MPPT confluence circuit and method and photovoltaic inverter
By designing an MPPT bus circuit, the energy of multiple photovoltaic power generation components is flooded to at least one MPPT circuit, which solves the problem that the photovoltaic inverter cannot be connected to the grid under low light conditions and the MPPT circuit is large, achieving longer grid connection time and higher power generation efficiency.
Patent Information
- Application Number
- CN202510386642.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-28
- Publication Date
- 2025-06-10
AI Technical Summary
When the sun's illumination intensity is weak, the photovoltaic inverter cannot drive the maximum power point tracking (MPPT) circuit, resulting in a shortened network connection time throughout the day. The MPPT circuit is high in losses when working in small current scenarios, and the economy is poor.
An MPPT bus circuit is designed, including an N-channel maximum power point tracking MPPT circuit and an N-1 bus switch group. By controlling the on or off of the bus switch group through a control signal, the energy of multiple photovoltaic power generation components is flooded to at least one MPPT circuit.
The photovoltaic inverter is extended for the whole day grid connection time, avoiding the loss of the MPPT circuit working in small current scenarios, and improving the power generation efficiency and economicality under low-light conditions.
Smart Images
Figure CN120127754A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of photovoltaic power generation, and particularly to an MPPT converging circuit, a method and a photovoltaic inverter. Background Art
[0002] A photovoltaic inverter is a core component of a photovoltaic power generation system and is used to convert direct current generated by photovoltaic modules into alternating current. However, in a photovoltaic inverter, only when the photovoltaic power generation module reaches a certain power capacity can it drive a maximum power point tracking (MPPT) circuit to connect the photovoltaic inverter to the grid. Therefore, when the solar illumination intensity is weak, the power of the photovoltaic power generation module is low and cannot drive the MPPT circuit, resulting in a shortened grid connection time throughout the day. Moreover, even if the MPPT circuit starts successfully when the solar illumination intensity is weak, each MPPT circuit operates in a small current scenario, resulting in relatively high losses and poor economy. Summary of the Invention
[0003] An embodiment of the present invention provides an MPPT converging circuit for extending the grid connection time of a photovoltaic inverter throughout the day when the solar illumination intensity is weak, and at the same time avoiding the operation of the MPPT circuit in a small current scenario and reducing losses. The MPPT converging circuit includes N maximum power point tracking (MPPT) circuits and N - 1 converging switch groups, where N is an integer greater than or equal to 2. The input end of each MPPT circuit is connected to a photovoltaic power generation module, and the output ends of each MPPT circuit are connected in parallel to a DC bus. Wherein, the N - 1 converging switch groups are respectively connected to N - 1 MPPT circuits, and each converging switch group includes a first switch tube and a second switch tube. The first end of the first switch tube of each converging switch group is connected to the first end of the second switch tube. The second end of the first switch tube is connected to the input end of the MPPT circuit connected to the converging switch group, and the second end of the second switch tube is connected to the input end of the next MPPT circuit arranged in sequence. Wherein, the polarities of the first end of the first switch tube and the first end of the second switch tube are the same, and the polarities of the second end of the first switch tube and the second end of the second switch tube are the same. The energy of multiple photovoltaic power generation modules is converged to at least one MPPT circuit by controlling the conduction or cut-off of the first switch tube and the second switch tube of each converging switch group through a control signal.
[0004] In one embodiment, the MPPT converging circuit further includes N - 1 interlock driving circuits, and each interlock driving circuit is connected to a converging switch group for controlling the conduction or cut-off of the first switch tube and the second switch tube of each converging switch group according to a control signal. Among them, the first switch tube and the second switch tube of each busbar switch group are not turned on simultaneously.
[0005] In one embodiment, each of the interlock drive circuits includes a first optocoupler, a second optocoupler, a first logic gate module, and a second logic gate module; Among them, the first logic gate module includes a first AND gate, a first NOT gate, and a first buffer gate, and the second logic gate module includes a second AND gate, a second NOT gate, and a second buffer gate; the input end of the first buffer gate is connected to the input end of the second NOT gate for receiving a first control signal; the input end of the first NOT gate is connected to the input end of the second buffer gate for receiving a second control signal; the output end of the first buffer gate and the output end of the first NOT gate are respectively connected to the two input ends of the first AND gate, the output end of the second buffer gate and the output end of the second NOT gate are respectively connected to the two input ends of the second AND gate, the output end of the first AND gate is connected to the third end of the first switch tube through the first optocoupler, the output end of the second AND gate is connected to the third end of the second switch tube through the second optocoupler, and the polarities of the third ends of the first switch tube and the second switch tube are the same.
[0006] In one embodiment, each MPPT circuit detects the output current of the photovoltaic power generation module connected to this MPPT circuit, determines whether this MPPT circuit operates independently according to the output current of the photovoltaic power generation module connected to this MPPT circuit, and issues a control signal to control the conduction or cut-off of the first switch tube and the second switch tube of the busbar switch group connected to this MPPT circuit.
