CN108880460B - Step-up and step-down voltage converter for photovoltaic module and voltage modulation method - Google Patents

Abstract

The invention relates to a voltage boosting and reducing type voltage converter and a voltage modulation method for photovoltaic modules, wherein each photovoltaic module is provided with a voltage converter for executing maximum power point tracking and outputs the voltage of the photovoltaic module after voltage conversion; wherein: when the difference value between the output voltage and the input voltage of the voltage converter exceeds a preset value, the voltage converter works in a step-down or step-up working state; when the difference value between the output voltage and the input voltage of the voltage converter is not higher than the preset value, the voltage converter works in a voltage boosting and reducing working state. The voltage converter for the voltage boosting and reducing type of the photovoltaic module can be used for voltage modulation of the photovoltaic module voltage in the array according to actual conditions on the premise of realizing voltage reduction and voltage boosting in the application occasions containing the photovoltaic cells.

Description

Step-up and step-down voltage converter for photovoltaic module and voltage modulation method

Technical Field

The invention mainly relates to the field of photovoltaic power generation, in particular to a buck-boost type voltage converter for a photovoltaic module on the premise of realizing buck and boost in an application occasion containing a photovoltaic cell, which can determine to modulate the voltage of the photovoltaic module in an array according to actual conditions.

Background

One of the most important links in the field of photovoltaic power generation, except for an inverter, is voltage conversion, which is one of core circuits that perform voltage conversion from direct current to direct current, and mainly aims to convert the voltage of a battery from an original value that is easy to fluctuate to a desired voltage value. This involves boosting or stepping down the voltage of the battery, etc., raising or reducing the original photo-converted voltage of the battery according to the actual demand, and then inverting and connecting the obtained desired dc voltage. The field of photovoltaic power generation is increasingly emphasized by developed and developing countries, because almost every country and region faces the problem of increasingly worsening resource and environment, especially the countries or regions with underdeveloped economy are urgently oriented to develop economic purposes, and the negative environmental problems caused by industrialization and high energy consumption are easier to ignore. In the current photovoltaic power generation system, in order to ensure the safe and reliable operation of the power generation system, various potential threats need to be discovered in time: for example, the hot spot effect caused by shadow shielding is a negative threat, which may cause some batteries to be converted from a power supply into a load to cause the battery panel to be heated to be burnt, and the real-time accurate monitoring of the working parameters such as the voltage, the current, the power, the temperature and the power generation amount of the photovoltaic battery 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 are easily transmitted to a power line which provides photovoltaic voltage by taking the power line carrier as communication data, and then the real-time parameters of the photovoltaic cell can be acquired by decoding a carrier signal from the power line.

The main objectives of the present application are: because a plurality of batteries are connected in series to form a string in the application occasion of the photovoltaic battery, the actual voltage of the string is provided for the inverter to carry out inversion grid connection, on the premise of realizing that each photovoltaic battery is boosted or reduced in voltage or both, the working parameters of the photovoltaic battery are extracted and then analyzed, and the photovoltaic battery with potential faults is found in time so as to provide a basis for executing corresponding decisions. Moreover, according to the cascade voltage requirement, a voltage modulation mode of boosting or reducing or both of boosting and reducing can be selected to achieve reasonable selection of the cell voltage, and maximum power point tracking of the assembly is synchronously performed, so that the generating efficiency of each photovoltaic cell is maximized.

Disclosure of Invention

In one embodiment, the present invention discloses a buck-boost voltage converter for photovoltaic modules, each string providing a string voltage being provided with a plurality of photovoltaic modules connected in series with each other, wherein: each photovoltaic module is provided with a voltage converter for executing maximum power point tracking, and the voltage converter outputs the voltage of the photovoltaic module after voltage conversion; and: when the difference value between the output voltage and the input voltage of the voltage converter exceeds a preset value, the voltage converter works in a step-down or step-up working state; when the difference value between the output voltage and the input voltage of the voltage converter is not higher than the preset value, the voltage converter works in a voltage boosting and reducing working state.

The aforesaid a buck-boost type voltage converter for photovoltaic module, buck-boost type voltage converter includes: first and second input terminals coupled to the positive and negative electrodes of the photovoltaic module for capturing input voltage, first and second output terminals for providing output voltage; wherein the first and second switches of the buck conversion circuit are connected in series between the first and second input terminals; the third switch and the fourth switch of the boost conversion circuit are connected in series between the first output end and the second output end; an inductor is arranged between a first interconnection node connected with the first switch and the second interconnection node connected with the third switch and the fourth switch.

The buck-boost voltage converter for the photovoltaic module comprises: the first driver for driving the first and second switches at least comprises: first and second output stage units generating first and second driving signals, respectively, the first and second driving signals driving the first and second switches, respectively; and a second driver for driving the third and fourth switches, comprising at least: and a third and a fourth output stage unit for generating a third and a fourth driving signal, respectively, for driving the third and the fourth switch, respectively.

The buck-boost voltage converter for the photovoltaic module comprises: a pair of output tubes of the first output stage unit are connected in series between the first bootstrap node and the first interconnection node, and the first capacitor is connected between the first bootstrap node and the first interconnection node; a pair of output tubes of the fourth output stage unit are connected in series between the second bootstrap node and the second interconnection node, and the second capacitor is connected between the second bootstrap node and the second interconnection node; the first input end and/or the first output end charge the first bootstrap node and the second bootstrap node in a unidirectional mode through a diode; and a pair of output tubes of the respective second and third output stage units are connected in series between the first input terminal and the reference ground potential or between the first output terminal and the reference ground potential.

The buck-boost voltage converter for the photovoltaic module comprises: when the input voltage is larger than the output voltage, so that the difference between the input voltage and the output voltage exceeds a preset value, and the buck-boost type voltage converter is forced to work in a buck mode: the processor controls the first and second driving signals generated by the first and second output stage units to be mutually complementary signals so as to alternately switch on the first and second switches to drive the buck conversion circuit to be effective; and the processor controls the third driving signal output by the third output stage unit to continuously turn off the third switch at this stage; and the processor controls the upper tube in a pair of output tubes of the fourth output stage unit to be switched on and the lower tube to be switched off, and the fourth switch is continuously switched on by maintaining the fourth driving signal by the charging voltage of the second capacitor.

The buck-boost voltage converter for the photovoltaic module comprises: when the input voltage is smaller than the output voltage, so that the difference between the input voltage and the output voltage exceeds a preset value, and the voltage boosting type voltage converter is forced to work in a boosting mode: the processor controls the third and fourth driving signals generated by the third and fourth output stage units to be mutually complementary signals so as to alternately switch on the third and fourth switches to drive the boost conversion circuit to be effective; the processor controls the upper tube of a pair of output tubes of the first output stage unit to be switched on and the lower tube of the pair of output tubes of the first output stage unit to be switched off at the stage, and the charging voltage of the first capacitor maintains the first driving signal to continuously switch on the first switch; and the processor controls the second driving signal output by the second output stage unit to continuously turn off the second switch.

The buck-boost voltage converter for the photovoltaic module comprises: when the difference between the input voltage and the output voltage is not higher than the preset value, the buck-boost type voltage converter is forced to work in the buck-boost mixed mode: the processor controls the third and fourth driving signals generated by the third and fourth output stage units to be mutually complementary signals so as to alternately switch on the third and fourth switches to drive the boost conversion circuit to be effective; the processor controls the first and second driving signals generated by the first and second output stage units to be complementary signals to each other at this stage so as to alternately turn on the first and second switches to drive the buck conversion circuit to be effective.

The buck-boost voltage converter for the photovoltaic module comprises: each photovoltaic module is provided with a processor for driving a matched voltage converter thereof; and the processor configured for each photovoltaic module synchronously monitors the working parameters of the photovoltaic module, and transmits the working parameters to the data acquisition end by the processor configured for each photovoltaic module so as to realize that the photovoltaic module is monitored.

The buck-boost voltage converter for the photovoltaic module comprises: the series connection of a plurality of photovoltaic modules in the string is that a series of voltage converters corresponding to each photovoltaic module are connected in series with each other: any one voltage converter receives the original voltage provided by the photovoltaic module uniquely corresponding to the voltage converter and outputs the voltage subjected to voltage conversion by the photovoltaic module uniquely corresponding to the voltage converter; or the same voltage converter receives the original voltage provided by the parallel connection of the group of photovoltaic modules and outputs the voltage after the voltage conversion of the parallel connection of the group of photovoltaic modules.

The buck-boost voltage converter for the photovoltaic module comprises: the series connection mode of a plurality of photovoltaic modules in the string group is that a series of power optimization circuits corresponding to the photovoltaic modules are connected with each other in series: receiving power provided by at least one group of photovoltaic modules by the same power optimization circuit, wherein the power optimization circuit is provided with a plurality of voltage converters which are consistent with the number of the photovoltaic modules in the at least one group of photovoltaic modules; wherein in a plurality of voltage converters corresponding to the at least one group of photovoltaic modules: each voltage converter is used for individually performing voltage conversion on a corresponding battery assembly in the at least one group of photovoltaic assemblies; and a plurality of voltage converters corresponding to the at least one group of photovoltaic modules are arranged to be connected in parallel, so that the voltages output by the voltage converters are jointly output on the output capacitance of one power optimization circuit corresponding to the at least one group of photovoltaic modules.

The buck-boost voltage converter for the photovoltaic module comprises: in a plurality of voltage converters in the power optimization circuit corresponding to the at least one group of photovoltaic modules: the first and second output terminals of each voltage converter are coupled to the first and second terminals of the output capacitor of one power optimization circuit corresponding to the at least one group of photovoltaic modules, respectively.

The buck-boost voltage converter for the photovoltaic module comprises: the power optimization circuits are connected in series, and the second end of the output capacitor of any previous power optimization circuit is coupled to the first end of the output capacitor of the adjacent next power optimization circuit; whereby when a plurality of stages of said power optimizing circuits are connected in series their respective output capacitances are connected in series with each other, the plurality of stages of said power optimizing circuits providing a total voltage equal to a sum of voltages on their respective output capacitances.

In another embodiment of the disclosure, a voltage modulation method for a buck-boost type voltage converter for a photovoltaic module is disclosed, wherein the first and second switches of the buck conversion circuit of the voltage converter are connected in series between the first and second input terminals thereof, the third and fourth switches of the boost conversion circuit of the voltage converter are connected in series between the first and second output terminals thereof, and an inductor is disposed between the first interconnection node connecting the first and second switches and the second interconnection node connecting the third and fourth switches, and each buck-boost type voltage converter is further provided with a processor for controlling the buck conversion circuit and the boost conversion circuit to perform voltage modulation;

the voltage modulation method comprises the following steps: when the input voltage is larger than the output voltage, the difference value between the input voltage and the output voltage exceeds a preset value, the processor controls the buck-boost type voltage converter to work in a buck mode to execute maximum power point tracking; when the input voltage is smaller than the output voltage, the difference value between the input voltage and the output voltage exceeds a preset value, the processor controls the voltage boosting type voltage converter to work in a boosting mode to execute maximum power point tracking; when the difference value between the input voltage and the output voltage is not higher than a preset value, the processor controls the buck-boost type voltage converter to work in a buck-boost mixed mode to execute maximum power point tracking;

wherein: the processor drives a first switch and a second switch of the buck conversion circuit by using a first driver, the first driver comprises a first output stage unit and a second output stage unit which respectively generate a first driving signal and a second driving signal under the triggering of the processor, and the first driving signal and the second driving signal are respectively used for driving the first switch and the second switch; and the processor drives the third switch and the fourth switch of the boost conversion circuit by using a second driver, the second driver comprises a third output stage unit and a fourth output stage unit which respectively generate a third driving signal and a fourth driving signal under the triggering of the processor, and the third driving signal and the fourth driving signal are respectively used for driving the third switch and the fourth switch.

