Photovoltaic optimizer control method, device and system

Abstract

The invention discloses a photovoltaic optimizer control method, device and system, and the method comprises the steps: carrying out the maximum power point tracking of a photovoltaic optimizer according to an initial duty ratio after the photovoltaic optimizer is started, and obtaining a first actual duty ratio corresponding to the first target output power when the photovoltaic optimizer reaches the first target output power; when the first actual duty ratio is not smaller than the initial duty ratio, the photovoltaic optimizer is controlled to enter a direct connection mode, and the actual output power in the direct connection mode is obtained; performing maximum power point tracking on the photovoltaic optimizer again according to the first actual duty ratio in the direct connection mode every first preset time so as to obtain second target output power; and when the second target output power is greater than the actual output power, taking a second actual duty ratio corresponding to the second target output power as the initial duty ratio. According to the invention, the problem of low power generation gain caused by switching the working mode of the photovoltaic optimizer according to the fixed power threshold can be effectively relieved.

Description

Technical Field

[0001] The present application relates to the field of electronic technology, and in particular to a photovoltaic optimizer control method, device and system. Background Art

[0002] As the primary control component for improving photovoltaic panel power generation efficiency, the photovoltaic optimizer significantly mitigates the impact of inefficiencies caused by factors such as shading and inconsistent photovoltaic orientation. Its core function is to utilize a maximum power point tracking (MPPT) algorithm to maintain the panel's current maximum power output even in the presence of shading. This avoids the "barrel effect" caused by connecting other panels with lower power output in series, thereby improving the power generation efficiency of the entire string or photovoltaic power station.

[0003] When the ratio of output power to input power is large, the switching frequency increases due to the power characteristics of the buck circuit topology. Due to the inherent characteristics of the switching tube, switching losses also increase, exacerbating the optimizer's energy loss to photovoltaic power generation and ultimately reducing the overall power generation gain. Furthermore, increased switching losses also shorten the lifespan of the switching electronic components, thereby reducing the overall service life of the optimizer.

[0004] The current response is to switch the optimizer from MPPT mode to direct mode through power judgment. The principle is: when the photovoltaic panel generates high power, the output-input voltage ratio is large, and the switching loss is also large. The control method is to set a power threshold. If a certain threshold is exceeded, the corresponding algorithm will turn on the upper tube and turn off the lower tube in the buck circuit, that is, direct mode, thereby reducing switching losses and thus reducing the energy loss of the optimizer itself, thereby improving power generation gain. However, the current mode switching relies on a fixed power threshold (such as setting a certain power value to trigger direct mode). However, the photovoltaic output is dynamically affected by environmental factors (such as temperature and irradiance). Fixed thresholds can easily lead to untimely mode switching or false triggering (such as in scenes with alternating cloudy and sunny weather), reducing power generation gain.

[0005] Therefore, the current technology still needs to be improved and enhanced. Summary of the Invention

[0006] The present application provides a photovoltaic optimizer control method, device and system, which can effectively alleviate the problem of low power generation gain caused by switching the photovoltaic optimizer working mode according to a fixed power threshold.

[0007] The present application provides a photovoltaic optimizer control method, which includes:

[0008] After the photovoltaic optimizer is started, maximum power point tracking is performed on the photovoltaic optimizer according to the initial duty cycle, and when the photovoltaic optimizer reaches a first target output power, a first actual duty cycle corresponding to the first target output power is obtained;

[0009] When the first actual duty cycle is not less than the initial duty cycle, the photovoltaic optimizer is controlled to enter the direct mode and the actual output power in the direct mode is obtained;

[0010] In the direct mode, at intervals of a first preset time, the photovoltaic optimizer is again subjected to maximum power point tracking according to the first actual duty cycle to obtain a second target output power;

[0011] When the second target output power is greater than the actual output power, the second actual duty cycle corresponding to the second target output power is used as the initial duty cycle.

[0012] In some embodiments, the photovoltaic optimizer control method further includes, after the step of obtaining the first actual duty cycle corresponding to the first target output power:

[0013] When the first actual duty cycle is less than the initial duty cycle, the photovoltaic optimizer is maintained in a maximum power point tracking state.

