Power optimizer and method for realizing power optimization

Abstract

The invention relates to a power optimizer and a method for realizing power optimization. Relates to the field of photovoltaic power generation. The power optimizer comprises a voltage converter used for converting electric energy extracted from the photovoltaic module into output power, and a specified output parameter and a specified input parameter of the voltage converter are compared to obtain an actual conversion ratio. And performing power optimization on the photovoltaic module in a manner of reducing the difference between the actual transformation ratio and a preset target transformation ratio.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of photovoltaic power generation, and more specifically, to a power optimizer and a method for realizing power optimization by the power optimizer. Background Art

[0002] Energy is an indispensable resource for life and economic development. It is also a more obvious contradiction between the actual needs of human beings and the consumption of natural resources. With the non-renewable nature of traditional chemical energy such as oil, coal, and natural gas, they are becoming increasingly depleted and also lead to negative environmental problems such as pollution and greenhouse effect. Energy is an important material basis for the existence of human society and social progress. With the development of industrial economy and the decreasing energy, solar energy, as one of the important new energy sources, is developing rapidly with its advantages of never-exhausting and pollution-free.

[0003] Solar energy is widely distributed and almost endless. One of the problems with using solar photovoltaic power generation is that photovoltaic energy is intermittent and uncertain, making it difficult to provide a continuous and stable power supply to the load. Since photovoltaic module mismatch is hidden, many solar power generation systems may ignore or be unaware of the photovoltaic module mismatch problem, which will significantly reduce the return on investment and profits, and cause energy waste, so power optimization comes into being.

[0004] There are many reasons for the mismatch of photovoltaic modules, mainly caused by the mismatch of voltage and current. The mismatch of photovoltaic modules induces unbalanced power loss of photovoltaic modules due to local foreign objects shading and floating clouds, obstruction by nearby objects, surface pollution, different installation angles and installation directions, aging and temperature changes and many other factors. The result is that the entire photovoltaic power generation system cannot operate at the maximum output power point. The current photovoltaic power optimization often only attempts 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, and may not take into account the power optimization of the series and 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 and parallel requirements of the components. Summary of the invention

[0005] The present application relates to a power optimizer, comprising: A voltage converter is used to convert the electric energy captured from the photovoltaic module into output power. The actual conversion ratio is obtained by comparing the specified output parameters of the voltage converter with the specified input parameters. The actual conversion ratio is brought closer to the preset target conversion ratio to implement power optimization for the photovoltaic assembly (eg, power optimization for the photovoltaic assembly is implemented in a manner of reducing the difference between the actual conversion ratio and the preset target conversion ratio).

[0006] In the above power optimizer, the specified output parameter and the specified input parameter are the output voltage and the input voltage respectively.

[0007] In the above power optimizer, the specified output parameter and the specified input parameter are the output current and the input current respectively.

[0008] In the above power optimizer, the voltage converter is selected from any one of a buck converter, a boost converter, and a buck-boost converter.

[0009] The above-mentioned power optimizer connects the multi-level voltage converters in series, and a power converter performs power conversion on the output power provided by the multi-level voltage converters. The power converter has a maximum power tracking function, and the power converter performs maximum power tracking on multiple photovoltaic modules corresponding to the multi-level voltage converters connected in series as a whole.

[0010] The above-mentioned power optimizer connects the multi-level voltage converters in parallel, and a power converter performs power conversion on the output power provided by the multi-level voltage converters. The power converter has a maximum power tracking function, and the power converter performs maximum power tracking on multiple photovoltaic modules corresponding to the parallel multi-level voltage converters as a whole.

[0011] The power optimizer connects the multi-level voltage converters in series, and a power converter performs maximum power tracking on the output power provided by the multi-level voltage converters, wherein the power converter has an MPPT function.

[0012] The power optimizer connects the multi-level voltage converters in parallel, and a power converter performs maximum power tracking on the output power provided by the multi-level voltage converters, wherein the power converter has an MPPT function.

[0013] In the above-mentioned power optimizer, the power converter includes an inverter for performing DC to AC conversion, or includes a DC converter for performing DC to DC conversion.

[0014] In the above power optimizer, a plurality of photovoltaic modules corresponding to a group of multi-level voltage converters connected in series are regarded as a string; and power is supplied to the power converter by a single string or a plurality of parallel strings.

[0015] In the above power optimizer, a plurality of photovoltaic modules corresponding to a group of parallel multi-level voltage converters are regarded as a row group; and power is supplied to the power converter by a single row group or a plurality of parallel rows groups.

[0016] In the above power optimizer, the power converter sets the string current and string voltage of any single string at its maximum power point.

[0017] When a plurality of parallel strings supply power to the power converter, the power optimizer sets different target conversion ratios of voltage converters corresponding to different strings with unequal numbers of photovoltaic modules.

[0018] In the above power optimizer, the target conversion ratio of the voltage converter corresponding to the string with a small number of photovoltaic modules is set to be larger than the target conversion ratio of the voltage converter corresponding to the string with a large number of photovoltaic modules.

[0019] The above-mentioned power optimizer sets the target conversion ratios of different voltage converters among the multi-stage voltage converters corresponding to a single string to be different or the same.

[0020] The present application relates to a method for realizing power optimization, wherein: A voltage converter is used to convert the electrical energy captured from the photovoltaic module into output power. The specified output parameters of the voltage converter are compared with the specified input parameters to obtain the actual conversion ratio. By bringing the actual conversion ratio closer to a preset target conversion ratio, power optimization is implemented for the photovoltaic component (for example, in the stage where the voltage converter implements power optimization for the photovoltaic component, the difference between the actual conversion ratio and the preset target conversion ratio is reduced to achieve the optimization purpose of increasing the power of the photovoltaic component).

[0021] In the above method, the specified output parameter and the specified input parameter are the output voltage and the input voltage respectively, or the specified output parameter and the specified input parameter are the output current and the input current respectively.

[0022] The above method connects the multi-level voltage converters in series, and a power converter performs power conversion on the output power provided by the multi-level voltage converters. The power converter has a maximum power tracking function, and the power converter performs maximum power tracking on multiple photovoltaic components corresponding to the multi-level voltage converters connected in series as a whole.

[0023] The above method connects the multi-level voltage converters in parallel, and a power converter performs power conversion on the output power provided by the multi-level voltage converters. The power converter has a maximum power tracking function, and the power converter performs maximum power tracking on multiple photovoltaic components corresponding to the parallel multi-level voltage converters as a whole.

[0024] In the above method, a plurality of photovoltaic modules corresponding to a group of multi-level voltage converters connected in series are regarded as a group string; and power is supplied to the power converter by a single group string or a plurality of parallel groups strings.

[0025] In the above method, a plurality of photovoltaic modules corresponding to a group of parallel multi-level voltage converters are regarded as a row group; power is supplied to the power converter by a single row group or a plurality of parallel rows groups.

[0026] In the above method, the power converter sets the string current and string voltage of any single string at its maximum power point. For example, at this time, the unshaded photovoltaic components in the single string are at their maximum power point, and the photovoltaic components in the single string that are shaded are at the current optimal power point instead of the maximum power point.

[0027] In the above method, the voltage converter is configured with a controller for manipulating the voltage converter to perform voltage conversion, and the controller reduces the difference between the actual conversion ratio and the preset target conversion ratio (i.e., controls the actual conversion ratio to approach the preset target conversion ratio) by changing the actual conversion ratio when the voltage converter is working.

[0028] In the above method, the size of the target conversion ratio received by the controller is programmable and adjustable.

[0029] The present application relates to a power optimizer, comprising: A DC / DC converter is used to implement power optimization for a photovoltaic module, wherein a voltage-based target conversion ratio is set for the DC / DC converter, wherein an actual conversion ratio is obtained by comparing the output voltage of the DC / DC converter during operation with the input voltage, and the actual conversion ratio approaches a preset target conversion ratio to implement power optimization for the photovoltaic module (for example, power optimization is implemented in a manner that reduces the difference between the actual conversion ratio and the target conversion ratio).

[0030] The above-mentioned power optimizer connects multiple stages of DC / DC converters in series, wherein a power converter performs power conversion on the output power provided by the DC / DC voltage converter. The power converter has a maximum power point tracking function, and the power converter performs maximum power point tracking on multiple photovoltaic modules corresponding to the multiple stages of DC / DC converters connected in series as a whole.

[0031] The above-mentioned power optimizer connects multiple stages of DC / DC converters in parallel, wherein a power converter performs power conversion on the output power provided by the DC / DC voltage converter, and the power converter has a maximum power point tracking function, and the power converter performs maximum power point tracking on multiple photovoltaic modules corresponding to the parallel multi-stage DC / DC converters as a whole.

[0032] In the above power optimizer, a plurality of photovoltaic modules corresponding to a group of multi-level DC / DC converters connected in series are regarded as a group string, and a single group string or a plurality of parallel groups string supply power to the power converter. For example, at this time, the photovoltaic modules that are not blocked in any group string are at their maximum power point, and the photovoltaic modules that are blocked in any group string are at the current optimal power point instead of the maximum power point.

[0033] In the above-mentioned power optimizer, the voltage converter is provided with a controller for operating the voltage converter to perform voltage conversion and the controller reduces the difference by changing the actual conversion ratio when the voltage converter works.

[0034] In the above-mentioned power optimizer, the voltage conversion includes performing step-down voltage conversion, step-up voltage conversion or step-up / step-down voltage conversion.

