and a smoothing circuit, and converts the AC voltage generated in the secondary winding of the transformer 22 into a DC output voltage.

[0023] The control circuit 14 controls the power conversion circuit 13 using one of a plurality of control methods. The plurality of control methods include, for example, constant voltage control and maximum power point tracking (MPPT) control. The control circuit 14 controls the power conversion circuit 13 to start or stop power supply to the load device 4 in response to a user input acquired via the input device 16. The control circuit 14 selects one of the plurality of control methods, i.e., Solar cell 2 or wind turbine 3The control circuit 14 also includes a clock 14a that supplies the current time, and a memory 14b that stores the history of the input voltage measured by the voltage sensor 12.

[0024] The output device 15 is selected by the control circuit 14. Solar cell 2 or wind turbine 3 The output device 15 outputs a notification signal indicating a control method for operating the device with the highest efficiency. The output device 15 may be a display that generates a visual notification signal, or a buzzer or speaker that generates an audible notification signal. The output device 15 may also be a communication interface connected to a remote device via a communication line. In this case, the remote device is equipped with a display, buzzer, speaker, etc.

[0025] The input device 16 acquires a user input instructing the start and stop of power supply to the load device 4 and sends it to the control circuit 14. The input device 16 also acquires a user input specifying one of a plurality of control methods and sends it to the control circuit 14. The input device 16 may include a keyboard and a pointing device, or may include a communication interface connected to a remote device via a communication line.

[0026] The user refers to the notification signal output from the output device 15 and uses the input device 16 to Solar cell 2 or wind turbine 3 In this case, the control circuit 14 controls the power conversion circuit 13 using the control method designated by the user input acquired via the input device 16. The control circuit 14 may also control the power conversion circuit 13 using the control method ( Solar cell 2 or wind turbine 3 The power conversion circuit 13 may be automatically controlled using a control method that operates the power conversion circuit 13 with the highest efficiency.

[0027] [Operation of the embodiment] First, referring to FIGS. 2 and 3, solar cell 2 or A control method for the power conversion circuit to operate the wind power generator 3 with high efficiency will be described.

[0028] FIG. 2 is a diagram schematically illustrating the characteristics of the voltage and power generated by the solar cell 2 of FIG. 1. Generally, the maximum power generated by a solar cell varies depending on the intensity of solar radiation. As shown by peaks P1 and P2, as the maximum power value changes, the voltage at which power is maximized also changes. The intensity of solar radiation varies depending on the weather, but the rate of change is relatively slow. Therefore, to maximize the power generation efficiency of the solar cell 2, the control circuit 14 preferably controls the power conversion circuit 13 using MPPT control, which searches for the maximum power point by varying the operating voltage. The control circuit 14 changes the operating voltage (input voltage) of the power conversion circuit 13 by changing the duty ratio of the primary side circuit 21. Decreasing the duty ratio increases the input voltage, and increasing the duty ratio decreases the input voltage.

[0029] FIG. 3 is a diagram illustrating the characteristics of the voltage and power generated by the wind power generator 3 of FIG. 1. Generally, in a wind power generator, the maximum power generated varies depending on the wind speed. As shown by peaks P11 and P12, even if the maximum power generated changes, the voltage at which power is maximized does not change. Because the power that can be generated by the wind power generator 3 varies significantly depending on the wind speed (the cube of the wind speed), MPPT control cannot effectively utilize the generated power. If the power converted by the power conversion circuit 13 is too small compared to the power generated by the wind power generator 3, the rotation speed of the wind turbine will become too high, potentially damaging the wind power generator 3. Conversely, if the power converted by the power conversion circuit 13 is too large compared to the power generated by the wind power generator 3, the rotation of the wind turbine will be suppressed, reducing power generation efficiency. Therefore, to maximize the power generation efficiency of the wind power generator 3, the control circuit 14 preferably controls the power conversion circuit 13 using constant voltage control.