[0014] In some embodiments, the photovoltaic optimizer control method further includes, after the step of performing maximum power point tracking on the photovoltaic optimizer again according to the first actual duty cycle to obtain the second target output power:

[0015] When the second target output power is not greater than the actual output power, the photovoltaic optimizer is controlled to enter the direct mode.

[0016] In some embodiments, the photovoltaic optimizer control method includes the steps of controlling the photovoltaic optimizer to enter a direct mode when the first actual duty cycle is not less than the initial duty cycle, and obtaining the actual output power in the direct mode.

[0017] When the first actual duty cycle is not less than the initial duty cycle, the photovoltaic optimizer is controlled to enter the direct mode;

[0018] Obtain the target output voltage, loss current, and line loss power of the PV optimizer in direct mode;

[0019] Calculates the actual output power based on the target output voltage, current loss, and line power loss.

[0020] In some embodiments, the photovoltaic optimizer control method includes the following steps: when the second target output power is greater than the actual output power, using the second actual duty cycle corresponding to the second target output power as the initial duty cycle, and performing maximum power point tracking on the photovoltaic optimizer based on the updated initial duty cycle.

[0021] Obtain the switching loss power of the photovoltaic optimizer and calculate the reference power based on the switching loss power and the actual output power;

[0022] When the second target output power is greater than the reference power, the second actual duty cycle corresponding to the second target output power is used as the initial duty cycle.

[0023] In some embodiments, a photovoltaic optimizer control method includes performing maximum power point tracking on the photovoltaic optimizer according to an initial duty cycle, and when the photovoltaic optimizer reaches a first target output power, obtaining a first actual duty cycle corresponding to the first target output power, including:

[0024] Obtain the initial duty cycle and duty cycle disturbance step of the photovoltaic optimizer, and obtain the current input voltage and current output voltage of the photovoltaic optimizer in real time;

[0025] Perform maximum power point tracking on the photovoltaic optimizer according to the initial duty cycle and duty cycle perturbation step size at a preset period;

[0026] When the photovoltaic optimizer reaches the first target output power, a first actual duty cycle is calculated according to the current output voltage and the current input voltage.

[0027] In some embodiments of the photovoltaic optimizer control method, the power change value before and after the duty cycle disturbance step adjustment is less than a preset convergence value.

[0028] In some embodiments, the photovoltaic optimizer control method further includes, before the step of performing maximum power point tracking on the photovoltaic optimizer according to the initial duty cycle and obtaining a first actual duty cycle corresponding to the first target output power when the photovoltaic optimizer reaches the first target output power:

[0029] obtaining the ambient temperature and average irradiance intensity of the photovoltaic optimizer at intervals of a second preset time;

[0030] Determine whether the photovoltaic optimizer meets the update conditions of the initial duty cycle based on the ambient temperature and average irradiation intensity;

[0031] When the change in ambient temperature or average irradiance intensity is greater than a preset deviation value, the update condition for the initial duty cycle is met.

[0032] An embodiment of the present application further provides a photovoltaic optimizer control device, which includes a controller and a photovoltaic optimizer. The controller is connected to the photovoltaic optimizer, and the controller is used to execute the above-mentioned photovoltaic optimizer control method.

[0033] An embodiment of the present application also provides a photovoltaic optimizer control system, which includes a photovoltaic panel, a load and the above-mentioned photovoltaic optimizer control device, wherein the input end of the photovoltaic optimizer is connected to the photovoltaic panel, and the output end of the photovoltaic optimizer is connected to the load.

[0034] The present application provides a photovoltaic optimizer control method, device, and system. The photovoltaic optimizer control method uses the duty cycle as a basis for determining whether the photovoltaic optimizer enters the direct mode. After controlling the photovoltaic optimizer to enter the direct mode, the maximum power point tracking will be performed again after a period of time. This process facilitates the updating of the duty cycle, ensuring that the duty cycle can change dynamically, thereby optimizing the working state of the switching element, thereby reducing switching losses. At the same time, the photovoltaic optimizer does not need to switch between the direct mode and the maximum power point tracking mode based on a fixed power value, but flexibly switches with the dynamically changing duty cycle, so that the photovoltaic optimizer can switch the working mode in time under different environmental conditions. At the same time, it can also alleviate the false triggering phenomenon that exists when the fixed power threshold is used as the switching basis, ensuring the power generation gain of the photovoltaic panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and other beneficial effects of the present application apparent.

