CN111555260A - New-framework photovoltaic submodule based on capacitor-free voltage equalizer - Google Patents

New-framework photovoltaic submodule based on capacitor-free voltage equalizer Download PDF

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CN111555260A
CN111555260A CN202010397022.1A CN202010397022A CN111555260A CN 111555260 A CN111555260 A CN 111555260A CN 202010397022 A CN202010397022 A CN 202010397022A CN 111555260 A CN111555260 A CN 111555260A
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photovoltaic unit
photovoltaic
unit
switch tube
switch
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CN111555260B (en
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朱家骥
阚加荣
陈健
薛迎成
李郑斐
王贻鑫
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Yancheng Institute of Technology
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Yancheng Institute of Technology
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/10—Parallel operation of dc sources
    • H02J1/12—Parallel operation of dc generators with converters, e.g. with mercury-arc rectifier
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
    • H02S40/30—Electrical components
    • H02S40/36—Electrical components characterised by special electrical interconnection means between two or more PV modules, e.g. electrical module-to-module connection
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Abstract

The invention discloses a photovoltaic sub-module with a new framework based on a capacitor-free voltage equalizer, which connects a first photovoltaic unit, a second photovoltaic unit, a third photovoltaic unit, a fourth photovoltaic unit, a fifth photovoltaic unit, a sixth photovoltaic unit, a seventh photovoltaic unit, an eighth photovoltaic unit, a ninth photovoltaic unit, a tenth photovoltaic unit, an eleventh photovoltaic unit, a twelfth photovoltaic unit, a thirteenth photovoltaic unit, a fourteenth photovoltaic unit, a fifteenth photovoltaic unit and a sixteenth photovoltaic unit, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube, a sixth switch tube, a seventh switch tube and an eighth switch tube in a specific mode, so that a direct channel for differential energy transmission is provided, the step-by-step transmission of differential energy is avoided, and the energy acquisition rate of a photovoltaic system when power between the photovoltaic units is mismatched is improved, the power generation efficiency of the photovoltaic system is greatly improved.

Description

New-framework photovoltaic submodule based on capacitor-free voltage equalizer
Technical Field
The invention relates to the technical field of power electronic converters and control, in particular to a photovoltaic submodule with a new framework based on a capacitor-free voltage equalizer.
Background
The photovoltaic module is a device for converting solar energy into electric energy, and is used in occasions where solar energy is utilized for power generation, such as solar power plants, solar street lamps and the like. At present, the mainstream use form of photovoltaic is centralized power generation, that is, photovoltaic modules (PV modules) are connected in series and in parallel to obtain a photovoltaic array (PV array), and after enough high output voltage and current are ensured, a high-power centralized grid-connected inverter is used for Maximum Power Point Tracking (MPPT) and grid-connected control. But also has obvious defects that the input voltage with extremely wide variation range requires the adoption of devices with high voltage resistance and high on-resistance, and the utilization rate of the direct-current voltage of the inverter at the later stage is low, so that the efficiency of the inverter is low; in addition, due to the influence of factors such as local shadows, deviation of installation angles of the photovoltaic cell modules, dust, difference of electrical parameters and the like, voltage and current at the Maximum Power Point (MPP) output by each cell module in the photovoltaic array cannot be consistent, so that the output power of the photovoltaic array is limited by the photovoltaic module with the minimum power, the phenomenon is called power mismatch, the power loss reaches more than 30% in severe cases, and hot spots are generated on the photovoltaic module and the module is burnt out after long-term operation.
A common method for solving the problem of centralized power generation includes a photovoltaic direct current module (also referred to as a photovoltaic optimizer), a photovoltaic alternating current module (also referred to as a photovoltaic micro-inverter) and a Differential Power Processing (DPP) scheme, which can ensure that the photovoltaic modules (with a common power of about 200W) realize MPP operation to a certain extent, but is prone to the problem of low energy acquisition rate caused by power mismatch between photovoltaic units.
Disclosure of Invention
In order to overcome the current situation that the energy acquisition rate is low when the power of photovoltaic units in the traditional photovoltaic sub-module is mismatched, the invention provides a photovoltaic sub-module with a new framework based on a capacitor-free voltage equalizer, which changes the connection mode of the traditional photovoltaic sub-module, improves the energy acquisition rate of a photovoltaic system when the power of the photovoltaic units is mismatched, establishes a direct transmission channel of differential energy between the photovoltaic units with mismatched power, and greatly improves the power generation efficiency of the photovoltaic system; and the parasitic diffusion capacitor of the photovoltaic unit is used for replacing the capacitor in the traditional topology, so that the number of adopted devices is reduced, and the integration difficulty of photovoltaic sub-modules is reduced.
