Low light detection method, maximum power tracking circuit and photovoltaic system

Abstract

The application provides a weak light detection method, a maximum power tracking circuit and a photovoltaic system. The maximum power tracking circuit comprises an inductive energy storage unit and a switching unit. The first end of the inductive energy storage unit is connected with the input end of the maximum power tracking circuit, the second end of the inductive energy storage unit is connected with the output end of the maximum power tracking circuit, the first end of the switching unit is connected with the second end of the inductive energy storage unit, and the second end of the switching unit is grounded. The weak light detection method comprises the following steps: sending a first control signal with a first preset frequency to the switching unit, the first control signal being used for controlling the switching unit to be turned on at the first preset frequency so as to work in a linear region; obtaining a first current value flowing through the switching unit; and outputting a starting signal to the maximum power tracking circuit if the first current value is greater than or equal to a preset current threshold, the starting signal being used for controlling the maximum power tracking circuit to perform maximum power tracking. The above method can avoid the cyclic starting of the maximum power tracking circuit under weak light.

Description

Technical Field

[0001] This application relates to the field of new energy technology, specifically to low light detection methods, maximum power tracking circuits, and photovoltaic systems. Background Technology

[0002] In related technologies, photovoltaic systems are equipped with maximum power tracking circuits to track the maximum power generated by the photovoltaic panels and output the maximum power generated by the photovoltaic panels to the load side of the photovoltaic system.

[0003] However, when photovoltaic panels are exposed to weak light, the maximum power tracking circuit will be activated repeatedly, which will have an adverse effect on the maximum power tracking circuit. Summary of the Invention

[0004] In view of this, this application provides a weak light detection method, a maximum power tracking circuit, and a photovoltaic system, which can solve the problem of the maximum power tracking circuit cyclically starting up when the photovoltaic panel is illuminated by weak light.

[0005] The first aspect of this application provides a low-light detection method applied to a maximum power point tracking (MPPT) circuit. The MPPT circuit includes an inductor energy storage unit and a switching unit. A first terminal of the inductor energy storage unit is connected to the input terminal of the MPPT circuit, and a second terminal of the inductor energy storage unit is connected to the output terminal of the MPPT circuit. A first terminal of the switching unit is connected to the second terminal of the inductor energy storage unit, and the second terminal of the switching unit is grounded. The low-light detection method includes: sending a first control signal with a first preset frequency to the switching unit, the first control signal being used to control the switching unit to conduct at the first preset frequency to operate in the linear region; acquiring a first current value flowing through the switching unit; and if the first current value is greater than or equal to a preset current threshold, outputting a start signal to the MPPT circuit, the start signal being used to control the MPPT circuit to perform maximum power point tracking.

[0006] In this embodiment, before controlling the maximum power point tracking (MPPT) circuit to perform MPPT, a first control signal with a first preset frequency is sent to the switching unit to turn it on and operate in the linear region. This causes the first and second terminals of the switching unit to exhibit DC voltage characteristics, allowing the effective first current value of the photovoltaic input to the switching unit to be obtained from either the first or second terminal. After determining that the first current value is greater than or equal to a preset current threshold, the MPPT circuit is then controlled to perform MPPT via a start signal, effectively preventing the cyclic start-up of the MPPT circuit. Furthermore, the aforementioned weak light detection process is achieved by controlling the existing switching unit of the MPPT circuit to operate in the linear region, eliminating the need for additional detection circuits, detection devices, or detection equipment, thereby reducing the complexity of the photovoltaic system's circuit structure.

[0007] In one embodiment, the low light detection method further includes: if the first current value is less than a preset current threshold, then outputting a low light warning signal, which is used to remind the user that the current situation is under low light conditions.

[0008] In one embodiment, the low light detection method further includes: acquiring the input voltage of the maximum power tracking circuit; calculating the input power of the maximum power tracking circuit based on the input voltage and a first current value; and outputting a start signal to the maximum power tracking circuit when the input power is greater than or equal to a preset power threshold.

[0009] In one embodiment, the weak light detection method further includes: when the first control signal is not sent, sending a second control signal with a second preset frequency to the switching unit so that the switching unit operates in the saturation region, the second preset frequency being less than the first preset frequency, obtaining a second current value flowing through the inductor energy storage unit, and if the second current value is greater than or equal to a preset current threshold, outputting a start signal to the maximum power tracking circuit, the start signal being used to control the maximum power tracking circuit to perform maximum power tracking.

[0010] In one embodiment, the low light detection method further includes: acquiring the input voltage of the maximum power tracking circuit, calculating the input power of the maximum power tracking circuit based on the input voltage and the second current value, and outputting a start signal to the maximum power tracking circuit when the input power is greater than or equal to a preset power threshold.

