DC-DC circuit photovoltaic input MPPT method and device

Abstract

The invention relates to the field of photovoltaic technology, and discloses a DC-DC circuit photovoltaic input MPPT method and device, and the method comprises the steps: calculating the output power of a DC-DC circuit at the current moment, comparing the output power at the current moment with the reference power at the current moment, and determining the output power of the DC-DC circuit at the current moment; the disturbance voltage at the current moment is obtained based on the power comparison result, and the reference power at the next moment is updated; and comparing the disturbance voltage at the current moment with the input voltage of the DC-DC circuit at the current moment, and controlling the duty ratio of a power switch device in the DC-DC circuit based on a voltage comparison result. The reference power of the next moment is dynamically adjusted through the output power of the current moment and the reference power of the current moment, meanwhile, the disturbance voltage is determined based on the output power of the current moment and the reference power of the current moment, and the disturbance voltage can disturb the input voltage, so that the disturbance voltage is more stable. The maximum photovoltaic power point is tracked simply and quickly, and hardware DC-DC MPPT tracking is achieved.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a DC-DC circuit photovoltaic input MPPT method and device. Background Art

[0002] Faced with the increasing depletion of fossil energy and environmental pollution, low-carbon, clean and renewable energy represented by solar energy has been vigorously developed. With the continuous innovation of power electronic devices, DC boost grid-connected technology has become increasingly mature, making it possible for large-scale photovoltaic power stations to adopt DC boost collection access systems. Photovoltaic cells and DC DC circuits are key equipment for energy conversion and DC boost. It is of great research significance to ensure the efficient and stable operation of the system through the cooperation of the two.

[0003] Hardware DC-DC circuits are widely used. However, when connecting solar panels, the input voltage needs to be adjusted at any time to track the maximum power point (MPPT) to obtain maximum power. However, hardware DC-DC circuits cannot automatically adjust the input voltage to achieve MPPT tracking. Summary of the invention

[0004] In view of this, the present invention provides a DC-DC circuit photovoltaic input MPPT method and device to solve the problem that the hardware DC-DC circuit cannot automatically adjust the input voltage and achieve MPPT tracking.

[0005] In a first aspect, the present invention provides a DC-DC circuit photovoltaic input MPPT method, comprising: calculating the output power of the DC-DC circuit at the current moment, and comparing the output power at the current moment with the reference power at the current moment, and obtaining the disturbance voltage at the current moment and updating the reference power at the next moment based on the power comparison result; comparing the disturbance voltage at the current moment with the input voltage of the DC-DC circuit at the current moment, and controlling the duty cycle of the power switching device inside the DC-DC circuit based on the voltage comparison result.

[0006] The present invention dynamically adjusts the reference power at the next moment through the output power at the current moment and the reference power at the current moment, and determines the disturbance voltage based on the output power at the current moment and the reference power at the current moment. The disturbance voltage can disturb the input voltage to simply and quickly track the photovoltaic maximum power point and realize hardware DC-DC MPPT tracking.

[0007] In an optional implementation, when the DC-DC circuit is just powered on, the disturbance voltage at the first moment is a preset multiple of the input voltage at the first moment, and the preset multiple is less than 1.

[0008] In an optional embodiment, the process of updating the reference power at the next moment includes: when the output power at the current moment is greater than the reference power at the current moment, the output power at the current moment is used as the reference power at the next moment; when the output power at the current moment is less than the reference power at the current moment, the preset maximum power point at the current moment is used as the reference power at the next moment.

[0009] The present invention compares the output powers at two adjacent moments and uses the larger output power as the reference power at the next moment, that is, dynamically adjusts the reference power. Compared with the fixed reference power, a smaller power difference can determine the disturbance voltage adjustment, and the output power at the next moment can be adjusted relatively quickly.

[0010] In an optional embodiment, the process of obtaining the disturbance voltage at the current moment includes: when the output power at the current moment is greater than the reference power at the current moment, the disturbance voltage at the previous moment is increased by a first preset voltage difference and used as the disturbance voltage at the current moment; when the output power at the current moment is less than the reference power at the current moment, the disturbance voltage at the previous moment is reduced by a second preset voltage difference and used as the disturbance voltage at the current moment.

[0011] The present invention determines whether the disturbance voltage needs to be modified according to the output power and the reference power, that is, the disturbance voltage and the reference power are also dynamic. Therefore, compared with a fixed disturbance voltage, the input voltage can be adjusted quickly and MPPT can be realized.