[0035] In the above-mentioned power optimizer, the controller realizes the change of the actual conversion ratio by adjusting the duty cycle of the pulse width modulation signal used to drive the voltage converter to perform voltage conversion.

[0036] In the above-mentioned power optimizer, the voltage converter is also configured with a current sensor for sensing the input current and / or output current of the voltage converter, and the voltage converter is also configured with a voltage sensor for sensing the input voltage and / or output voltage of the voltage converter. The current sensor and the voltage sensor transmit the collected current information (input current and / or output current) and / or voltage information (input voltage and / or output voltage) to a controller configured with the voltage converter.

[0037] The present application relates to a power optimizer, comprising: A DC / DC converter is used to implement power optimization for a photovoltaic module, wherein a current-based target conversion ratio is set for the DC / DC converter, wherein an actual conversion ratio is obtained by comparing the output current and input current of the DC / DC converter during operation, and the actual conversion ratio approaches a preset target conversion ratio to implement power optimization for the photovoltaic module (for example, power optimization is implemented in a manner of reducing the difference between the actual conversion ratio and the target conversion ratio). BRIEF DESCRIPTION OF THE DRAWINGS

[0038] 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.

[0039] Figure 1 The inverter can perform centralized optimization for multi-stage PV modules and multi-stage PV modules connected in series.

[0040] Figure 2 is a schematic diagram of an example of an overall architecture of multi-stage photovoltaic modules and a multi-stage voltage converter connected in series.

[0041] Figure 3 It is an example of a multi-level voltage converter connected in series to power a DC converter that replaces a photovoltaic inverter.

[0042] Figure 4 It is an example of connecting multiple photovoltaic modules in series to form strings and then connecting multiple strings in parallel.

[0043] Figure 5 It is an example of a voltage converter using integrated buck conversion and boost conversion and buck-boost conversion functions.

[0044] Figure 6 It is a series voltage converter that powers the charger instead of a photovoltaic inverter or DC converter.

[0045] Figure 7 The target conversion ratio received by the controller is set to be programmable and the size of the target conversion ratio is adjustable.

[0046] Figure 8 It is to guide the local power optimization of PV panels and the power optimization of inverter end to adapt to each other.

[0047] Fig. 9 It is an example of connecting multiple photovoltaic modules in parallel to form rows and then connecting multiple rows in parallel. Implementation

[0048] 0048. The technical solutions disclosed in the present application will be clearly and completely explained below in conjunction with various specific embodiments. However, the embodiments described are only embodiments used for narrative explanation in the present application and 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.

[0049] See also Figure 1 , the full name of the power optimizer or MPPT (Maximum Power Point Tracking) controller is the maximum power point tracking solar controller. The way to achieve the best power of the photovoltaic module is MPPT. At present, it is common to connect all photovoltaic panels to a single inverter INVT to perform MPPT. This method can centrally control the MPPT function by the photovoltaic inverter, which requires a large number of complex control operations. When the lighting conditions of the panels are consistent, this system can work normally, but when some solar panels have performance mismatches or shadows, the power efficiency of this system will be greatly reduced. Therefore, the power optimization function of the voltage converter HN is introduced.

[0050] See also Figure 1 , different 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, different 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 working current of the DC bus multiplied by the optimal working 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 can be set at their maximum power point.

[0051] See also Figure 1 , power optimization The photovoltaic power generation system widely used at present connects all the components in series and parallel directly to the centralized inverter to transmit electricity to the power grid system. The framework structure shown in the figure can only adjust the maximum power of the entire system, and cannot track and control the individual power of each panel or component of each string in the photovoltaic system through MPPT, so it cannot guarantee the maximum power output of each panel. As long as any panel in each string is shaded by light, the other panels in this string will be affected, and the output voltage will be pulled to an unreasonable value, resulting in energy loss. Figure 2 Yes Figure 1 Optimization improvements.

[0052] See also Figure 2 The power optimization mentioned in this article includes: maximum power tracking implemented to reach the maximum power point, or power increase implemented to reach the maximum power point as much as possible, or power boost implemented when the maximum power point cannot be reached but efforts are made to approach the maximum power point, or any optimization behavior to increase the power of photovoltaic modules.

[0053] See also Figure 2 , the photovoltaic module array is the basis for photovoltaic power generation to convert light energy into electrical energy. The photovoltaic module array is equipped with a battery string, which is composed of photovoltaic modules PV1 to PVN connected in series. Each photovoltaic module or photovoltaic panel is equipped with a voltage converter or power optimizer that performs maximum power tracking calculations. In a certain battery string, for example, the power generated by the first-level photovoltaic module PV1 shown in the figure is converted by the first-level voltage converter H1 to perform power optimization, and the power generated by the second-level photovoltaic module PV2 is converted by the second-level voltage converter H2 to perform power optimization. And so on, until the power generated by the N-th photovoltaic module PVN shown in the figure is converted by the N-th voltage converter HN to perform power optimization, N is a positive integer not less than 1.

[0054] See also Figure 2 , set the output voltage V of the first stage voltage converter H1 O1 , and the output voltage V corresponding to the second-stage voltage converter H2 O2 , ... and so on, until the output voltage V of the voltage converter HN of the Nth stage ON The total string voltage of any photovoltaic cell string is calculated to be approximately V O1 +V O2 +…V ON =V BUS The voltage converter used in this application is also called a maximum power point tracker, and usually uses a specific type of topology circuit to search for the maximum power point and allow the voltage converter to extract the maximum possible power from the photovoltaic module.

[0055] 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 voltage converter HN 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 voltage converter HN has successfully implemented power optimization for the photovoltaic module PVN.

[0056] See also Figure 2 , the multi-level voltage converters H1-HN are connected in series, and the power converter 100 performs power conversion on the output power provided by the multi-level voltage converters H1-HN, that is, performs power conversion on the sum of the output powers of the multi-level voltage converters H1-HN, which is the same meaning. The total electric energy provided by the photovoltaic component array is transmitted to the power converter 100 by the DC bus. There are many types of power converters 100, for example, at least including Figure 1 The inverter INVT that can convert DC power into AC power or the charger CHAR that charges the battery, etc.

[0057] See also Figure 2 The power converter 100 has a maximum power tracking function, and the power converter 100 can implement maximum power tracking for the photovoltaic components PV1-PVN corresponding to the multi-level voltage converters H1-HN in series as a whole. Note that the photovoltaic inverter INVT used in almost all distributed or centralized photovoltaic power stations currently has a maximum power tracking function, which brings some disadvantages: the local power optimization of the photovoltaic components PV1-PVN and the power optimization of the photovoltaic inverter INVT will interfere with each other. How to guide this constraint relationship to the mutual adaptation of H1-HN and INVT to adaptively meet the optimization needs of both parties and achieve power maximization is a difficult problem.

[0058] See also Figure 2 , if no measures are taken, assuming that the conventional voltage converter H1-HN 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 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 this tracking action of the photovoltaic inverter INVT will break the power balance of the voltage converter H1-HN. At this moment, it is extremely difficult to achieve working adaptation between the voltage converter and the photovoltaic inverter and meet the optimization requirements of both.

[0059] See also Figure 2 In order to solve the above difficulties, the MPPT function of the photovoltaic inverter INVT can be abandoned. The optimization products currently on the market have adopted this kind of solution. For example, the power optimization solution of SOLAREDGE is to perform power optimization only in the photovoltaic module PV1-PVN locally instead of in the inverter INVT. 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 photovoltaic MPPT function to adapt to the local optimization of photovoltaic modules PV1-PVN. Therefore, this makes it difficult for the power optimization function configured at the voltage converter end 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 voltage converter 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 the current photovoltaic system is compatible with photovoltaic inverters with MPPT function. The various software architectures and hardware parts of the current photovoltaic system are based on catering to photovoltaic inverters with MPPT function. 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. Abandoning the MPPT function of photovoltaic inverter INVT is unacceptable for many existing photovoltaic power stations or newly built photovoltaic power stations, and it will also lose the opportunity for secondary optimization.

[0061] See also Figure 2It is necessary to retain the MPPT function of the photovoltaic inverter INVT, but as mentioned above, how to achieve adaptation between the voltage converter H1-HN and the inverter INVT and meet the optimization requirements of both is a difficult point in the design of the photovoltaic system. Some solutions have designed two MPPT coexistence architectures, but the mainstream idea is to realize the current I of the photovoltaic module PVN in the local voltage converter H1-HN. PVN Multiply the voltage V PVN Maximize and realize the current I at the busbar BUS Multiply the voltage V BUS Maximization, the coexistence of the two MPPTs still has irreconcilable difficulties. For example, facing different PV module application scenarios (different degrees of shading of PV modules, different numbers of PV modules in series in different strings, and randomness of the number of strings in parallel string relationships, etc.), how to programmably correct and adjust the maximum power tracking is a great challenge. In other words, simply realizing the current I of the PV module at the PVN of the PV module PVN Multiply the voltage V PVN The maximization of the optimization effect is almost equivalent to letting it run freely. The local photovoltaic power optimization of the photovoltaic module and the post-stage photovoltaic power optimization of the inverter still interfere with and constrain each other. These traditional solutions lack the flexibility and freedom to cope with different photovoltaic module application scenarios, and the optimization effect is not optimal.