[0011] A second aspect of this application provides a maximum power point tracking (MPPT) circuit, including an inductor energy storage unit, a switching unit, a filtering unit, and a controller. A first terminal of the inductor energy storage unit is connected to the input terminal of the MPPT circuit, and a second terminal of the inductor energy storage unit is connected to the output terminal of the MPPT circuit. A first terminal of the switching unit is connected to the second terminal of the inductor energy storage unit, and the second terminal of the switching unit is grounded. A first terminal of the filtering unit is connected to the input terminal of the MPPT circuit, and the second terminal of the filtering unit is grounded. The controller is connected to the switching unit and is used to execute the aforementioned low-light detection method.

[0012] In one embodiment, the maximum power point tracking circuit further includes a first current sampling unit disposed between the second end of the inductor energy storage unit and the first end of the switching unit, and a second current sampling unit is used to obtain a first current value flowing through the switching unit.

[0013] In one embodiment, the maximum power point tracking circuit further includes a second current sampling unit, which is disposed between the input terminal of the maximum power point tracking circuit and the first terminal of the inductor energy storage unit. The second current sampling unit is used to obtain a second current value flowing through the inductor energy storage unit.

[0014] In one embodiment, the maximum power tracking circuit further includes a voltage sampling unit connected to the input terminal and ground terminal of the maximum power tracking circuit, and the voltage sampling unit is used to acquire the input voltage of the maximum power tracking circuit.

[0015] A third aspect of this application provides a photovoltaic system, including a photovoltaic module and an energy storage device, wherein the energy storage device includes the aforementioned maximum power tracking circuit, and the maximum tracking circuit is connected to the photovoltaic module. Attached Figure Description

[0016] Figure 1 This is a schematic block diagram of the structure of an energy storage device equipped with a photovoltaic system, provided in an embodiment of this application.

[0017] Figure 2 This is a schematic flowchart of a low-light detection method provided in an embodiment of this application.

[0018] Figure 3 This is a flowchart illustrating the second weak light detection method provided in the embodiments of this application.

[0019] Figure 4 This is a flowchart illustrating the third weak light detection method provided in the embodiments of this application.

[0020] Figure 5 This is a flowchart illustrating the fourth low-light detection method provided in the embodiments of this application.

[0021] Figure 6 This is a flowchart illustrating the fifth low-light detection method provided in the embodiments of this application.

[0022] Figure 7 This is a structural block diagram of a maximum power tracking circuit provided in an embodiment of this application.

[0023] Figure 8 This is a structural block diagram of the second maximum power tracking circuit provided in the embodiments of this application.

[0024] Figure 9 This is a schematic diagram of the circuit structure of a photovoltaic system provided in an embodiment of this application. Detailed Implementation

[0025] It should be noted that the terms "first" and "second" in the specification, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0026] It should also be noted that the methods disclosed in the embodiments of this application or the methods shown in the flowcharts include one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchanged, and some steps can also be deleted.

[0027] Some embodiments will now be described with reference to the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0028] Outdoor energy storage devices are becoming increasingly popular among outdoor enthusiasts, especially those that combine clean energy with mobile energy storage. Integrating photovoltaic systems into outdoor energy storage devices is a recent hot research topic.

[0029] In related technologies, in order to maximize the utilization of the electrical energy output by photovoltaic panels, outdoor energy storage devices are equipped with a maximum power tracking circuit. This circuit tracks the maximum power of the electrical energy generated by the photovoltaic panels and outputs the electrical energy generated by the photovoltaic panels to the battery side of the outdoor energy storage device, thereby enabling the outdoor energy storage device to effectively store the electrical energy of the photovoltaic system.

[0030] However, in outdoor environments, it's impossible to guarantee that photovoltaic panels will always receive adequate sunlight. When exposed to strong sunlight, the maximum power tracking (MPT) circuit in the photovoltaic system will activate, while it may automatically shut down under weak sunlight. Therefore, in low-light outdoor conditions, the MPT circuit may cycle through activations, negatively impacting its performance.

[0031] In related technologies, to address the issue of maximum power point tracking (MPPT) circuits cyclically activating under low-light outdoor conditions, additional circuits, devices, or equipment are incorporated into the photovoltaic (PV) system to detect low-light irradiation of the PV panels. However, this implementation of additional circuits, devices, or equipment for detecting low-light irradiation in the PV system leads to a more complex circuit structure.

[0032] This application provides a low-light detection method to solve the problem of cyclic startup of the maximum power tracking circuit when a photovoltaic panel is illuminated by low light, while reducing the complexity of the circuit structure of the photovoltaic system.

