KR20230100975A - apparatus and method for Maximum power point tracking in photovoltaic system having flyback convertor - Google Patents

Abstract

Various embodiments of this document relate to a method and apparatus for tracking a maximum power point of a photovoltaic system including a flyback converter. A method for tracking the maximum power point in a photovoltaic power generation system including a flyback converter is based on the operation of measuring the input current of the primary side and the output voltage of the secondary side of the flyback converter, based on the measured input current and output voltage. Thus, an operation of calculating an effective duty ratio considering the leakage inductance of the flyback converter, an operation of calculating an input voltage of the primary side of the flyback inverter based on the effective duty ratio, and based on the calculated input voltage An operation of tracking the maximum power point may be included.

Description

Apparatus and method for maximum power point tracking in photovoltaic system having flyback convertor}

Various embodiments of this document relate to a method and apparatus for tracking a maximum power point of a photovoltaic system including a flyback converter.

Recently, as the power load used in a specific season and a specific time period rapidly increases according to a rapid increase in power demand, it causes a shortage of standby power at all times and causes accidents such as power outages. Accordingly, various methods for solving the power shortage problem are being researched and developed, and one of them is research on a solar power generation system.

The photovoltaic power generation system includes a power conversion device that generates a DC output signal by converting a high-level DC input signal output from a solar cell module. A maximum power point (MPP) of a solar cell module may change depending on an environment such as solar radiation or ambient temperature. Therefore, in a photovoltaic power generation system, a maximum power point tracking (MPPT) technique is used to increase energy efficiency.

Most of the maximum power point tracking techniques require the detection of information about the input voltage and input current of the flyback converter included in the photovoltaic system. Therefore, conventionally, a method of measuring the input voltage and input current is used by providing a sensor for measuring the input voltage and input current of the flyback converter. However, there is a disadvantage in that a lot of cost is invested in constructing a solar power generation system due to sensors for measuring input voltage and input current.

Therefore, various embodiments of the present document disclose a method and apparatus for tracking a maximum power point without a sensor for measuring an input voltage in a photovoltaic power generation system including a flyback converter in order to solve the above problem.

The technical problem to be achieved in this document is not limited to the technical problem mentioned above, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description below. There will be.

According to various embodiments, a method for tracking a maximum power point in a photovoltaic power generation system including a flyback converter includes an operation of measuring an input current of a primary side and an output voltage of a secondary side of a flyback converter, the measured An operation of calculating an effective duty ratio considering the leakage inductance of the flyback converter based on the input current and an output voltage, an operation of calculating an input voltage of the primary side of the flyback inverter based on the effective duty ratio, and the An operation of tracking a maximum power point based on the calculated input voltage may be included.

According to one embodiment, the effective duty ratio, the average input current of the flyback converter, the average output voltage of the flyback converter, the measured duty ratio, the magnetizing inductance of the flyback converter, the leakage inductance of the flyback converter can be calculated based on

According to one embodiment, the input voltage of the primary side of the flyback inverter, the effective duty ratio, the measured duty ratio, the average output voltage of the flyback converter, the average input current of the flyback converter and the flyback Based on the leakage inductance of the converter, it can be calculated.

According to an embodiment, when the photovoltaic power generation system has a differential power control structure, the method further includes updating the input current by subtracting a specified minimum current from the measured input current, the effective duty ratio and the input current. The updated input current may be used instead of the measured input current for voltage calculation.

According to various embodiments, a solar power generation system including a flyback converter includes a photovoltaic (PV) module that generates power through power generation using solar energy, and converts an output voltage of the PV module into a pulsed DC voltage. and an MPPT control unit for controlling maximum power point tracking based on an input current on a primary side and an output voltage on a secondary side of the flyback converter, wherein the MPPT control unit comprises: Measure the input current of the primary side and the output voltage of the secondary side of the converter, calculate an effective duty ratio considering the leakage inductance of the flyback converter based on the measured input current and output voltage, and calculate the effective duty ratio Based on this, the input voltage of the primary side of the flyback inverter may be calculated, and the maximum power point may be tracked based on the calculated input voltage.

According to one embodiment, the MPPT controller, the average input current of the flyback converter, the average output voltage of the flyback converter, the measured duty ratio, the magnetizing inductance of the flyback converter, the leakage inductance of the flyback converter Based on this, the effective duty ratio can be calculated.

