CN111555260B - Photovoltaic submodule based on capacitor-free voltage equalizer - Google Patents
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- 238000009792 diffusion process Methods 0.000 description 5
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- 238000009434 installation Methods 0.000 description 3
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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
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- 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
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- 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
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- 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
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Abstract
The invention discloses a novel-architecture photovoltaic sub-module 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 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 with each other in a specific mode, so that a direct channel for differential energy transmission is provided, gradual transmission of differential energy is avoided, the energy acquisition rate of a photovoltaic system in the case of power mismatch among the photovoltaic units is improved, and the power generation efficiency of the photovoltaic system is greatly improved.
Description
Technical Field
The invention relates to the technical field of power electronic converters and control, in particular to a photovoltaic sub-module based on a capacitance-free voltage equalizer.
Background
A photovoltaic module is a device for converting solar energy into electric energy, and is used in applications where solar energy is used to generate electricity, such as a solar power plant, a solar street lamp, and the like. At present, the main current use form of the photovoltaic is centralized power generation, namely photovoltaic modules (PV modules) are connected in series and in parallel to obtain a photovoltaic array (PV array), and after high enough output voltage and current are ensured, a high-power centralized grid-connected inverter is used for carrying out Maximum Power Point Tracking (MPPT) and grid-connected control. However, the method has obvious disadvantages that the input voltage with extremely wide variation range requires a device with high withstand voltage and high on-resistance, and the DC voltage utilization rate of the inverter at the later stage is low, so that the efficiency of the inverter is low; in addition, due to the influences of factors such as local shadows, deviation of installation angles of photovoltaic cell modules, dust, electric parameter differences and the like, in the photovoltaic array, voltage and current at the Maximum Power Point (MPP) of each cell module output cannot be consistent, so that the output power of the photovoltaic array is limited to the photovoltaic module with the minimum power, the phenomenon is called power mismatch, the loss of power is more than 30% when serious, hot spots are generated on the photovoltaic module after long-term operation, and the module is burnt.
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, wherein the three schemes can ensure that the photovoltaic module (with common power of about 200W) can realize MPP operation to a certain extent, but the problem of low energy acquisition rate caused by power mismatch among photovoltaic units is easy.
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 the photovoltaic sub-module based on the capacitance-free voltage equalizer, so that the connection mode of the traditional photovoltaic sub-module is changed, the energy acquisition rate of a photovoltaic system when the power of the photovoltaic units is mismatched is improved, a direct differential energy transmission channel between the photovoltaic units with the power mismatched is established, and the power generation efficiency of the photovoltaic system is greatly improved; and the parasitic diffusion capacitance of the photovoltaic unit is utilized to replace the capacitance in the traditional topology, so that the number of adopted devices is reduced, and the integration difficulty of the photovoltaic sub-module is reduced.
A 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 and 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 cathode of the first photovoltaic unit is connected with the anode of the second 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 positive electrode 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 positive electrode 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 cathode of the second photovoltaic unit, the anode 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 cathode of the fourth photovoltaic unit, the anode 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 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 one embodiment, the photovoltaic sub-module based on the capacitor-less voltage equalizer includes a first photovoltaic unit group, a second photovoltaic unit group, a third photovoltaic unit group, a fourth photovoltaic unit group, a fifth photovoltaic unit group, a sixth photovoltaic unit group, a seventh photovoltaic unit group, an eighth photovoltaic unit group, a first switch group, a second switch group, a third switch group, and a fourth switch group;
wherein the first photovoltaic cell group comprises a first photovoltaic cell and a second photovoltaic cell; 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 cell group includes a twelfth photovoltaic cell; the seventh photovoltaic cell group includes thirteenth photovoltaic cells; the eighth photovoltaic cell group includes a fourteenth photovoltaic cell, a fifteenth photovoltaic cell, and a sixteenth photovoltaic cell; 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 anode of the first photovoltaic unit and the drain of the first switching tube are connected together and serve as the anode of the whole new-architecture photovoltaic sub-module; the cathode of the eighth photovoltaic unit and the source electrode of the eighth switching tube are connected together and serve as the cathode of the whole photovoltaic sub-module with the new framework.
