CN108199681B

CN108199681B - Photovoltaic module power optimization circuit and communication method thereof

Info

Publication number: CN108199681B
Application number: CN201611118782.4A
Authority: CN
Inventors: 应剑东; 张永
Original assignee: Fonrich Shanghai New Energy Technology Co ltd
Current assignee: Fonrich Shanghai New Energy Technology Co ltd
Priority date: 2016-12-08
Filing date: 2016-12-08
Publication date: 2020-10-09
Anticipated expiration: 2036-12-08
Also published as: CN108199681A

Abstract

The invention mainly relates to a photovoltaic module power optimization circuit, which adopts a scheme that a multi-stage power optimization circuit is used in each single photovoltaic module, the photovoltaic module is provided with multi-stage voltage conversion circuits with the number consistent with that of battery strings of the photovoltaic module, and in the multi-stage voltage conversion circuit corresponding to any one photovoltaic module, each stage of the voltage conversion circuit is used for independently performing maximum power tracking on one corresponding battery string in any one photovoltaic module. The power optimization circuit can transmit data outwards in a power carrier signal mode, and besides each photovoltaic cell string in each photovoltaic module is enabled to correspondingly perform maximum power tracking through one power optimization circuit, the power optimization circuit also integrates a communication function.

Description

Photovoltaic module power optimization circuit and communication method thereof

Technical Field

The invention mainly relates to the technical field of photovoltaic power generation, in particular to a scheme that a multi-stage power optimization circuit is used in each single photovoltaic module, the power optimization circuit can send data to the outside in a power carrier signal mode, each photovoltaic cell string in each photovoltaic module is enabled to be correspondingly subjected to maximum power tracking by one power optimization circuit, and a communication function is integrated, so that the output power of the whole photovoltaic module is optimized and data communication is realized.

Background

With the irreproducibility of traditional chemical energy sources such as petroleum, coal, natural gas and the like and the negative environmental problems caused by the chemical energy sources becoming serious day by day, the search for inexhaustible and repeated renewable energy sources to replace traditional chemical energy sources with limited resources and environmental pollution becomes an important proposition which is urgently needed to be solved in the field of new energy sources. The technological development based on new technology and new material makes the renewable energy resource developed and utilized modernized, such as solar energy, geothermal energy, wind energy, ocean energy, biomass energy, nuclear fusion energy, etc. and the new energy resource with environment protection and sustainable development is applied more and more widely in various countries and regions in the world. Because the new energy of photovoltaic power generation has the advantages of cleanness, safety, reliability, low operation cost, simple daily maintenance, availability at any place and the like, the photovoltaic power generation becomes a novel industry which is generally concerned and intensively developed by countries in the world, the photovoltaic power generation industry is rapidly developed in the world, and particularly plays an indispensable role in solving the problems of energy shortage and power utilization in remote areas.

In the current photovoltaic power generation system, in order to ensure that the whole power generation system runs more safely and reliably, various potential threats can be preferably discovered in time, for example, a hot spot effect caused by shadow shielding is a negative threat, and some batteries may be converted from a power supply to a load to cause a battery panel to be heated to be burnt, so that monitoring of working parameters such as voltage, current, power, temperature and the like of the photovoltaic batteries is an important link in the photovoltaic power generation system. The working parameter monitoring of the photovoltaic cell adopts a power line carrier as a communication means in practical application occasions, the parameters of the photovoltaic cell can be easily transmitted to a power line which provides photovoltaic voltage by the photovoltaic cell as communication data by means of the power line carrier, and then the real-time parameters of the photovoltaic cell can be acquired by decoding a carrier signal from the power line. Unlike a common data communication line, which originally aims at transmitting power rather than data, a power line is not ideal for data communication, and is a very unstable transmission channel, which is characterized by significant noise and severe signal attenuation. In order to overcome the problem of instability, the power line broadband carrier technology adopts modulation technologies such as spread spectrum and orthogonal frequency division multiplexing, and the fact proves that the multi-carrier orthogonal frequency division multiplexing is an effective method for solving the problem of transmission interference on a power line so far, and the power line broadband communication adopts the orthogonal frequency division multiplexing technology to effectively resist multipath interference so that interfered signals can still be reliably received. The method for improving the reliability of the signal by sampling the voltage level of the photovoltaic cell and the carrier is only one aspect, but in the case of simultaneous application of the photovoltaic cell and the carrier, since the voltage level of the photovoltaic cell itself is greatly changed by the ambient temperature and the light radiation intensity, the distortion of the carrier signal itself propagation on the power line and the characteristic of the cell that the output characteristic is easy to fluctuate are mixed together, so that the actual carrier signal expected to be captured by the receiving end is not accurate, the error rate is high, and the voltage superposed on the photovoltaic cell string group is also interfered by the carrier, so that the actual voltage on the whole string group may not be within the expected range.

In current photovoltaic power optimization approaches, optimization is almost always performed at the photovoltaic module level, which is generally an optimization module to optimize one or more photovoltaic modules, but in practice each photovoltaic module will usually comprise a plurality of strings of cells connected in series by cells, and according to the prior art, optimization at the photovoltaic module level means that each individual string of cells is not individually optimized. When the consistency of single batteries of the same string of batteries is poor due to problems of manufacturing processes and the like, or when partial batteries cannot normally generate power due to external shadow shielding events such as dirt, cloud layers and the like, the efficiency loss of the whole string of photovoltaic batteries is serious, and when the number of connected photovoltaic module arrays of inverters, particularly centralized inverters is large, the battery panels of all strings of batteries cannot operate at the maximum power point of the inverters, so that the great loss of generated power is caused under the conditions, and the generation of the photovoltaic modules is avoided. The power optimization circuit described in the following of the present application mainly solves or alleviates these problems, and implements power optimization at a string level rather than a module level to perform active power optimization for each photovoltaic string, and introduces maximum power point tracking to ensure maximum power optimization for each photovoltaic module. In addition, monitoring of working parameters of photovoltaic modules is an important link, in a large photovoltaic power station or a distributed power station, criteria for evaluating the quality of each photovoltaic module refer to parameters of the photovoltaic module, such as voltage, current, power, temperature and the like, and how to capture the parameters of the photovoltaic modules and reliably send the parameters from the module side to achieve communication is also one of the problems to be solved.

Disclosure of Invention

The invention discloses a photovoltaic module power optimization circuit, wherein any one photovoltaic module is provided with a plurality of battery strings, and each photovoltaic module is provided with a plurality of voltage conversion circuits with the number consistent with that of the battery strings; in the multistage voltage conversion circuit corresponding to any one photovoltaic module: each stage of voltage conversion circuit is used for independently performing maximum power tracking on a corresponding battery string in any one photovoltaic module; and the multi-stage voltage conversion circuits corresponding to any one photovoltaic module are arranged to be connected in parallel, so that the voltages output by the multi-stage voltage conversion circuits are output to an output capacitor corresponding to the any one photovoltaic module together.

The photovoltaic module power optimization circuit is formed by connecting a plurality of photovoltaic modules in series to form a battery string, and the total voltage of each battery string is equal to the superposition value of the voltages of the output capacitors corresponding to the photovoltaic modules connected in series.

In the power optimization circuit for photovoltaic modules, the multi-stage voltage conversion circuit corresponding to any one photovoltaic module comprises: the first input node and the second input node of each voltage conversion circuit are correspondingly and respectively connected to the positive electrode and the negative electrode of a corresponding battery string in any one photovoltaic assembly; and the first output node and the second output node of each voltage conversion circuit are correspondingly connected to the first end and the second end of one output capacitor corresponding to any one photovoltaic module respectively.

The photovoltaic module power optimization circuit is a boost voltage conversion circuit, an inductor and a first switch are connected in series between a first input node and a first output node of each voltage conversion circuit, and a second input node is coupled to a second output node, wherein one end of the inductor is coupled to the first input node, a first switch is arranged between the other end of the inductor, which is opposite to the first input node, and the first output node, and a second switch is arranged between an interconnection node between the inductor and the first switch and the second input node or the second output node.

In the photovoltaic module power optimization circuit, a disconnection module is arranged between the first input node of each voltage conversion circuit and the positive electrode of the battery string or between the second input node of each voltage conversion circuit and the negative electrode of the battery string; or a circuit breaking module is arranged between the first output node of each voltage conversion circuit and the first end of the output capacitor or between the second output node of each voltage conversion circuit and the second end of the output capacitor.