[0030] The voltage of the constant voltage operating point may be determined, for example, by intentionally varying the operating voltage of the power conversion circuit 13 and determining the voltage at which maximum power is reached. Alternatively, the voltage of the constant voltage operating point may be determined by performing such a determination process multiple times and determining the average or most frequent value of multiple determined voltages. The voltage of the constant voltage operating point may be determined in advance when the power control device 1 is designed or manufactured, or may be determined during a previous operation of the power control device 1. The voltage of the constant voltage operating point is stored in a non-volatile memory (not shown).

[0031] When using a single power conversion circuit 13 to convert both the power generated by the solar cell 2 and the power generated by the wind power generator 3, it is desirable to switch the control method of the power conversion circuit 13 due to the above-mentioned problems. That is, when converting the power generated by the solar cell 2, the power conversion circuit 13 is controlled using MPPT control, and when converting the power generated by the wind power generator 3, the power conversion circuit 13 is controlled using constant voltage control. This allows for maximum utilization of renewable energy. Therefore, it is conceivable to store the type of power supply device to be used in advance in a non-volatile memory or the like provided in the system before operation. However, if a setting error occurs due to human error by the system installer, the user may not recognize the setting error, and as a result, the power generation efficiency may continue to decrease for a long period of time. For example, when the power conversion circuit 13 is controlled using constant voltage control when converting the power generated by the solar cell 2, it may not necessarily operate at the maximum power point, as shown by point P3 in Figure 2. On the other hand, when controlling the power conversion circuit 13 using MPPT control when converting the power generated by the wind power generator 3, there is a risk of continuing a wasteful search to determine the maximum power point. While searching for the maximum power point in MPPT control, Solar cell 2 or wind turbine 3 does not operate at maximum efficiency. In addition, solar radiation generally changes slowly, and the control cycle of MPPT control is slow. If MPPT control is performed in an environment where the power curve changes frequently, such as wind turbine 3, the search for the maximum power point will not be completed and the system will operate in a constant state of searching, making it impossible to generate power efficiently.

[0032] Therefore, in order to switch the control method of the power conversion circuit 13, the user is required to know whether the power conversion circuit 13 is operating using a control method suitable for the power supply device in use. The operation of the power control device 1 according to the embodiment that solves this problem will be described below.

[0033] FIG. 4 is a flowchart showing the power control process executed by the control circuit 14 of FIG.

[0034] In step S1, the control circuit 14 determines whether or not a user input instructing the start of power supply to the load device 4 has been received from the input device 16; if YES, the control circuit 14 proceeds to step S2; if NO, the control circuit 14 repeats step S1.

[0035] In step S2, the control circuit 14 determines whether the current input voltage Vin measured by the voltage sensor 12 exceeds the threshold value Vth. If the result is YES, the control circuit 14 proceeds to step S3. If the result is NO, the control circuit 14 ends the process. The threshold value Vth may be set to 0 V or may be set near the minimum voltage at which the power conversion circuit 13 can operate.

[0036] In step S3, the control circuit 14 executes a control method determination process to determine a control method suitable for the power supply device in use, i.e., Solar cell 2 or wind turbine 3 Determine the control method that will operate the system with the highest efficiency.

[0037] In step S4, the control circuit 14 notifies the user by causing the output device 15 to output a notification signal indicating the control method suitable for the power supply device in use.

[0038] In step S5, the control circuit 14 controls the power conversion circuit 13 using a control method suitable for the power supply device in use, in response to a user input acquired via the input device 16. Alternatively, the control circuit 14 may automatically control the power conversion circuit 13 using a control method suitable for the power supply device in use.

[0039] In step S6, the control circuit 14 determines whether or not a user input instructing the stopping of power supply to the load device 4 has been received from the input device 16, and if YES, ends the processing, and if NO, returns to step S3.

[0040] When executing step S4 after starting the power conversion circuit 13, the control circuit 14 may cause the output device 15 to output a notification signal (or warning) only if the control method suitable for the power supply device in use is different from the control method in use.

[0041] Fig. 5 is a flowchart showing a subroutine of step S3 (control method determination process) in Fig. 4. The control circuit 14 executes steps S11 to S13 in parallel. In step S11, the control circuit 14 executes determination process based on the current time. In step S12, the control circuit 14 executes determination process based on the voltage history. In step S13, the control circuit 14 executes determination process based on the voltage response.