In one embodiment, the driving signals of the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the fifth switching tube, the sixth switching tube, the seventh switching tube and the eighth switching tube are pulse width modulation signals with 50 percent of duty ratio, and the driving signals of any two adjacent switching tubes are complementary
The photovoltaic sub-module based on the capacitor-free voltage equalizer is characterized in that 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 positive electrode 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 positive electrode 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 cathode of the second photovoltaic unit, the anode 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 cathode of the fourth photovoltaic unit, the anode 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 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, so that when power of each photovoltaic unit is lost due to different local shadows, aging degrees, installation angles and the like, the novel framework photovoltaic submodule provides a direct channel for differential energy transmission, step-by-step transmission of differential energy is avoided, the energy acquisition rate of the photovoltaic system is improved when power among the photovoltaic units is lost, 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 the internal wiring of a conventional photovoltaic module;
FIG. 3 is a photovoltaic unit equivalent circuit diagram;
FIG. 4 is a schematic diagram of a block structure of light Fu Zimo based on a capacitive-less pressure equalizer according to one embodiment;
FIG. 5 is a simulation model diagram of a photovoltaic sub-module based on a capacitance-free voltage equalizer of one embodiment;
FIG. 6 is a simulated waveform diagram of a photovoltaic sub-module based on a capacitance-free voltage equalizer of one embodiment;
FIG. 7 is a schematic diagram of the circuit mode of a photovoltaic sub-module based on a capacitance-free voltage equalizer of one embodiment;
fig. 8 is a current simulation waveform diagram of an embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only 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 may be included in at least one embodiment of the present application. The appearances of such phrases 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. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.
The front view of the most common 72 photovoltaic cells (PV cells) and the photovoltaic modules (PV modules) with open circuit voltage of about 36V in the market is shown in fig. 1, the schematic view of the internal wiring is shown in fig. 2, the open circuit voltage of each photovoltaic cell is about 0.6V, each 24 cells form a photovoltaic sub-module (PV sub-module), and the bypass diode prevents the influence on other sub-modules when the power is lost.
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, wherein the three schemes can ensure that the photovoltaic module (common power of about 200W) realizes MPP operation, but the following problems also exist:
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 module power output characteristic to contain a plurality of local peaks, so that the difficulty of an 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 submodules can be solved, in order to obtain voltage matched with a later-stage converter or a load, the output voltage is required to be stabilized through a concentrated DC/DC converter, so that the scheme still has the defects of complex structure and low efficiency;
3. from the minimum photovoltaic unit level, all three schemes will result in loss of energy output when power is lost.
At present, all three schemes have a certain degree of defects, and the photovoltaic sub-modules must be re-integrated from the photovoltaic unit level, so that new photovoltaic modules are integrated. However, the current new architecture technology based on the photovoltaic unit is in a starting stage, passive elements such as capacitors and inductors are needed in the integration process, and the integration difficulty is increased. The equivalent model of the photovoltaic unit is perfected in recent years, and the equivalent circuit is shown in figure 3, wherein C d The equivalent capacitance of the combination of the diffusion capacitance and the depletion layer capacitance of the photovoltaic unit is represented, and the diffusion capacitance occupies a main part and the depletion layer capacitance is negligible near the maximum power point of the photovoltaic unit. Related 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 low energy acquisition rate caused by power mismatch between photovoltaic units in a photovoltaic system and facilitate integration of the photovoltaic units, in one embodiment, a photovoltaic sub-module based on a capacitance-free voltage equalizer is constructed from a photovoltaic unit level, as shown in fig. 4, and the meaning of symbol names in fig. 4 includes: PV+ represents the output anode of the photovoltaic module; PV-represents the output cathode of the photovoltaic module; i sc Representing the equivalent current source of the photovoltaic unit; d (D) d Representing a photovoltaic cell equivalent diode; c (C) d Representing the diffusion capacitance of the photovoltaic cell; r is R p Representing the equivalent parallel resistance of the photovoltaic unit; r is R s Representing the equivalent series resistance of the photovoltaic unit; pvs+ represents the new architecture photovoltaic submodule anode; PVS-represents the negative pole of the photovoltaic submodule with the new architecture; PV (photovoltaic) system C1 -PV C16 Representing the first to sixteenth photovoltaic units; s is S C1 -S C8 Representing the first switching tube to the eighth switching tube; u (u) SC1 -u SC8 Representing corresponding driving signals of the first switching tube to the eighth switching tube; i.e PVC1 -i PVC8 Representing the current flowing through the first to eighth photovoltaic cell groups; i PVC1 -I PVC8 Indicating flow through the first photovoltaic cell group through eighthCurrent average of photovoltaic cell group. The structure utilizes the equivalent capacitance of the photovoltaic unit to store energy, eliminates passive elements in the structure, and realizes the transmission of differential energy through the capacitance-free voltage equalizer when the power of the photovoltaic unit is lost, thereby ensuring that the photovoltaic unit works at the respective maximum power point.
