Tracking method and tracking device for appropriate power point

Abstract

The invention relates to a tracking method and a tracking device for a proper power point. Relates to the field of photovoltaic power generation. A switching power supply regulator is used for carrying out direct current to direct current power conversion on a photovoltaic module, in the power conversion stage, the gain of the switching power supply regulator is regulated within a range, and the gain tracks the upper limit of the range or the lower limit of the range, so that a proper power point of the photovoltaic module is tracked.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of photovoltaic power generation, and more specifically, to a method and a device for tracking a suitable power point. Background Art

[0002] When the photovoltaic power generation system is working normally, under certain temperature and sunshine intensity conditions, the photovoltaic cell array usually has a unique maximum power point. However, since the output characteristics of the photovoltaic cell array are affected by factors such as load status, sunshine intensity, and ambient temperature, the output voltage and current of the photovoltaic cell array will change greatly, making the output power unstable. If the power changes cannot be tracked in real time, the output efficiency of the photovoltaic system will be reduced.

[0003] It is worth noting that due to the complex nonlinear characteristics of the output characteristics of photovoltaic arrays, it is difficult to accurately determine the mathematical model to model them, and the analytical method cannot obtain the maximum power. In order to maximize the output power of the photovoltaic array, the industry uses corresponding control methods to track and control the maximum power of the photovoltaic array in real time to maximize the use of solar energy. This regulation process that ensures that the photovoltaic array continuously outputs the maximum power is called maximum power point tracking.

[0004] For maximum power point tracking, currently, common tracking control methods include constant voltage control method, perturbation observation method, incremental admittance, single chaos search, and even application of artificial intelligence algorithms. However, different methods have different advantages and disadvantages in actual use. There are many reasons for the mismatch of photovoltaic modules, including foreign object shading and floating clouds, obstruction and surface pollution of nearby objects, different installation angles, installation orientations, aging, temperature changes and other factors. The mismatch of photovoltaic modules will induce unbalanced power loss of photovoltaic modules.

[0005] Simply pursuing the maximum power point of each photovoltaic module may not be the best choice. Typically, if some photovoltaic modules do not necessarily operate continuously at the maximum power point, they can leave the elastic voltage or current space required for series and parallel connection for the remaining photovoltaic modules in the network, and the photovoltaic power generation system will be more robust and stable in operation. Even from a system-level perspective, the entire photovoltaic system is allowed to pursue greater power output. This application will solve these problems. Summary of the invention

[0006] The present application relates to a tracking method of a suitable power point MSPT (Most Suitable Point Tracking):

[0007] Using a switching power supply regulator (SMPS regulator) to implement DC to DC power conversion for photovoltaic modules;

[0008] During the power conversion stage, the gain of the switching power supply regulator is adjusted within a range, and the gain is allowed to track the upper limit or the lower limit of the range, thereby tracking the appropriate power point of the photovoltaic component.

[0009] The above method connects multiple switching power regulators in series or in parallel into a link, and each switching power regulator is used to track the appropriate power point of the corresponding photovoltaic component, and the scale of the range is compressed by tracking the maximum power point of the link.

[0010] In the above method, the way of compressing the scale of the range includes: reducing the gap between the upper limit and the lower limit.

[0011] The above method uses an inverter with an MPPT (Maximum Power Point Tracking) function to track the maximum power point of the link.

[0012] The above method utilizes a power conversion device with an MPPT (Maximum Power Point Tracking) function to track the maximum power point of the link.

[0013] In the above method, the way of compressing the scale of the range includes: making the upper limit and the lower limit coincide with each other.

[0014] In the above method, the situation where the upper limit and the lower limit coincide with each other includes: the situation where the photovoltaic module is not blocked.

[0015] In the above method, the situation where the upper and lower limits coincide includes: when the photovoltaic module operates at the maximum power point, the gain of the switching power supply regulator tends to coincide with the upper and lower limits.

[0016] In the above method, the situation where the upper and lower limits do not overlap includes: the photovoltaic module is not operating at the maximum power point, and the gain of the switching power supply regulator is between the upper limit and the lower limit.

[0017] In the above method, the situation where the upper limit and the lower limit coincide with each other includes the situation where all photovoltaic modules corresponding to the same link are not blocked.

[0018] In the above method, the situation where the upper limit and the lower limit do not coincide includes: the situation where the photovoltaic module is blocked.

[0019] In the above method, the situation where the upper limit and the lower limit do not coincide includes: among all photovoltaic modules corresponding to the same link, some photovoltaic modules are not shaded, but other photovoltaic modules are shaded.

[0020] In the above method, the upper limit is a preset specified value.

[0021] In the above method, the switching power regulator is equipped with a microprocessor for driving the switching power regulator to perform voltage or current conversion. The microprocessor adjusts the gain by changing the duty cycle of the switching power regulator when it is working, so that the gain approaches the specified value.

[0022] In the above method, the lower limit is the gain when the photovoltaic module is at a maximum power point and the switching power supply regulator has a maximum power output.

[0023] In the above method, multiple switching power regulators are connected in series or in parallel to form a link, and the manner of forcing the gain to track the lower limit includes: approaching the gain to the lower limit by tracking the maximum power point of the link.

[0024] In the above method, the lower limit is a preset specified value.

[0025] In the above method, the switching power supply regulator is equipped with a microprocessor for driving the switching power supply regulator to perform voltage or current conversion. The microprocessor adjusts the gain by changing the duty cycle of the switching power supply regulator when it is working, so that the gain approaches a specified value (such as a lower limit).

[0026] In the above method, the upper limit is the gain when the photovoltaic module is at a maximum power point and the switching power supply regulator has a maximum power output.

[0027] In the above method, multiple switching power regulators are connected in series or in parallel to form a link, and the way in which the gain tracks the upper limit includes: tracking the maximum power point of the link to approach the gain to the upper limit.

[0028] In the above method, the gain includes voltage gain or current gain.

[0029] The present application relates to a tracking device for a suitable power point MSPT (Most Suitable Point Tracking):

[0030] The invention comprises a digital power supply, which is used to implement DC to DC power conversion for the photovoltaic module. The gain of the digital power supply in the power conversion stage is set to operate within a range, and the purpose of tracking the appropriate power point of the photovoltaic module is achieved by allowing the gain of the digital power supply to track the upper limit or the lower limit of the range.

[0031] The above-mentioned suitable power point tracking device connects multiple digital power supplies in series into a link, and each digital power supply is used to track the suitable power point of the photovoltaic component corresponding to it, and the scale of the range is compressed by tracking the maximum power point of the link.

[0032] The above-mentioned tracking device for the appropriate power point compresses the scale of the range in the following manner: reducing the gap between the upper limit and the lower limit.

[0033] In the above-mentioned suitable power point tracking device, the digital power supply is configured with a microprocessor for driving the digital power supply to perform voltage conversion or current conversion. The microprocessor adjusts the gain by changing the duty cycle of the digital power supply when it is working so that the gain approaches a specified value, and the upper limit is a pre-set specified value.

[0034] The above-mentioned suitable power point tracking device connects multiple digital power supplies in series into a link, and the method of forcing the gain to track the lower limit includes: approaching the gain to the lower limit by tracking the maximum power point of the link, and the lower limit is the gain when the photovoltaic component is at the maximum power point state and the digital power supply has the maximum power output.

[0035] In the above-mentioned suitable power point tracking device, the digital power supply is configured with a microprocessor for driving the digital power supply to perform voltage conversion or current conversion. The microprocessor adjusts the gain by changing the duty cycle of the digital power supply when it is working so that the gain approaches a specified value, and the lower limit is a pre-set specified value.

[0036] The above-mentioned suitable power point tracking device connects multiple digital power supplies in series or in parallel into a link, and the method of forcing the gain to track the upper limit includes: approaching the gain to the upper limit by tracking the maximum power point of the link, and the upper limit is the gain when the photovoltaic component is in the maximum power point state and the digital power supply has the maximum power output. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to make the above purposes, features and advantages more understandable, the following text will explain the specific implementation methods in detail in conjunction with the drawings. After reading the following description and referring to the following drawings, the features and advantages of the present application will become apparent.

[0038] Figure 1 In the traditional solution, the inverter uniformly performs maximum power point tracking on multi-level photovoltaic modules connected in series.

[0039] Figure 2 In the traditional solution, each of the multi-stage PV modules connected in series performs maximum power point tracking individually.

[0040] Figure 3 This is an example of a traditional solution that uses the perturbation method to perform maximum power point tracking on an individual PV module.

[0041] Figure 4 This is an example of a suitable power point for using a switching power regulator to track a photovoltaic module in this application.

[0042] Figure 5It is to use a switching power regulator and track the appropriate power point of the PV panel based on the voltage gain.

[0043] Figure 6 It is to use a switching power regulator and track the appropriate power point of the PV panel based on current gain.

[0044] Figure 7 It is a switching power supply regulator including a step-down conversion circuit, a step-up conversion circuit, or a step-up / step-down conversion circuit.

[0045] Figure 8 This is the case where the upper and lower limits of the gain range do not coincide and the case where the upper and lower limits of the gain range coincide.

[0046] Fig. 9 The switching power regulators or digital power supplies are connected in parallel to form a link and perform maximum power tracking uniformly. DETAILED DESCRIPTION

[0047] The technical solutions disclosed in the present application will be clearly and completely described below in conjunction with specific embodiments. However, the embodiments described are only embodiments used for narrative explanation in the present application and are not all embodiments. Based on these embodiments, technicians in this field should realize that any solution obtained without creative work falls within the scope of protection of the present application.

[0048] See also Figure 1 , power optimizer or MPPT (Maximum Power Point Tracking) controller stands for Maximum Power Point Tracking Solar Controller. The method used to achieve the best power of photovoltaic modules is MPPT. Currently, it is common to connect all photovoltaic panels to a single inverter INVT to perform MPPT. This method can transfer the MPPT function to the photovoltaic inverter for unified control, and requires maximum power tracking control operations. When the lighting conditions of the panels are consistent, this system can work normally, but when some solar panels have performance mismatch or shadow shielding conditions, the power efficiency of this system will be greatly reduced. Therefore, it is introduced. Figure 2 The power optimization function of the power optimizer OPN.

[0049] See also Figure 1 After the photovoltaic modules PV1-PVN are connected in series, the inverter INVT uniformly optimizes the power of all the photovoltaic modules connected in series. At this time, centralized maximum power point tracking MPPT is executed.

[0050] See also Figure 1An example of reduced efficiency of the PV system when PV modules are mismatched or shaded: As shown in the figure, it can be assumed that the lighting conditions of PV module PV1 are very good, and the radiation of PV modules PV2 and PVN is low. For example, they are shaded. When the inverter INVT performs MPPT on the strings, PV module PV1 may reach its maximum power point while PV modules PV2 and PVN may not reach the maximum power point.

[0051] See also Figure 1 , multiple photovoltaic modules PV1-PVN are connected in series between busbars LA and LB: If multiple photovoltaic modules PV1-PVN are defined to form a string, then multiple strings are connected in parallel between busbars LA and LB. The photovoltaic power optimization shown in the figure often only attempts to achieve the optimal operating current of the DC bus multiplied by the optimal operating voltage from the perspective of the photovoltaic inverter INVT end, that is, to pursue the bus current I BUS Multiply by bus voltage V BUS The string current, i.e., bus current, and string voltage, i.e., bus voltage of a single string are set at their maximum power points.