The method comprises the following steps: a pair of output tubes of the first output stage unit are connected in series between the first bootstrap node and the first interconnection node, and the first capacitor is connected between the first bootstrap node and the first interconnection node; a pair of output tubes of the fourth output stage unit are connected in series between the second bootstrap node and the second interconnection node, and the second capacitor is connected between the second bootstrap node and the second interconnection node; a pair of output tubes of the second and third output stage units are connected in series between the first input end and the reference ground potential or between the first output end and the reference ground potential; wherein the first and second bootstrap nodes are charged from the first input terminal and/or the first output terminal in a unidirectional charging manner using a diode.

The method comprises the following steps: the voltage modulation method when the voltage converter operates in the buck mode further includes: the processor controls the first and second output stage units to output first and second driving signals which are complementary signals to each other so as to alternately turn on the first and second switches in each buck switching period; the processor controls a third driving signal output by the third output stage unit to continuously turn off the third switch; the processor controls the upper tube of the pair of output tubes of the fourth output stage unit to be switched on and the lower tube of the pair of output tubes of the fourth output stage unit to be switched off, and clamps the potential of the fourth driving signal at the charging voltage of the second capacitor, so that the fourth driving signal continuously switches on the fourth switch.

The method comprises the following steps: the voltage modulation method when the voltage converter operates in the boost mode further includes: the processor controls the third and fourth output stage units to output third and fourth driving signals which are complementary signals to each other so as to alternately turn on the third and fourth switches in each boost switching period; the processor controls a second driving signal output by the second output stage unit to continuously turn off the second switch; the processor controls the upper tube of the pair of output tubes of the first output stage unit to be switched on and the lower tube of the pair of output tubes of the first output stage unit to be switched off, and clamps the potential of the first driving signal to the charging voltage of the first capacitor, so that the first switch is continuously switched on by the first driving signal.

The method comprises the following steps: the voltage modulation method in the buck-boost mode of the voltage converter further includes: the processor controls the third and fourth output stage units to output third and fourth driving signals which are complementary signals to each other so as to alternately turn on the third and fourth switches in each boost switching period; and the processor controls the first and second output stage units to output the first and second driving signals which are complementary signals to each other so as to alternately turn on the first and second switches in each buck switching period.

According to the method and the device, the working parameters of the photovoltaic cell are extracted and then sent to the data acquisition end integrated with the decoder, and the photovoltaic cell with potential faults can be timely and effectively found so as to provide basis for executing corresponding decisions. Moreover, the voltage converter (i.e. optimizer) can be selected to be a voltage boost or buck converter or a voltage modulation mode of both according to the expected requirement of the cascade voltage to realize reasonable conversion of the cell voltage, and the maximum power point tracking of the photovoltaic module can be synchronously performed so as to realize maximization of the output power of each photovoltaic cell. The driver of each switch in the driving voltage converter designs an output stage circuit with strong driving capability, and misoperation caused by weak driving capability of the traditional driver is avoided.

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 an exemplary schematic diagram of a plurality of photovoltaic modules connected in series with one another in a common string of battery packs.

Fig. 2 is a schematic diagram of a set of voltage conversion circuits supplied with raw voltage by a set of photovoltaic cells in parallel.

Fig. 3 is a schematic diagram of a power optimization circuit for providing voltage to the same one by a group of photovoltaic cells in parallel.

Fig. 4 is a schematic diagram of a series connection of multiple power-optimized circuits with their respective output capacitors in series with each other.

Fig. 5 is an exemplary schematic diagram of the first driver and the second driver driving the buck and boost circuits, respectively.

Fig. 6 is an exemplary schematic diagram of a single buck converter circuit operating in a buck-boost voltage converter circuit.

Fig. 7 is an exemplary schematic diagram of a single boost converter circuit operating in a buck-boost type voltage converter circuit.

Fig. 8 is a schematic diagram of simultaneous operation of the step-up and step-down conversion circuits in the step-up and step-down voltage conversion circuit.

Detailed Description

The present invention will be described more fully hereinafter with reference to the accompanying examples, which are intended to illustrate and not to limit the invention, but to cover all those embodiments, which may be learned by those skilled in the art without undue experimentation.

In the field of photovoltaic power generation, a photovoltaic module or a photovoltaic cell PV is one of the core components of power generation, and a solar cell panel is divided into a monocrystalline silicon solar cell, a polycrystalline silicon solar cell, an amorphous silicon solar cell and the like in the direction of mainstream technology, so that the number of the battery modules adopted by a large-scale centralized photovoltaic power station is large, and the number of the battery modules adopted by a small-scale distributed household small-scale power station is relatively small. Long-term and durable monitoring of the panels is essential since silicon cells typically require a service life in the field of up to twenty or more years. Many internal and external factors cause the reduction of the power generation efficiency of the photovoltaic module, and factors such as manufacturing difference or installation difference between the photovoltaic modules themselves or shading or maximum power tracking adaptation cause low efficiency. Taking a typical shadow shielding as an example, if a part of photovoltaic modules is shielded by clouds, buildings, tree shadows, dirt and the like, the part of the photovoltaic modules can be changed into a load by a power supply and does not generate electric energy any more, the local temperature of the photovoltaic modules in places with serious hot spot effect may be higher, and some of the photovoltaic modules even exceed 150 ℃, so that the local area of the photovoltaic modules is burnt or forms a dark spot, welding spots are melted, packaging materials are aged, glass is cracked, corrosion and other permanent damages are caused, and the long-term safety and reliability of the photovoltaic modules are caused to be extremely hidden. 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. Whether centralized photovoltaic power plants or distributed small power plants, it is essential to judge and identify those components that have potential problems based on the operating parameter data collected for the photovoltaic components.

In the field of photovoltaic power generation, photovoltaic modules or photovoltaic cells need to be connected in series to form a cell string, and then the cell string is connected in parallel to supply power to power equipment such as a combiner box or an inverter, so that the installation of the modules or the cells is required to be absolutely safe. If the photovoltaic modules have abnormal conditions such as over-temperature, over-voltage or over-current, the abnormal photovoltaic modules are required to be actively triggered to be turned off, and when the abnormal photovoltaic modules exit from the abnormal state and return to the normal state, the abnormal photovoltaic modules are required to be connected again, so that absolute safety is also required. In addition, in some occasions, the generated energy of the component needs to be detected or the output power condition needs to be monitored, which is the basis for judging the quality of the component, for example, if the generated energy of the component is obviously reduced, an abnormal event of power generation is likely to occur and is shielded by bird droppings, dust, buildings, tree shadows, clouds and the like, and measures such as cleaning batteries or changing the installation direction are needed. As known to those skilled in the art, a monocrystalline silicon solar cell, a polycrystalline silicon solar cell, an amorphous silicon solar cell, and the like are materials whose characteristics are easily degraded, and it is essential to monitor the degradation degree of a module, which is very important for determining the quality of a battery. The problems are that: we do not know how to discriminate in a large array of components those components are anomalous and those components are normal, and the following will address this problem. Many times, the battery or the component with poor quality needs to be directly judged in the installation stage, the battery with the quality defect is never allowed to be assembled/installed in the photovoltaic battery array, otherwise, the battery with the quality problem enters the photovoltaic battery array to cause low power generation efficiency of the whole array, and worse, the abnormal voltage value or current value of one or more problem batteries can cause damage to the whole battery string group, so that great loss is caused.

Referring to fig. 1, in order to achieve these predetermined objectives, the power optimization circuit/device integrated with a communication function according to the present application, which is referred to later, may reflect all operating parameters of the photovoltaic cells onto the power line by using power carriers, and provides a suitable solution for the photovoltaic power station to perform fault alarm, fault fast location, etc. on the cells, and is suitable for grid-connected or off-grid photovoltaic power generation systems of different scales. Especially, many battery anomalies can be found in the installation stage of the battery to avoid the problem battery and install the battery into the photovoltaic battery array, and the improvement of the battery safety level in the installation stage is one of the measures of the application. The carrier sending module CSG 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 power generation amount of the photovoltaic cell PV by using a collection module not shown in the figure, it is noted that the collection module for collecting these operating parameters belongs to the prior art, any existing scheme capable of collecting these operating parameters of the cell is suitable for this application, and this application does not separately explain the existing collection modules such as current, voltage, and temperature. In the embodiment of fig. 1, the first input terminal of the first stage voltage conversion circuit BS1 is connected to the positive terminal of the photovoltaic cell PV1 and the second input terminal of the first stage voltage conversion circuit BS1 is connected to the negative terminal of the photovoltaic cell PV1, and the voltage conversion circuit BS1 outputs a stable voltage between its own first node/first output terminal N1 and second node/second output terminal N2, i.e. the first stage voltage conversion circuit BS1 extracts the photovoltaic voltage generated by the photovoltaic cell PV1 through the photovoltaic effect between the first input terminal and the second input terminal. In the alternative embodiment described in the present application, the branch of the carrier transmitting module CSG is directly connected between the first node N1 and the second node N2, but in the non-illustrated embodiment, if the other type of carrier transmitting module employs a carrier transmitting circuit with a coupling transformer, the other type of carrier transmitting module need not be connected between the first node N1 and the second node N2, and in this case, the secondary winding of the coupling transformer included in the other type of carrier transmitting module is connected between the series connection line LAN and the first output terminal of the voltage converting circuit BS1, or between the series connection line LAN and the second output terminal of the voltage converting circuit BS1, and then the processor 200 inputs a carrier pulse from the primary winding of the coupling transformer, and can also deliver the carrier to the first node N1 or the second node N2. An alternative embodiment is to directly connect the carrier transmission module CSG between the first node N1 and the second node N2 according to the scheme of fig. 1 so as to directly inject the carrier signal at the first node N1 and the second node N2 at the same time. The above is considered from the point of view of the station transmitting the carrier signal, if the station is considered from the point of view of receiving the carrier signal, decoding/decoding of the carrier signal can be achieved on those connected lines LAN in fig. 1 which are connected to the first node N1 and/or the second node N2, using currently any carrier decoding module belonging to the known art. After the processor 200 associated with the photovoltaic cell PV1 transmits the data of the photovoltaic cell PV1 (for example, the data of various operating parameters of the cell) to the connection line LAN via various carrier transmission modules of any type, the other electronic devices can decode the carrier on the connection line LAN by using the DECODER. As one of the parties for sensing and decoding the Carrier Signal, the DECODER is generally provided with a sensor module and a band pass filter module, and a processing unit similar to MCU/DSP, etc., the power line passes through the sensor module (e.g., using a rogowski air coil sensor, etc.) to thereby detect the Carrier Signal on the transmission line LAN by the sensor module, and in order to accurately capture real Carrier data and shield noise, the band pass filter module further filters the Carrier Signal sensed by the sensor module to remove noise not within a specified frequency range, and instead, only those Carrier signals within the specified frequency range can represent the expected real Carrier Signal, and the processing unit receives the real Carrier Signal and decodes its Carrier data. The carrier sending module CSG is used for transmitting a power carrier signal to the connecting line LAN, the carrier signal can be converted into a binary code element according to various currently specified communication protocols to perform data information interaction, and the decoder or the data acquisition end detects the power carrier on the connecting line LAN and then performs decoding, so that the meaning of data or an instruction carried by the carrier signal sent by the carrier sending module CSG on the power line can be obtained. Note that the carrier wave form used by the processor 200 to broadcast/transmit data in this application is only one example, and the alternative in the industry may also select a wireless communication form such as wireless module WIFI or GPS or infrared-bluetooth (Blue-tooth) to achieve the same function. The data acquisition end for acquiring the battery data is integrated with a DECODER.