A new framework photovoltaic sub-module based on a capacitor-free voltage equalizer comprises a first photovoltaic unit, a second photovoltaic unit, a third photovoltaic unit, a fourth photovoltaic unit, a fifth photovoltaic unit, a sixth photovoltaic unit, a seventh photovoltaic unit, an eighth photovoltaic unit, a ninth photovoltaic unit, a tenth photovoltaic unit, an eleventh photovoltaic unit, a twelfth photovoltaic unit, a thirteenth photovoltaic unit, a fourteenth photovoltaic unit, a fifteenth photovoltaic unit, a sixteenth photovoltaic unit, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube, a sixth switch tube, a seventh switch tube and an eighth switch tube;
the negative electrode of the first photovoltaic unit is connected with the positive electrode of the second photovoltaic unit, the negative electrode of the third photovoltaic unit is connected with the positive electrode of the fourth photovoltaic unit, the negative electrode of the fifth photovoltaic unit is connected with the positive electrode of the sixth photovoltaic unit, the negative electrode of the seventh photovoltaic unit is connected with the positive electrode of the eighth photovoltaic unit, the negative electrode of the ninth photovoltaic unit is connected with the positive electrode of the tenth photovoltaic unit, the negative electrode of the tenth photovoltaic unit is connected with the positive electrode of the eleventh photovoltaic unit, the negative electrode of the sixteenth photovoltaic unit is connected with the positive electrode of the fifteenth photovoltaic unit, and the negative electrode of the fifteenth photovoltaic unit is connected with the positive electrode of the fourteenth photovoltaic unit; the negative electrode of the eleventh photovoltaic unit, the negative electrode of the twelfth photovoltaic unit, the positive electrode of the thirteenth photovoltaic unit and the positive electrode of the sixteenth photovoltaic unit are connected together; the source electrode of the first switching tube, the drain electrode of the second switching tube and the anode of the ninth photovoltaic unit are connected together; the source electrode of the third switching tube, the drain electrode of the fourth switching tube and the anode of the twelfth photovoltaic unit are connected together; the source electrode of the fifth switching tube, the drain electrode of the sixth switching tube and the negative electrode of the thirteenth photovoltaic unit are connected together; the source electrode of the seventh switching tube, the drain electrode of the eighth switching tube and the negative electrode of the fourteenth photovoltaic unit are connected together; the negative electrode of the second photovoltaic unit, the positive electrode of the third photovoltaic unit, the source electrode of the second switching tube and the drain electrode of the third switching tube are connected together; the negative electrode of the fourth photovoltaic unit, the positive electrode of the fifth photovoltaic unit, the source electrode of the fourth switching tube and the drain electrode of the fifth switching tube are connected together; and the negative electrode of the sixth photovoltaic unit, the positive electrode of the seventh photovoltaic unit, the source electrode of the sixth switching tube and the drain electrode of the seventh switching tube are connected together.
In an embodiment, the photovoltaic sub-module with the new architecture based on the capacitor-less voltage equalizer comprises a first photovoltaic cell group, a second photovoltaic cell group, a third photovoltaic cell group, a fourth photovoltaic cell group, a fifth photovoltaic cell group, a sixth photovoltaic cell group, a seventh photovoltaic cell group, an eighth photovoltaic cell group, a first switch group, a second switch group, a third switch group and a fourth switch group;
the first photovoltaic unit group comprises a first photovoltaic unit and a second photovoltaic unit; the second photovoltaic unit group comprises a third photovoltaic unit and a fourth photovoltaic unit; the third photovoltaic unit group comprises a fifth photovoltaic unit and a sixth photovoltaic unit; the fourth photovoltaic unit group comprises a seventh photovoltaic unit and an eighth photovoltaic unit; the fifth photovoltaic unit group comprises a ninth photovoltaic unit, a tenth photovoltaic unit and an eleventh photovoltaic unit; the sixth photovoltaic unit group comprises a twelfth photovoltaic unit; the seventh photovoltaic cell group comprises a thirteenth photovoltaic cell; the eighth photovoltaic unit group comprises a fourteenth photovoltaic unit, a fifteenth photovoltaic unit and a sixteenth photovoltaic unit; the first switch group comprises a first switch tube and a second switch tube; the second switch group comprises a third switch tube and a fourth switch tube; the third switch group comprises a fifth switch tube and a sixth switch tube, and the fourth switch group comprises a seventh switch tube and an eighth switch tube.
In one embodiment, the positive electrode of the first photovoltaic unit and the drain electrode of the first switching tube are connected together and used as the positive electrode of the whole photovoltaic submodule with the new framework; and the negative electrode of the eighth photovoltaic unit and the source electrode of the eighth switching tube are connected together and are used as the negative electrode of the whole photovoltaic submodule with the new framework.
