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WO2023243770A1 - Algorithme de suivi de point de puissance maximale à boucles doubles séparées, et convertisseur cc-cc pour son exécution - Google Patents

Algorithme de suivi de point de puissance maximale à boucles doubles séparées, et convertisseur cc-cc pour son exécution Download PDF

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Publication number
WO2023243770A1
WO2023243770A1 PCT/KR2022/013883 KR2022013883W WO2023243770A1 WO 2023243770 A1 WO2023243770 A1 WO 2023243770A1 KR 2022013883 W KR2022013883 W KR 2022013883W WO 2023243770 A1 WO2023243770 A1 WO 2023243770A1
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WO
WIPO (PCT)
Prior art keywords
power
voltage
converter
reference voltage
output stage
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PCT/KR2022/013883
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English (en)
Korean (ko)
Inventor
김은서
Original Assignee
주식회사 커널로그
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Publication of WO2023243770A1 publication Critical patent/WO2023243770A1/fr

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
    • H02S40/30—Electrical components
    • H02S40/32—Electrical components comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules

Definitions

  • the present invention relates to a maximum power point tracking (MPPT) algorithm that operates in an isolated double loop, and discloses a DC-DC converter for an energy harvesting system that performs this.
  • MPPT maximum power point tracking
  • Energy harvesting is a technology that harvests natural energy generated around us and converts it into electrical energy.
  • a representative example is a solar power generation facility that converts collected sunlight into electrical energy and supplies it.
  • MPPT maximum power tracking
  • One of the conventional MPPT algorithms is the P&O (Perturbation & Observation) algorithm set in solar inverters.
  • the P&O algorithm is a method of tracking the maximum point of the P-V curve (power-voltage curve) by gradually reducing or increasing the output voltage of the solar array and comparing the before and after power values.
  • the existing P&O algorithm has a problem in that, as the number of maximum points increases, the speed and accuracy of MPPT are significantly reduced while the phenomenon of vibration increases. In other words, it is efficient in the P-V curve with one maximum point, but when it has multiple maximum points, it is difficult to determine which maximum point is the maximum power point, so the performance and results of MPPT cannot be guaranteed.
  • VOLTAGE NOISE occurs in the process of changing current or voltage, and as a result, there is a risk that duty may be controlled in the wrong direction if an error occurs in voltage measurement.
  • the present invention is intended to solve the problems of the prior art described above, and provides energy harvesting that generates maximum power at all times by achieving fast and accurate MPPT through a DC-DC converter of a double loop circuit with different operating bandwidth. The purpose is to do so.
  • the DC-DC converter is each connected to a plurality of energy generation modules that collect external energy and convert it into electrical energy, It adjusts the voltage level of direct current power provided from the energy generation module, and the DC-DC converter includes: a buck converter; a main loop circuit that controls the duty ratio of the buck converter so that the input voltage applied to the buck converter is maintained constant; and an auxiliary loop circuit that guides the input voltage of the main loop circuit to become the maximum power voltage, where the maximum power voltage is a voltage value that allows the energy harvesting system to generate energy at maximum power.
  • the auxiliary loop circuit calculates the power of the output stage of the buck converter by calculating based on at least one of the input voltage, input current pair, output voltage, and output current pair of the buck converter.
  • power calculation unit When a current change occurs through load adjustment of the output stage of the buck converter, the N-1th output stage power before the current change occurs (N is a natural number greater than 1) and the Nth output stage power after the current change occurs.
  • a power difference calculation unit that calculates the power difference between the two; and a reference voltage correction unit that generates a first correction value based on the power difference and reflects the first correction value in the reference voltage applied to the main loop circuit.
  • the reference voltage correction unit adds or subtracts the first correction value to the reference voltage so that the power of the output terminal reaches the maximum power.
  • the first correction value applied to the Nth plus or The minus operator sign is maintained as is in the N+1th output stage, and the Nth output stage power is greater than the N-1th output stage power, but if the N+1th output stage power is less than the Nth output stage power, the 1st output stage applied to the Nth The operation sign opposite to the plus or minus operation sign of the correction value is applied to the N+1th operation.