Referring to fig. 1, in practical applications, a large number of photovoltaic cells or photovoltaic modules PV are connected in series to form a battery string, assuming that a total of N levels of photovoltaic cells PV1, PV2 … … PVN are connected in series, where N is usually a natural number greater than 1, and the voltage of the battery string in the series is equal to: voltage V output by first stage photovoltaic cell PV1₁Plus the voltage V output by the second stage PV2₂Adding the voltage … output by the third stage PV3 to the voltage V output by the Nth stage PV PVN_NIs equal to V₁+ V₂+……V_N. The string voltage of the battery string is sent to the power equipment ESY such as the combiner box or the inverter. The series connection of the total N-level photovoltaic cells PV1 and PV2 … … PVN belongs to the abnormal events of power generation, wherein some photovoltaic modules generate less power without reason, or the voltage becomes lower or the temperature of the modules rises suddenly and is too high, and the like, and particularly the battery hot spot effect caused by shadow shielding is a negative threat, which may cause some cells to be converted from a power supply to a load to cause the panel to be heated to be burnt out by fire. Then, according to the representation characteristics of the respective operating parameters (preset data) of the photovoltaic cells PV1 and PV2 … … PVN in the string of the battery packs, at least whether a power generation abnormal event occurs to each photovoltaic module in the string of the battery packs can be judged.

Referring to fig. 1, each string has series connected photovoltaic cells PV1, PV2 … … PVN. In an alternative embodiment of the present application, each PV module or PV cell PV is configured with a voltage conversion circuit BS for performing voltage boosting or voltage dropping or voltage boosting, for example, the PV voltage generated by the first PV module PV1 in a cell string is DC/DC voltage converted by the first voltage conversion circuit BS1 to perform voltage boosting or voltage dropping, and the PV voltage generated by the second PV module PV2 is voltage converted by the second voltage conversion circuit BS2, … … up to the PV N of the nth stage PV module PVNThe photovoltaic voltage is voltage-converted by the nth stage voltage conversion circuit BSN to perform a voltage step-up and step-down function. It is only the voltage output by the voltage conversion circuit BS corresponding to each photovoltaic cell PV that can represent the actual voltage that the photovoltaic cell PV provides on the photovoltaic cell string. Assuming that the cell string group of any string is connected in series with the first-stage photovoltaic module PV1, the second-stage photovoltaic module PV2 … … to the Nth-stage photovoltaic module PVN, the first-stage voltage conversion circuit BS1 is used for performing a voltage lifting function on the photovoltaic voltage source of the first-stage photovoltaic cell PV1 to perform voltage conversion and output V₁… to the Nth stage voltage conversion circuit BSN perform a voltage step-up/step-down function on the photovoltaic voltage of the Nth stage photovoltaic cell PVN to perform voltage conversion and output V_NIt can be known that the total string level voltage provided across any string of battery strings is equal to: voltage V output from the first stage voltage conversion circuit BS1₁Adding the voltage V output by the second stage voltage conversion circuit BS2₂And the voltage V output by the third stage voltage conversion circuit BS3₃… to the voltage V accumulated to the output of the voltage conversion circuit BSN of the Nth stage_NThe operation result of the cascade voltage is equal to V₁+ V₂+……V_N. The voltage converting circuit BS or voltage converter is essentially a DC-DC converter. In addition to collecting data for the components, the processor 200 described above also outputs a PWM signal for driving the DC/DC converter. In fig. 1, the first-stage voltage conversion circuit BS1, the second-stage voltage conversion circuit BS2, and the nth-stage voltage conversion circuit BSN are connected in series by a serial connection LAN, and a serial voltage obtained by superimposing voltages output from the voltage conversion circuits BS1 to BSN on the transmission serial connection LAN is supplied to an electric power device ESY similar to a combiner box or an inverter for combining and inverting.

Referring to fig. 1, a photovoltaic module array is a basis for converting light energy into electric energy of a photovoltaic power generation system, and fig. 1 shows that a plurality of basic cell String strings are installed in the photovoltaic module array, and each cell String is formed by serially connecting a plurality of photovoltaic modules PV1 and PV2 … … connected in series, and each photovoltaic module or photovoltaic cell PV is provided with an optimization circuit for performing maximum power tracking MPPT, such as an MPPT optimization circuitThe photovoltaic voltage generated by the first photovoltaic module PV _1 is voltage-converted by the first voltage conversion circuit BS1 to perform power optimization, the photovoltaic voltage generated by the second photovoltaic module PV2 is voltage-converted by the second voltage conversion circuit BS2, and so on, and the voltage generated by the photovoltaic module PVN of the nth stage is thus voltage-converted by the voltage conversion circuit BSN of the nth stage to perform power optimization. The voltage output by the voltage conversion circuit BS corresponding to each photovoltaic cell PV can represent the actual voltage provided by the photovoltaic cell PV at the photovoltaic cell String, assuming that the photovoltaic cell String of any String is connected in series with the first stage photovoltaic module PV1, the second stage photovoltaic module PV1 … … and the photovoltaic module PVN of the nth stage, the first stage voltage conversion circuit BS1 is used for performing maximum power tracking on the photovoltaic voltage source of the first stage photovoltaic cell PV1 to perform voltage conversion and output V1₁And so on, until the nth stage voltage conversion circuit BSN is used for performing maximum power tracking on the photovoltaic voltage source of the nth stage photovoltaic cell PVN to perform voltage conversion and output V_NThe total String level voltage on any String of photovoltaic cell strings is: voltage V output from the first stage voltage conversion circuit BS1₁Adding the voltage V output by the second stage voltage conversion circuit BS2₂Then, the voltage … … output from the third-stage voltage conversion circuit BS _3 is added until the voltage V output from the nth-stage voltage conversion circuit BSN is added_NThe cascade voltage being equal to V₁+ V₂+……V_N. The voltage conversion circuit BS may generally employ a BOOST type BOOST, a BUCK type BUCK, or a BUCK-BOOST type BUCK-BOOST circuit. It should be emphasized that any scheme of maximum power tracking adopted for voltage increase and decrease of the photovoltaic cell in the prior art is applicable to the voltage conversion circuit of the present application, and in the industry, common maximum power tracking methods include a constant voltage method, a conductance increment method, a disturbance observation method, and the like.

Referring to fig. 2, the principle of implementing MPPT is first explained by taking a set of photovoltaic modules PV _ M and PV _ N as an example: the photovoltaic modules PV _ M and PV _ N supply power to voltage conversion circuits or voltage converters BS _ K and BS _ K-1, respectively, which perform maximum power tracking on the photovoltaic cells PV _ M and PV _ N. The conversion efficiency of photovoltaic cells is mainly affected by two aspects: the first is the intrinsic nature of the photovoltaic cell; the second is the surrounding use environment of the photovoltaic cell, such as the solar radiation intensity, load condition, temperature condition, and the like. Under different ambient conditions, the photovoltaic cell can operate at different and unique maximum power points. Therefore, for a power generation system of photovoltaic cells, the real-time optimal operation state of the photovoltaic cells under any illumination condition should be sought to convert the light energy into electric energy to the maximum extent.

Referring to fig. 2, the photovoltaic module PV _ M generates a desired output voltage while performing maximum power point tracking using the voltage conversion circuit BS _ K, the first input terminal NI1 of the voltage conversion circuit BS _ K being connected to the positive pole of the photovoltaic module PV _ M and the second input terminal NI2 of the voltage conversion circuit BS _ K being connected to the negative pole of the photovoltaic module PV _ M. It is further noted that the first output terminal NO1 of the voltage conversion circuit BS _ K is connected to an output capacitor C uniquely corresponding to the voltage conversion circuit BS _ K itself_OAnd a second output terminal NO2 of the voltage conversion circuit BS _ K is connected to an output capacitor C uniquely corresponding to the voltage conversion circuit BS _ K itself_OAnd a second end ND 2. The voltage conversion circuit BS _ K performs DC/DC voltage conversion on the voltage provided by the photovoltaic module PV _ M and performs maximum power tracking calculation synchronously, so that the DC output voltage outputted by the voltage conversion circuit BS _ K is generated between the first output terminal NO1 and the second output terminal NO2 of the voltage conversion circuit BS _ K, and the output voltage is applied to the output capacitor C of the voltage conversion circuit BS _ K_OBetween the first terminal ND1 and the second terminal ND2, an output capacitor C can be considered_ORespectively connected to the first output terminal NO1 and the second output terminal NO2 of the voltage conversion circuit BS _ K, i.e. corresponding to the output capacitor C_OConnected between the first output terminal N1 and the second output terminal N2 of the voltage conversion circuit BS itself of fig. 1. The first switch S1 and the second switch S2 of the Buck conversion circuit Buck in the voltage conversion circuit BS _ K are connected in series between the first input terminal NI1 and the second input terminal NI2, and the boost conversion in the voltage conversion circuit BS _ KThe third switch S3 and the second switch S4 of the circuit Boost are connected in series between the first output terminal NO1 and the second output terminal NO 2. Both the first switch S1 and the second switch S2 in the Buck circuit are connected to the first interconnection node NX1 and both the third switch S3 and the fourth switch S4 in the Boost circuit are connected to the second interconnection node NX2, then an inductance L is provided between the first interconnection node NX1 to which both the first and second switches S1-S2 are connected in the Buck-Boost circuit and the second interconnection node NX2 to which both the third and fourth switches S3-S4 are connected, and the second output NO2 and the second input NI2 may be directly coupled together and set their potentials to one reference potential REF, e.g. ground. An output capacitor C normally arranged between the first output NO1 and the second output NO2_OCorrespondingly, an input capacitor C is arranged between the first input NI1 and the second input NI2_INThe above-mentioned carrier transmitting module CSG transmitting the carrier may be connected between the first output terminal NO1 and the second output terminal NO2 of the voltage conversion circuit BS _ K. The direct driving capability of the processor 200 configured by the voltage conversion circuit BS _ K is generally weak, and it is not able to directly drive the switches such as MOSFET or IGBT, so we further utilize a first driver DR1 and a second driver DR2 with stronger driving capability, where the first driver DR1 is used to drive the first switch S1 and the second switch S2 in the Buck circuit, and the second driver DR2 is used to drive the third switch S3 and the fourth switch S4 in the Boost circuit. In the above, K is a natural number greater than 1.