In the photovoltaic module power optimization circuit, a preset voltage conversion circuit is defined in a multi-stage voltage conversion circuit corresponding to any one photovoltaic module; wherein a circuit breaking module is arranged between a first output node of the preset voltage conversion circuit and a first end of the output capacitor; in the multi-stage voltage conversion circuit corresponding to any one photovoltaic module, the first output nodes of other voltage conversion circuits except the preset voltage conversion circuit are coupled to the first output node of the preset voltage conversion circuit; or a circuit breaking module is arranged between a second output node of the preset voltage conversion circuit and the second end of the output capacitor; in the multi-stage voltage conversion circuit corresponding to any one photovoltaic module, the second output nodes of the other voltage conversion circuits except the preset voltage conversion circuit are coupled to the second output node of the preset voltage conversion circuit.

In the photovoltaic module power optimization circuit, a preset voltage conversion circuit is defined in a multi-stage voltage conversion circuit corresponding to any one photovoltaic module; wherein a disconnection module is arranged between a second input node of the preset voltage conversion circuit and a negative electrode of a battery string uniquely corresponding to the preset voltage conversion circuit; and in the multi-stage voltage conversion circuit corresponding to any one photovoltaic module, the second output nodes of the other voltage conversion circuits except the preset voltage conversion circuit are connected to the negative electrode of the battery string uniquely corresponding to the other voltage conversion circuits through the circuit breaking module.

In the photovoltaic module power optimization circuit, a plurality of photovoltaic modules are connected in series to form a battery pack string, and the output capacitors of the photovoltaic modules in each battery pack string are connected in series; a carrier sending module connected with the output capacitor in parallel is connected between the first end and the second end of one output capacitor corresponding to each photovoltaic module, and a control switch connected with the output capacitor in series is arranged between the first end and the second end; at the stage that a carrier sending module corresponding to a specified photovoltaic module sends a carrier signal to a transmission line which connects all output capacitors in a battery string in series, control switches which are connected with the output capacitors corresponding to the specified photovoltaic module in series are in an off state, and control switches corresponding to other photovoltaic modules except the specified photovoltaic module in the battery string are in an on state to form a transmission path of the carrier signal.

In the photovoltaic module power optimization circuit, a plurality of photovoltaic modules are connected in series to form a battery string, and output capacitors corresponding to the photovoltaic modules in each battery string are connected in series through a transmission line; a control switch connected in series with an output capacitor is arranged between a first end and a second end of the output capacitor of the multi-level voltage conversion circuit corresponding to each photovoltaic module; when the control switch configured by the multi-level voltage conversion circuit corresponding to any one photovoltaic module is switched on, the multi-level voltage conversion circuit corresponding to the any one photovoltaic module is in a first working mode of converting and outputting the received voltage; when the control switch configured by the multi-level voltage conversion circuit corresponding to any one photovoltaic module is turned off, any one appointed circuit in the multi-level voltage conversion circuit corresponding to any one photovoltaic module is in a second working mode of coupling excitation pulses jumping between high and low levels to the transmission line as a carrier signal; wherein the excitation pulse originates from: the pulse width modulation signal used for driving the specified circuit forces the voltage output by the specified circuit to have step change along with the frequency of the pulse width modulation signal, and the output step voltage is regarded as an excitation pulse.

Another embodiment of the present application discloses a communication method of the power optimization circuit of photovoltaic modules according to the above, wherein a plurality of photovoltaic modules are connected in series to form a battery string, the output capacitors of the photovoltaic modules in each battery string are connected in series, a carrier transmitting module connected in parallel with the output capacitor is connected between the first end and the second end of an output capacitor configured for each photovoltaic module, and a control switch connected in series with the output capacitor is arranged between the first end and the second end; when a carrier sending module configured by any one appointed photovoltaic module sends a carrier signal to a transmission line which connects all output capacitors in a battery string in series to execute communication: one processor of the designated photovoltaic module configuration drives the control switches connected in series with the output capacitors corresponding to the designated photovoltaic module to be in an off state, and the processors of the other photovoltaic modules except the designated photovoltaic module in the battery string, which are respectively configured, drive the corresponding control switches to be in an on state, thereby forming a broadcasting path of the carrier signal.

In the above communication method, the voltage conversion circuit is a BOOST voltage conversion circuit and is a multi-stage voltage conversion circuit corresponding to any one of the photovoltaic modules: the first input node and the second input node of each voltage conversion circuit are correspondingly and respectively connected to the positive electrode and the negative electrode of a corresponding battery string in any one photovoltaic assembly; and the first output node and the second output node of each voltage conversion circuit are correspondingly connected to the first end and the second end of one output capacitor corresponding to any one photovoltaic module respectively.

In the above communication method, a disconnection module is provided between the first input node of each voltage conversion circuit and the positive electrode of the battery string uniquely corresponding to the voltage conversion circuit, or a disconnection module is provided between the second input node of each voltage conversion circuit and the negative electrode of the battery string uniquely corresponding to the voltage conversion circuit; or a circuit breaking module is arranged between the first output node of each voltage conversion circuit and the first end of the output capacitor, or a circuit breaking module is arranged between the second output node of each voltage conversion circuit and the second end of the output capacitor.

In the communication method, a preset voltage conversion circuit is defined in a multi-stage voltage conversion circuit corresponding to any one photovoltaic module; wherein a circuit breaking module is arranged between a first output node of the preset voltage conversion circuit and a first end of the output capacitor; in the multi-stage voltage conversion circuit corresponding to any one photovoltaic module, the first output nodes of other voltage conversion circuits except the preset voltage conversion circuit are coupled to the first output node of the preset voltage conversion circuit; or a circuit breaking module is arranged between a second output node of the preset voltage conversion circuit and the second end of the output capacitor; in the multi-stage voltage conversion circuit corresponding to any one photovoltaic module, the second output nodes of the other voltage conversion circuits except the preset voltage conversion circuit are coupled to the second output node of the preset voltage conversion circuit.

Another embodiment of the present application discloses a communication method of a power optimization circuit of photovoltaic modules according to the above, wherein a plurality of photovoltaic modules are connected in series to form a battery string, output capacitors corresponding to the plurality of photovoltaic modules in each battery string are connected in series with each other through a transmission line, and a control switch connected in series with one output capacitor is arranged between a first end and a second end of the output capacitor of the multi-stage voltage conversion circuit corresponding to each photovoltaic module; when the multi-stage voltage conversion circuit configured by any one specified photovoltaic module sends a carrier signal to the transmission line to perform communication: one processor of the appointed photovoltaic component configuration drives the control switch connected with the output capacitor corresponding to the appointed photovoltaic component in series at least once to be switched off, and the processors of the other photovoltaic components except the appointed photovoltaic component in the battery pack string are respectively configured to drive the corresponding control switch to be in a switching-on state, so that a propagation path of the carrier signal is formed; when the control switch arranged on the multi-stage voltage conversion circuit corresponding to the specified photovoltaic module is turned off, any specified/preset circuit in the multi-stage voltage conversion circuit corresponding to the specified photovoltaic module couples excitation pulses jumping between high and low levels onto the transmission line as a carrier signal, and the excitation pulses are derived from: the pulse width modulation signal used for driving the specified/preset circuit forces the voltage output by the specified circuit to have step change along with the frequency of the pulse width modulation signal, and the output step voltage is regarded as an excitation pulse.

Drawings

The features and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the following drawings:

fig. 1 is a schematic diagram of an example of a photovoltaic module configured with an associated optimization circuit to form a battery string.

Fig. 2 is an exemplary schematic diagram of an optimization circuit for any photovoltaic module with a multi-stage voltage conversion circuit.

Fig. 3 is an exemplary schematic diagram of a voltage conversion circuit using BOOST.

FIG. 4 is a schematic diagram of an exemplary circuit breaker module on the input side of the voltage conversion circuit.

FIG. 5 is a diagram of an exemplary circuit breaker module on the output side of the voltage conversion circuit.

FIG. 6 is a schematic diagram of an exemplary circuit breaker module used on the output side of the voltage conversion circuit.

Fig. 7 is an exemplary diagram of a voltage conversion circuit in conjunction with a carrier communication module.

FIG. 8 is a schematic diagram of an exemplary circuit breaker module used on the input side of the voltage conversion circuit.

Fig. 9 is a schematic diagram of an exemplary voltage conversion circuit itself as a carrier communication module.