[0062] See also Figure 2 In order to solve the above-mentioned drawbacks, the power optimizer involved in the present application uses the aforementioned voltage converters H1-HN. Taking the voltage converter H1 as an example, the voltage converter H1 converts the electric energy captured from the corresponding photovoltaic component PV1 into the output power of the voltage converter H1. The specified output parameters of the voltage converter H1 are V O1 and specify input parameters such as V I1 The actual conversion ratio R is obtained by comparison O1 . V O1 is the output voltage of voltage converter H1 and V I1 is the input voltage of the voltage converter H1, that is, the voltage provided by the photovoltaic module PV1. O1 The power of the photovoltaic module PV1 is optimized by calculating the difference between the conversion ratio Rob_V1 and the preset target conversion ratio Rob_V1.

[0063] See also Figure 2 Taking the voltage converter H2 as an example, the voltage converter H2 converts the electric energy captured from the corresponding photovoltaic module PV2 into the output power of the voltage converter H2. The specified output parameters of the voltage converter H2 are as follows: O2 and specify input parameters such as V I2 The actual conversion ratio R is obtained by comparison O2. V O2 is the output voltage of voltage converter H2 and V I2 is the input voltage of the voltage converter H2, that is, the voltage provided by the photovoltaic module PV2. O2 The power of the photovoltaic module PV2 is optimized by calculating the difference between the conversion ratio Rob_V2 and the preset target conversion ratio Rob_V2.

[0064] See also Figure 2 Taking the voltage converter HN as an example, the voltage converter HN converts the electric energy captured from the photovoltaic module PVN into the output power of the voltage converter HN. The specified output parameters of the voltage converter HN are as follows: ON and specify input parameters such as V IN The actual conversion ratio R is obtained by comparison ON . V ON is the output voltage of the voltage converter HN and V IN The input voltage of the voltage converter HN is the voltage provided by the photovoltaic module PVN. ON The power optimization of the photovoltaic module PVN is implemented in the form of the difference between the conversion ratio Rob_VN and the preset target conversion ratio Rob_VN.

[0065] See also Figure 2 In an optional embodiment, the target conversion ratios Rob_V1 and Rob_V2 and Rob_VN or the target conversion ratios Rob_V3 to Rob_V(N-1) set for other voltage converters H3 to H(N-1) may be the same or different.

[0066] See also Figure 2, voltage converters belong to power electronic devices, and their main purpose is to achieve the function of power point tracking of individual photovoltaic modules. Buck circuit, boost circuit, buck-boost circuit and CUK circuit are the main circuit topologies suitable for photovoltaic voltage converters. These main circuit topologies are essentially still in the category of switching power supply SMPS system. The switching power supply system usually uses power semiconductor devices as switching elements and adjusts the output voltage by periodically switching on and off to control the duty cycle of the switching elements. The power conversion achieved by the switching power supply is its core part. In order to meet the requirements of high power density, the converter needs to work at a high frequency and the switching transistors need to use power switches with high switching speed and short conduction and off time, such as power thyristors, power field effect transistors and insulated bipolar transistors. The main control methods of the switching converter are divided into pulse width modulation, pulse frequency modulation and other types, and pulse width modulation schemes are commonly used. The switching power converter shown in the figure is a DC to DC step-down or step-up or step-down voltage converter. After the voltage converter optimizes the power of a single photovoltaic module, the energy is transmitted to the inverter for DC to AC processing for local use or grid connection. 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).

[0067] See also Figure 2 , the voltage converters H1-HN still need to achieve power optimization of the corresponding photovoltaic components PV1-PVN but no longer simply track the MPPT (for example, maximizing the product of the output current and output voltage of the photovoltaic component). In other words, the power optimization pursued by the voltage converters H1-HN in this application may not be the maximum power point of the corresponding photovoltaic components PV1-PVN but the optimal power optimization, provided that it can achieve a high degree of adaptation with the MPPT of the inverter INVT. The optimal power may be the maximum power point of the photovoltaic components PV1-PVN, or it may not be their maximum power point. Note that the optimal power optimization has taken into account the coordination and cooperation with the MPPT of the inverter INVT.

[0068] See also Figure 2Strictly speaking, the power optimization of the voltage converter H1-HN at this time is not MPPT, but another power optimization method that can work in coordination with the MPPT of the inverter INVT. This design is based on the local voltage converter H1-HN and the secondary photovoltaic MPPT of the inverter INVT mentioned above, which may cause some mutual constraints and interference with each other, causing the photovoltaic components that have been parked at the maximum power point to deviate from the maximum power point, or to be in a see-saw change state of entering the maximum point and escaping the maximum point. Generally speaking, photovoltaic components and the voltage converters installed locally on the photovoltaic components, as well as photovoltaic supporting equipment such as junction boxes and inverters are not purchased from the same merchant. Current photovoltaic inverters are all equipped with MPPT functions, but the power optimization function of the local voltage converter has poor adaptability and cannot cooperate well with the MPPT function of the inverter. The power optimizer involved in this application can just solve this type of problem.

[0069] See also Figure 3 In order to solve the above-mentioned drawbacks, the power optimizer involved in the present application uses the aforementioned voltage converters H1-HN. Taking the voltage converter H1 as an example, the voltage converter H1 converts the electric energy captured from the corresponding photovoltaic component PV1 into the output power of the voltage converter H1. The specified output parameters of the voltage converter H1 are as follows: O1 and specify input parameters such as I I1 The actual conversion ratio R' is obtained by comparison O1 I O1 is the output current of voltage converter H1 and I I1 The corresponding current is the input current of the voltage converter H1, that is, the current provided by the photovoltaic module PV1. To reduce the actual conversion ratio R' O1 The power of the photovoltaic module PV1 is optimized by calculating the difference between the conversion ratio Rob_I1 and the preset target conversion ratio Rob_I1.

[0070] See also Figure 3 Taking the voltage converter H2 as an example, the voltage converter H2 converts the electric energy captured from the corresponding photovoltaic module PV2 into the output power of the voltage converter H2. The specified output parameters of the voltage converter H2 are as follows: O2 and specify input parameters such as I I2 The actual conversion ratio R' is obtained by comparison O2 I O2 is the output current of voltage converter H2 and I I2 The input current of the voltage converter H2 is the current provided by the photovoltaic module PV2. O2 The power of the photovoltaic module PV2 is optimized by calculating the difference between the conversion ratio Rob_I2 and the preset target conversion ratio Rob_I2.

[0071] See also Figure 3Taking the voltage converter HN as an example, the voltage converter HN converts the electric energy captured from the photovoltaic module PVN into the output power of the voltage converter HN. The specified output parameters of the voltage converter HN are as follows: ON and specify input parameters such as I IN The actual conversion ratio R' is obtained by comparison ON I ON is the output current of the voltage converter HN and I IN The input current of the voltage converter HN is the current provided by the photovoltaic module PVN. To reduce the actual conversion ratio R' ON The power optimization of the photovoltaic module PVN is implemented in the form of the difference between the conversion ratio Rob_IN and the preset target conversion ratio Rob_IN.

[0072] See also Figure 3 In an optional embodiment, the target conversion ratios Rob_I1 and Rob_I2 and Rob_IN or the target conversion ratios Rob_I3 to Rob_I(N-1) set for other voltage converters may be the same or different.

[0073] See also Figure 3 In an optional embodiment, the DC converter CONV performs power conversion on the output power provided by the voltage converters H1-HN, and the DC converter CONV has a maximum power tracking MPPT function. It is worth noting that the DC converter CONV is different from the inverter INVT: the inverter performs DC to AC (DC-AC) conversion on the output power provided by the voltage converters H1-HN, while the DC converter performs DC to DC (DC-DC) conversion on the output power provided by the voltage converters H1-HN. The former generates AC power, and the latter generates stable DC power.

[0074] See also Figure 3 In an optional embodiment, the DC converter CONV can be replaced by an inverter INVT or a battery charger CHAR. The DC converter CONV is essentially a voltage converter, and its common circuit topologies include the aforementioned buck circuit, boost circuit, buck-boost circuit, and another Cuk converter CUK circuit. The DC converter CONV includes a DC / DC switching power supply SMPS. In the optional embodiment shown in the figure, the DC converter CONV is a DC conversion device equipped with maximum power point tracking MPPT (for example, maximizing the product of bus voltage and bus current). In other words, the maximum power point tracking function MPPT equipped with the traditional photovoltaic inverter INVT can be transplanted to the DC converter CONV shown in the figure. In other words, the current operating current I of the photovoltaic module can be used. PVN Multiply its operating voltage V PVNThe traditional power optimizer that maximizes I is used to replace the DC converter CONV shown in the figure, but the traditional power optimizer does not pursue I PVN Multiply by V PVN Maximization, but the pursuit of bus current I BUS Multiply by bus voltage V BUS maximize.

[0075] See also Figure 4 , different groups of battery groups are connected in series and in parallel between busbars LA and LB: if a multi-level voltage converter H1-HN is defined to form a certain link, then different multiple links are connected in parallel between busbars LA and LB. If the voltage converter H1-HK forms another link, it is also connected between busbars LA and LB. This parallel relationship of the strings will bring some disadvantages in terms of optimization: if the number of components connected in series N and K are not equal, that is, as mentioned above, facing different photovoltaic component application scenarios, the MPPT of the inverter INVT guides the string (PV1-PVN) to work at the maximum power point, but it may not be able to make the string (PV1-PVK) work at the maximum power point. In fact, the total power that a larger number of photovoltaic components can provide is usually much greater than that of a smaller number of photovoltaic components. K is a positive integer not less than 1.

[0076] See also Figure 4 The more difficult problem is that each voltage converter H1-HN corresponding to the string (PV1-PVN) attempts to maximize the power of the corresponding photovoltaic module (PVN). In this working state, the output voltage of each voltage converter H1-HN will inevitably generate a string voltage V O1 +V O2 +…V ON .

