A maximum power control method and control device for photovoltaic micro inverter

Abstract

The present invention provides a maximum power control method and control device for a photovoltaic micro-inverter, the method comprising: obtaining the output voltage and output current of a photovoltaic module; when the output voltage of the photovoltaic module is greater than or equal to a first voltage threshold, the controller runs an MPPT algorithm to calculate the maximum power point voltage and / or maximum power point current corresponding to the maximum output power of the photovoltaic module based on the output voltage and output current of the photovoltaic module; when the maximum power point voltage is greater than or equal to a preset second voltage threshold, the controller runs an MPPT algorithm to make the photovoltaic module work at the maximum power point voltage or the maximum power point current; otherwise, the controller runs a starting point control method to make the photovoltaic module work at the second voltage threshold or the threshold current corresponding to the second voltage threshold. By not using MPPT control in the low-voltage section but using the starting point control method, the power generation of the low-voltage section is effectively utilized, thereby increasing the power generation of the photovoltaic micro-inverter.

Description

Technical Field

[0001] The present invention relates to the technical field of inverter control, and in particular to a maximum power control method and a control device for a photovoltaic micro inverter. Background Art

[0002] A microinverter is an inverter that is directly connected to one or more photovoltaic modules. Each photovoltaic module is individually connected to a set of input terminals of the microinverter.

[0003] The output of photovoltaic modules has nonlinear characteristics. Light intensity and temperature changes will affect the output characteristics of photovoltaic cells. The IV curve and PV curve of typical photovoltaic modules are as follows: Figure 1 As shown, the IV curve represents the relationship between the output current and the output voltage, and the PV curve represents the relationship between the output power and the output voltage.

[0004] Maximum Power Point Tracking (MPPT) is an important technology in photovoltaic systems, which aims to enable photovoltaic panels to output electricity at maximum efficiency. The Perturb and Observe Method (P&O) tracks the maximum power point by comparing the power of photovoltaic cells at adjacent sampling points. The principle and control implementation are relatively simple, and it is the most commonly used MPPT algorithm.

[0005] The shortcomings of existing photovoltaic micro-inverter technology are: the input voltage of photovoltaic modules is very wide, with a typical value of 16 to 60V. The input voltage has a large range of variation, and the corresponding transformer ratio is also large. It is difficult to balance the wide input range and high conversion efficiency in design. Based on this, existing micro-inverters usually abandon the low voltage segment, for example, the minimum input voltage V min The design voltage is about 22-25V, and the optimal operating point is about 38-45V. This design can have a higher conversion efficiency in the medium and high voltage range, thereby achieving a higher average or weighted conversion efficiency. However, the problem with this technical solution is that the micro inverter is less than V min The maximum power point voltage V MP It is less than the threshold voltage for the inverter to start, so the inverter does not work and the output power is 0. If you want to make the most of the power generated by the photovoltaic module in the low voltage range, you should try to reduce the minimum input voltage V min, but this will lead to an increase in the circuit's step-up ratio and input voltage range. For example, the input voltage range of the photovoltaic module selected for grid-connected power generation is 20-60V, and the transformer output voltage is designed to be 360V. When the input voltage is 20V, the transformation ratio is 1:18, and when the input voltage is 60V, the transformation ratio is 1:6. In order to ensure that the required output voltage can be achieved at the minimum input voltage, the transformer must be designed according to the minimum input voltage of 20V to ensure that the photovoltaic module can also work in grid connection at low voltage. However, this design significantly reduces the conversion efficiency in the medium and high voltage segments, affecting the average or weighted conversion efficiency, and reducing the power generation of the photovoltaic system.

[0006] Therefore, the existing technical solutions for micro inverters have a contradiction between wide voltage range and high conversion efficiency, which is difficult to achieve at the same time.