Detailed Description

The technical solutions of the present invention will be clearly and completely described below with reference to various embodiments, but the described embodiments are only used for describing and illustrating the present invention and not for describing all embodiments, and the solutions obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

Referring to fig. 1, a photovoltaic module array is a basis for converting light energy into electric energy of a photovoltaic power generation system, fig. 1 shows a photovoltaic module array installed with a plurality of basic cell strings 101, and each cell string 101 is formed by serially connecting a plurality of photovoltaic modules PV _1 and PV _2 … … PV _ N, each photovoltaic module or photovoltaic cell PV is configured with a power optimization circuit for performing maximum power tracking MPPT in the present application, for example, a photovoltaic voltage generated by a first photovoltaic module PV _1 is voltage-converted by a first power optimization circuit BS _1 to perform power optimization, a photovoltaic voltage generated by a second photovoltaic module PV _1 is voltage-converted by a second power optimization circuit BS _1, and so on until a photovoltaic voltage generated by an nth photovoltaic module PV-N is voltage-converted by an nth power optimization circuit BS _1The optimization circuit BS _ N performs voltage conversion to perform power optimization, N being a natural number. The voltage output by the power optimization circuit BS corresponding to each photovoltaic cell PV can represent the actual voltage provided by the photovoltaic cell PV on the photovoltaic cell string 101, assuming that the photovoltaic cell string 101 of any string is connected in series with the first-stage photovoltaic module PV _1, the second-stage photovoltaic module PV _1 … … to the nth-stage photovoltaic module PV _1, the first-stage power optimization circuit BS _1 is configured to perform maximum power tracking on the photovoltaic voltage source of the first-stage photovoltaic cell PV _1 to perform voltage conversion and output V _1₁Until the Nth-stage power optimization circuit BS _ N is used for carrying out maximum power tracking on the photovoltaic voltage source of the Nth-stage photovoltaic cell PV _ N for voltage conversion and outputting V_NIt can be known that the total string-level voltage on any string of photovoltaic strings 101 is equal to: voltage V output by first stage power optimization circuit BS _1₁Plus the voltage V output by the second stage power optimization circuit BS _2₂Then, the voltage … … output by the third stage power optimization circuit BS _3 is added until the voltage V output by the Nth stage power optimization circuit BS _ N is added_NThe operation result of the cascade voltage is equal to V₁+V₂+……V_N. The power optimization circuit BS can adopt a BOOST type BOOST, a BUCK type BUCK or a BOOST type BUCK-BOOST circuit. It should be emphasized that any solution for maximum power tracking of a photovoltaic cell disclosed and disclosed in the prior art is also applicable to the voltage converting circuit of the present application, and therefore, the present application does not give any further details on how the voltage converting circuit performs maximum power tracking. In fig. 1, the first-stage power optimization circuit BS _1, the second-stage power optimization circuit BS _2, through the nth-stage power optimization circuit BS _ N, and the like are connected in series through a transmission line LAN, and the cascade voltage superimposed on the transmission line LAN is transmitted to electric power equipment such as a combiner box or an inverter 170, and is combined and inverted and then is connected to an alternating current.

Referring to fig. 2, a known transmission line LAN connects in series the power optimization circuits BS corresponding to each photovoltaic cell PV so that the actual total voltage on the string 101 of photovoltaic cells is equal to V₁+V₂+……V_N. Also visible in fig. 2 is the photovoltaicThe cell PV is provided with a first-stage cell string ST₁And a second-stage battery string ST₁And the third-stage battery string ST₁And even greater numbers of battery strings. The efficiency of photovoltaic cells is mainly affected by two aspects: the first is the internal characteristics of the photovoltaic cell; the second is the ambient use environment of the photovoltaic cell, such as solar irradiance, load conditions, and temperature conditions. Under different ambient conditions, the photovoltaic cell can operate at different and unique maximum power points. Therefore, for a power generation system of a photovoltaic cell, the real-time optimal working state of the photovoltaic cell under any illumination condition should be sought so as to convert the light energy into electric energy to the maximum extent. For the photovoltaic module in fig. 1, when optimizing and tracking the maximum power point of a photovoltaic cell, the current technical means optimizes the output voltage and the output current of a certain photovoltaic module as a whole, calculates the output power and realizes tracking of the maximum power point, but not optimizes the string level of the cell. The biggest drawbacks of this optimization scheme are: only the output of the whole photovoltaic module is considered to be optimized, and the single cell string is not optimized, but the more practical situation is that: due to each battery string ST in any one photovoltaic module₁To ST₃The individual differences in photovoltaic characteristics, such as manufacturing differences, between each other, and the voltage levels of their respective outputs under the same lighting conditions are not necessarily identical, so that the maximum power point tracking of the entire photovoltaic module PV as a whole is not necessarily an ideal power output state. In the following of the present application, the present application will go to great extent to overcome the problems of the prior art and to introduce how to apply the battery string ST₁To ST₃Independent optimization of the battery string level is carried out, the existing PV level optimization is replaced, and light energy is converted into electric energy to the maximum extent.

Referring to fig. 3, the first battery string ST₁A first BOOST converter circuit BOOST1 is used to generate the desired voltage output. Referring to FIG. 3, the first input node NI1 of the first voltage conversion circuit BOOST1 in the power optimization circuit is connected to a corresponding one of the strings ST1 of PV modules PV _ K (K ≦ N) that uniquely corresponds to the BOOST1 circuit₁Of the first voltage conversion circuit BOOST1The second input node NI2 is connected to a battery string ST uniquely corresponding to the BOOST1 circuit₁The negative electrode of (1). And the first output node NO1 of the first voltage conversion circuit BOOST1 is connected to an output capacitor C corresponding to the photovoltaic module PV _ K only_OAnd the second output node NO2 of the first voltage conversion circuit BOOST1 is connected to the output capacitor C corresponding to the photovoltaic module PV _ K_OAnd a second end ND 2. In an alternative embodiment, an inductor L1 and a first switch S1 connected in series between a first input node NI1 and a first output node NO1 of the first voltage conversion circuit BOOST1 and a second input node NI2 thereof are coupled to a second output node NO2, wherein one end of the inductor L1 is coupled to the first input node NI1 and a first switch S1 is provided between the opposite end of the inductor L1 and the first output node NO1, an interconnection node N between the inductor L1 and the first switch S1_X1A second switch S2 is provided between the second input node NI2 or the second output node NO 2. Note that the first switch S1 in the voltage conversion circuit BOOST1 may also be replaced by a freewheeling diode. The basic principle of the MPPT of the boost type voltage conversion circuit is as follows: the first input NI1 and the second input NI2 of the BOOST1 circuit are from the first string ST₁The processor 200 for operating MPPT generates a first pulse width modulation signal PWM which is respectively coupled to the respective control terminals of the first switch S1 and the second switch S2, and during the MPPT switching period of the BOOST circuit BOOST1, the second switch S2 needs to be turned on: the modulation signal PWM drives the second switch S2 to turn on and turn off the freewheeling first switch S1, the current in the inductor L1 increases, the modulation signal PWM also drives the second switch S2 to turn off and turn on the freewheeling first switch S1, the current in the inductor L1 decreases and begins to discharge energy and become the capacitor C_OThe charging is performed, and the freewheeling switch S1 turned on at this time performs freewheeling, which is the basic principle of the BOOST type voltage conversion circuit. When the boost circuit performs the maximum power MPPT optimization operation, in other words, the first and second switches S1-S2 are periodically turned on alternately by the pulse width modulation signal PWM. It should be noted that Maximum Power Tracking in the industry is a mature technology, and the common Maximum Power Tracking in the prior art has a constant valueVoltage method, conductance increment method, disturbance observation method, etc., which are not described in detail herein.

Referring to fig. 3, the second battery string ST₂A second BOOST converter circuit BOOST2 is used to generate the desired voltage output. Referring to FIG. 3, the first input node NI1 of the second voltage conversion circuit BOOST2 in the power optimization circuit is connected to a corresponding one of the strings ST1 of PV modules PV _ K (K ≦ N) that uniquely corresponds to the BOOST2 circuit₂And the second input node NI2 of the second voltage conversion circuit BOOST2 is connected to a corresponding one of the battery strings ST uniquely corresponding to the BOOST2 circuit₂The negative electrode of (1). The first output node NO1 of the second voltage conversion circuit BOOST2 is connected to the output capacitor C uniquely corresponding to the photovoltaic module PV _ K_OAnd the second output node NO2 of the second voltage conversion circuit BOOST2 is connected to the output capacitor C uniquely corresponding to the photovoltaic module PV _ K_OAnd a second end ND 2. An inductor L1 and a first switch S1 connected in series between a first input node NI1 and a first output node NO1 of the second voltage conversion circuit BOOST2 and a second input node NI2 thereof are coupled to a second output node NO2, wherein one end of the inductor L1 is coupled to the first input node NI1 and a first switch S1 is provided between the opposite end of the inductor L1 and the first output node NO1, and an interconnection node N between the inductor L1 and the first switch S1_X2A second switch S2 is provided between the second input node NI2 or the second output node NO 2. Note that the first switch S1 in the voltage conversion circuit BOOST2 may also be replaced by a freewheeling diode. The basic principle of the second BOOST converter circuit is the same as the BOOST1 circuit: in the MPPT switching period of BOOST2, the second switch S2 needs to be turned on, the second modulation signal PWM generated by the processor 200 drives the second switch S2 to turn on and turn off the first switch S1, which results in the current of the inductor L1 increasing, the second modulation signal PWM also causes the second switch S2 to turn off and turn on the first switch S1, the current of the inductor L1 decreases and starts to release energy to the output capacitor C1_OCharging is performed, and at this time, the freewheeling first switch S1 is turned on to freewheel.