In one embodiment, the driving signals of the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube are all pulse width modulation signals with a duty ratio of 50%, and the driving signals of any two adjacent switch tubes are complementary
The photovoltaic sub-module with the new framework based on the capacitor-free voltage equalizer is connected with the anode of the second photovoltaic unit through the cathode of the first photovoltaic unit, the cathode of the third photovoltaic unit is connected with the anode of the fourth photovoltaic unit, the cathode of the fifth photovoltaic unit is connected with the anode of the sixth photovoltaic unit, the cathode of the seventh photovoltaic unit is connected with the anode of the eighth photovoltaic unit, the cathode of the ninth photovoltaic unit is connected with the anode of the tenth photovoltaic unit, the cathode of the tenth photovoltaic unit is connected with the anode of the eleventh photovoltaic unit, the cathode of the sixteenth photovoltaic unit is connected with the anode of the fifteenth photovoltaic unit, and the cathode of the fifteenth photovoltaic unit is connected with the anode of the fourteenth photovoltaic unit; the negative electrode of the eleventh photovoltaic unit, the negative electrode of the twelfth photovoltaic unit, the positive electrode of the thirteenth photovoltaic unit and the positive electrode of the sixteenth photovoltaic unit are connected together; the source electrode of the first switching tube, the drain electrode of the second switching tube and the anode of the ninth photovoltaic unit are connected together; the source electrode of the third switching tube, the drain electrode of the fourth switching tube and the anode of the twelfth photovoltaic unit are connected together; the source electrode of the fifth switching tube, the drain electrode of the sixth switching tube and the negative electrode of the thirteenth photovoltaic unit are connected together; the source electrode of the seventh switching tube, the drain electrode of the eighth switching tube and the negative electrode of the fourteenth photovoltaic unit are connected together; the negative electrode of the second photovoltaic unit, the positive electrode of the third photovoltaic unit, the source electrode of the second switching tube and the drain electrode of the third switching tube are connected together; the negative electrode of the fourth photovoltaic unit, the positive electrode of the fifth photovoltaic unit, the source electrode of the fourth switching tube and the drain electrode of the fifth switching tube are connected together; the negative pole of the sixth photovoltaic unit, the positive pole of the seventh photovoltaic unit, the source electrode of the sixth switch tube and the drain electrode of the seventh switch tube are connected together, so that when each photovoltaic unit is subjected to power mismatch caused by different local shadows, aging degrees, installation angles and the like, the photovoltaic submodule with the new framework provides a direct channel for differential energy transmission, the step-by-step transmission of differential energy is avoided, the energy acquisition rate of a photovoltaic system is improved when the power mismatch occurs among the photovoltaic units, and the power generation efficiency of the photovoltaic system is greatly improved.
Drawings
Fig. 1 is a schematic front view of a conventional photovoltaic module;
FIG. 2 is a schematic diagram of internal wiring of a conventional photovoltaic module;
FIG. 3 is an equivalent circuit diagram of a photovoltaic unit;
FIG. 4 is a schematic structural diagram of a photovoltaic sub-module based on a new architecture of a capacitor-less voltage equalizer according to an embodiment;
FIG. 5 is a simulation model diagram of a new architecture photovoltaic sub-module based on a capacitor-less voltage equalizer according to an embodiment;
FIG. 6 is a simulation waveform diagram of a photovoltaic sub-module with a new architecture based on a capacitor-less voltage equalizer according to an embodiment;
FIG. 7 is a schematic diagram of a circuit mode of a photovoltaic sub-module based on a new architecture of a capacitor-less voltage equalizer according to an embodiment;
FIG. 8 is a current simulation waveform diagram for one embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.
The most common 72 photovoltaic cells (PV cells) on the market and the photovoltaic modules (PV modules) with an open circuit voltage of about 36V are schematically shown in fig. 1, the internal wiring diagram is shown in fig. 2, the open circuit voltage of each photovoltaic cell is about 0.6V, each 24 photovoltaic cells form a photovoltaic sub-module (PV submodule), and a bypass diode is connected to prevent the influence on other sub-modules when power is mismatched.
Common methods for solving the problem of centralized power generation include a photovoltaic direct current module (also called a photovoltaic optimizer), a photovoltaic alternating current module (also called a photovoltaic micro-inverter) and a Differential Power Processing (DPP) scheme, and the three schemes can ensure that the photovoltaic module (with common power of about 200W) realizes MPP operation, but also have the following problems:
1. the direct current module and the alternating current module both adopt two-stage circuit structures, and the two-stage conversion is a full power converter (FPP), so that the control is complex, the efficiency is low, and the cost is high; the bypass diode in the photovoltaic module causes the power output characteristic of the module to comprise a plurality of local peak values, so that the difficulty of the MPPT algorithm is increased;
although the DPP scheme belongs to partial power conversion (PPP), bypass diodes in modules can be removed, and power mismatch between photovoltaic sub-modules can be solved, in order to obtain a voltage matched with a post-converter or a load, an output voltage needs to be stabilized by a concentrated DC/DC converter, so that the DPP scheme still has the defects of complex structure and low efficiency;
3. considering from the smallest photovoltaic cell level, when the power is mismatched, the three schemes all cause the loss of energy output.