[0036] Figure 1 This is a structural block diagram of the photovoltaic optimizer control system provided in an embodiment of the present application.

[0037] Figure 2 This is a first circuit structure diagram of the photovoltaic optimizer in the photovoltaic optimizer control system provided in an embodiment of the present application.

[0038] Figure 3 This is a second circuit structure diagram of the photovoltaic optimizer in the photovoltaic optimizer control system provided in an embodiment of the present application.

[0039] Figure 4 This is a schematic diagram of the first flow chart of the photovoltaic optimizer control method provided in an embodiment of the present application.

[0040] Figure 5 This is a flow chart of step 100 in the photovoltaic optimizer control method provided in an embodiment of the present application.

[0041] Figure 6 This is a flow chart of step 200 in the photovoltaic optimizer control method provided in an embodiment of the present application.

[0042] Figure 7 This is a flow chart of step 400 in the photovoltaic optimizer control method provided in an embodiment of the present application.

[0043] Figure 8A second flow chart of the photovoltaic optimizer control method provided in an embodiment of the present application.

[0044] Figure 9 This is a schematic diagram of a third flow chart of the photovoltaic optimizer control method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0046] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or suggesting relative importance or implicitly indicating the number of technical features indicated. The features specified as "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0047] See also Figure 1 The embodiment of the present application provides a photovoltaic optimizer 14 control system, which includes a photovoltaic panel 11, a load 12, and a photovoltaic optimizer control device. The photovoltaic optimizer control device includes a controller 13 and a photovoltaic optimizer 14. The controller 13 is connected to the photovoltaic optimizer 14. The input end of the photovoltaic optimizer 14 is connected to the photovoltaic panel 11, and the output end of the photovoltaic optimizer 14 is connected to the load 12. The photovoltaic panel 11 is a device that converts solar energy into electrical energy. The photovoltaic optimizer 14 can optimize the output power of the photovoltaic module to solve the problem of reduced power generation due to problems such as shadow obstruction, inconsistent module orientation, or inconsistent module attenuation. The photovoltaic module in this embodiment is the photovoltaic panel 11.

[0048] See also Figure 2The main power circuit of the photovoltaic optimizer 14 uses a buck circuit, which includes a first field-effect transistor (FET) Q1, a second field-effect transistor (FET) Q2, an inductor L1, a first capacitor C1, and a second capacitor C2. The drain of the first field-effect transistor Q1 is connected to the positive electrode of the photovoltaic panel 11, the source of the first field-effect transistor Q1 is connected to one end of the inductor L1 and the drain of the second field-effect transistor Q2, the other end of the inductor L1 is connected to one end of the second capacitor C2 and one end of the load 12, the source of the second field-effect transistor Q2 is connected to the negative electrode of the photovoltaic panel 11, the other end of the second capacitor C2 is connected to the negative electrode of the photovoltaic panel 11 and the other end of the load 12, one end of the first capacitor C1 is connected to the positive electrode of the photovoltaic panel 11, and the other end of the first capacitor C1 is connected to the negative electrode of the photovoltaic panel 11. The gates of the first field-effect transistor Q1 and the second field-effect transistor Q2 are both connected to the controller 13 for receiving control signals with a certain duty cycle.

[0049] The operating principle of the photovoltaic optimizer 14 is as follows: the first FET Q1 and the second FET Q2 receive complementary control signals, such as PWM signals. When the first FET Q1 is on, the second FET Q2 is off, charging the inductor L1 and increasing the current in the inductor L1. When the first FET Q1 is off and the second FET Q2 is on, the current in the inductor L1 cannot change suddenly, so the current supplies power to the load 12, and the current in the inductor L1 decreases. Control signals with different duty cycles can control the voltage, current, and power of the photovoltaic optimizer 14.