[0052] See also Figure 1 The figure shows an example of a widely used photovoltaic power generation system, which connects all components in series and parallel and directly connects them to a centralized inverter to transmit electricity to the grid system. As shown in the figure, such a centralized framework can only perform maximum power regulation for the entire system, and cannot perform separate power tracking control of each panel or component in each string of the photovoltaic system through MPPT, so it cannot guarantee the maximum power output of each panel. As long as any photovoltaic component in the string is shielded from light, other normal components in the string will be affected, and the output power will be pulled to an unreasonable value, resulting in energy loss. It is necessary to improve centralized optimization.

[0053] See also Figure 2 , the photovoltaic modules PV1-PVN are still connected in series, but the inverter INVT does not implement power optimization for all the photovoltaic modules connected in series. Instead, the power optimizer performs distributed maximum power point tracking MPPT.

[0054] See also Figure 2Distributed maximum power point tracking is an improvement on centralized power point tracking. Each photovoltaic module or photovoltaic panel is equipped with a DC converter or power optimizer that performs maximum power tracking calculations. In a battery string, for example, the electric energy generated by the first-level photovoltaic module PV1 shown in the figure is converted by the first-level power optimizer OP1 to perform power optimization, and the electric energy generated by the second-level photovoltaic module PV2 is converted by the second-level power optimizer OP2 to perform power optimization. And so on, until the electric energy generated by the N-th photovoltaic module PVN is converted by the N-th power optimizer OPN to perform power optimization. N is a positive integer not less than 1.

[0055] See also Figure 2 ,and Figure 1 Compared with the centralized MPPT, MPPT is performed individually at the PV module, so each PV module can reach its own maximum power point independently. This is equivalent to configuring the working voltage and working current of the PV module to have no direct correlation with the output voltage and output current of the power optimizer.

[0056] See also Figure 2 The PV power optimization shown in the figure only attempts to achieve the optimal working current multiplied by the optimal working voltage of the PV module from the perspective of the local end of the PV module: For example, the power optimizer OPN attempts to achieve the working current I of the PV module PVN from the perspective of the local end of the PV module PVN PVN Multiply by the operating voltage V PVN If this product is maximized, the power optimizer OPN has successfully implemented power optimization for the photovoltaic module PVN.

[0057] See also Figure 2 , the output voltage of the first stage power optimizer OP1 is V O1 , the output voltage V corresponding to the second-stage power optimizer OP2 O2 , ... and so on, until the output voltage V of the Nth-stage power optimizer OPN ON The total string voltage of any photovoltaic cell string is calculated to be approximately V O1 +V O2 +…V ON =V BUS The power optimizer used in this case is also called a maximum power point tracker, which usually uses a specific type of topology circuit to search for the maximum power point and allow the DC converter to extract the maximum possible power from the PV panel.

[0058] See also Figure 2 If no measures are taken, assuming that the conventional power optimizer OP1-OPN has achieved the working current I of the photovoltaic module such as PVN through maximum power tracking PVNMultiply by the operating voltage V PVN Maximization. In this balanced state where the power is at its maximum, if the photovoltaic inverter INVT performs power optimization again, it means that the photovoltaic inverter INVT will change the bus current and bus voltage to pursue the bus current I BUS Multiply by bus voltage V BUS It is obvious that the tracking action of the inverter INVT will break the power balance of the traditional power optimizer OP1-OPN. At this time, it is extremely difficult to achieve working adaptation between the traditional power optimizer and the photovoltaic inverter and meet the optimization requirements of both.

[0059] See also Figure 2 In order to solve the above problems, the MPPT function of the photovoltaic inverter INVT can be abandoned, so as to overcome the disturbance of the back-end inverter to the front-end power optimizer. For example, some distributed power optimization solutions currently on sale only perform power optimization locally in the photovoltaic components PV1-PVN instead of in the inverter INVT. The inverter simply performs power conversion from DC to AC. This solution also has great inconvenience: because the existing photovoltaic inverters in photovoltaic power stations basically have MPPT functions, and the photovoltaic MPPT function is standard, few inverter merchants cancel the photovoltaic MPPT function to adapt to the photovoltaic component PV1-PVN local optimizer. Therefore, this makes it difficult for the power optimization function configured on the power optimizer side to adapt to the market demand. Whether it is a distributed photovoltaic power station or a centralized photovoltaic power station, it would rather give up the power optimizer with MPPT function than give up the MPPT function of the inverter. This is a comprehensive result based on the cost considerations of the photovoltaic power station, the final power optimization effect, and the convenience of use.

[0060] See also Figure 2 , especially mainstream photovoltaic systems are compatible with photovoltaic inverters with MPPT functions. Most of the various software architectures and hardware parts of photovoltaic systems are based on catering to photovoltaic inverters with MPPT functions. Such photovoltaic inverters have adapted to the ecological chain of standard photovoltaic systems. The software and hardware systems of photovoltaic power stations are also designed and laid out based on photovoltaic inverters with maximum power tracking. For many existing photovoltaic power stations or newly built photovoltaic power stations, abandoning the MPPT function of photovoltaic inverter INVT is unacceptable and will also lose the opportunity for secondary optimization.

[0061] See also Figure 3 , the power voltage P of the photovoltaic module PVN -V PVN In the curve, under the same environmental conditions, the photovoltaic module has a unique maximum output power point P MX At the maximum power point P MXOn the left, the curve 200A shows that the output power of the photovoltaic module increases linearly with the output voltage of the photovoltaic module. The maximum power point P MX After reaching the maximum power point P, the output power of the photovoltaic module represented by curve 200B drops rapidly, and the rate of drop is much faster than the rate of rise. It is necessary to stabilize the output voltage of the photovoltaic module, such as PVN, at the maximum power point P MX The corresponding working voltage V MP The figure assumes that the output voltage of the photovoltaic module PVN is V PVN The output power is P PVN .

[0062] See also Figure 3 , Figure 2 The traditional power optimizer OPN Figure 3 For example, if the working voltage of the photovoltaic module PVN is actively changed, assuming that the working voltage changes to a certain extent, the power change of the photovoltaic module PVN is DP. If DP / DV>0, the photovoltaic module PVN works on curve 200A. If DP / DV<0, the corresponding photovoltaic module PVN works on curve 200B. The MPPT algorithm allows the maximum power point P MX Natural oscillation.

[0063] See also Figure 2 In essence, photovoltaic modules are just a specific example of the object to be optimized. The power optimizer is not only compatible with crystalline silicon panels, but can also be matched with some thin-film batteries. Photovoltaic modules can also be replaced with chemical batteries, batteries, or storage batteries. The broader meaning of the power optimizer is to implement power optimization for different types of DC power supplies, such as wind power and fuel cells. Any solution for maximum power tracking of DC power supplies in the prior art is also applicable to the inverter or tracking device in this article. Common tracking methods include constant voltage method, conductance increment method, and perturbation observation method. The power tracking method of single chaotic search is also a solution, but the chaotic motion is ergodic and time-consuming.

[0064] See also Figure 2 If the current photovoltaic power optimization attempts to achieve the optimal working current multiplied by the optimal working voltage of the photovoltaic module only from the perspective of the local end of the photovoltaic module, it may not take into account the power optimization of the series-parallel system of all photovoltaic modules by the centralized photovoltaic inverter. The typical disadvantage of simply tracking the optimal working current multiplied by the optimal working voltage of the photovoltaic module is that the fluctuation range of its working voltage is limited near the maximum power point of the photovoltaic module, and the coordination between optimizers is difficult to adapt to the adjustment requirements of the inverter optimization action. Under this condition, the power optimizer cannot provide flexible string current and string voltage to meet the flexible series-parallel requirements of the components.

[0065] See also Figure 4This application takes into account the advantages and disadvantages of MPPT (Maximum Power Point Tracking) and proposes a tracking scheme of MSPT (Most Suitable Point Tracking) suitable for DC power sources such as photovoltaic modules, which is referred to as suitable power point tracking or most suitable power point tracking in this application.

[0066] See also Figure 3 , this application involves the concept of maximum power point MPP (Maximum Power Point).

[0067] See also Figure 4 , this application relates to the concept of Most Suitable Point (MSP).

[0068] See also Figure 4 The so-called MSPT in this application uses a switching power supply regulator (SMPS regulator) or a digital power supply (digital power supply) or an equivalent power conversion device. According to the main purpose of this article, their goal is to track the appropriate power point MSP, not the maximum power point MPP. Therefore, the switching power supply regulator or digital power supply or an equivalent power conversion device used by the so-called MSPT in this application can also be called a power optimizer, but they are different from traditional power optimizers and no longer directly pursue MPP.

[0069] See also Figure 4 Although there are differences between MSP and MPP, it is worth noting that the appropriate power point MSP may fall on the maximum power point MPP or may not fall on the maximum power point MPP.

[0070] See also Figure 5 , the first stage switching power supply regulator H1 output voltage U H1 , the output voltage U corresponding to the second-stage switching power supply regulator H2 H2 , ... and so on, until the output voltage U of the switching power supply regulator HN of the Nth stage HN The total string voltage on the string is calculated to be approximately U H1 +U H2 +…U HN =V BUS The switching power regulator used in this case is also called a suitable power point tracker, which usually uses Buck, Boost, Buck-Boost, CUK type topology circuits to search for the suitable power point MSP and requires the switching power regulator to extract the most suitable power from the photovoltaic module.

[0071] See also Figure 5, taking the series-connected switching power regulator H1-HN as an example for description. A battery string is installed in the photovoltaic module array, and the battery string is composed of series-connected photovoltaic modules PV1 to PVN. Each photovoltaic module or photovoltaic panel is equipped with a switching power regulator or optimizer that performs appropriate power tracking calculations. In a certain battery string, for example, the electric energy generated by the first-stage photovoltaic module PV1 is converted and tracked by the first-stage switching power regulator H1, and the electric energy generated by the second-stage photovoltaic module PV2 is converted and tracked by the second-stage switching power regulator H2. Similarly, the electric energy generated by the N-th-stage photovoltaic module PVN is converted and optimized by the N-th-stage switching power regulator HN. N is a positive integer not less than 1.

[0072] See also Figure 5 In this article, the switching power supply regulator HK can be a DC switching power supply, and its specific circuit topology includes Buck circuit, Boost circuit, Buck-Boost circuit, etc. Figure 7 It is one of the typical categories of Buck-Boost circuits, and can be adaptively changed into a Buck circuit or a Boost circuit. This goal can be achieved by modifying the software of the controller 400 or directly by modifying the components and hardware circuits.

[0073] See also Figure 3 Simply pursuing the maximum power point MPP of photovoltaic modules is not the best choice, especially when photovoltaic modules are connected in series and parallel. Figure 8 As shown. Figure 8 For example, the photovoltaic module PVN does not necessarily operate continuously at the maximum power point MPP. The photovoltaic module PVN may operate at the MSP, at which time it can leave the flexible voltage or current space required for the series and parallel connection of the remaining photovoltaic modules in the network. For example, the string voltage or string current provided by the PV1-PVN string can be flexibly adjusted to meet the DC side requirements of the inverter INVT, and the photovoltaic power generation system will be more robust and stable in operation. From a system-level perspective, because the inverter INVT can perform MPPT, it allows the entire photovoltaic system to pursue greater power output. A detailed introduction will be given below.

[0074] See also Figure 2 The power tracking shown in the figure is to try to achieve the optimal working current multiplied by the optimal working voltage of the photovoltaic module from the perspective of the local end of the photovoltaic module: the power optimizer OPN tries to achieve the working current I of the photovoltaic module PVN from the perspective of the local end of the photovoltaic module PVN PVN Multiply by the operating voltage V PVNIf this product is maximized, the power optimizer OPN has successfully implemented MPP tracking for the photovoltaic module PVN.