[0007] The above problems need to be solved urgently. Summary of the invention

[0008] The present invention aims to overcome at least one of the above-mentioned disadvantages of the prior art. On the one hand, the present invention provides a maximum power control method for a photovoltaic micro-inverter, the method comprising: obtaining the output voltage and output current of a photovoltaic component; judging whether the output voltage of the photovoltaic component is greater than or equal to a preset first voltage threshold and less than a second voltage threshold; in response to the output voltage of the photovoltaic component being greater than or equal to the first voltage threshold and less than the second voltage threshold, calculating the maximum power point voltage and / or the maximum power point current corresponding to the maximum output power of the photovoltaic component based on the output voltage and output current of the photovoltaic component by running the MPPT algorithm by the controller; in response to the output voltage of the photovoltaic component being less than the first voltage threshold, causing the controller not to run the MPPT program until the output voltage of the photovoltaic component is greater than or equal to the first voltage threshold; judging whether the maximum power point voltage is greater than or equal to a preset second voltage threshold; in response to the maximum power point voltage being greater than or equal to the preset second voltage threshold, causing the controller to run the MPPT algorithm to make the photovoltaic component operate at the maximum power point voltage or the maximum power point current; in response to the maximum power point voltage being less than the preset second voltage threshold, causing the controller to run the starting point control method to make the photovoltaic component operate at the second voltage threshold or the threshold current corresponding to the second voltage threshold.

[0009] Furthermore, in response to the maximum power point voltage being greater than or equal to a preset second voltage threshold, running the MPPT algorithm through the controller to make the photovoltaic component operate at the maximum power point voltage or the maximum power point current includes: in response to the maximum power point voltage being greater than or equal to the preset second voltage threshold, performing current closed-loop control on the output current of the photovoltaic component through the controller to control the output current of the photovoltaic component to be the maximum power point current; and / or in response to the maximum power point voltage being greater than or equal to the preset second voltage threshold, performing voltage closed-loop control on the output voltage of the photovoltaic component through the controller to control the output voltage of the photovoltaic component to be the maximum power point voltage.

[0010] Furthermore, the method includes: using the maximum power point current as the set value of the control loop, using the photovoltaic module output current as the feedback value, and performing feedback control through a current loop controller to adjust the photovoltaic module output current to the maximum power point current; and / or using the maximum power point voltage as the set value of the control loop, using the photovoltaic module output voltage as the feedback value, and performing feedback control through a voltage loop controller to adjust the photovoltaic module output voltage to the maximum power point voltage.

[0011] Furthermore, in response to the maximum power point voltage being less than a preset second voltage threshold, the controller runs a starting point control method to make the photovoltaic component operate at the second voltage threshold or a current corresponding to the second voltage threshold, including: in response to the maximum power point voltage being less than the preset second voltage threshold, the controller performs current closed-loop control on the output current of the photovoltaic component to control the output current of the photovoltaic component to be a threshold current corresponding to the second voltage threshold; or in response to the maximum power point voltage being less than the preset second voltage threshold, the controller performs voltage closed-loop control on the output voltage of the photovoltaic component to control the output voltage of the photovoltaic component to be the preset second voltage threshold.

[0012] Furthermore, the method includes: using the second voltage threshold as the set value of the control loop, using the output voltage of the photovoltaic module as the feedback value, and performing feedback control through a voltage loop controller to adjust the output voltage of the photovoltaic module to the second voltage threshold; or using the threshold current corresponding to the second voltage threshold as the set value of the control loop, using the output current of the photovoltaic module as the feedback value, and performing feedback control through a current loop controller to adjust the output current of the photovoltaic module to the threshold current corresponding to the second voltage threshold.

[0013] Furthermore, the calculation formula of the threshold current corresponding to the second voltage threshold is:

[0014]

[0015] Where I2 is the threshold current corresponding to the second voltage threshold, V ocis the open circuit voltage of the photovoltaic module, V2 is the second voltage threshold, V MP is the maximum power point voltage, I MP is the maximum power point current.

[0016] Furthermore, the photovoltaic micro-inverter includes a DC boost module, a full-bridge inverter module and a control module; the input end of the DC boost module is connected to the output end of the photovoltaic component, the output end of the DC boost module is connected to the input end of the full-bridge inverter module, the output end of the full-bridge inverter module is connected to the AC power grid, and the control module is connected to the DC boost module and the full-bridge inverter module; the DC boost module adopts voltage closed-loop control and / or current closed-loop control to make the photovoltaic component work at a set working point; the full-bridge inverter module adopts voltage closed-loop control and / or current closed-loop control to keep the output voltage of the DC boost module at the desired set point, and outputs the AC current to the AC power grid in grid connection.

[0017] Furthermore, the method also includes: when the output voltage of the photovoltaic component is less than a second voltage threshold, the DC boost module is in a non-working state; when the output voltage of the photovoltaic component is greater than or equal to the second voltage threshold, the DC boost module is in a working state.