[0050] When the photovoltaic panel 11 generates a high power, the output-input voltage ratio is large, and the switching loss is also large. The control method is to set a power threshold. If it exceeds a certain threshold, the upper tube in the BUCK circuit will be turned on and the lower tube will be turned off through the corresponding algorithm, that is, the direct mode, thereby reducing the switching loss, thereby reducing the energy loss of the optimizer itself and improving the power generation gain. In the direct mode, when the first field effect tube Q1 is fully turned on and the second field effect tube Q2 is turned off, the first field effect tube Q1 is equivalent to a wire and the second field effect tube Q2 is turned off. At this time, the main power circuit of the photovoltaic optimizer 14 is equivalent to Figure 3 circuit structure.

[0051] See also Figure 4 , the embodiment of the present application further provides a photovoltaic optimizer control method, the photovoltaic optimizer control method comprising:

[0052] 100. After the photovoltaic optimizer is started, maximum power point tracking is performed on the photovoltaic optimizer according to the initial duty cycle, and when the photovoltaic optimizer reaches a first target output power, a first actual duty cycle corresponding to the first target output power is obtained;

[0053] 200. When the first actual duty cycle is not less than the initial duty cycle, controlling the photovoltaic optimizer to enter a direct mode and obtaining an actual output power in the direct mode;

[0054] 300. In the direct mode, at intervals of a first preset time, perform maximum power point tracking on the photovoltaic optimizer again according to the first actual duty cycle to obtain a second target output power;

[0055] 400. When the second target output power is greater than the actual output power, use the second actual duty cycle corresponding to the second target output power as the initial duty cycle.

[0056] In this embodiment, after the PV optimizer is started, maximum power point tracking (MPP) is performed on the PV optimizer based on its initial duty cycle. When the PV optimizer reaches a first target output power through MPP tracking, a first actual duty cycle at the first target output power is obtained. The first actual duty cycle is then compared with the initial duty cycle. If the first actual duty cycle is not less than the initial duty cycle, the PV optimizer is controlled to enter pass-through mode, which fully turns on the first field-effect transistor (FET) and completely turns off the second field-effect transistor (FET), terminating maximum power point tracking. This is equivalent to disabling the high-frequency PWM control signal, reducing switching losses to approximately zero. In this embodiment, whether the PV optimizer enters pass-through mode is determined based on the initial duty cycle, rather than a fixed power threshold.

[0057] When the photovoltaic optimizer operates in the direct-flow mode, it is also necessary to obtain the actual output power of the photovoltaic optimizer in the direct-flow mode. After the photovoltaic optimizer operates in the direct-flow mode for a first preset time, the photovoltaic optimizer is controlled to exit the direct-flow mode and enter the maximum power point tracking mode. That is, the photovoltaic optimizer is again subjected to maximum power point tracking based on the first actual duty cycle. After this maximum power point tracking, a second target output power is obtained. The second target output power is then compared with the actual output power. If the second target output power is greater than the actual output power, the second actual duty cycle corresponding to the second target output power is recorded and saved as the initial duty cycle. This is equivalent to updating the initial duty cycle, so that maximum power point tracking can continue according to the updated initial duty cycle. The updated initial duty cycle is used as the basis for whether to control the photovoltaic optimizer to enter the direct-flow mode next time.

[0058] In this embodiment, the duty cycle is used as a basis for determining whether the photovoltaic optimizer enters the direct mode. After the photovoltaic optimizer enters the direct mode, maximum power point tracking is performed again after a certain period of time. This process facilitates the updating of the duty cycle, ensuring that the duty cycle can change dynamically, thereby optimizing the operating state of the switching elements and reducing switching losses. At the same time, the photovoltaic optimizer switches between the direct mode and maximum power point tracking mode without relying on a fixed power value. Instead, it switches flexibly with the dynamically changing duty cycle, allowing the photovoltaic optimizer to switch operating modes in a timely manner under different environmental conditions. This also mitigates the false triggering phenomenon that occurs when a fixed power threshold is used as the switching basis, ensuring the power generation gain of the photovoltaic panel.

[0059] In some embodiments, the photovoltaic optimizer performs maximum power point tracking based on the initial duty cycle. When the photovoltaic optimizer reaches a first target output power, a first actual duty cycle corresponding to the first target output power is obtained, and the first actual duty cycle is compared with the initial duty cycle. When the first actual duty cycle is not less than the initial duty cycle, the photovoltaic optimizer is controlled to enter a pass-through mode. Conversely, when the first actual duty cycle is less than the initial duty cycle, the photovoltaic optimizer is maintained in the maximum power point tracking state and the maximum power point tracking operation continues.