Referring to fig. 3, the third battery string ST₃Using a third BOOST BOOST transformThe circuit BOOST3 to produce the desired voltage output. Referring to FIG. 3, the first input node NI1 of the third voltage conversion circuit BOOST3 in the power optimization circuit is connected to a corresponding one of the strings ST1 of photovoltaic modules PV _ K (K ≦ N) that uniquely corresponds to the BOOST3 circuit₃And the second input node NI2 of the third voltage conversion circuit BOOST3 is connected to a corresponding one of the battery strings ST uniquely corresponding to the BOOST3 circuit₃The negative electrode of (1). The first output node NO1 of the third voltage conversion circuit BOOST3 is connected to the output capacitor C uniquely corresponding to the photovoltaic module PV _ K_OAnd the second output node NO2 of the third voltage conversion circuit BOOST3 is connected to the output capacitor C uniquely corresponding to the photovoltaic module PV _ K_OAnd a second end ND 2. An inductor L1 and a first switch S1 connected in series between a first input node NI1 and a first output node NO1 and a second input node NI2 thereof of a third voltage conversion circuit BOOST3 are coupled to a second output node NO2, wherein one end of the inductor L1 is coupled to the first input node NI1 and a first switch S1 is provided between the opposite end of the inductor L1 and the first output node NO1, and further an interconnection node N between the inductor L1 and the first switch S1 is provided_X3A second switch S2 is provided between the second input node NI2 or the second output node NO 2. Note that the first switch S1 in the third voltage conversion circuit BOOST3 may also be replaced by a freewheeling diode. The basic principle of the third BOOST converter circuit is the same as that of the BOOST1 circuit, the second switch S2 needs to be turned on during the MPPT switching period of the BOOST3 BOOST circuit, the third modulation signal PWM output by the processor 200 turns on the second switch S2 and turns off the first switch S1 to increase the current of the inductor L, and the modulation signal PWM also turns off and turns on the first switch S1 by the second switch S2, so that the current of the inductor L1 decreases and starts to discharge energy, thereby providing the capacitor C with a function of discharging energy_OCharging is performed, and at this time, the freewheeling first switch S1 is turned on to freewheel.

Referring to fig. 2 in conjunction with fig. 3, the respective power optimization circuits BS of each photovoltaic cell PV are connected in series on the transmission line LAN such that the actual total voltage across the string 101 of photovoltaic cells is equal to V₁+V₂+…V_N. Let us take an arbitrary photovoltaic cell PV as an example, whichMiddle first-stage battery string ST₁And a second-stage battery string ST₁And a third-stage battery string ST₁The voltage generated by each individual due to its own battery characteristics may be too low, and for example, the voltage generated by each individual battery String may also be too low under the condition that the intensity of light at that time is not very strong, and according to the disclosure of the present application, the output capacitor C corresponding to a certain photovoltaic cell PV can be greatly raised by using the BOOST1-BOOST3_OThe total voltage on the battery string 101 is equal to V₁+…V_NThe requirements are still met.

Referring to fig. 4, in an alternative embodiment, the first input node NI1 of the first voltage conversion circuit BOOST1 and the battery string ST may be connected₁Or alternatively, a disconnection module BRE may be provided between the second input node NI2 of the first voltage conversion circuit BOOST1 and the battery string ST₁A breaking module BRE is arranged between the negative poles. Or between the first output node NO1 of the first voltage conversion circuit BOOST1 and the output capacitor C_OA circuit breaking module BRE is arranged between the first terminal ND1, or between the second output node NO2 of the first voltage conversion circuit BOOST1 and the output capacitor C_OAnd a break module BRE is disposed between the second ends ND 2. The significance of the disconnection module is that the boost type circuit needs to be controlled to stop operating/sleeping under certain conditions, for example, some individual cells in the photovoltaic module PV _ K have too high temperature and even cause unexpected faults such as fire, and for example, if the module needs to be repaired manually or the whole or part of the power system needs to be inspected, the personal safety of inspection personnel can be prevented from being endangered by high voltage. The breaking module BRE uses, for example, relays or the like, which can be directly activated by the processor 200 to execute the command of turning off/on.

Referring to fig. 4, according to the same principle, the battery string ST uniquely corresponding to the BOOST2 and the first input node NI1 of the voltage conversion circuit BOOST2 can be also provided₂Between the positive pole of the battery string ST and a disconnection module BRE or between the second input node NI2 of the BOOST2 and the battery string ST₂And a break module BRE is arranged between the negative poles. Or at the first output node NO1 of BOOST2 and an output capacitance uniquely corresponding to PV _ KC_OOr a second output node NO2 of the BOOST2 and an output capacitor C uniquely corresponding to PV _ K_OAnd a break module BRE is disposed between the second ends ND 2. It is also possible to provide the first input node NI1 of the voltage conversion circuit BOOST3 and the battery string ST uniquely corresponding to the BOOST circuit BOOST3₃Between the positive pole of the battery string ST and a disconnection module BRE or between the second input node NI2 of the BOOST3 and the battery string ST₃A break module BRE is arranged between the negative poles; or at the first output node NO1 of BOOST3 and the output capacitor C corresponding to PV _ K_OOr a second output node NO2 of the BOOST3 and an output capacitor C uniquely corresponding to PV _ K_OAnd a break module BRE is disposed between the second ends ND 2. The shutdown module BRE may be controlled by the processor 200 to execute off/on commands to control the operating states of the voltage conversion circuits BOOST2-BOOST 3.

Referring to fig. 5, a preset/designated voltage conversion circuit BOOST2 is defined in the multi-stage voltage conversion circuits BOOST1-BOOST3 corresponding to a certain photovoltaic module PV _ K, and actually, either BOOST1 or BOOST3 can be used as the designated voltage conversion circuit, but we take the designated BOOST2 as an example to illustrate the spirit of the invention. At the second output node NO2 of the predetermined voltage conversion circuit BOOST2 and the output capacitor C corresponding to PV _ K_OAnd a second end of the same module, a breaking module BRE is arranged between the second ends, which is slightly different from the case of using a plurality of breaking modules RED in fig. 4, and the embodiment of fig. 5 can realize the same breaking functions of turning off/on and the like as those of fig. 5 only by using a single breaking module BRE. In the multi-stage voltage conversion circuits BOOST1-BOOST3 corresponding to the photovoltaic module PV _ K, in addition to the preset voltage conversion circuit BOOST2, the second output node NO2 of each of the other remaining voltage conversion circuits BOOST1, BOOST3 is coupled to the second output node NO2 of the preset voltage conversion circuit BOOST2, fig. 5 shows that the second output node NO2 of the voltage conversion circuit BOOST1 is directly coupled to the second output node NO2 of the preset voltage conversion circuit BOOST2, and the second output node NO2 of the voltage conversion circuit BOOST3 is also directly coupled to the second output node NO2 of the preset voltage conversion circuit BOOST2,so that only the second output node NO2 and the output capacitor C of the second voltage conversion circuit BOOST2 are required_OThe shutdown module BRE disposed between the second terminal ND2 is turned off, then the first and third voltage conversion circuits BOOST1-3 are also turned off synchronously. The single shutdown module BRE of fig. 5 is also under the control of the processor 200 and can execute an off/on instruction to synchronously control the operating states of the first through third voltage conversion circuits BOOST1-BOOST 3.