At present, the three schemes all have certain defects, and photovoltaic sub-modules are required to be re-integrated from the photovoltaic unit level, so that new photovoltaic modules are integrated. However, the existing new architecture technology based on the photovoltaic unit is in a starting stage, passive elements such as a capacitor and an inductor are needed in the integration process, and the integration difficulty is increased. The equivalent model of a photovoltaic unit has been perfected in recent years, with an equivalent circuit as shown in fig. 3, where CdThe capacitance represents the combined equivalent capacitance of the diffusion capacitance and the depletion layer capacitance of the photovoltaic unit, the diffusion capacitance occupies the main part near the maximum power point of the photovoltaic unit, and the depletion layer capacitance can be ignored. Relevant researches show that the capacitance value can reach mF level, the equivalent series resistance Rs is very small, and the influence on the output voltage of the photovoltaic unit is limited.
In order to thoroughly solve the problem of power among photovoltaic units in a photovoltaic systemThe problem of low energy acquisition rate caused by mismatch and the integration of photovoltaic units are facilitated, in one embodiment, a new architecture photovoltaic sub-module based on a capacitor-less voltage equalizer is constructed from a photovoltaic unit hierarchy, as shown in fig. 4, and the meaning of the symbol names in fig. 4 includes: PV + represents the output positive pole of the photovoltaic module; PV-represents the photovoltaic module output negative electrode; i isscRepresents a photovoltaic cell equivalent current source; ddRepresents a photovoltaic cell equivalent diode; cdRepresents the diffusion capacitance of the photovoltaic cell; rpRepresenting the equivalent parallel resistance of the photovoltaic unit; rsRepresenting the equivalent series resistance of the photovoltaic unit; PVS + represents the positive electrode of the photovoltaic sub-module with the new framework; PVS-represents the negative electrode of the photovoltaic submodule with the new framework; PV (photovoltaic)C1-PVC16Represents a first to a sixteenth photovoltaic unit; sC1-SC8Showing a first switching tube to an eighth switching tube; u. ofSC1-uSC8Representing the corresponding driving signals of the first switching tube to the eighth switching tube; i.e. iPVC1-iPVC8Representing currents flowing through the first to eighth photovoltaic cell groups; i isPVC1-IPVC8Represents an average value of currents flowing through the first to eighth photovoltaic cell groups. The structure stores energy by using the equivalent capacitor of the photovoltaic unit, eliminates passive elements in the structure, and realizes the transfer of differential energy by a capacitor-free voltage equalizer when the power of the photovoltaic unit is mismatched, thereby ensuring that the photovoltaic unit works at the respective maximum power point.
The photovoltaic sub-module with the new framework based on the capacitor-free voltage equalizer comprises a first photovoltaic unit, a second photovoltaic unit, a third photovoltaic unit, a fourth photovoltaic unit, a fifth photovoltaic unit, a sixth photovoltaic unit, a seventh photovoltaic unit, an eighth photovoltaic unit, a ninth photovoltaic unit, a tenth photovoltaic unit, an eleventh photovoltaic unit, a twelfth photovoltaic unit, a thirteenth photovoltaic unit, a fourteenth photovoltaic unit, a fifteenth photovoltaic unit, a sixteenth photovoltaic unit, a first switching tube, a second switching tube, a third switching tube, a fourth switching tube, a fifth switching tube, a sixth switching tube, a seventh switching tube and an eighth switching tube;
the negative electrode of the first photovoltaic unit is connected with the positive electrode of the second photovoltaic unit, the negative electrode of the third photovoltaic unit is connected with the positive electrode of the fourth photovoltaic unit, the negative electrode of the fifth photovoltaic unit is connected with the positive electrode of the sixth photovoltaic unit, the negative electrode of the seventh photovoltaic unit is connected with the positive electrode of the eighth photovoltaic unit, the negative electrode of the ninth photovoltaic unit is connected with the positive electrode of the tenth photovoltaic unit, the negative electrode of the tenth photovoltaic unit is connected with the positive electrode of the eleventh photovoltaic unit, the negative electrode of the sixteenth photovoltaic unit is connected with the positive electrode of the fifteenth photovoltaic unit, and the negative electrode of the fifteenth photovoltaic unit is connected with the positive electrode of the fourteenth photovoltaic unit; the negative electrode of the eleventh photovoltaic unit, the negative electrode of the twelfth photovoltaic unit, the positive electrode of the thirteenth photovoltaic unit and the positive electrode of the sixteenth photovoltaic unit are connected together; the source electrode of the first switching tube, the drain electrode of the second switching tube and the anode of the ninth photovoltaic unit are connected together; the source electrode of the third switching tube, the drain electrode of the fourth switching tube and the anode of the twelfth photovoltaic unit are connected together; the source electrode of the fifth switching tube, the drain electrode of the sixth switching tube and the negative electrode of the thirteenth photovoltaic unit are connected together; the source electrode of the seventh switching tube, the drain electrode of the eighth switching tube and the negative electrode of the fourteenth photovoltaic unit are connected together; the negative electrode of the second photovoltaic unit, the positive electrode of the third photovoltaic unit, the source electrode of the second switching tube and the drain electrode of the third switching tube are connected together; the negative electrode of the fourth photovoltaic unit, the positive electrode of the fifth photovoltaic unit, the source electrode of the fourth switching tube and the drain electrode of the fifth switching tube are connected together; and the negative electrode of the sixth photovoltaic unit, the positive electrode of the seventh photovoltaic unit, the source electrode of the sixth switching tube and the drain electrode of the seventh switching tube are connected together.