[0060] In some embodiments, the photovoltaic optimizer is again subjected to maximum power point tracking based on the first actual duty cycle to obtain a second target output power. The second target output power is then compared with the actual output power. If the second target output power is greater than the actual output power, the second actual duty cycle corresponding to the second target output power is used as the initial duty cycle for maximum power point tracking of the photovoltaic optimizer. Conversely, if the second target output power is less than or equal to the actual output power, the photovoltaic optimizer is controlled to enter a pass-through mode.

[0061] See also Figure 5 As an embodiment, step 100 includes:

[0062] 110. Obtain an initial duty cycle and a duty cycle disturbance step size of the photovoltaic optimizer, and obtain a current input voltage and a current output voltage of the photovoltaic optimizer in real time;

[0063] 120. Perform maximum power point tracking on the photovoltaic optimizer according to the initial duty cycle and the duty cycle disturbance step size according to a preset period;

[0064] 130. When the photovoltaic optimizer reaches a first target output power, a first actual duty cycle is calculated according to a current output voltage and a current input voltage.

[0065] Among them, the current input voltage of the photovoltaic optimizer corresponds to the current output voltage of the photovoltaic panel. After the photovoltaic optimizer is started, the initial duty cycle and the duty cycle perturbation step of the photovoltaic optimizer are obtained, and the maximum power point tracking of the photovoltaic optimizer is performed according to the duty cycle perturbation step at a preset period. When the first target output power is reached after the maximum power point tracking, the first actual duty cycle is calculated based on the current output voltage and the current input voltage. Denote the current input voltage, i.e., the current output voltage of the photovoltaic panel, as Vpv, denote the current output voltage of the photovoltaic optimizer as Vout1, and denote the first actual duty cycle as D1. Then D1 = Vout1 / Vpv.

[0066] Since when performing the maximum power point tracking perturbation, if the duty cycle perturbation step is too large, the impact on the BUCK circuit is too great, which may cause the tracking point to "fly randomly" and get out of control; if the duty cycle perturbation step is too small, the impact on the BUCK circuit is too small, which may cause the tracking speed to be too slow. Therefore, a suitable duty cycle perturbation step needs to be set. As an embodiment, the power change value before and after adjusting the duty cycle perturbation step is less than a preset convergence value. Specifically, during the process of performing the maximum power point tracking on the photovoltaic optimizer according to the duty cycle perturbation step at a preset period, apply the duty cycle perturbation step ΔD = Dstep, and then calculate the power change value ΔP = Pnew – Pold, where Pnew is the output power after applying the duty cycle perturbation step, and Pold is the output power before applying the duty cycle perturbation step. The setting of the duty cycle perturbation step needs to satisfy |ΔP| < Ptol, where Ptol is the preset convergence value, thereby ensuring a better maximum power point tracking effect.

[0067] Please refer to Figure 6 , as an embodiment, step 200 includes:

[0068] 210. When the first actual duty cycle is not less than the initial duty cycle, control the photovoltaic optimizer to enter the direct connection mode;

[0069] 220. Obtain the target output voltage, loss current, and line loss power of the photovoltaic optimizer in the direct connection mode;

[0070] 230. Calculate the actual output power based on the target output voltage, loss current, and line loss power.

[0071] The target output voltage in the pass-through mode is Vout2, the line loss current is Iload, the line loss power is Ploss, and the actual output power is Pbypass; where the line loss power is pre-stored. When the first actual duty cycle is not less than or greater than the initial duty cycle, the mode switch is triggered, and the photovoltaic optimizer is controlled to enter the pass-through mode. It is also necessary to obtain the actual output power in the pass-through mode. In order to improve the accuracy of the regulation during the calculation process, line loss must also be considered. Therefore, in this embodiment, when calculating the actual output power, the line loss power needs to be excluded, and the corresponding Pbypass = Vout 2·Iload-Ploss.