[0033] Please refer to Figure 1 , Figure 1 This is a schematic block diagram of an energy storage device equipped with a photovoltaic panel, provided as an embodiment of this application. The energy storage device 100 includes a battery cell circuit 110, a DC / DC circuit 120, a maximum power tracking circuit 130, and an interface circuit 140 connected in sequence.

[0034] The interface circuit 140 is used for detachable connection of the photovoltaic panel 200, meaning the photovoltaic panel 200 can be detached from the energy storage device 100 and connected to the maximum power point tracking circuit 130 via the interface circuit 140. The photovoltaic panel 200 receives solar energy and converts it into DC power. The maximum power point tracking circuit 130 receives the DC power, tracks the maximum power point of the DC power, and then outputs the DC power to the DC / DC circuit 120. The DC / DC circuit 120 receives the DC power and adjusts the voltage of the DC power to the charging voltage of the battery cell circuit 110 to charge the battery cell circuit 110, thereby allowing the battery cell circuit 110 to store the DC power generated by the photovoltaic panel 200. The photovoltaic panel 200 and the energy storage device 100 constitute its photovoltaic system.

[0035] Next, combined Figure 1 This application introduces a low-light detection method. Please refer to [link / reference]. Figure 2 , Figure 2 This is a schematic flowchart of a low-light detection method provided in an embodiment of this application.

[0036] The low-light detection method is applied to a maximum power point tracking (MPPT) circuit, which includes an inductor energy storage unit and a switching unit. The first terminal of the inductor energy storage unit is connected to the input terminal of the MPPT circuit, and the second terminal of the inductor energy storage unit is connected to the output terminal of the MPPT circuit. The first terminal of the switching unit is connected to the second terminal of the inductor energy storage unit, and the second terminal of the switching unit is grounded. Specifically, the low-light detection method includes:

[0037] Step S21: Send a first control signal with a first preset frequency to the switching unit. The first control signal is used to control the switching unit to conduct at the first preset frequency so as to operate in the linear region.

[0038] In this embodiment, the switching unit includes, but is not limited to, a MOS (Metal-Oxide-Semiconductor Field-Effect Transistor). The first terminal of the switching unit can be the drain of the MOS, and the second terminal can be the source of the MOS. Furthermore, the maximum power point tracking circuit may include multiple MOS transistors; that is, a target MOS transistor can be selected as the aforementioned switching unit. The drain of the target MOS transistor is connected to the second terminal of the inductor energy storage unit, and the source of the target MOS transistor is grounded.

[0039] For example, when the maximum power tracking circuit 130 is a boost circuit, the MOSFET in the boost circuit is the target MOSFET.

[0040] The maximum power tracking circuit also includes a controller. The switching unit also includes a control terminal, which is the gate of the MOSFET when the switching unit is a MOSFET. The controller is connected to the control terminal of the switching unit and is used to send control signals to the switching unit.

[0041] The input terminal of the maximum power point tracking (MPPT) circuit is connected to the photovoltaic (PV) panel. When the PV panel is illuminated, it converts solar energy into DC power and inputs this DC power to the MPPT circuit via an interface circuit. When the MPPT circuit is in the off state, the controller, upon detecting the DC power input, sends a first control signal with a first preset frequency to the switching unit. This first control signal controls the switching unit to conduct at the first preset frequency, thus operating in the linear region. At this time, the MPPT circuit has not yet started tracking the maximum power point of the DC power supply. The switching unit operating in the linear region exhibits a DC voltage characteristic between its first and second terminals, allowing the effective DC current value input from the PV panel to the switching unit to be obtained from either the first or second terminal.

[0042] For example, when the switching unit is a MOSFET, the MOSFET conducts its drain and source terminals after receiving a first control signal of a first preset frequency through its gate, and operates in the linear region. At this time, the DC power supply of the photovoltaic panel flows through the inductive energy storage unit, the drain and source of the MOSFET, and then to ground, forming a loop. The MOSFET operating in the linear region exhibits DC voltage characteristics.

[0043] The first control signal can be a PWM signal (Pulse Width Modulation). To ensure the switching unit operates in the linear region, the first preset frequency needs to be at the megahertz level. This first control signal can then flow through the first terminal of the switching unit to the inductor energy storage unit, serving as the excitation source signal for the inductor energy storage unit. Since the first preset frequency is at the megahertz level, the first control signal, acting as the excitation source signal, allows the inductor energy storage unit to exhibit low impedance, approximating a wire. This enables unimpeded transmission of the DC power from the photovoltaic panel to the switching unit, further ensuring that the DC current value obtained from the switching unit is the same as the DC current value of the photovoltaic panel.

[0044] Step S22: Obtain the first current value flowing through the switching unit.