[0012] In an optional embodiment, the process of controlling the duty cycle of the power switching device inside the DC-DC circuit based on the voltage comparison result includes: when the disturbance voltage at the current moment is greater than the input voltage of the DC-DC circuit at the current moment, controlling the duty cycle of the power switching device inside the DC-DC circuit based on the input voltage and output voltage at the current moment.

[0013] The present invention adds a disturbance voltage mode to the existing duty cycle control method of the power switch device of the DC-DC circuit, thereby solving the problem that the hardware DC-DC circuit cannot automatically adjust the input voltage, and at the same time quickly realizes MPPT.

[0014] In the second aspect, the present invention provides a DC-DC circuit photovoltaic input MPPT device, a voltage disturbance module, and a control module, wherein the voltage disturbance module is used to calculate the output power of the DC-DC circuit at the current moment, and compare the output power at the current moment with the reference power at the current moment, and output the disturbance voltage at the current moment based on the power comparison result; the control module is used to compare the disturbance voltage at the current moment with the input voltage of the DC-DC circuit at the current moment, and control the duty cycle of the power switching device inside the DC-DC circuit based on the voltage comparison result.

[0015] The voltage disturbance module of the present invention dynamically adjusts the reference power at the next moment through the output power at the current moment and the reference power at the current moment, and determines the disturbance voltage based on the output power at the current moment and the reference power at the current moment. The disturbance voltage can disturb the input voltage so that the control module can simply and quickly track the photovoltaic maximum power point and realize hardware DC-DC MPPT tracking.

[0016] In an optional embodiment, the voltage disturbance module includes: a sampling circuit, a microcontroller unit and a digital-to-analog conversion circuit, wherein the sampling circuit is used to obtain the input voltage and output voltage of the DC-DC circuit at the current moment; the microcontroller unit is used to calculate the output power at the current moment based on the output voltage and output current of the DC-DC circuit, and compare the output power at the current moment with the reference power at the current moment, and output the disturbance voltage at the current moment based on the power comparison result; the digital-to-analog conversion circuit is used to convert the disturbance voltage at the current moment of the digital quantity into an analog quantity and output it to the control module.

[0017] In an optional embodiment, when the microcontroller unit determines that the output power at the current moment is greater than the reference power at the current moment, the microcontroller unit increases the disturbance voltage at the previous moment by a first preset voltage difference and uses it as the disturbance voltage at the current moment; when the microcontroller unit determines that the output power at the current moment is less than the reference power at the current moment, the microcontroller unit reduces the disturbance voltage at the previous moment by a second preset voltage difference and uses it as the disturbance voltage at the current moment.

[0018] In an optional embodiment, the control module is used to control the duty cycle of the power switching device inside the DC-DC circuit based on the input voltage and output voltage at the current moment when the disturbance voltage at the current moment is greater than the input voltage of the DC-DC circuit at the current moment.

[0019] In an optional implementation, the DC-DC circuit photovoltaic input MPPT device further includes: a power supply, wherein the power supply is used to supply power to the voltage disturbance module and the control module. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 is a flow chart of a DC-DC circuit photovoltaic input MPPT method according to an embodiment of the present invention;

[0022] Figure 2 is a schematic diagram of a process of updating a reference power at the next moment according to an embodiment of the present invention;

[0023] Figure 3 is a schematic diagram of a flow chart of obtaining a disturbance voltage at a current moment according to an embodiment of the present invention;

[0024] Figure 4 is a structural block diagram of a DC-DC circuit photovoltaic input MPPT device according to an embodiment of the present invention;

[0025] Figure 5 is a circuit structure diagram of a bidirectional BUCK-BOOST circuit according to an embodiment of the present invention;

[0026] Figure 6 is a circuit structure diagram of another bidirectional BUCK-BOOST circuit according to an embodiment of the present invention;

[0027] Figure 7 is a specific circuit structure diagram of a micro control unit according to an embodiment of the present invention;

[0028] Figure 8 is a specific circuit structure diagram of a sampling circuit according to an embodiment of the present invention;

[0029] Fig. 9 is a specific circuit structure diagram of a digital-to-analog conversion circuit and a comparison circuit according to an embodiment of the present invention;

[0030] Fig.10 is a specific circuit structure diagram of a control chip according to an embodiment of the present invention;

[0031] Fig.11 is a specific circuit structure diagram of a power supply according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0033] The patent with the related technology application number CN202210869307.X realizes the distributed control method of single-phase CHB photovoltaic inverter for MPPT, which belongs to the inverter system, has complex algorithms, high hardware requirements, and requires a special DSP chip. The patent with the application number CN202310859611.0 introduces a photovoltaic power generation processing method for optimizing MPPT, which is characterized by the need to obtain the initial data of photovoltaic power generation equipment in advance, including the initial data of PV components, DPP converters and DC-DC converters. And based on the initial data, the target main string current value is obtained, and then the maximum power point of the photovoltaic power generation equipment is tracked according to the target main string current value. However, neither of these two patents can achieve maximum power point tracking by adjusting the input voltage in real time.