[0042] FIG. 6 is a flowchart showing a subroutine of step S11 (determination process based on the current time) in FIG.

[0043] In step S21, the control circuit 14 obtains the current time from the clock 14a.

[0044] In step S22, the control circuit 14 determines whether the current time is nighttime or not, and if YES, the process proceeds to step S23, and if NO, the process returns to the process of FIG.

[0045] In step S23, the control circuit 14 determines constant voltage control as the control method suitable for the power supply device in use. If an input voltage Vin exceeding the threshold Vth occurs at night, it is considered that the input voltage from the wind power generator 3, not the solar cell 2, is being applied to the power conversion circuit 13.

[0046] On the other hand, if the input voltage Vin does not exceed the threshold value Vth at night, it is not possible to determine whether the solar cell 2 is in use or whether the wind power generator 3 is in use and there is no wind. In this case, the control circuit 14 sets one of the predetermined control methods as the control method suitable for the power supply device in use, or sets the control method that was last used.

[0047] FIG. 7 is a flowchart showing a subroutine of step S12 (determination process based on voltage fluctuation) in FIG.

[0048] In step S31, the control circuit 14 reads the history of the input voltage Vin from the memory 14b.

[0049] In step S32, the control circuit 14 calculates the number of times Nv the input voltage Vin fluctuates over a predetermined time period. For example, the control circuit 14 may calculate the average value Vav of the input voltage Vin over a three-minute period, set thresholds V1=Vav×0.5 and V2=Vav×1.5, and calculate the number of times Nv the input voltage Vin crosses the threshold V1 or V2.

[0050] In step S33, the control circuit 14 determines whether the number of fluctuations Nv is less than a threshold value Nth (for example, Nth=10), and if YES, the process proceeds to step S34, and if NO, the process proceeds to step S35.

[0051] In step S34, the control circuit 14 determines MPPT control as the control method suitable for the power supply device in use. As described above, since solar radiation generally changes slowly, when the number of fluctuations Nv is equal to the threshold value Nth, it is considered that the input voltage from the solar cell 2 is being applied to the power conversion circuit 13.

[0052] In step S35, the control circuit 14 determines constant voltage control as the control method suitable for the power supply device in use. Since wind power changes more frequently than solar radiation changes, if the number of fluctuations Nv is equal to or greater than the threshold value Nth, it is considered that the input voltage from the wind power generator 3 is being applied to the power conversion circuit 13.

[0053] FIG. 8 is a flowchart showing a subroutine of step S13 (determination process based on voltage response) in FIG.

[0054] In step S41, the control circuit 14 changes the duty ratio D of the primary side circuit 21 from 100% to 0%, and measures the response time Tr of the input voltage Vin.

[0055] 9 is a diagram for explaining the measurement of response time Tr in step S41 of FIG. 8. When the load of the power supply device (i.e., the current flowing through the power conversion circuit 13) increases, the output voltage of the power supply device decreases. The solar cell 2 responds almost instantaneously to load fluctuations, but the wind power generator 3 has a longer response time to load fluctuations. Therefore, the control circuit 14 measures the response time Tr, for example, from when the duty ratio D of the primary side circuit 21 is changed from 100% to 0% until the input voltage Vin reaches a predetermined threshold value V0 (e.g., 90% of the rated voltage).

[0056] 8, the control circuit 14 determines whether the response time Tr is less than a threshold value Tth, and if YES, proceeds to step S43, and if NO, proceeds to step S44. The threshold value Tth is set to, for example, 100 milliseconds.

[0057] In step S43, the control circuit 14 determines MPPT control as the control method suitable for the power supply device in use.

[0058] In step S44, the control circuit 14 determines constant voltage control as the control method suitable for the power supply device in use.

