Power converter, maximum power point tracking method, controller and power supply system

Abstract

The application provides a power converter, a maximum power point tracking method, a controller and a power supply system, which are applied to the technical field of power conversion and relate to a power converter including a control module and a power conversion circuit connected with a photovoltaic module. The control module obtains electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling moments, determines a target parameter change rate according to the obtained electrical parameters of the at least two maximum power points, and determines the shading condition of the photovoltaic module connected with the power conversion circuit based on the size relationship between the target parameter change rate and a preset parameter change range, thereby solving the problem that related technologies cannot identify whether the photovoltaic module is shaded, providing a reference basis for power converter operation control, and reducing power generation loss caused by shading.

Description

Technical Field

[0001] This application relates to the field of power converter technology, specifically to a power converter, a maximum power point tracking method, a controller, and a power supply system. Background Technology

[0002] In photovoltaic (PV) power generation systems, MPPT (Maximum Power Point Tracking) technology is typically used to ensure that PV modules always operate near their maximum power point in order to maximize power generation efficiency. However, when PV modules experience partial shading due to factors such as building shadows, vegetation, snow accumulation, or inter-array shading, their PV (power-voltage) characteristic curve changes from a single peak (i.e., only one maximum power point exists) to a multi-peak curve (i.e., multiple local maximum power points exist).

[0003] The MPPT control method provided by related technologies makes control decisions based only on local information near the current operating point, and cannot promptly identify whether photovoltaic modules are shaded. Therefore, how to identify whether photovoltaic modules are shaded, provide a reference for the operation control of the power converter, and reduce power generation losses caused by shading has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, this application aims to provide a power converter, a maximum power point tracking method, a controller, and a power supply system to solve the problem that related technologies cannot identify whether photovoltaic modules are shaded, making it difficult to provide a reference for the operation and control of the power converter, resulting in power generation loss due to shading.

[0005] In a first aspect, this application provides a power converter, comprising: A power conversion circuit, wherein the input side of the power conversion circuit is connected to the photovoltaic module; The control module is connected to the control terminal of the power conversion circuit; The control module is configured as follows: Obtain the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times; The target parameter change rate is determined based on the electrical parameters of the at least two maximum power points; Based on the relationship between the rate of change of the target parameter and the range of change of the preset parameter, the shading status of the photovoltaic module connected to the power conversion circuit is determined. The range of variation of the preset parameters is determined based on the actual shading of the photovoltaic module and the historical operating data of the power conversion circuit.

[0006] In one optional implementation, the preset parameter variation range includes a first preset parameter variation range, which is determined based on historical operating data of the power conversion circuit under unshaded conditions of the photovoltaic module; The control module is specifically configured as follows: If the rate of change of the target parameter is within the range of the first preset parameter, it is determined that the photovoltaic module connected to the power conversion circuit is not shaded and corresponds to a maximum power point. If the rate of change of the target parameter is not within the range of the first preset parameter, it is determined that the photovoltaic module connected to the power conversion circuit is shaded.

[0007] In an optional implementation, the preset parameter variation range further includes a second preset parameter variation range and at least one third preset parameter variation range. The second preset parameter variation range and the third preset parameter variation range are determined based on the historical operating data of the power conversion circuit when the photovoltaic module is shaded. The upper limit and lower limit of the second preset parameter variation range are both negative. The control module is specifically configured as follows: If the rate of change of the target parameter is within the range of the second preset parameter, it is determined that the photovoltaic module connected to the power conversion circuit is in a transition state. The transition state refers to the photovoltaic module being shaded and corresponding to a maximum power point. If the rate of change of the target parameter is within the range of any of the third preset parameters, it is determined that the photovoltaic module connected to the power conversion circuit is shaded and corresponds to at least two local maximum power points.

[0008] In one optional implementation, the electrical parameters of the at least two maximum power points include the electrical parameters of three or more maximum power points; The control module is also configured to: Calculate the rate of change of electrical parameters for any two adjacent maximum power points to obtain multiple rate of change of parameters. The change in the shading area of ​​the photovoltaic module is determined based on the time-series trend of the change rate of each parameter.

[0009] In one optional implementation, the control module is specifically configured as follows: If the rate of change of each parameter increases sequentially in chronological order, it is determined that the shading area of ​​the photovoltaic module gradually decreases. If the rate of change of each parameter decreases sequentially in chronological order, it is determined that the shading area of ​​the photovoltaic module gradually increases.

[0010] In an optional implementation, where the photovoltaic module connected to the power conversion circuit corresponds to at least two local maximum power points, the control module is further configured to: The power conversion circuit is driven to adjust the output power of the photovoltaic module until the power conversion circuit operates at the global maximum power point, where the power value of the global maximum power point is greater than the power value of any other local maximum power point.

[0011] In one optional implementation, the control module is specifically configured as follows: The power conversion circuit is driven to reduce the output voltage of the photovoltaic module until it reaches a preset base voltage. The local power point with the largest power value during the reduction of the output voltage of the photovoltaic module is determined as the global maximum power point. The preset base voltage is the minimum voltage that meets the operating requirements of the power conversion circuit.

[0012] In one optional implementation, the electrical parameters of the at least two maximum power points include a first power value and a first voltage value corresponding to the first maximum power point, and a second power value and a second voltage value corresponding to the second maximum power point. The control module is specifically configured as follows: The difference between the first power value and the second power value is determined as the target power deviation; The difference between the first voltage value and the second voltage value is determined as the first voltage deviation; The ratio of the target power deviation to the first voltage deviation is determined as the rate of change of the target parameter.

[0013] In one optional implementation, the electrical parameters of the at least two maximum power points include a first current value and a first voltage value corresponding to the first maximum power point, and a second current value and a second voltage value corresponding to the second maximum power point. The control module is specifically configured as follows: The difference between the first current value and the second current value is determined as the target current deviation; The difference between the first voltage value and the second voltage value is determined as the second voltage deviation; The ratio of the target current deviation to the second voltage deviation is determined as the rate of change of the target parameter.

[0014] In an optional implementation, the control module is further configured to: The actual shading status of the photovoltaic module and the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times are obtained. The reference curves are fitted based on the electrical parameters corresponding to each of the maximum power points, and the reference curves include the curves of each of the maximum power points changing with voltage, or the curves of each of the maximum power points changing with current. Determine the slope of the reference curve; The range of preset parameter variations corresponding to the actual occlusion situation is determined based on the slope of the reference curve.