Referring to fig. 6, a preset/designated voltage conversion circuit BOOST2 is defined in the multi-stage voltage conversion circuits BOOST1-BOOST3 corresponding to a certain photovoltaic module PV _ K, and an output capacitor C uniquely corresponding to PV _ K is defined at the first output node NI1 of the preset voltage conversion circuit BOOST2_OThe breaking module BRE is disposed between the first terminals ND1, and in the multi-stage voltage conversion circuits BOOST1-BOOST3 corresponding to the photovoltaic modules PV _ K, except for the preset voltage conversion circuit BOOST2, the first output node NO1 of each of the remaining other voltage conversion circuits BOOST1 and BOOST3 is directly coupled to the first output node NO1 of the preset voltage conversion circuit BOOST 2. FIG. 6 shows that the first output node NO1 of the first voltage conversion circuit BOOST1 is coupled to the first output node NO1 of the predetermined second voltage conversion circuit BOOST2, and the first output node NO1 of the third voltage conversion circuit BOOST3 is also coupled directly to the first output node NO1 of the predetermined second voltage conversion circuit BOOST2, so that only the first output node NO1 of the second voltage conversion circuit BOOST2 and the output capacitor C_OThe circuit breaking module BRE arranged between the first terminals ND1 is off, which means that the first and third voltage conversion circuits BOOST1, BOOST3 are also synchronously off. The single trip module BRE of fig. 6 is also under the control of the processor 200 and the processor may issue commands instructing the BRE to turn off and/or on to control the operating states of the first through third voltage conversion circuits BOOST1-BOOST3 synchronously.

The photovoltaic module or photovoltaic cell PV is one of the core components of the photovoltaic power generation system, the solar panel is divided into monocrystalline silicon solar cell, polycrystalline silicon solar cell, amorphous silicon solar cell and the like in the direction of the current mainstream technology, and since the service life required by the silicon cell in the field is generally as long as twenty years, the monitoring of the long-term property and the durability of the panel is essential. Many factors cause the reduction of the power generation efficiency of the photovoltaic module, and factors such as manufacturing differences, installation differences or shadow occlusion or maximum power tracking adaptation among the photovoltaic modules themselves cause the efficiency to be low. Taking a typical shadow shielding as an example, if a part of photovoltaic modules is shielded by clouds or buildings or tree shadows or dirt and the like, the part of the photovoltaic modules can be changed into load by a power supply and does not generate electric energy any more, because the local temperature of the photovoltaic modules at places with serious hot spot effect may be higher, and some of the photovoltaic modules even exceed 150 ℃, the local area of the photovoltaic modules is burnt or forms dark spots, welding spots are melted, packaging materials are aged, glass is cracked and corroded, and the like, permanent damage is caused to the long-term safety and reliability of the photovoltaic modules, and great hidden danger is caused. The problems to be solved by photovoltaic power stations/systems are as follows: the working state of each installed photovoltaic cell panel can be observed in real time, the early warning can be carried out on abnormal conditions such as over-temperature, over-voltage, over-current and output end short circuit of the battery, and the emergency warning device is very meaningful for taking active safety shutdown or other emergency measures for the abnormal battery.

Referring to fig. 7, in order to achieve these predetermined objectives, the photovoltaic module monitoring system integrated with a communication function, which is described later in the present application, may reflect all operating parameters of the photovoltaic cells onto the power line by using power carriers, which provides a suitable solution for the photovoltaic power station to perform fault alarm, fault fast positioning, etc. on the cells, and is suitable for grid-connected or off-grid photovoltaic power generation systems of different scales. The carrier sending module 250 is used in cooperation with the processor 200, the processor 200 collects a series of specified operating parameters such as voltage, current, power, temperature and the like of the photovoltaic cell PV by using a collection module not shown in the figure, it is noted that the collection module for collecting the operating parameters belongs to the prior art, and the scheme of any parameter of the cell capable of being collected is compatible with the present application, so that the present collection module is not separately explained in the present application. The processor 200 may also receive information such as data or instructions sent by other electronic devices to the transmission line LAN, and respond and reply. In the embodiment shown in fig. 7, the processor 200 needs to be configured with a carrier transmission module 250 coupled to the slave power line LAN for transmitting data from the battery side to some other electronic device that can decode the carrier signal, and the carrier transmission module is used for coupling the carrier signal generated by the carrier transmission module to the transmission line LAN. As one of the aspects of sensing and decoding the carrier signal, the decoder generally has a sensor module, a band pass filter module, a processing unit, etc., wherein a power line passes through the sensor module (such as a rogowski air coil sensor, etc.) to detect the carrier signal on the transmission line by the sensor module, and in order to more accurately capture real carrier data and shield noise, the band pass filter module needs to filter the carrier signal sensed by the sensor module, mainly filter out noise waves not within a specified frequency range, and only the carrier within the specified frequency range can represent an expected real carrier signal, and the processing unit receives the real carrier signal and decodes the carrier data thereof.

Referring to fig. 7, the carrier transmission module 250 includes a shunt capacitor C connected in parallel_BCAnd a second resistor R₂And a switching device S_BCA first resistor R₁On the connection relationship: bypass capacitor C_BCAnd a second resistor R₂First connected in parallel and then connected with the switching device S_BCA first resistor R₁Is connected in series to an output capacitor C_OBetween the first terminal ND1 and the second terminal ND2, note the parallel configuration (C)_BC-R₂) A first resistor R₁Switching device S_BCThe serial position relationship of the three parts between the first end ND1 and the second end ND2 can be changed arbitrarily. A plurality of photovoltaic modules PV _1 … … PV _ N are connected in series to form a battery string 101, and the output capacitance C of each photovoltaic module PV _1 … … PV _ N in each battery string 101_OConnected in series with each other, in series relation: output capacitor C uniquely corresponding to any current-stage photovoltaic module PV _ K_OIs connected to the output capacitor C corresponding to the previous photovoltaic assembly PV _ K-1_OSecond terminal ND2, output capacitor C corresponding to the photovoltaic module PV _ K of the current stage_OIs connected to the next stage of photovoltaic module PV _ K +1 onlyA corresponding output capacitor C_OFirst terminal ND1, output capacitance C of each of photovoltaic modules PV _1 … … PV _ N_OWhereby they are connected in series with each other through the transmission line LAN. In the present application, it can be considered that the multi-level voltage conversion circuits BOOST1-BOOST3 corresponding to the photovoltaic module PV _ K are commonly configured with a first terminal ND1 and a second terminal ND2 for outputting a voltage, where the output voltage is a voltage commonly output by the multi-level voltage conversion circuits BOOST1-BOOST3, and an output capacitor C can be further connected between the first terminal ND1 and the second terminal ND2_O. The first terminal ND1 and the second terminal ND2 may also be referred to as a first voltage output terminal and a second voltage output terminal, respectively.

Referring to fig. 7, the output capacitor C uniquely corresponds to any one photovoltaic module PV _ K_OIs provided with an output capacitor C uniquely corresponding to PV _ K between the first end ND1 and the second end ND2_OAnd a parallel carrier transmitting module 250. It can also be said that: a carrier transmitting module 250 is connected between the first terminal ND1 and the second terminal ND2 of the multi-stage voltage conversion circuit BOOST1-BOOST3 configuration corresponding to the photovoltaic module PV _ K. And is also at the output capacitor C_OIs provided with an output capacitor C between the first end ND1 and the second end ND2_OSeries control switch S_OC is connected in series between a first end ND1 and a second end ND2 for output voltage which are equivalent to the common configuration of BOOST1-BOOST3_OAnd S_O. Branch of the observation carrier sending module 250: comprises a first resistor R₁Bypass capacitor S_BCAnd a switching element S_OA shunt capacitor S connected in parallel with the branch_BCSecond resistor R at two ends₁. At the stage when the carrier transmission module 250 broadcasts/transmits the carrier signal onto the transmission line LAN: processor 200 controls switch S_OWhen switching between on and off, the hopping current flowing through the branch of the carrier transmitter module 250 is injected onto the transmission line LAN as a carrier signal carrying data, when the switching element S is switched on_OIn the event of a switching-on transient, a current flow occurs in the branch, i.e. the current jumps in the branch, but the switching element S is still in the current flow state_OTransient state of turn-off the current of the branch is instantaneously cut off-its state of current jumpsIs that there is no current in the branch. According to this scheme of perturbation on the transmission line LAN, the signal S for driving S is generated in the branch and output from the processor 200_BCThe drive signal of (a) is a current that jumps almost at the frequency.