[0007] In one embodiment, the MPPT busbar circuit further includes a control unit, and the control unit is used to obtain the output current of the photovoltaic power generation module connected to each MPPT circuit, determine whether each MPPT circuit operates independently according to the output current of the photovoltaic power generation module connected to each MPPT circuit, and issue a control signal to control the conduction or cut-off of the first switch tube and the second switch tube of the busbar switch group connected to each MPPT circuit.
[0008] The embodiment of the present invention further provides an MPPT busbar method, and this MPPT busbar method is applied to the above MPPT busbar circuit to extend the all-day grid connection time of the photovoltaic inverter when the solar light intensity is weak, and at the same time avoid the MPPT circuit from working in a small current scenario to reduce losses; this MPPT busbar method includes: Determine whether each MPPT circuit operates independently according to the output current of the photovoltaic power generation module connected to each MPPT circuit, and issue a control signal; Control the conduction or cutoff of the first switch tube and the second switch tube of the busbar switch group connected to each MPPT circuit according to the control signal, so as to converge the energy of multiple photovoltaic power generation components to at least one MPPT circuit.
[0009] In one embodiment, judging whether each MPPT circuit operates independently according to the output current of the photovoltaic power generation components connected to each MPPT circuit includes: Compare the output current of the photovoltaic power generation components connected to each MPPT circuit with a preset MPPT busbar current range. When the output current of the photovoltaic power generation components connected to any MPPT circuit is within the MPPT busbar current range, then this MPPT circuit operates independently; When the output current of the photovoltaic power generation components connected to any MPPT circuit is less than the minimum boundary threshold of the MPPT busbar current range, then this MPPT circuit does not operate independently; If the output current of the photovoltaic power generation components connected to any MPPT circuit is greater than the maximum boundary threshold of the MPPT busbar current range, then compare the output current of the photovoltaic power generation components connected to other MPPT circuits with the maximum boundary threshold. When the output current of the photovoltaic power generation components connected to other MPPT circuits is greater than or equal to the maximum boundary threshold, then this MPPT circuit operates independently; when the output current of the photovoltaic power generation components connected to other MPPT circuits is less than the maximum boundary threshold, then this MPPT circuit operates independently, and the output current of the photovoltaic power generation components connected to this MPPT circuit is shunted to other MPPT circuits for busbar connection.
[0010] In one embodiment, the MPPT busbar current range is set according to the efficiency curve of the MPPT circuit.
[0011] An embodiment of the present invention further provides a photovoltaic inverter, which includes an inverter circuit and the above-mentioned MPPT busbar connection circuit; Wherein, the input side of the MPPT busbar connection circuit is connected to multiple photovoltaic power generation components, and the output side of the MPPT busbar connection circuit is connected to the inverter circuit through a DC busbar; the MPPT busbar connection circuit is used to converge the energy of multiple photovoltaic power generation components to at least one MPPT circuit and input it into the inverter circuit.
[0012] An embodiment of the present invention further provides a photovoltaic power generation system, which includes the above-mentioned photovoltaic inverter.
[0013] The MPPT busbar circuit provided by the embodiment of the present invention includes N maximum power point tracking (MPPT) circuits and N - 1 busbar switch groups, where N is an integer greater than or equal to 2; the input end of each MPPT circuit is connected to a photovoltaic power generation module, and the output ends of each MPPT circuit are connected in parallel to the DC busbar; among them, the N - 1 busbar switch groups are respectively connected to N - 1 MPPT circuits, and each busbar switch group includes a first switch tube and a second switch tube; the first end of the first switch tube of each busbar switch group is connected to the first end of the second switch tube, the second end of the first switch tube is connected to the input end of the MPPT circuit connected to this busbar switch group, and the second end of the second switch tube is connected to the input end of the next MPPT circuit arranged in sequence; among them, the polarities of the first end of the first switch tube and the first end of the second switch tube are the same, and the polarities of the second end of the first switch tube and the second end of the second switch tube are the same; the energy of multiple photovoltaic power generation modules is busbar-connected to at least one MPPT circuit by controlling the conduction or cut-off of the first switch tube and the second switch tube of each busbar switch group through a control signal. In this way, in a low-light scenario, the MPPT busbar circuit can busbar-connect multiple photovoltaic power generation modules to one MPPT circuit or several MPPT circuits, extend the all-day grid connection time of the photovoltaic inverter, and at the same time avoid the MPPT circuit from operating in a small-current scenario, reduce the number of starting MPPT circuits in a low-light scenario, thereby reducing losses and maximizing the utilization of the energy of the photovoltaic power generation module. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0015] In the drawings: Figure 1 is a schematic diagram of a two-stage photovoltaic inverter in an embodiment of the present invention; Figure 2 is a schematic diagram of a three-stage photovoltaic inverter in an embodiment of the present invention; Figure 3 、 Figure 4 and Figure 5 are schematic diagrams of the current busbar connection directions of the three-stage photovoltaic inverter in the embodiment of the present invention Figure 2 ; Figure 6 is a schematic diagram of an interlock drive circuit in an embodiment of the present invention; Figure 7 is a schematic diagram of the efficiency curve of an MPPT circuit in an embodiment of the present invention; Figure 8 This is a logic diagram for MPPT circuit bus connection judgment in an embodiment of the present invention; Figure 9 This is a flowchart of an MPPT bus connection method in an embodiment of the present invention. Detailed implementation manners
[0016] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer and more understandable, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Herein, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but do not limit the present invention.