[0045] In this embodiment, the first current value is the DC current value input from the photovoltaic panel to the switching unit. Since the switching unit operates in the linear region at this time, making its two ends exhibit DC voltage characteristics, and the inductive energy storage unit presents low impedance and approximates a wire, the effective DC current value of the photovoltaic panel can be detected from the first or second end of the switching unit, which is the aforementioned first current value.

[0046] The switching unit includes a current sampling unit at one of its first and / or second terminals. The sampling unit acquires a first current value flowing through the switching unit from the first terminal, or vice versa. Alternatively, it can simultaneously acquire the current values ​​from both terminals and then average them using an algorithm to obtain a more reliable first current value. Furthermore, the current sampling unit is connected to a controller to transmit the first current value to the controller.

[0047] Step S23: If the first current value is greater than or equal to the preset current threshold, a start signal is output to the maximum power tracking circuit. The start signal is used to control the maximum power tracking circuit to perform maximum power tracking.

[0048] In this embodiment, the aforementioned preset current threshold is the critical value for determining whether the photovoltaic panel is under weak light irradiation. When the first current value flowing through the switching unit is greater than or equal to the preset current threshold, it is determined that the photovoltaic panel is not under weak light irradiation. Conversely, when the first current value flowing through the switching unit is less than the preset current threshold, it is determined that the photovoltaic panel is under weak light irradiation.

[0049] The preset current threshold can be obtained through experimentation. For example, an adjustable DC power supply can be used to simulate the input of a photovoltaic panel to the maximum power point tracking circuit to find the current value of the DC power supply that can just start the maximum power point tracking circuit. By adding a preset value to this current value, the aforementioned preset current threshold can be obtained.

[0050] When the controller determines that the first current value is greater than or equal to a preset current threshold, it can output a start signal to the maximum power point tracking (MPPT) circuit. Specifically, it can output the start signal to all control elements of the MPPT circuit to control the MPPT circuit to perform maximum power point tracking of the DC power input to the photovoltaic panel. These control elements include the aforementioned switching unit, and the frequency of the start signal is different from the first preset frequency.

[0051] It is understandable that before controlling the maximum power point tracking (MPPT) circuit to perform MPPT, a first control signal with a first preset frequency is sent to the switching unit to turn it on and operate in the linear region. This causes the first and second terminals of the switching unit to exhibit DC voltage characteristics, allowing the effective first current value of the photovoltaic input to the switching unit to be obtained from either the first or second terminal. After determining that the first current value is greater than or equal to a preset current threshold, the MPPT circuit is then controlled to perform MPPT via a start signal, effectively preventing the cyclic start-up of the MPPT circuit. Furthermore, the aforementioned low-light detection process is achieved by controlling the existing switching unit of the MPPT circuit to operate in the linear region, eliminating the need for additional detection circuits, detection devices, or detection equipment, thereby reducing the complexity of the photovoltaic system's circuit structure.

[0052] In some embodiments, the output voltage value of the photovoltaic panel's output port can also be obtained. Only when this output voltage value is greater than or equal to the power-on voltage of the maximum power point tracking (MPPT) circuit is a first control signal with a first preset frequency sent to the switching unit, and subsequent steps are executed. That is, after detecting that the photovoltaic panel's output voltage has reached the power-on voltage, the MPPT circuit starts, then first sends the aforementioned first control signal to the switching unit and executes the first current value detection step. When the detected first current value is greater than or equal to a preset current threshold, the MPPT circuit then tracks the photovoltaic panel's maximum power point.

[0053] Please refer to Figure 3 , Figure 3 This is a schematic flowchart illustrating another low-light detection method provided in an embodiment of this application. Wherein, Figure 3 The low-light detection method shown includes steps S31-S34. Figure 3 Steps S31-S33 shown are Figure 2 The steps S21-S23 shown are the same, and will not be repeated here. Figure 3 The low-light detection method shown is similar to Figure 2 The low-light detection method shown differs in that it also includes:

[0054] Step S34: If the first current value is less than the preset current threshold, a low light warning signal is output. The low light warning signal is used to remind the user that the current situation is under low light conditions.

[0055] In this embodiment, when the controller determines that the first current value is less than a preset current threshold, it determines that the photovoltaic panel is under weak light illumination. The controller then outputs a weak light warning signal to alert the user that the current condition is under weak light, thereby improving the user experience. Specifically, in the aforementioned energy storage device equipped with a photovoltaic system, the display screen can receive the weak light warning signal and output a corresponding image to alert the user, or a voice module can output a voice prompt; this is not limited to this embodiment.