Referring to fig. 2, the PV module PV _ N generates a desired output voltage while performing maximum power point tracking using the voltage conversion circuit BS _ K-1, the first input NI1 of the voltage conversion circuit BS _ K-1 is connected to the positive pole of the PV module PV _ N and the second input NI2 of the voltage conversion circuit BS _ K-1 is connected to the negative pole of the PV module PV _ N. Note that the first output terminal NO1 of the voltage conversion circuit BS _ K-1 is connected to an output capacitor C uniquely corresponding to the voltage conversion circuit BS _ K-1 itself_OAnd a second output terminal NO2 of the voltage conversion circuit BS _ K-1 are connected to an output capacitor C uniquely corresponding to the voltage conversion circuit BS _ K-1 itself_OAnd a second end ND 2. The voltage conversion circuit BS _ K-1 performs DC/DC voltage conversion on the voltage provided by the photovoltaic module PV _ N andthat is, the maximum power tracking calculation is performed synchronously, so that the DC output voltage outputted from the voltage converting circuit BS _ K-1 is generated between the first output terminal NO1 and the second output terminal NO2 of the voltage converting circuit BS _ K-1, that is, the output voltage is applied to the output capacitor C of the voltage converting circuit BS _ K-1_OBetween the first terminal ND1 and the second terminal ND2, we can consider the output capacitor C_ORespectively connected to the first output terminal NO1 and the second output terminal NO2 of the voltage conversion circuit BS _ K-1, i.e. corresponding to the output capacitor C_OConnected between the first output terminal N1 and the second output terminal N2 of the voltage conversion circuit BS itself in fig. 1. Whereby the first switch S1 and the second switch S2 of the Buck conversion circuit Buck in the voltage conversion circuit BS _ K-1 are connected in series between the first input terminal NI1 and the second input terminal NI2, and the third switch S3 and the second switch S4 of the Boost conversion circuit Boost in the voltage conversion circuit BS _ K-1 are connected in series between the first output terminal NO1 and the second output terminal NO 2. Both the first switch S1 and the second switch S2 of the Buck are connected to a first interconnection node NX1 and both the third switch S3 and the fourth switch S4 in the Boost are connected to a second interconnection node NX2, an inductance L is arranged between the first interconnection node NX1 to which both the first and the second switches S1-S2 are connected and the second interconnection node NX2 to which both the third and the fourth switches S3-S4 are connected in the Buck-Boost circuit, and the second output NO2 and the second input NI2 may be directly coupled together and set their potentials to a reference potential REF, e.g. ground. Similarly, an output capacitor C is usually provided in the voltage conversion circuit BS _ K-1 between the first output terminal NO1 and the second output terminal NO2_OCorrespondingly, an input capacitor C is arranged between the first input NI1 and the second input NI2 in the voltage conversion circuit BS _ K-1_INThe above-mentioned carrier transmission module CSG may be connected between the first output terminal NO1 and the second output terminal NO2 of the voltage conversion circuit BS _ K-1. The voltage conversion circuit BS _ K-1 and the voltage conversion circuit BS _ K are adjacent and connected in series, for example, the output capacitor C of the voltage conversion circuit BS _ K of the previous stage_OThe second terminal ND2 is connected to the output capacitor C of the next stage voltage conversion circuit BS _ K-1_OAnd a first end ND 1.

Referring to fig. 2, taking the processor 200 configured by the voltage conversion circuit BS _ K as an example, the processor 200 uses a first driver DR1 for driving the first switch S1 and the second switch S2, and uses a second driver DR2 for driving the third switch S3 and the second switch S4, in order to indirectly drive the first switch S1 and the second switch S2 of the Buck conversion circuit Buck in BS _ K and the third switch S3 and the second switch S4 of the Boost conversion circuit Boost in the voltage conversion circuit BS _ K. The first driver DR1 includes at least: a first output stage unit INV1 for generating a first driving signal SIG1, wherein the trigger signal output from the processor 200 to the first output stage unit INV1 is driven by the first output stage unit INV1 after the driving capability is enhanced by the first output stage unit INV1 to drive the first switch S1; the second output stage unit INV2 generates a second driving signal SIG2, and the trigger signal output by the processor 200 to the second output stage unit INV2 is boosted by the second output stage unit INV2 to drive the second switch S2, i.e. the first and second driving signals SIG1 and SIG2 are used to drive the first and second switches S1 and S2, respectively. Meanwhile, the second driver DR2 also includes at least: a third output stage INV3 for generating a third driving signal SIG3, wherein the trigger signal outputted from the processor 200 to the third output stage INV3 is driven by the third output stage INV3 to drive the third switch S3 after the driving capability of the third output stage INV3 is enhanced; and a fourth output stage unit INV4 generating a fourth driving signal SIG4, wherein the trigger signal output from the processor 200 to the fourth output stage unit INV4 is obtained by first enhancing the driving capability of the fourth output stage unit INV4 and then driving the fourth switch S2, i.e. driving the third switch S3 and the fourth switch S4 by the third driving signal SIG3 and the fourth driving signal SIG4, respectively. In summary, the first driver DR1 for driving the first and second switches S1-S2 includes at least: first and second output stage units INV1-INV2 generating first and second driving signals SIG1-SIG2, respectively, where the first and second driving signals SIG1-SIG2 are used to drive first and second switches S1-S2, respectively; the second driver DR2 for driving the third and fourth switches S3-S4 includes at least: third and fourth output stage units INV3-INV4 generating third and fourth drive signals SIG3-SIG4, where the third and fourth drive signals SIG3-SIG4 are used to drive third and fourth switches S3-S4, respectively.

Referring to fig. 2, in the first driver DR 1: the first output stage unit INV1 has an upper tube Q1 and a lower tube Q2 and the upper tube Q1 and the lower tube Q2 of the first output stage unit INV1 are similar to a totem pole structure or an inverter structure. As will be understood in conjunction with fig. 5 described below: the respective gate control terminals of the upper and lower transistors Q1 and Q2 serve as signal input terminals for receiving a trigger signal (e.g., a PWM pulse width modulation signal) generated by the processor 200, and a potential difference is applied between the first port of the upper transistor Q1 and the second port of the lower transistor Q2, and a node at which the second port of the upper transistor Q1 and the first port of the lower transistor Q2 are interconnected serves as an output terminal of the first output stage unit INV1 and generates the first drive signal SIG 1. Referring to fig. 5, a first port of the upper tube Q1 is connected to a first bootstrap node NBS1, and a second port of the lower tube Q2 is connected to a first interconnection node NX1 between the first switch S1 and the second switch S2. So a pair of output tubes Q1 and Q2 of the first output stage unit INV1 are connected in series between the first bootstrap node NBS1 and the first interconnection node NX1, and a first capacitor C is further provided_B1Is connected between the first bootstrapping node NBS1 and the first interconnect node NX 1. It is also shown that the first input NI1 of the voltage converting circuit BS _ K is coupled to the first bootstrapping node NBS1 via a diode D1, and the first output NO1 of the voltage converting circuit BS _ K is coupled to the first bootstrapping node NBS1 via a diode D2, where the charging is unidirectional, i.e. the anode of the diode D1 is coupled to the first input NI1, and the anode of the diode D2 is coupled to the first output NO1, and the cathodes of the diodes D1 and D2 are coupled to the first bootstrapping node NBS 1. Alternatively, it is also possible to connect D1 and resistor R1 in series between the first bootstrapping node NBS1 and the first input NI1, and/or to connect D2 and resistor R2 in series between the first bootstrapping node NBS1 and the first output NO 1. The first input NI1 and/or the first output NO1 charge the first bootstrap node NBS1 in a unidirectional manner through the diodes D1-D2. A zener diode may also be connected between the first bootstrap node NBS1 and the first interconnect node NX1, the anode of the zener diode being coupled to the first interconnect node NX1 and the cathode being coupled to the first bootstrap node NBS 1.

Referring to fig. 2, in the first driver DR 1: the second output stage unit INV2 has an upper tube Q3 and a lower tube Q4 and the upper tube Q3 and the lower tube Q4 of the second output stage unit INV2 are similar to a totem pole structure or an inverter structure. As will be understood in conjunction with fig. 5 described below: the respective gate control terminals of the upper and lower transistors Q3 and Q4 serve as signal input terminals for receiving a trigger signal (e.g., a PWM pulse width modulation signal) generated by the processor 200, and a potential difference is applied between the first port of the upper transistor Q3 and the second port of the lower transistor Q4, and a node at which the second port of the upper transistor Q3 and the first port of the lower transistor Q4 are interconnected serves as an output terminal of the second output stage unit INV2 and generates the second drive signal SIG 2. Referring to fig. 5, the first port of the upper tube Q3 is connected to the first input NI1 of the voltage conversion circuit BS _ K, and receives the input voltage VIN provided by the photovoltaic module PV _ M from the first input NI1, while the second port of the lower tube Q4 is connected to the reference potential REF having a potential equal to the negative potential of the photovoltaic module PV _ M. A pair of output tubes Q3 and Q4 of the second output stage unit INV2 are connected in series between the first input NI1 and the reference potential REF. Note that the first port of the upper tube Q3 in fig. 5 may also be connected to the first output terminal NO1 of the voltage conversion circuit BS _ K, i.e. receive the output voltage VOUT provided by the photovoltaic module PV _ M from the first output terminal NO1, while the second port of the lower tube Q4 is correspondingly connected to a reference potential REF equipotential with the cathode of the photovoltaic module PV _ M. The pair of output tubes Q3 and Q4 of the second output stage unit INV2 may also be connected in series between the first output terminal NO1 and the reference potential REF.

Referring to fig. 2, in the second driver DR 2: the third output stage unit INV3 has an upper tube Q5 and a lower tube Q6 and the upper tube Q5 and the lower tube Q6 of the third output stage unit INV3 are similar to a totem pole structure or an inverter structure. As will be understood in conjunction with fig. 5 described below: the respective gate control terminals of the upper and lower transistors Q5 and Q6 serve as signal input terminals for receiving a trigger signal (e.g., a PWM pulse width modulation signal) generated by the processor 200, and a potential difference is applied between the first port of the upper transistor Q5 and the second port of the lower transistor Q6, and a node at which the second port of the upper transistor Q5 and the first port of the lower transistor Q6 are interconnected serves as an output terminal of the third output stage unit INV3 and generates the third drive signal SIG 3. Referring to fig. 5, the first port of the upper tube Q5 is connected to the first input NI1 of the voltage conversion circuit BS _ K, and receives the input voltage VIN provided by the photovoltaic module PV _ M from the first input NI1, while the second port of the lower tube Q6 is connected to the reference potential REF having a potential equal to the negative potential of the photovoltaic module PV _ M. A pair of output tubes Q5 and Q6 of the third output stage unit INV3 are connected in series between the first input NI1 and the reference potential REF. Note that the first port of the upper tube Q5 in fig. 5 may also be connected to the first output terminal NO1 of the voltage conversion circuit BS _ K, i.e. receive the output voltage VOUT provided by the photovoltaic module PV _ M from the first output terminal NO1, while the second port of the lower tube Q6 is correspondingly connected to a reference potential REF equipotential with the cathode of the photovoltaic module PV _ M. The pair of output tubes Q5 and Q6 of the third output stage unit INV3 may also be connected in series between the first output terminal NO1 and the reference potential REF.