[0075] See also Figure 2 The inverter INVT has a maximum power point tracking function, which can be used by the inverter INVT to implement maximum power point tracking for the photovoltaic modules PV1-PVN corresponding to the multi-stage power optimizers OP1-OPN in series as a whole. Note that the inverter INVT used in almost all distributed or centralized photovoltaic power stations currently has a maximum power point tracking function, which brings some disadvantages: the local maximum power point tracking of the photovoltaic modules PV1-PVN and the maximum power point tracking of the inverter INVT interfere with each other. How to guide this constraint relationship to the mutual adaptation of the power optimizer OP1-OPN and INVT to adaptively meet the MPP tracking needs of both parties is a more confusing problem.

[0076] See also Figure 2 , an explanation of the above confusion. Assume that the power optimizer OP1-OPN has achieved the working current I of the photovoltaic module PVN through maximum power tracking. PVN Multiply by the operating voltage V PVN Maximization, in the balanced state where the MPP purpose has been achieved, if the inverter INVT performs maximum power tracking again, it means that the inverter INVT will change the bus current and bus voltage to pursue the bus current I BUS Multiply by bus voltage V BUS This tracking action of the inverter INVT will break the MPP power balance that the power optimizers OP1-OPN have established. At this time, it is obviously impossible to achieve working adaptation between the power optimizers OP1-OPN and the inverter INVT and meet the tracking requirements of both.

[0077] See also Figure 2 In order to solve the above confusion, the MPPT function of the inverter INVT can be abandoned. The optimization products currently on the market have adopted this solution, such as Figure 2The principle of the MPP tracking solution shown is to perform MPP tracking only on the PV1-PVN end of the photovoltaic module, while the inverter INVT does not perform MPP tracking. The inverter simply performs the inversion of DC to AC conversion. This solution also has great inconvenience: because the existing photovoltaic inverters in photovoltaic power stations basically have MPPT function, and the photovoltaic MPPT function is standard, few inverter merchants will cancel the MPPT function of the inverter INVT to adapt to the PV1-PVN end tracking of photovoltaic modules. As a result, the power optimizer OPN configured at the photovoltaic module end is difficult to adapt to market demand. Whether it is a distributed photovoltaic power station or a centralized photovoltaic power station, it would rather give up the power optimizer OPN with MPPT than give up the MPPT function of the inverter. This is a comprehensive result based on the cost considerations of the photovoltaic power station, the final power optimization effect, and the convenience of use.

[0078] See also Figure 2 In addition, the industrial ecological chain of the photovoltaic system must also be considered. The current software architecture and hardware of the photovoltaic system are almost all based on catering to photovoltaic inverters with MPPT functions. This type of inverter INVT has adapted to the ecological chain of the standard photovoltaic system. The software and hardware system of the photovoltaic power station is also designed and laid out based on the inverter type with maximum power tracking MPPT. Abandoning the MPPT function of the photovoltaic inverter INVT is unacceptable for many existing photovoltaic power stations or newly built photovoltaic power stations. It will also lose the opportunity to optimize the power of the inverter.

[0079] See also Figure 2 Therefore, it is necessary to retain the MPPT function of the inverter INVT. However, how to achieve adaptation between the power optimizer OP1-OPN and the inverter INVT and meet the tracking requirements of both is a design difficulty of the photovoltaic system. Some solutions have designed an architecture with two MPPT coexistence, but the mainstream idea is to realize the current I of the photovoltaic module PVN in the local power optimizer OP1-OPN. PVN Multiply the voltage V PVN Maximize the current I at the busbar BUS Multiply the voltage V BUS To maximize the benefits, there are still irreconcilable difficulties in the coexistence of the two MPPTs.

[0080] See also Figure 2The difficulty of coexisting the MPP tracking of the power optimizer OP1-OPN and the MPP tracking of the inverter INVT is one of the problems that this application needs to solve. Furthermore, the photovoltaic system will inevitably face different photovoltaic module application scenarios (typically reflected in the different degrees of shading of photovoltaic modules, different numbers of photovoltaic modules in series in different strings, and the randomness of the number of strings in the parallel string relationship and other on-site factors). How to track the optimal power at the system level is a great challenge. This is another problem that this application needs to solve.

[0081] See also Figure 5 , a method for tracking a suitable power point MSP is introduced. The tracking of the suitable power point MSP is not only compatible with the inverter INVT with maximum power point tracking MPPT, but also the suitable power point MSP can smoothly cope with the different application scenarios of photovoltaic components faced by the aforementioned photovoltaic system.

[0082] See also Figure 5 , the multi-stage switching power regulators H1-HN are connected in series, and the inverter INVT performs power conversion on the output power provided by the multi-stage switching power regulators H1-HN, and performs power conversion on the sum of the output powers of the switching power regulators H1-HN. Ignoring the junction box, etc., the total power provided by the photovoltaic module array is transmitted to the inverter INVT by the DC bus, and the inverter INVT has the maximum power tracking MPPT function.

[0083] See also Figure 5 Taking the photovoltaic module PVN as an example, the switching power supply regulator HN implements DC to DC power conversion for the photovoltaic module PVN. Figure 4 As shown, during the power conversion stage implemented by the switching power supply regulator HN, the gain GN of the switching power supply regulator HN is adjusted within a range Rg_N shown in the figure, and the gain GN is allowed to track the upper limit CRobN of the range Rg_N, or the gain GN tracks the lower limit CRmpN of the range Rg_N, thereby tracking the appropriate power point MSPN of the photovoltaic module PVN.

[0084] See also Figure 4 Taking the switching power supply regulator HN and the paired photovoltaic module PVN as an example, the horizontal axis in the coordinate system represents the gain value CR of the switching power supply regulator HN, and the vertical axis represents the output power P of the photovoltaic module PVN. PVN .

[0085] See also Figure 4 , assuming that the gain of the switching power supply regulator HN during operation is GN=CRwk, the range Rg_N defined by the gain in this embodiment is marked as CRmp to CRob, CRmp≤GN≤CRob.

[0086] See also Figure 4 In an optional embodiment, the value of the lower limit CRmp can be set. However, if the gain of the power optimizer, i.e., the switching power supply regulator HN at this time, is CRmp when it has the maximum power output, it also means that the lower limit at this time is the gain value when the photovoltaic module PVN is under the maximum power point MPP state and the switching power supply regulator HN has the maximum power output, then the value of the lower limit CRmp does not need to be set. The switching power supply regulator HN does not perform maximum power tracking at this time, so the value of the lower limit CRmp at this time is unknown. Therefore, the lower limit CRmp is not a specially set value in the optional embodiment.

[0087] See also Figure 4 In an optional embodiment, the lower limit CRmp is determined by both the photovoltaic output characteristics of the photovoltaic module such as PVN itself and the output current or output voltage of the power optimizer such as the switching power supply regulator HN, and is not determined by the power optimizer such as the switching power supply regulator HN itself.

[0088] See also Figure 4 In an optional embodiment, the upper limit CRob is a pre-set specified value. In fact, for the upper limit CRob that can be set in advance, it has a fairly wide and flexible setting space. One advantage of the present application is that the upper limit CRob can be configured relatively freely, especially under the premise that the switching power supply regulator HN does not perform MPPT but instead performs MSPT tracking, the flexibility of the upper limit CRob allows searching for a suitable power point MSP of the photovoltaic module PVN within a sufficiently large range Rg_N. This is different from the maximum power point MPP search. Relatively speaking, the search for a suitable power point MSP is based on a wide gain range Rg_N, which has the advantages of convenient operation and easy adaptation to photovoltaic modules with different photovoltaic characteristics.

[0089] See also Figure 4 , as a comparison, Figure 2 Some of the limitations of traditional power optimizers are that the battery characteristics of different photovoltaic modules in the network are different. In order to adapt to the mutual cooperation of photovoltaic modules with slightly different characteristics under the same string, traditional power optimizers require certain restrictions on the battery characteristics of photovoltaic modules. The characteristics of photovoltaic modules provided by different manufacturers are different, and the characteristics of photovoltaic modules from different batches of the same manufacturer are different. Traditional power optimizers usually require restrictions on various parameters of photovoltaic modules such as voltage, current, nominal power, working environment, etc., which significantly increases the cost of photovoltaic modules that can be networked.

[0090] See also Figure 4 , as a comparison, and Figure 2Differently, the switching power supply regulator HN disclosed in the present application tracks the appropriate power point MSP of the photovoltaic module, and does not necessarily need to perform MPPT. The wide gain range Rg_N allows the power optimizer to adapt to photovoltaic modules with different battery characteristics and different parameters, allowing power tracking of various types of photovoltaic modules with poor consistency under a wide parameter range such as wide voltage, wide current and wide working environment. The traditional power optimizer is obviously difficult to adjust the appropriate power point MSP within the gain range Rg_N.

[0091] See also Figure 4 , the power gain P of the photovoltaic module PVN PVN In the -CR curve, curve 300A indicates that the output power of the photovoltaic module shows an upward trend as the gain increases, and after the maximum power point MPP is reached, the output power of the photovoltaic module represented by curve 300B shows a downward trend. Based on the gain range Rg_N, the actual gain of the switching power supply regulator HN regarded as a power optimizer is CRwk.

[0092] See also Figure 4 , CRwk operates within the range Rg_N. According to this design, it can be seen that the suitable power point MSP may fall at the maximum power point MPP or may not fall at the maximum power point MPP.

[0093] See also Figure 5 Based on solving the above-mentioned drawbacks, the power optimizer involved in the present application uses the aforementioned switching power supply regulator HN, which can also be replaced by a digital power supply (digital power). They can be used in various aspects through software programming, and have scalability and reusability to facilitate the change of some working parameters. For example, the upper or lower limit of the spatial range Rg_N of the gain is changed in some occasions when necessary, especially the upper limit.

[0094] See also Figure 5 , the switching power regulator H1 converts the electric energy captured from the corresponding photovoltaic module PV1 into the output power of the switching power regulator H1 itself. The switching power regulator H1 is used to implement DC to DC power conversion on the photovoltaic module PV1. In the power conversion stage, the gain G1 of the switching power regulator H1 is adjusted within the range Rg_1 and the range Rg_1 is CRmp1 to CRob1. Let the gain G1 track the upper limit CRob1 of the range Rg_1 or the gain G1 can also track the lower limit CRmp1 of the range Rg_1. G1 runs between CRmp1 and CRob1 to track the appropriate power point MSP1 of the photovoltaic module PV1. At this time, the actual gain G1 = CRwk1.

[0095] See also Figure 5 , as shown in the figure, U H1is the output voltage of the switching power supply regulator H1 and U P1 This is the input voltage of the switching power supply regulator H1. In Buck or Boost or Buck-Boost circuits, G1 = U H1 / U P1 The gain G1 of the switching power supply regulator H1 can be changed by changing the duty cycle of the switching power supply regulator H1.

[0096] See also Figure 5 , the switching power regulator H2 converts the electric energy captured from the corresponding photovoltaic module PV2 into the output power of the switching power regulator H2 itself. The switching power regulator H2 is used to implement DC to DC power conversion on the photovoltaic module PV2. In the power conversion stage, the gain G2 of the switching power regulator H2 is adjusted within the range Rg_2 and the range Rg_2 is CRmp2 to CRob2. Let the gain G2 track the upper limit CRob2 of the range Rg_2 or the gain G2 can also track the lower limit CRmp2 of the range Rg_2. G2 runs between CRmp2 and CRob2 to track the appropriate power point MSP2 of the photovoltaic module PV2. At this time, the actual gain G2 = CRwk2.

[0097] See also Figure 5 , as shown in the figure, U H2 is the output voltage of the switching power supply regulator H2 and U P2 This is the input voltage of the switching power supply regulator H2. In Buck or Boost or Buck-Boost circuits, G2 = U H2 / U P2 The gain G2 of the switching power supply regulator H2 can be changed by changing the duty cycle of the switching power supply regulator H2.