[0034] Based on this, in order to solve the problems in the related art, according to an embodiment of the present invention, a DC-DC circuit photovoltaic input MPPT method embodiment is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0035] In this embodiment, a DC-DC circuit photovoltaic input MPPT method is provided, such as Figure 1 As shown, including:

[0036] Step S1: Calculate the output power of the DC-DC circuit at the current moment, and compare the output power at the current moment with the reference power at the current moment, and obtain the disturbance voltage at the current moment and update the reference power at the next moment based on the power comparison result.

[0037] Specifically, the disturbance voltage is adjusted based on the output power at the current moment, and the disturbance voltage is compared with the input voltage to determine whether the duty cycle of the power switch device inside the DC-DC circuit needs to be adjusted.

[0038] Specifically, since the output powers at two adjacent moments are the same or different, and the photovoltaic maximum power point is tracked simply and quickly, a dynamic reference power is set, and the reference power is determined by the output power at the current moment and the reference power at the current moment.

[0039] Step S2: Compare the disturbance voltage at the current moment with the input voltage of the DC-DC circuit at the current moment, and control the duty cycle of the power switch device inside the DC-DC circuit based on the voltage comparison result.

[0040] Specifically, the disturbance voltage at the current moment is compared with the input voltage at the current moment. When the disturbance voltage at the current moment is greater than the input voltage at the current moment, it indicates that the output power at the current moment has not reached the maximum power point, and thus the duty cycle of the power switch device inside the DC-DC circuit needs to be adjusted.

[0041] The present invention dynamically adjusts the reference power at the next moment based on the output power and the reference power at the current moment. Meanwhile, based on the output power and the reference power at the current moment, the disturbance voltage is determined, and this disturbance voltage can disturb the input voltage to simply and quickly track the photovoltaic maximum power point and achieve hardware DC-DC MPPT tracking.

[0042] In some optional embodiments, when the DC-DC circuit is just powered on, the disturbance voltage at the first moment is a preset multiple of the input voltage at the first moment, and the preset multiple is less than 1. Optionally, the preset multiple is a proportionality coefficient. Considering the maximum power value of a general photovoltaic panel, the preset multiple can be taken to be about 0.8 times.

[0043] In some optional embodiments, as Figure 2 shown, the process of updating the reference power at the next moment includes:

[0044] Step S101: When the output power at the current moment is greater than the reference power at the current moment, the output power at the current moment is used as the reference power at the next moment.

[0045] Step S102: When the output power at the current moment is less than the reference power at the current moment, the preset maximum power point at the current moment is used as the reference power at the next moment.

[0046] Specifically, taking two moments as an example, the output power at the first moment is P1, the output power at the second moment is P2, the reference power at the second moment is P0, and the current moment is the second moment. Then, if P1 > P2, P1 is used as the reference power P0 at the third moment; if P1 < P2, P2 is used as the reference power P0 at the third moment.

[0047] The present invention compares the output powers at two adjacent moments and uses the larger output power as the reference power at the next moment, that is, dynamically adjusts the reference power. Compared with a fixed reference power, a smaller power difference can be used to determine the disturbance voltage adjustment, and the output power at the next moment can be adjusted relatively quickly.

[0048] In some optional embodiments, as Figure 3 shown, the process of obtaining the disturbance voltage at the current moment includes:

[0049] Step S111: when the output power at the current moment is greater than the reference power at the current moment, the disturbance voltage at the previous moment is increased by a first preset voltage difference to be used as the disturbance voltage at the current moment.

[0050] Step S112: when the output power at the current moment is less than the reference power at the current moment, the disturbance voltage at the previous moment is reduced by a second preset voltage difference to be used as the disturbance voltage at the current moment.