See fig. 7, for example, bypass capacitor C_BCAnd a second resistor R₂After their respective terminals are interconnected, their interconnected terminals are connected to an output capacitor C_OIs connected with a first resistor R between the first ends ND1₁Bypass capacitor C_BCAnd a second resistor R₂The opposite ends of each are interconnected and then connected to a switching device S_OOn one terminal of the switching device S_OIs directly connected to the output capacitor C_OAnd a second end ND 2. In the carrier circuit, the switch S may be held first_OIn the off state, if the processor 200 tries to establish communication interaction with an external electronic device through a carrier wave, the driving signal sent by the processor 200 is rapidly transited from the first logic state (e.g., low level) to the second logic state (e.g., high level) and then returns to the first logic state, so that the switch S turned on under driving_OIs turned on and off, the off-on-off process may be repeated multiple times. Consider that in the communication phase: control switch S_OHas a rising or falling edge moment of a nearly transient jump, switches S are closed_OResulting in harmonics or carrier currents flowing through the carrier branch, which are injected onto the transmission line LAN. Various carrier detection means (such as an air-core coil sensor or a high-frequency transformer, a band-pass filter, a de-encoder) can be utilized to extract the carrier signal sent by the carrier sending module from the current information flowing on the power transmission line for demodulation. Although not shown, the processor 200 may monitor data parameters such as output voltage and output current of the photovoltaic cells PV, power and temperature by using various detection means, and the data may be broadcasted to the transmission line LAN by the processor in a manner of controlling the carrier transmission module 250 to transmit the carrier, such as a dotted propagation path.

Referring to fig. 7, a plurality of photovoltaic modules PV _1 … … PV _ N are connected in series to form a battery string 101, and light is emitted in each battery string 101Respective output capacitances C of the voltage assemblies PV _1 … … PV _ N_OAre connected in series with each other. Note that among the plurality of series connected photovoltaic modules: the carrier waves emitted by any current photovoltaic module need to be propagated between the first terminal ND1 and the second terminal ND2 arranged in the multi-stage voltage conversion circuits BOOST1-BOOST3 of other photovoltaic modules, so that a proper communication path should be established between the first terminal ND1 and the second terminal ND2 arranged in the multi-stage voltage conversion circuits BOOST1-BOOST3 of other photovoltaic modules. For example: in fig. 7, the PV modules PV _1 … … PV _ N are connected in series, and the example of the PV modules PV _ K and PV module PV _ K-1 is taken to illustrate the communication mechanism. The photovoltaic module PV _ K of the current K-th level is power-optimized by using the power optimization circuit BS _ K, while the photovoltaic module PV _ K of the previous level, that is, the K-1-th level, is power-optimized by using the power optimization circuit BS _ K-1, and both the power optimization circuits BS _ K and BS _ K-1 may include the circuits from BOOST1 to BOOST3 described above, although the optimization circuits may also adopt other power optimization schemes in the prior art. The multistage voltage conversion circuit (BS _ K) uniquely corresponding to the photovoltaic module PV _ K is provided with a first terminal ND1 and a second terminal ND2, and C is connected in series between the first terminal ND1 and the second terminal ND2 of the multistage voltage conversion circuit (BS _ K) corresponding to the module PV _ K_OAnd S_O. Meanwhile, the multi-stage voltage conversion circuit (BS _ K-1) uniquely corresponding to the photovoltaic module PV _ K-1 is provided with a first terminal ND1 and a second terminal ND2, and C is connected in series between the first terminal ND1 and the second terminal ND2 of the multi-stage voltage conversion circuit (BS _ K-1) corresponding to the photovoltaic module PV _ K-1_OAnd S_O. In order to easily distinguish a preset/designated photovoltaic module PV _ K from the series-connected photovoltaic modules PV _1 … … PV _ N, at the stage when a carrier transmitting module 250 corresponding to the preset/designated photovoltaic module PV _ K transmits a carrier signal to the transmission line LAN, the output capacitor C corresponding to the designated photovoltaic module PV _ K_OControl switches S connected in series_OIn the off state, the processor 200 associated with the photovoltaic module PV _ K drives the switch S_OThe control switch S corresponding to each other photovoltaic module except the designated photovoltaic module PV _ K in the battery string 101 is turned off_OIn the on state to form carrier signalsPropagation path of the signal, i.e. output capacitance C of other photovoltaic modules_OShould be in an on state to allow the carrier to smoothly go from the C between the first end ND1 and the second end ND2_O/S_OAnd broadcasting the path. How the carrier transmitted by the carrier transmitting module 250 of the PV module PV _ K configuration propagates between the first terminal ND1 and the second terminal ND2 provided in the multi-stage voltage conversion circuit respectively corresponding to other respective PV modules is explained in detail, for example, by using any of the PV modules PV _ K-1 of the previous stage as a representative of the respective other PV modules in the battery string 101 except the designated PV module PV _ K. First analyzing each capacitance C_OHow to connect in series: the first end ND1 arranged on the multistage voltage conversion circuit (BS _ K) corresponding to the photovoltaic module PV _ K of the previous stage is directly connected to the second end ND2 arranged on the multistage voltage conversion circuit (BS _ K-1) corresponding to the photovoltaic module PV _ K-1 of the previous stage through the transmission line LAN, and similarly, the second end ND2 arranged on the multistage voltage conversion circuit (BS _ K) corresponding to the photovoltaic module PV _ K of the previous stage is also directly connected to the first end ND1 arranged on the multistage voltage conversion circuit (BS _ K +1) corresponding to the photovoltaic module PV _ K +1 of the next stage through the transmission line LAN. Based on the above topology, the carrier transmitted by the carrier transmitting module 250 of the PV module PV _ K configuration is coupled to the first terminal ND1 and the second terminal ND2 provided in the voltage converting circuit (BS _ K), and is also coupled to the transmission line LAN, and the carrier needs to propagate between the first terminal ND1 and the second terminal ND2 provided in the multi-stage voltage converting circuit (BS _ K-1) corresponding to the PV module PV _ K-1, so the processor 200 associated with the PV module PV _ K-1 must configure the switch S associated with the PV module PV _ K-1_OA switch S provided between a first terminal ND1 and a second terminal ND2 provided in the multistage voltage conversion circuit (BS _ K-1) is turned on_OAfter the carrier wave is switched on, the carrier wave transmitted by the carrier wave transmitting module 250 configured to the photovoltaic module PV _ K can smoothly propagate on a path between the first terminal ND1 and the second terminal ND2 of the multi-stage voltage converting circuit (BS _ K-1), otherwise, the carrier wave transmitted by the current stage of photovoltaic module PV _ K is cut off between the first terminal ND1 and the second terminal ND2 of the other photovoltaic modules PV _ K-1. FIG. 7 is combined with FIGS. 3-6. in other alternative embodiments, in addition to multiple stages of powerThe voltage conversion circuit (BS _ K-1) is provided with a switch S between a first terminal ND1 and a second terminal ND2_OIn addition to being turned on, the carrier path may be constructed by simultaneously turning on the first switch S1 and the second switch S2 of any one BOOST in the multistage voltage conversion circuit (BS _ K-1), specifically, for example, even if the multistage voltage conversion circuit (BS _ K-1) is provided with the switch S between the first terminal ND1 and the second terminal ND2_OAnd is turned off, but the first switch S1 and the second switch S2 of any one BOOST1 or BOOST2 or BOOST3 of the multi-stage voltage conversion circuit (BS _ K-1) are simultaneously turned on, the carrier signal can freely propagate between the first end ND1 and the second end ND2 provided in the multi-stage voltage conversion circuit (BS _ K-1) through the first switch S1 and the second switch S2 of any one BOOST of the multi-stage voltage conversion circuit (BS _ K-1). That is, in the stage of sending carrier waves by the currently designated component, if other photovoltaic components select to switch S in the communication stage_OAnd when the photovoltaic modules are switched off, the rest of the photovoltaic modules in the battery string can be switched on to switch on the switches S1-S2 of any one of the BOOSTs so as to build a propagation path of the carrier signal.