[0017] In the description of this specification, the terms "comprising", "including", "having", "containing", etc. are all open-ended terms, that is, they are meant to include but not be limited to. The descriptions with reference to terms such as "one embodiment", "one specific embodiment", "some embodiments", "for example", etc. mean that the specific features, structures or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. The order of steps involved in each embodiment is used to schematically illustrate the implementation of the present application, and the order of steps is not limited and can be adjusted appropriately as needed.
[0018] Through research, it is found that when the solar irradiance is weak, the power of the photovoltaic power generation module is low and cannot drive the MPPT circuit, resulting in a shortened grid connection time throughout the day and low power generation efficiency. Moreover, even if the MPPT circuit starts successfully when the solar irradiance is weak and each MPPT circuit operates in a small current scenario, it will also result in relatively high losses and does not have good economy. Currently, a component power detection circuit and a voltage threshold method are used as the conditions for judging whether the MPPT circuit reaches the start-up condition, but this method does not have a front-end bus connection function and cannot effectively solve problems such as shortened grid connection time throughout the day and low power generation efficiency.
[0019] Based on this, the embodiments of the present invention provide an MPPT bus connection solution for a photovoltaic inverter. When the solar irradiance is weak, it can realize the bus connection of multiple photovoltaic power generation modules to one or several MPPTs, enabling the photovoltaic inverter to start earlier in the morning and stop later at night, making more full use of solar irradiance. At the same time, in a low-light scenario, the number of started MPPT circuits is reduced, thereby generating less loss and maximizing the utilization of the energy of the photovoltaic power generation module.
[0020] An embodiment of the present invention provides an MPPT busbar circuit. The MPPT busbar circuit can be arranged in a multi-stage photovoltaic inverter. The input side of the MPPT busbar circuit is connected to multiple photovoltaic power generation components, and the output side is connected to an inverter circuit through a DC busbar. Through the MPPT busbar circuit, the energy of multiple photovoltaic power generation components can be busbar-connected to at least one MPPT circuit and input into the inverter circuit, realizing multi-path busbar connection of the photovoltaic inverter.
[0021] The above MPPT busbar circuit may include N MPPT circuits and N - 1 busbar switch groups, where N is an integer greater than or equal to 2; the input end of each MPPT circuit is connected to a photovoltaic power generation component, and the output ends of each MPPT circuit are connected in parallel to the DC busbar.
[0022] Among them, N - 1 busbar switch groups are respectively connected to N - 1 MPPT circuits. Each busbar switch group includes a first switch tube and a second switch tube; the first ends of the first switch tube and the second switch tube in each busbar switch group are connected, the second end of the first switch tube is connected to the input end of the MPPT circuit connected to this busbar switch group, and the second end of the second switch tube is connected to the input end of the next MPPT circuit arranged in sequence; among them, the polarities of the first ends of the first switch tube and the second switch tube are the same, and the polarities of the second ends of the first switch tube and the second switch tube are the same.
[0023] By controlling signals to control the conduction or cut-off of the first switch tube and the second switch tube in each busbar switch group, the energy of multiple photovoltaic power generation components is busbar-connected to at least one MPPT circuit.
[0024] In specific implementation, in each busbar switch group, the connection mode of the two switch tubes is reverse-connected. For example, the common sources of the two switch tubes are reverse-connected (the first ends are the sources), or the common drains are reverse-connected (the first ends are the drains), so as to make the current direction controllable when the two switch tubes are respectively closed. In the case of reverse-connecting the common sources, the sources of the first switch tube and the second switch tube are connected, the drain of the first switch tube is connected to the input end of the MPPT circuit connected to this busbar switch group, and the drain of the second switch tube is connected to the input end of the next MPPT circuit arranged in sequence; or, in the case of reverse-connecting the common drains, the drains of the first switch tube and the second switch tube are connected, the source of the first switch tube is connected to the input end of the MPPT circuit connected to this busbar switch group, and the source of the second switch tube S12 is connected to the input end of the next MPPT circuit arranged in sequence.
[0025] It should be noted that the above first switch tube and second switch tube can be MOS tubes or other types of switch tubes, and there is no limitation here.