[0077] See also Figure 4 In contrast, each voltage converter H1-HK corresponding to another string (PV1-PVK), such as HK, attempts to maximize the power of the corresponding PV module, such as PVK. In this working state, the output voltages of the voltage converters H1-HK will inevitably generate another string voltage V O1 +V O2 +…V OK .

[0078] See also Figure 4 In most cases, V O1 +V O2 +…V ON and V O1 +V O2 +…V OKNot equal. However, for the photovoltaic inverter INVT, there is only one bus voltage value corresponding to the maximum power point of the DC bus, so there is a matching problem between different strings, which leads to the disorder of the photovoltaic inverter INVT in executing MPPT. At this time, the great advantages of the present application are fully demonstrated. As long as the target conversion ratio of different strings is slightly modified, the bus voltages contributed by different strings can be infinitely close. For example: If N>K, the target conversion ratio of the voltage converter H1-HN corresponding to the string (PV1-PVN) is designed to be smaller than the target conversion ratio of the voltage converter H1-HK corresponding to the string (PV1-PVK), which can easily make the string voltage V O1 +V O2 +…V ON and V O1 +V O2 +…V OK In particular, the target conversion ratio of each voltage converter can be adjusted to be the same or different, which is extremely beneficial for making the string voltages of different strings equal or close when the inverter INVT performs power optimization. Undoubtedly, this is one of the manifestations of the power optimization function of the voltage converters H1-HN and the MPPT function of the inverter INVT or the power converter 100 coordinating with each other to achieve adaptation.

[0079] See also Figure 4 In an optional embodiment, the multi-level voltage converters are connected in series. As shown in the figure, a group of voltage converters H1-HK can be connected in series, a group of voltage converters H1-HN can be connected in series, or more other groups of multi-level voltage converters not shown can be connected in series, and different groups of voltage converters are connected in parallel. For example, the series connection structure of the multi-level voltage converter H1-HK is connected in parallel with the series connection structure of the multi-level voltage converter H1-HN. If there are other series connection structures of the multi-level voltage converters, then the different series connection structures are all connected in parallel.

[0080] See also Figure 4In an optional embodiment, a power converter 100 performs power conversion on the output power provided by a multi-level voltage converter (in this example, H1-HK and H1-HN as shown in the figure), and the power converter 100 may have a maximum power tracking MPPT function. The power converter 100 may implement maximum power tracking, i.e., MPPT, on a plurality of photovoltaic components such as PV1-PVN and PV1-PVK corresponding to the multi-level voltage converters (in this example, H1-HK and H1-HN as shown in the figure) connected in series. Note that the power converter 100 may use an inverter that provides AC power, a DC converter that provides stable DC power, or a charger that provides constant voltage / constant current charging current. Note that no matter what form of power conversion is used, the power converter 100 should preferably be equipped with a maximum power tracking MPPT (for example, maximizing the product of bus voltage and bus current). The inverter is suitable for occasions of grid-connected to mains or off-grid AC power, the DC converter is suitable for occasions requiring digital power, and the charger is suitable for occasions of battery charging.

[0081] See also Figure 4 In an optional embodiment, a plurality of photovoltaic modules PV1-PVN corresponding to a group of multi-level voltage converters H1-HN connected in series can be regarded as a group string (PV-string1), and a plurality of photovoltaic modules PV1-PVK corresponding to the multi-level voltage converter H1-HK can be regarded as another group string (PV-string2). More groups of strings are not shown in the figure.

[0082] See also Figure 2 In an optional embodiment, a single string supplies power to the power converter 100. In this example, the power converter converts the string current of the single string, i.e., I BUS And the string voltage V BUS Set at its maximum power point.

[0083] See also Figure 4 In an optional embodiment, multiple parallel strings are used to supply power to the power converter 100. In this example, the power converter converts the string current of a single string (PV1-PVN), that is, I N And the string voltage V BUS Set it at its maximum power point and also set the string current of a single string (PV1-PVK), that is, I K And the string voltage V BUS Set at its maximum power point. String current I N is the output current of the voltage converters H1-HN connected in series, the string current I K It is the output current of the voltage converters H1-HN connected in series.

[0084] See also Figure 4In an optional embodiment, when power is supplied to the power converter 100 by multiple strings connected in parallel, the target conversion ratios of the voltage converters corresponding to different strings (e.g., PV-string1, PV-string2) with unequal numbers of photovoltaic components are also set to be different. N and K are different. Then the target conversion ratio of the voltage converter H1-HN is set to be different from the target conversion ratio of the voltage converter H1-HK. Note that the target conversion ratios of different voltage converters in the voltage converters H1-HN can be set to be the same, and at the same time, the target conversion ratios of different voltage converters in other voltage converters H1-HK can be set to be the same.

[0085] See also Figure 4 In an optional embodiment, the target conversion ratio of the voltage converter H1-HK corresponding to the string with a small number of photovoltaic components (such as PV-string2) is larger than the target conversion ratio of the voltage converter H1-HN corresponding to the string with a large number of photovoltaic components (such as PV-string1).

[0086] See also Figure 4 In an optional embodiment, among the multi-level voltage converters corresponding to a single string (such as PV-string1), the target conversion ratios of different voltage converters H1-HN are set to be different or the same.

[0087] See also Figure 4 In essence, photovoltaic modules are only a specific example of an optimized object. The voltage converter 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 voltage converter has a broader meaning of implementing power optimization for different types of DC power sources, such as wind power and fuel cells. Any solution for maximum power tracking of DC buses in the prior art is also applicable to the power converter 100 of the present application. Common power optimization methods include constant voltage method, conductance increment method, perturbation observation method, etc.

[0088] See also Figure 4 In an optional embodiment, the goal of the photovoltaic power optimization mentioned in this application is to quickly respond to changes in photovoltaic module power and absorb frequently changing weak light radiation, so that distributed or centralized photovoltaic power stations have high photoelectric conversion efficiency and are compatible with existing photovoltaic systems and have more stable operation characteristics. Under the premise of being compatible with the MPPT tracking architecture of the photovoltaic inverter INVT of existing distributed power stations or centralized power stations, the multi-level voltage converter or power optimizer is completely coupled with the MPPT algorithm of the external inverter INVT, and the local power optimization of the photovoltaic module and the power optimization of the photovoltaic inverter will not interfere with each other. Even the local power optimizer of the photovoltaic module can cooperate with the maximum power tracking algorithm of the photovoltaic inverter to achieve the overall best optimization effect.

[0089] See also Figure 4 Based on the above advantages, the voltage converter or power optimizer disclosed in this application is easier to adapt to photovoltaic inverters of different types or different merchants than traditional power optimizers. Moreover, by modifying the target conversion ratio, the voltage converter or power optimizer disclosed in this application can easily match different types of photovoltaic modules: it should be noted that the voltage and current parameters of photovoltaic modules of different types or different merchants are not completely consistent, and even the voltage and current parameters of photovoltaic modules of the same type from the same merchant are not completely consistent (for example, in different production batches). A major drawback of traditional power optimizers is that the battery characteristics of different photovoltaic modules in the network are different. In order to be able to adaptably cooperate with photovoltaic modules under the same string but with different characteristics, traditional power optimizers require certain restrictions on the battery characteristics of photovoltaic modules, such as typically limiting its various voltage and current parameters, nominal power, etc., which leads to a significant increase in the cost of photovoltaic modules that can be networked. The power optimizer disclosed in this application implements power optimization by modifying the target conversion ratio, which does not necessarily mean to perform MPPT, but to optimize the power of photovoltaic modules by reducing the difference between the actual conversion ratio and the preset target conversion ratio. Then, the change of the target conversion ratio allows the power optimizer to adapt to photovoltaic modules with different battery characteristics, allowing power optimization of various types of photovoltaic modules with poor consistency under wide range parameters such as wide voltage and wide current. This is difficult for traditional power optimizers to achieve.

[0090] See also Figure 4 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 optimal power processing of the photovoltaic module PVN at the photovoltaic module end (under the optimal processing I PVN Multiply by V PVN It may or may not be the maximum), and it is worth noting that the latter does not calculate I PVN Multiply by V PVN The maximum tracking of the power amplifier is different from that of the power amplifier, so the latter usually does not know whether it is at its maximum power point.

[0091] See also Figure 4Under the above-mentioned conditions, different strings networked by traditional power optimizers lack sufficient layout flexibility. For example, it is required that the number of photovoltaic modules used in different strings should not differ too much. For example, it is required that 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. Assume that the string PV-string2 is a number of photovoltaic modules arranged on a narrow roof, and the string PV-string1 is a photovoltaic module arranged in a spacious courtyard attached to the house. At this time, the number of photovoltaic modules used in different strings is usually quite different. Traditional power optimizers are not very practical at this time, because the specific power optimization function that pursues the maximum power point limits the voltage floating range of the power optimizer, otherwise at least part of the photovoltaic modules will drift away from the maximum power point when catering to the parallel connection of the strings.

[0092] See also Figure 4 Under the above-mentioned conditions, the power optimizer of this article has sufficient layout flexibility between different strings of the network, such as allowing the number of photovoltaic modules used in different strings 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 fewer photovoltaic modules, K<N. At this time, some or all of the voltage converters in the voltage converter H1-HK only need to fine-tune their target conversion ratios. Under this condition, the power optimizer pursuing power optimization has a larger voltage floating range, because the change in the target conversion ratio is equivalent to the flexible expansion range of the input and output voltages of the voltage converter H1-HK. It is worth noting that this example does not allow the photovoltaic module to drift away from its optimal 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 optimal power position of the photovoltaic module.