Referring to fig. 8, slightly different from the embodiments of fig. 3 to 6, a preset voltage conversion circuit BOOST2 is defined in the multi-stage voltage conversion circuits BOOST1-BOOST3 corresponding to any one of the photovoltaic modules PV _ K, wherein a disconnection module BRE is provided between the second input node NI2 of the preset voltage conversion circuit BOOST2 and the negative pole of a battery string ST _2 uniquely corresponding to the preset voltage conversion circuit BOOST2, and in the multi-stage voltage conversion circuit BOOST1-BOOST3 corresponding to the any one photovoltaic module PV _ K, in addition to the preset voltage conversion circuit BOOST2, the second output node NI2 of each of the other voltage conversion circuits, i.e., BOOST1 and BOOST3, in the remaining multi-stage voltage conversion circuits BOOST1-BOOST3 is also connected to the negative electrode of the battery string uniquely corresponding to each of the other voltage conversion circuits BOOST1 and BOOST3 through the shutdown module BRE. Specifically, for example, the circuit breaking module BRE is arranged between the second input node NI2 of the second voltage conversion circuit BOOST2 and the negative electrode of the battery string ST _2 uniquely corresponding to the BOOST2, but the second input node NI2 of the first voltage conversion circuit BOOST1 passes through the circuit breaking module BREThe other technical features of the multi-stage voltage converting circuit of fig. 8 are substantially the same as the embodiment of fig. 3, except that the second input node NI2 of the third voltage converting circuit BOOST3 is connected to the cathode of the battery string ST _1 uniquely corresponding to the BOOST1 after the break module BRE, and then to the cathode of the battery string ST _3 uniquely corresponding to the BOOST 3. In the present application, another identification of the first battery string ST _1 corresponding to the BOOST1 circuit is ST₁Another identification of the second battery string ST _2 corresponding to the BOOST2 circuit is ST₂Another identification of the third battery string ST _3 corresponding to the BOOST3 circuit is ST₃. Wherein the battery string ST _1 is optimized by the BOOST1 circuit, the battery string ST _2 is optimized by the BOOST2 circuit, and the battery string ST _3 is optimized by the BOOST3 circuit. The advantage of fig. 8 over fig. 5-6 is: in fig. 8, even after the shutdown module is turned off, the first switch S1 and the second switch S2 of any one of the BOOST1-3 may be controlled to be turned on to establish a path of voltage/current or carrier between the first terminal ND1 and the second terminal ND 2; however, after the disconnection module in fig. 5-6 is turned off, the voltage/current and carrier paths cannot be established between the first terminal ND1 and the second terminal ND2 of the voltage conversion circuit BOOST1-BOOST corresponding to the photovoltaic module PV _ K.

Referring to fig. 9, slightly different from the embodiment of fig. 7, the transmission of carriers can also be implemented. And a plurality of photovoltaic modules PV _1 … … PV _ N are connected in series to form a battery string 101, and the output capacitance C of each of the plurality of photovoltaic modules PV _1 … … PV _ N in each battery string 101_OOutput capacitors C connected in series and corresponding to the photovoltaic modules_OAre connected in series with each other through a transmission line LAN. In the embodiment of fig. 9, the multi-stage voltage conversion circuit of the PV module PV _ K configuration (i.e. each BOOST1-BOOST3 circuit of the BS _ K) is provided with a first terminal ND1 and a second terminal ND2, and further, a switch S is connected in series between the first terminal ND1 and the second terminal ND2 of the multi-stage voltage conversion circuit or optimization circuit BS _ K of the PV _ K configuration_OAnd a capacitor C_O. Note that switch S in the embodiment of FIG. 9_OThe manner used to generate the carrier wave is different from that of fig. 7. Multiple stages corresponding to each photovoltaic module PV _ KThe voltage conversion circuit BOOST1-BOOST3 has/corresponds to an output capacitor C_OAnd an output capacitor C is arranged between the first end ND1 and the second end ND2_OSeries control switch S_O(ii) a The control switch S configured by the multi-stage voltage conversion circuit BOOST1-BOOST3 corresponding to any one photovoltaic module PV _ K_OWhen the photovoltaic module PV _ K is turned on, the multi-stage voltage conversion circuits BOOST1-BOOST3 corresponding to the any one of the photovoltaic modules PV _ K are in the first operating mode for converting the received voltage to output, that is, the first BOOST1 is in the operating mode for converting the photovoltaic voltage of the first ST _1 to output, the second BOOST2 is in the operating mode for converting the photovoltaic voltage of the second ST _2 to output, and the third BOOST3 is in the operating mode for converting the photovoltaic voltage of the third ST _3 to output. Note that the voltage conversion circuits BOOST1-BOOST3 in the first mode of operation refers to the process of power optimization performed by the PWM driven voltage conversion circuits output by processor 200. In contrast, if any one of the photovoltaic modules PV _ K corresponds to the multi-level voltage conversion circuit BOOST1-BOOST3, the control switch S is configured_OWhen the photovoltaic module PV _ K is turned off, any specific circuit (for example, the BOOST1, the BOOST2, or the BOOST3) in the multi-stage voltage conversion circuits BOOST1-BOOST3 corresponding to the any photovoltaic module PV _ K is in a second operation mode for coupling the excitation pulse Signal, which jumps between high and low levels, to the transmission line LAN as a carrier Signal, and the excitation pulse Signal is mainly coupled to the transmission line LAN from the first end ND1 and the second end ND2 carried by the multi-stage voltage conversion circuits BOOST1-BOOST3 corresponding to the photovoltaic module PV _ K. Wherein the excitation pulse Signal originates from: the PWM Signal PWM for driving the specific circuit among the multi-stage voltage conversion circuits BOOST1-BOOST3 forces the voltage output from the specific circuit (from the first and second output nodes NO1-NO2) to change in steps with the frequency of the PWM Signal PWM, and the step voltage output from the first and second output nodes NO1-NO2 is regarded as the excitation pulse Signal.

Referring to fig. 9, taking the first to third voltage conversion circuits BOOST1-3 of the multi-stage voltage conversion circuits BOOST1-BOOST3 corresponding to the photovoltaic module PV _ K as an example, the output power of each of the BOOST1-3The voltages are respectively output to an output capacitor C_OAt this time, the control switch S set by the voltage conversion circuit BOOST1-3_OAnd an output capacitor C_OIs connected in series between a first terminal ND1 and a second terminal ND2 of the voltage conversion circuit BOOST 1-3. In the normal phase, the control switch S of the voltage conversion circuit BOOST1-3_OWhen the photovoltaic power supply is switched on, the BOOST1-3 carries out MPPT on the photovoltaic voltage generated by each receiving photovoltaic cell for voltage conversion and output to the output capacitor C_OIn this stage, the voltage converting circuits BOOST1-3 are shown as a normal voltage converter and can output a more normal and stable voltage, and although the voltage output by the voltage converting circuits BOOST1, BOOST2 or BOOST3 has ripples, the output voltage is substantially stabilized at the upper limit V_UPPERAnd a lower limit value V_LOWERWithin a range in which the maximum ripple amplitude of the output voltage does not exceed V_UPPERMinimum ripple amplitude not less than V_LOWER. That is, the multi-stage voltage conversion circuit BOOST1-BOOST3 corresponding to the any one of the photovoltaic modules PV _ K is in the first operation mode for converting the voltage received from the battery string to be output (here, boosted voltage, and reduced voltage if the BUCK circuit is used).

Referring to FIG. 9, once the processor 200 sets the control switch S of the voltage conversion circuit BOOST1-3 corresponding to PV _ K_OOff, the voltage conversion circuit BOOST1 or BOOST2 or BOOST3 will output a stimulus pulse instead of a steady voltage value. The reason is that: at this time, the PWM signal PWM originally driving the voltage conversion circuit BOOST1-3 forces the voltage output by the BOOST1 or BOOST2 or BOOST3 to have a step change with the frequency of the PWM signal. Taking BOOST1 as an example, the basic reason is that the output voltage of BOOST1 is originally output in the output capacitor C_OUpper, but output capacitance C_OBut is forced to disconnect from the first output node NO1 and the second output node NO2 of the BOOST1, resulting in a step change of the voltage value between the first output node NO1 and the second output node NO2 with the same frequency as the frequency of the pwm signal that would otherwise be used to modulate the first voltage conversion circuit BOOST1, the first output node NO1 and the second output node NO1 of the BOOST1The step voltage output between NO2 is considered as an excitation pulse Signal. According to the scheme, the total output voltage of the BOOST1 is specially induced to jump between high and low levels, and the forward amplitude of an excitation pulse Signal is larger than an upper limit value V_UPPERAnd its negative amplitude is lower than lower limit value V_LOWERThe excitation pulse is easily captured from a stable, steady voltage from the transmission line LAN. The voltage conversion circuit BOOST1 couples the excitation pulse (which has substantially the same frequency as the pulse modulation signal PWM driving the voltage conversion circuit BOOST 1) that jumps between high and low levels to each capacitor C connected in series_OAs a carrier signal on the transmission line LAN, thus turning off the switch S_OThe resulting excitation pulse Signal is considered to be a carrier Signal. Alternatively, but not necessarily, BOOST1-BOOST3 output the stimulus pulses synchronously with the greater amplitude of the stimulus sources on the LAN.