[0098] See also Figure 5 , the switching power regulator HN converts the electric energy captured from the corresponding photovoltaic module PVN into the output power of the switching power regulator HN itself. The switching power regulator HN is used to implement DC to DC power conversion on the photovoltaic module PVN. In the power conversion stage, the gain GN of the switching power regulator HN is adjusted within the range Rg_N and the range Rg_N is CRmpN to CRobN. The gain GN tracks the upper limit CRobN of the range Rg_N or the gain GN can also track the lower limit CRmpN of the range Rg_N. GN runs between CRmpN and CRobN to track the appropriate power point MSPN of the photovoltaic module PVN. At this time, the actual gain GN = CRwkN.

[0099] See also Figure 5 , as shown in the figure, U HN is the output voltage of the switching power supply regulator HN and U PNIt is the input voltage of the switching power supply regulator HN. In Buck or Boost or Buck-Boost circuit, GN=U HN / U PN The gain GN of the switching power supply regulator HN can be changed by changing the duty cycle of the switching power supply regulator HN.

[0100] See also Figure 5 , comparing the power P of photovoltaic modules PV1, PV2, and PVN PV1 , P PV2 , P PVN In fact, the upper and lower limits of their related gain ranges Rg_1, Rg_2, and Rg_N may be equal or different.

[0101] See also Figure 5 In an optional embodiment, it is assumed that CRmp1, CRmp2 and CRmpN are not equal to each other, for example, they can be represented by the formula CRmp1≠CRmp2≠CRmpN. If CRmp1, CRmp2 and CRmpN are equal to each other, for example, they can be represented by the formula CRmp1=CRmp2=CRmpN. CRmp1, CRmp2 and CRmpN are partially equal to each other, for example, they can be represented by the formula CRmp1=CRmp2≠CRmpN. These situations are all possible. If the remaining switching power supply regulators H3 to H(N-1) are also involved, then all CRmp1 to CRmpN will also have the aforementioned situations of being unequal to each other, being equal to each other or being partially equal to each other.

[0102] See also Figure 5 In an optional embodiment, it is assumed that CRob1, CRob2 and CRobN are not equal to each other, for example, they can be represented by the formula CRob1≠CRob2≠CRobN. If CRob1, CRob2 and CRobN are equal to each other, for example, they can be represented by the formula CRob1=CRob2=CRobN. CRob1, CRob2 and CRobN are partially equal to each other, for example, they can be represented by the formula CRob1≠CRob2=CRobN. All these situations are possible. If the remaining switching power supply regulators H3 to H(N-1) are also involved, then all CRob1 to CRobN will also have the aforementioned situations of being unequal to each other, being equal to each other or being partially equal to each other.

[0103] See also Figure 5In an optional embodiment, it is assumed that MSP1, MSP2 and MSPN are not equal to each other, for example, they can be expressed by the formula MSP1≠MSP2≠MSPN. If MSP1, MSP2 and MSPN are equal to each other, for example, they can be expressed by the formula MSP1=MSP2=MSPN. MSP1, MSP2 and MSPN are partially equal to each other, for example, they can be expressed by the formula MSP1=MSP2≠MSPN. All these situations are possible. If the remaining switching power supply regulators H3 to H(N-1) are also involved, then all MSP1 to MSPN will also have the aforementioned situations of being unequal to each other, being equal to each other or being partially equal to each other.

[0104] See also Figure 5 In an optional embodiment, it is assumed that CRwk1, CRwk2 and CRwkN are not equal to each other, for example, they can be represented by the formula CRwk1≠CRwk2≠CRwkN. If CRwk1, CRwk2 and CRwkN are equal to each other, for example, they can be represented by the formula CRwk1=CRwk2=CRwkN. CRwk1, CRwk2 and CRwkN are partially equal to each other, for example, they can be represented by the formula CRwk1≠CRwk2=CRwkN. These situations are all possible. If the remaining switching power supply regulators H3 to H(N-1) are also involved, then all CRwk1 to CRwkN will also have the aforementioned situations of being unequal to each other, being equal to each other or being partially equal to each other.

[0105] See also Figure 5 The switching power supply usually adjusts the output voltage by periodically switching on and off (ON / OFF) to control the duty cycle of the switching element. The core part of the switching power supply is power conversion. The main control methods of power conversion are divided into pulse width modulation, pulse frequency modulation, etc., and pulse width modulation scheme is commonly used. Figure 7 The switching power regulator is a voltage converter that converts DC to DC, either step-down or step-up or step-down. After the switching power regulator tracks the power of a single photovoltaic module to the appropriate power MSP, the energy of the string is transmitted to the inverter INVT for DC to AC processing. The inverter INVT is usually an inverter device equipped with maximum power tracking MPPT (for example, maximizing the product of bus voltage and bus current).

[0106] See also Figure 5 , the switching power regulators H1 to HN perform MSPT tracking. PV1 To P PVN The equal power curves and the gain adjustment ranges Rg_1 to Rg_N of the switching power regulators H1 to HN respectively illustrate the process of searching for the appropriate power points MSP1 to MSPN of the corresponding photovoltaic components PV1-PVN in the present application.

[0107] See also Figure 5 , the inverter INVT performs MPPT tracking. The inverter INVT realizes the optimal working current of the DC bus multiplied by the optimal working voltage, pursuing the bus current I BUS Multiply by bus voltage V BUS The maximum power point MPP is set to the maximum power point MPP of the string current (i.e., bus current) and the string voltage (i.e., bus voltage) of a single string. The power curve of the maximum power point tracking implemented on the DC bus is represented by S-MPPT, which is Figure 3 similar.

[0108] See also Figure 5 , if the switching power regulator HN is based on the voltage gain range Rg_N, Figure 7 The voltage sensors 111 and 113 shown collect their input voltage and output voltage respectively, and the controller 400, such as a microprocessor, calculates the actual gain of the output voltage relative to the input voltage through the voltage data collected by these voltage sensors 111 and 113. The microprocessor collects the working current of the photovoltaic module PVN through the current sensor 112, and calculates the power of the photovoltaic module PVN based on the working current and working voltage of the photovoltaic module PVN. When driving the switching power supply regulator HN, the microprocessor can adjust the actual gain of its output voltage relative to the input voltage to track the appropriate power point MSP of the photovoltaic module PVN.

[0109] See also Figure 6 In an alternative example, the gain G1' of the switching power regulator H1 is adjusted within the range Rg_1' and the range Rg_1' is CRmp_1 to CRob_1. The gain G1' tracks the upper limit CRob_1 of the range Rg_1' or the gain G1' can also track the lower limit CRmp_1 of the range Rg_1'. G1' runs between CRmp_1 and CRob_1 to track the appropriate power point MSP_1 of the photovoltaic module PV1. At this time, the actual gain G1'=CRwk_1.

[0110] See also Figure 6 , as shown in the figure, I H1 is the output current of the switching power regulator H1 and I P1 This is the input current of the switching power supply regulator H1. In the Buck or Boost or Buck-Boost circuit, G1'=I H1 / I P1 The gain G1' of the switching power supply regulator H1 can be changed by changing the duty cycle of the switching power supply regulator H1.

[0111] See also Figure 6In an alternative example, the gain G2' of the switching power regulator H2 is adjusted within the range Rg_2' and the range Rg_2' is CRmp_2 to CRob_2. The gain G2' tracks the upper limit CRob_2 of the range Rg_2' or the gain G2' can track the lower limit CRmp_2 of the range Rg_2'. G2' runs between CRmp_2 and CRob_2 to track the appropriate power point MSP_2 of the photovoltaic module PV2. At this time, the actual gain G2'=CRwk_2.

[0112] See also Figure 6 , as shown in the figure, I H2 is the output current of the switching power regulator H2 and I P2 This is the input current of the switching power supply regulator H2. In the Buck or Boost or Buck-Boost circuit, G2'=I H2 / I P2 The gain G2' of the switching power supply regulator H2 can be changed by changing the duty cycle of the switching power supply regulator H2.

[0113] See also Figure 6 In an alternative example, the gain GN' of the switching power regulator HN is adjusted within the range Rg_N' and the range Rg_N' is CRmp_N to CRob_N. The gain GN' tracks the upper limit CRob_N of the range Rg_N' or the gain GN' can track the lower limit CRmp_N of the range Rg_N', and GN' runs between CRmp_N and CRob_N to track the appropriate power point MSP_N of the photovoltaic module PVN. At this time, the actual gain GN'=CRwk_N.

[0114] See also Figure 6 , as shown in the figure, I HN is the output current of the switching power regulator HN and I PN This is the input current of the switching power supply regulator HN. In the Buck or Boost or Buck-Boost circuit, GN'=I HN / I PN The gain GN' of the switching power supply regulator HN can be changed by changing the duty cycle of the switching power supply regulator HN.

[0115] See also Figure 6 , comparing the power P of photovoltaic modules PV1, PV2, and PVN PV1 , P PV2 , P PVN The upper and lower limits of their related gain ranges Rg_1', Rg_2', and Rg_N' may be equal or different. Figure 5The characteristics of the upper and lower limits of the gain range (the relationship between CRmp_1 and CRmp_N and the relationship between CRob_1 and CRob_N) are also applicable to this embodiment. Figure 6 As for the appropriate power points MSP_1 to MSP_N, Figure 5 The characteristics of a series of suitable power points (the relationship between MSP_1 to MSP_N) are also applicable to this embodiment, such as Figure 6 shown.

[0116] See also Figure 6 , if the switching power regulator HN is based on the current gain range Rg_N', Figure 7 The current sensors 112 and 114 shown collect their input current and output current respectively, and the controller 400, such as a microprocessor, calculates the actual gain of the output current relative to the input current through the current data collected by these current sensors 111 and 113. The microprocessor collects the working voltage of the photovoltaic module PVN through the voltage sensor 111, and calculates the power of the photovoltaic module PVN according to the working current and working voltage of the photovoltaic module PVN. When driving the switching power supply regulator HN, the microprocessor can adjust the actual gain of its output current relative to the input current to track the appropriate power point MSP_N of the photovoltaic module PVN.

[0117] See also Figure 5 , the switching power supply regulator H1-HN needs to achieve power tracking of the corresponding photovoltaic components PV1-PVN but no longer simply track MPPT (that is, maximize the product of the output current and output voltage of the photovoltaic components). As mentioned above, the power optimization pursued by the switching power supply regulator H1-HN may not be the maximum power point of the corresponding photovoltaic components PV1-PVN but the appropriate power optimization, provided that it can achieve a high degree of adaptation with the MPPT of the inverter INVT. The appropriate power may be the maximum power point of the photovoltaic components PV1-PVN, or it may not be their maximum power point. The appropriate power point takes into account the coordination and cooperation with the MPPT of the inverter INVT.

[0118] See also Figure 5 The MSPT of the switching power supply regulator H1-HN and the MPPT of the inverter INVT work together to achieve a harmonious coexistence, advocating the cooperation between the MSPT and the MPPT. This design is based on the aforementioned problems that the MPPT of the power optimizer OP1-OPN and the MPPT of the inverter INVT may hinder and interfere with each other, causing the photovoltaic components that have been parked at the maximum power point to deviate from the maximum power point, or are in a see-saw state of entering the maximum point and escaping from the maximum point. This application can just solve such problems.

[0119] See also Figure 7The switching power regulator H1-HN includes a DC / DC converter. The topology shown in the figure is only an optional example, but the switching power regulator H1-HN is not limited to a specific type. The switching power regulator preferably has a boost circuit and a buck circuit at the same time. The photovoltaic module PVK uses the switching power regulator HK (K is any number from 1 to N) to generate the desired output voltage / output current while performing the desired MSP tracking.