[0026] In a specific example, Figure 1Schematic diagram of a two - stage photovoltaic inverter provided by an embodiment of the present invention. As Figure 1 shown, in the two - stage photovoltaic inverter, the MPPT current - collecting circuit includes two MPPT circuits (MPPT A and MPPT B) and one current - collecting switch group, and this current - collecting switch group is connected to MPPT A. Specifically, this current - collecting switch group includes a first switch tube S11 and a second switch tube S12; the source (first end) of the first switch tube S11 is connected to the source (first end) of the second switch tube S12, the drain (second end) of the first switch tube S11 is connected to the positive pole of the input end of MPPT A, and the drain (second end) of the second switch tube S12 is connected to the positive pole of the input end of MPPT B.
[0027] Figure 1 In Figure 1 , when the first switch tube S11 is turned on and the second switch tube S12 is turned off, the current direction is from the first switch tube S11 to the second switch tube S12, and the current can be collected to MPPT B; when the second switch tube S12 is turned on and the first switch tube S11 is turned off, the current direction is from the second switch tube S12 to the first switch tube S11, and the current can be collected to MPPT A.
[0028] In a specific example, Figure 2 Schematic diagram of a three - stage photovoltaic inverter provided by an embodiment of the present invention. As Figure 2 shown, in the three - stage photovoltaic inverter, the MPPT current - collecting circuit includes three MPPT circuits (MPPT A, MPPT B, and MPPT C) and two current - collecting switch groups; one of the current - collecting switch groups includes a first switch tube S11 and a second switch tube S12, and this current - collecting switch group is connected to MPPT A, and the other current - collecting switch group includes a first switch tube S21 and a second switch tube S22, and this current - collecting switch group is connected to MPPT B. Specifically, the source (first end) of the first switch tube S11 is connected to the source (first end) of the second switch tube S12, the source (first end) of the first switch tube S21 is connected to the source (first end) of the second switch tube S22, the drain (second end) of the first switch tube S11 is connected to the positive pole of the input end of the MPPT A circuit, the drain (second end) of the second switch tube S12 is connected to the positive pole of the input end of the MPPT B circuit; the drain (second end) of the first switch tube S21 is connected to the positive pole of the input end of the MPPT B circuit, and the drain (second end) of the second switch tube S22 is connected to the positive pole of the input end of the MPPT C circuit.
[0029] Figure 3 、 Figure 4 and Figure 5 are Figure 2 schematic diagrams of the current - collecting direction of the three - stage photovoltaic inverter in Figure 2 .
[0030] As Figure 3As shown, if the first switching transistor S11 is turned off and the second switching transistor S12 is turned on, the first switching transistor S21 is turned off and the second switching transistor S22 is turned on, the current can be converged to MPPT A.
[0031] As Figure 4 shown, if the first switching transistor S11 is turned on, the second switching transistor S12 is turned off, the first switching transistor S21 is turned on, and the second switching transistor S22 is turned off, the current can be converged to MPPT C.
[0032] As Figure 5 shown, if the first switching transistor S11 is turned on, the second switching transistor S12 is turned off, the first switching transistor S21 is turned off, and the second switching transistor S22 is turned on, the current can be converged to MPPT B.
[0033] Based on the above MPPT converging circuit, by controlling the conduction or turning off of the first and second switching transistors of each converging switch group, the energy of multiple photovoltaic power generation components can be converged to at least one MPPT circuit.
[0034] An interlock drive circuit is further provided in an embodiment of the present invention, which is used to drive the conduction or turning off of the first and second switching transistors. In one embodiment, the above MPPT converging circuit may further include N - 1 interlock drive circuits, and each interlock drive circuit is connected to a converging switch group, and is used to control the conduction or turning off of the first and second switching transistors of each converging switch group according to a control signal; wherein, the first and second switching transistors of each converging switch group are not turned on simultaneously.
[0035] Figure 6 is a schematic diagram of the interlock drive circuit provided in an embodiment of the present invention. As Figure 6 shown, the above interlock drive circuit may include a first optocoupler OC1, a second optocoupler OC2, a first logic gate module 1, and a second logic gate module 2; Among them, the first logic gate module 1 may include a first AND gate Y1, a first NOT gate F1, and a first buffer gate M1, and the second logic gate module 2 may include a second AND gate Y2, a second NOT gate F2, and a second buffer gate M2; the input end of the first buffer gate M1 is connected to the input end of the second NOT gate F2 to serve as a first signal receiving end DI / DO1 for receiving a first control signal; the input end of the first NOT gate F1 is connected to the input end of the second buffer gate M2 to serve as a second signal receiving end DI / DO2 for receiving a second control signal; the output end of the first buffer gate M1 and the output end of the first NOT gate F1 are respectively connected to the two input ends of the first AND gate Y1, and the output end of the second buffer gate M2 and the output end of the second NOT gate F2 are respectively connected to the two input ends of the second AND gate Y2. The output end of the first AND gate Y1 is connected to the third end G1 of the first switch tube S11 through a first optocoupler OC1, and the output end of the second AND gate Y2 is connected to the third end G2 of the second switch tube S12 through a second optocoupler OC2. The polarities of the third end G1 of the first switch tube S11 and the third end G2 of the second switch tube S12 are the same.