[0056] Please refer to Figure 4 , Figure 4 This is a schematic flowchart illustrating another low-light detection method provided in an embodiment of this application. Wherein, Figure 4 The low-light detection method shown includes steps S41-S45. Figure 4 The steps S41-S42 shown are... Figure 2 The steps S21-S22 shown are the same, and will not be repeated here. Figure 4 The low-light detection method shown is similar to Figure 2 The low-light detection method shown differs in that it includes:

[0057] Step S43: Obtain the input voltage of the maximum power tracking circuit.

[0058] Step S44: Calculate the input power of the maximum power tracking circuit based on the input voltage and the first current value.

[0059] In this embodiment of the invention, since the switching unit itself has internal resistance, it can consume the electrical energy input to the maximum power tracking circuit, i.e., consume the electrical energy input to the photovoltaic panel. Therefore, it is further possible to determine whether the photovoltaic panel is under weak light irradiation by detecting the power consumed by the switching unit.

[0060] The power consumed by the switching unit when operating in the linear region is equal to the input power from the photovoltaic panel to the maximum power point tracking circuit. After obtaining the input voltage, the power consumed by the switching unit, i.e., the input power from the photovoltaic panel to the maximum power point tracking circuit, can be calculated by combining the first current value.

[0061] In this embodiment, a voltage sampling unit can be provided at the input terminal of the maximum power point tracking circuit to obtain the input voltage from the photovoltaic panel to the maximum power point tracking circuit. Furthermore, this voltage sampling unit is connected to a controller to transmit the collected input voltage value.

[0062] Step S45: If the input power is greater than or equal to the preset power threshold, then output a start signal to the maximum power tracking circuit.

[0063] In this embodiment, the aforementioned preset power threshold is the critical power value for determining whether the photovoltaic panel is under weak light irradiation. When the input power of the photovoltaic panel is greater than or equal to the preset power threshold, it is determined that the photovoltaic panel is not under weak light irradiation. Conversely, when the input power of the photovoltaic panel is less than the preset power threshold, it is determined that the photovoltaic panel is under weak light irradiation. It can be understood that by obtaining the input voltage of the maximum power point tracking circuit and further combining it with the first current value, the power consumed by the switching unit can be calculated, i.e., the input power of the photovoltaic panel can be calculated. Using the input power, the weak light irradiation state of the photovoltaic panel can be determined more accurately, thereby more effectively preventing the maximum power point tracking circuit from cyclically starting.

[0064] The preset power threshold can also be obtained through experimentation. For example, an adjustable DC power supply can be used to simulate the input of a photovoltaic panel to the maximum power tracking circuit to find the power value of the DC power supply that can just start the maximum power tracking circuit. By adding a preset power value to this power value, the aforementioned preset power threshold can be obtained.

[0065] Please refer to Figure 5 , Figure 5 A flowchart illustrating another low-light detection method provided in this application embodiment, specifically including the following steps:

[0066] Step S51: When the first control signal is not sent, a second control signal with a second preset frequency is sent to the switching unit so that the switching unit operates in the saturation region, and the second preset frequency is less than the first preset frequency.

[0067] In this embodiment, when the maximum power point tracking circuit is in the off state, after the controller detects a DC power input to the maximum power point tracking circuit, in addition to sending the first control signal described in the above embodiment, the controller can also send a second control signal with a second preset frequency to the switching unit. That is, the controller can choose to send either the first control signal or the second control signal.

[0068] The second control signal has a second preset frequency, which is in the kilohertz range, thus serving as the excitation source signal for the inductive energy storage device. This causes the inductive energy storage unit to exhibit impedance characteristics and possess a certain impedance value. The switching unit receiving the second control signal operates in the saturation region, at which point the maximum power point tracking circuit has not yet performed maximum power point tracking on the DC power supply. The switching unit operating in the saturation region exhibits switching characteristics between its first and second terminals, meaning that the first and second terminals of the switching unit switch between connection and disconnection according to the second preset frequency.

[0069] The second control signal can be a PWM signal. To enable the switching unit to operate in the saturation region, the second preset frequency needs to be at the kilohertz level, while the first preset frequency is at the megahertz level. Therefore, the second preset frequency is lower than the first preset frequency.

[0070] Step S52: Obtain the second current value flowing through the inductor energy storage unit.

[0071] In this embodiment, the second control signal can flow to the inductor energy storage unit through the first terminal of the switching unit, serving as the excitation source signal for the inductor energy storage unit. Since the second preset frequency is in the kilohertz range, the second control signal, as the excitation source signal, can make the inductor energy storage unit exhibit impedance characteristics and possess a certain impedance value. Furthermore, since the inductor energy storage unit is connected to the input terminal of the maximum power point tracking circuit through its first terminal, and given the characteristic that only direct current flows through the inductor energy storage unit due to its impedance characteristics, an effective direct current value input from the photovoltaic panel to the inductor energy storage unit can be obtained. This direct current value is the aforementioned second current value.