Referring to fig. 2, in the second driver DR 2: the fourth output stage unit INV4 has an upper tube Q7 and a lower tube Q8 and the upper tube Q7 and the lower tube Q8 of the fourth output stage unit INV4 are similar to a totem pole structure or an inverter structure. As will be understood in conjunction with fig. 5 described below: the respective gate control terminals of the upper and lower transistors Q7 and Q8 serve as signal input terminals for receiving a trigger signal (e.g., a PWM pulse width modulation signal) generated by the processor 200, and a potential difference is applied between the first port of the upper transistor Q7 and the second port of the lower transistor Q8, and a node at which the second port of the upper transistor Q7 and the first port of the lower transistor Q8 are interconnected serves as an output terminal of the fourth output stage unit INV4 and generates a fourth drive signal SIG 4. Referring to fig. 5, a first port of upper tube Q7 is connected to second bootstrap node NBS2, and a second port of lower tube Q8 is connected to a second interconnection node NX2 between third switch S3 and fourth switch S4, respectively. So a pair of output tubes Q7 and Q8 of the fourth output stage unit INV4 are connected in series between the second bootstrap node NBS2 and the second interconnection node NX2, and a second capacitor C is further provided_B2Is connected between the second bootstrapping node NBS2 and the second interconnect node NX 2. It is also shown that the first input NI1 of the voltage converting circuit BS _ K is coupled to the second bootstrap node NBS2 via a diode D4, and the first output NO1 of the voltage converting circuit BS _ K is coupled to the second bootstrap node NBS2 via a diode D3, where the charging is unidirectional, i.e. the anode of the diode D4 is coupled to the first input NI1 and the anode of the diode D3 is coupled to the first output NO1 and the cathodes of the diodes D3 and D4 are coupled to the second bootstrapping node NBS 2. Alternatively, it is also possible to connect D4 and resistor R1 in series between the second bootstrapping node NBS2 and the first input NI1, and/or D3 and resistor R2 in series between the second bootstrapping node NBS2 and the first output NO 1. The first input NI1 and/or the first output NO1 charge the second bootstrap node NBS2 in a unidirectional manner through the diodes D4-D3. A zener diode may also be connected between the second bootstrapping node NBS2 and the second interconnect node NX2, the anode of the zener diode being coupled to the second interconnect node NX2 and the cathode being coupled to the second bootstrapping node NBS 2.

In addition to this, unlike the embodiment of fig. 1, in which each photovoltaic module PV is configured to be provided with a corresponding one of the voltage conversion circuits BS for power optimization, an alternative embodiment is not configured to be provided with a corresponding one of the voltage conversion circuits BS for power optimization, but instead: in the series-connected String of cells String, several photovoltaic modules PV are jointly power-optimized by the same voltage converter circuit BS: at least one group of photovoltaic assemblies provides power for the same voltage conversion circuit in a parallel connection mode, and the voltage conversion circuit is used for synchronously executing maximum power tracking on the at least one group of photovoltaic assemblies. As in certain embodiments in place of fig. 1: at least one group of photovoltaic modules PV1 and PV2 supplies power to the same voltage conversion circuit BS1 in parallel, the voltage conversion circuit BS1 is used for synchronously performing maximum power tracking on a group of photovoltaic modules PV1 and PV2, namely, a first input NI1 of the voltage conversion circuit BS1 is simultaneously connected to the positive poles of the PV1 and PV2, and a second input NI2 of the voltage conversion circuit BS1 is simultaneously connected to the negative poles of the PV1 and PV 2. For another example in a specific embodiment: at least one group of photovoltaic modules PVM and PVN supplies power to the same voltage conversion circuit BSK in a parallel connection mode, K is a natural number larger than 1, the voltage conversion circuit BSK is used for synchronously carrying out maximum power tracking on the at least one group of photovoltaic modules PVM and PVN, a first input end NI1 of the voltage conversion circuit BSK is connected to the anodes of the PVM and PVN, and a second input end NI2 of the voltage conversion circuit BSK is connected to the cathodes of the PVM and PVN. Here, a group of PV modules is exemplified by using two PVMs and PVNs PV1 and PV2, and two PVMs and PVNs, and it is at least one group of a greater number of PV modules, which also provide power in parallel to the same voltage conversion circuit, and the voltage conversion circuit is used for synchronously performing maximum power tracking on the at least one group of PV modules.

Referring to fig. 1-2, the second output terminal NO2 of any preceding stage voltage converting circuit BS _ K is coupled to the first output terminal NO1 of the adjacent succeeding stage voltage converting circuit BS _ K-1 or the output capacitor C of any preceding stage voltage converting circuit BS _ K through the transmission line LAN by the multistage voltage converting circuits BS1, BS2, … … BSN, etc. connected in series_OIs correspondingly coupled to the output capacitor C of the adjacent succeeding voltage conversion circuit BS _ K-1 through the transmission line LAN_OAnd a first end ND 1. By analogy, the second output terminal NO2 of any preceding-stage voltage conversion circuit BS _ K +1 is coupled to the first output terminal NO1 of the adjacent succeeding-stage voltage conversion circuit BS _ K through the transmission line LAN, and so on. Finally, when the multistage voltage conversion circuits BS1 … … BSN and the like are connected in series, their respective output capacitances C_OAre connected in series with each other: that is, the output capacitor C of the voltage conversion circuit BS1_OAnd output capacitance C of BS2_OAnd output capacitance C of BS3_O… and BSK output capacitor C_OEtc. are connected in series by a transmission line LAN, so that the total cascade voltage supplied by the conversion circuits BS1, … … BSN, etc. is equal to the output capacitance C of each of the voltage conversion circuits BS1, BS2, … … BSN_OSuperimposed value of voltage on: output capacitance C substantially equal to BS1_OThe voltage across it plus the output capacitance C of BS2_OThe voltage across it plus the output capacitance C of BS3_OVoltage … … across the terminals until BSN's output capacitance C is added_OVoltage across, etc. In other words: the connection line LAN, which connects the voltage conversion circuits BS1 to BSN in series, provides a propagation path of the carrier wave in addition to a superposition path of the direct-current voltage.

Referring to fig. 3, at least one group of photovoltaic modules is configured to provide power to a power optimization circuit,the power optimization circuit is provided with a plurality of voltage conversion circuits, the number of the voltage conversion circuits is consistent with that of the photovoltaic modules in the at least one group of photovoltaic modules; wherein in a plurality of voltage conversion circuits corresponding to the at least one group of photovoltaic modules: each voltage conversion circuit is used for independently carrying out maximum power tracking on a corresponding battery pack in the at least one group of photovoltaic assemblies; and a plurality of voltage conversion circuits corresponding to the at least one group of photovoltaic modules are arranged to be connected in parallel, so that the voltages output by the voltage conversion circuits are jointly output on one output capacitor of the power optimization circuit corresponding to the at least one group of photovoltaic modules. For example, in specific embodiments: at least one group of photovoltaic modules PV _1 and PV _2 is configured to provide power to a power optimization circuit POC having a plurality of voltage conversion circuits BS _1 and BS _2 corresponding to the number (e.g. two) of photovoltaic modules in said at least one group of photovoltaic modules PV _1 and PV _2, the numbers here being merely illustrative and not limiting; wherein among the plurality of voltage conversion circuits BS _1 and BS _2 corresponding to the at least one group of photovoltaic modules PV _1 and PV _ 2: each voltage conversion circuit is used for individually performing maximum power tracking on a corresponding battery assembly in the at least one group of photovoltaic assemblies, namely a first voltage conversion circuit BS _1 is used for individually performing maximum power tracking on a corresponding battery assembly PV _1, and a second voltage conversion circuit BS _2 is used for individually performing maximum power tracking on a corresponding battery assembly PV _ 2; and a plurality of voltage conversion circuits BS _1 and BS _2 corresponding to the at least one group of photovoltaic modules PV _1 and PV _2 are arranged to be connected in parallel, so that the voltages output by BS _1 and BS _2 are output together on one output capacitance of the power optimization circuit corresponding to the at least one group of photovoltaic modules, namely equivalent to the voltage output by the voltage conversion circuits BS _1 and BS _2 is output together on one output capacitance C of the power optimization circuit POC corresponding to the at least one group of photovoltaic modules PV _1 and PV _2_OThe above. The voltage conversion circuits BS _1 and BS _2 employ BUCK-BOOST.

Referring to fig. 3, the second photovoltaic module PV _2 utilizes a second voltage conversion circuit BS _2 to generate the desired voltage output. Second voltage conversion circuit BS _2 in power optimization circuit POCIs connected to the positive pole of the PV module PV _2, and the second input NI2 of the second voltage conversion circuit BS _2 is connected to the negative pole of a corresponding one of the PV modules PV _2 uniquely corresponding to the BS _2 circuit. The first output terminal NO1 of the second voltage converting circuit BS _2 is connected to the output capacitor C uniquely corresponding to the power optimizing circuit POC_OAnd the second output terminal NO2 of the second voltage converting circuit BS _2 is connected to the output capacitor C uniquely corresponding to the power optimizing circuit POC_OAnd a second end ND 2. Referring to fig. 3, the first photovoltaic module PV _1 utilizes a first voltage conversion circuit BS _1 to generate a desired voltage output. The first input NI1 of the first voltage converting circuit BS _1 in the power optimizing circuit POC is connected to the positive pole of the PV module PV _1, and the second input NI2 of the first voltage converting circuit BS _1 is connected to the negative pole of the corresponding one of the PV modules PV _1 uniquely corresponding to the BS _1 circuit. Wherein the first output terminal NO1 of the first voltage converting circuit BS _1 is connected to the output capacitor C uniquely corresponding to the power optimizing circuit POC_OAnd the second output terminal NO2 of the first voltage conversion circuit BS _1 is connected to the output capacitor C uniquely corresponding to the power optimization circuit POC_OAnd a second end ND 2. In practice, the first terminal ND1 and the second terminal ND2 may be considered as a first output terminal and a second output terminal of the power optimization circuit POC having BS _1 and BS _2 for generating the output voltage. The maximum power tracking is mainly implemented in the industry by the processor 200 driving the switching tubes S1-S4 of BS _1 and BS _2, and the maximum power MPPT commonly used in the prior art includes a constant voltage method, a conductance increment method, a disturbance observation method, and the like.