  • the auxiliary loop circuit determines the Nth reference voltage by plus or minus the first correction value to the N-1th reference voltage, and provides the Nth reference voltage to the main loop circuit. .
  • the main loop circuit includes: an arithmetic unit that calculates a difference between the reference voltage and the input voltage of the buck converter; and a duty ratio control unit that calculates a second correction value based on the difference between the reference voltage and the input voltage and controls the duty ratio of the buck converter based on the second correction value.
  • the calculation of the second correction value is performed so that when the input voltage is lower than the previous input voltage, the duty ratio is lower than the previous input voltage, so that the input voltage is greater than the previous input voltage.
  • the duty ratio is performed so that it is greater than the previous duty ratio, so that the input voltage is maintained constant.
  • the DC-DC converter calculates the Nth reference voltage by reflecting the second correction value for the N-1th reference voltage through a feedback loop, thereby reducing the input voltage. This is to prevent separation between and the reference voltage.
  • the main loop cycle is a one-time process in which the main loop circuit calculates the difference between the reference voltage and the input voltage of the buck converter and controls the duty ratio of the buck converter.
  • the auxiliary loop circuit calculates a power difference value according to the power change of the output terminal of the buck converter and corrects the reference voltage based on the power difference value
  • the main loop cycle is executed multiple times, the auxiliary loop cycle is executed once.
  • the MPPT direction is determined only according to whether the power increases or decreases, not the direction of the increase or decrease of the voltage.
  • the maximum power point can be found more quickly and accurately, and it is easy to deal with the occurrence of vibration or noise.
  • the input voltage of the DC-DC converter is fixed and the output power is maintained, so the voltage does not drop sharply no matter what current is required within the limit capacity.
  • the MPPT algorithm is designed as a double loop operation, and the cycle of the loop to maintain the input voltage is set faster than the cycle of the loop to find the maximum power point.
  • energy at maximum power is stably provided at all times through energy harvesting.
  • FIG. 1 is a schematic structural diagram of an energy harvesting system according to an embodiment of the present invention.
  • Figure 2 is a schematic structural diagram of a DC-DC converter according to an embodiment of the present invention.
  • Figure 3 is a schematic structural diagram of an auxiliary loop circuit according to an embodiment of the present invention.
  • Figure 4 is a schematic structural diagram of the main loop circuit according to an embodiment of the present invention.
  • Figure 5 is an example diagram schematically showing the operation process of the MPPT algorithm according to an embodiment of the present invention.
  • FIG. 6 is an operation flowchart of the MPPT algorithm according to an embodiment of the present invention.
  • 'part' includes a unit realized by hardware, a unit realized by software, and a unit realized using both. Additionally, one unit may be realized using two or more pieces of hardware, and two or more units may be realized using one piece of hardware.
  • ' ⁇ part' is not limited to software or hardware, and ' ⁇ part' may be configured to reside in an addressable storage medium or may be configured to reproduce one or more processors. Therefore, as an example, ' ⁇ part' refers to components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, and procedures. , subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables.
  • components and 'parts' may be combined into a smaller number of components and 'parts' or may be further separated into additional components and 'parts'. Additionally, components and 'parts' may be implemented to regenerate one or more CPUs within a device or a secure multimedia card.
  • energy harvesting system refers to equipment that harvests natural energy collected from the surroundings by converting it into electric energy, and may include both industrial and household equipment.
  • solar power generation system it can include both stand-alone and grid-connected systems.
  • Natural energy used as renewable energy in the present invention is not limited in type, such as body energy, light energy, vibration energy, heat energy, electromagnetic wave energy, gravitational energy, and potential energy, but for explanation purposes, a representative example is the solar power generation system. The description should focus on .
  • the “P-V curve (current-voltage curve)” is a piece of information representing the operating characteristics of an electronic device, and is defined as a set of graphic curves that visually show the relationship between power and voltage that occurs within a circuit. Typically, in the present invention, it is used as one of the elements that defines the electrical characteristics at the output stage of a DC-DC converter.