[0072] A current sampling unit may be provided at the first end of the inductor energy storage unit. The current sampling unit obtains a second current value flowing through the inductor energy storage unit from the first end. Furthermore, the current sampling unit is connected to the controller to transmit the second current value to the controller.

[0073] Step S53: If the second current value is greater than or equal to the preset current threshold, a start signal is output to the maximum power tracking circuit. The start signal is used to control the maximum power tracking circuit to perform maximum power tracking.

[0074] In this embodiment, step S53 is similar to step S23 described above. Please refer to the relevant content of step S23 in the previous embodiment, and it will not be repeated here.

[0075] Please refer to Figure 6 , Figure 6 This is a schematic flowchart illustrating another low-light detection method provided in an embodiment of this application. Wherein, Figure 6 The low-light detection method shown includes steps S61-S65. Figure 4 Steps S61-S62 shown are Figure 2 The steps S51-S52 shown are the same, and will not be repeated here. Figure 6 The low-light detection method shown is similar to Figure 5 The low-light detection method shown differs in that it includes:

[0076] Step S63: Obtain the input voltage of the maximum power tracking circuit.

[0077] Step S64: Calculate the input power of the maximum power tracking circuit based on the input voltage and the second current value.

[0078] In this embodiment, since the aforementioned inductive energy storage unit exhibits impedance characteristics and has a certain impedance value, the impedance of the inductive energy storage unit can dissipate the electrical energy input to the maximum power point tracking circuit, i.e., the electrical energy input to the photovoltaic panel. Therefore, it is further possible to determine whether the photovoltaic panel is under weak light irradiation by detecting the power consumed by the inductive energy storage unit.

[0079] The power consumed by the inductive energy storage unit, exhibiting impedance characteristics, is equal to the input power from the photovoltaic panel to the maximum power point tracking circuit. After obtaining the input voltage, the power consumed by the inductive energy storage unit, i.e., the input power from the photovoltaic panel to the maximum power point tracking circuit, can be calculated by combining it with the second current value.

[0080] Step S65: If the input power is greater than or equal to the preset power threshold, then output a start signal to the maximum power tracking circuit.

[0081] In this embodiment, step S65 is similar to step S45 described above, and the relevant content of step S45 in the previous embodiment can be referred to, and will not be repeated here. It is understood that by obtaining the input voltage of the maximum power point tracking circuit and further combining it with the second current value, the power consumed by the current inductor energy storage unit can be calculated, i.e., the current input power of the photovoltaic panel. This input power allows for a more accurate determination of the photovoltaic panel's weak light irradiation state, thereby more effectively preventing the maximum power point tracking circuit from cyclically starting.

[0082] Please refer to Figure 7 , Figure 7 This is a structural block diagram of a maximum power point tracking (MPPT) circuit provided in an embodiment of this application. The MPPT circuit 700 includes: an inductor energy storage unit 710, a switching unit 720, a filtering unit 730, and a controller 740.

[0083] In this embodiment, the first end of the inductor energy storage unit 710 is connected to the input end of the maximum power point tracking circuit 700, the second end of the inductor energy storage unit 710 is connected to the output end of the maximum power point tracking circuit 700, the first end of the switching unit 720 is connected to the second end of the inductor energy storage unit 710, the second end of the switching unit 720 is grounded, the controller 740 is connected to the switching unit 720, the first end of the filtering unit 730 is connected to the input end of the maximum power point tracking circuit 700, and the second end of the filtering unit 730 is grounded.

[0084] The controller 740 is used to execute the low-light detection method shown in any of the above embodiments. It is understood that the beneficial effects achieved by the maximum power tracking circuit provided in this application embodiment can be referred to in conjunction with the beneficial effects of the corresponding low-light detection methods provided above, and will not be repeated here.

[0085] Please refer to Figure 8 This is a structural block diagram of the second maximum power tracking circuit provided in an embodiment of this application. Figure 8 The maximum power tracking circuit 700 shown is... Figure 7 The maximum power tracking circuit 700 shown differs in that... Figure 8 The maximum power tracking circuit 700 shown also includes:

[0086] A first current sampling unit 750 is disposed between the second end of the inductor energy storage unit 710 and the first end of the switching unit 720. The first current sampling unit 750 is used to obtain a first current value flowing through the switching unit.

[0087] The second current sampling unit 760 is disposed between the input terminal of the maximum power tracking circuit 700 and the first terminal of the inductor energy storage unit 710. The second current sampling unit is used to obtain the second current value flowing through the inductor energy storage unit 710.