[0015] Secondly, this application provides a maximum power point tracking method applied to a power converter, the power converter including a power conversion circuit, and the input terminal of the power conversion circuit connected to a photovoltaic module, the method comprising: Obtain the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times; The target parameter change rate is determined based on the electrical parameters of the at least two maximum power points; Based on the relationship between the rate of change of the target parameter and the range of change of the preset parameter, the shading status of the photovoltaic module connected to the power conversion circuit is determined. The range of variation of the preset parameters is determined based on the actual shading of the photovoltaic module and the historical operating data of the power conversion circuit.

[0016] In one optional implementation, the preset parameter variation range includes a first preset parameter variation range, which is determined based on historical operating data of the power conversion circuit under unshaded conditions of the photovoltaic module; The step of determining the shading status of the photovoltaic modules connected to the power conversion circuit based on the relationship between the target parameter change rate and the preset parameter change range includes: If the rate of change of the target parameter is within the range of the first preset parameter, it is determined that the photovoltaic module connected to the power conversion circuit is not shaded and corresponds to a maximum power point. If the rate of change of the target parameter is not within the range of the first preset parameter, it is determined that the photovoltaic module connected to the power conversion circuit is shaded.

[0017] In an optional implementation, the preset parameter variation range further includes a second preset parameter variation range and at least one third preset parameter variation range. The second preset parameter variation range and the third preset parameter variation range are determined based on historical operating data of the power conversion circuit under shading conditions of the photovoltaic module, and the upper and lower limits of the second preset parameter variation range are both negative values. The method further includes: If the rate of change of the target parameter is within the range of the second preset parameter, it is determined that the photovoltaic module connected to the power conversion circuit is in a transition state. The transition state refers to the photovoltaic module being shaded and corresponding to a maximum power point. If the rate of change of the target parameter is within the range of any of the third preset parameters, it is determined that the photovoltaic module connected to the power conversion circuit is shaded and corresponds to at least two local maximum power points.

[0018] In one optional implementation, the electrical parameters of the at least two maximum power points include electrical parameters of three or more maximum power points, and the method further includes: Calculate the rate of change of electrical parameters for any two adjacent maximum power points to obtain multiple rate of change of parameters. If the rate of change of each parameter increases sequentially in chronological order, it is determined that the shading area of ​​the photovoltaic module gradually decreases. If the rate of change of each parameter decreases sequentially in chronological order, it is determined that the shading area of ​​the photovoltaic module gradually increases.

[0019] In an optional embodiment, when the photovoltaic module connected to the power conversion circuit corresponds to at least two local maximum power points, the method further includes: The power conversion circuit is driven to adjust the output power of the photovoltaic module until the power conversion circuit operates at the global maximum power point, where the power value of the global maximum power point is greater than the power value of any other local maximum power point.

[0020] In an optional implementation, the method further includes: The actual shading status of the photovoltaic module and the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times are obtained. The reference curves are fitted based on the electrical parameters corresponding to each of the maximum power points, and the reference curves include the curves of each of the maximum power points changing with voltage, or the curves of each of the maximum power points changing with current. Determine the slope of the reference curve; The range of preset parameter variations corresponding to the actual occlusion situation is determined based on the slope of the reference curve.

[0021] Thirdly, this application provides a controller including a memory, a processor, and a computer program stored in the memory and executed by the processor, wherein the processor executes the computer program to implement the steps of the maximum power point tracking method as described in any embodiment of the second aspect of this application.

[0022] Fourthly, this application provides a power supply system, including a power converter as described in any embodiment of the first aspect of this application.

[0023] Based on the above, the power converter provided in this application includes a control module and a power conversion circuit connected to a photovoltaic module. The control module acquires the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times, determines the target parameter change rate based on the electrical parameters of the at least two maximum power points, and determines the shading status of the photovoltaic module connected to the power conversion circuit based on the relationship between the target parameter change rate and the preset parameter change range. This solves the problem that related technologies cannot identify whether the photovoltaic module is shading, and can provide a reference for the operation control of the power converter, reducing power generation losses caused by shading. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 It is the PV curve of the power conversion circuit in related technologies.

[0026] Figure 2 This is a structural block diagram of the power converter provided in the embodiments of this application.

[0027] Figure 3a This is the PV curve of the first power conversion circuit.

[0028] Figure 3b This is the PV curve diagram of the second type of power conversion circuit.

[0029] Figure 4a This is the PV curve of the third type of power conversion circuit.

[0030] Figure 4b This is the PV curve diagram of the fourth type of power conversion circuit.

[0031] Figure 5 This is the PV curve of the fifth type of power conversion circuit.

[0032] Figure 6 This is a flowchart of a maximum power tracking method provided in an embodiment of this application.

[0033] Figure 7 This is a structural block diagram of a controller provided in an embodiment of this application. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] As mentioned earlier, to maximize power generation efficiency, photovoltaic (PV) systems typically employ MPPT (Maximum Power Point Test) technology to ensure that PV modules always operate near their maximum power point. However, in actual operation, PV systems are susceptible to various types of shading, including shading from fixed objects, shading from natural environmental factors, and shading between PV arrays. Fixed objects include buildings, PV module supports, and other PV equipment. Natural environmental factors include shading caused by the growth of trees or climbing plants around the PV modules over time, and shading caused by snow cover. PV modules exhibit different PV (Power-Voltage) characteristic curves depending on whether they are unshaded or shaded. (See [link to relevant documentation]). Figure 1 As shown, when the photovoltaic module is not shaded, its PV curve S1 has a single-peak characteristic, that is, there is only one maximum power point A. However, when the photovoltaic module is shaded, the PV curve S2 of the photovoltaic module has a multi-peak characteristic, that is, there are multiple local maximum power points, namely local maximum power points B, C and D in the figure.

[0036] The MPPT control methods provided by related technologies make control decisions based solely on local information near the current operating point, such as the perturbation-observation method or the three-point method. Their basic working principle is a step-by-step search based on local power information near the current operating point. Essentially, it is a closed-loop control guided by static characteristics at a single moment, and cannot promptly identify whether photovoltaic modules are shading. Therefore, how to identify whether photovoltaic modules are shading, provide a reference for the operation and control of the power converter, and reduce power generation losses caused by shading has become a technical problem that urgently needs to be solved by those skilled in the art.

[0037] To address the aforementioned problems, embodiments of this application provide a power converter, see below. Figure 2 As shown, the power converter provided in this embodiment includes a power conversion circuit and a control module.