[0059] [Effects of the embodiment] According to the power control device 1 according to the embodiment, Solar cell 2 or wind turbine 3 The control circuit 14 outputs a notification signal indicating the control method that will operate the power conversion circuit 13 with the highest efficiency, so that the user can determine the control method that is most suitable for the power supply device being used and control the power conversion circuit using this control method. Solar cell 2 or wind turbine 3 Alternatively, the power conversion circuit 13 may be automatically controlled using a control method that allows the power conversion circuit 13 to operate with the highest efficiency.

[0060] According to the power control device 1 of the embodiment, when the control circuit 14 controls the power conversion circuit 13 using a certain control method, the control circuit 14 performs the following operation based on the temporal change in the input voltage: Solar cell 2 or wind turbine 3 Other control schemes may be selected that operate more efficiently. Solar cell 2 or wind turbine 3 By outputting a notification signal indicating a control method that will operate the power conversion circuit with higher efficiency, the user can know whether the power conversion circuit is operating using a control method that is suitable for the power supply device being used. If the power conversion circuit is not operating using a control method that is suitable for the power supply device being used, the user can Solar cell 2 or wind turbine 3 The control circuit 14 can operate the power conversion circuit 13 using a control method that allows the power conversion circuit 13 to operate with higher efficiency. Solar cell 2 or wind turbine 3 Alternatively, the power conversion circuit 13 may be automatically controlled using a control method that allows the power conversion circuit 13 to operate more efficiently.

[0061] According to the power control device 1 of the embodiment, in a system in which multiple power supply devices are connected to one power conversion circuit 13, it is possible to determine whether a preset power supply device is actually connected and to issue a warning if the preset power supply device is incorrect. According to the power control device 1 of the embodiment, in such a system, it is not necessary to preset the power supply device to be connected.

[0062] [Other embodiments] The control circuit 14 may execute only one or two of steps S11 to S13 in FIG.

[0063] The power supply device is not limited to the wind power generator 3, but may include other generators including a motor, such as a hydraulic generator. The generator including a motor has the characteristics shown in FIG. 3, similar to the wind power generator 3, and is operated using constant voltage control. generator can be operated with high efficiency.

[0064] The power conversion circuit 13 may be connected to a single unknown power supply device without going through the switch 11, instead of being connected to a plurality of power supply devices via the switch 11 as shown in FIG.

[0065] The power conversion circuit 13 is not limited to an insulating converter including a transformer 22 as shown in FIG. 1, but may be a non-insulating converter that does not include a transformer.

[0066] When the load device 4 operates on an AC voltage, the power control device 1 may include a DC / AC inverter instead of the power conversion circuit 13 which is a DC / DC converter.

[0067] The threshold value Vth in step S2 of Fig. 4 may be set in advance or may be calculated based on the history of the input voltage Vin after installation of the power control device 1. Furthermore, the threshold value Nth in step S33 of Fig. 7 may be set in advance or may be calculated based on the history of the input voltage Vin and the history of the number of fluctuations Nv after installation of the power control device 1. Furthermore, the threshold value Tth in step S42 of Fig. 8 may be set in advance or may be calculated based on the actual response time Tr of the power supply device in use after installation of the power control device 1.

[0068] The control circuit 14, the output device 15, and the input device 16 are not limited to being integrated into the power control device 1, but may be provided remotely from the power conversion circuit 13 via a communication line.

[0069] [Summary of the embodiment] According to a first aspect of the present disclosure, a power conversion circuit that converts an input voltage into an output voltage; a voltage sensor for measuring the input voltage; A control circuit capable of controlling the power conversion circuit using one of a plurality of control methods, the control circuit selecting one of the plurality of control methods based on a temporal change in the input voltage. power supply a control circuit for selecting a control method that operates the inverter with the highest efficiency; The aforementioned power supply and an output device that outputs a first notification signal indicating a control method that operates the inverter with the highest efficiency.

[0070] According to a second aspect of the present disclosure, in the first aspect, The control circuit controls the power conversion circuit using the selected control method.

[0071] According to a third aspect of the present disclosure, in the first or second aspect, the plurality of control methods include a first control method and a second control method; When the power conversion circuit is controlled by the first control method, the control circuit determines which of the first control method and the second control method is more efficient based on a temporal change in the input voltage; When it is determined that the second control method is more efficient than the first control method, the output device outputs a second notification signal indicating the second control method.