[0120] See also Figure 7 The first input terminal IN1 of the input side of the switching power supply regulator HK is coupled to the positive terminal of the photovoltaic module PVK and the second input terminal IN2 is coupled to the negative terminal of the photovoltaic module PVK. The switching power supply regulator HK provides an output voltage and an output power between the first output terminal NO1 and the second output terminal NO2 on the output side. In addition, the input capacitor C1 can be set to be connected between the first input terminal IN1 and the second input terminal IN2, and the output capacitor C2 can be set to be connected between the first output terminal NO1 and the second output terminal NO2.

[0121] See also Figure 7 The switching power supply regulator HK performs DC / DC voltage conversion on the direct current of the photovoltaic module PVK and performs MSP tracking calculation synchronously. In the topological structure, the power switch S1 and the power switch S2 of the buck conversion circuit module in the switching power supply regulator HK are connected in series between the first input terminal IN1 and the second input terminal IN2, and the power switch S3 and the power switch S4 of the boost conversion circuit of the switching power supply regulator HK are connected in series between the first output terminal NO1 and the second output terminal NO2. The switching power supply regulator HK adopts a switching power supply that can step up and step down. The buck conversion circuit and the boost conversion circuit both share the same inductor device L.

[0122] See also Figure 7 , the power switch S1 and the power switch S2 are both connected to the first interconnection node X1, and the power switch S3 and the power switch S4 in the boost conversion circuit module are both connected to the second interconnection node X2. An inductor element L is set between the first interconnection node X1 where the front power switches S1-S2 are connected and the second interconnection node X2 where the rear power switches S3-S4 are connected in the buck-boost circuit topology. The second output terminal NO2 and the second input terminal IN2 can be directly coupled together or their potentials can be set to be substantially the same.

[0123] See also Figure 7 The controller 400 configured in the switching power supply regulator HK, such as the pulse width modulator of the microprocessor MCU, sends several pulse modulation signals D1-D4 to drive the power switches S1-S4. The controller 400 can use a driver with stronger driving capability to amplify the driving capability of the signals D1-D4 and then drive the power switches S1-S4.

[0124] See also Figure 7 When the switching power supply regulators are connected in series, the first output terminal NO1 of the switching power supply regulator HK can be coupled to the second output terminal NO2 of the adjacent previous switching power supply regulator H(K-1).

[0125] See also Figure 7 When the switching power supply regulators are connected in series, the second output terminal NO2 of the switching power supply regulator HK can be coupled to the first output terminal NO1 of the adjacent subsequent switching power supply regulator H(K+1).

[0126] See also Figure 7 The power switches S1-S2 together constitute a buck single arm of the buck circuit. The D1 and D2 signals provided by the pulse width modulator of the controller 400 can be used to drive the complementary switches S1 and S2 of the buck circuit respectively. S1-S2 both switch at high frequency but they are not allowed to be turned on at the same time. The duty cycle of the pulse modulation signal for the buck circuit refers to the duty cycle of the power switch S1, and the power switch S2 is a synchronous freewheeling switch.

[0127] See also Figure 7 If only the Buck circuit is retained, S3 and S4 can be discarded, such as replacing S4 with a wire or directly deleting S3 in the circuit topology. Alternatively, the pulse modulation signal D4 of the controller 400 is required to continuously turn on S4, but the pulse modulation signal D3 needs to continuously control S3 to turn it off. The power switch S2 can also be replaced by a freewheeling diode.

[0128] See also Figure 7 The power switches S3-S4 together constitute a single boost arm of the boost circuit. The D3 and D4 signals provided by the pulse width modulator of the controller 400 can be used to drive the complementary switches S3 and S4 of the boost circuit respectively. S3-S4 both switch at high frequency but they are not allowed to be turned on at the same time. The duty cycle of the pulse modulation signal for the boost circuit refers to the duty cycle of the power switch S3, and the power switch S4 is a synchronous freewheeling switch.

[0129] See also Figure 7 If only the Boost circuit is retained, S1 and S2 can be discarded, such as replacing S1 with a wire and directly deleting S2 in the circuit topology. Alternatively, the pulse modulation signal D1 of the controller 400 is required to continuously turn on S1, but the pulse modulation signal D2 needs to continuously control S2 to turn it off. The power switch S4 can also be replaced by a freewheeling diode.

[0130] See also Figure 7In summary, the topology of the switching power supply regulator HK is not limited to any specific restrictions. It can be the buck-boost circuit shown in the figure, or it can be modified to only retain the Buck circuit or the Boost circuit. The Buck circuit has many variations in the industry, and the Boost circuit also has many variations in the industry. Other voltage converters that replace the circuit topology shown in the figure typically include the CUK circuit and the inverse SEPIC circuit.

[0131] See also Figure 7 , the switching power supply regulator HK is equipped with a controller 400, and the MSP tracking can be implemented by the pulse width modulation signal output by the controller for driving the switching power supply. The controller and the peripheral hardware configured therein can collect various target parameters of photovoltaic components such as PVK or the switching power supply regulator HK, which is equivalent to a data collector. Capturing these target parameter data is helpful to realize MSP tracking. In an optional example, the peripheral hardware can collect a series of relevant specified target parameter information such as the voltage, current and power of the photovoltaic component as well as the temperature and power generation: the voltage parameter is collected by the voltage sensor 111, and the current parameter is collected by the current sensor 112. The temperature parameter can be collected by the peripheral hardware such as the temperature sensor and the light radiation intensity is collected by the light sensor. In addition, the output voltage of the switching power supply regulator HK is detected by the voltage sensor 113, and the output current of the switching power supply regulator HK is detected by the current sensor 114.

[0132] See also Figure 7 Target parameters related to the photovoltaic module PVK, such as the working voltage and working current of the photovoltaic module, are transmitted to the controller 400 by the corresponding voltage sensor 111 and current sensor 112. The working voltage and working current are essentially the input voltage and input current of the switching power supply regulator HK.

[0133] See also Figure 7 , target parameters related to the switching power supply regulator HK, such as its output voltage and output current, are transmitted to the controller 400 by the corresponding voltage sensor 113 and current sensor 114 respectively.

[0134] See also Figure 7 The controller 400 is selected from a field programmable gate array, a processor, a state machine, a software-driven control device or a complex programmable logic device, a semi-custom ASIC, a microprocessor, a logic circuit, and a single-chip microcomputer.

[0135] See also Figure 7 The Buck and its variant forms, Boost and its variant forms, Buck-Boost and its variant forms, or alternative CUK circuits and SEPIC circuits in the figure can be applied to switching power supply regulators or to digital power supplies or equivalent power conversion devices. They are controlled by the controller 400 and serve as components of the power optimizer.

[0136] See also Figure 8 In an optional embodiment, the switching power regulators are connected in series. As shown in the figure, the switching power regulators H1-HK can be connected in series, the switching power regulators H1-HN can be connected in series, or more other groups of switching power regulators not shown can be connected in series, and different groups of switching power regulators are connected in parallel. For example, the series connection structure of the switching power regulator H1-HK is connected in parallel with the series connection structure of the switching power regulator H1-HN. If there are other series connection structures of the switching power regulators, then the different series connection structures are all connected in parallel.

[0137] See also Figure 8 , multiple battery groups are connected in series and parallel between busbars LA and LB. If it is defined that the multi-stage switching power regulator H1-HN forms a link, multiple links are allowed to be connected in parallel between busbars LA and LB. For example, if the switching power regulator H1-HK forms another link, it is also connected between busbars LA and LB.

[0138] See also Figure 8 In an optional embodiment, a plurality of photovoltaic modules PV1-PVN corresponding to a set of series-connected switching power regulators H1-HN can be regarded as a string (PV-string1), and a plurality of photovoltaic modules PV1-PVK corresponding to the switching power regulator H1-HK can be regarded as another string (PV-string2). More strings are not shown in the figure.

[0139] See also Figure 8 , this parallel connection of multiple strings will bring some disadvantages in power tracking: if the number of series connections N and K of different components are not equal, that is, facing different PV component application scenarios as mentioned above, under this condition, the MPPT of the inverter INVT can guide the string (PV1-PVN) to work at the maximum power point MPP, but it may not be able to make the string (PV1-PVK) also work at the maximum power point MPP. In fact, the total power that a larger number of PV components can provide is usually much greater than that of a smaller number of PV components. K is a positive integer not less than 1.

[0140] See also Figure 8 The tricky problem is that each switching power regulator H1-HN corresponding to the string PV-string1, such as HN, tries to make the corresponding photovoltaic module, such as PVN, reach the appropriate power MSP. In this working state, the output voltage of each switching power regulator H1-HN generates a string voltage U H1 +U H2 +…U HN .

[0141] See also Figure 8In contrast, each switching power regulator H1-HK corresponding to the string PV-string2, such as HK, attempts to make the corresponding photovoltaic module, such as PVK, reach the appropriate power MSP. In this working state, the output voltages of the switching power regulators H1-HK generate the string voltage U H1 +U H2 +…U HK .

[0142] See also Figure 8 If no measures are taken, U H1 +U H2 +…U HN and U H1 +U H2 +…U HK However, for the photovoltaic inverter INVT, the maximum power point of the DC bus corresponds to only one bus voltage value, so there is a matching problem between different strings, which causes the photovoltaic inverter INVT to be confused in executing MPPT. At this time, the relevant advantages of this application are obvious. As long as the actual gain values ​​of different strings are slightly modified, the string voltages generated by different strings can be infinitely close to meet the requirements of the inverter INVT for string voltage when executing MPPT.

[0143] See also Figure 8 In an optional embodiment, assuming that N>K is satisfied, the gains G1-GN of the switching power regulators H1-HN corresponding to the string PV-string1 are all adjustable within their own ranges Rg_1 to Rg_N. The adjustable gain means that the output voltage of the switching power regulator is floating. H1 or U H2 or U HN etc. are all adjustable, so the sum of their superimposed string voltage U H1 +U H2 +…U HN Please note that the gain of the switching power regulator is adjusted within its own range and does not affect the appropriate power point MSP1-MSPN of the tracking photovoltaic module PV1-PVN.

[0144] See also Figure 8 In an optional embodiment, N>K is still satisfied, and the gains G1-GK of the switching power regulator H1-HK corresponding to the string PV-string2 are adjustable within their own range Rg_1 to Rg_K. The adjustable gain means that the output voltage of the switching power regulator is floating. H1 or U H2 or U HK etc. are all adjustable, so the sum of their superimposed string voltage U H1 +U H2 +…UHK Similarly, the gain of the switching power supply regulator is adjusted within its own range and does not affect the appropriate power point MSP1-MSPK of the tracking photovoltaic module PV1-PVK.

[0145] See also Figure 8 , due to the above measures, U H1 +U H2 +…U HN and U H1 +U H2 +…U HK The two can be easily equal or close. The gains of different switching power regulators HN can be adjusted to be the same or different, which is extremely helpful for making the string voltages of different strings equal or close when the inverter INVT performs power tracking. There is no doubt that this is one of the manifestations of the mutual coordination and adaptation between the MSPT tracking function of the switching power regulator H1-HN and the MPPT tracking function of the inverter INVT.

[0146] See also Figure 6 In an optional embodiment, a single string supplies power to the inverter INVT. The inverter converts the string current of the single string, i.e., I BUS And the string voltage V BUS Set at its MPP.