According to one embodiment, the MPPT control unit, based on the effective duty ratio, the measured duty ratio, the average output voltage of the flyback converter, the average input current of the flyback converter, and the leakage inductance of the flyback converter , the input voltage of the primary side of the flyback inverter can be calculated.

According to an embodiment, when the photovoltaic system has a differential power control structure, the MPPT control unit updates the input current by subtracting a specified minimum current from the measured input current, and updates the effective duty ratio and the input current. The updated input current may be used instead of the measured input current for voltage calculation.

According to various embodiments of the present document, by tracking the maximum power point using a sensorless voltage calculation technique in a solar power generation system including a flyback converter, it is possible to obtain an effect of reducing system design cost. In addition, by calculating the effective duty ratio considering the leakage inductance in the photovoltaic power generation system including the flyback converter, it is possible to minimize the calculation error for the duty ratio.

1 is a block diagram of a photovoltaic system including a flyback converter according to various embodiments of the present disclosure.
2 is a circuit diagram of a flyback converter according to various embodiments of this document.
3 is a graph showing an effective duty ratio according to various embodiments of the present disclosure.
4 is a graph showing an input voltage calculated according to a sensorless voltage calculation technique according to various embodiments of the present disclosure.
5 is a detailed circuit diagram of a differential power conditioning system including a flyback converter according to various embodiments of the present disclosure.
6A is a graph showing MPPT results using voltage and current sensors according to the prior art.
6B is a graph showing MPPT results according to various embodiments of the present document.
7 is a flowchart for controlling maximum power point tracking in a photovoltaic power generation system including a flyback converter according to various embodiments of the present disclosure.

Hereinafter, various embodiments will be described in detail with reference to the accompanying drawings.

Regardless of the reference numerals, the same or similar components are given the same reference numerals, and overlapping descriptions thereof can be omitted.

The suffix 'module' or 'unit' for the components used in the following description is given or used interchangeably in consideration of ease of writing the specification, and does not itself have a meaning or role distinct from each other. In addition, 'module' or 'unit' means software or a hardware component such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC), but is not limited to software or hardware. A 'unit' or 'module' may be configured to reside in an addressable storage medium and may be configured to reproduce one or more processors. Thus, as an example, 'unit' or 'module' includes components such as software components, object-oriented software components, class components and task components, processes, functions, properties, may include procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Functions provided within one component, 'unit' or 'module' may be combined into a smaller number of components and 'units' or 'modules', or may be combined with additional components and 'units' or 'modules'. can be further separated by

Steps of a method or algorithm described in connection with some embodiments of the present invention may be directly embodied in hardware executed by a processor, a software module, or a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of recording medium known in the art. An exemplary recording medium is coupled to the processor, and the processor can read information from and write information to the storage medium. Alternatively, the recording medium may be integral with the processor. The processor and recording medium may reside within an application specific integrated circuit (ASIC). An ASIC may reside within a user terminal.

Terms including ordinal numbers, such as first and second, may be used to describe various components, but the components are not limited by the terms. These terms are only used for the purpose of distinguishing one component from another.

It is understood that when a component is referred to as being 'connected' or 'connected' to another component, it may be directly connected or connected to the other component, but other components may exist in the middle. It should be. On the other hand, when a component is referred to as being 'directly connected' or 'directly connected' to another component, it should be understood that no other component exists in the middle.

1 is a block diagram of a solar power system 100 including a flyback converter according to various embodiments of the present disclosure. The configuration of the solar power generation system 100 shown in FIG. 1 is an embodiment, and other components not shown in FIG. 1 may be further included. In addition, at least one of the components shown in FIG. 1 may be omitted. Some of the components shown in FIG. 1 may be separated into a plurality of components and configured as different chips, different parts, or different electronic circuits, and some components may be combined to form one chip. , may be composed of one component or one electronic circuit.

In the following description, operations of some components of FIG. 1 will be described with reference to FIGS. 2 to 5 . 2 is a circuit diagram of a flyback converter according to various embodiments of the present document, and FIG. 3 is a graph showing an effective duty ratio according to various embodiments of the present document. 4 is a graph showing an input voltage calculated according to a sensorless voltage calculation technique according to various embodiments of the present document, and FIG. 5 is a differential power control system including a flyback converter according to various embodiments of the present document. is a detailed circuit diagram of

Referring to FIG. 1 , a photovoltaic system 100 may include a photovoltaic module 110 , a flyback converter 120 , and an MPPT controller 130 .