Referring to fig. 4, for example, in a particular embodiment: at least one group of photovoltaic modules PV₂And PV₁Configured to provide power to a power optimization circuit POC having at least one group of photovoltaic modules PV₂And PV₁Multiple voltage conversion circuits BS with the same number (e.g. two) of photovoltaic modules₁And BS₂The quantities herein are merely illustrative and not restrictive; wherein, at least one group of photovoltaic modules PV₂And PV₁Corresponding multiple voltage conversion circuits BS₁And BS₂The method comprises the following steps: each voltage conversion circuit is used for individually performing maximum power tracking on a corresponding battery assembly in the at least one group of photovoltaic assemblies, i.e. the first voltage conversion circuit BS₁For aligning a corresponding cell module PV₁Performing maximum power tracking separately, and a second voltage conversion circuit BS₂For aligning a corresponding cell module PV₂Performing maximum power tracking alone; and with said at least one group of photovoltaic modules PV₂And PV₁Corresponding multiple voltage conversion circuits BS₁And BS₂Arranged in parallel connection such that the voltages of their respective outputs are output together on one output capacitance of the power optimization circuit corresponding to said at least one group of photovoltaic modules, i.e. the voltage conversion circuit BS₁And BS₂The output voltage is output together with the at least one group of photovoltaic modules PV₂And PV₁One output capacitor C of one power optimization circuit POC uniquely corresponding to the output capacitor C_OThe above. Service boundary pair assembly PV₂And PV₁Performing maximum power tracking in the industry is primarily driven BS by processor 200₁And BS₂Is realized by the switching tube IGBT or MOSFET. For example, in specific embodiments: at least one group of photovoltaic modules PV_NAnd PV_MConfigured to provide power to a power optimization circuit POC having at least one group of photovoltaic modules PV_NAnd PV_MMultiple voltage conversion circuits BS with consistent number (such as two) of photovoltaic modules₁And BS₂The quantities herein are merely illustrative and not restrictive; wherein at least one group of photovoltaic modules PV_NAnd PV_M1Corresponding multiple voltage conversion circuits BS₁And BS₂The method comprises the following steps: each voltage conversion circuit is used for individually performing maximum power tracking on a corresponding battery assembly in the at least one group of photovoltaic assemblies, i.e. the first voltage conversion circuit BS₁For aligning a corresponding cell module PV_MPerforming maximum power tracking separately, and a second voltage conversion circuit BS₂For aligning a corresponding cell module PV_NPerforming maximum power tracking alone; and with saidAt least one group of photovoltaic modules PV_MAnd PV_NCorresponding multiple voltage conversion circuits BS₁And BS₂Arranged in parallel connection such that the voltages of their respective outputs are output together on one output capacitance of the power optimization circuit corresponding to said at least one group of photovoltaic modules, i.e. the voltage conversion circuit BS₁And BS₂The output voltage is output together with the at least one group of photovoltaic modules PV_NAnd PV_MOne output capacitor C of one power optimization circuit POC only corresponding to one output capacitor C_OThe above.

See fig. 4, associated with a set of photovoltaic modules PV₂And PV₁Corresponding voltage conversion circuit BS₂And BS₁The method comprises the following steps: the first and second output terminals of each voltage conversion circuit are respectively coupled to the first and second terminals of the output capacitor of one power optimization circuit corresponding to the at least one group of photovoltaic modules, i.e. the first voltage conversion circuit BS₁Is coupled to the at least one group of photovoltaic modules PV respectively to the first and second output terminals NO1 and NO2 of said at least one group of photovoltaic modules PV₂And PV₁Output capacitor C of corresponding power optimization circuit POC_OA first end ND1 and a second end ND 2; and making the second voltage conversion circuit BS₂Is coupled to at least one group of photovoltaic modules PV, respectively, to first and second output terminals NO1 and NO2, respectively₂And PV₁Output capacitor C of corresponding power optimization circuit POC_OA first end ND1 and a second end ND 2. In another embodiment, with a set of photovoltaic modules PV_NAnd PV_MCorresponding voltage conversion circuit BS₂And BS₁The method comprises the following steps: the first and second output terminals of each voltage conversion circuit are respectively coupled to the first and second terminals of the output capacitor of one power optimization circuit corresponding to the at least one group of photovoltaic modules, i.e. the first voltage conversion circuit BS₁Is coupled to the at least one group of photovoltaic modules PV respectively to the first and second output terminals NO1 and NO2 of said at least one group of photovoltaic modules PV₂And PV₁Output capacitor C of corresponding power optimization circuit POC_OA first end ND1 and a second end ND 2; and making the second voltage conversion circuit BS₂First and second outputs ofThe outlets NO1 and NO2 are respectively coupled to a group of photovoltaic modules PV₂And PV₁Output capacitor C of corresponding power optimization circuit POC_OA first end ND1 and a second end ND 2. Finally, the power optimization circuits POC are connected in series, and the output capacitor C of any previous power optimization circuit POC_OIs coupled to the output capacitor C of the adjacent power optimization circuit POC of the next stage_OSo as to connect all output capacitors C of each of the power optimization circuits POC of the plurality of stages via a serial LAN_OAll connected in series. Their respective output capacitances C when the power-optimized circuits POC of a plurality of stages are connected in series_OAre connected in series, the total voltage provided by the power optimization circuits POC is equal to the output capacitance C of each power optimization circuit POC_OThe sum of the voltages on. Finally, their respective output capacitances C when the multi-stage power optimization circuits POC are connected in series_OAre connected in series with each other: i.e. the output capacitance C of the first stage POC_OAnd output capacitor C of second stage POC_OAnd output capacitor C of third stage POC_O… … and output capacitor C of K-th POC_OThe multistage optimization circuit POC provides a total voltage equal to the output capacitance C of the first stage POC, the second stage POC, … … to the K stage POC_OSuperimposed value of voltage on: output capacitance C substantially equal to first stage POC_OThe voltage at both ends is added with the output capacitor C of the second-stage POC_OThe voltage at both ends is added with the output capacitor C of the third stage POC_OVoltage … … at both ends and the output capacitor C of the K-th stage POC_OVoltage across, etc. In other words: the connection line LAN connects the POC of the first stage to the K-th stage in series, and it is noted that the connection line LAN provides a propagation path of the carrier wave in addition to a superposition path of the direct voltage. A data acquisition end (such as a combiner box or an inverter) for acquiring and analyzing parameters of the photovoltaic cell generally comprises a decoder, the decoder is provided with a sensor module, a band-pass filter module, a processing unit and the like, data of the data acquisition end can be sent to a cloud server or a computer or a mobile terminal, and the data can be specially used in a mobile phonePhotovoltaic cell parameters can be conveniently analyzed on APP.

The application discloses a method for synchronously realizing voltage modulation and monitoring of a photovoltaic cell based on the voltage-boosting and voltage-reducing type voltage converter, which comprises the following steps of: when each photovoltaic cell is in a first working state not tracked by the maximum power point or when each photovoltaic cell enters a second working state tracked by the maximum power point, the processor configured for each photovoltaic cell transmits the working parameters thereof to the acquisition end as the basis for diagnosing the photovoltaic cell, thereby realizing that the photovoltaic cell is monitored in the first or second working state. The application discloses a method for diagnosing a battery on the basis of monitored battery data, wherein one or more different types of operating parameters of each photovoltaic module PV1 … PVN in a battery string at least within a preset time period t are collected under a first operating state condition, and a set { F } of specified types of operating parameters of each photovoltaic module PV1 … PVN within the preset time period t₁、F₂、F₃…F_NComparing the operation parameters of the specified type of each individual photovoltaic module in the battery string within the preset time period, and at least judging whether each individual photovoltaic module in the battery string has a power generation abnormal event or not based on the comparison result. According to the set { F₁、F₂、F₃…F_NA high diagnostic threshold D for the specified type of operating parameter is calculated_UPPERAnd a low diagnostic threshold D_LOWERAnd judging whether the working parameters of the specified type monitored by each photovoltaic module in the battery pack string in the preset time period exceed the range of the high-level and low-level diagnosis threshold value and are not in the range D_LOWER-D_UPPERThe battery is warned to inform that the diagnosis result of the battery is abnormal. In other embodiments, for example: set of operating parameters { F) according to the specified type of each photovoltaic module in the string of battery packs within a preset time period t₁、F₂、F₃…F_NThe calculated mathematical mean M and the mathematical mean variance value S thereby determine the high and low diagnostic thresholds. High diagnostic threshold D_UPPERAnd low diagnostic thresholdD_LOWERIs a function of the mathematical mean M and the mathematical mean variance value S. Setting a high diagnostic threshold D_UPPEREqual to M + K S and a low diagnostic threshold D_LOWEREqual to M-K S, where K is a positive number, satisfies the condition.

。

。

In an alternative embodiment: in the first operating state, one or more different types of operating parameters of the individual PV modules PV1 … PVN of a battery string are collected at least over a predetermined time period t, which operating parameters typically include, for example, voltage, current, temperature, power or power generation, etc., parameter data to be monitored. The preset time period t may be a certain continuous time period in a day or may be several different time periods in a day. For example, a certain operating parameter of photovoltaic module PV1 is denoted F for a preset time period t-1 of the morning of a certain day₁Some operational parameter of module PV2 for a preset time period t-1 of the day at noon is denoted F₂And so on, … … the certain working parameter until a preset time period t-1 of the photovoltaic module PVN in the noon of a certain day is marked as F_NThis operating parameter, for example a voltage, results in a desired set of values, namely a set F of operating parameters of a given type for each photovoltaic module PV1 … PVN in the string of batteries, within a preset time period t₁、F₂、F₃…F_NAn operating parameter is, for example, a voltage value, and it is assumed that the voltage operating parameter of the photovoltaic module PV1 at a preset time period t-1 of the day is denoted as F₁The voltage operating parameter of photovoltaic module PV2 during a preset time period t-1 of the day is denoted F₂And so on, … … the voltage working parameter of the photovoltaic module PVN is assumed to be F in a preset time period t-1 in the morning of the day_NThen I amThe sets { F ] of the groups are analyzed within a preset time period t-1₁、F₂、F₃…F_NWhen the voltage of a certain component is found to be abnormal, the voltage working parameter of the photovoltaic component PV3 in the component is marked as F in the preset time period t-1 of the day at noon₃Suddenly higher than all other photovoltaic modules' voltages { F₁、F₂、F₄…F_NIf it is too large or too small, the voltage operating parameter of the PV3 at the preset time period t-1 of the day is considered to be F₃Due to an abnormality caused by some factor, the photovoltaic module PV3 may be shielded and the voltage may be reduced, or the photovoltaic module PV3 may have a low photoelectric conversion efficiency due to a quality problem. Under a first working state (for example, each photovoltaic cell is in an installation stage) that 'the photovoltaic cells are connected in series with each other to form a cell string group but do not enter a working state for tracking a maximum power point', the photovoltaic cells can find and screen fault cells in advance in the installation stage, and disaster consequences caused by the fact that the problem cells directly enter the array grid-connected power generation can be prevented.