[0018] Furthermore, the method also includes: after the DC boost module is started, its output voltage gradually increases, and when the output voltage of the DC boost module is less than a third voltage threshold, the grid-connected output function is turned off; when the output voltage of the DC boost module is greater than or equal to the third voltage threshold, the grid-connected output function is started.

[0019] In a second aspect, the present invention provides a maximum power control device for a photovoltaic micro-inverter, the device comprising: an acquisition unit, adapted to acquire the output voltage and output current of a photovoltaic module; a first judgment unit, adapted to judge whether the output voltage of the photovoltaic module is greater than or equal to a preset first voltage threshold and less than a second voltage threshold; a calculation unit, adapted to calculate the maximum power point voltage and / or the maximum power point current corresponding to the maximum output power of the photovoltaic module based on the output voltage and output current of the photovoltaic module by running an MPPT algorithm through a controller in response to the output voltage of the photovoltaic module being greater than or equal to the first voltage threshold and less than the second voltage threshold; a first control unit, adapted to calculate the maximum power point voltage and / or the maximum power point current corresponding to the maximum output power of the photovoltaic module in response to the output voltage of the photovoltaic module being greater than or equal to the first voltage threshold and less than the second voltage threshold; the output voltage of the photovoltaic module is less than the first voltage threshold, so that the controller does not run the MPPT program until the output voltage of the photovoltaic module is greater than or equal to the first voltage threshold; the second judgment unit is suitable for judging whether the maximum power point voltage is greater than or equal to the preset second voltage threshold; the second control unit is suitable for, in response to the maximum power point voltage being greater than or equal to the preset second voltage threshold, running the MPPT algorithm through the controller to make the photovoltaic module operate at the maximum power point voltage or the maximum power point current; the third control unit is suitable for, in response to the maximum power point voltage being less than the preset second voltage threshold, running the starting point control method through the controller to make the photovoltaic module operate at the second voltage threshold or the threshold current corresponding to the second voltage threshold.

[0020] On the other hand, the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores one or more instructions, and the computer instructions are used to enable the computer to execute the above-mentioned maximum power control method of the photovoltaic micro-inverter.

[0021] On the other hand, the present invention provides an electronic device, comprising: a memory and a processor; the memory stores at least one program instruction; the processor implements the above-mentioned maximum power control method of the photovoltaic micro-inverter by loading and executing the at least one program instruction.

[0022] The beneficial effects of the present invention are as follows: the present invention provides a maximum power control method for a photovoltaic micro-inverter, the method comprising: obtaining an output voltage and an output current of a photovoltaic component; judging whether the output voltage of the photovoltaic component is greater than or equal to a preset first voltage threshold; in response to the output voltage of the photovoltaic component being greater than or equal to the first voltage threshold, calculating a maximum power point voltage and / or a maximum power point current corresponding to the maximum output power of the photovoltaic component based on the output voltage and the output current of the photovoltaic component by a controller running an MPPT algorithm; in response to the output voltage of the photovoltaic component being less than the first voltage threshold, causing the controller not to run an MPPT program until the output voltage of the photovoltaic component is greater than or equal to the first voltage threshold; judging whether the maximum power point voltage is greater than or equal to a preset second voltage threshold; in response to the maximum power point voltage being greater than or equal to the preset second voltage threshold, causing the controller to run an MPPT algorithm to cause the photovoltaic component to operate at a maximum power point voltage or a maximum power point current; in response to the maximum power point voltage being less than the preset second voltage threshold, causing the controller to run a starting point control method to cause the photovoltaic component to operate at a second voltage threshold or a threshold current corresponding to the second voltage threshold. In view of the problem that the prior art only uses the maximum power point voltage to determine whether to enter the working state, thereby causing waste of power generation in the low-voltage section (during the low light period), the present invention adopts a starting point control method instead of MPPT control in the low-voltage section, effectively utilizing the power generation in the low-voltage section, thereby increasing the power generation of the photovoltaic micro-inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0024] Figure 1 This is a schematic diagram of the IV curve and PV curve of a typical photovoltaic module.

[0025] Figure 2 The present invention provides a flow chart of a maximum power control method for a photovoltaic micro inverter.

[0026] Figure 3 It is a flow chart of a maximum power control method of a photovoltaic micro inverter provided by another embodiment of the present invention.

[0027] Figure 4 This is a flow chart of a maximum power control method for a photovoltaic micro-inverter provided by another embodiment of the present invention.

[0028] Figure 5 It is a schematic diagram of the structure of a micro inverter provided by an embodiment of the present invention.