[0036] In specific implementation, the third end G1 of the first switch tube S11 and the third end G2 of the second switch tube S12 may be gates for receiving control signals output by an interlock drive circuit. Since the first switch tube and the second switch tube in each bus switch group cannot be turned on simultaneously, the interlock drive circuit is designed not to drive the first switch tube and the second switch tube in a bus switch group simultaneously. The on or off of the first switch tube and the second switch tube in each bus switch group can be controlled by the drive truth table shown in Table 1: Table 1 Drive Truth Table As shown in Table 1, for example, when the first control signal received by the first signal receiving terminal DI / DO1 is 1 and the second control signal received by the second signal receiving terminal DI / DO2 is 0, the control signal output from the first logic gate module 1 to the first switching transistor S11 is 1, and the control signal output from the second logic gate module 2 to the second switching transistor S12 is 0. At this time, the first switching transistor S11 is turned on and the second switching transistor S12 is turned off; when the first control signal is 0 and the second control signal is 1, the control signal output to the first switching transistor S11 is 0, and the control signal output to the second switching transistor S12 is 1. At this time, the first switching transistor S11 is turned off and the second switching transistor S12 is turned on; when the first control signal is 0 and the second control signal is 0, the control signals output to the first switching transistor S11 and the second switching transistor S12 are both 0. At this time, both the first switching transistor S11 and the second switching transistor S12 are turned off; when the first control signal is 1 and the second control signal is 1, the control signals output to the first switching transistor S11 and the second switching transistor S12 are both 0. At this time, both the first switching transistor S11 and the second switching transistor S12 are turned off. S11 and S12 in Table 1 are only examples, and actually applicable are the first switching transistor and the second switching transistor of each bus switch group.
[0037] Combined with Table 1 and Figure 3 it can be seen that Figure 3 the control signals are as shown in Table 2: Table 2 Control Signal One Therefore, Figure 3 in, S11 is turned off, S12 is turned on, S21 is turned off, S22 is turned on, and the current can be converged to MPPT A.
[0038] Combined with Table 1 and Figure 4 it can be seen that Figure 4 the control signals are as shown in Table 3: Table 3 Control Signal Two Therefore, Figure 4 in, S11 is turned on, S12 is turned off, S21 is turned on, S22 is turned off, and the current can be converged to MPPT C.
[0039] Combined with Table 1 and Figure 5 it can be seen that Figure 5 the control signals are as shown in Table 4: Table 4 Control Signal Three Therefore, Figure 5 in, S11 is turned on, S12 is turned off, S21 is turned off, S22 is turned on, and the current can be converged to MPPT B.
[0040] In this way, the interlock drive circuit can quickly and accurately control the first switch tube and the second switch tube in each bus switch group from conducting simultaneously through simple control logic, thereby achieving the control of the current direction.
[0041] In the embodiment of the present invention, since the intensity of sunlight mainly affects the current capacity of the photovoltaic power generation module and has relatively little influence on the voltage, it is possible to determine whether the MPPT circuit of this path needs to be converged based on the output current of the photovoltaic power generation module, and then generate a control signal.
[0042] In one embodiment, each MPPT circuit can detect the output current of the photovoltaic power generation module connected to this MPPT circuit, determine whether this MPPT circuit operates independently based on the output current of the photovoltaic power generation module connected to this MPPT circuit, and issue a control signal to control the conduction or cutoff of the first switch tube and the second switch tube of the bus switch group connected to this MPPT circuit.
[0043] During specific implementation, to determine whether the MPPT circuit needs to be converged, the output current of each MPPT circuit needs to be judged individually. Therefore, the current detection function of the MPPT circuit can be used to detect the output current of the photovoltaic power generation module, and the output current of the photovoltaic power generation module is compared with the preset MPPT convergence current range to determine whether this MPPT circuit needs to be converged.
[0044] Among them, the above MPPT convergence current range can be set according to the efficiency curve of the MPPT circuit. As Figure 7 shown, it is a schematic diagram of the efficiency curve of the MPPT circuit provided by the embodiment of the present invention. Figure 7 In [the figure], if the MPPT efficiency of 98% is set as the convergence switching point, correspondingly, when the output current of the photovoltaic power generation module is between I1 and I2, it is the high-efficiency interval. I1 is the minimum boundary threshold for the convergence of the MPPT convergence circuit, and I2 is the maximum boundary threshold for the convergence of this MPPT convergence circuit. Therefore, the MPPT convergence current range can be set as I1≤I≤I2, where I is the output current of the photovoltaic power generation module.