The photovoltaic module 110 may include at least one solar cell that generates power through power generation using solar energy. The flyback converter 120 may be a power conversion device that converts the output voltage of the PV module 100 into a DC voltage in the form of a pulse and outputs it.

According to various embodiments, the MPPT controller 130 determines the maximum power point for the PV module 110 based on the input voltage (V _in ) and the input current (I _in ) of the primary side of the flyback converter. point, MPP) can be tracked to control the flyback converter 120 to operate at the maximum power point. According to an embodiment, the MPPT controller 130 calculates an effective duty ratio to calculate the input voltage (V _in ) used for maximum power point tracking (MPPT) without a sensor measuring the input voltage. It may include a unit 132, a sensorless voltage calculator 134, and a sensorless MPPT controller 136.

According to an embodiment, the effective duty ratio calculator 130 may calculate an effective duty ratio used for MPPT in the normal state of the flyback converter 120 . The effective duty ratio may mean a duty ratio in which a loss factor of the flyback converter 120 is reflected, rather than a duty ratio under ideal conditions.

In general, the relationship between the input voltage and the output voltage of the flyback converter 120 in which feedback control is performed may be expressed as in Equation 1 below.

Here, Vin may mean an input voltage of the flyback converter 120, and Vout may mean an output voltage of the flyback converter 120. D may mean a duty ratio for an input voltage and an output voltage.

Equation 1 shows the relationship between the input voltage and the output voltage under ideal conditions in which no loss occurs in the flyback converter 120. Therefore, when a loss actually occurs in the flyback converter 120 and the duty ratio is calculated using Equation 1, an error may occur in MPPT control.

Therefore, the effective duty ratio calculator 130 according to various embodiments of the present document may calculate an effective duty ratio in which the loss element is reflected by considering the leakage inductance, which is one of the loss elements of the flyback converter 130 . That is, in various embodiments of the present document, by calculating the effective duty ratio in consideration of the amount of power loss generated in the leakage inductance, it is possible to minimize an error caused by the duty ratio during the MPPT control operation.

According to an embodiment, the effective duty ratio calculator 130 may calculate the effective duty ratio as shown in Equation 2 below in consideration of the leakage inductance of the flyback converter 120 configured as shown in FIG. 2 .

Here, I _in may mean an average input current of the flyback converter per cycle, and V _out may mean an average output voltage of the flyback converter per cycle. Also, D may mean the measured duty ratio. For example, D may be a duty ratio obtained by measuring the output of the PI controller. D _eff denotes an effective duty ratio in which a loss factor is reflected, L _m denotes a magnetizing inductance of the flyback converter, and L _lk denotes a leakage inductance of the flyback converter. T may mean an interval of one period.

As shown in Equation 2, the effective duty ratio calculator 130 may calculate an effective duty ratio into which leakage inductance is reflected, based on measurable data and device values. Here, the measurable data may mean an input current (I _in ) measurable using a current sensor on the primary side of the flyback converter, and an output voltage (V _out ) measurable using a voltage sensor on the secondary side of the flyback converter. Except for this, the other parameters are values determined during the design of the flyback converter 120.

The results of the simulation for the technique of calculating the effective duty ratio based on Equation 2 above are shown in FIG. 3 . 3 shows waveforms of a general duty ratio (D, 301) calculated based on Equation 1 and waveforms of an effective duty ratio (D _eff , 303) calculated based on Equation 2. (a) of FIG. 3 shows the waveforms of a typical duty ratio (D, 301) and an effective duty ratio (D _eff , 303) for about 0.2 seconds from the time the flyback converter is turned on, and (b) of FIG. A part of section 311 of a) is enlarged. (b) of FIG. 3 shows a typical duty ratio (D, 301) and an effective duty ratio (D _eff , 303) while the flyback converter is in a steady state. Looking at (b) of FIG. 3, it can be seen that the general duty ratio (D, 301) and the effective duty ratio (D _eff , 303) are not the same, which means that the effective duty ratio (D _eff , 303) has a leakage inductance It can mean that has been reflected.