[0029] Figure 6 It is a block diagram of a current closed-loop control system provided by an embodiment of the present invention.

[0030] Figure 7 It is a block diagram of a voltage closed-loop control system provided by an embodiment of the present invention.

[0031] Figure 8 It is a diagram showing the effect of the maximum power control method provided by an embodiment of the present invention.

[0032] Fig. 9 It is a schematic structural diagram of a maximum power control device for a photovoltaic micro-inverter provided in an embodiment of the present invention.

[0033] Fig.10 It is a partial block diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] It should be mentioned before discussing the exemplary embodiments in more detail that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow charts describe the operations as sequential processes, many of the operations therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but can also have additional steps not included in the accompanying drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0035] It should be understood that, although the terms "first", "second", etc. may be used herein to describe various units, these units should not be limited by these terms. These terms are used only to distinguish one unit from another unit. For example, without departing from the scope of the exemplary embodiments, the first unit may be referred to as the second unit, and similarly the second unit may be referred to as the first unit. The term "and / or" used herein includes any and all combinations of one or more of the listed associated items.

[0036] The present invention will now be described in detail with reference to the accompanying drawings. This figure is a simplified schematic diagram, which only illustrates the basic structure of the present invention in a schematic manner, and therefore only shows the components related to the present invention.

[0037] Example 1

[0038] The specific embodiments are as follows:

[0039] like Figure 2 As shown, it is a flow chart of a maximum power control method of a photovoltaic micro inverter provided by an embodiment of the present invention.

[0040] As an example, the method includes: S110: Obtain the output voltage and output current of the photovoltaic module; S120: Determine whether the output voltage of the photovoltaic module is greater than or equal to a preset first voltage threshold and less than a second voltage threshold; S130: In response to the output voltage of the photovoltaic module being greater than or equal to the first voltage threshold and less than the second voltage threshold, run the MPPT algorithm through the controller to calculate the maximum power point voltage and / or maximum power point current corresponding to the maximum output power of the photovoltaic module based on the output voltage and output current of the photovoltaic module; S140: In response to the output voltage of the photovoltaic module being less than the first voltage threshold, make the controller not run the MPPT program until the output voltage of the photovoltaic module is greater than or equal to the first voltage threshold; S150: Determine whether the maximum power point voltage is greater than or equal to a preset second voltage threshold; S160: In response to the maximum power point voltage being greater than or equal to the preset second voltage threshold, run the MPPT algorithm through the controller to make the photovoltaic module operate at the maximum power point voltage or maximum power point current; S170: In response to the maximum power point voltage being less than the preset second voltage threshold, run the starting point control method through the controller to make the photovoltaic module operate at the second voltage threshold or the threshold current corresponding to the second voltage threshold. Among them, the controller is an integral part of the photovoltaic micro-inverter, that is, the above-mentioned controller is the controller of the photovoltaic micro-inverter. Preferably, S120: Determine whether the output voltage of the photovoltaic module is greater than or equal to a preset first voltage threshold includes: The first voltage threshold V1 is the voltage value for starting MPPT control, and the value range of the first voltage threshold V1 is 12-18V.

[0041] Preferably, S130: In response to the output voltage of the photovoltaic module being greater than or equal to the first voltage threshold, run the MPPT algorithm through the controller to calculate the maximum power point voltage and / or maximum power point current corresponding to the maximum output power of the photovoltaic module based on the output voltage and output current of the photovoltaic module; and S140: In response to the output voltage of the photovoltaic module being less than the first voltage threshold, make the controller not run the MPPT program until the output voltage of the photovoltaic module is greater than or equal to the first voltage threshold includes: When the output voltage V of the photovoltaic module PV < V1, the controller is in an idle state (waiting state); when the output voltage V of the photovoltaic module PV ≥ V1, the controller starts to run the MPPT algorithm.

[0042] Preferably, S150: Determine whether the maximum power point voltage is greater than or equal to a preset second voltage threshold includes: The second voltage threshold V2 is the voltage value for starting the DC boost module, and the value range of V2 is 16-25V, where the second voltage threshold V2 is greater than the first voltage threshold V1.