[0072] According to a fourth aspect of the present disclosure, in the third aspect, The control circuit controls the power conversion circuit by switching from the first control method to the second control method.

[0073] According to a fifth aspect of the present disclosure, in one of the first to fourth aspects, The control methods include constant voltage control and maximum power point tracking (MPPT) control.

[0074] According to a sixth aspect of the present disclosure, in the fifth aspect, When the input voltage is higher than a first threshold and the current time is nighttime, the control circuit power supplyThe constant voltage control is selected as the control method that allows the inverter to operate with the highest efficiency.

[0075] According to a seventh aspect of the present disclosure, in the fifth aspect, The control circuit If the number of fluctuations of the input voltage over a predetermined time period is less than a second threshold, power supply Selecting the MPPT control as the control method that operates the inverter with the highest efficiency, If the number of fluctuations is equal to or greater than the second threshold value, power supply The constant voltage control is selected as the control method that allows the inverter to operate with the highest efficiency.

[0076] According to an eighth aspect of the present disclosure, in the fifth aspect, The control circuit If a response time of the input voltage to the parameter of the power conversion circuit is shorter than a third threshold, power supply Selecting the MPPT control as the control method that operates the inverter with the highest efficiency, If the response time is equal to or greater than the third threshold, power supply The constant voltage control is selected as the control method that allows the inverter to operate with the highest efficiency. [Industrial Applicability]

[0077] A power control device according to an embodiment of the present disclosure is applicable to a multi-source power conditioner that uses one power conversion circuit to convert both of the powers generated by multiple power supply devices. [Explanation of symbols]

[0078] 1 Power control device 2. Solar cells 3. Wind turbines 4 Load device 11 Switch 12 Voltage Sensor 13 Power Conversion Circuit 14 Control circuit 14a Clock 14b memory 15 Output Devices 16 Input Devices 21 Primary circuit 22 Transformer 23 Secondary circuit

Claims

1. A power conversion circuit that converts an input voltage supplied from a power supply device into an output voltage; a voltage sensor for measuring the input voltage; a control circuit capable of controlling the power conversion circuit using one of a plurality of control methods, the control circuit selecting, from the plurality of control methods, a control method that allows the power supply device to operate with the highest efficiency based on a change over time in the input voltage; an output device that outputs a first notification signal indicating a control method for operating the power supply device with the highest efficiency; Power control device.

2. the control circuit controls the power conversion circuit using the selected control method. The power control device according to claim 1 .

3. the plurality of control methods include a first control method and a second control method, When the power conversion circuit is controlled by the first control method, the control circuit determines which of the first control method and the second control method is more efficient based on a temporal change in the input voltage; When it is determined that the second control method is more efficient than the first control method, the output device outputs a second notification signal indicating the second control method. The power control device according to claim 1 .

4. the control circuit controls the power conversion circuit by switching from the first control method to the second control method. The power control device according to claim 3.

5. The plurality of control methods include constant voltage control and maximum power point tracking (MPPT) control. A power control device according to any one of claims 1 to 4.

6. the control circuit selects the constant voltage control as a control method for operating the power supply device with the highest efficiency when the input voltage is higher than a first threshold value and the current time is nighttime. The power control device according to claim 5.

7. The control circuit If the number of fluctuations of the input voltage over a predetermined time period is less than a second threshold, the MPPT control is selected as the control method for operating the power supply device with the highest efficiency; When the number of fluctuations is equal to or greater than the second threshold value, the constant voltage control is selected as the control method for operating the power supply device with the highest efficiency. The power control device according to claim 5.

8. The control circuit If a response time of the input voltage to the parameter of the power conversion circuit is shorter than a third threshold, the MPPT control is selected as a control method for operating the power supply device with the highest efficiency; If the response time is equal to or greater than the third threshold value, the constant voltage control is selected as the control method for operating the power supply device with the highest efficiency. The power control device according to claim 5.

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