Referring to fig. 6-8, the voltage modulation method of the voltage converter BS _ K in fig. 5 is: the processor 200 also synchronously monitors the values of the input voltage VIN and the output voltage VO, the first mode: when the input voltage VIN received by the first and second input terminals NI1-NI2 is greater than the output voltage VO generated by the first and second output terminals NO1-NO2, such that the difference between VIN and VO exceeds the preset value V-threshold, the processor 200 controls the buck-boost voltage converter BS _ K to operate in the buck mode to perform maximum power point tracking; in the second mode: when the input voltage VIN is smaller than the output voltage VO, such that a difference between VIN and VO exceeds a preset value V-threshold, the processor 200 controls the buck-boost voltage converter BS _ K to operate in the boost mode boost-mode to perform maximum power point tracking; the third mode: when the difference between the input voltage VIN and the output voltage VO is not higher than the predetermined value V-threshold, the processor 200 controls the buck-boost voltage converter to operate in the mixed mode of the buck-boost mode to perform maximum power point tracking. In three modes, the first capacitor C_B1And a second capacitor C_B2The respective charging voltages are clamped to follow the variation of the larger one of the input voltage VIN and the output voltage VO, i.e. the first capacitor C_B1And a second capacitor C_B2The voltages of the two capacitors are charged closer to the larger of the input voltage VIN and the output voltage VO. It is of no doubt known that the difference between the input voltage VIN and the output voltage VO is quite different in the three modes: letting the second capacitor C in buck mode_B2The charging voltage is larger than the output voltage VO, the difference between VIN and VO is larger than a preset value V-threshold, and the fourth switch S4 is continuously turned on in buck mode, which ensures that the second capacitor C is charged by the two conditions_B2The driving capability of the potential of S4 is sufficient to turn on S4; at the same time, let the first capacitor C in boost mode_B1The charging voltage is larger than the input voltage VIN, and the difference between VIN and VO is larger than the predetermined value V-threshold, and because the first switch S1 is continuously turned on in the boost mode, the two conditions clamp the first capacitor C_B1The driving capability of the potential of S1 is sufficient to turn on S1. In buck-boost mode, the difference between the input voltage VIN and the output voltage VO is not higher than a preset value V-threshold, and the first capacitor C_B1And a second capacitor C_B2The respective charging voltages are clamped to follow changes in the larger of the input VIN and output VO, which are dynamically charged closer to the larger of the input VIN and output VO: at this time, since none of the four switches S1-S4 can be continuously turned off, but S1 and S2 are alternately turned on and S3 and S4 are alternately turned on, and the difference between VIN and VO is not higher than the preset value V-threshold, the voltage of the two capacitors is not large relative to VIN and VO, that is, the voltage of the two capacitors in the buck-boost mode is different relative to the buck mode or the boost mode, and the difference between the dynamic charging voltages of the two capacitors relative to the smaller one of the input voltage VIN and the output voltage VO is lower than the preset value V-threshold: in detail, the first capacitor C_B1The difference between the dynamic charging voltage and the smaller one of VIN and VO (e.g., VIN or VO) is lower than a predetermined value V-threshold, and a second capacitor C_B2And the smaller of both VIN and VO (e.g., VIN or VO)VO) is lower than a preset value V-threshold, the first capacitor C is turned on while the switches S1 and S2 are alternately turned on_B1Does not cause the switch S1 to be turned on overtime, so-called hysteresis, and the second capacitor C when the switches S3 and S4 are turned on alternately_B2The dynamic charging voltage of (2) does not cause the switch S4 to switch on over time to generate a so-called hysteresis effect, and avoids dead zone failures defined when the switches S1 and S2 are alternately switched on and S3 and S4 are alternately switched on. Furthermore, the voltage converter BS _ K is actually switched between buck mode and boost mode and buck-boost mode during the voltage modulation process, and then the first capacitor C_B1And a second capacitor C_B2The respective charging voltage clamping modes are also switched transiently in accordance with the modulation mode of the voltage converter BS _ K. First capacitor C in buck mode_B1Is also larger than the output voltage VO, and its potential energy efficiently drives S1, the second capacitor C in boost mode_B2Is also greater than the input voltage VIN, its potential energy drives S4 efficiently.

Referring to fig. 6, the first mode: the voltage modulation method when the voltage converter BS _ K works in the step-down mode comprises the following steps: the processor 200 controls the first output stage unit INV1 of the first driver DR1 to output the first driving signal SIG1 coupled to the control terminal of the first switch S1, and the processor 200 controls the second output stage unit INV2 of the first driver DR1 to output the second driving signal SIG2 coupled to the control terminal of the second switch S2. The first and second output stage units output first and second driving signals SIG1-SIG2 which are complementary signals to each other so that the first and second switches S1-S2 are alternately turned ON in each Buck switching cycle, a Time S1-ON during which the first switch S1 is turned ON and a Time S1-OFF during which the first switch S1 is turned OFF in each Buck switching cycle, a Time S2-ON during which the second switch S2 is turned ON and a Time S2-OFF during which the second switch S2 is turned OFF in each Buck switching cycle, and a dead Time D-Time during which both switches S1-S2 are turned OFF is provided between the turn-ON of the first switch S1 and the turn-ON of the S2 of the second switch to prevent both switches S1-S2 from being directly turned ON at the same Time, which is a Buck section. And the processor 200 controls the third driving signal SIG3 output from the third output stage unit INV3 of the second driver DR2 to continuously turn off the third switch S3, for example, the processor 200 transmits to the third output stageThe trigger signal of the unit INV3 directly turns off the upper tube Q5 and turns on the lower tube Q6, and the control gate of the third switch S3 is low and turned off when NMOS is adopted. However, the processor 200 controls the upper tube Q7 of the pair of output tubes of the fourth output stage unit INV4 of the second driver DR2 to be turned on and the lower tube Q8 to be turned off, and if the fourth switch S4 adopts NMOS, the upper tube Q7 is turned on to clamp the potential of the fourth driving signal SIG4 to the second capacitor C_B2Charging voltage (C)_B1-C_B2The charging voltage is almost equal to the input voltage VIN), i.e. the second capacitor C_B2The charging voltage is directly applied between the gate control terminal and the source terminal of the fourth switch S4 through the upper tube Q7, so that the fourth switch S4 is continuously turned on by the potential of the fourth driving signal SIG4, and the Boost is forced to lose the boosting function at this stage. The current variation of the inductor L in fig. 6 is shown by the curve IL, and the output current to the load is shown by the smoother curve IOUT. It is noted that the first and second output stage units INV1 and INV2 of the first driver DR1 and the third and fourth output stage units INV3 and INV4 of the second driver DR2 have their respective upper and lower tubes not allowed to be turned on simultaneously, the processor synchronously triggers the lower tube to turn off if the upper tube is turned on for any output stage unit in the context, whereas the lower tube should be turned on if the upper tube is turned off.

Referring to fig. 7, the second mode: the voltage modulation method when the voltage converter BS _ K works in the boost mode step up comprises the following steps: at this time, the processor 200 controls the third output stage unit INV3 of the second driver DR2 to output the third driving signal SIG3 coupled to the control terminal of the third switch S3, and the processor 200 controls the fourth output stage unit INV4 of the second driver DR2 to output the fourth driving signal SIG4 coupled to the control terminal of the fourth switch S4. The processor controls the third and fourth output stage units to output the third and fourth driving signals SIG3-SIG4, which are complementary signals to each other, to alternately turn ON the third and fourth switches S3-S4 in each boost switching cycle, turn ON the third switch S3 for a time S3-ON and turn OFF the third switch S3 for a time S3-OFF in each boost switching cycle, turn ON the fourth switch S4 for a time S4-ON and turn OFF the fourth switch S4 for a time S4-OFF in each boost switching cycle, turn ON the third switch S3 and turn OFF the fourth switch S4 during the time S3S4 is turned on with a dead Time D-Time of both off to avoid the two switches S3-S4 being turned on directly at the same Time, which is the Boost portion. And the processor 200 controls the second driving signal SIG2 output by the second output stage unit INV2 of the first driver DR2 to continuously turn off the second switch S2, for example, the trigger signal transmitted by the processor 200 to the second output stage unit INV2 directly turns off the upper tube Q3 and turns on the lower tube Q4, and the control gate of the second switch S2 is turned off when NMOS is adopted. However, the processor 200 controls the upper tube Q1 of the pair of output tubes of the first output stage unit INV1 of the first driver DR2 to be turned on and the lower tube Q2 to be turned off, and if the first switch S1 adopts NMOS, the upper tube Q1 is turned on to clamp the potential of the first driving signal SIG1 to the first capacitor C_B1Charging voltage (C)_B1-C_B2The charging voltage is almost equal to the output voltage VO), i.e. the first capacitor C_B1The charging voltage is directly applied between the gate control terminal and the source terminal of the first switch S1 through the upper tube Q1, the first switch S1 is continuously turned on by the potential of the first driving signal SIG1, and at this stage, Buck is forced to lose the voltage reduction function. In fig. 7, the current variation of the inductor L in the boost mode is shown by the curve IL, and the output current to the load is shown by the smoother curve IOUT.

Referring to fig. 7, the third mode: the voltage modulation method in the mode that the voltage converter BS _ K operates in buck-boost mode further includes: the processor 200 controls the first output stage unit INV1 of the first driver DR1 to output the first driving signal SIG1 coupled to the control terminal of the first switch S1, and the processor 200 controls the second output stage unit INV2 of the first driver DR1 to output the second driving signal SIG2 coupled to the control terminal of the second switch S2. The first and second output stage units output first and second driving signals SIG1-SIG2 which are complementary signals to each other so that the first and second switches S1-S2 are alternately turned ON in each Buck switching cycle, the time S1-ON when the first switch S1 is turned ON and the time S1-OFF when the first switch S1 is turned OFF in each Buck switching cycle in fig. 8, and the time S2-ON when the second switch S2 is turned ON and the time S2-OFF when the second switch S2 is turned OFF in each Buck switching cycle, and a dead time during which both switches S1-S2 are turned OFF is provided between the turning ON of the first switch S1 and the turning ON of the S2 of the second switch to prevent both switches S1-S2 from being directly turned ON at the same time, which is a so-called operating mode of the Buck section. And at this time, the processor 200 also controls the third output stage unit INV3 of the second driver DR2 to output the third driving signal SIG3 coupled to the control terminal of the third switch S3, and the processor 200 controls the fourth output stage unit INV4 of the second driver DR2 to output the fourth driving signal SIG4 coupled to the control terminal of the fourth switch S4. The processor 200 controls the third and fourth driving signals SIG3-SIG4, which are complementary signals to each other, output from the third and fourth output stage units to alternately turn ON the third and fourth switches S3-S4 in each Boost switching cycle, S3-ON for the time the third switch S3 is turned ON and S3-OFF for the time the third switch S3 is turned OFF in each Boost switching cycle, S4-ON for the time the fourth switch S4 is turned ON and S4-OFF for the time the fourth switch S4 is turned OFF in each Boost switching cycle, and a dead time during which both switches are turned OFF is provided between the turning ON of the third switch S3 and the turning ON of the S4 of the fourth switch to prevent the two switches S3-S4 from being directly turned ON at the same time, which is an operation mode of the Boost portion. For simplicity, the third mode is exemplified by an alternative of fig. 8: the first Phase1 is in the boost mode, the second Phase2 and the third Phase3 are in the buck mode, the current of the inductor L in the first Phase1 increases and remains almost constant in the second Phase2, but the current of the inductor L in the third Phase3 decreases, and the abscissa T is time.