[0093] See also Figure 4 , under the above-mentioned distinguishing conditions, the advantages of the power optimizer in this paper include: when strings of different lengths are connected in parallel, parallel matching can be achieved by setting different target conversion ratios, which is convenient for parallel connection of strings.

[0094] See also Figure 4 As explained above, the power optimizer in this paper is to pursue the optimal power processing of the photovoltaic module PVN at the photovoltaic module end (under the optimal processing I PVN Multiply by V PVNThe optimal power processing is intuitively reflected in at least the following: the voltage converter HN (N=1, 2, 3...) can continuously maintain the corresponding photovoltaic module PVN in a power-optimized state when freely configuring the ratio of output voltage to input voltage. In other words, power optimization and the free and flexible change of the output voltage and input voltage range of the voltage converter HN coexist at the same time. However, when the traditional power optimizer changes the ratio of output voltage to input voltage in the maximum power balance state, it may push the photovoltaic module from the original maximum power position MPPT to other power positions extremely far away from the MPPT point.

[0095] See also Figure 4 As mentioned above, the intuitive performance of optimal power processing is also reflected in: when the multi-stage voltage converters are connected in series, any voltage converter HN can flexibly configure the ratio of its output voltage to input voltage, then the cascade voltage V output by the multi-stage voltage converters H1-HN O1 +V O2 +…V ON There will be considerable flexibility, and the free expansion of the string voltage will not affect the power optimization operation of the multi-level voltage converter H1-HN. However, the traditional power optimizer 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.

[0096] See also Figure 4 , and then compare the power optimizer in this paper with the traditional power optimizer. It is known that when the traditional power optimizer performs power optimization on the corresponding photovoltaic module PVN (N=1, 2, 3...), it tracks its working current I PVN Multiply it by its operating voltage V PVN The bus voltage is the sum of the output voltages of the power optimizers in series, and the bus current is the sum of the currents flowing through the series structures in parallel. A series structure includes a series of multi-stage voltage converters such as H1-HN or H1-HK. When the inverter INVT periodically adjusts the bus voltage V BUS and bus current I BUS When tracking bus MPPT, the output voltage and output current of the traditional power optimizer are forced to change to cater to the bus voltage V BUS and bus current I BUSThe dynamic changes of the bus voltage and bus current induce the traditional power optimizer to drift the photovoltaic module PVN (N=1, 2, 3...) from its maximum power point to other power points suitable for tracking the bus voltage and bus current. This contradiction of the traditional power optimizer is difficult to reconcile.

[0097] See also Figure 4 In other words, the intuitive performance of optimal power processing is reflected in the following: when the voltage converter HN performs power optimization on the corresponding photovoltaic module PVN (N=1, 2, 3...), it optimizes the power of the photovoltaic module PVN by reducing the difference between its actual conversion ratio and the preset target conversion ratio. The inverter INVT frequently adjusts the bus voltage V 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, taking the voltage converter HN as an example, it will actively adjust the specified output parameters such as V ON and specify the input parameter V IN The actual transformation ratio R ON , we should try to make this actual transformation ratio R ON Close to a target conversion ratio Rob_VN. Consider the inverter INVT to adjust V BUS and I BUS It is the action required for maximum power tracking, and under this condition the actual conversion ratio R ON is changed by the optimized behavior of the voltage converter HN so that V ON and I N The adjustable power of the inverter INVT and the power optimization of the voltage converter HN will naturally not interfere with each other. Instead, the two will achieve a win-win effect of mutual cooperation and promotion, thereby improving the power conversion rate. Undoubtedly, this is another manifestation of the mutual coordination and adaptation between the power optimization of the voltage converters H1-HN and the MPPT of the inverter INVT or the power converter 100.

[0098] See also Figure 5 The voltage converter HK has been described in the previous article as a switch power supply SMPS, and the specific circuit topologies include Buck circuit, Boost circuit, Buck-Boost circuit, etc. Figure 5 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.

[0099] See also Figure 5Although the voltage converter HK or DC / DC converter belongs to the category of switching power supply SMPS, its optional topology is not limited to a specific type. In this example, the voltage converter HK preferably has both a boost circuit and a buck circuit. The main topology circuit of the power optimizer has been introduced above. The photovoltaic module PVK uses the voltage converter HK shown in the figure (assuming that K can be a number from 1 to N) to generate the desired output voltage and perform the desired power optimization. The first input terminal IN1 of the input side of the voltage converter 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 corresponding voltage converter HK provides an output voltage and output power between the first output terminal NO1 and the second output terminal NO2 on the output side. In addition, the input capacitor CI can be set in the topology to be connected between the first input terminal IN1 and the second input terminal IN2, and the output capacitor CO can be set to be connected between the first output terminal NO1 and the second output terminal NO2.

[0100] See also Figure 5 , the voltage converter or power optimizer performs DC / DC voltage conversion on the direct current of the photovoltaic module and synchronously performs power optimization tracking calculation. In the topological structure, the power switch S1 and the power switch S2 of the buck conversion circuit module in the voltage converter 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 voltage converter HK are connected in series between the first output terminal NO1 and the second output terminal NO2. Therefore, the main topological circuit adopts a switching power supply that can step up and down, and the buck conversion circuit and the boost conversion circuit share the same inductor device L.

[0101] See also Figure 5 , 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, and 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.

[0102] See also Figure 5 The controller 400 configured with the voltage converter 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.

[0103] See also Figure 5When multiple voltage converters are connected in series, the first output terminal NO1 of the voltage converter HK can be coupled to the second output terminal NO2 of the adjacent previous voltage converter H(K-1).

[0104] See also Figure 5 When multiple voltage converters are connected in series, the second output terminal NO2 of the voltage converter HK can be coupled to the first output terminal NO1 of the adjacent subsequent voltage converter H(K+1).

[0105] See also Figure 5 , the power switch is typically an insulated gate bipolar transistor or a semiconductor field effect transistor, etc. The voltage converter HK shown in the figure preferably has both a buck circuit and a boost circuit: for example, the power switches S1-S2 constitute a buck single arm of the buck circuit, and the D1 and D2 signals provided by the pulse width modulator of the aforementioned controller 400 can be used to drive the complementary switches S1 and S2 of the buck circuit respectively. S1-S2 switch at a 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.

[0106] See also Figure 5 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.

[0107] See also Figure 5 , the voltage converter's boost circuit Boost function is opposite to the buck circuit. The voltage converter HK shown in the figure has a boost circuit opposite to the buck circuit: for example, the power switches S3-S4 constitute a boost arm of the boost circuit, and 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 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.

[0108] See also Figure 5 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.

[0109] See also Figure 5In summary, the topology of the voltage converter 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.

[0110] See also Figure 5 , the multi-level voltage converters H1-HN are all equipped with a controller 400, and power optimization can be specifically implemented by the pulse width modulation signal output by the controller for driving the voltage converter. The controller and its configured peripheral hardware can collect various target parameters of photovoltaic components such as PVK or voltage converters such as HK, which is equivalent to a data collector. Capturing these target parameter data is helpful to achieve power optimization. In an optional example, the peripheral hardware can collect a series of related 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 voltage converter HK can also be detected by the voltage sensor 113, and the output current of the voltage converter HK can be detected by the current sensor 114.

[0111] See also Figure 5 The more types of peripheral hardware used for data collection, the more types of target parameters related to photovoltaic modules that the controller 400 can obtain. In a more complex embodiment, the various target parameters may also include data of environmental factors of the photovoltaic modules detected by an environmental monitor: ambient temperature and humidity, wind speed, light intensity, air pressure, etc. The environmental monitor is a highly integrated data collector.

[0112] See also Figure 5 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 actually the input voltage and input current of the voltage converter HK.

[0113] See also Figure 5 , target parameters related to the voltage converter HK, such as the output voltage and output current of the voltage converter, are transmitted to the controller 400 by the corresponding voltage sensor 113 and current sensor 114 .

[0114] See also Figure 5The 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.

[0115] See also Figure 2 , the voltage converters H1-HN are connected in series according to the following rule: the second output terminal of the previous voltage converter is coupled to the first output terminal of the adjacent next voltage converter. The second output terminal of the first voltage converter H1 is connected to the first output terminal of the second voltage converter H2, and the second output terminal of the second voltage converter H2 is connected to the first output terminal of the adjacent third voltage converter H3. And so on, until the second output terminal of the N-1 voltage converter H(N-1) is connected to the first output terminal of the N-1 voltage converter HN. Therefore, it can also be considered that the series voltage provided by the multi-stage voltage converters H1-HN connected in series 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 voltage converter H1 and the bus LB coupled to the second output terminal of the N-stage voltage converter HN.

[0116] See also Figure 4 At 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.

[0117] See also Figure 6, the power converter 100 uses a charger CHAR to charge the energy storage device. The photovoltaic power generation system is equipped with a power regulation function to cope with the power instability of the photovoltaic module. As mentioned above: factors such as shadow blocking and component aging, as well as light intensity and ambient temperature, will cause the power of the photovoltaic module to be unstable. The corresponding working voltage of the real-time power of the photovoltaic module will change with the changes in external factors, further causing the DC or AC power provided by the photovoltaic system to not meet the specifications. The negative impact is that, such as causing the power fluctuation impact of the power grid GRID, may exceed the voltage fluctuation range that the grid can tolerate. Therefore, one of the most basic problems that this application can solve is to add an energy storage part to the traditional photovoltaic power generation system to cope with the intermittent power fluctuations of the photovoltaic module. The charger CHAR can actually use a basic DC converter CONV, but the DC converter CONV needs to comply with the relevant rules of charging and discharging during charging, such as pre-charge, charge, and floating charge, which are typical charging schemes for multi-stage charging. It can be seen that the choice of power converter 100 is diverse.