[0043] Preferably, as Figure 3-4As shown, S160: When the maximum power point voltage is greater than or equal to a preset second voltage threshold, operating the MPPT algorithm through a controller to make the photovoltaic module operate at the maximum power point voltage or the maximum power point current includes: When the maximum power point voltage is greater than or equal to the preset second voltage threshold, performing current closed-loop control on the output current of the photovoltaic module through the controller to control the output current of the photovoltaic module to be the maximum power point current; and / or when the maximum power point voltage is greater than or equal to the preset second voltage threshold, performing voltage closed-loop control on the output voltage of the photovoltaic module through the controller to control the output voltage of the photovoltaic module to be the maximum power point voltage. That is, when the maximum power point voltage V MP ≥V2, current closed-loop control, voltage closed-loop control, or current-voltage double closed-loop control can be adopted to make the output current of the photovoltaic module stable at the maximum power point current I MP through closed-loop feedback regulation, or make the output voltage of the photovoltaic module stable at the maximum power point voltage V MP .

[0044] Preferably, as Figure 3-4 shown, S170: When the maximum power point voltage is less than the preset second voltage threshold, operating the starting point control method through a controller to make the photovoltaic module operate at the second voltage threshold or the threshold current corresponding to the second voltage threshold includes: When the maximum power point voltage is less than the preset second voltage threshold, performing current closed-loop control on the output current of the photovoltaic module through the controller to control the output current of the photovoltaic panel to be the threshold current corresponding to the second voltage threshold; and / or when the maximum power point voltage is less than the preset second voltage threshold, performing voltage closed-loop control on the output voltage of the photovoltaic module through the controller to control the output voltage of the photovoltaic panel to be the preset second voltage threshold. That is, when the maximum power point voltage V MP <V2, current closed-loop control, voltage closed-loop control, or current-voltage double closed-loop control can be adopted to make the output current of the photovoltaic module stable at the threshold current I2 corresponding to the second voltage threshold through closed-loop feedback regulation, or make the output voltage of the photovoltaic module stable at the second voltage threshold V2. Wherein, in the formula, I2 is the threshold current corresponding to the second voltage threshold, V oc is the open-circuit voltage of the photovoltaic module, V2 is the second voltage threshold, V MP is the maximum power point voltage, I MP is the maximum power point current.

[0045] Preferably, as Figure 6As shown, in response to the maximum power point voltage being greater than or equal to a preset second voltage threshold, the output current of the photovoltaic module is controlled by the controller in a current closed loop, and the output current of the photovoltaic panel is controlled to be the maximum power point current, including: using the maximum power point current as the setting value of the control loop; using the output current of the photovoltaic module as the feedback value; and performing feedback control by the current loop controller to adjust the output current of the photovoltaic module to the maximum power point current. Specifically, the maximum power point current I MP As the set value of the control loop, that is, I ref =I MP , with the photovoltaic module output current I PV As the feedback value, the current loop controller (such as a proportional integral controller) is used for feedback control to adjust the duty cycle of the switching device in the DC boost module to adjust the output current I PV Adjust to the MPPT setting value I MP . And / or use the maximum power point voltage as the set value of the control loop, use the photovoltaic module output voltage as the feedback value, and perform feedback control through the voltage loop controller to adjust the photovoltaic module output voltage to the maximum power point voltage.

[0046] Preferably, Figure 7 As shown, in response to the maximum power point voltage being less than the preset second voltage threshold, the controller performs voltage closed-loop control on the output voltage of the photovoltaic module, and controlling the output voltage of the photovoltaic module to be the preset second voltage threshold includes: using the second voltage threshold as the setting value of the control loop; using the output voltage of the photovoltaic module as the feedback value; performing feedback control through the voltage loop controller to adjust the output voltage of the photovoltaic module to the second voltage threshold; or using the threshold current corresponding to the second voltage threshold as the setting value of the control loop, using the output current of the photovoltaic module as the feedback value, and performing feedback control through the current loop controller to adjust the output current of the photovoltaic module to the threshold current corresponding to the second voltage threshold. Specifically, using the second voltage threshold V2 as the setting value of the control loop, that is, V ref = V2, with the photovoltaic module output voltage V PV As the feedback value, the voltage loop controller (such as a proportional integral controller) is used for feedback control to adjust the duty cycle of the switching device in the DC boost module to increase the output voltage V PV Adjust to the second voltage threshold V2. In view of the problem that the prior art only uses the maximum power point voltage to determine whether to enter the working state, thereby causing the waste of power generation in the low-voltage section (during the low-light period), the above embodiment uses the threshold voltage control method instead of MPPT control in the low-voltage section to effectively utilize the power generation in the low-voltage section, thereby increasing the power generation of the photovoltaic micro-inverter. Furthermore, since there is no need to consider the waste of power generation in the low-voltage section, a larger minimum input voltage V minThe value is convenient for optimizing the circuit design and control in the medium and high voltage segments, improving the conversion efficiency of the micro-inverter in the low, medium, and high voltage segments, and thus further increasing the power generation of the micro-inverter.