According to an embodiment, the sensorless voltage calculator 134 may calculate the input voltage of the primary side of the flyback converter 120 based on the effective duty ratio. That is, the sensorless voltage calculator 134 may calculate the input voltage of the primary side of the flyback converter 120 as shown in Equation 3 below without having a sensor for measuring the input voltage.

Here, V _in means the input voltage of the primary side of the flyback converter 120, D _eff means the effective duty ratio calculated by Equation 2, D is the duty obtained by measuring the output of the PI controller means rain. V _out may mean the average output voltage of the flyback converter per cycle, and I _in may mean the average input current of the flyback converter per cycle. L _lk means the leakage inductance of the flyback converter, and T can mean the interval of one cycle.

According to various embodiments of the present document, the primary-side input voltage of the flyback converter 120 may be calculated using the effective duty ratio as shown in Equation 3 above.

The result of the simulation to verify the error for the input voltage calculated based on Equation 3 is shown in FIG. 4 . 4 shows a first input voltage (M_V _in 401) measured using a voltage sensor according to the prior art, a second input voltage (D_V _in 403) calculated using a general duty ratio, and the A waveform of the third input voltage (D _eff , 405) calculated using the effective duty ratio is shown.

(a) of FIG. 4 shows the first input voltage (M_V _in , 401 ), the second input voltage (D_V _in , 403 ), and the third input voltage (D _eff , for about 0.2 seconds from when the flyback converter is turned on). 405), and (b) of FIG. 4 is an enlarged portion of a section 411 of (a). That is, (b) of FIG. 4 shows the first input voltage (M_V _in , 401 ), the second input voltage (D_V _in , 403 ), and the third input voltage (D _eff ) while the flyback converter is in a normal operating state. , 405). The simulation is for the situation where the primary input voltage of the flyback converter is controlled to be about 17.02 [V].

Looking at (b) of FIG. 4 , it can be seen that the average of the first input voltages M_V _in 401 measured using the voltage sensor is about 17.023 [V]. On the other hand, it can be seen that the second input voltage D_V _in 403 calculated using a general duty ratio is about 16.254 [V], and there is an error with the first input voltage M_V _in 401 . However, it can be seen that the third input voltage (D _eff , 405) calculated using the effective duty ratio proposed in this document is about 17.027 [V], which is very similar to the first input voltage (M_V _in , 401). there is. That is, a technique of calculating an input voltage based on an effective duty ratio in which power loss for leakage inductance is considered without a sensor measuring the input voltage may have the same performance as a technique of measuring the input voltage using a sensor. .

According to one embodiment, the sensorless MPPT control unit 136 is provided when the photovoltaic system 100 has a differential power processing (DPP) structure, and the input current (I _in ) measured through the sensor Based on , the input current (I′ _in ) required for calculating the effective duty ratio can be calculated. For example, when the solar power generation system 100 has a simple DPP structure having two solar panels as shown in FIG. 5 , the current sensor is located at an output end of the solar panel. Accordingly, the current measured through the current sensor is I _PVn , but in practice, the input current required for calculating the effective duty ratio and/or the input voltage is I _{in_n} . That is, in the DPP structure, the input current (I _in ) measured through the current sensor is I _PVn , not I _{in_n} . Accordingly, the sensorless MPPT controller 136 may convert the input current (I _PVn ) measured through the current sensor in the DPP structure in the same manner as in Equation 4 to obtain the required input current (I _{in_n} ).

Here, I _{in_n} may mean an input current required to calculate an effective duty ratio and/or an input voltage, and I _PVn may mean a current measured through a sensor disposed at an output terminal of the solar panel. I _{in_min} is the current flowing to the boost converter in the DPP structure, and may have the size of the minimum current available in the solar panel.

According to an embodiment, when the photovoltaic system 100 has a DPP structure, the sensorless MPPT controller 136 converts the required input current I _{in_n} calculated as in Equation 4 to the effective duty ratio calculator 132 ), and/or may be provided to the sensorless voltage calculator 134. In this case, the effective duty ratio calculator 132 and/or the sensorless voltage calculator 134 use the required input current (I _{in_n} ) provided from the sensorless MPPT controller 136 instead of the input current measured through the current sensor. ) can be set as the input current (I _in ) of the flyback converter and used for calculating the effective duty ratio and/or input voltage. Therefore, even when the photovoltaic power generation system 100 has a DPP structure, the output voltage of the solar panel, that is, the input voltage of the flyback converter, can be accurately calculated without additional devices or circuits.