[0045] Based on this, Figure 8 it is a logic diagram for the convergence judgment of the MPPT circuit provided by the embodiment of the present invention. As Figure 8As shown, when performing the single-channel MPPT circuit current aggregation judgment, if the output current I of the photovoltaic power generation module connected to this channel of the MPPT circuit is within the MPPT current aggregation range, that is, I1 ≤ I ≤ I2, then this channel of the MPPT circuit operates independently. If I < I1, then this channel of the MPPT circuit does not operate independently and needs to be aggregated to other MPPT circuits. If I > I2, then the MPPT circuit cannot maintain efficient operation. Therefore, to avoid losses, the output current I of the photovoltaic power generation modules connected to other channels of the MPPT circuit is compared with I2. When the output current of the photovoltaic power generation modules connected to other channels of the MPPT circuit is less than I2, then this channel of the MPPT circuit operates independently, and the output current of the photovoltaic power generation module connected to this channel of the MPPT circuit can be shunted to other channels of the MPPT circuit for current aggregation through methods such as a power distribution algorithm, that is, the excess current I - I2 is aggregated to other MPPT circuits that can operate independently. In this way, it can be ensured that each MPPT circuit can work efficiently and reduce losses; if the output current of the photovoltaic power generation modules connected to other channels of the MPPT circuit is greater than or equal to I2, then this channel of the MPPT circuit operates independently.
[0046] During specific implementation, after determining whether each channel of the MPPT circuit needs current aggregation, corresponding control signals, that is, the first control signal and the second control signal, can be generated and sent to the interlock drive circuit. The interlock drive circuit drives the first switch tube and the second switch tube of each current aggregation switch group to conduct or turn off according to the first control signal and the second control signal, thereby realizing the current aggregation of the energy of multiple photovoltaic power generation modules to at least one channel of the MPPT circuit.
[0047] In one embodiment, to improve the control efficiency and accuracy, the MPPT current aggregation circuit can also be provided with a control unit. The control unit is used to obtain the output current of the photovoltaic power generation modules connected to each channel of the MPPT circuit, judge whether this channel of the MPPT circuit operates independently according to the output current of the photovoltaic power generation modules connected to each channel of the MPPT circuit, and issue a control signal to control the conduction or turn off of the first switch tube and the second switch tube of the current aggregation switch group connected to each channel of the MPPT circuit.
[0048] During specific implementation, as a general control module, the control unit can integrate all information to perform the MPPT circuit current aggregation judgment, further ensuring the accuracy and efficiency of the current aggregation result judgment. Among them, the control unit can judge whether each channel of the MPPT circuit needs current aggregation according to the logic diagram of the MPPT circuit current aggregation judgment as shown in Figure 8 , and no redundant elaboration will be made here.
[0049] In summary, the MPPT busbar circuit provided by the embodiments of the present invention can converge multiple photovoltaic power generation components into one or several MPPT circuits in low-light scenarios, enabling the photovoltaic inverter to start up earlier and shut down later at night, extending the power generation duration of the photovoltaic power generation components. At the same time, it avoids the MPPT circuit from operating in a low-current scenario, reduces the number of startup paths of the MPPT circuit in low-light scenarios, thereby reducing losses and maximizing the utilization of the energy of the photovoltaic power generation components.
[0050] An MPPT busbar method is also provided in the embodiments of the present invention, as described in the following embodiments. Since the principle of solving problems by this MPPT busbar method is similar to that of the above MPPT busbar circuit, the implementation of this MPPT busbar method can refer to the implementation of the MPPT busbar circuit, and the repeated parts will not be elaborated.
[0051] As Figure 9 shown, it is a flowchart of an MPPT busbar method provided by the embodiments of the present invention. This MPPT busbar method is applied to the above MPPT busbar circuit, and the method may include: Step 901, determine whether each MPPT circuit operates independently according to the output current of the photovoltaic power generation components connected to each MPPT circuit, and send a control signal. Step 902, control the conduction or cut-off of the first switch tube and the second switch tube of the busbar switch group connected to each MPPT circuit according to the control signal, so as to converge the energy of multiple photovoltaic power generation components into at least one MPPT circuit.
[0052] In one embodiment, the above step 901 may specifically include: Compare the output current of the photovoltaic power generation components connected to each MPPT circuit with a preset MPPT busbar current range. When the output current of the photovoltaic power generation components connected to any MPPT circuit is within the MPPT busbar current range, then this MPPT circuit operates independently. When the output current of the photovoltaic power generation components connected to any MPPT circuit is less than the minimum boundary threshold of the MPPT busbar current range, then this MPPT circuit does not operate independently. If the output current of the photovoltaic power generation components connected to any MPPT circuit is greater than the maximum boundary threshold of the MPPT bus current range, then compare the output currents of the photovoltaic power generation components connected to the other MPPT circuits with the maximum boundary threshold. In the case where the output currents of the photovoltaic power generation components connected to the other MPPT circuits are greater than or equal to the maximum boundary threshold, then this MPPT circuit operates independently; in the case where the output currents of the photovoltaic power generation components connected to the other MPPT circuits are less than the maximum boundary threshold, then this MPPT circuit operates independently, and the output current of the photovoltaic power generation components connected to this MPPT circuit is shunted to the bus of the other MPPT circuits.