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 (13)

1. The utility model provides a buck-boost type voltage converter for photovoltaic module, each cluster that provides the cascade voltage all is provided with a plurality of photovoltaic module of establishing ties each other, its characterized in that:

each photovoltaic module is provided with a voltage converter for executing maximum power point tracking, and the voltage converter outputs the voltage of the photovoltaic module after voltage conversion;

wherein:

when the difference value between the output voltage and the input voltage of the voltage converter exceeds a preset value, the voltage converter works in a step-down or step-up working state;

when the difference value between the output voltage and the input voltage of the voltage converter is not higher than a preset value, the voltage converter works in a voltage boosting and reducing working state;

the buck-boost voltage converter includes: first and second input terminals coupled to positive and negative electrodes of the photovoltaic module for capturing input voltage, and first and second output terminals for providing output voltage; wherein:

the first switch and the second switch of the step-down conversion circuit are connected in series between the first input end and the second input end;

the third switch and the fourth switch of the boost conversion circuit are connected in series between the first output end and the second output end;

an inductor is arranged between a first interconnection node connected with the first switch and the second switch and a second interconnection node connected with the third switch and the fourth switch;

the first driver for driving the first and second switches at least comprises: first and second output stage units generating first and second driving signals, respectively, the first and second driving signals driving the first and second switches, respectively; and

the second driver for driving the third and fourth switches at least comprises: a third and a fourth output stage unit for generating a third and a fourth driving signal, respectively, for driving the third and the fourth switch, respectively;

a pair of output tubes of the first output stage unit are connected in series between the first bootstrap node and the first interconnection node, and the first capacitor is connected between the first bootstrap node and the first interconnection node;

a pair of output tubes of the fourth output stage unit are connected in series between the second bootstrap node and the second interconnection node, and the second capacitor is connected between the second bootstrap node and the second interconnection node;

the first input end and/or the first output end charge the first bootstrap node and the second bootstrap node in a unidirectional mode through a diode;

and a pair of output tubes of the respective second and third output stage units are connected in series between the first input terminal and the reference potential or between the first output terminal and the reference potential.

2. The buck-boost voltage converter for a photovoltaic module of claim 1, wherein:

when the input voltage is larger than the output voltage, so that the difference between the input voltage and the output voltage exceeds a preset value, and the buck-boost type voltage converter is forced to work in a buck mode:

the processor controls the first and second driving signals generated by the first and second output stage units to be mutually complementary signals so as to alternately switch on the first and second switches to drive the buck conversion circuit to be effective;

and at this stage

The processor controls a third driving signal output by the third output stage unit to continuously turn off the third switch; and

the processor controls the upper tube of the output tubes of the fourth output stage unit to be switched on and the lower tube of the output tubes of the fourth output stage unit to be switched off, and the fourth switch is continuously switched on by maintaining the fourth driving signal through the charging voltage of the second capacitor.

3. The buck-boost voltage converter for a photovoltaic module of claim 1, wherein:

when the input voltage is smaller than the output voltage, so that the difference between the input voltage and the output voltage exceeds a preset value, and the voltage boosting type voltage converter is forced to work in a boosting mode:

the processor controls the third and fourth driving signals generated by the third and fourth output stage units to be mutually complementary signals so as to alternately switch on the third and fourth switches to drive the boost conversion circuit to be effective;

and at this stage

The processor controls an upper tube in a pair of output tubes of the first output stage unit to be switched on and a lower tube to be switched off, and the first switch is continuously switched on by maintaining a first driving signal through the charging voltage of the first capacitor; and

the processor controls the second driving signal output by the second output stage unit to continuously turn off the second switch.

4. The buck-boost voltage converter for a photovoltaic module of claim 1, wherein:

when the difference between the input voltage and the output voltage is not higher than the preset value, the buck-boost type voltage converter is forced to work in the buck-boost mixed mode:

the processor controls the third and fourth driving signals generated by the third and fourth output stage units to be mutually complementary signals so as to alternately switch on the third and fourth switches to drive the boost conversion circuit to be effective;

and at this stage

The processor controls the first and second driving signals generated by the first and second output stage units to be mutually complementary signals so as to alternately turn on the first and second switches to drive the buck conversion circuit to be effective.

5. The buck-boost voltage converter for a photovoltaic module of claim 1, wherein:

each photovoltaic module is provided with a processor for driving a matched voltage converter thereof; and

the processor configured for each photovoltaic module synchronously monitors working parameters of the photovoltaic module, and the processor configured for each photovoltaic module transmits the working parameters to the data acquisition end to realize that the photovoltaic module is monitored.

6. The buck-boost voltage converter according to claim 1, wherein the plurality of photovoltaic modules in the string are connected in series such that their respective series of voltage converters are connected in series:

wherein

Any one voltage converter receives the original voltage provided by the photovoltaic module uniquely corresponding to the voltage converter and outputs the voltage subjected to voltage conversion by the photovoltaic module uniquely corresponding to the voltage converter; or

The same voltage converter receives the original voltage provided by the parallel connection of the group of photovoltaic modules and outputs the voltage after the voltage conversion of the parallel connection of the group of photovoltaic modules.

7. The buck-boost voltage converter according to claim 1, wherein the plurality of photovoltaic modules in the string are connected in series such that their corresponding series of power optimization circuits are connected in series:

receiving power provided by at least one group of photovoltaic modules by the same power optimization circuit, wherein the power optimization circuit is provided with a plurality of voltage converters which are consistent with the number of the photovoltaic modules in the at least one group of photovoltaic modules;

wherein

A plurality of voltage converters corresponding to the at least one group of photovoltaic modules, wherein: each voltage converter is used for individually performing voltage conversion on a corresponding battery assembly in the at least one group of photovoltaic assemblies; and

the plurality of voltage converters corresponding to the at least one group of photovoltaic modules are arranged to be connected in parallel, so that the voltages output by the voltage converters are output on the output capacitance of one power optimization circuit corresponding to the at least one group of photovoltaic modules in common.

8. The buck-boost voltage converter for a photovoltaic module of claim 7, wherein:

in a plurality of voltage converters in the power optimization circuit corresponding to the at least one group of photovoltaic modules:

the first and second output terminals of each voltage converter are coupled to the first and second terminals of the output capacitor of one power optimization circuit corresponding to the at least one group of photovoltaic modules, respectively.

9. The buck-boost voltage converter for a photovoltaic module of claim 8, wherein:

the power optimization circuits are connected in series, and the second end of the output capacitor of any previous power optimization circuit is coupled to the first end of the output capacitor of the adjacent next power optimization circuit;

whereby when a plurality of stages of said power optimizing circuits are connected in series their respective output capacitances are connected in series with each other, the plurality of stages of said power optimizing circuits providing a total voltage equal to a sum of voltages on their respective output capacitances.

10. A voltage modulation method based on a buck-boost voltage converter for photovoltaic modules is characterized in that each string for providing cascade voltage is provided with a plurality of photovoltaic modules which are connected in series, each photovoltaic module is provided with a voltage converter for executing maximum power point tracking, and the voltage converter outputs the voltage of the photovoltaic module after voltage conversion; wherein: when the difference value between the output voltage and the input voltage of the voltage converter exceeds a preset value, the voltage converter works in a step-down or step-up working state; when the difference value between the output voltage and the input voltage of the voltage converter is not higher than a preset value, the voltage converter works in a voltage boosting and reducing working state;

the first switch and the second switch of the buck conversion circuit in the voltage converter are connected in series between the first input end and the second input end of the buck conversion circuit, the third switch and the fourth switch of the boost conversion circuit in the voltage converter are connected in series between the first output end and the second output end of the boost conversion circuit, an inductor is arranged between a first interconnection node connected with the first switch and the second switch and a second interconnection node connected with the third switch and the fourth switch, and each buck-boost type voltage converter is also provided with a processor for controlling the buck conversion circuit and the boost conversion circuit to execute voltage modulation;

the voltage modulation method comprises the following steps:

when the input voltage is larger than the output voltage, the difference value between the input voltage and the output voltage exceeds a preset value, the processor controls the buck-boost type voltage converter to work in a buck mode to execute maximum power point tracking;

when the input voltage is smaller than the output voltage, the difference value between the input voltage and the output voltage exceeds a preset value, the processor controls the voltage boosting type voltage converter to work in a boosting mode to execute maximum power point tracking;

when the difference value between the input voltage and the output voltage is not higher than a preset value, the processor controls the buck-boost type voltage converter to work in a buck-boost mixed mode to execute maximum power point tracking;

wherein:

the processor drives a first switch and a second switch of the buck conversion circuit by using a first driver, the first driver comprises a first output stage unit and a second output stage unit which respectively generate a first driving signal and a second driving signal under the triggering of the processor, and the first driving signal and the second driving signal are respectively used for driving the first switch and the second switch; and

the processor drives a third switch and a fourth switch of the boost conversion circuit by using a second driver, the second driver comprises a third output stage unit and a fourth output stage unit which respectively generate a third driving signal and a fourth driving signal under the triggering of the processor, and the third driving signal and the fourth driving signal are respectively used for driving the third switch and the fourth switch;

a pair of output tubes of the first output stage unit are connected in series between the first bootstrap node and the first interconnection node, and the first capacitor is connected between the first bootstrap node and the first interconnection node;

a pair of output tubes of the fourth output stage unit are connected in series between the second bootstrap node and the second interconnection node, and the second capacitor is connected between the second bootstrap node and the second interconnection node;

a pair of output tubes of the second and third output stage units are connected in series between the first input end and the reference potential or between the first output end and the reference potential;

wherein the first and second bootstrap nodes are charged from the first input terminal and/or the first output terminal in a unidirectional charging manner using a diode.

11. The method of claim 10, wherein the voltage modulation method further comprises, when the voltage converter operates in the buck mode:

the processor controls the first and second output stage units to output first and second driving signals which are complementary signals to each other so as to alternately turn on the first and second switches in each buck switching period; and

the processor controls a third driving signal output by the third output stage unit to continuously turn off the third switch;

the processor controls the upper tube of the pair of output tubes of the fourth output stage unit to be switched on and the lower tube of the pair of output tubes of the fourth output stage unit to be switched off, and clamps the potential of the fourth driving signal at the charging voltage of the second capacitor, so that the fourth driving signal continuously switches on the fourth switch.

12. The method of claim 10, wherein the voltage modulation method further comprises, when the voltage converter operates in the boost mode:

the processor controls the third and fourth output stage units to output third and fourth driving signals which are complementary signals to each other so as to alternately turn on the third and fourth switches in each boost switching period; and

the processor controls a second driving signal output by the second output stage unit to continuously turn off the second switch;

the processor controls the upper tube of the pair of output tubes of the first output stage unit to be switched on and the lower tube of the pair of output tubes of the first output stage unit to be switched off, and clamps the potential of the first driving signal to the charging voltage of the first capacitor, so that the first switch is continuously switched on by the first driving signal.

13. The method of claim 10, wherein the voltage modulation method in the buck-boost mode further comprises:

the processor controls the third and fourth output stage units to output third and fourth driving signals which are complementary signals to each other so as to alternately turn on the third and fourth switches in each boost switching period; and

the processor controls the first and second output stage units to output first and second driving signals which are complementary signals to each other to alternately turn on the first and second switches in each buck switching period.

Images