[0147] See also Figure 8 In an optional embodiment, multiple strings supply power to the inverter INVT. The inverter converts the sum of the string currents of all strings, i.e., the bus current I BUS And the string voltage is the bus voltage V BUS In this example, multiple strings are connected in parallel, and the bus current is the sum of the string currents or string-level currents of the multiple strings shown in the figure (for example, in the case of two strings, the bus current is the string current I N Add string current I K ), the bus voltage is the same string voltage or string-level voltage for each of the multiple strings shown in the figure.

[0148] See also Figure 8 In an optional embodiment, multiple strings supply power to the inverter INVT. As shown in the figure, the inverter converts the string current of a single string PV-string1, i.e., I N And the string voltage V BUS The inverter also sets the string current of a single string PV-string2, that is, I K And the string voltage V BUS In the parallel relationship of the string, the output current of the switching power supply regulators H1-HN connected in series is the string current I NThe output currents of the switching power regulators H1-HK connected in series are all string currents I K .

[0149] See also Figure 8 , the operating gains of the switching power regulators corresponding to the strings (PV-string1, PV-string2) with different numbers of PV modules can be set to be different. N and K are different. The operating gain value of the switching power regulator H1-HN is set to be different from the gain value of the switching power regulator H1-HK, and the gains of different switching power regulators in the switching power regulator H1-HN can also be set to be the same, and at the same time, the gains of different switching power regulators in the switching power regulator H1-HK can also be set to be the same.

[0150] See also Figure 8 In an optional embodiment, the operating gain value of the switching power supply regulator H1-HK corresponding to the string with a small number of photovoltaic components (PV-string2) is larger than the gain value of the switching power supply regulator H1-HN corresponding to the string with a large number of photovoltaic components (PV-string1).

[0151] See also Figure 8 In an optional embodiment, the goal of the MSP tracking mentioned in this application is to quickly respond to changes in photovoltaic module power, so that distributed or centralized photovoltaic power stations have high photoelectric conversion efficiency, power optimization, compatibility with existing photovoltaic systems, and stable operation. MSP tracking is fully compatible with the MPPT architecture of the photovoltaic inverter INVT of existing distributed power stations or centralized power stations. Under this premise, the multi-stage switching power supply regulator or power optimizer is completely coupled with the MPPT algorithm of the external inverter INVT. The local power tracking of the photovoltaic module and the power tracking of the remote inverter will not interfere with each other. Even the local MSP power tracking of the photovoltaic module can cooperate with the maximum power tracking algorithm of the inverter to achieve the overall optimal power optimization effect.

[0152] See also Figure 5 The working mechanism of the traditional power optimizer is different from that of the power optimizer in this paper. The former pursues the working current I of the photovoltaic module PVN at the photovoltaic module end. PVN Multiply by the operating voltage V PVN The latter is to pursue the appropriate power processing of the photovoltaic module PVN at the photovoltaic module end (I PVN Multiply by V PVNIt may or may not be the maximum. For example, if the gain GN=CRwkN falls exactly at CRmpN, then MSP is the maximum power point and coincides with MPP. Otherwise, MSP and MPP do not coincide. The switching power supply regulator HN usually does not know whether it has the maximum power output or whether the photovoltaic module PVN is at the MPP, because it does not calculate I PVN ×V PVN This is a significant difference from traditional power optimizers.

[0153] See also Figure 8 , based on the above, Figure 2 There is a lack of sufficient layout flexibility between different strings networked by traditional power optimizers. It is usually required that the number of PV modules used in different strings should not differ too much, for example, the N and K of the two networked strings PV-string1 and PV-string2 should be the same or similar. This requirement is very unrealistic or too harsh in many photovoltaic system applications. Furthermore, Figure 2 Traditional power optimizers have a specific MPPT power tracking function that pursues the maximum power point, which limits the voltage floating range of the power optimizer. Otherwise, at least part of the photovoltaic modules will drift away from the MPP when catering to string and parallel connection.

[0154] See also Figure 8 , based on the above, Figure 5 The power optimizer in this article has sufficient layout flexibility between different strings of the network. For example, the number of photovoltaic modules used in different strings is allowed to be designed differently, such as allowing the N and K of the two networked strings PV-string1 and PV-string2 to be freely and flexibly adjusted. For example, in an optional embodiment, it is assumed that the string PV-string2 uses a small number of photovoltaic modules, K<N. At this time, some or all of the switching power supplies in the switching power supply regulator H1-HK only need to fine-tune their operating gain values. Under this condition, the power optimizer pursuing power tracking has a larger voltage floating range, because the adjustment of the operating gain value is equivalent to the flexible expansion range of the input and output voltages of the switching power supply regulator H1-HK. It is worth noting that this example does not allow the photovoltaic module to drift away from its appropriate power position when catering to the parallel connection of the strings. It is easy to understand that whether the number of photovoltaic modules used in different strings in this example is the same or different, it does not affect the tracking of the appropriate power MSP position of the photovoltaic module.

[0155] See also Figure 8Based on the above, the advantages of the switching power supply regulator in this article include: when strings of different lengths are connected in parallel, parallel matching can be achieved by adjusting the operating gain value within the gain range, which is convenient for string parallel connection. Power tracking and the free and flexible change of the output voltage and input voltage range of the switching power supply regulator coexist at the same time. However, when the traditional power optimizer changes the output voltage and input voltage in the maximum power balance state, it may push the photovoltaic module from the original maximum power position MPP to other power positions extremely far away from the MPP point.

[0156] See also Figure 8 Based on the above, the intuitive performance of appropriate power tracking is also reflected in: when the switching power regulators are connected in series, any switching power regulator HN can flexibly configure the output voltage and input voltage, and the cascade voltage U output by the switching power regulators H1-HN H1 +U H2 +…U HN There will be considerable flexibility, and the free expansion of the string voltage will not affect the MSP power optimization operation of the switching power supply regulator H1-HN. Traditional power optimizers cannot freely configure the adjustment range of the string voltage in a large range. Generally speaking, the way to change the string voltage is either to increase the number of photovoltaic modules in the string and increase the number of paired power optimizers, or to reduce the number of photovoltaic modules in the string and reduce the number of paired power optimizers. This requires on-site construction in the photovoltaic power station, involving demolition and construction.

[0157] See also Figure 8 , the inverter INVT periodically and frequently adjusts the bus voltage V BUS and bus current I BUS When tracking the maximum bus power, Figure 2 The output voltage and output current of the conventional power optimizer shown are forced to change to cater to the bus voltage V BUS and bus current I BUS The dynamic changes of the bus voltage and bus current make the power optimizer drift the photovoltaic modules PV1-PVN from their maximum power point to other power point positions suitable for tracking the bus voltage and bus current.

[0158] See also Figure 8 In other words, the intuitive performance of appropriate power tracking is reflected in the frequent adjustment of the bus voltage V by the inverter INVT. BUS and bus current I BUS When tracking the busbar MPPT, the PV modules PV1-PVN are pushed to their respective maximum power points. This is the essence of MPPT tracking. At the same time, the gain of the switching power regulator HN is adjusted within the set range. Considering that the inverter INVT adjusts V BUS and I BUSThe action required by MPP tracking and the gain change of the switching power supply regulator HN just meet the requirements of regulating V BUS and I BUS Therefore, the power tracking MPPT of the inverter and the power optimization of the voltage converter HN will naturally not interfere with each other. Instead, the two will cooperate and promote each other to achieve a win-win effect and improve the power conversion rate. Undoubtedly, this is another manifestation of the coordination and adaptation between the appropriate power point tracking MSPT of the switching power supply regulator HN and the MPPT of the inverter INVT.

[0159] See also Figure 8 , the switching power regulators H1-HN are connected in series: the second output terminal of the previous switching power regulator is coupled to the first output terminal of the adjacent next switching power regulator. The second output terminal of the first switching power regulator H1 is connected to the first output terminal of the second switching power regulator H2, and the second output terminal of the second switching power regulator H2 is connected to the first output terminal of the third switching power regulator H3. The second output terminal of the N-1th switching power regulator H(N-1) is connected to the first output terminal of the Nth switching power regulator HN. Therefore, it can also be considered that the series voltage provided by the series-connected switching power regulators H1-HN is equal to the superposition value of their respective output voltages. The total series voltage generated by the voltage converters H1-HN can be provided between the bus LA coupled to the first output terminal of the first-stage switching power regulator H1 and the bus LB coupled to the second output terminal of the Nth-stage voltage converter HN.

[0160] See also Figure 7 In an optional embodiment, in combination with Figure 5 , the respective ranges of the gain ranges Rg_1 to Rg_N can be adjusted, for example, by changing the respective upper limits CRob1 to CRobN of the ranges Rg_1 to Rg_N. In an optional embodiment, the respective lower limits of the ranges Rg_1 to Rg_N do not need to be adjusted or set. The controller 400 drives the switching power supply regulator to perform voltage conversion or current conversion. The controller 400 matched with the switching power supply regulator HN can adjust the gain GN by changing the duty cycle of the switching power supply regulator HN, so that the gain GN is adjustable within Rg_N. The upper limit value mentioned here can be programmed and rewritten in the controller 400. The controller 400 usually has a communication function, so the upper limit value and other parameters can be programmed through communication.

[0161] See also Figure 8In an optional embodiment, the switching power supply regulator HN performs DC to DC power conversion on the photovoltaic module PVN. In the power conversion stage, the gain GN of the switching power supply regulator HN is adjusted within the range Rg_N and the appropriate power point or the most appropriate power point of the photovoltaic module PVN is tracked by allowing the gain GN to track the upper limit or the lower limit of the range Rg_N. For example, the power tracking of the appropriate power SP of the photovoltaic module PVN is implemented, and the upper and lower limit tracking schemes are as described below. For example, by tracking SP = pow / (Y+abs(CRobN-CRwkN)×r1), the scheme of tracking the voltage-based gain GN=CRwkN to the upper limit CRobN can achieve the purpose of achieving MSP. The microprocessor can perform tracking operations on SP. For example, by tracking SP = pow / (Y+abs(CRob_N-CRwk_N)×r2), the scheme of tracking the current-based gain GN'=CRwk_N to the upper limit CRob_N can achieve the purpose of MSP. The symbol abs in the formula represents the absolute value, and pow represents the power of the photovoltaic module PVN. PVN *V PVN The coefficients r1 and r2 appearing respectively have different values, and Y, which can be adjusted as needed, is a non-zero constant. r1 and r2 represent preset coefficient values ​​that can be set in advance as needed and can be adjusted at any time.

[0162] See also Figure 8 In an optional embodiment, the power SP tracking is still implemented for the photovoltaic module PVN, and the upper and lower limit tracking scheme is as follows. For example, SP = pow / (T+(CRobN-CRwkN) 2 ×e1) to track the voltage-based gain GN = CRwkN to the upper limit CRobN, which can achieve the purpose of MSP. The microprocessor can perform tracking operations on SP. For example, SP = pow / (T+(CRob_N-CRwk_N) 2 ×e2) tracking, the current-based gain GN'=CRwk_N is tracked to the upper limit value CRob_N to achieve the purpose of MSP. The values ​​of the coefficients e1 and e2 that appear respectively are different, and the size of T that can be adjusted as needed is a non-zero constant. e1 and e2 represent preset coefficient values ​​that can be set in advance as needed and can be adjusted at any time.

[0163] See also Figure 8 In an optional embodiment, the power SP tracking is still implemented for the photovoltaic module PVN, and the upper and lower limit tracking scheme is as follows. For example, SP = pow / abs ((CRobN-CRwkN) P×r3-X) to track the voltage-based gain GN=CRwkN to the upper limit CRobN, which can achieve the purpose of MSP. The microprocessor can perform tracking operations on SP. SP=pow / abs((CRob_N-CRwk_N) P ×r4-X) tracking, the current-based gain GN'=CRwk_N is tracked to the upper limit value CRob_N to achieve the purpose of MSP. The values ​​of the coefficients r3 and r4 that appear respectively are different. The non-zero even superscript P represents the power symbol or several powers. r3 and r4 represent preset coefficient values ​​that can be set in advance as needed and can be adjusted at any time. X is a non-zero constant whose size can be adjusted as needed.