[0051] Specifically, the disturbance voltage at the first moment is a preset multiple of the voltage corresponding to the maximum power point, wherein the preset multiple is less than 1, and the preset multiple can be taken as 0.8. When the output power at the second moment is greater than the reference power at the current moment, it means that the output power of the DC-DC circuit increases from the first moment to the second moment, and whether the output power of the DC-DC circuit is the maximum power point, the disturbance voltage needs to be further increased. If at the third moment, the disturbance voltage causes the output power at the third moment to further increase, the disturbance voltage needs to be increased again. If at the third moment, the disturbance voltage causes the output power at the third moment to decrease, it means that the output power at the second moment is closer to the maximum power point, so the disturbance voltage can be relatively reduced, and so on, so as to realize MPPT.

[0052] In some optional embodiments, the process of controlling the duty cycle of the power switching device inside the DC-DC circuit based on the voltage comparison result includes: when the disturbance voltage at the current moment is greater than the input voltage of the DC-DC circuit at the current moment, controlling the duty cycle of the power switching device inside the DC-DC circuit based on the input voltage and output voltage at the current moment.

[0053] Specifically, when the disturbance voltage at the current moment is greater than the input voltage at the current moment, it indicates that the duty cycle of the power switching device inside the DC-DC circuit needs to be adjusted. The duty cycle is adjusted according to the preset MPPT method. The MPPT method is not limited to the constant voltage control method, the admittance increment method, etc., and is not limited here.

[0054] In this embodiment, a DC-DC circuit photovoltaic input MPPT device is provided, such as Figure 4 As shown, the DC-DC circuit photovoltaic input MPPT device includes: a voltage disturbance module, a control module, wherein the DC-DC circuit can be a BUCK circuit, a BOOST circuit, a BUCK-BOOST circuit, etc., the BUCK-BOOST circuit can be a bidirectional BUCK-BOOST circuit, and the circuit structure of the bidirectional BUCK-BOOST circuit can be Figure 5 The circuit structure shown is only an example and is not intended to be limiting.

[0055] Specifically, the voltage disturbance module is used to calculate the output power of the DC-DC circuit at the current moment, compare the output power at the current moment with the reference power at the current moment, and output the disturbance voltage at the current moment based on the power comparison result.

[0056] The voltage disturbance module adjusts the disturbance voltage based on the output power at the current moment, and the disturbance voltage is compared with the input voltage to determine whether the duty cycle of the power switch device inside the DC-DC circuit needs to be adjusted. Since the output power at two adjacent moments is the same or different, and it is simple and fast to track the photovoltaic maximum power point, a dynamic reference power is set, and the reference power is determined by the output power at the current moment and the reference power at the current moment. The voltage disturbance module specifically implements step S1, and the specific implementation method is not repeated here.

[0057] Specifically, the control module is used to compare the disturbance voltage at the current moment with the input voltage of the DC-DC circuit at the current moment, and control the duty cycle of the power switch device inside the DC-DC circuit based on the voltage comparison result.

[0058] The control module compares the disturbance voltage at the current moment with the input voltage at the current moment. When the disturbance voltage at the current moment is greater than the input voltage at the current moment, it indicates that the output power at the current moment has not reached the maximum power point, and it is necessary to adjust the duty cycle of the power switch device inside the DC-DC circuit. The voltage disturbance module specifically implements step S2, and the specific implementation method is not repeated here.

[0059] for Figure 4 The composition diagram and related specific circuit structure diagram, the MPPT method is as follows:

[0060] (1) Photovoltaic input, MCU chip power on, start the MCU chip to collect input voltage VIN, MCU chip output disturbance voltage according to VIN voltage, so that the working input voltage of hardware DC-DC circuit is a*VIN voltage, where a is the proportional coefficient. Generally, the maximum power value of photovoltaic panel can be about 0.8. At this time, the working input voltage of DCDC module is a*VIN, that is, the disturbance voltage is a*VIN.

[0061] (2) The MCU chip collects the output voltage VOUT and current IOUT of the DC-DC circuit in real time, and obtains the output power at the first moment as P1 = VOUT*IOUT.

[0062] (3) Increase the DAC value (i.e., increase the perturbation voltage value). The increase in the perturbation voltage may cause the input voltage of the DC-DC circuit to increase or decrease. At the same time, collect the output power P2 at the second moment. Compare P1 and P2. If P2 > P1, then confirm that the increased DAC value corresponds to the input voltage of the higher power. If P2 < P1, then the unchanged DAC value corresponds to the input voltage of the higher power.