  • MPPT refers to a series of processes from tracking the maximum generated power to providing it within the energy harvesting system.
  • the present invention includes the process of finding the maximum point corresponding to the maximum power within the P-V curve of the DC-DC converter and maintaining the output of maximum power through this process.
  • maximum power voltage refers to a voltage value that allows energy to be generated at maximum power through energy harvesting, and is the voltage corresponding to the maximum power point (MP) tracked by MPPT. This applies to this.
  • FIG. 1 is a structural diagram of an energy harvesting system according to an embodiment of the present invention.
  • an energy harvesting system may include an energy generation module 10 and a DC-DC converter 100.
  • the energy generation module 10 is a device that collects surrounding external energy and converts it into electrical energy.
  • it may be a cell-level “solar cell” that produces electricity through the photoelectric effect.
  • the module may be a “solar panel” in which a plurality of solar cells are connected vertically and horizontally and assembled.
  • At least one or more energy generation modules 10 may be connected to each other.
  • a plurality of energy generation modules 10 may be connected in series to form an array.
  • the DC-DC converter 100 is connected to each energy generation module 10 and adjusts the voltage level of direct current power provided from them.
  • the DC-DC converter 100 can be modularized according to unit capacity and connected to each solar panel 10 installed in the system.
  • the DC-DC converter 100 converts an input voltage (V in ) into a predetermined output voltage (V out ) according to a device that transmits the generated electrical energy. For example, in the case of an independent solar power generation system, it is boosted or stepped down to a DC voltage suitable for the connected battery, or in the case of a grid-connected system, the generated power is converted into stabilized DC power to suit the power system.
  • the inverter in MPPT in the existing energy harvesting system, the maximum power point is tracked by the inverter, and the process of adjusting the output voltage of the DC-DC converter to the maximum power voltage determined through this is carried out in one cycle. Therefore, there was a restriction that the inverter had to operate within a preset frequency (e.g., 60 Hz) depending on the system connected to it. In other words, due to problems such as power factor, if the frequency is changed faster than the set frequency, there is a high possibility that the connection with the grid will be broken, making it impossible to perform MPPT with a bandwidth above a certain level.
  • a preset frequency e.g. 60 Hz
  • an embodiment of the present invention discloses a feature of a DC-DC converter 100 that performs MPPT through a separated double loop operation.
  • Figure 2 is a schematic structural diagram of a DC-DC converter according to an embodiment of the present invention.
  • the DC-DC converter 100 may include an auxiliary loop circuit 110, a main loop circuit 120, and a buck converter 130.
  • the direct current converter may be composed of a buck converter 130.
  • the buck converter 130 is a step-down converter used when a voltage lower than the input voltage is required, and is stable because it exhibits I-V characteristics without voltage divergence. Therefore, compatibility with various inverters is possible. In addition, it has the advantage of being a relatively less complex structure that can be implemented simply and manufactured at a low cost.
  • the main loop circuit 120 may be configured as a feedback loop connected to the buck converter 130 to receive input voltage (V in ) of the buck converter 130 as feedback.
  • the main loop circuit 120 calculates the difference between the voltage (V in ) applied to the input terminal of the buck converter 130 and the reference voltage (V ref ) and adjusts the duty ratio of the PWM (Pulse Width Modulation) signal to offset the difference. Adjust. That is, the main loop circuit 120 controls the duty ratio of the buck converter 130 so that the input voltage (V in ) applied to the buck converter 130 is maintained constant.
  • the cycle in which the above process is performed once is defined as the main loop cycle.
  • the reference voltage (V ref ) may be preset in the DC-DC converter 100, but the maximum power voltage (V MP ) corresponding to the maximum power point is preferable.
  • the auxiliary loop circuit 110 receives the input voltage (V in ), input current (I in ), output voltage (V out ), and output current (V in ) of the buck converter 130 as feedback. It can be composed of a feedback loop connected to the input and output terminals.