The photovoltaic sub-module with the new framework based on the capacitor-free voltage equalizer is connected with the anode of the second photovoltaic unit through the cathode of the first photovoltaic unit, the cathode of the third photovoltaic unit is connected with the anode of the fourth photovoltaic unit, the cathode of the fifth photovoltaic unit is connected with the anode of the sixth photovoltaic unit, the cathode of the seventh photovoltaic unit is connected with the anode of the eighth photovoltaic unit, the cathode of the ninth photovoltaic unit is connected with the anode of the tenth photovoltaic unit, the cathode of the tenth photovoltaic unit is connected with the anode of the eleventh photovoltaic unit, the cathode of the sixteenth photovoltaic unit is connected with the anode of the fifteenth photovoltaic unit, and the cathode of the fifteenth photovoltaic unit is connected with the anode of the fourteenth photovoltaic unit; the negative electrode of the eleventh photovoltaic unit, the negative electrode of the twelfth photovoltaic unit, the positive electrode of the thirteenth photovoltaic unit and the positive electrode of the sixteenth photovoltaic unit are connected together; the source electrode of the first switching tube, the drain electrode of the second switching tube and the anode of the ninth photovoltaic unit are connected together; the source electrode of the third switching tube, the drain electrode of the fourth switching tube and the anode of the twelfth photovoltaic unit are connected together; the source electrode of the fifth switching tube, the drain electrode of the sixth switching tube and the negative electrode of the thirteenth photovoltaic unit are connected together; the source electrode of the seventh switching tube, the drain electrode of the eighth switching tube and the negative electrode of the fourteenth photovoltaic unit are connected together; the negative electrode of the second photovoltaic unit, the positive electrode of the third photovoltaic unit, the source electrode of the second switching tube and the drain electrode of the third switching tube are connected together; the negative electrode of the fourth photovoltaic unit, the positive electrode of the fifth photovoltaic unit, the source electrode of the fourth switching tube and the drain electrode of the fifth switching tube are connected together; the negative pole of the sixth photovoltaic unit, the positive pole of the seventh photovoltaic unit, the source electrode of the sixth switch tube and the drain electrode of the seventh switch tube are connected together, so that when each photovoltaic unit is subjected to power mismatch caused by different local shadows, aging degrees, installation angles and the like, the photovoltaic submodule with the new framework provides a direct channel for differential energy transmission, the step-by-step transmission of differential energy is avoided, the energy acquisition rate of a photovoltaic system is improved when the power mismatch occurs among the photovoltaic units, and the power generation efficiency of the photovoltaic system is greatly improved.
In one embodiment, the new architecture photovoltaic sub-module based on the capacitor-less voltage equalizer comprises a first photovoltaic cell group, a second photovoltaic cell group, a third photovoltaic cell group, a fourth photovoltaic cell group, a fifth photovoltaic cell group, a sixth photovoltaic cell group, a seventh photovoltaic cell group, an eighth photovoltaic cell group, a first switch group, a second switch group, a third switch group and a fourth switch group;
the first photovoltaic unit group comprises a first photovoltaic unit and a second photovoltaic unit; the second photovoltaic unit group comprises a third photovoltaic unit and a fourth photovoltaic unit; the third photovoltaic unit group comprises a fifth photovoltaic unit and a sixth photovoltaic unit; the fourth photovoltaic unit group comprises a seventh photovoltaic unit and an eighth photovoltaic unit; the fifth photovoltaic unit group comprises a ninth photovoltaic unit, a tenth photovoltaic unit and an eleventh photovoltaic unit; the sixth photovoltaic unit group comprises a twelfth photovoltaic unit; the seventh photovoltaic cell group comprises a thirteenth photovoltaic cell; the eighth photovoltaic unit group comprises a fourteenth photovoltaic unit, a fifteenth photovoltaic unit and a sixteenth photovoltaic unit; the first switch group comprises a first switch tube and a second switch tube; the second switch group comprises a third switch tube and a fourth switch tube; the third switch group comprises a fifth switch tube and a sixth switch tube, and the fourth switch group comprises a seventh switch tube and an eighth switch tube.