[0088] A voltage sampling unit 770 is connected to the input terminal and the ground terminal of the maximum power point tracking circuit 700. The voltage sampling unit 770 is used to obtain the input voltage of the maximum power point tracking circuit.

[0089] The first current sampling unit 750, the second current sampling unit 760, and the voltage sampling unit 770 each include a control terminal, which is connected to the controller 740. The controller 740 is used to execute the weak light detection method shown in any of the above embodiments. Similarly, the beneficial effects achieved by the maximum power tracking circuit provided in this application embodiment can be referred to the beneficial effects of the corresponding weak light detection method provided above, and will not be repeated here.

[0090] Please refer to Figure 9 , Figure 9 This is a schematic diagram of the circuit structure of a photovoltaic system provided in an embodiment of this application. The photovoltaic system 900 includes a photovoltaic module 910 and an energy storage device 920. The energy storage device 920 includes a maximum power point tracking (MPPT) circuit 921. The MPPT circuit 921 is connected to the photovoltaic module 910.

[0091] In this embodiment, the photovoltaic module 910 includes a photovoltaic panel PV. The maximum power tracking circuit 921 includes capacitors C1 and C2, resistors R1 and R2, and a filter capacitor C. bst Inductor L bst Switch S bst and diode D bst .

[0092] Among them, the filter capacitor C bst The first terminal is connected to the first terminal of the photovoltaic panel PV, and the filter capacitor C bst The second terminal of the inductor L is connected to the second terminal of the photovoltaic panel PV and grounded. bst The first end is connected to the first end of the photovoltaic panel PV, and the inductor L bst The second end is connected to the switching transistor S. bst The drain (D) of the transistor. The switching transistor S... bst The gate (G) of the transistor is used to receive control signals from the controller, and the switching transistor S... bst The source (S) of diode D is grounded. bst The positive terminal is connected to the inductor L bst The second terminal, diode D bstThe negative terminal of capacitor C1 is connected to the first terminal of capacitor C1. The second terminal of capacitor C1 is connected to the first terminal of capacitor C2, and the second terminal of capacitor C2 is grounded. The first terminal of resistor R1 is connected to the first terminal of capacitor C1, and the second terminal of resistor R1 is connected to the second terminal of capacitor C1. The first terminal of resistor R2 is connected to the first terminal of capacitor C2, and the second terminal of resistor R2 is connected to the second terminal of capacitor C2.

[0093] In this embodiment of the application, when the photovoltaic panel PV inputs DC power to the maximum power tracking circuit 921, the controller sends a first control signal with a first preset frequency to the switching transistor S. bst To make the switching transistor S bst Operating in the linear region, thus enabling the switching transistor S bst The drain and source terminals exhibit DC voltage characteristics, and the drain and source terminals have a current I. DS This refers to the input current of the photovoltaic panel (PV). By determining the current I... DS If the current is greater than or equal to a preset current threshold, it can be determined that the photovoltaic panel (PV) is not under weak light illumination, and the maximum power point tracking circuit 921 can be controlled to perform maximum power point tracking on the DC power input to the photovoltaic panel (PV). Alternatively, the switching transistor S can be further detected. bst The voltage V across the drain and source terminals DS Calculate the power consumed P = I DS ×V DS , which is the input power of the photovoltaic panel PV. By determining that the input power P is greater than or equal to the preset power threshold, it can be determined that the photovoltaic panel PV is not under weak light irradiation. Then, the maximum power point tracking circuit 921 can be controlled to perform maximum power point tracking on the DC power input to the photovoltaic panel PV.

[0094] Alternatively, when the PV inputs DC power to the maximum power tracking circuit 921, if the controller does not send the aforementioned first control signal, the controller also sends a second control signal with a second preset frequency to the switching transistor S. bst To make the switching transistor S bst Operating in the saturation region, thus enabling the switching transistor S bst The drain and source terminals of the inductor L exhibit switching characteristics. bst The frequency of the excitation source is the second preset frequency, which makes the inductor L bst It exhibits impedance characteristics, and the inductance L bst The impedance is Z = 2 × π × f × L, where f is the second preset frequency and L is the inductance value. Since the inductance L... bst By connecting the first terminal in series with the photovoltaic panel PV, the inductor L can be used to... bst The first terminal obtains the current value I input from the photovoltaic panel (PV). L By determining I LIf the current is greater than or equal to a preset current threshold, it can be determined that the photovoltaic panel (PV) is not under weak light illumination, and the maximum power point tracking circuit 921 can be controlled to perform maximum power point tracking on the DC power input to the PV panel. Alternatively, the input voltage V between the input terminal and the ground terminal of the maximum power point tracking circuit 921 can be further detected. PV Calculate the input power P = I of the photovoltaic panel PV. L ×V PV By determining that the input power P is greater than or equal to the preset power threshold, it can be determined that the photovoltaic panel PV is not under weak light irradiation, and the maximum power point tracking circuit 921 can be controlled to perform maximum power point tracking on the DC power input to the photovoltaic panel PV.