According to one embodiment, the MPPT control unit 130 tracks the maximum power point based on the input voltage (V _in ) and the input current (I _in ) calculated as described above, and the flyback converter 120 determines the maximum power PI control can be performed to operate at a point.

6A is a graph showing MPPT results using voltage and current sensors according to the prior art, and FIG. 6B is a graph showing MPPT results according to various embodiments of the present document.

Referring to FIGS. 6A and 6B , the result of performing MPPT using a voltage sensor and a current sensor and the result of performing MPPT by calculating an input voltage based on an effective duty ratio, as proposed in this document, are almost the same can know That is, it can be seen that even when MPPT is performed based on the input voltage calculated based on the effective duty ratio without a voltage sensor as proposed in this document, the same performance as the conventional general MPPT technique can be obtained.

7 is a flowchart for controlling maximum power point tracking in a photovoltaic power generation system including a flyback converter according to various embodiments of the present disclosure. In the following embodiments, each operation may be performed sequentially, but not necessarily sequentially. For example, the order of each operation may be changed, or at least two operations may be performed in parallel.

Referring to FIG. 7 , the photovoltaic system 100 may measure the input current (I _in ) and the output voltage (V _out ) of the flyback converter in operation 701 . For example, the photovoltaic power generation system 100 uses a current sensor on the primary side of the flyback converter 110 and a voltage sensor on the secondary side of the flyback converter 110 to obtain input current (I _in ) and output voltage. (V _out ) can be measured. The input current (I _in ) and the output voltage (V _out ) may mean an average input current and an average output voltage for a specified time period.

In operation 703, the photovoltaic power generation system 100 may measure a duty ratio. The duty ratio may be measured through the output of a PI controller (not shown).

In operation 705, the photovoltaic system 100 may update the input current to be used for calculation in consideration of the DPP structure. For example, when the photovoltaic system 100 has a DPP structure, due to the current flowing to the boost converter, the input current required for calculating the actual effective duty ratio and/or the input voltage and the input measured by the current sensor in operation 701 Currents can be different. Therefore, when the photovoltaic system 100 has a DPP structure, as shown in Equation 4, by subtracting the minimum current (I _{in_min} ) provided to the boost converter from the current (I _PVn ) measured by the current sensor, the actual effective Calculate the input current (I _{in_n} ) required for calculating the duty ratio and/or input voltage, and set the calculated required input current (I _{in_n} ) as the input current (I _in ) to be used for calculating the effective duty ratio and/or input voltage. can According to one embodiment, operation 705 may be performed when the photovoltaic system 100 has a DPP structure. That is, when the photovoltaic system 100 does not have a DPP structure, operation 705 may be omitted. If operation 705 is omitted, the input current (I _in ) measured using the current sensor in operation 701 may be an input current required for calculating an actual effective duty ratio and/or input voltage.

In operation 707, the photovoltaic power generation system 100 may calculate an effective duty ratio D _eff considering power loss due to leakage inductance. The effective duty ratio D _eff can be calculated as shown in Equation 2.

At operation 709, the photovoltaic system 100 may calculate an input voltage (V _in ). The photovoltaic power generation system 100 may calculate the input voltage of the primary side of the flyback converter 120 based on the calculated effective duty ratio. For example, the photovoltaic power generation system 100 may calculate the input voltage based on the effective duty ratio, as shown in Equation 3, without having a sensor for measuring the input voltage.

At operation 711, the photovoltaic system 100 performs maximum power point tracking (MPPT) based on the calculated input voltage (V _in ) and input current (I _in ), and the flyback converter 120 determines the maximum power PI control operation can be performed to operate at a point.