  • the auxiliary loop circuit 110 calculates a power difference value according to the power change at the output stage of the buck converter 130 using the current and voltage of the input and output terminals that are fed back. Afterwards, the reference voltage (V ref ) is corrected so that the reference voltage (V ref ) becomes the maximum power voltage (V MP ) based on the calculated value. That is, the auxiliary loop circuit 110 serves to guide the input voltage (V in ) of the main loop circuit 120 to become the maximum power voltage (V MP ).
  • a cycle in which the above process is performed once is defined as an auxiliary loop cycle.
  • a voltage (V out ) or a current (I out ) according to the duty ratio change is applied to the output terminal of the buck converter 130.
  • V out a voltage
  • I out a current
  • the main loop cycle and the auxiliary loop cycle are designed to have different execution speeds.
  • the main loop cycle is executed multiple times (k times)
  • the auxiliary loop cycle is executed once, and the main loop can be designed to operate relatively quickly at a ratio of k:1 (k>1).
  • each loop operates at a different bandwidth, ensuring loop stability and implementing fast MPPT with relaxed frequency constraints. As a result, it is possible to respond to unexpected situations such as sudden changes in the amount of sunlight incident, contributing to the construction of a stable system.
  • Figure 3 is a schematic structural diagram of an auxiliary loop circuit according to an embodiment of the present invention.
  • the auxiliary loop circuit 110 may include a power calculation unit 111, a power difference calculation unit 112, and a reference voltage correction unit 113.
  • the power calculation unit 111 calculates the power of the output stage of the buck converter 130 and transfers it to the power difference calculation unit 112, and the power difference calculation unit 112 calculates the received output stage power and the previous output stage power.
  • the difference is calculated and transmitted to the reference voltage correction unit 113, and the reference voltage correction section 113 corrects the reference voltage applied to the main loop circuit 120 to the current maximum power voltage based on the received power difference. do.
  • the power calculation unit 111 is configured to calculate at least one of the input voltage (V in ), input current (I in ), output voltage (V out ), and output current (V in ) fed back from the buck converter 130. It may be a type of power calculator that calculates the power of the output stage of the buck converter 130 by using two or more measured values.
  • the power calculation unit 111 generates output power based on at least one of the input voltage (V in ) and input current (I in ) pairs and the output voltage (V out ) and output current (V in ) pairs. can be calculated. That is, the power calculated by the power calculation unit 111 may be the product of the input voltage (V in ) and the input current (I in ) or the product of the output voltage (V out ) and the output current (V in ).
  • the law of energy conservation is satisfied, and even if there is some power loss during the direct current conversion process, it can be excluded as it is within the error range.
  • the power calculation unit 111 may calculate the output power of the buck converter 130 at least once during the auxiliary loop cycle.
  • high reliability of MPPT can be secured by deriving the output power using the current and voltage of the input and output terminals measured several times.
  • the power calculation unit 111 may calculate the average value of the output power calculated during the auxiliary loop cycle. In this case, the influence of noise that may occur when current and voltage values are measured or when the measured values are converted to analog-to-digital can be minimized.
  • the power difference calculation unit 112 calculates the power difference between the previously stored N-1th output stage power and the Nth output stage power received from the power calculation unit 111.
  • N is a natural number greater than 1.
  • the power difference calculation unit 112 when a current change occurs through load adjustment connected to the output terminal of the buck converter 130, the N-1th output terminal power and current change occur before the current change occurs. Calculate the power difference between the power of the Nth output stage.
  • the reference voltage correction unit 113 generates a first correction value based on the power difference received from the power difference calculation unit 112 and applies the reference voltage (V) to the main loop circuit 120.
  • ref ) reflects the first correction value.
  • the first correction value is a value that corrects the reference voltage (V ref ) so that the reference voltage (V ref ) approaches the maximum power voltage.
  • the first correction value is plus or minus the N-1th reference voltage through the auxiliary loop circuit 110 to determine the Nth reference voltage, which is provided to the main loop circuit 120.
  • the reference voltage correction unit 113 calculates the reference voltage by adding or subtracting the first correction value to the previous reference voltage so that the output power of the buck converter 130 reaches the currently tracked maximum power.