[0063] In step (3), if P2 > P1, then continue to increase the DAC value and collect the output power P3 at the third moment. If P3 > P2, then update P3 to the reference power at the fourth moment. Otherwise, maintain P2 as the reference power at the fourth moment. It can be understood that the reference power is the maximum power point at the current moment.

[0064] If in step (3), P2 < P1, then the reference power at the third moment is P1. At the same time, reduce the DAC value and collect the output power P3 at the third moment. If P3 > P1, then update P3 to the reference power at the fourth moment. Otherwise, maintain P1 as the reference power at the fourth moment.

[0065] Repeat the above steps to simply and quickly track the photovoltaic maximum power point and achieve hardware DC-DC MPPT tracking.

[0066] The voltage perturbation module of the present invention dynamically adjusts the reference power at the next moment based on the output power at the current moment and the reference power at the current moment. At the same time, based on the output power at the current moment and the reference power at the current moment, determine the perturbation voltage, which can perturb the input voltage so that the control module can simply and quickly track the photovoltaic maximum power point and achieve hardware DC-DC MPPT tracking.

[0067] In some alternative embodiments, as Figure 6 shown, the voltage perturbation module includes: a sampling circuit, a micro-control unit, and a digital-to-analog conversion circuit.

[0068] Specifically, the sampling circuit is used to obtain the input voltage and output voltage of the DC-DC circuit at the current moment. Optionally, the sampling circuit can collect the input voltage and output voltage by means of resistor voltage division. The specific circuit structure of the sampling circuit can be Figure 7 the structure shown, where VIN is the input voltage, VOUT is the output voltage, and ADC4_VOL and ADC3_VOL are connected to the micro-control unit.

[0069] Specifically, the micro-control unit is used to calculate the output power at the current moment based on the output voltage and output current of the DC-DC circuit, compare the output power at the current moment with the reference power at the current moment, and output the perturbation voltage at the current moment based on the power comparison result.

[0070] Optionally, when the microcontroller unit determines that the output power at the current moment is greater than the reference power at the current moment, the microcontroller unit increases the disturbance voltage at the previous moment by a first preset voltage difference and uses it as the disturbance voltage at the current moment; when the microcontroller unit determines that the output power at the current moment is less than the reference power at the current moment, the microcontroller unit reduces the disturbance voltage at the previous moment by a second preset voltage difference and uses it as the disturbance voltage at the current moment.

[0071] Optionally, the microcontroller unit may be an MCU chip, and the specific structure is as follows: Figure 8 As shown, the MCU chip can convert the output voltage and output current of the analog word into digital quantities, and can implement steps S1, S101, S102, S111, and S112. The specific implementation method will not be repeated here.

[0072] Specifically, the digital-to-analog conversion circuit is used to convert the disturbance voltage of the current moment of the digital quantity into an analog quantity and then output it to the control module. The specific circuit structure of the digital-to-analog conversion circuit is as follows: Fig. 9 shown.

[0073] In some optional implementations, the control module is used to, when determining that the disturbance voltage at the current moment is greater than the input voltage of the DC-DC circuit at the current moment, use the ratio of the disturbance voltage at the current moment to the preset multiple as the maximum power point at the current moment; based on the maximum power point at the current moment, the input voltage and output voltage of the DC-DC circuit at the current moment, control the duty cycle of the power switch device inside the DC-DC circuit. The control module can implement step S2, and the specific implementation method will not be repeated.

[0074] Optionally, the control module includes a control chip and a comparison circuit. The specific circuit structure of the comparison circuit is as follows: Fig. 9 As shown, the structure of the control chip is as follows Fig.10 As shown, the comparison circuit can compare the disturbance voltage at the current moment with the input voltage of the DC-DC circuit at the current moment. When the disturbance voltage at the current moment is greater than the input voltage of the DC-DC circuit at the current moment, the comparison circuit outputs a high level to the control chip, and the control chip adjusts the duty cycle based on the input voltage and the output voltage.

[0075] The control module and voltage disturbance module of the present invention both use DSP chips, while the MCU controls and adjusts the DAC voltage to achieve input voltage disturbance, and simultaneously collects the voltage and current output by the DC-DC circuit, calculates the power change, and tracks the photovoltaic maximum power point.

[0076] In some optional implementations, the DC-DC circuit photovoltaic input MPPT device further includes: a power supply, wherein the power supply is used to supply power to the voltage disturbance module and the control module.