[0047] Preferably, as Figure 5 shown, the photovoltaic micro-inverter includes a DC boost module 1, a full-bridge inverter module 2, and a control module 3; the input end of the DC boost module 1 is connected to the output end of the photovoltaic module, the output end of the DC boost module 1 is connected to the input end of the full-bridge inverter module 2, the output end of the full-bridge inverter module 2 is connected to the AC grid, and the control module 3 is connected to the DC boost module 1 and the full-bridge inverter module 2; the DC boost module 1 adopts voltage closed-loop control and / or current closed-loop control to make the photovoltaic module work at a set operating point; the full-bridge inverter module 2 adopts voltage closed-loop control and / or current closed-loop control to keep the output voltage of the DC boost module 1 at a desired set point and output the AC current to the AC grid for grid connection. Further, when the output voltage of the photovoltaic module is less than the second voltage threshold V2, the DC boost module 1 is in a non-operating state; when the output voltage of the photovoltaic module is greater than or equal to the second voltage threshold V2, the DC boost module 1 is in an operating state.

[0048] Preferably, the method further includes that after the DC boost module is started, its output voltage gradually increases. When the output voltage of the DC boost module is less than the third voltage threshold, the grid connection output function is turned off; when the output voltage of the DC boost module is greater than or equal to the third voltage threshold, the grid connection output function is started.

[0049] Preferably, as Figure 8 shown, it is a schematic diagram of the simulation result of the maximum power control method of the micro-inverter adopting this embodiment. At the second voltage threshold V2 = 22V, under low light conditions, when the light intensity G < 100 (W / m 2 ), the maximum power point voltage V MP < V2. If the traditional MPPT control method is adopted, the DC boost circuit does not work and the power generation of the photovoltaic panel is wasted. By adopting the maximum power control method proposed by the present invention, voltage closed-loop control with a reference value V MP < V2 is adopted during the period of V ref = V2, and the DC boost circuit reaches the working condition, and the power generation of the photovoltaic panel can be effectively utilized. At the same time, due to the selection of a larger second voltage threshold, it is convenient to optimize the circuit design and control in the medium and high voltage segments (V PV ≥ V2), improve the conversion efficiency in the low, medium, and high voltage segments, and thus further increase the power generation of the micro-inverter.

[0050] Embodiment 2

[0051] Please refer to Fig. 9, this embodiment provides a schematic structural diagram of a maximum power control device for a photovoltaic micro-inverter.

[0052] As an example, the device comprises:

[0053] The acquisition unit 910 is adapted to acquire the output voltage and output current of the photovoltaic module.

[0054] The first judgment unit 920 is adapted to judge whether the output voltage of the photovoltaic component is greater than or equal to a preset first voltage threshold and less than a second voltage threshold.

[0055] The calculation unit 930 is adapted to calculate the maximum power point voltage and / or the maximum power point current corresponding to the maximum output power of the photovoltaic component based on the output voltage and the output current of the photovoltaic component by running the MPPT algorithm through the controller in response to the output voltage of the photovoltaic component being greater than or equal to the first voltage threshold and less than the second voltage threshold.

[0056] The first control unit 940 is adapted to, in response to the output voltage of the photovoltaic assembly being less than a first voltage threshold, cause the controller not to run the MPPT program until the output voltage of the photovoltaic assembly is greater than or equal to the first voltage threshold.

[0057] The second judging unit 950 is adapted to judge whether the maximum power point voltage is greater than or equal to a preset second voltage threshold.

[0058] The second control unit 960 is adapted to operate the MPPT algorithm through the controller to make the photovoltaic assembly operate at the maximum power point voltage or the maximum power point current in response to the maximum power point voltage being greater than or equal to a preset second voltage threshold.

[0059] The third control unit 970 is adapted to, in response to the maximum power point voltage being less than a preset second voltage threshold, execute a starting point control method through a controller to make the photovoltaic assembly operate at a second voltage threshold or a threshold current corresponding to the second voltage threshold.