The photovoltaic sub-module with the new framework and without the capacitor voltage equalizer comprises sixteen photovoltaic units and eight switching tubes, wherein the sixteen photovoltaic units are divided into eight photovoltaic unit groups, and the eight switching tubes are divided into four switching groups; the first photovoltaic unit group comprises a first photovoltaic unit and a second photovoltaic unit; the second photovoltaic unit group comprises a third photovoltaic unit and a fourth photovoltaic unit; the third photovoltaic unit group comprises a fifth photovoltaic unit and a sixth photovoltaic unit; the fourth photovoltaic unit group comprises a seventh photovoltaic unit and an eighth photovoltaic unit; the fifth photovoltaic unit group comprises a ninth photovoltaic unit, a tenth photovoltaic unit and an eleventh photovoltaic unit; the sixth photovoltaic unit group comprises a twelfth photovoltaic unit; the seventh photovoltaic unit group comprises a thirteenth photovoltaic unit; the eighth photovoltaic unit group comprises a fourteenth photovoltaic unit, a fifteenth photovoltaic unit and a sixteenth photovoltaic unit; the first switch group comprises a first switch tube and a second switch; the second switch group comprises a third switch tube and a fourth switch tube; the third switch group comprises a fifth switch tube and a sixth switch tube, and the fourth switch group comprises a seventh switch tube and an eighth switch tube.
In one embodiment, the positive electrode of the first photovoltaic unit and the drain electrode of the first switching tube are connected together and used as the positive electrode of the whole photovoltaic submodule with the new framework; and the negative electrode of the eighth photovoltaic unit and the source electrode of the eighth switching tube are connected together and are used as the negative electrode of the whole photovoltaic submodule with the new framework.
In one embodiment, the driving signals of the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube are all pulse width modulation signals with a duty ratio of 50%, and the driving signals of any two adjacent switch tubes are complementary.
In the embodiment, pulse width modulation signals with duty ratio of 50% are respectively applied to the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube to serve as driving signals, so that accurate control over a photovoltaic sub-module with a new framework based on a capacitor-free voltage equalizer can be realized, and a corresponding control process is effectively simplified.
Specifically, in the control method of the photovoltaic sub-module with the new architecture based on the capacitor-less voltage equalizer, the driving signal of each of the eight switching tubes is a PWM signal with a duty ratio of 50%, and any two adjacent switching tubes are complementary to each other, and the waveforms of the driving signals are as shown in fig. 5. When the first, third, fifth, and seventh switching tubes are turned on, the circuit mode of the photovoltaic sub-module based on the new architecture without the capacitor voltage equalizer is shown in fig. 6, where the mode includes six loops, which are:
1. the photovoltaic power generation system comprises a first photovoltaic unit group, a first switch tube, a fifth photovoltaic unit group, a sixth photovoltaic unit group and a third switch tube;
2. the photovoltaic power generation system comprises a first photovoltaic unit group, a second photovoltaic unit group, a third switching tube, a sixth photovoltaic unit group, a seventh photovoltaic unit group and a fifth switching tube;
3. a third photovoltaic unit group, a fifth switching tube, a seventh photovoltaic unit group, an eighth photovoltaic unit group and a seventh switching tube;
4. the photovoltaic power generation system comprises a first photovoltaic unit group, a second photovoltaic unit group, a first switching tube, a fifth photovoltaic unit group, a seventh photovoltaic unit group and a fifth switching tube;
5. the photovoltaic power generation system comprises a third photovoltaic unit group, a second photovoltaic unit group, a third switching tube, a sixth photovoltaic unit group, an eighth photovoltaic unit group and a seventh switching tube;
6. the photovoltaic power generation system comprises a third photovoltaic unit group, a second photovoltaic unit group, a first switch tube, a fifth photovoltaic unit group, an eighth photovoltaic unit group and a seventh switch tube.
When the second, fourth, sixth, and eighth switching tubes are turned on, the circuit mode of the photovoltaic sub-module based on the new architecture without the capacitor voltage equalizer is shown in fig. 7, and the mode includes six loops in total, which are:
1. the photovoltaic power generation system comprises a first photovoltaic unit group, a first switching tube, a fifth photovoltaic unit group, a sixth photovoltaic unit group and a fourth switching tube;
2. a third photovoltaic unit group, a fourth switching tube, a sixth photovoltaic unit group, a seventh photovoltaic unit group and a sixth switching tube;
3. a fourth photovoltaic unit group, a sixth switching tube, a seventh photovoltaic unit group, an eighth photovoltaic unit group and an eighth switching tube;
4. the photovoltaic power generation system comprises a third photovoltaic unit group, a second switch tube, a fifth photovoltaic unit group, a seventh photovoltaic unit group and a sixth switch tube;
5. the fourth photovoltaic unit group, the third photovoltaic unit group, the fourth switching tube, the sixth photovoltaic unit group, the eighth photovoltaic unit group and the eighth switching tube;
6. the photovoltaic power generation system comprises a fourth photovoltaic unit group, a third photovoltaic unit group, a second switch tube, a fifth photovoltaic unit group, an eighth photovoltaic unit group and an eighth switch tube.