100: solar power system 110: PV module
120: flyback converter 130: MPPT control unit
132: effective duty ratio calculator 134: sensorless voltage calculator
136: sensorless MPPT controller

Claims (13)

A method for tracking a maximum power point in a solar power generation system including a flyback converter,
measuring the input current of the primary side and the output voltage of the secondary side of the flyback converter;
calculating an effective duty ratio considering leakage inductance of the flyback converter based on the measured input current and output voltage;
calculating an input voltage of a primary side of the flyback inverter based on the effective duty ratio; and
and tracking a maximum power point based on the calculated input voltage.
According to claim 1,
The effective duty ratio is calculated based on the average input current of the flyback converter, the average output voltage of the flyback converter, the measured duty ratio, the magnetizing inductance of the flyback converter, and the leakage inductance of the flyback converter. .
According to claim 2,
The effective duty ratio is calculated based on the following equation,

Here, I _in means the average input current of the flyback converter per cycle, V _out means the average output voltage of the flyback converter per cycle, D means the measured duty ratio, D _eff means the effective duty ratio, L _m means the magnetizing inductance of the flyback converter, L _lk means the leakage inductance of the flyback converter, and T means the interval of the one cycle, method.
According to claim 2,
The input voltage on the primary side of the flyback inverter is
Method calculated based on the effective duty ratio, the measured duty ratio, the average output voltage of the flyback converter, the average input current of the flyback converter, and the leakage inductance of the flyback converter.
According to claim 4,
The input voltage of the primary side of the flyback inverter is calculated based on the following equation,

Here, V _in means the input voltage of the primary side of the flyback converter, D _eff means the effective duty ratio, D means the measured duty ratio, and V _out means the flyback per cycle. Means the average output voltage of the back converter, I _in is the average input current of the flyback converter per cycle, L _lk means the leakage inductance of the flyback converter, T means the interval of the one cycle How to.
According to claim 1,
When the photovoltaic power generation system has a differential power control structure, further comprising updating the input current by subtracting a specified minimum current from the measured input current,
and using the updated input current instead of the measured input current in calculating the effective duty ratio and the input voltage.
In a solar power generation system including a flyback converter,
Photovoltaic (PV) modules that generate electricity through solar energy generation;
a flyback converter that converts the output voltage of the PV module into a DC voltage in a pulse form and outputs it; and
An MPPT control unit for controlling maximum power point tracking based on the input current of the primary side and the output voltage of the secondary side of the flyback converter,
The MPPT control unit,
Measure the input current of the primary side and the output voltage of the secondary side of the flyback converter,
Calculate an effective duty ratio considering the leakage inductance of the flyback converter based on the measured input current and output voltage;
Calculate the input voltage of the primary side of the flyback inverter based on the effective duty ratio,
A solar power generation system that tracks a maximum power point based on the calculated input voltage.
According to claim 7,
The MPPT control unit,
Calculating the effective duty ratio based on the average input current of the flyback converter, the average output voltage of the flyback converter, the measured duty ratio, the magnetizing inductance of the flyback converter, and the leakage inductance of the flyback converter. photovoltaic system.
According to claim 8,
The MPPT control unit calculates the effective duty ratio based on the following equation,

Here, I _in means the average input current of the flyback converter per cycle, V _out means the average output voltage of the flyback converter per cycle, D means the measured duty ratio, D _eff means the effective duty ratio, L _m means the magnetizing inductance of the flyback converter, L _lk means the leakage inductance of the flyback converter, and T means the interval of the one cycle, solar power system.
According to claim 8,
The MPPT control unit,
The primary-side input voltage of the flyback inverter is based on the effective duty ratio, the measured duty ratio, the average output voltage of the flyback converter, the average input current of the flyback converter, and the leakage inductance of the flyback converter. Calculate the solar power system.
According to claim 10,
The MPPT control unit calculates the input voltage of the primary side of the flyback inverter based on the following equation,

Here, V _in means the input voltage of the primary side of the flyback converter, D _eff means the effective duty ratio, D means the measured duty ratio, and V _out means the flyback per cycle. Means the average output voltage of the back converter, I _in is the average input current of the flyback converter per cycle, L _lk means the leakage inductance of the flyback converter, T means the interval of the one cycle , solar power system.
According to claim 7,
The MPPT control unit,
When the photovoltaic system has a differential power control structure, updating the input current by subtracting a specified minimum current from the measured input current;
The solar power generation system using the updated input current instead of the measured input current in calculating the effective duty ratio and the input voltage.
In the computer readable storage medium,
A computer readable storage medium comprising a computer program which, when executed on a computer, performs a method according to any one of claims 1 to 6.

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