[0072] See also Figure 7 As an embodiment, step 400 includes:

[0073] 410. Obtain switching loss power of the photovoltaic optimizer, and calculate a reference power based on the switching loss power and the actual output power;

[0074] 420. When the second target output power is greater than the reference power, use a second actual duty cycle corresponding to the second target output power as the initial duty cycle.

[0075] In this embodiment, when comparing the second target output power with the actual output power, the switching loss power can also be taken into account. The switching loss power is recorded as Psw_loss, the second target output power is recorded as Pmppt, and the switching loss power and the actual output power are added together to obtain the reference power. Afterwards, the second target output power is compared with the reference power. If the second target output power is greater than the reference power, the second actual duty cycle corresponding to the second target output power is recorded as the initial duty cycle for maximum power point tracking; if the second target output power is not greater than the reference power, the photovoltaic optimizer is controlled to enter the direct mode. That is, if Pmppt>Pbypass+Psw_loss, the initial duty cycle is updated, and the second actual duty cycle is used as the initial duty cycle; if Pmppt<=Pbypass+Psw_loss, the current initial duty cycle is maintained unchanged, and the direct mode is immediately returned to reduce the switching loss.

[0076] See also Figure 8 In some embodiments, before step 100, the method further includes:

[0077] 10. Obtain the ambient temperature and average irradiance intensity of the photovoltaic optimizer at every second preset time interval;

[0078] 20. Determine whether the photovoltaic optimizer meets the update conditions of the initial duty cycle based on the ambient temperature and average irradiation intensity;

[0079] 30. When the change in ambient temperature or average radiation intensity is greater than the preset deviation value, the update condition of the initial duty cycle is met.

[0080] To ensure that the dynamic initial duty cycle can be adaptively adjusted over the long term, the ambient temperature and average irradiance intensity of the photovoltaic optimizer are obtained at intervals of a second preset time. The photovoltaic optimizer determines whether it meets the initial duty cycle update conditions based on the ambient temperature or average irradiance intensity. In this embodiment, the photovoltaic optimizer control process also detects and stores the ambient temperature and average irradiance intensity. If the ambient temperature or average irradiance intensity changes to a certain extent and the change is greater than a preset deviation value, it indicates that the environment in which the photovoltaic optimizer is located has changed, such as when the photovoltaic optimizer is in a low-power, rainy, or sunny day, or when the light fluctuates rapidly. This indicates that the initial duty cycle update conditions are met and the initial duty cycle needs to be adjusted according to changes in the environmental scene. Then, after the photovoltaic optimizer is started, the process of dynamically updating the initial duty cycle is executed. The specific process of dynamically updating the initial duty cycle is as described in steps 100, 200, 300, and 400 above. Since the dynamic update process of the initial duty cycle has been described in detail above, it will not be repeated here.

[0081] In order to describe the photovoltaic optimizer control method in this application in detail, the photovoltaic optimizer control method is illustrated below with reference to specific embodiments:

[0082] After the optimizer starts up normally, it obtains the current input voltage, output voltage, and current of the PV optimizer and sets an initial duty cycle. This initial duty cycle can also be the updated initial duty cycle from the last startup of the PV optimizer. Maximum power point tracking (MPP) is then performed. When the maximum power point is reached, the system determines whether the current duty cycle is greater than the initial duty cycle, and then selectively enters either MPPT mode or shoot-through mode. After entering shoot-through mode, the system enters MPPT mode after a certain period of time to find the maximum power point. If the current power is greater than the sum of the shoot-through power and the power loss, the current duty cycle is recorded and updated as the initial duty cycle, which serves as the basis for determining whether to enter shoot-through mode the next time. Otherwise, the system reverts to shoot-through mode to reduce switching losses.

[0083] See also Figure 9 , the specific steps are as follows:

[0084] S10, obtaining the input voltage and output voltage of the photovoltaic optimizer and the output current of the photovoltaic panel;

[0085] S20, obtaining an initial duty cycle;

[0086] S30, performing maximum power point tracking;

[0087] S40. Determine whether the first target output power is reached; if so, execute step S50; if not, return to step S30;

[0088] S50. Determine whether the first actual duty cycle is greater than or equal to the initial duty cycle; if so, execute step 60; if not, return to step S30;

[0089] S60. Enter the direct-through mode;

[0090] S70. After the first preset time, exit the direct-through mode and perform maximum power point tracking to obtain the second target output power;

[0091] S80. Calculate the actual output power and reference power in the direct-through mode;

[0092] S90. Determine whether the second target output power is greater than the reference power; if so, execute step 100; if not, return to step S60;

[0093] S100. Record the second actual duty cycle corresponding to the second target output power and update the initial duty cycle.