[0038] The input side of the power conversion circuit is connected to the photovoltaic (PV) module. It converts the direct current generated by the PV module into electrical power, adjusting the output voltage and current of the PV module, thereby changing the output power. It should be noted that the number of PV modules can be configured according to the actual power supply system conditions in practical applications. Figure 2The example uses n photovoltaic modules, where n ≥ 1. The power conversion circuit can be a DC (Direct Current) / DC (Direct Current) converter or a DC / AC (Alternating Current) converter. In some scenarios, the power conversion circuit can also include a series-connected DC / DC converter and a DC / AC converter. In practical applications, the specific form of the power conversion circuit can be selected based on the power supply system design requirements. This application does not impose any specific limitations on this.

[0039] The control module is connected to the control terminal of the power conversion circuit and can control the operation of the power conversion circuit. In practical applications, the control module may include processing chips such as microcontrollers, digital signal processors or field programmable gate arrays, as well as supporting sampling circuits, driving circuits, etc.

[0040] As an optional implementation, the power converter can also include at least two power conversion circuits. The control module is connected to the control terminal of each power conversion circuit, and the control process of each power conversion circuit is independent and does not affect the others. The control module independently executes the control logic described later in this application for each power conversion circuit to suit the actual situation of different photovoltaic modules and maximize the utilization of the electrical power of the photovoltaic modules connected to each power conversion circuit. Based on this, as an optional implementation, each power conversion circuit can be configured with an independent control module to achieve one-to-one control of the power conversion circuits by the control module. In another optional implementation, an independent control unit can be set in the control module, with each control unit corresponding to one power conversion circuit. Each control unit controls the operation of its corresponding power conversion circuit by executing the control logic described later in this embodiment. Since the control logic of each power conversion circuit is the same and performed independently, the following content will not distinguish between different power conversion circuits, but will use any power conversion circuit as an example to explain the control process in detail. Subsequent related embodiments will follow this premise.

[0041] Based on the above, the control module first acquires the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times. It is understood that in practical applications, the control module scans the output parameters of the photovoltaic module according to a preset scanning interval to determine the maximum power point of the power conversion circuit corresponding to the corresponding scanning cycle. In other words, multiple maximum power points can be obtained within a day's working cycle of the photovoltaic module. Based on this, during the maximum power point tracking process, whenever a stable maximum power point is determined, the control module can record the electrical parameters corresponding to that maximum power point, such as the voltage and power, or the voltage and current. It is understood that the sampling time mentioned in this embodiment can be the time point after the control module completes one tracking cycle and exits dynamic adjustment, to ensure that the recorded maximum power point data is stable. For example, the control module can record the maximum power point MPP1(V1, P1) at sampling time t1 and the maximum power point MPP2(V2, P2) at sampling time t2, recording the electrical parameters of at least two maximum power points in total.

[0042] After obtaining the electrical parameters corresponding to at least two maximum power points, the control module further determines the target parameter change rate based on the electrical parameters of at least two maximum power points.

[0043] Specifically, two maximum power points are selected from at least two stored maximum power points, defined as the first maximum power point and the second maximum power point. Various optional implementation methods can be adopted for selecting the first and second maximum power points. For example, two maximum power points that are temporally adjacent can be selected, or the first and last maximum power points among all maximum power points can be selected. Of course, other methods can also be selected, which will not be detailed here. Without departing from the core idea of ​​this application, they also fall within the scope of protection of this application.

[0044] In one optional implementation, the electrical parameters of the maximum power point are obtained as voltage and power values. Based on this, the electrical parameters corresponding to the first maximum power point are represented as (P1, V1), where P1 represents the first power value corresponding to the first maximum power point, and V1 represents the first voltage value corresponding to the first maximum power point. The electrical parameters corresponding to the second maximum power point are represented as (P2, V2), where P2 represents the second power value corresponding to the second maximum power point, and V2 represents the second voltage value corresponding to the second maximum power point. The difference between the first power value P1 and the second power value P2 is calculated, and the result is taken as the target power deviation. The difference between the first voltage value V1 and the second voltage value V2 is calculated, and the result is taken as the first voltage deviation. The ratio of the target power deviation to the first voltage deviation is determined as the target parameter change rate. Specifically, the target parameter change rate can be calculated according to the following formula: (1) Where k represents the rate of change of the target parameter.

[0045] It is understandable that the rate of change of the target parameter calculated based on formula (1) can reflect the slope of the curve of power changing with voltage. Through the rate of change of the target parameter, the characteristics of the change of the maximum power point as the operating point moves can be quantitatively analyzed.

[0046] In another optional implementation, the electrical parameters of the maximum power point are obtained as current and voltage values. Based on this, the electrical parameters corresponding to the first maximum power point are represented as (I1, V1), where I1 represents the first current value corresponding to the first maximum power point, and V1 represents the first voltage value corresponding to the first maximum power point. The electrical parameters corresponding to the second maximum power point are represented as (I2, V2), where I2 represents the second current value corresponding to the second maximum power point, and V2 represents the second voltage value corresponding to the second maximum power point. The difference between the first current value I1 and the second current value I2 is calculated, and the result is taken as the target current deviation; the difference between the first voltage value V1 and the second voltage value V2 is calculated, and the result is taken as the second voltage deviation; the ratio of the target current deviation to the first voltage deviation is determined as the target parameter change rate. Specifically, the target parameter change rate can be calculated according to the following formula: (1) The rate of change k of the target parameter, calculated based on the current and voltage values, represents the local slope of the curve showing the change in current versus voltage. This rate of change of the target parameter can also be used to quantitatively analyze the characteristics of the maximum power point as the operating point moves.

[0047] The control module further determines the shading status of the photovoltaic modules connected to the power conversion circuit based on the relationship between the target parameter change rate and the preset parameter change range.

[0048] It should be noted that the preset parameter variation range provided in this embodiment is determined based on the actual shading situation of the photovoltaic module and the historical operating data of the power conversion circuit under the corresponding shading situation, and can be multiple numerical ranges. The control module determines the shading state of the photovoltaic module by judging the relationship between the currently calculated target parameter change rate and the variation range of each preset parameter. It can be understood that, combined with the actual application scenario of the photovoltaic module, the shading situation of the photovoltaic module may include, but is not limited to, the unshaded state with only one maximum power point, the transitional state with shading but still corresponding to one maximum power point, and the shaded state with at least two local maximum power points. It should be emphasized that the aforementioned transitional state generally refers to the situation where the photovoltaic module is shaded but its PV curve still shows a single maximum power point. This state is between the single-peak state of no shading and the multi-peak state of forming multiple local maximum power points. As for the specific calibration process of the preset parameter variation range, it will be elaborated in detail in subsequent embodiments and will not be described here.