[0095] It is understood that the beneficial effects of the photovoltaic system provided in this application embodiment can be referred to the beneficial effects of the corresponding weak light detection method provided above, and will not be repeated here.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the spirit and scope of the technical solutions of this application.

Claims

1. A weak light detection method, applied to a maximum power tracking circuit, characterized in that, The maximum power point tracking (MPPT) circuit includes an inductive energy storage unit and a switching unit. A first terminal of the inductive energy storage unit is connected to the input terminal of the MPPT circuit, and a second terminal of the inductive energy storage unit is connected to the output terminal of the MPPT circuit. A first terminal of the switching unit is connected to the second terminal of the inductive energy storage unit, and the second terminal of the switching unit is grounded. The method includes: After detecting that a DC power supply is input to the maximum power tracking circuit, a first control signal with a first preset frequency is sent to the switching unit. The first control signal is used to control the switching unit to conduct at the first preset frequency so as to operate in the linear region. Obtain the first current value flowing through the switching unit; If the first current value is greater than or equal to a preset current threshold, a start signal is output to the maximum power tracking circuit. The start signal is used to control the maximum power tracking circuit to perform maximum power tracking. The frequency of the start signal is different from the first preset frequency.

2. The weak light detection method according to claim 1, characterized in that, The method further includes: If the first current value is less than the preset current threshold, a low light warning signal is output, which is used to remind the user that the user is currently in a low light condition.

3. The weak light detection method according to claim 1, characterized in that, The method further includes: Obtain the input voltage of the maximum power tracking circuit; The input power of the maximum power tracking circuit is calculated based on the input voltage and the first current value. If the input power is greater than or equal to a preset power threshold, the start signal is output to the maximum power tracking circuit.

4. The weak light detection method according to claim 1, characterized in that, The method further includes: When the first control signal is not sent, a second control signal with a second preset frequency is sent to the switching unit so that the switching unit operates in the saturation region, wherein the second preset frequency is less than the first preset frequency. Obtain the second current value flowing through the inductive energy storage unit; If the second current value is greater than or equal to the preset current threshold, a start signal is output to the maximum power tracking circuit, and the start signal is used to control the maximum power tracking circuit to perform maximum power tracking.

5. The weak light detection method according to claim 4, characterized in that, The method further includes: Obtain the input voltage of the maximum power tracking circuit; The input power of the maximum power tracking circuit is calculated based on the input voltage and the second current value. If the input power is greater than or equal to a preset power threshold, the start signal is output to the maximum power tracking circuit.

6. A maximum power tracking circuit, characterized in that, The device includes an inductive energy storage unit, a switching unit, a filtering unit, and a controller. A first terminal of the inductive energy storage unit is connected to the input terminal of the maximum power point tracking (MPPT) circuit, and a second terminal of the inductive energy storage unit is connected to the output terminal of the MPPT circuit. A first terminal of the switching unit is connected to the second terminal of the inductive energy storage unit, and the second terminal of the switching unit is grounded. A first terminal of the filtering unit is connected to the input terminal of the MPPT circuit, and the second terminal of the filtering unit is grounded. The controller is connected to the switching unit, and the controller is used to execute the weak light detection method as described in any one of claims 1-5.

7. The maximum power tracking circuit according to claim 6, characterized in that, Also includes: A first current sampling unit is disposed between the second end of the inductor energy storage unit and the first end of the switching unit. The first current sampling unit is used to obtain a first current value flowing through the switching unit.

8. The maximum power tracking circuit according to claim 6, characterized in that, Also includes: The second current sampling unit is disposed between the input terminal of the maximum power point tracking circuit and the first terminal of the inductor energy storage unit. The second current sampling unit is used to obtain the second current value flowing through the inductor energy storage unit.

9. The maximum power point tracking circuit according to claim 6, characterized in that, Also includes: A voltage sampling unit is connected to the input terminal and the ground terminal of the maximum power point tracking circuit, and the voltage sampling unit is used to obtain the input voltage of the maximum power point tracking circuit.

10. A photovoltaic system comprising a photovoltaic module and an energy storage device, the energy storage device comprising a maximum power point tracking circuit as described in any one of claims 6-9; the maximum power point tracking circuit being connected to the photovoltaic module.

Images