[0094] In the photovoltaic optimizer control method of this embodiment, first, the process of system initialization and parameter setting will start: after the photovoltaic optimizer is started, hardware self-check is completed, and the output voltage of the photovoltaic panel, the input voltage of the photovoltaic optimizer, the output current of the photovoltaic panel, and the output voltage of the photovoltaic optimizer are obtained. Then, the initial duty cycle is obtained. If the photovoltaic optimizer is started for the first time, the initial duty cycle can be a default set value. If the photovoltaic optimizer is not started for the first time, the initial duty cycle can also be the historical data stored in the photovoltaic optimizer, and the initial duty cycle updated last time is directly called.

[0095] After the system initialization and parameter setting process is completed, the maximum power point tracking and duty cycle determination process are carried out: the duty cycle perturbation step size is applied at a preset period, and the output power change is calculated to complete the maximum power point tracking process. Among them, according to the duty cycle perturbation step size in the perturbation process, the power change value needs to be less than the preset convergence value to facilitate the implementation of an efficient maximum power point tracking process. When the maximum power point tracking process converges to the maximum power point, that is, the first target output power is obtained, and then the current duty cycle, that is, the first actual duty cycle corresponding to the first target output power, is calculated. The sizes of the actual duty cycle and the initial duty cycle are judged. Denote the initial duty cycle as Dth and the first actual duty cycle as D1. If D1 < Dth, the maximum power point tracking mode is maintained and the periodic perturbation continues; if D1 >= Dth, the mode switching is triggered to control the photovoltaic optimizer to enter the direct-through mode.

[0096] Afterwards, the pass-through mode operation and initial duty cycle update process are performed: When the photovoltaic optimizer is controlled to enter the pass-through mode, the first field-effect transistor is forced to conduct, the second field-effect transistor is completely disconnected, and the maximum power point tracking disturbance is stopped. This is equivalent to stopping the output of the PWM control signal, reducing the switching loss to approximately zero. Then, the maximum power point detection process is periodically returned to, briefly exiting the pass-through mode at intervals of a first preset time, restarting the maximum power point tracking algorithm, and re-obtaining the current maximum power point to obtain the second target output power Pmppt. At the same time, the actual output power in the pass-through mode is calculated as Pbypass = Vout·Iload-Ploss. If Pmppt>Pbypass+Psw_loss, the current duty cycle, i.e., the second actual duty cycle D2 corresponding to the second target output power, is recorded, the initial duty cycle Dth is updated to D2, and the maximum power point tracking mode is switched based on the updated initial duty cycle to continue optimizing the output power of the photovoltaic panel. If Pmppt<=Pbypass+Psw_loss, the current initial duty cycle is kept unchanged and the system returns to the pass-through mode immediately, thereby realizing the dynamic update process of the initial duty cycle. While reducing the switching loss, the PV optimizer can be controlled in time to switch modes. At the same time, it can also alleviate the problem of reduced power generation gain caused by false triggering due to the fixed power threshold as the switching basis.

[0097] The embodiment of the present application further provides a photovoltaic optimizer control device. Since the photovoltaic optimizer control device has been described in detail above, it will not be described again here.

[0098] The embodiment of the present application further provides a photovoltaic optimizer control method. Since the photovoltaic optimizer control method has been described in detail above, it will not be repeated here.

[0099] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0100] The photovoltaic optimizer control method provided in the embodiments of the present application is introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A photovoltaic optimizer control method, characterized in that: The photovoltaic optimizer control method includes: After the photovoltaic optimizer is started, performing maximum power point tracking on the photovoltaic optimizer according to the initial duty cycle, and when the photovoltaic optimizer reaches a first target output power, obtaining a first actual duty cycle corresponding to the first target output power; When the first actual duty cycle is not less than the initial duty cycle, controlling the photovoltaic optimizer to enter a direct mode and obtaining the actual output power in the direct mode; In the direct mode, at intervals of a first preset time, performing maximum power point tracking on the photovoltaic optimizer again according to the first actual duty cycle to obtain a second target output power; When the second target output power is greater than the actual output power, a second actual duty cycle corresponding to the second target output power is used as the initial duty cycle.