The novel-architecture photovoltaic sub-module 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 and 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 cathode of the first photovoltaic unit is connected with the anode of the second 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 positive electrode 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 positive electrode 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 cathode of the second photovoltaic unit, the anode 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 cathode of the fourth photovoltaic unit, the anode 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 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 novel-architecture photovoltaic sub-module based on the capacitor-free voltage equalizer is characterized in that 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 positive electrode 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 positive electrode 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 cathode of the second photovoltaic unit, the anode 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 cathode of the fourth photovoltaic unit, the anode 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 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, so that when power of each photovoltaic unit is lost due to different local shadows, aging degrees, installation angles and the like, the novel framework photovoltaic submodule provides a direct channel for differential energy transmission, step-by-step transmission of differential energy is avoided, the energy acquisition rate of the photovoltaic system is improved when power among the photovoltaic units is lost, and the power generation efficiency of the photovoltaic system is greatly improved.
In one embodiment, a novel architecture photovoltaic sub-module based on a capacitance-free voltage equalizer comprises a first photovoltaic unit group, a second photovoltaic unit group, a third photovoltaic unit group, a fourth photovoltaic unit group, a fifth photovoltaic unit group, a sixth photovoltaic unit group, a seventh photovoltaic unit group, an eighth photovoltaic unit group, a first switch group, a second switch group, a third switch group and a fourth switch group;
wherein the first photovoltaic cell group comprises a first photovoltaic cell and a second photovoltaic cell; 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 cell group includes a twelfth photovoltaic cell; the seventh photovoltaic cell group includes thirteenth photovoltaic cells; the eighth photovoltaic cell group includes a fourteenth photovoltaic cell, a fifteenth photovoltaic cell, and a sixteenth photovoltaic cell; 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 novel-architecture photovoltaic submodule of the capacitor-free 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; wherein 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 cell group includes a twelfth photovoltaic cell; the seventh photovoltaic cell group includes thirteenth photovoltaic cells; 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 anode of the first photovoltaic unit and the drain of the first switching tube are connected together and serve as the anode of the whole new-architecture photovoltaic sub-module; the cathode of the eighth photovoltaic unit and the source electrode of the eighth switching tube are connected together and serve as the cathode of the whole photovoltaic sub-module with the new framework.
In one embodiment, the driving signals of the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the fifth switching tube, the sixth switching tube, the seventh switching tube and the eighth switching tube are pulse width modulation signals with 50% duty ratio, and the driving signals of any two adjacent switching tubes are complementary.
In the embodiment, pulse width modulation signals with 50% duty ratio 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 as driving signals, so that accurate control of a photovoltaic sub-module with a new architecture based on a capacitor-free voltage equalizer can be realized, and corresponding control process is effectively simplified.