[0164] See also Figure 8 In an optional embodiment, the power SP tracking is still implemented for the photovoltaic module PVN, and the upper and lower limit tracking scheme is as follows. For example, SP = pow / (J+(CRobN-CRwkN) P ×r5) to track the voltage-based gain GN = CRwkN to the upper limit CRobN, which can achieve the purpose of MSP. The microprocessor can perform tracking operations on SP. For example, SP = pow / (J + (CRob_N - CRwk_N) P ×r6) to track the current-based gain GN'=CRwk_N to the upper limit value CRob_N to achieve the purpose of MSP. The values ​​of the coefficients r5 and r6 that appear respectively are different. The non-zero even superscript P represents the power symbol or several powers. r5 and r6 represent preset coefficient values ​​that can be set in advance as needed and can be adjusted at any time. J is a non-zero constant whose size can be adjusted as needed. In this application, the appropriate power SP can still be tracked to its maximum value using methods such as perturbation observation method and incremental admittance. When the gain tracks the upper limit, the difference between the gain and the upper limit needs to be reduced. When the gain tracks the lower limit, the difference between the gain and the lower limit needs to be reduced.

[0165] See also Figure 8 In an optional embodiment, the previous working gain will have a previous SP value. If the previous working gain is increased to a subsequent working gain, the subsequent working gain will have a subsequent SP value. Assuming that the traditional perturbation observation method is used and the subsequent SP value is increased compared to the previous SP value, the working gain continues to be increased. Otherwise, the perturbation direction is changed, such as reducing the working gain of the switching power supply regulator. This process is repeated until the appropriate power SP is maximized.

[0166] See also Figure 8At present, in distributed or centralized photovoltaic power stations, the problem worthy of attention is that shadows cause mismatches between many photovoltaic modules. The problem also lies in the fact that the battery output characteristics of photovoltaic modules are reflected in the close relationship between output voltage and output current and external factors such as light intensity and ambient temperature. The uncertainty of external environmental factors causes the maximum output power and the corresponding voltage of the maximum power point to change with the changes of external factors.

[0167] See also Figure 8 The above text explains how to adjust the gain GN of the switching power supply regulator HN within the range Rg_N and discloses various embodiments for allowing the gain GN to track the upper limit CRobN of the range Rg_N, and the various embodiments given prove that the schemes for the gain GN to track the upper limit CRobN are diverse. Although the lower limit CRmpN can also be actively set similar to the upper limit CRobN, a better solution is to use the maximum power tracking of the inverter INVT to allow the gain GN to approach the lower limit CRmpN by itself. After all, there are N photovoltaic modules, and their corresponding switching power supply regulators are approximately N. Trying to find the lower limits CRmp1 to CRmpN corresponding to each photovoltaic module will be a time-consuming and laborious task. Furthermore, the lower limits CRmp1 to CRmpN are related to the battery characteristics of the photovoltaic modules, and they change with the changes in external factors of the photovoltaic modules (light intensity, ambient temperature, degree of shading, etc.).

[0168] See also Figure 8 In an optional embodiment, a plurality of switching power regulators H1-HN are connected in series to form a first link or branch. Each switching power regulator such as HN is used to track the appropriate power point MSPN of the photovoltaic module PVN corresponding thereto. In an optional embodiment, the scale of the relevant range Rg_N of the gain GN of the switching power regulator such as HN is compressed (or the size of Rg_N is compressed) by tracking the maximum power point MPP of the first link.

[0169] See also Figure 8 In another embodiment, a plurality of switching power regulators H1-HK are connected in series to form a second link or branch. Each switching power regulator such as HK is used to track the appropriate power point MSPK of the photovoltaic module PVK corresponding thereto. In an optional embodiment, the scale of the relevant range Rg_K of the gain GK of the switching power regulator such as HK is compressed (or the size of Rg_K is compressed) by tracking the maximum power point MPP of the second link.

[0170] See also Figure 6In an optional embodiment, the way to compress the scale of the range Rg_N includes: reducing the gap between the upper limit and the lower limit of this range. For example, raising the lower limit or lowering the upper limit, but the lower limit is usually variable. Therefore, the best way is to use a power conversion device with an MPPT function to track the maximum power point MPP of the first link after the upper limit CRobN of the given range Rg_N. In addition to the inverter INVT, the power conversion device can also use other DC converters with MPPT functions. Taking the inverter INVT as an example, when it tracks the maximum power point MPP of the first link, it will force the lower limit CRmpN and the upper limit CRobN to close together. In the optional example, this scheme is equivalent to compressing or reducing the scale of the range Rg_N. In the optional example, this scheme is also equivalent to adjusting the gain GN=CRwkN of the switching power supply regulator HN within the range Rg_N. After all, it is advocated to let the gain GN track the upper limit CRobN or the lower limit CRmpN of the range to track the MSPN of the photovoltaic module PVN.

[0171] See also Figure 8 In an optional embodiment, the method of compressing a range scale includes: making the upper limit and the lower limit coincide with each other, that is, making the upper limit equal to or approximately equal to the lower limit. Figure 8 In the example, it is assumed that some photovoltaic modules such as PVN in the string PV-string1 are shaded, and other photovoltaic modules such as PV1-PV2 are not shaded. The maximum power point MPP of the first link is tracked to compress the scale from Rg_1 to Rg_N: the result makes CRob1 equal to or approximately equal to CRmp1 and also makes CRob2 equal to or approximately equal to CRmp2, but CRobN and CRmpN do not overlap. According to this assumption, it can be learned that G1 is equal to or approximately equal to CRob1 or CRmp1, G2 is equal to or approximately equal to CRob2 or CRmp2, but GN=CRwkN does not successfully fall at CRmpN in the case of shade. This scheme is a compromise. Under this assumption, the appropriate power point MSP1 of the photovoltaic module PV1 is the maximum power point of the photovoltaic module PV1, and the appropriate power point MSP2 of the photovoltaic module PV2 is also the maximum power point of the photovoltaic module PV2. In contrast, the appropriate power point MSPN of the shaded photovoltaic module PVN is not the maximum power point of the photovoltaic module PVN, but the power of the photovoltaic system is optimal. During this period, the gain G1 can be directed toward the lower limit CRmp1, G2 can be directed toward CRmp1, and GN can be directed toward CRmpN.

[0172] See also Figure 8In another embodiment, a parallel string is taken as an example. Assuming that some photovoltaic modules such as PV1 in the string PV-string2 are shaded, and other photovoltaic modules such as PV2 / PVK are not shaded, the maximum power point MPP of the second link is tracked to compress the scale of Rg_1 to Rg_K: the result makes CRob2 equal to or approximately equal to CRmp2 and also makes CRobK equal to or approximately equal to CRmpK, but CRob1 and CRmp1 do not overlap. According to this assumption, it can be learned that G2 is equal to or approximately equal to CRob2 or CRmp2, GK is equal to or approximately equal to CRobK or CRmpK, and G1=CRwk1 in the case of shade does not successfully fall at CRmp1. This solution is also a compromise. Under this assumption, the appropriate power point MSP2 of the photovoltaic module PV2 is the maximum power point of the photovoltaic module PV2, and the appropriate power point MSPK of the photovoltaic module PVK is also the maximum power point of the photovoltaic module PVK. In contrast, the appropriate power point MSP1 of the shaded photovoltaic module PV1 is not the maximum power point of the photovoltaic module PV1, but the power of the photovoltaic system is optimal.

[0173] See also Figure 8 In an optional embodiment, the lower limit, such as CRmpK, is the gain when the photovoltaic module PVK is at the maximum power point and the switching power regulator HK has the maximum power output. For example, a plurality of switching power regulators H1-HK are connected in series into a link, and the method of forcing the gains G1-GK to track the respective lower limits includes: by tracking the maximum power point MPP of the link to approach the gains G1-GK to the respective corresponding lower limits CRmp1-CRmpK.

[0174] See also Figure 8 In an optional embodiment, the situation where the lower limit, such as CRmpK, and the upper limit, such as CRobK, coincide with each other includes a situation where the photovoltaic component PVK is not blocked.

[0175] See also Figure 8 In an optional embodiment, the situation where the lower limit, such as CRmpN, and the upper limit, such as CRobN, do not overlap includes a situation where the photovoltaic module PVN is blocked.

[0176] See also Figure 8, the power optimizer can use a switching power supply regulator, and its gain during operation is CRwk, and the CRwk of the power optimizer runs between CRmp and CRob. When the power optimizer is actually running, the power optimizer does not actually know what CRmp is because MPPT is not performed. There are many ways to implement the adjustment and tracking method of CRwk of the power optimizer. According to the tracking embodiment described above, different algorithms or algorithm parameter adjustments can make CRwk closer to CRmp or make CRwk closer to CRob. Only when CRmp=CRob, the CRwk of the power optimizer is CRmp, and the power optimizer is operating at the maximum power point. At other times, the power optimizer is likely not operating at the maximum power point.

[0177] See also Figure 8 , the external characteristics of the power optimizer, or from the perspective of the inverter INVT or other external power conversion devices with MPPT, the power characteristics of the photovoltaic system with a power optimizer are as follows: when the gain of the switching power supply regulator as the power optimizer reaches CRob, the total power of the photovoltaic system tends to the maximum.

[0178] See also Figure 8 If all PV modules, such as PV1-PVN, have the same power characteristics and are not blocked, the inverter or other external power conversion equipment with integrated MPPT function will continuously adjust the current or voltage, such as adjusting the bus current and bus voltage or adjusting the string current and string voltage, so that the gain of each power optimizer approaches CRob and can eventually work at CRob. At this time, for the power optimizer, its CRmp is CRob, and the entire PV system will work at the maximum operating point.

[0179] See also Figure 8 , when the power characteristics of each photovoltaic module in the photovoltaic system are inconsistent, for example, some photovoltaic modules are blocked while others are not blocked, then the photovoltaic system may not work at the maximum power point. In actual use, the power optimizer corresponding to the unblocked photovoltaic modules works almost at or near CRmp, and the power optimizer corresponding to the blocked photovoltaic modules does not work at the maximum power point. This is a characteristic of the present application method, but it actually has little impact in actual applications, because the photovoltaic system can still obtain the best power under the current external factors.

[0180] See also Figure 8 Some advantages of this application are as follows: the operation of the photovoltaic system is more stable; the power optimizer is easier to adapt to different inverters; the power optimizer is fully coupled with the external inverter MPPT algorithm; by modifying the value of CRob, the power optimizer can be easily matched with different photovoltaic modules, which is convenient for string and parallel connection, etc.

[0181] See also Figure 8 Other advantages of the present application are as follows: CRob of different power optimizers can be modified online through communication and other means. When facing strings of different lengths in parallel, different CRobs can be set to achieve parallel matching.

[0182] See also Fig. 9 , after the PV modules PV1-PVN are connected in parallel, the inverter INVT uniformly optimizes the power of all the PV modules connected in series. At this time, centralized maximum power point tracking MPPT is performed. The two output ends of a digital power supply or a switching power supply regulator such as H1 are connected to the DC bus LA and the DC bus LB respectively. The two output ends of a digital power supply or a switching power supply regulator such as H2 are connected to the DC bus LA and the DC bus LB respectively. The two output ends of a digital power supply or a switching power supply regulator such as HN are connected to the DC bus LA and the DC bus LB respectively. In addition to changing the series architecture of the digital power supply or the switching power supply regulator to a parallel architecture, the technical features of the digital power supply or the switching power supply regulator under the series architecture recorded in the previous text are also applicable to the parallel architecture shown in the figure.