2. The photovoltaic optimizer control method according to claim 1, characterized in that: After the step of obtaining the first actual duty cycle corresponding to the first target output power, the method further includes: When the first actual duty cycle is less than the initial duty cycle, the photovoltaic optimizer is maintained in a maximum power point tracking state.

3. The photovoltaic optimizer control method according to claim 1, characterized in that: After the step of performing maximum power point tracking on the photovoltaic optimizer again according to the first actual duty cycle to obtain the second target output power, the step further includes: When the second target output power is not greater than the actual output power, the photovoltaic optimizer is controlled to enter the direct mode.

4. The photovoltaic optimizer control method according to claim 1, characterized in that: When the first actual duty cycle is not less than the initial duty cycle, the step of controlling the photovoltaic optimizer to enter the direct mode and obtaining the actual output power in the direct mode includes: When the first actual duty cycle is not less than the initial duty cycle, controlling the photovoltaic optimizer to enter a direct mode; Obtaining a target output voltage, a loss current, and a line loss power of the photovoltaic optimizer in the direct mode; The actual output power is calculated according to the target output voltage, the loss current, and the line loss power.

5. The photovoltaic optimizer control method according to claim 4, characterized in that: When the second target output power is greater than the actual output power, the steps of using the second actual duty cycle corresponding to the second target output power as the initial duty cycle, and performing maximum power point tracking on the photovoltaic optimizer according to the updated initial duty cycle include: Obtaining the switching loss power of the photovoltaic optimizer, and calculating a reference power according to the switching loss power and the actual output power; When the second target output power is greater than the reference power, a second actual duty cycle corresponding to the second target output power is used as the initial duty cycle.

6. The photovoltaic optimizer control method according to claim 1, characterized in that: The step of performing maximum power point tracking on the photovoltaic optimizer according to the initial duty cycle and obtaining a first actual duty cycle corresponding to a first target output power when the photovoltaic optimizer reaches the first target output power includes: Obtaining the initial duty cycle and duty cycle disturbance step of the photovoltaic optimizer, and obtaining the current input voltage and current output voltage of the photovoltaic optimizer in real time; Performing maximum power point tracking on the photovoltaic optimizer according to the initial duty cycle and the duty cycle disturbance step size at a preset period; When the photovoltaic optimizer reaches the first target output power, the first actual duty cycle is calculated according to the current output voltage and the current input voltage.

7. The photovoltaic optimizer control method according to claim 6, characterized in that: The power change value before and after the duty cycle disturbance step size adjustment is less than a preset convergence value.

8. The photovoltaic optimizer control method according to claim 6, characterized in that: Before the step of performing maximum power point tracking on the photovoltaic optimizer according to the initial duty cycle and obtaining a first actual duty cycle corresponding to a first target output power when the photovoltaic optimizer reaches the first target output power, the method further includes: obtaining the ambient temperature and average irradiance intensity of the photovoltaic optimizer at intervals of a second preset time; Determining whether the photovoltaic optimizer meets the update condition of the initial duty cycle according to the ambient temperature and the average irradiation intensity; When the change in the ambient temperature or the average irradiance intensity is greater than a preset deviation value, the update condition for the initial duty cycle is met.

9. A photovoltaic optimizer control device, characterized in that: The photovoltaic optimizer control device includes a controller and a photovoltaic optimizer, the controller is connected to the photovoltaic optimizer, and the controller is used to execute the photovoltaic optimizer control method according to any one of claims 1 to 8.

10. A photovoltaic optimizer control system, characterized in that: The photovoltaic optimizer control system includes a photovoltaic panel, a load, and the photovoltaic optimizer control device according to claim 9, wherein the input end of the photovoltaic optimizer is connected to the photovoltaic panel, and the output end of the photovoltaic optimizer is connected to the load.

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