[0049] In one implementation, the photovoltaic module is in an unshaded state, and the PV curves of the power conversion circuit at multiple different sampling times can be referenced. Figure 3a As shown, it is understandable that Figure 3a Each curve (drawn as a solid line) corresponds to a sampling time, and the irradiance at each sampling time is different. Furthermore, combined with... Figure 1 As can be seen from the example shown, Figure 3a Each curve in the graph corresponds to a unique maximum power point (which can also be defined as the global maximum power point). Connecting the maximum power points at different sampling times yields the result. Figure 3a The curve A shown represents the rate of change of the target parameter calculated according to the aforementioned steps, which is the slope of the local curve corresponding to curve A.

[0050] Based on this, the preset parameter variation range includes a first preset parameter variation range. This first preset parameter variation range is determined based on historical operating data of the power conversion circuit under unshaded conditions of the photovoltaic module. The lower limit of the first preset parameter variation range is denoted as k2, and the upper limit is denoted as k1. See [link to relevant documentation]. Figure 3b As shown, the intervals corresponding to k1 and k2 represent the range of variation of the first preset parameter. If the obtained rate of change of the target parameter, i.e., the local slope corresponding to curve A, is within the range of variation of the first preset parameter, it can be determined that the photovoltaic module is not shaded and corresponds to a maximum power point. Conversely, if the obtained rate of change of the target parameter is not within the range of variation of the first preset parameter, it can be determined that the photovoltaic module is shaded.

[0051] In another implementation, the photovoltaic modules are in a shaded state. Based on the foregoing, the shaded state of the photovoltaic modules can be further subdivided into two cases according to the number of maximum power points. Figure 4aAs shown, except for the curve corresponding to the maximum power point (i.e., the curve with the largest power value), Figure 4a Apart from the only single-peak curve in the circuit, each PV curve (drawn as a solid line) of the power conversion circuit corresponds to two local maximum power points. By fitting these local maximum power points, curves B and C can be obtained. Correspondingly, based on the process of the PV curve of the power conversion circuit transitioning from multi-peak to single-peak, we can also obtain... Figure 4a Curve D, as shown, represents the transition process of a photovoltaic module from being shaded to being unshaded; at this point, the photovoltaic module is in a transitional state. The rate of change of the target parameter calculated according to the aforementioned calculation process can be the local slope corresponding to any one of curves B, C, and D.

[0052] The preset parameter variation range also includes a second preset parameter variation range and at least one third preset parameter variation range. The second and third preset parameter variation ranges are determined based on historical operating data of the power conversion circuit under shading conditions of the photovoltaic modules, and both the upper and lower limits of the second preset parameter variation range are negative. Combined with... Figure 4b As shown, k3, k4, k5, k6, k7, and k8 are all limits of the preset parameter range, and can also characterize the slope of the power-voltage change curve. Specifically, the slope range corresponding to k3 and k4 is the second preset parameter change range, the slope range corresponding to k5 and k6 is a third preset parameter change range, and the slope range corresponding to k7 and k8 is another third preset parameter change range.

[0053] Based on the above, if the rate of change of the target parameter calculated in the aforementioned steps is within the range of the second preset parameter, it is determined that the photovoltaic module is in a transitional state, and it is determined that the photovoltaic module is shaded but corresponds to a maximum power point (i.e., it is still a single-peak curve). If the rate of change of the target parameter is within the range of any third preset parameter, it is determined that the photovoltaic module is shaded and corresponds to at least two local maximum power points (i.e., a multi-peak curve has been formed).

[0054] In summary, the power converter provided in this application embodiment allows the control module to acquire electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times, determine the target parameter change rate based on the obtained electrical parameters of at least two maximum power points, and determine the shading status of the photovoltaic modules connected to the power conversion circuit based on the relationship between the target parameter change rate and the preset parameter change range. This solves the problem that related technologies cannot identify whether photovoltaic modules are shading, and can provide a reference for the operation control of the power converter, reducing power generation losses caused by shading.

[0055] Furthermore, when the photovoltaic module connected to the power conversion circuit corresponds to at least two local maximum power points, the control module drives the power conversion circuit to adjust the output power of the photovoltaic module until the power conversion circuit operates at the global maximum power point, thereby maximizing the utilization of the photovoltaic module's electrical power. In this embodiment, the global maximum power point refers to the local maximum power point whose power value is greater than that of any other local maximum power point. See also... Figure 5 As shown, assuming the PV curve corresponding to the current sampling time is S0, it includes a local maximum power point N and a local maximum power point M. The power value P1 of the local maximum power point M is greater than the power value P2 of the local maximum power point N. Therefore, the local maximum power point M is the global maximum power point at the current sampling time. Furthermore, the voltage corresponding to the maximum power point M is V1, and the voltage corresponding to the maximum power point N is V2.

[0056] Based on the above, as an optional implementation, the control module drives the power conversion circuit to reduce the output voltage of the photovoltaic module until it reaches a preset basic voltage. This preset basic voltage is the minimum voltage required for the power conversion circuit to operate. It is understood that during the voltage reduction process, the output power of the photovoltaic module will increase accordingly. The control module records the power value during the voltage reduction process until it finds the local power point M with the largest power value, which is taken as the global maximum power point. Then, the operating point is adjusted to this global maximum power point and continuously tracked. It should be noted that after determining the global maximum power point, the power conversion circuit can be controlled according to the MPPT algorithm provided by relevant technologies, which will not be detailed here. Figure 5 As shown, the control power conversion circuit starts from the local maximum power point N(P2, V2), traverses the PV curve to M(P1, V1), and after perturbation comparison, determines point M as the global maximum power point, so that the system can operate at point M and ensure that the system always obtains power from the global maximum power point.

[0057] Of course, the global maximum power point can also be determined in other ways, still using... Figure 5 As shown in the example, assuming the power conversion circuit is currently operating at point N, the control module drives the power conversion circuit to reduce the output voltage of the photovoltaic module to increase the output power of the photovoltaic module. When the power deviation between the output power P0 of the photovoltaic module and the power value corresponding to point N is greater than the power threshold, the continuous voltage reduction process can be paused, and the power conversion circuit can be controlled to operate according to the MPPT algorithm provided by the relevant technology. Based on P0, maximum power point tracking is performed until the global maximum power point M is reached.