When power mismatch is generated between any two photovoltaic unit groups due to illumination difference or other factors, a loop for directly transmitting energy between the two photovoltaic unit groups can be found.
In the photovoltaic sub-module with the new architecture based on the capacitor voltage equalizer of the embodiment, when each photovoltaic unit operates normally, the corresponding voltage is substantially equal, the number of each group of photovoltaic units is related to the voltage balance of the circuit, that is, the voltages of 12 loops in total in two circuit modes are balanced, and the current in the loops is determined by the small voltage difference between the units and the parasitic resistance in the loops.
The photovoltaic sub-module designed by the embodiment is a component of a photovoltaic module (i.e. a common photovoltaic cell panel in the market), i.e. a plurality of photovoltaic sub-modules are connected in a specific manner to obtain the photovoltaic module.
In one example, in order to verify the differential power processing effect between the photovoltaic units of the photovoltaic sub-modules with the new architecture in the embodiment, a Matlab/Simulink model is established. First of allLight intensity of the photovoltaic unit group is 500W/m2The light intensity of the second photovoltaic unit group to the eighth photovoltaic unit group is 800W/m2The obtained current simulation waveform of 8 cell groups is shown in fig. 8, where the abscissa represents time and the ordinate represents current in fig. 8. It can be seen that the output current of each group of units is substantially proportional to the respective light intensity, which illustrates that the structure of the photovoltaic sub-module with the new architecture shown in fig. 4 can overcome the adverse effect caused by power mismatch.
In summary, in this embodiment, starting from the photovoltaic unit level, only the switching tube and the photovoltaic unit are adopted to realize the new architecture photovoltaic sub-module integrated by the capacitor-less voltage equalizer, so that the energy acquisition rate of the photovoltaic system when the power between the photovoltaic units is mismatched is improved, a direct transmission channel of differential energy between the photovoltaic units with mismatched power is established, and the power generation efficiency of the photovoltaic system is greatly improved; the invention essentially belongs to a switch capacitor converter, and utilizes the parasitic diffusion capacitor of the photovoltaic unit to replace the capacitor in the traditional topology, thereby reducing the integration difficulty and cost of the photovoltaic sub-module.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
It should be noted that the terms "first \ second \ third" referred to in the embodiments of the present application merely distinguish similar objects, and do not represent a specific ordering for the objects, and it should be understood that "first \ second \ third" may exchange a specific order or sequence when allowed. It should be understood that "first \ second \ third" distinct objects may be interchanged under appropriate circumstances such that the embodiments of the application described herein may be implemented in an order other than those illustrated or described herein.
The terms "comprises" and "comprising," and any variations thereof, of the embodiments of the present application, are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, product, or device that comprises a list of steps or modules is not limited to the listed steps or modules but may alternatively include other steps or modules not listed or inherent to such process, method, product, or device.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (4)

1. A new framework photovoltaic sub-module based on a capacitor-free voltage equalizer is characterized by comprising a first photovoltaic unit, a second photovoltaic unit, a third photovoltaic unit, a fourth photovoltaic unit, a fifth photovoltaic unit, a sixth photovoltaic unit, a seventh photovoltaic unit, an eighth photovoltaic unit, a ninth photovoltaic unit, a tenth photovoltaic unit, an eleventh photovoltaic unit, a twelfth photovoltaic unit, a thirteenth photovoltaic unit, a fourteenth photovoltaic unit, a fifteenth photovoltaic unit, a sixteenth photovoltaic unit, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube, a sixth switch tube, a seventh switch tube and an eighth switch tube;
the negative electrode of the first photovoltaic unit is connected with the positive electrode of the second photovoltaic unit, the negative electrode of the third photovoltaic unit is connected with the positive electrode of the fourth photovoltaic unit, the negative electrode of the fifth photovoltaic unit is connected with the positive electrode of the sixth photovoltaic unit, the negative electrode of the seventh photovoltaic unit is connected with the positive electrode of the eighth photovoltaic unit, the negative electrode of the ninth photovoltaic unit is connected with the positive electrode of the tenth photovoltaic unit, the negative electrode of the tenth photovoltaic unit is connected with the positive electrode of the eleventh photovoltaic unit, the negative electrode of the sixteenth photovoltaic unit is connected with the positive electrode of the fifteenth photovoltaic unit, and the negative electrode of the fifteenth photovoltaic unit is connected with the positive electrode of the fourteenth photovoltaic unit; the negative electrode of the eleventh photovoltaic unit, the negative electrode of the twelfth photovoltaic unit, the positive electrode of the thirteenth photovoltaic unit and the positive electrode of the sixteenth photovoltaic unit are connected together; the source electrode of the first switching tube, the drain electrode of the second switching tube and the anode of the ninth photovoltaic unit are connected together; the source electrode of the third switching tube, the drain electrode of the fourth switching tube and the anode of the twelfth photovoltaic unit are connected together; the source electrode of the fifth switching tube, the drain electrode of the sixth switching tube and the negative electrode of the thirteenth photovoltaic unit are connected together; the source electrode of the seventh switching tube, the drain electrode of the eighth switching tube and the negative electrode of the fourteenth photovoltaic unit are connected together; the negative electrode of the second photovoltaic unit, the positive electrode of the third photovoltaic unit, the source electrode of the second switching tube and the drain electrode of the third switching tube are connected together; the negative electrode of the fourth photovoltaic unit, the positive electrode of the fifth photovoltaic unit, the source electrode of the fourth switching tube and the drain electrode of the fifth switching tube are connected together; and the negative electrode of the sixth photovoltaic unit, the positive electrode of the seventh photovoltaic unit, the source electrode of the sixth switching tube and the drain electrode of the seventh switching tube are connected together.