[0118] See also Figure 6 , the MPPT of the inverter INVT can be transplanted to the charger CHAR. In addition to the conventional lead-acid batteries, lithium batteries, sodium-sulfur batteries and vanadium liquid flow batteries, any storage battery that performs charging and discharging is suitable for this application. In an optional embodiment, the storage battery can be coupled to the DC bus to feed the stored electric energy to the DC bus as an energy supply source, or the storage battery can be coupled to the DC bus to absorb electric energy on the bus and store the storage battery. In the application of storage batteries, lead-acid batteries, alkaline batteries, lithium batteries, supercapacitors, etc. are used in different occasions or products respectively. The most widely used one is the lead-acid battery, which has derived many modified storage battery types such as valve-regulated sealed lead-acid batteries, flooded lead-acid batteries, colloidal batteries and lead-carbon batteries. At present, the fastest growing is the lithium battery system, represented by lithium iron phosphate batteries and ternary lithium batteries, namely nickel cobalt manganese oxide batteries.

[0119] See also Figure 6The problems solved by this application include overcoming the intermittent and uncertain characteristics of light irradiation resources, striving to provide a continuous and stable power supply for the load, using an energy storage system to store or release electric energy, reducing the negative impact of factors such as weather or the quality of the components themselves and the location and orientation of the photovoltaic components on the photovoltaic power generation system, providing stable power supply to power users and ensuring the reliability and quality of power supply, and improving the energy management efficiency of the photovoltaic power generation system. Since the maximum power output of the photovoltaic component is determined by the intensity of sunlight, its output power is random and volatile, and this random and uncontrollable characteristic has a high probability of causing a large impact on the power grid, and may also have a negative impact on the operation of some important loads. The energy storage device can make up for this shortcoming of the photovoltaic power generation system. It operates under the working mechanism of peak shaving and valley filling and wave smoothing suppression of the output power of the photovoltaic power source, so that the energy storage has a certain range of power regulation. When the power generation is greater than the power consumption, the remaining electric energy is charged to the energy storage device and stored; when the power generation is insufficient, the energy storage device is called again and the stored electric energy can be released to supplement the power generation deficiency. When photovoltaic power generation changes suddenly, the energy storage device can also play a role of real-time compensation to balance the system output power.

[0120] See also Figure 7 In an optional embodiment, a data transmission terminal CTL with a communication function is used to send various communication data to the controllers 400 of each level of voltage converters H1-HN. The specific form of the data transmission terminal CTL is diverse, such as a microcomputer, a server, an intelligent gateway, a data transfer platform, etc. It is usually necessary to establish wired or wireless communication between the controller 400 at the voltage converter H1-HN and the data transmission terminal CTL.

[0121] See also Figure 7 In an optional embodiment, the communication data sent by the data sending end CTL to the controllers 400 respectively matched with each level of the voltage converters H1 -HN include target conversion ratios matched to the voltage converters H1 -HN respectively.

[0122] See also Figure 7 In an optional embodiment, both the data transmitting end CTL and the controller 400 are configured with a unidirectional or bidirectional communication module. In the illustrated embodiment, both the data transmitting end CTL and the controller 400 are configured with a power line carrier communication module. For example, the data transmitting end CTL sends communication data in the form of a power line carrier to the controllers of each level of voltage converters H1-HN, and the carrier data includes the target conversion ratio of each voltage converter H1-HN. For example, the communication data includes Rob_V1, Rob_V2, ..., Rob_VN or Rob_I1, Rob_I2, ..., Rob_IN. The illustrated power line carrier PLC can be replaced with wireless or wired communication modes such as 2G-6G, infrared, Bluetooth, WIFI, etc.

[0123] See also Figure 7 In an optional embodiment, the communication data sent by the data transmitting terminal CTL to the controller 400 is directly stored locally at the data transmitting terminal CTL itself. The data transmitting terminal CTL may also be referred to as a data transceiver.

[0124] See also Figure 7 In an optional embodiment, the communication data sent by the data transmitting end CTL to the controller 400 comes from a mobile terminal such as a mobile phone or a tablet, and the communication data is forwarded from the data transmitting end CTL to the controller 400. Therefore, the communication module of the data transmitting end CTL needs to realize wireless communication with the mobile terminal. In addition, the data transmitting end CTL can also extract the target parameter information of each photovoltaic component PV1-PVN from the controller 400 based on its communication function, such as extracting the component operating voltage and component operating current of each photovoltaic component PV1-PVN. Similarly, the data transmitting end CTL can also extract the target parameter information of each voltage converter H1-HN from the controller 400 based on its communication function, such as extracting the input voltage and output voltage, the input current and output current of each voltage converter H1-HN. In essence, the extracted information can come from voltage sensors 111 and 113, current sensors 112 and 114, etc. Feedback of various target parameters to the mobile terminal will be very beneficial to monitor the photovoltaic components and voltage converters at the mobile terminal.

[0125] See also Figure 7 In an optional embodiment, the communication data sent by the data sending terminal CTL to the controller 400 is from the Internet or a local area network, and the communication data is forwarded from the data sending terminal CTL to the controller 400. Therefore, the communication module of the data sending terminal CTL needs to realize network communication with the Internet or the local area network. The data sending terminal CTL can extract the target parameter information of each photovoltaic component PV1-PVN from the controller 400 based on its communication function, and it can also extract the target parameter information of each voltage converter H1-HN from the controller 400 based on its communication function. For example, the input voltage and output voltage, input current and output current of each voltage converter H1-HN are extracted, for example, the component operating voltage and component operating current of each photovoltaic component PV1-PVN are extracted. Feedback of various target parameters to the Internet or the local area network will be very beneficial for monitoring the photovoltaic components and voltage converters at the network end.

[0126] See also Figure 7 In an optional embodiment, the data transmission terminal CTL is integrated in the power converter 100 and exists as an auxiliary unit of the power converter 100. The data transmission terminal CTL may be integrated in the voltage converter and exists as an auxiliary unit of each of the voltage converters H1-HN. The data transmission terminal CTL may also exist independently.

[0127] See also Figure 7 In an optional embodiment, the data transmission terminal CTL is abandoned, and the controller 400 corresponding to each of the voltage converters H1-HN is equipped with a wireless communication module such as 2G-6G locally, and the controller 400 can interact with the mobile terminal or the network. The communication data is directly sent to the controller 400 by the mobile terminal or the network. The controller 400 can also conveniently directly feed back the target parameter information of each photovoltaic module PV1-PVN and the target parameter information of each voltage converter H1-HN to the mobile terminal or the network.

[0128] See also Figure 7 In an optional embodiment, the data sending terminal CTL can also be used as a control device for executing the rapid shutdown of photovoltaic components. Rapid shutdown of photovoltaic components is an essential measure to ensure the safety of photovoltaic systems in some countries. For example, the National Electrical Code (NEC) of the United States requires that the photovoltaic system have a "photovoltaic hazard control system" to ensure that the photovoltaic system is in a controllable state in critical situations. Usually, a "photovoltaic hazard control system" is used to implement component-level shutdown, so that the voltage within the boundary range is reduced to below 80V within 30S after the rapid shutdown is initiated. The data sending terminal CTL can be regarded as a photovoltaic hazard control system. The data sending terminal CTL can be manually operated to send a shutdown instruction to the controller 400. The shutdown instruction is transmitted to the controller 400 in the form of the aforementioned various types of communication data. When the controller 400 receives the shutdown instruction, it can respond to the shutdown instruction and Figure 5 The switches S1-S4 are all driven to be turned off.

[0129] See also Figure 7 In an optional embodiment, any voltage converter such as HN is equipped with a controller 400 for operating the voltage converter HN to perform voltage conversion. Figure 5 , the controller 400 changes the actual conversion ratio R of the voltage converter HN when it is working. ON To reduce R ON and Rob_VN. For example, the controller can change the actual conversion ratio R by changing the duty cycle of the voltage converter HN. ON If the voltage converter HN works in the buck state, the duty cycle of the Buck circuit will be changed; if the voltage converter HN works in the boost state, the duty cycle of the Boost circuit will be changed; if the voltage converter HN works in the buck-boost state, the buck duty cycle and boost duty cycle of the Buck-Boost circuit will be changed. Reduce R' ON The same can be said for the difference between and Rob_IN.

[0130] See also Figure 7 In an optional embodiment, in combination with Figure 5 , the size of the target conversion ratio set as programmable received by the controller 400 is adjustable. For example, the size of the target conversion ratio Rob_VN is changed in the communication data sent by the data sending end CTL to the controller 500, and the controller 400 uses the updated Rob_VN to control the corresponding voltage converter HN to optimize the power of the photovoltaic module PVN. The size of the target conversion ratio Rob_VN is changed in the communication data sent by the mobile end to the controller 500, which also achieves the purpose of Rob_VN being programmable.