[0053] In one embodiment, the above MPPT bus current range can be set according to the efficiency curve of the MPPT circuit.
[0054] An embodiment of the present invention further provides a photovoltaic inverter, which may include an inverter circuit and the above MPPT bus circuit; wherein, the input side of the MPPT bus circuit is connected to multiple photovoltaic power generation components, and the output side of the MPPT bus circuit is connected to the inverter circuit through a DC bus; the MPPT bus circuit is used to bus the energy of multiple photovoltaic power generation components to at least one MPPT circuit and input it into the inverter circuit. The principle of solving problems of this photovoltaic inverter is similar to that of the above MPPT bus circuit. Therefore, the implementation of this photovoltaic inverter can refer to the implementation of the MPPT bus circuit, and the repeated parts will not be described again.
[0055] An embodiment of the present invention further provides a photovoltaic power generation system, which may include the above photovoltaic inverter. The principle of solving problems of this photovoltaic power generation system is similar to that of the above MPPT bus circuit. Therefore, the implementation of this photovoltaic power generation system can refer to the implementation of the MPPT bus circuit, and the repeated parts will not be described again.
[0056] An embodiment of the present invention further provides a computer device, the computer device includes a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the computer program, the above MPPT bus method is implemented.
[0057] An embodiment of the present invention further provides a computer-readable storage medium, the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above MPPT bus method is implemented.
[0058] An embodiment of the present invention further provides a computer program product, the computer program product includes a computer program, and when the computer conversion program is executed by a processor, the above MPPT bus method is implemented.
[0059] The MPPT busbar circuit provided by the embodiment of the present invention includes N maximum power point tracking (MPPT) circuits and N - 1 busbar switch groups, where N is an integer greater than or equal to 2; the input end of each MPPT circuit is connected to a photovoltaic power generation component, and the output ends of each MPPT circuit are connected in parallel to the DC bus; among them, the N - 1 busbar switch groups are respectively connected to N - 1 MPPT circuits, and each busbar switch group includes a first switch tube and a second switch tube; the first end of the first switch tube of each busbar switch group is connected to the first end of the second switch tube, the second end of the first switch tube is connected to the input end of the MPPT circuit connected to this busbar switch group, and the second end of the second switch tube is connected to the input end of the next MPPT circuit arranged in sequence; among them, the polarities of the first end of the first switch tube and the first end of the second switch tube are the same, and the polarities of the second end of the first switch tube and the second end of the second switch tube are the same; the energy of multiple photovoltaic power generation components is busbar-connected to at least one MPPT circuit by controlling the conduction or cut-off of the first switch tube and the second switch tube of each busbar switch group through a control signal. In this way, in low-light scenarios, the MPPT busbar circuit can busbar-connect multiple photovoltaic power generation components to one or several MPPT circuits, extend the all-day grid-connected time of the photovoltaic inverter, and at the same time avoid the MPPT circuit from operating in a small-current scenario, reduce the number of starting circuits of the MPPT circuit in low-light scenarios, thereby reducing losses and maximizing the utilization of the energy of the photovoltaic power generation components.
[0060] Those skilled in the art should understand that the embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0061] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for realizing the functions specified in Figure 1 one or more of these processes or multiple processes and / or blocks Figure 1 one or more of these blocks or multiple blocks.
[0062] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including instruction means embodying the functionality specified in one or more of the flows Figure 1 a flow or flows and / or boxes Figure 1 specified in one or more of the boxes.
[0063] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the functionality specified in one or more of the flows Figure 1 a flow or flows and / or boxes Figure 1 specified in one or more of the boxes.
[0064] The specific embodiments described above further elaborate on the objectives, technical solutions, and beneficial effects of the present invention. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.
Claims
1. An MPPT busbar circuit, characterized in that: It comprises N maximum power point tracking MPPT circuits and N-1 bus switch groups, where N is an integer greater than or equal to 2; the input end of each MPPT circuit is connected to a photovoltaic power generation component, and the output end of each MPPT circuit is connected in parallel to a DC bus; Wherein, the N-1 bus switch groups are respectively connected to the N-1 MPPT circuits, and each of the bus switch groups includes a first switch tube and a second switch tube; the first end of the first switch tube of each bus switch group is connected to the first end of the second switch tube, the second end of the first switch tube is connected to the input end of the MPPT circuit connected to the bus switch group, and the second end of the second switch tube is connected to the input end of the next MPPT circuit arranged in sequence; wherein the first end of the first switch tube has the same polarity as the first end of the second switch tube, and the second end of the first switch tube has the same polarity as the second end of the second switch tube; The control signal is used to control the on or off of the first switch tube and the second switch tube of each of the bus switch groups to bus the energy of multiple photovoltaic power generation components to at least one MPPT circuit.