Referring to fig. 9, the communication method for the processor 200 to transmit data is implemented as follows: during the time period T when the processor 200 transmits the binary data 0 (or 1) using the carrier signal, the processor 200 controls the band switch S_OBS _ K of_OIs always turned on in any one period of the time period T, the BOOST1-3 is brought into the first operation mode at normal voltage transition in the period without outputting any form of stimulus pulse, so that the symbol outputted between the first terminal ND1 and the second terminal ND2 of the BOOST1-3 is 0 (or 1). On the contrary, in the period T in which the processor 200 transmits binary data 1 (or 0) using the carrier signal, the processor 200 controls the signal with the switch S_OBS _ K of_OAnd the output voltage is switched off at least once in any period of the time period T, so that the BOOST1-3 enters a second working mode of abnormal voltage conversion at least once in the period and outputs no less than one cluster of the excitation pulse Signal, and the output code element between the first end ND1 and the second end ND2 of the BOOST1-3 is 1 (or 0). In the preferred embodiment, the first start byte/start bit of the first cycle of the time period T is preferably represented by the presence of at least one excitation pulse, since the excitation pulse Signal is clearly distinguishable from the plateau voltage output by BOOST1-3, and the start byte is maintained in the positive mode of operation by the presence of an abnormal voltage transition in the second mode of operation rather than being maintained at all timesThe normal first voltage operation mode can easily identify that the communication procedure for transmitting data is started. The carrier wave propagates on the path shown by the dashed line.

Referring to fig. 9, it is obvious that the BOOST1-3 circuit corresponding to PV _ K is not a normal voltage converter in the phase of sending the carrier signal, and cannot output a more normal stable voltage value, and at this time, the pulse width modulation signal of the driving voltage conversion circuit BOOST1-3 is originally used for performing MPPT calculation, but because the control switch S controls the switch S_OBeing switched off results in the pulse width modulated signal PWM being the source of the excitation pulse generation. Compared with the embodiment of fig. 7, in the embodiment of fig. 9, the voltage conversion circuit BOOST1-3 itself directly doubles as a carrier transmitting circuit, and there is no need to provide an additional carrier transmitting module 250 as in fig. 7.

While the present invention has been described with reference to the preferred embodiments and illustrative embodiments, it is to be understood that the invention as described is not limited to the disclosed embodiments. Various alterations and modifications will no doubt become apparent to those skilled in the art after having read the above description. Therefore, the appended claims should be construed to cover all such variations and modifications as fall within the true spirit and scope of the invention. Any and all equivalent ranges and contents within the scope of the claims should be considered to be within the intent and scope of the present invention.

Claims

1. A photovoltaic module power optimization circuit, any one photovoltaic module all has multistage battery cluster, its characterized in that:

each photovoltaic module is provided with a multi-stage voltage conversion circuit with the number consistent with that of the battery strings;

wherein in the multistage voltage conversion circuit corresponding to any one photovoltaic module: each stage of voltage conversion circuit is used for independently performing maximum power tracking on a corresponding battery string in any one photovoltaic module;

the multi-stage voltage conversion circuits corresponding to any one photovoltaic module are connected in parallel, so that the voltages output by the multi-stage voltage conversion circuits are output to an output capacitor corresponding to the any one photovoltaic module together;

in the multistage voltage conversion circuit corresponding to any one photovoltaic module:

the first input node and the second input node of each voltage conversion circuit are correspondingly and respectively connected to the positive electrode and the negative electrode of a corresponding battery string in any one photovoltaic assembly; and

the first output node and the second output node of each voltage conversion circuit are correspondingly connected to the first end and the second end of an output capacitor corresponding to the any one photovoltaic module respectively;

a plurality of photovoltaic modules are connected in series to form a battery pack string, and output capacitors corresponding to the photovoltaic modules in each battery pack string are connected in series through transmission lines;

a control switch connected in series with an output capacitor is arranged between a first end and a second end of the output capacitor of the multi-level voltage conversion circuit corresponding to each photovoltaic module;

when the control switch configured by the multi-level voltage conversion circuit corresponding to any one photovoltaic module is switched on, the multi-level voltage conversion circuit corresponding to the any one photovoltaic module is in a first working mode of converting and outputting the received voltage;

when the control switch configured by the multi-level voltage conversion circuit corresponding to any one photovoltaic module is turned off, any one appointed circuit in the multi-level voltage conversion circuit corresponding to any one photovoltaic module is in a second working mode of coupling excitation pulses jumping between high and low levels to the transmission line as a carrier signal;

wherein the excitation pulse originates from: the pulse width modulation signal used for driving the specified circuit forces the voltage output by the specified circuit to have step change along with the frequency of the pulse width modulation signal, and the output step voltage is regarded as an excitation pulse.

2. The photovoltaic module power optimization circuit of claim 1, wherein the total voltage of each string of cells is equal to the sum of the voltages across the respective output capacitors of the photovoltaic modules connected in series.

3. The photovoltaic module power optimization circuit of claim 1, wherein the voltage conversion circuits are boost type voltage conversion circuits, each voltage conversion circuit having an inductor and a first switch connected in series between a first input node and a first output node and a second input node coupled to a second output node, wherein one end of the inductor is coupled to the first input node and a first switch is disposed between an opposite end and the first output node, and a second switch is disposed between an interconnection node between the inductor and the first switch and the second input node or the second output node.

4. The photovoltaic module power optimization circuit of claim 1, wherein a disconnection module is provided between the first input node of each voltage conversion circuit and the positive pole of the battery string or between the second input node thereof and the negative pole of the battery string; or

A circuit breaking module is arranged between the first output node of each voltage conversion circuit and the first end of the output capacitor or between the second output node of each voltage conversion circuit and the second end of the output capacitor.

5. The photovoltaic module power optimization circuit according to claim 1, wherein a preset voltage conversion circuit is defined in the multi-stage voltage conversion circuit corresponding to any one photovoltaic module; wherein

A circuit breaking module is arranged between a first output node of the preset voltage conversion circuit and a first end of the output capacitor; in the multi-stage voltage conversion circuit corresponding to any one photovoltaic module, the first output nodes of other voltage conversion circuits except the preset voltage conversion circuit are coupled to the first output node of the preset voltage conversion circuit; or

A circuit breaking module is arranged between a second output node of the preset voltage conversion circuit and a second end of the output capacitor; in the multi-stage voltage conversion circuit corresponding to any one photovoltaic module, the second output nodes of the other voltage conversion circuits except the preset voltage conversion circuit are coupled to the second output node of the preset voltage conversion circuit.

6. The photovoltaic module power optimization circuit according to claim 1, wherein a preset voltage conversion circuit is defined in the multi-stage voltage conversion circuit corresponding to any one photovoltaic module; wherein

A circuit breaking module is arranged between a second input node of the preset voltage conversion circuit and the negative pole of a battery string uniquely corresponding to the preset voltage conversion circuit; and

in the multi-stage voltage conversion circuit corresponding to any one photovoltaic module, the second output nodes of the other voltage conversion circuits except the preset voltage conversion circuit are connected to the negative electrode of the battery string uniquely corresponding to the other voltage conversion circuits through the circuit breaking module.

7. A communication method of a photovoltaic module power optimization circuit is provided, any one photovoltaic module is provided with a plurality of battery strings, and the communication method is characterized in that in the photovoltaic module power optimization circuit, each photovoltaic module is provided with a plurality of voltage conversion circuits with the number consistent with that of the battery strings, wherein in the multi-voltage conversion circuit corresponding to any one photovoltaic module: each stage of voltage conversion circuit is used for independently performing maximum power tracking on a corresponding battery string in any one photovoltaic module; the multi-stage voltage conversion circuits corresponding to any one photovoltaic module are connected in parallel, so that the voltages output by the multi-stage voltage conversion circuits are output to an output capacitor corresponding to the any one photovoltaic module together;

a plurality of photovoltaic modules are connected in series to form a battery pack string, output capacitors corresponding to the photovoltaic modules in each battery pack string are connected in series with each other through a transmission line, and a control switch connected in series with the output capacitors is arranged between a first end and a second end of one output capacitor of a multi-stage voltage conversion circuit corresponding to each photovoltaic module;

when the multi-stage voltage conversion circuit configured by any one specified photovoltaic module sends a carrier signal to the transmission line to perform communication:

one processor of the appointed photovoltaic component configuration drives the control switch connected with the output capacitor corresponding to the appointed photovoltaic component in series at least once to be switched off, and the processors of the other photovoltaic components except the appointed photovoltaic component in the battery pack string are respectively configured to drive the corresponding control switches to be switched on, so that a propagation path of the carrier signal is formed;

when the control switch arranged on the multi-stage voltage conversion circuit corresponding to the specified photovoltaic module is turned off, any specified circuit in the multi-stage voltage conversion circuits corresponding to the specified photovoltaic module couples excitation pulses jumping between high and low levels onto the transmission line as a carrier signal, and the excitation pulses are derived from: the pulse width modulation signal used for driving the specified circuit forces the voltage output by the specified circuit to have step change along with the frequency of the pulse width modulation signal, and the output step voltage is regarded as an excitation pulse.