[0058] The power converter provided in this embodiment can not only identify whether the photovoltaic module is shaded, providing a reference for the operation control of the power converter, but also drive the power converter to operate at the global maximum power point, maximizing the utilization of the electric power of the photovoltaic module and providing power generation for the power converter and its system.

[0059] It is understandable that the output power of a photovoltaic module is positively correlated with the irradiance, while the irradiance is negatively correlated with the shading area of ​​the photovoltaic module. That is, the larger the shading area, the lower the irradiance, and vice versa. Thus, it can be seen that the power of the power conversion circuit (i.e., the output power of the photovoltaic module) is specifically correlated with the shading area of ​​the photovoltaic module. Therefore, the change in the shading area of ​​the photovoltaic module can be identified by the change in the electrical parameters corresponding to the maximum power point of the power conversion circuit.

[0060] Based on this, in the power converter provided in this application embodiment, the control module, after acquiring at least three maximum power point electrical parameters, can also calculate the parameter change rate corresponding to the electrical parameters of any two adjacent maximum power points, obtaining multiple parameter change rates. The calculation process for any parameter change rate can be implemented by referring to the calculation process for the target parameter change rate provided in the aforementioned embodiment, and will not be repeated here. After obtaining multiple parameter change rates, the control module determines the change in the shading area of ​​the photovoltaic module based on the temporal trend of each parameter change rate. Specifically, if the parameter change rates increase sequentially in chronological order, it indicates that the shading area of ​​the photovoltaic module is gradually decreasing; conversely, if the parameter change rates decrease sequentially in chronological order, it indicates that the shading area of ​​the photovoltaic module is gradually increasing. Through the continuously calculated parameter change rate sequence, it is possible to infer whether the shading is in a worsening or improving trend, providing a reference for subsequent operation and maintenance.

[0061] The process of determining the range of preset parameter variations mentioned in any of the foregoing embodiments is described below.

[0062] The control module obtains the actual shading status of the photovoltaic module, such as whether it is unshaded or shaded. The control module also needs to synchronously obtain the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times under the actual shading status. The specific selection of electrical parameters can be referred to the relevant content of the aforementioned embodiments, and will not be repeated here.

[0063] After obtaining the actual shading conditions of the photovoltaic modules and the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times under these conditions, the control module fits a reference curve based on the electrical parameters corresponding to each maximum power point. This reference curve can be a curve showing the maximum power point changing with voltage or a curve showing the maximum power point changing with current. The slope of this reference curve is then determined. In practical applications, there are various ways to fit a reference curve based on the electrical parameters of the maximum power points. For example, it can be done through least-squares linear fitting, or by calculating the slope between two points. This application does not limit the specific fitting process for the reference curve. After determining the slope of the reference curve, the preset parameter variation range corresponding to the actual shading conditions can be determined based on this slope.

[0064] Specifically, under known shading conditions, the control module can record the electrical parameters of the maximum power point (MPP) tracked by the power conversion circuit at multiple sampling times. For example, in the unshaded condition, the recorded MPP sequence would be MPP1(V1,P1), MPP2(V2,P2), ..., MPPn(Vn,Pn). Plotting these points on a voltage-power coordinate system yields an approximately smooth curve, such as... Figure 3a Curve A is shown. The control module determines the slope of the reference curve as the reference curve slope, and determines the range of preset parameter variations corresponding to the actual occlusion situation based on the reference curve slope. For example, the slope of the tangent between all two adjacent maximum power points of the reference curve can be taken, and its numerical distribution range can be statistically analyzed. For example, the typical range of the slope of the curve near the maximum power point can be obtained by fitting, which is k5 to k6 (k6≤k5). This range is used as the first preset parameter variation range. It should be noted that the fitting can be done by using polynomial regression or spline interpolation, obtaining a continuous curve and then differentiating it to obtain the reference curve slope. Alternatively, the difference slope between discrete points can be used directly for statistical analysis, which will not be detailed here. As for the aforementioned second and third preset parameter variation ranges, they can be obtained by referring to the above methods, which will not be detailed here.

[0065] Furthermore, the preset parameter variation range can also support dynamic updates. The control module can periodically (e.g., during sunrise each day or after each change in shading status) re-collect the maximum power point sequence, updating the reference curve and the corresponding slope range to adapt to long-term changes such as photovoltaic module aging, temperature drift, or dust accumulation. For example, after the system has been running for a period of time, if the control module detects a systematic deviation between the currently tracked maximum power point slope distribution and the historically stored preset range, it will automatically trigger a refitting process, replacing the old value with the new slope range, thereby maintaining the accuracy of shading diagnosis.

[0066] This application also provides a maximum power point tracking method applied to a power converter. The specific architecture of this power converter can be found in [reference needed]. Figure 2 As shown, it will not be repeated here. The maximum power point tracking method provided in this embodiment may include, for example, Figure 6 The following steps are shown.

[0067] S100: Obtain the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times.

[0068] During maximum power point tracking (MPPT), the control module records the electrical parameters corresponding to a stable maximum power point whenever it determines one. These parameters may include the voltage and power, or the voltage and current corresponding to that maximum power point. It is understood that the sampling time described in this embodiment can be the time point after the control module completes one tracking cycle and exits dynamic adjustment, ensuring that the recorded data is stable maximum power point data. For example, the control module can record the maximum power point MPP1(V1, P1) at sampling time t1 and the maximum power point MPP2(V2, P2) at sampling time t2, recording the electrical parameters of at least two maximum power points.

[0069] S110. Determine the rate of change of the target parameter based on the electrical parameters of at least two maximum power points.

[0070] Select two maximum power points from at least two stored maximum power points, and define them as the first maximum power point and the second maximum power point.

[0071] In one optional implementation, the electrical parameters of the maximum power point are obtained as voltage and power values. Based on this, the electrical parameters corresponding to the first maximum power point are represented as (P1, V1), where P1 represents the first power value corresponding to the first maximum power point, and V1 represents the first voltage value corresponding to the first maximum power point. The electrical parameters corresponding to the second maximum power point are represented as (P2, V2), where P2 represents the second power value corresponding to the second maximum power point, and V2 represents the second voltage value corresponding to the second maximum power point. The difference between the first power value P1 and the second power value P2 is calculated, and the result is taken as the target power deviation. The difference between the first voltage value V1 and the second voltage value V2 is calculated, and the result is taken as the first voltage deviation. The ratio of the target power deviation to the first voltage deviation is determined as the target parameter change rate.