2. The MPPT bus circuit according to claim 1, characterized in that: The MPPT busbar circuit further includes N-1 interlocking drive circuits, each of which is connected to one of the busbar switch groups and is used to control the on or off of the first switch tube and the second switch tube of each busbar switch group according to a control signal; The first switch tube and the second switch tube of each bus switch group are not turned on at the same time.
3. The MPPT bus circuit according to claim 2, characterized in that: Each of the interlock drive circuits includes a first photoelectric coupler, a second photoelectric coupler, a first logic gate module and a second logic gate module; Among them, the first logic gate module includes a first AND gate, a first NOT gate and a first buffer gate, and the second logic gate module includes a second AND gate, a second NOT gate and a second buffer gate; the first buffer gate input end is connected to the second NOT gate input end for receiving a first control signal; the first NOT gate input end is connected to the second buffer gate input end for receiving a second control signal; the first buffer gate output end and the first NOT gate output end are respectively connected to the two input ends of the first AND gate, the second buffer gate output end and the second NOT gate output end are respectively connected to the two input ends of the second AND gate, the first AND gate output end is connected to the third end of the first switch tube through the first photoelectric coupler, the second AND gate output end is connected to the third end of the second switch tube through the second photoelectric coupler, and the third end of the first switch tube has the same polarity as the third end of the second switch tube.
4. The MPPT bus circuit according to claim 1, characterized in that: Each of the MPPT circuits detects the output current of the photovoltaic power generation assembly connected to the MPPT circuit, determines whether the MPPT circuit operates independently based on the output current of the photovoltaic power generation assembly connected to the MPPT circuit, and sends a control signal to control the conduction or closing of the first switch tube and the second switch tube of the bus switch group connected to the MPPT circuit.
5. The MPPT bus circuit according to claim 1, characterized in that: The MPPT bus circuit also includes a control unit, which is used to obtain the output current of the photovoltaic power generation assembly connected to each MPPT circuit, determine whether the MPPT circuit is operating independently according to the output current of the photovoltaic power generation assembly connected to each MPPT circuit, and send a control signal to control the conduction or closing of the first switch tube and the second switch tube of the bus switch group connected to each MPPT circuit.
6. A MPPT converging method, characterized in that: Applied to the MPPT busbar circuit according to any one of claims 1 to 5, the method comprises: According to the output current of the photovoltaic power generation components connected to each MPPT circuit, it is determined whether the MPPT circuit is operating independently and a control signal is issued; The first switch tube and the second switch tube of the bus switch group connected to each MPPT circuit are controlled to be turned on or off according to the control signal, so as to converge the energy of multiple photovoltaic power generation components to at least one MPPT circuit.
7. The MPPT converging method according to claim 6, characterized in that: According to the output current of the photovoltaic power generation components connected to each MPPT circuit, it is judged whether the MPPT circuit is operating independently, including: The output current of the photovoltaic power generation assembly connected to each MPPT circuit is compared with the preset MPPT bus current interval. When the output current of the photovoltaic power generation assembly connected to any MPPT circuit is within the MPPT bus current interval, the MPPT circuit operates independently. When the output current of the photovoltaic power generation assembly connected to any MPPT circuit is less than the minimum boundary threshold of the MPPT bus current interval, the MPPT circuit will not operate independently; If the output current of the photovoltaic power generation assembly connected to any MPPT circuit is greater than the maximum boundary threshold of the MPPT bus current interval, the output current of the photovoltaic power generation assembly connected to other MPPT circuits will be compared with the maximum boundary threshold. When the output current of the photovoltaic power generation assembly connected to other MPPT circuits is greater than or equal to the maximum boundary threshold, the MPPT circuit will operate independently; when the output current of the photovoltaic power generation assembly connected to other MPPT circuits is less than the maximum boundary threshold, the MPPT circuit will operate independently, and the output current of the photovoltaic power generation assembly connected to the MPPT circuit will be diverted to the bus of other MPPT circuits.
8. The MPPT converging method according to claim 7, characterized in that: The MPPT bus current interval is set according to the efficiency curve of the MPPT circuit.
9. A photovoltaic inverter, characterized in that: It comprises an inverter circuit and an MPPT bus circuit as claimed in any one of claims 1 to 5; Among them, the input side of the MPPT bus circuit is connected to multiple photovoltaic power generation components, and the output side of the MPPT bus circuit is connected to the inverter circuit through a DC bus; the MPPT bus circuit is used to converge the energy of multiple photovoltaic power generation components to at least one MPPT circuit and input it into the inverter circuit.
10. A photovoltaic power generation system, characterized in that: Comprising the photovoltaic inverter as claimed in claim 9.