[0060] It is not difficult to find that this embodiment is a device embodiment corresponding to the first embodiment, and this embodiment can be implemented in conjunction with the first embodiment. The relevant technical details mentioned in the first embodiment are still valid in this embodiment, and in order to reduce repetition, they are not repeated here. Accordingly, the relevant technical details mentioned in this embodiment can also be applied in the first embodiment.

[0061] Example 3

[0062] The embodiment of the present invention further proposes a storage medium, on which a maximum power control method for a photovoltaic micro-inverter is stored, and when the maximum power control program for the photovoltaic micro-inverter is executed by a processor, the steps of the maximum power control method for the photovoltaic micro-inverter as described above are implemented. Since the storage medium adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here one by one.

[0063] Example 4

[0064] See also Fig.10 An embodiment of the present invention also provides an electronic device, comprising: a memory and a processor; the memory stores at least one program instruction; the processor implements the maximum power control method of the photovoltaic micro-inverter provided in Example 1 by loading and executing the at least one program instruction.

[0065] The memory 602 and the processor 601 are connected in a bus manner, and the bus may include any number of interconnected buses and bridges, and the bus connects various circuits of one or more processors 601 and the memory 602 together. The bus can also connect various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be one element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices on a transmission medium. The data processed by the processor 601 is transmitted on a wireless medium via an antenna, and further, the antenna also receives data and transmits the data to the processor 601.

[0066] The processor 601 is responsible for managing the bus and general processing, and can also provide various functions, including timing, peripheral interfaces, voltage regulation, power management and other control functions. The memory 602 can be used to store data used by the processor 601 when performing operations.

[0067] The above is only an embodiment of the present invention. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field know all the common technical knowledge in the technical field of the invention before the application date or priority date, can know all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the scope of protection of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A maximum power control method for a photovoltaic micro inverter, characterized in that: The method comprises: Obtain the output voltage and output current of the photovoltaic module; Determining whether the output voltage of the photovoltaic module is greater than or equal to a preset first voltage threshold and less than a second voltage threshold; In response to the output voltage of the photovoltaic assembly being greater than or equal to a first voltage threshold and less than a second voltage threshold, a controller runs an MPPT algorithm to calculate a maximum power point voltage and / or a maximum power point current corresponding to the maximum output power of the photovoltaic assembly based on the output voltage and output current of the photovoltaic assembly; In response to the output voltage of the photovoltaic assembly being less than a first voltage threshold, causing the controller not to run the MPPT program until the output voltage of the photovoltaic assembly is greater than or equal to the first voltage threshold; Determining whether the maximum power point voltage is greater than or equal to a preset second voltage threshold; In response to the maximum power point voltage being greater than or equal to a preset second voltage threshold, the controller causes the photovoltaic assembly to operate at the maximum power point voltage or the maximum power point current according to the calculation result of the MPPT algorithm; In response to the maximum power point voltage being less than a preset second voltage threshold, the controller runs a start point control method to make the photovoltaic assembly operate at the second voltage threshold or a threshold current corresponding to the second voltage threshold.

2. The maximum power control method of a photovoltaic micro-inverter according to claim 1, characterized in that: In response to the maximum power point voltage being greater than or equal to a preset second voltage threshold, the controller causes the photovoltaic assembly to operate at the maximum power point voltage or the maximum power point current according to the calculation result of the MPPT algorithm, including: In response to the maximum power point voltage being greater than or equal to a preset second voltage threshold, a controller is used to perform current closed-loop control on an output current of the photovoltaic assembly to control the output current of the photovoltaic assembly to be a maximum power point current; and / or In response to the maximum power point voltage being greater than or equal to a preset second voltage threshold, a controller performs voltage closed-loop control on the output voltage of the photovoltaic assembly to control the output voltage of the photovoltaic assembly to be the maximum power point voltage.

3. The maximum power control method of a photovoltaic micro-inverter according to claim 2, characterized in that: The method comprises: Using the maximum power point current as the set value of the control loop and the PV module output current as the feedback value, the PV module output current is adjusted to the maximum power point current by feedback control through the current loop controller; and / or The maximum power point voltage is used as the set value of the control loop, and the output voltage of the photovoltaic module is used as the feedback value. Feedback control is performed through the voltage loop controller to adjust the output voltage of the photovoltaic module to the maximum power point voltage.