2. The capacitor-less equalizer-based new architecture photovoltaic sub-module of claim 1, comprising a first photovoltaic cell group, a second photovoltaic cell group, a third photovoltaic cell group, a fourth photovoltaic cell group, a fifth photovoltaic cell group, a sixth photovoltaic cell group, a seventh photovoltaic cell group, an eighth photovoltaic cell group, a first switch group, a second switch group, a third switch group, and a fourth switch group;
the first photovoltaic unit group comprises a first photovoltaic unit and a second photovoltaic unit; the second photovoltaic unit group comprises a third photovoltaic unit and a fourth photovoltaic unit; the third photovoltaic unit group comprises a fifth photovoltaic unit and a sixth photovoltaic unit; the fourth photovoltaic unit group comprises a seventh photovoltaic unit and an eighth photovoltaic unit; the fifth photovoltaic unit group comprises a ninth photovoltaic unit, a tenth photovoltaic unit and an eleventh photovoltaic unit; the sixth photovoltaic unit group comprises a twelfth photovoltaic unit; the seventh photovoltaic cell group comprises a thirteenth photovoltaic cell; the eighth photovoltaic unit group comprises a fourteenth photovoltaic unit, a fifteenth photovoltaic unit and a sixteenth photovoltaic unit; the first switch group comprises a first switch tube and a second switch tube; the second switch group comprises a third switch tube and a fourth switch tube; the third switch group comprises a fifth switch tube and a sixth switch tube, and the fourth switch group comprises a seventh switch tube and an eighth switch tube.
3. The capacitor-less voltage equalizer-based new-architecture photovoltaic sub-module as claimed in claim 1, wherein the positive electrode of the first photovoltaic cell and the drain electrode of the first switching tube are connected together and serve as the positive electrode of the whole new-architecture photovoltaic sub-module; and the negative electrode of the eighth photovoltaic unit and the source electrode of the eighth switching tube are connected together and are used as the negative electrode of the whole photovoltaic submodule with the new framework.
4. The new architecture photovoltaic sub-module based on the capacitor-less voltage equalizer according to claim 1, wherein the driving signals of the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube are all pulse width modulation signals with a duty ratio of 50%, and any two adjacent switch tubes are complementary.
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CN102832661A (en) * 2012-08-06 2012-12-19 东南大学 Novel dynamic voltage sharing device for serially connected super capacitor bank
CN103269174A (en) * 2012-12-10 2013-08-28 江西南昌供电公司 Single-phase photovoltaic grid-connected inverter with low common-mode voltage
US20130320767A1 (en) * 2012-05-30 2013-12-05 Delta Electronics, Inc. Photovoltaic power system with generation modules
CN106788366A (en) * 2016-11-17 2017-05-31 华中科技大学 A kind of voltage equalizing protection circuit for series IGBT

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102111080A (en) * 2011-02-24 2011-06-29 广州智光电气股份有限公司 Photovoltaic grid-connected inverter and control method
US20130320767A1 (en) * 2012-05-30 2013-12-05 Delta Electronics, Inc. Photovoltaic power system with generation modules
CN102832661A (en) * 2012-08-06 2012-12-19 东南大学 Novel dynamic voltage sharing device for serially connected super capacitor bank
CN103269174A (en) * 2012-12-10 2013-08-28 江西南昌供电公司 Single-phase photovoltaic grid-connected inverter with low common-mode voltage
CN106788366A (en) * 2016-11-17 2017-05-31 华中科技大学 A kind of voltage equalizing protection circuit for series IGBT

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