[0072] In another optional implementation, the electrical parameters of the maximum power point are obtained as current and voltage values. Based on this, the electrical parameters corresponding to the first maximum power point are represented as (I1, V1), where I1 represents the first current value corresponding to the first maximum power point, and V1 represents the first voltage value corresponding to the first maximum power point. The electrical parameters corresponding to the second maximum power point are represented as (I2, V2), where I2 represents the second current value corresponding to the second maximum power point, and V2 represents the second voltage value corresponding to the second maximum power point. The difference between the first current value I1 and the second current value I2 is calculated, and the result is taken as the target current deviation; the difference between the first voltage value V1 and the second voltage value V2 is calculated, and the result is taken as the second voltage deviation; the ratio of the target current deviation to the first voltage deviation is determined as the target parameter change rate.

[0073] S120. Based on the relationship between the target parameter change rate and the preset parameter change range, determine the shading status of the photovoltaic modules connected to the power conversion circuit.

[0074] In one implementation, the photovoltaic module is in an unshaded state, and the PV curves of the power conversion circuit at multiple different sampling times can be referenced. Figure 3a As shown, it is understandable that Figure 3a Each curve (drawn as a solid line) corresponds to a sampling time, and the irradiance at each sampling time is different. Furthermore, combined with... Figure 1 As can be seen from the example shown, Figure 3a Each curve in the graph corresponds to a unique maximum power point (which can also be defined as the global maximum power point). Connecting the maximum power points at different sampling times yields the result. Figure 3a The curve A shown represents the rate of change of the target parameter calculated according to the aforementioned steps, which is the slope of the local curve corresponding to curve A.

[0075] Based on this, the preset parameter variation range includes a first preset parameter variation range. This first preset parameter variation range is determined based on historical operating data of the power conversion circuit under unshaded conditions of the photovoltaic module. The lower limit of the first preset parameter variation range is denoted as k2, and the upper limit is denoted as k1. See [link to relevant documentation]. Figure 3b As shown, the curves corresponding to lines k1 and k2 represent the range of variation of the first preset parameter. If the rate of change of the target parameter, i.e., the local slope corresponding to curve A, is within the range of variation of the first preset parameter, it can be determined that the photovoltaic module is not shaded and corresponds to a maximum power point. Conversely, if the rate of change of the target parameter is not within the range of variation of the first preset parameter, it can be determined that the photovoltaic module is shaded.

[0076] In another implementation, the photovoltaic modules are in a shaded state. Based on the foregoing, the shaded state of the photovoltaic modules can be further subdivided into two cases according to the number of maximum power points. Figure 4a As shown, except for the curve corresponding to the maximum power point (i.e., the curve with the largest power value), Figure 4a Apart from the only single-peak curve in the circuit, each PV curve (drawn as a solid line) of the power conversion circuit corresponds to two local maximum power points. By fitting these local maximum power points, curves B and C can be obtained. Correspondingly, based on the process of the PV curve of the power conversion circuit transitioning from multi-peak to single-peak, we can also obtain... Figure 4a Curve D, as shown, represents the transition process of a photovoltaic module from being shaded to being unshaded; at this point, the photovoltaic module is in a transitional state. The rate of change of the target parameter calculated according to the aforementioned calculation process can be the local slope corresponding to any one of curves B, C, and D.

[0077] The preset parameter variation range also includes a second preset parameter variation range and at least one third preset parameter variation range. The second and third preset parameter variation ranges are determined based on historical operating data of the power conversion circuit under shading conditions of the photovoltaic modules, and both the upper and lower limits of the second preset parameter variation range are negative. Combined with... Figure 4b As shown, k3, k4, k5, k6, k7, and k8 are all limits of the preset parameter range, and can also characterize the slope of the power-voltage change curve. Specifically, the slope range corresponding to k3 and k4 is the second preset parameter change range, the slope range corresponding to k5 and k6 is a third preset parameter change range, and the slope range corresponding to k7 and k8 is another third preset parameter change range.

[0078] Based on the above, if the rate of change of the target parameter calculated in the aforementioned steps is within the range of the second preset parameter, it is determined that the photovoltaic module is in a transitional state, and it is determined that the photovoltaic module is shaded but corresponds to a maximum power point (i.e., it is still a single-peak curve). If the rate of change of the target parameter is within the range of any third preset parameter, it is determined that the photovoltaic module is shaded and corresponds to at least two local maximum power points (i.e., a multi-peak curve has been formed).

[0079] In summary, the maximum power point tracking method provided in this application obtains the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times, determines the target parameter change rate based on the obtained electrical parameters of at least two maximum power points, and determines the shading status of the photovoltaic module connected to the power conversion circuit based on the relationship between the target parameter change rate and the preset parameter change range. This solves the problem that related technologies cannot identify whether photovoltaic modules are shaded, and can provide a reference for the operation control of the power converter, reducing power generation losses caused by shading.

[0080] Furthermore, when the photovoltaic modules connected to the power conversion circuit correspond to at least two local maximum power points, the control module drives the power conversion circuit to adjust the output power of the photovoltaic modules until the power conversion circuit operates at the global maximum power point, thereby maximizing the utilization of the photovoltaic module's electrical power. As an optional implementation, the control module drives the power conversion circuit to reduce the output voltage of the photovoltaic modules until it reaches a preset basic voltage, which is the minimum voltage required for the power conversion circuit to operate. It is understood that during the voltage reduction process, the output power of the photovoltaic modules will increase accordingly. The control module records the power value during the voltage reduction process until it finds the local power point M with the largest power value, which is taken as the global maximum power point. Then, the operating point is adjusted to this global maximum power point and continuously tracked. It should be noted that after determining the global maximum power point, the power conversion circuit can be controlled according to the MPPT algorithm provided by relevant technologies, which will not be detailed here.

[0081] As an optional implementation, after acquiring electrical parameters for at least three maximum power points, the control module can also calculate the parameter change rate corresponding to the electrical parameters of any two adjacent maximum power points, obtaining multiple parameter change rates. The calculation process for any parameter change rate can be implemented by referring to the calculation process for the target parameter change rate provided in the aforementioned embodiment, and will not be repeated here. After obtaining multiple parameter change rates, the control module determines the change in the shading area of ​​the photovoltaic module based on the temporal trend of each parameter change rate. Specifically, if the parameter change rates increase sequentially over time, it indicates that the shading area of ​​the photovoltaic module is gradually decreasing; conversely, if the parameter change rates decrease sequentially over time, it indicates that the shading area of ​​the photovoltaic module is gradually increasing. Through the continuously calculated sequence of parameter change rates, it is possible to infer whether the shading is in a worsening or improving trend, providing a reference for subsequent operation and maintenance.