  • the voltage (V ref ) is stored as the currently tracked maximum power voltage and transmitted to the main loop circuit 120.
  • V ref the reference voltage (V ref ) is continuously maintained close to the maximum power voltage due to tracking of the maximum power point on the auxiliary loop circuit 110, which means that the input voltage (V in ) in the main loop circuit 120 is the maximum power. It guides you to follow the voltage, and related details will be described later using FIG. 4.
  • the sign of the first correction value during calculation is based on the power difference received from the power difference calculation unit 112, and determines whether the output stage power increases or decreases, or whether there is a change in the increase or decrease flow of the output stage power. Depending on this, it is determined as a plus sign (+) or minus sign (-).
  • the control applied to the Nth is maintained as is for the N+1th time.
  • the operation code remains the same.
  • the control applied to the Nth output stage is 1
  • the operation sign opposite to the plus or minus operation sign of the correction value is applied to the N+1th.
  • the tracking direction is determined solely based on the change in power, not the increase or decrease in voltage. Therefore, even if there are multiple maximum points in the P-V curve, the phenomenon of progressing in the wrong direction does not occur, and the maximum power point can be accurately found without being affected by vibration or noise.
  • Figure 4 is a schematic structural diagram of the main loop circuit according to an embodiment of the present invention.
  • the main loop circuit 120 may include an operation unit 121 and a duty ratio control unit 122.
  • the calculation unit 121 calculates the difference between the reference voltage received from the auxiliary loop circuit 110 and the input voltage of the buck converter 130, and the duty ratio control unit 122 adjusts the duty ratio of the PWM to offset this difference. By controlling, the input voltage is maintained at the reference voltage.
  • the calculation unit 121 calculates the difference between the currently measured input voltage (V in ) and the currently set reference voltage (V ref ). That is, how far the current input voltage (V in ) is from the maximum power voltage, which is the reference voltage (V ref ), is determined and transmitted to the duty ratio control unit 122 .
  • the duty ratio control unit 122 calculates the second correction value based on the difference received from the calculation unit 121.
  • the second correction value may mean a duty ratio control value for correcting the input voltage (V in ) so that the input voltage (V in ) reaches the reference voltage (V ref ).
  • the duty ratio control unit 122 controls the duty ratio for the PWM signal of the buck converter 130 based on the second correction value.
  • the calculation for the second correction value is such that when the current input voltage (V in ) is lower than the previous input voltage, the current input voltage (V in ) is lower than the previous input voltage so that the current duty ratio is smaller than the previous duty ratio. If it is greater than the voltage, it can be performed so that the current duty ratio is greater than the previous duty ratio.
  • the duty ratio control unit 122 increases the duty ratio to decrease the input voltage (V in ) when it increases, and performs control to reduce the duty ratio to increase it when the input voltage (V in ) decreases. Accordingly, the input voltage can be kept constant by being fixed to the reference voltage (V ref ), which is the currently tracked maximum power voltage.
  • the current flowing to the input terminal is also fixed. Accordingly, the power generated at the input terminal of the buck converter 130 is also fixed to a constant level.
  • the power at the input terminal and the power at the output terminal in the buck converter 130 are the same, so the power at the output terminal is also fixed to a constant. Since power is the product of current and voltage, when power is fixed, an inverse relationship is established with the output current (I out ) for the output voltage (V out ) below the reference voltage (V ref ). In other words, instead of the conventional non-linear IV characteristic, it is converted to a linear IV characteristic in which the voltage applied to the output stage decreases when the current flowing through the output stage increases.
  • the DC-DC converter 100 can be stably driven no matter how much current flows as long as it is within the limit capacity of the circuit.
  • the current and voltage at the output terminal of the buck converter 130 have an inverse relationship below the reference voltage (V ref ), so the PV curve below the reference voltage (V ref ) has a gentle slope.
  • V ref reference voltage
  • the reference voltage (V ref ) is the maximum power voltage (V MP ) provided from the auxiliary loop circuit 110, and the slope of the PV curve below the reference voltage (V ref ) is used to maintain maximum power. is preferably designed to be “0”.