[0131] See also Figure 7 In an optional embodiment, the voltage converter HN is used to convert the electric energy captured from the photovoltaic module PVN into the output power of the voltage converter HN itself. The specified output parameter of the voltage converter HN is compared with the specified input parameter to obtain the actual conversion ratio, such as R ON (or R' ON ). The power optimization of the photovoltaic module is implemented in a way to reduce the difference between the actual conversion ratio and the preset target conversion ratio, such as Rob_VN (or Rob_IN). There are various schemes to reduce the difference. For example, the calculation of the optimized power SP can be implemented for the photovoltaic module PVN. The diversity of the scheme to reduce this difference is reflected in assuming that SP=pow×(1-abs(Rob_VN-R ON )×k) to reduce the difference between the actual conversion ratio and the preset target conversion ratio, that is, to reduce Rob_VN and R ON To achieve the optimization purpose, the controller can perform the optimization calculation of the power SP. For example, the power SP of the photovoltaic module PVN can be optimized. The optimization calculation formula needs to be slightly modified. Assume that SP = pow × (1-abs (Rob_IN-R' ON )×k') to reduce the difference between the actual conversion ratio and the preset target conversion ratio, that is, to reduce Rob_IN and R' ON The symbol abs in the above formula represents the absolute value, and pow represents the power of the photovoltaic module PVN. PVN *V PVN The values ​​of the coefficients k and k' that appear respectively are different, and they represent preset coefficient values ​​that can be set as needed, for example, based on experience.

[0132] See also Figure 7 , in the transformed form, SP = pow × abs (J - abs (Rob_VN - R ON )×k) to reduce the difference between the actual conversion ratio and the preset target conversion ratio, that is, to reduce Rob_VN and R ONThe optimization calculation formula is also slightly modified to adapt to SP = pow × abs (J - abs (Rob_IN - R' ON )×k') to reduce the difference between the actual conversion ratio and the preset target conversion ratio, that is, to reduce Rob_IN and R' ON The non-zero preset constant J in the above formula can be set as needed, for example, 1 is just one of the options.

[0133] See also Figure 7 In an optional embodiment, the power SP of the photovoltaic module PVN is optimized. The diversity of the scheme to reduce this difference is reflected in that, assuming SP = pow × (1 - (Rob_VN - R ON ) 2 ×α) to reduce the difference between the actual conversion ratio and the preset target conversion ratio, that is, to reduce Rob_VN and R ON To achieve the optimization purpose, the controller can perform the optimization calculation of the power SP. For example, the power SP of the photovoltaic module PVN can be optimized. The formula for optimizing the calculation can be slightly modified adaptively. It can be assumed that SP=pow×(1-(Rob_IN-R' ON ) 2 ×β) to reduce the difference between the actual conversion ratio and the preset target conversion ratio, that is, to reduce Rob_IN and R' ON The difference is achieved to achieve the optimization purpose. The values ​​of coefficients α and β appearing in the above formula are different, and they represent preset coefficient values ​​that can be set as needed. The power optimization of photovoltaic modules is implemented by reducing the difference between the actual conversion ratio and the target conversion ratio. Another meaning is that the power of photovoltaic modules can be increased (or maximized) by reducing the difference between the actual conversion ratio and the target conversion ratio. The various schemes for tracking SP maximization mentioned above provide specific examples of implementing power optimization for photovoltaic modules.

[0134] See also Figure 7 , in the transformed form, SP = pow × abs (T - (Rob_VN - R ON ) 2 ×α) to reduce the difference between the actual conversion ratio and the preset target conversion ratio, that is, to reduce Rob_VN and R ON The difference is achieved by optimizing the calculation formula. The calculation formula is slightly modified adaptively, assuming SP = pow × abs (T - (Rob_IN - R' ON ) 2 ×β) to reduce the difference between the actual conversion ratio and the preset target conversion ratio, that is, to reduce Rob_IN and R' ON The non-zero preset constant T in the above formula can be set as needed, for example, 1 is just one of the options.

[0135] See also Figure 7 In an optional embodiment, the power SP of the photovoltaic module PVN is optimized. The diversification of the schemes for reducing such differences is reflected in the following: SP=pow×(1-abs((Rob_VN-R ON ) M )×α1) optimization, reducing the difference between the actual transformation ratio and the preset target transformation ratio, that is, reducing Rob_VN and R ON To achieve the optimization purpose, the controller can perform the optimization calculation of the power SP. For example, the power SP of the photovoltaic module PVN can be optimized. The formula for optimizing the calculation can be slightly modified to adapt SP=pow×(1-abs((Rob_IN-R' ON ) M )×β1) optimization, reducing the difference between the actual conversion ratio and the preset target conversion ratio, that is, reducing Rob_IN and R' ON Difference, to achieve the optimization purpose. The values ​​of the coefficients α1 and β1 appearing in the above formula are different. The non-zero odd superscript M represents the power symbol or several powers. α1 and β1 represent preset coefficient values ​​that can be set as needed. In an optional embodiment, the above-mentioned optimized power SP can use schemes such as the conductance increment method or the perturbation observation method to track its maximum value. If the previous actual conversion ratio corresponds to the previous SP value, if the previous actual conversion ratio is increased to the next actual conversion ratio, the next actual conversion ratio corresponds to the next SP value. Assuming that the perturbation observation method is used and the next SP value is increased compared to the previous SP value, then continue to increase the actual conversion ratio, otherwise change the disturbance direction, such as reducing the actual conversion ratio, and repeat this process until the optimized power SP is maximized.

[0136] See also Figure 7 , in the transformed form, SP = pow × abs (Y - abs ((Rob_VN - R ON ) M )×α1) optimization, reducing the difference between the actual transformation ratio and the preset target transformation ratio, that is, reducing Rob_VN and R ON The difference is achieved by optimizing the calculation formula. The calculation formula is slightly modified to SP = pow × abs (Y - abs ((Rob_IN - R' ON ) M )×β1) optimization, reducing the difference between the actual conversion ratio and the preset target conversion ratio, that is, reducing Rob_IN and R' ON The difference is achieved to achieve the optimization purpose. The non-zero preset constant Y in the above formula can be set as needed, for example, 1 is just one of the options. It can be seen that reducing the difference between the actual conversion ratio and the target conversion ratio, optimizing the power of photovoltaic modules, and maximizing SP are diverse.

[0137] See also Figure 2In an optional embodiment, when the voltage converter such as HN is actually running, it does not know what the conversion ratio is required for the corresponding photovoltaic module PVN or itself to be at maximum power output, because the voltage converter does not actually perform MPPT. Therefore, the tracking method for the voltage converter HN to adjust SP can be implemented in the above or more ways, which have a common goal: to make the actual conversion ratio (such as R ON or R' ON ) is close to or equal to the target conversion ratio. Or the actual conversion ratio is made close to or equal to the conversion ratio required when the photovoltaic module PVN is at maximum power output, for example, by means of the MPPT function of the power converter 100.

[0138] See also Figure 8 , the shadow occurs at the PVN position of the PV module, which is recorded as Part_B. The positions without shadow are the PV1 to PV(N-1) positions of the PV modules, which are recorded as Part_A. In reality, Part_B usually occurs not only at the PVN position of the PV module, and Part_A is usually much less than the PV1 to PV(N-1) positions of the PV modules. This example divides the shadow into Part_A and Part_B for the sake of explanation. The uncertainty of external shadowing factors causes the maximum output power and the corresponding voltage of the maximum power point to change with the changes of external factors.

[0139] See also Figure 8 , the power converter 100 converts the string current I N And the string voltage V BUS Set at its maximum power point, that is, perform MPPT, the unshaded PV modules in a single string (such as Part_A) are at their own maximum power point, and the PV modules in a single string that are shaded (Part_B) are at non-maximum power points. When the power characteristics of the PV modules PV1-PVN in the PV system are inconsistent, the PV system may not be operating at the theoretical maximum power point, because the voltage converters H1-H(N-1) or power optimizers corresponding to the unshaded PV modules can all operate near their maximum power points, and the voltage converters HN or power optimizers corresponding to the shaded PV modules do not operate at the maximum power point. This is a feature of this article, but the total system power is still the result of optimization.

[0140] See also Figure 8In an optional embodiment, the power optimizer includes a DC / DC converter. The DC / DC converter can be, for example, the voltage converter HN mentioned above. The DC / DC converter is used to implement power optimization for the photovoltaic component PN and also sets a voltage-based target conversion ratio for the DC / DC converter, for example, the ratio of the expected output voltage to the input voltage is the target conversion ratio. In the normal working stage of the DC / DC converter, its output voltage is compared with the input voltage to obtain an actual conversion ratio. Based on making the actual conversion ratio closer to the target conversion ratio, the power of the photovoltaic component is increased by reducing the difference between the actual conversion ratio and the target conversion ratio, that is, the power optimization of the photovoltaic component is implemented. A further limiting condition of this example is that the multi-stage DC / DC converters are connected in series, the power converter 100 performs power conversion on the output power provided by the multi-stage DC / DC, and the power converter 100 has a maximum power point tracking MPPT function.

[0141] See also Figure 5 , if the DC / DC converter is set based on the target conversion ratio of the voltage, such as Figure 5 The voltage sensors 111 and 113 shown collect input voltage and output voltage respectively, and the controller 400, such as a microprocessor, calculates the actual conversion ratio of the output voltage and the input voltage through the voltage data collected by these voltage sensors 111 and 113. For example, the microprocessor collects the working current of the photovoltaic component through the current sensor 112, and calculates the power of the photovoltaic component PVK according to the working current and working voltage of the photovoltaic component PVK. When driving the voltage converter HK, the microprocessor can adjust the actual conversion ratio of its output voltage and input voltage to tend to the target conversion ratio.