[0082] Furthermore, in the maximum power point tracking method provided in this application embodiment, the range of preset parameter variations can be determined by referring to the following process.

[0083] The control module obtains the actual shading status of the photovoltaic module, such as whether it is unshaded or shaded. The control module also needs to synchronously obtain the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times under the actual shading status. The specific selection of electrical parameters can be referred to the relevant content of the aforementioned embodiments, and will not be repeated here.

[0084] After obtaining the actual shading conditions of the photovoltaic modules and the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times under these conditions, the control module fits a reference curve based on the electrical parameters corresponding to each maximum power point. This reference curve can be a curve showing the maximum power point changing with voltage or a curve showing the maximum power point changing with current. The slope of this reference curve is then determined. After determining the slope of the reference curve, the preset parameter variation range corresponding to the actual shading conditions can be determined based on this slope.

[0085] This application also provides a power supply system, including the power converter provided in any of the foregoing embodiments.

[0086] Below, for reference Figure 7 The controller provided in this application embodiment can be described as follows: at least one processor 100, at least one communication interface 200, at least one memory 300 and at least one communication bus 400. In this embodiment, the number of processor 100, communication interface 200, memory 300, and communication bus 400 is at least one, and the processor 100, communication interface 200, and memory 300 communicate with each other through communication bus 400; obviously, Figure 7 The communication connections shown for the processor 100, communication interface 200, memory 300, and communication bus 400 are optional. Optionally, the communication interface 200 can be an interface of a communication module, such as the interface of a GSM module; the processor 100 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0087] The memory 300 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0088] Specifically, the processor 100 is used to execute the application program in the memory to implement the steps of the maximum power point tracking method described above.

[0089] In some embodiments, this embodiment also provides a computer-readable storage medium, such as a floppy disk, optical disk, hard disk, flash memory, USB flash drive, SD (Secure Digital Memory Card), MMC (Multimedia Card), etc., in which one or more instructions implementing the above steps are stored. When these one or more instructions are executed by one or more processors, the processors perform the maximum power point tracking method described above. For specific implementation details, please refer to the foregoing description; further elaboration is not provided here.

[0090] In addition to the methods and apparatus described above, embodiments of this application may also be computer program products, which include computer program instructions that, when executed by a processor, cause the processor to perform the steps in the maximum power point tracking methods according to various embodiments of this application as described above.

[0091] Computer program products can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of this application. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0092] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0093] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0094] Those skilled in the art will understand that the contents disclosed herein can be varied and modified in many ways. For example, the various devices or components described above can be implemented in hardware, or in software, firmware, or a combination of some or all of the three.

[0095] Furthermore, while this disclosure makes various references to certain elements of systems according to embodiments of this disclosure, any number of different elements may be used and operated on clients and / or servers. Elements are merely illustrative, and different aspects of the system and method may use different elements.

[0096] This disclosure uses flowcharts to illustrate the steps of a method according to embodiments of this disclosure. It should be understood that the preceding or following steps are not necessarily performed in exact order. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these processes.

[0097] Those skilled in the art will understand that all or part of the steps in the above methods can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium, such as a read-only memory. Optionally, all or part of the steps in the above embodiments can also be implemented using one or more integrated circuits. Accordingly, each module / unit in the above embodiments can be implemented in hardware or as a software functional module. This disclosure is not limited to any particular combination of hardware and software.

[0098] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It should also be understood that terms such as those defined in a common dictionary should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and not as having an idealized or highly formalized meaning, unless expressly defined herein.

[0099] The foregoing description is intended to illustrate the present disclosure and should not be construed as limiting it. While several exemplary embodiments of the present disclosure have been described, those skilled in the art will readily understand that many modifications may be made to the exemplary embodiments without departing from the novel teachings and advantages of the present disclosure. Therefore, all such modifications are intended to be included within the scope of the present disclosure as defined by the claims. It should be understood that the foregoing description is intended to illustrate the present disclosure and should not be construed as limiting it to the specific embodiments disclosed, and modifications to the disclosed embodiments and other embodiments are intended to be included within the scope of the appended claims. The present disclosure is defined by the claims and their equivalents.

Claims

1. A power converter, characterized in that, include: A power conversion circuit, wherein the input side of the power conversion circuit is connected to the photovoltaic module; The control module is connected to the control terminal of the power conversion circuit; The control module is configured as follows: Obtain the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times; The target parameter change rate is determined based on the electrical parameters of the at least two maximum power points; Based on the relationship between the rate of change of the target parameter and the range of change of the preset parameter, the shading status of the photovoltaic module connected to the power conversion circuit is determined. The range of variation of the preset parameters is determined based on the actual shading of the photovoltaic module and the historical operating data of the power conversion circuit.

2. The power converter according to claim 1, characterized in that, The preset parameter variation range includes a first preset parameter variation range, which is determined based on the historical operating data of the power conversion circuit under unshaded conditions of the photovoltaic module. The control module is specifically configured as follows: If the rate of change of the target parameter is within the range of the first preset parameter, it is determined that the photovoltaic module connected to the power conversion circuit is not shaded and corresponds to a maximum power point. If the rate of change of the target parameter is not within the range of the first preset parameter, it is determined that the photovoltaic module connected to the power conversion circuit is shaded.

3. The power converter according to claim 2, characterized in that, The preset parameter variation range also includes a second preset parameter variation range and at least one third preset parameter variation range. The second preset parameter variation range and the third preset parameter variation range are determined based on the historical operating data of the power conversion circuit when the photovoltaic module is shaded. The upper limit and lower limit of the second preset parameter variation range are both negative. The control module is specifically configured as follows: If the rate of change of the target parameter is within the range of the second preset parameter, it is determined that the photovoltaic module connected to the power conversion circuit is in a transition state. The transition state refers to the photovoltaic module being shaded and corresponding to a maximum power point. If the rate of change of the target parameter is within the range of any of the third preset parameters, it is determined that the photovoltaic module connected to the power conversion circuit is shaded and corresponds to at least two local maximum power points.