[0183] See also Fig. 9 , multiple switching power regulators H1-HN are connected in parallel to form a link, each switching power regulator such as HN is used to track the appropriate power point MSPN of the corresponding photovoltaic component such as PVN, and the maximum power point MPP of the link is tracked to compress the range such as Rg_N. An inverter with MPPT function or other power conversion equipment with MPPT function can be used to track the maximum power point MPP of the link.

[0184] See also Fig. 9, in view of the fact that the photovoltaic components are greatly affected by external environmental factors. In some cases, only part but not all of the switching power regulator gains in the system can work at their upper and lower limits, or in other words, a small part or even most of the switching power regulator gains cannot work completely at their upper and lower limits, but this does not affect the power optimization implemented by this application for individual photovoltaic components and the power optimization implemented for the entire photovoltaic system. Therefore, by allowing the gain to track the upper limit of the range or the lower limit of the range, the appropriate power point of the photovoltaic component is tracked, which means that the gain of the switching power regulator is not equal to the upper and lower limits. It is allowed. In an optional embodiment, the difference between the gain and CRob does not exceed the predetermined rated value or is within the predetermined rated range, then the appropriate power of the photovoltaic component is tracked. Or in other optional embodiments, the gain of the switching power regulator and CRob currently have a previous difference, and the gain of the switching power regulator continues to approach CRob. After that, they have the next difference, and the power of the photovoltaic component under the next difference is larger than the power of the photovoltaic component under the previous difference, then the appropriate power of the photovoltaic component is tracked. Based on the condition of the previous difference, the gain of the switching power supply regulator approaches CRob, so the next difference is smaller than the previous difference. The above examples are actually in line with the main purpose of this application, that is, by allowing the gain to track the upper limit of the range or the lower limit of the range, so as to track the appropriate power point of the photovoltaic component and other related descriptions. In addition, tracking CRmp can rely on an inverter with MPPT function or other power conversion equipment with MPPT function.

[0185] See also Figure 4 , the upper limit CRob in the figure is a preset value. The switching power regulator such as HN is equipped with a microprocessor for driving the switching power regulator such as HN to perform voltage or current conversion. The microprocessor adjusts the gain CRwk by changing the duty cycle of the switching power regulator such as HN when it is working, so that the gain CRwk approaches the prescribed value and allows the gain CRwk at this time to approach or approach or be equal to or approximately equal to the upper limit CRob.

[0186] See also Figure 4 , the lower limit CRmp in the figure is the gain when the photovoltaic module such as PVN is at the maximum power point state and the switching power regulator such as HN has the maximum power output. A plurality of switching power regulators H1-HN are connected in series or in parallel to form a link so that the gain GN=CRwk. The method of tracking the lower limit CRmp includes: approaching the gain to the lower limit CRmp by tracking the maximum power point of the link. This example is also applicable to digital power supply. In this example, the gain CRwk at this time is also allowed to be close to or approach or equal to or approximately equal to the lower limit CRmp.

[0187] See also Figure 4In an optional embodiment, the way of compressing the scale of the range such as Rg_N includes: making the upper limit and the lower limit coincide with each other, for example, the upper limit CRob is close to or approaches or is equal to or approximately equal to the lower limit CRmp.

[0188] See also Figure 4 In an optional embodiment, the upper and lower limits coincide with each other, including: when a photovoltaic module such as PVN operates at its maximum power point MPP, the gain of a switching power regulator such as HN tends to coincide with the upper limit and tends to coincide with the lower limit. For example, the gain GN=CRwk tends to coincide with the upper limit CRob and the lower limit CRmp.

[0189] See also Figure 4 In an optional embodiment, the situation where the upper and lower limits do not overlap includes: when a photovoltaic module such as PVN is not operating at its maximum power point MPP, the gain of a switching power supply regulator such as HN is between the upper and lower limits, for example, the gain GN=CRwk satisfies CRmp<CRwk<CRob.

[0190] See also Fig. 9 , compared with Figure 4 , the upper and lower limits are reversed. Figure 4 and Fig. 9 The upper and lower limits are not reversed or reversed, which is applicable to the series or parallel scenarios of switching power supply regulators or digital power supplies.

[0191] See also Fig. 9 , the lower limit CRob in the figure is a preset specified value. The switching power regulator such as HN is equipped with a microprocessor for driving the switching power regulator such as HN to perform voltage or current conversion. The microprocessor adjusts the gain CRwk by changing the duty cycle of the switching power regulator such as HN when it is working, so that the gain CRwk approaches the specified value and allows the gain CRwk at this time to approach or approach or be equal to or approximately equal to the lower limit CRob.

[0192] See also Fig. 9 , the upper limit CRmp in the figure is the gain when the photovoltaic module such as PVN is at the maximum power point state and the switching power regulator such as HN has the maximum power output. A plurality of switching power regulators H1-HN are connected in series or in parallel to form a link so that the gain GN=CRwk. The method of tracking the upper limit CRmp includes: approaching the gain to the upper limit CRmp by tracking the maximum power point of the link. This example is also applicable to digital power supply. In this example, the gain CRwk at this time is also allowed to be close to or approach or equal to or approximately equal to the upper limit CRmp.

[0193] See also Fig. 9In an optional embodiment, the way of compressing the scale of the range such as Rg_N includes: making the upper limit and the lower limit coincide, for example, the upper limit CRmp is close to or approaches or is equal to or approximately equal to the lower limit CRob.

[0194] See also Fig. 9 In an optional embodiment, the upper and lower limits coincide with each other, including: when a photovoltaic module such as PVN operates at its maximum power point MPP, the gain of a switching power regulator such as HN tends to coincide with the upper limit and tends to coincide with the lower limit. For example, the gain GN=CRwk tends to coincide with the upper limit CRmp and the lower limit CRob.

[0195] See also Fig. 9 In an optional embodiment, the situation where the upper and lower limits do not overlap includes: when a photovoltaic module such as PVN is not operating at its maximum power point MPP, the gain of a switching power supply regulator such as HN is between the upper and lower limits, for example, the gain GN=CRwk can satisfy CRob<CRwk<CRmp.

[0196] The above description and drawings provide typical embodiments of specific structures of specific embodiments, and the above invention provides existing preferred embodiments, but these contents are not intended to be limiting. For those skilled in the art, various changes and modifications will undoubtedly be obvious after reading the above description. Therefore, the attached claims should be regarded as covering all changes and modifications to the true intent and scope of the present invention. Any and all equivalent scopes and contents within the scope of the claims should be considered to still be within the intent and scope of the present invention.

Claims

1. A method for tracking a suitable power point, characterized in that: include: Using a switching power regulator to implement DC to DC power conversion for photovoltaic modules; During the power conversion stage, the gain of the switching power supply regulator is adjusted within a range, and the gain is allowed to track the upper limit or the lower limit of the range, thereby tracking the appropriate power point of the photovoltaic component.

2. The method according to claim 1, characterized in that: A plurality of switching power regulators are connected in series or in parallel to form a link, each switching power regulator is used to track the appropriate power point of the photovoltaic module corresponding thereto, and the scale of the range is compressed by tracking the maximum power point of the link.

3. The method according to claim 2, characterized in that: Ways to compress the size of the range include reducing the gap between the upper and lower limits.

4. The method according to claim 2, characterized in that: An inverter with MPPT function is used to track the maximum power point of the link.

5. The method according to claim 2, characterized in that: Ways to compress the scale of the range include making the upper limit and the lower limit coincide with each other.

6. The method according to claim 5, characterized in that: The situation where the upper limit and the lower limit coincide with each other includes: when the photovoltaic module operates at its maximum power point, the gain of the switching power supply regulator tends to coincide with the upper limit and the lower limit.

7. The method according to claim 3, characterized in that: The situation where the upper limit and the lower limit do not coincide includes: the situation where the photovoltaic module is not operating at its maximum power point, and the gain of the switching power supply regulator is between the upper limit and the lower limit.

8. The method according to claim 1, characterized in that: in, The upper limit is a pre-set specified value.

9. The method according to claim 8, characterized in that: The switching power regulator is equipped with a microprocessor for driving the switching power regulator to perform voltage or current conversion. The microprocessor adjusts the gain by changing the duty cycle of the switching power regulator when it is working, so that the gain approaches a specified value.

10. The method according to claim 1, characterized in that: in, The lower limit is the gain when the PV panel is below the maximum power point and the switching power supply regulator has maximum power output.

11. The method according to claim 10, characterized in that: A method of connecting a plurality of switching power supply regulators in series or in parallel into a link so that the gain tracks a lower limit includes: approaching the gain to the lower limit by tracking the maximum power point of the link.

12. The method according to claim 1, characterized in that: in, The lower limit is a pre-set specified value.

13. The method according to claim 12, characterized in that: The switching power regulator is equipped with a microprocessor for driving the switching power regulator to perform voltage or current conversion. The microprocessor adjusts the gain by changing the duty cycle of the switching power regulator when it is working, so that the gain approaches a specified value.

14. The method according to claim 1, characterized in that: in, The upper limit is the gain when the PV panel is below the maximum power point and the switching power regulator has maximum power output.

15. The method according to claim 10, characterized in that: A method of connecting a plurality of switching power supply regulators in series or in parallel into a link so that the gain tracks the upper limit includes: tracking the maximum power point of the link to approach the gain to the upper limit.

16. The method according to claim 1, characterized in that: The gain includes a voltage gain or a current gain.

17. A suitable power point tracking device, characterized in that: include: The digital power supply is used to implement DC to DC power conversion for the photovoltaic module. The gain of the digital power supply in the power conversion stage is set to operate within a range. By allowing the gain of the digital power supply to track the upper limit or the lower limit of the range, the purpose of tracking the appropriate power point of the photovoltaic module is achieved.

18. The suitable power point tracking device according to claim 17, characterized in that: A plurality of digital power supplies are connected in series or in parallel to form a link, and each digital power supply is used to track the appropriate power point of the photovoltaic component corresponding thereto, and the scale of the range is compressed by tracking the maximum power point of the link.

19. The suitable power point tracking device according to claim 18, characterized in that: Ways to compress the size of the range include reducing the gap between the upper and lower limits.

20. The suitable power point tracking device according to claim 17, characterized in that: The digital power supply is equipped with a microprocessor for driving the digital power supply to perform voltage conversion or current conversion. The microprocessor adjusts the gain by changing the duty cycle of the digital power supply when it is working so that the gain approaches a specified value, and the upper limit is a preset specified value.

21. The suitable power point tracking device according to claim 17, characterized in that: A method of connecting multiple digital power supplies in series or in parallel into a link and forcing the gain to track a lower limit includes: approaching the gain to a lower limit by tracking the maximum power point of the link, wherein the lower limit is the gain when the photovoltaic component is at the maximum power point and the digital power supply has a maximum power output.

22. The suitable power point tracking device according to claim 17, characterized in that: The digital power supply is equipped with a microprocessor for driving the digital power supply to perform voltage conversion or current conversion. The microprocessor adjusts the gain by changing the duty cycle of the digital power supply when it is working, so that the gain approaches a specified value, and the lower limit is a preset specified value.

23. The suitable power point tracking device according to claim 17, characterized in that: A method of connecting multiple digital power supplies in series or in parallel into a link and forcing the gain to track an upper limit includes: approaching the gain to the upper limit by tracking the maximum power point of the link, and the upper limit is the gain when the photovoltaic component is at the maximum power point state and the digital power supply has a maximum power output.

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