  • the voltage (V out ) applied to the output terminal of the buck converter 130 is a voltage lower than the reference voltage (V ref ). Therefore, according to the above-described embodiment, since the PV curve is saturated below the reference voltage (V ref ), the maximum power output can be maintained at all times to achieve maximum efficiency of energy harvesting.
  • the main loop cycle can be designed faster than the auxiliary loop cycle at a ratio of k:1.
  • the main loop operates with a faster bandwidth than the auxiliary loop.
  • the ratio is 5:1
  • the loop that keeps the input voltage (V in ) constant at the maximum power voltage during the auxiliary loop cycle operates 5 times faster. Therefore, even if the current is suddenly pulled at the output terminal or the power at the input terminal is suddenly reduced, the maximum power voltage is maintained constant, so a sudden deviation from the maximum power does not occur.
  • MPPT can be performed at a significantly faster speed than before, and at the same time can maintain accurate maximum power output.
  • the DC-DC converter 100 may further include a feedback loop that prevents separation between the input voltage (V in ) and the reference voltage (V ref ).
  • the main loop circuit 120 may transmit the second correction value calculated based on the N-1th reference voltage to the auxiliary loop circuit 120.
  • the auxiliary loop circuit 120 performs correction to reflect the received second correction value to the N-th reference voltage by adding or subtracting the second correction value. can do. In this way, even in an unexpected situation where the input power suddenly changes due to internal or external causes, the input voltage (V in ) is not too far from the reference voltage (V ref ), preventing an error in which the MPPT proceeds in the wrong direction. there is.
  • FIG. 5 is an example diagram schematically showing the operation process of the MPPT algorithm according to an embodiment of the present invention
  • FIG. 6 is an operation flowchart of the MPPT algorithm according to an embodiment of the present invention.
  • steps S61 to S65 are a process of finding the maximum power point and are performed every auxiliary loop cycle
  • step S66 is a process of fixing the voltage applied to the input terminal of the buck converter to the maximum power voltage derived in step S65 and are performed every main loop cycle.
  • the main loop cycle can operate multiple times (k, k is a number greater than 1). In other words, the main loop cycle can be designed with a faster bandwidth than the auxiliary loop cycle.
  • step S65 the maximum power voltage determined in step S65 is the N-1th maximum power voltage
  • the loop that fixes the input voltage to the N-1th maximum power voltage through step S66 operates k times
  • the Nth maximum power voltage is simultaneously maintained.
  • the tracking loop operates once.
  • step S61 at least two of the input voltage (adc_V in ), output voltage (adc_V out ), input current (adc_I in ), and output current (adc_I out ) of the buck converter are measured. For example, at least one of a pair of voltage (adc_V in ) and current (adc_I in ) at the input terminal and a pair of voltage (adc_V out ) and current (adc_I out ) at the output terminal is measured.
  • step S62 the power of the buck converter output stage is calculated. An operation is performed to multiply the voltage (adc_V in ) and current (adc_I in ) of the input terminal or the voltage (adc_V out ) and current (adc_I out ) of the output terminal. At this time, a plurality of powers can be calculated through various measurement values collected during the auxiliary loop cycle, and ultimately step S63 can be performed using the average value of these values.
  • a first correction value (err_s) is calculated based on the calculated power (power).
  • the first correction value (err_s) is calculated based on the change rate of power (power). For example, when there is an adjustment of the load, the rate of change between the power before adjustment and the power after adjustment is calculated, and the voltage value required to reach the power after adjustment is calculated based on the P-V curve.
  • step S64 the operation sign (sign) of the first correction value (err_s) is determined. In other words, it is determined whether the first correction value should be plus or minus in order to reach the maximum power point on the P-V curve. At this time, when the rising or falling flow of power is maintained, the sign of the first correction value is determined as calculated. On the other hand, when the flow of power changes, the sign of the first correction value changes to the opposite of the calculated state.
  • step S65 the reference voltage (adc_V ref ) corresponding to the current maximum power voltage is determined by reflecting the first correction value (err_s).