4. The power converter according to claim 3, characterized in that, The electrical parameters of at least two maximum power points include electrical parameters of three or more maximum power points; The control module is also configured to: Calculate the rate of change of electrical parameters for any two adjacent maximum power points to obtain multiple rate of change of parameters. The change in the shading area of ​​the photovoltaic module is determined based on the time-series trend of the change rate of each parameter.

5. The power converter according to claim 4, characterized in that, The control module is specifically configured as follows: If the rate of change of each parameter increases sequentially in chronological order, it is determined that the shading area of ​​the photovoltaic module gradually decreases. If the rate of change of each parameter decreases sequentially in chronological order, it is determined that the shading area of ​​the photovoltaic module gradually increases.

6. The power converter according to claim 3, characterized in that, When the photovoltaic modules connected to the power conversion circuit correspond to at least two local maximum power points, the control module is further configured to: The power conversion circuit is driven to adjust the output power of the photovoltaic module until the power conversion circuit operates at the global maximum power point, where the power value of the global maximum power point is greater than the power value of any other local maximum power point.

7. The power converter according to claim 6, characterized in that, The control module is specifically configured as follows: The power conversion circuit is driven to reduce the output voltage of the photovoltaic module until it reaches a preset base voltage. The local power point with the largest power value during the reduction of the output voltage of the photovoltaic module is determined as the global maximum power point. The preset base voltage is the minimum voltage that meets the operating requirements of the power conversion circuit.

8. The power converter according to claim 1, characterized in that, The electrical parameters of the at least two maximum power points include a first power value and a first voltage value corresponding to the first maximum power point, and a second power value and a second voltage value corresponding to the second maximum power point; The control module is specifically configured as follows: The difference between the first power value and the second power value is determined as the target power deviation; The difference between the first voltage value and the second voltage value is determined as the first voltage deviation; The ratio of the target power deviation to the first voltage deviation is determined as the rate of change of the target parameter.

9. The power converter according to claim 1, characterized in that, The electrical parameters of the at least two maximum power points include a first current value and a first voltage value corresponding to the first maximum power point, and a second current value and a second voltage value corresponding to the second maximum power point. The control module is specifically configured as follows: The difference between the first current value and the second current value is determined as the target current deviation; The difference between the first voltage value and the second voltage value is determined as the second voltage deviation; The ratio of the target current deviation to the second voltage deviation is determined as the rate of change of the target parameter.

10. The power converter according to any one of claims 1 to 9, characterized in that, The control module is also configured to: The actual shading status of the photovoltaic module and the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times are obtained. The reference curves are fitted based on the electrical parameters corresponding to each of the maximum power points, and the reference curves include the curves of each of the maximum power points changing with voltage, or the curves of each of the maximum power points changing with current. Determine the slope of the reference curve; The range of preset parameter variations corresponding to the actual occlusion situation is determined based on the slope of the reference curve.

11. A maximum power point tracking method, characterized in that, The method, applied to a power converter including a power conversion circuit and having its input connected to a photovoltaic module, comprises: Obtain the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times; The target parameter change rate is determined based on the electrical parameters of the at least two maximum power points; Based on the relationship between the rate of change of the target parameter and the range of change of the preset parameter, the shading status of the photovoltaic module connected to the power conversion circuit is determined. The range of variation of the preset parameters is determined based on the actual shading of the photovoltaic module and the historical operating data of the power conversion circuit.

12. The method according to claim 11, characterized in that, The preset parameter variation range includes a first preset parameter variation range, which is determined based on the historical operating data of the power conversion circuit under unshaded conditions of the photovoltaic module. The step of determining the shading status of the photovoltaic modules connected to the power conversion circuit based on the relationship between the target parameter change rate and the preset parameter change range includes: If the rate of change of the target parameter is within the range of the first preset parameter, it is determined that the photovoltaic module connected to the power conversion circuit is not shaded and corresponds to a maximum power point. If the rate of change of the target parameter is not within the range of the first preset parameter, it is determined that the photovoltaic module connected to the power conversion circuit is shaded.

13. The method according to claim 12, characterized in that, The preset parameter variation range further includes a second preset parameter variation range and at least one third preset parameter variation range. The second preset parameter variation range and the third preset parameter variation range are determined based on historical operating data of the power conversion circuit under shading conditions of the photovoltaic module, and the upper and lower limits of the second preset parameter variation range are both negative. The method further includes: If the rate of change of the target parameter is within the range of the second preset parameter, it is determined that the photovoltaic module connected to the power conversion circuit is in a transition state. The transition state refers to the photovoltaic module being shaded and corresponding to a maximum power point. If the rate of change of the target parameter is within the range of any of the third preset parameters, it is determined that the photovoltaic module connected to the power conversion circuit is shaded and corresponds to at least two local maximum power points.

14. The method according to claim 13, characterized in that, The electrical parameters of the at least two maximum power points include electrical parameters of three or more maximum power points, and the method further includes: Calculate the rate of change of electrical parameters for any two adjacent maximum power points to obtain multiple rate of change of parameters. If the rate of change of each parameter increases sequentially in chronological order, it is determined that the shading area of ​​the photovoltaic module gradually decreases. If the rate of change of each parameter decreases sequentially in chronological order, it is determined that the shading area of ​​the photovoltaic module gradually increases.

15. The method according to claim 13, characterized in that, When the photovoltaic module connected to the power conversion circuit corresponds to at least two local maximum power points, the method further includes: The power conversion circuit is driven to adjust the output power of the photovoltaic module until the power conversion circuit operates at the global maximum power point, where the power value of the global maximum power point is greater than the power value of any other local maximum power point.

16. The method according to any one of claims 11 to 15, characterized in that, The method further includes: The actual shading status of the photovoltaic module and the electrical parameters of at least two maximum power points tracked by the power conversion circuit at different sampling times are obtained. The reference curves are fitted based on the electrical parameters corresponding to each of the maximum power points, and the reference curves include the curves of each of the maximum power points changing with voltage, or the curves of each of the maximum power points changing with current. Determine the slope of the reference curve; The range of preset parameter variations corresponding to the actual occlusion situation is determined based on the slope of the reference curve.

17. A controller comprising a memory, a processor, and a computer program stored in the memory and executed by the processor, characterized in that, When the processor executes the computer program, it implements the steps of the maximum power point tracking method as described in any one of claims 11 to 16.

18. A power supply system, characterized in that, include: The power converter as described in any one of claims 1 to 10.

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