4. The maximum power control method of a photovoltaic micro-inverter according to claim 1, characterized in that: In response to the maximum power point voltage being less than a preset second voltage threshold, the controller runs a starting point control method to make the photovoltaic assembly operate at the second voltage threshold or a current corresponding to the second voltage threshold, including: In response to the maximum power point voltage being less than a preset second voltage threshold, a controller is used to perform current closed-loop control on an output current of the photovoltaic assembly to control the output current of the photovoltaic assembly to be a threshold current corresponding to the second voltage threshold; or In response to the maximum power point voltage being less than a preset second voltage threshold, a controller performs voltage closed-loop control on the output voltage of the photovoltaic assembly to control the output voltage of the photovoltaic assembly to be the preset second voltage threshold.

5. The maximum power control method of a photovoltaic micro-inverter according to claim 4, characterized in that: The method comprises: Using the second voltage threshold as the set value of the control loop and the output voltage of the photovoltaic module as the feedback value, the voltage loop controller is used for feedback control to adjust the output voltage of the photovoltaic module to the second voltage threshold; or The threshold current corresponding to the second voltage threshold is used as the set value of the control loop, and the photovoltaic component output current is used as the feedback value. Feedback control is performed through the current loop controller to adjust the photovoltaic component output current to the threshold current corresponding to the second voltage threshold.

6. The maximum power control method of a photovoltaic micro-inverter according to claim 4, characterized in that: The calculation formula of the threshold current corresponding to the second voltage threshold is: Where I2 is the threshold current corresponding to the second voltage threshold, V oc is the open circuit voltage of the photovoltaic module, V2 is the second voltage threshold, V MP is the maximum power point voltage, I MP is the maximum power point current.

7. The maximum power control method of a photovoltaic micro-inverter according to claim 1, characterized in that: The photovoltaic micro inverter includes a DC boost module, a full-bridge inverter module and a control module; The input end of the DC boost module is connected to the output end of the photovoltaic module, the output end of the DC boost module is connected to the input end of the full-bridge inverter module, the output end of the full-bridge inverter module is connected to the AC power grid, and the control module is connected to the DC boost module and the full-bridge inverter module; The DC boost module adopts voltage closed-loop control and / or current closed-loop control to make the photovoltaic module work at a set working point; The full-bridge inverter module adopts voltage closed-loop control and / or current closed-loop control to maintain the output voltage of the DC boost module at a desired set point and output the AC current to the AC grid in grid connection.

8. The maximum power control method of a photovoltaic micro-inverter according to claim 7, characterized in that: The method further comprises: When the output voltage of the photovoltaic module is less than the second voltage threshold, the DC boost module is in a non-working state; When the output voltage of the photovoltaic module is greater than or equal to the second voltage threshold, the DC boost module is in working state.

9. The maximum power control method of a photovoltaic micro-inverter according to claim 8, characterized in that: The method further comprises: After the DC boost module is started, its output voltage gradually increases. When the output voltage of the DC boost module is less than the third voltage threshold, the grid-connected output function is turned off. When the output voltage of the DC boost module is greater than or equal to the third voltage threshold, the grid-connected output function is started.

10. A maximum power control device for a photovoltaic micro inverter, characterized in that: The device comprises: An acquisition unit, adapted to acquire an output voltage and an output current of a photovoltaic module; A first judgment unit, adapted to judge whether the output voltage of the photovoltaic assembly is greater than or equal to a preset first voltage threshold and less than a second voltage threshold; a calculation unit, adapted to, in response to an output voltage of the photovoltaic assembly being greater than or equal to a first voltage threshold and less than a second voltage threshold, calculate a maximum power point voltage and / or a maximum power point current corresponding to a maximum output power of the photovoltaic assembly based on the output voltage and output current of the photovoltaic assembly by running an MPPT algorithm through a controller; a first control unit adapted to, in response to the output voltage of the photovoltaic assembly being less than a first voltage threshold, cause the controller not to run the MPPT program until the output voltage of the photovoltaic assembly is greater than or equal to the first voltage threshold; A second judgment unit, adapted to judge whether the maximum power point voltage is greater than or equal to a preset second voltage threshold; A second control unit is adapted to operate the MPPT algorithm through a controller to make the photovoltaic assembly operate at a maximum power point voltage or a maximum power point current in response to the maximum power point voltage being greater than or equal to a preset second voltage threshold; The third control unit is adapted to, in response to the maximum power point voltage being less than a preset second voltage threshold, execute a starting point control method through a controller to make the photovoltaic assembly operate at a second voltage threshold or a threshold current corresponding to the second voltage threshold.

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