  • the first correction value (err_s) can be integrated into the previous reference voltage based on the operation sign (sign), and a preset integration constant (K I ) can be applied.
  • step S66 the difference between the reference voltage (adc_V ref ) determined in step S66 and the voltage (adc_V in ) measured at the input terminal of the buck converter is calculated.
  • a second correction value (err_p) is calculated for the input voltage (adc_V in ) to reach the reference voltage (adc_V ref ).
  • the second correction value (err_p) can be integrated into the input voltage (adc_V in ), and a preset integration constant (K I ) or proportional constant (K P ) can be applied.
  • duty ratio control is performed based on the second correction value (err_p), and accordingly, the input voltage (adc_V in ) is fixed to the reference voltage (adc_V ref ) to maintain output of maximum power.
  • step S66 in order to prevent a large gap between the input voltage (adc_V in ) and the reference voltage (adc_V ref ), the second correction value (err_p) for the N-1th reference voltage is reflected and the Nth A reference voltage can be calculated.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

Un convertisseur CC-CC d'un système de collecte d'énergie selon un mode de réalisation de la présente invention est connecté à une pluralité de modules de génération d'énergie qui collectent et convertissent l'énergie externe en énergie électrique, et régule le niveau de tension fourni par les modules de génération d'énergie, le convertisseur CC-CC comprenant : un convertisseur abaisseur de tension ; un circuit de boucle principale permettant de réguler le rapport cyclique du convertisseur abaisseur de sorte que la tension d'entrée appliquée à ce dernier puisse être maintenue à un niveau défini ; et un circuit de boucle auxiliaire permettant de guider la tension d'entrée du circuit de boucle principale pour atteindre la tension de puissance maximale, la tension de puissance maximale étant la valeur de tension à laquelle le système de collecte d'énergie peut générer de l'énergie à la puissance maximale.
PCT/KR2022/013883 2022-06-13 2022-09-16 Algorithme de suivi de point de puissance maximale à boucles doubles séparées, et convertisseur cc-cc pour son exécution WO2023243770A1 (fr)

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KR1020220071272A KR102566205B1 (ko) 2022-06-13 2022-06-13 분리된 이중 루프로 동작하는 최대전력 추종 알고리즘 및 이를 수행하는 직류 변환 장치

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Citations (5)

* Cited by examiner, † Cited by third party
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US8773077B1 (en) * 2010-03-05 2014-07-08 University Of Central Florida Research Foundation, Inc. Controllers for battery chargers and battery chargers therefrom
KR20150106771A (ko) * 2014-03-12 2015-09-22 삼성전자주식회사 승압 회로를 제어하는 방법 및 장치, 그리고 이를 이용한 최대 전력 추출 장치
KR101643817B1 (ko) * 2014-10-07 2016-07-28 서울시립대학교 산학협력단 에너지 하베스팅 시스템의 최대 전력점 구동 장치
US10396590B2 (en) * 2011-03-22 2019-08-27 Triune Systems, LLC Variable power energy harvesting system
KR102312805B1 (ko) * 2020-05-29 2021-10-15 주식회사 스카이칩스 에너지 하베스팅 시스템에서의 최대 전력 지점 추적 장치 및 그 제어 방법

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8773077B1 (en) * 2010-03-05 2014-07-08 University Of Central Florida Research Foundation, Inc. Controllers for battery chargers and battery chargers therefrom
US10396590B2 (en) * 2011-03-22 2019-08-27 Triune Systems, LLC Variable power energy harvesting system
KR20150106771A (ko) * 2014-03-12 2015-09-22 삼성전자주식회사 승압 회로를 제어하는 방법 및 장치, 그리고 이를 이용한 최대 전력 추출 장치
KR101643817B1 (ko) * 2014-10-07 2016-07-28 서울시립대학교 산학협력단 에너지 하베스팅 시스템의 최대 전력점 구동 장치
KR102312805B1 (ko) * 2020-05-29 2021-10-15 주식회사 스카이칩스 에너지 하베스팅 시스템에서의 최대 전력 지점 추적 장치 및 그 제어 방법

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