[0077] Optionally, the specific circuit structure of the power supply is as follows: Fig.11 As shown, the power supply can take power from the input end of the DC-DC circuit, and then convert the input voltage into power supply voltages of different amplitudes to power the voltage disturbance module and the control module.

[0078] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A DC-DC circuit photovoltaic input MPPT method, characterized in that: include: Calculating the output power of the DC-DC circuit at the current moment, and comparing the output power at the current moment with the reference power at the current moment, and obtaining the disturbance voltage at the current moment and updating the reference power at the next moment based on the power comparison result; The disturbance voltage at the current moment is compared with the input voltage of the DC-DC circuit at the current moment, and the duty cycle of the power switch device inside the DC-DC circuit is controlled based on the voltage comparison result.

2. The DC-DC circuit photovoltaic input MPPT method according to claim 1, characterized in that: When the DC-DC circuit is just powered on, the disturbance voltage at a first moment is a preset multiple of the input voltage at the first moment, and the preset multiple is less than 1.

3. The DC-DC circuit photovoltaic input MPPT method according to claim 1, characterized in that: The process of updating the reference power at the next moment includes: When the output power at the current moment is greater than the reference power at the current moment, the output power at the current moment is used as the reference power at the next moment; When the output power at the current moment is less than the reference power at the current moment, the preset maximum power point at the current moment is used as the reference power at the next moment.

4. The DC-DC circuit photovoltaic input MPPT method according to claim 1, characterized in that: The process of obtaining the disturbance voltage at the current moment includes: When the output power at the current moment is greater than the reference power at the current moment, the disturbance voltage at the previous moment is increased by the first preset voltage difference as the disturbance voltage at the current moment; When the output power at the current moment is less than the reference power at the current moment, the disturbance voltage at the previous moment is reduced by a second preset voltage difference and used as the disturbance voltage at the current moment.

5. The DC-DC circuit photovoltaic input MPPT method according to claim 1, characterized in that: The process of controlling the duty cycle of the power switch device inside the DC-DC circuit based on the voltage comparison result includes: When the disturbance voltage at the current moment is greater than the input voltage of the DC-DC circuit at the current moment, the duty cycle of the power switch device inside the DC-DC circuit is controlled based on the input voltage and output voltage at the current moment.

6. A DC-DC circuit photovoltaic input MPPT device, characterized in that: Voltage disturbance module, control module, wherein: The voltage disturbance module is used to calculate the output power of the DC-DC circuit at the current moment, compare the output power at the current moment with the reference power at the current moment, and output the disturbance voltage at the current moment based on the power comparison result; The control module is used to compare the disturbance voltage at the current moment with the input voltage of the DC-DC circuit at the current moment, and control the duty cycle of the power switch device inside the DC-DC circuit based on the voltage comparison result.

7. The DC-DC circuit photovoltaic input MPPT device according to claim 6, characterized in that: The voltage disturbance module includes: a sampling circuit, a micro control unit and a digital-to-analog conversion circuit, wherein: The sampling circuit is used to obtain the input voltage and output voltage of the DC-DC circuit at the current moment; The micro control unit is used to calculate the output power at the current moment based on the output voltage and output current of the DC-DC circuit, compare the output power at the current moment with the reference power at the current moment, and output the disturbance voltage at the current moment based on the power comparison result; The digital-to-analog conversion circuit is used to convert the disturbance voltage of the digital quantity at the current moment into an analog quantity and then output it to the control module.

8. The DC-DC circuit photovoltaic input MPPT device according to claim 7, characterized in that: When the micro control unit determines that the output power at the current moment is greater than the reference power at the current moment, the micro control unit increases the disturbance voltage at the previous moment by a first preset voltage difference as the disturbance voltage at the current moment; When the micro control unit determines that the output power at the current moment is less than the reference power at the current moment, the micro control unit reduces the disturbance voltage at the previous moment by a second preset voltage difference as the disturbance voltage at the current moment.

9. The DC-DC circuit photovoltaic input MPPT device according to claim 6, characterized in that: The control module is used to control the duty cycle of the power switch device inside the DC-DC circuit based on the input voltage and output voltage at the current moment when the disturbance voltage at the current moment is greater than the input voltage of the DC-DC circuit at the current moment.

10. The DC-DC circuit photovoltaic input MPPT device according to claim 6, characterized in that: Also includes: Power supply, where: The power supply is used to supply power to the voltage disturbance module and the control module.

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