[0142] See also Figure 8 In an optional embodiment, the power optimizer includes a DC / DC converter. The DC / DC converter can be, for example, the voltage converter HN mentioned above. The DC / DC converter is used to implement power optimization for the photovoltaic component PN and also sets a current-based target conversion ratio for the DC / DC converter, for example, the ratio of the expected output current to the input current is the target conversion ratio. During the normal working phase of the DC / DC converter, the actual conversion ratio is obtained by comparing its output current with the input current. Based on making the actual conversion ratio closer to the target conversion ratio, the power of the photovoltaic component is increased by reducing the difference between the actual conversion ratio and the target conversion ratio, that is, the power optimization of the photovoltaic component is implemented. A further limiting condition of this example is that the multi-stage DC / DC converters are connected in series, the power converter 100 performs power conversion on the output power provided by the multi-stage DC / DC, and the power converter 100 has a maximum power point tracking MPPT function.

[0143] See also Figure 5 , if the DC / DC converter is set based on the target conversion ratio of the current, such as Figure 5 The current sensors 112 and 114 shown collect input current and output current respectively, and the controller 400, such as a microprocessor, calculates the actual conversion ratio of the output current and the input current through the current data collected by these current sensors 112 and 114. For example, the microprocessor collects the working voltage of the photovoltaic component through the voltage sensor 111, and calculates the power of the photovoltaic component PVK according to the working current and working voltage of the photovoltaic component PVK. When driving the voltage converter HK, the microprocessor can adjust the actual conversion ratio of its output current and input current to tend to the target conversion ratio.

[0144] See also Fig. 9 In an optional embodiment, the photovoltaic components PV1-PVN corresponding to the voltage converters H1-HN can be regarded as the first parallel groups, and the photovoltaic components PV1-PVK corresponding to the voltage converters H1-HK can be regarded as the second parallel groups. These two or more parallel groups not shown are connected in parallel, so the power converter 100 can be powered by a single parallel group or multiple parallel parallel groups. Figure 8 Similarly, power optimization can be implemented for photovoltaic modules as long as the difference between the actual conversion ratio and the preset target conversion ratio is reduced as much as possible. Mismatches in photovoltaic systems, such as the inability of power optimizers to work completely in unison, and even the mutual influence of power optimizers, as well as factors such as shadows, may cause all power optimizers to not work at their target conversion ratios, or only a very small number of power optimizers can work at their target conversion ratios, but this does not affect the power optimization implemented for individual photovoltaic modules and the power optimization implemented for the entire photovoltaic system. Therefore, power optimization of photovoltaic modules is implemented in a manner that reduces the difference between the actual conversion ratio and the preset target conversion ratio, which means that the situation where the actual conversion ratio is not equal to the preset target conversion ratio is allowed. In the optional example, the difference does not exceed a predetermined value determined in advance or is within a predetermined range determined in advance, and it is considered that power optimization of photovoltaic modules is achieved. Or in other optional embodiments, the actual conversion ratio and the preset target conversion ratio currently have a previous difference, and after the actual conversion ratio continues to approach the preset target conversion ratio, they have a latter difference, and the power of the photovoltaic module under the latter difference is larger than the power of the photovoltaic module under the former difference, and it is considered that the power optimization of the photovoltaic module is achieved. Based on the condition of the former difference, the actual conversion ratio continues to approach the preset target conversion ratio, so the latter difference is smaller than the former difference. The above examples are actually in line with the main purpose of this article, such as reducing the difference between the actual conversion ratio and the preset target conversion ratio (that is, the actual conversion ratio approaches the preset target conversion ratio), optimizing the power of the photovoltaic module, or increasing the power of the photovoltaic module.

[0145] See also Fig. 9 In an optional embodiment, the multi-level voltage converters H1-HN are connected in parallel, and the power converter 100 still performs power conversion on the output power provided by the multi-level voltage converters H1-HN. As mentioned above, the power converter 100 has the maximum power tracking MPPT function, and the power converter 100 performs maximum power tracking on the multiple photovoltaic components PV1-PVN corresponding to the parallel multi-level voltage converters H1-HN as a whole. This is different from the way the multi-level voltage converters are connected in series as mentioned above. In addition, the voltage converters H1-HK are also connected in parallel, and the power converter 100 still performs power conversion on the output power provided by the multi-level voltage converters H1-HK. As mentioned above, the power converter 100 has the maximum power tracking MPPT function, and the power converter 100 performs maximum power tracking on the multiple photovoltaic components PV1-PVK corresponding to the parallel multi-level voltage converters H1-HK as a whole. In the parallel relationship, the two output ends of each voltage converter are respectively coupled to the bus LA and the bus LB.

[0146] 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 power optimizer, characterized in that: include: A voltage converter is used to convert the electric energy captured from the photovoltaic module into output power. The actual conversion ratio is obtained by comparing the specified output parameters of the voltage converter with the specified input parameters. The actual conversion ratio is brought closer to a preset target conversion ratio to optimize the power of the photovoltaic module.

2. The power optimizer according to claim 1, characterized in that: The specified output parameter and the specified input parameter are an output voltage and an input voltage, respectively.

3. The power optimizer according to claim 1, characterized in that: The specified output parameter and the specified input parameter are output current and input current, respectively.

4. The power optimizer according to claim 1, characterized in that: The voltage converter is selected from any one of a buck converter, a boost converter, and a buck-boost converter.

5. The power optimizer according to claim 1, characterized in that: The multi-level voltage converters are connected in series or in parallel, and a power converter performs power conversion on the output power provided by the multi-level voltage converters. The power converter has a maximum power tracking function, and the power converter performs maximum power tracking on a plurality of photovoltaic modules corresponding to the multi-level voltage converters connected in series or in parallel as a whole.

6. The power optimizer according to claim 5, characterized in that: The power converter includes an inverter that performs direct current to alternating current conversion, or includes a direct current converter that performs direct current to direct current conversion.

7. The power optimizer according to claim 5, characterized in that: A plurality of photovoltaic modules corresponding to a group of multi-level voltage converters connected in series is regarded as a group string; The power converter is powered by a single string or multiple strings connected in parallel.

8. The power optimizer according to claim 7, characterized in that: The power converter sets the string current and string voltage of any single string at its maximum power point.

9. The power optimizer according to claim 7, characterized in that: When a plurality of parallel strings supply power to the power converter, target conversion ratios of voltage converters corresponding to different strings with unequal numbers of photovoltaic components are also set to be different.

10. The power optimizer according to claim 9, characterized in that: The target conversion ratio of the voltage converter corresponding to the string with a small number of photovoltaic components is set to be larger than the target conversion ratio of the voltage converter corresponding to the string with a large number of photovoltaic components.

11. The power optimizer according to claim 7, characterized in that: Among the multi-level voltage converters corresponding to a single string, target conversion ratios of different voltage converters are set to be different or the same.

12. A method for realizing power optimization, characterized in that: A voltage converter is used to convert the electrical energy captured from the photovoltaic module into output power. The specified output parameters of the voltage converter are compared with the specified input parameters to obtain the actual conversion ratio. The power of the photovoltaic module is optimized by bringing the actual conversion ratio closer to the preset target conversion ratio.

13. The method according to claim 12, characterized in that: The designated output parameter and the designated input parameter are an output voltage and an input voltage, respectively, or the designated output parameter and the designated input parameter are an output current and an input current, respectively.

14. The method according to claim 12, characterized in that: The multi-level voltage converters are connected in series or in parallel, and a power converter performs power conversion on the output power provided by the multi-level voltage converters. The power converter has a maximum power tracking function, and the power converter performs maximum power tracking on a plurality of photovoltaic modules corresponding to the multi-level voltage converters connected in series or in parallel as a whole.

15. The method according to claim 14, characterized in that: A plurality of photovoltaic modules corresponding to a group of multi-level voltage converters connected in series is regarded as a group string; The power converter is powered by a single string or multiple strings connected in parallel.

16. The method according to claim 14, characterized in that: The power converter sets the string current and string voltage of any single string at its maximum power point.

17. The method according to claim 12, characterized in that: The voltage converter is provided with a controller for operating the voltage converter to perform voltage conversion. The controller adjusts the actual conversion ratio when the voltage converter is working and controls the actual conversion ratio to approach a preset target conversion ratio.

18. The method according to claim 17, characterized in that: The size of the target transformation ratio set as programmable and received by the controller is adjustable.

19. A power optimizer, characterized in that: include: A DC / DC converter is used to implement power optimization for photovoltaic modules. A voltage-based target conversion ratio is set for the DC / DC converter, wherein an actual conversion ratio is obtained by comparing the output voltage of the DC / DC converter with the input voltage during operation, and the actual conversion ratio approaches the preset target conversion ratio to implement power optimization for the photovoltaic modules.

20. The power optimizer according to claim 19, characterized in that: The multi-stage DC / DC converters are connected in series or in parallel, and a power converter performs power conversion on the output power provided by the DC / DC voltage converter. The power converter has a maximum power point tracking function, and the power converter performs maximum power point tracking on a plurality of photovoltaic modules corresponding to the multi-stage DC / DC converters connected in series or in parallel as a whole.

21. The power optimizer according to claim 20, characterized in that: A plurality of photovoltaic modules corresponding to a group of multi-level DC / DC converters connected in series are regarded as a string, and power is supplied to the power converter by a single string or a plurality of parallel strings.

22. A power optimizer, characterized in that: include: A DC / DC converter is used to optimize the power of a photovoltaic module. A target conversion ratio based on current is set for the DC / DC converter, wherein an actual conversion ratio is obtained by comparing the output current and input current of the DC / DC converter during operation, and the actual conversion ratio approaches a preset target conversion ratio to optimize the power of the photovoltaic module.

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