Specifically, in the control method of the photovoltaic sub-module with the new architecture based on the capacitor-free voltage equalizer, the driving signal of each switching tube in the eight switching tubes is a PWM signal with the duty ratio of 50%, and the driving signals of any two adjacent switching tubes are complementary, and the waveforms of the driving signals are shown in fig. 5. When the first, third, fifth and seventh switching tubes are turned on, the circuit mode of the photovoltaic sub-module with the new architecture based on the capacitor-free voltage equalizer is shown in fig. 6, and the circuit mode comprises six loops, which are respectively:
1. the first photovoltaic unit group, the first switching tube, the fifth photovoltaic unit group, the sixth photovoltaic unit group and the third switching tube;
2. the second photovoltaic unit group, the third switching tube, the sixth photovoltaic unit group, the seventh photovoltaic unit group and the fifth switching tube;
3. the third photovoltaic unit group, the fifth switching tube, the seventh photovoltaic unit group, the eighth photovoltaic unit group and the seventh switching tube;
4. the second photovoltaic unit group, the first switching tube, the fifth photovoltaic unit group, the seventh photovoltaic unit group and the fifth switching tube;
5. the third photovoltaic unit group, the second photovoltaic unit group, the third switching tube, the sixth photovoltaic unit group, the eighth photovoltaic unit group and the seventh switching tube;
6. the third photovoltaic unit group, the second photovoltaic unit group, the first switching tube, the fifth photovoltaic unit group, the eighth photovoltaic unit group and the seventh switching tube.
When the second, fourth, sixth and eighth switching tubes are turned on, the circuit mode of the photovoltaic sub-module with the new architecture based on the capacitor-free voltage equalizer is shown in fig. 7, and the mode includes six loops in total, which are respectively:
1. the second photovoltaic unit group, the second switching tube, the fifth photovoltaic unit group, the sixth photovoltaic unit group and the fourth switching tube;
2. the third photovoltaic unit group, the fourth switching tube, the sixth photovoltaic unit group, the seventh photovoltaic unit group and the sixth switching tube;
3. the fourth photovoltaic unit group, the sixth switching tube, the seventh photovoltaic unit group, the eighth photovoltaic unit group and the eighth switching tube;
4. the third photovoltaic unit group, the second switching tube, the fifth photovoltaic unit group, the seventh photovoltaic unit group and the sixth switching tube;
5. fourth photovoltaic unit group, third photovoltaic unit group, fourth switching tube, sixth photovoltaic unit group, eighth photovoltaic unit group and eighth switching tube;
6. the fourth photovoltaic unit group, the third photovoltaic unit group, the second switching tube, the fifth photovoltaic unit group, the eighth photovoltaic unit group and the eighth switching tube.
It can be seen that when power mismatch occurs between any two photovoltaic unit groups due to illumination differences or other factors, a loop for direct energy transmission between the two photovoltaic unit groups can always be found.
In the new-architecture photovoltaic sub-module based on the capacitor voltage equalizer of the embodiment, during normal operation, the corresponding voltage of each photovoltaic unit is basically equal, the number of photovoltaic unit configurations of each group 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 tiny voltage difference between the units and the parasitic resistance in the loops.
The photovoltaic sub-module designed in this embodiment is a component of a photovoltaic module (i.e. a photovoltaic panel commonly used in the market), that is, a plurality of photovoltaic sub-modules are connected in a specific manner, so as to obtain the photovoltaic module.
In one example, to verify the differential power handling effect between photovoltaic cells of the photovoltaic sub-modules of the new architecture in this embodiment, a Matlab/Simulink model was established. The light intensity of the first photovoltaic unit group is 500W/m 2 The light intensity of the second photovoltaic unit group to the eighth photovoltaic unit group is 800W/m 2 The current simulation waveforms of the obtained 8 cell groups are shown in fig. 8, and in fig. 8, the abscissa indicates time and the ordinate indicates current. It can be seen that the output current of each group of cells is substantially proportional to the respective light intensity, illustrating that the structure of the new architecture photovoltaic sub-module shown in fig. 4 can overcome the adverse effects of power mismatch.
In summary, according to the embodiment, starting from the photovoltaic unit level, the novel architecture photovoltaic sub-module integrated by the capacitor-free voltage equalizer is realized by only adopting the switching tube and the photovoltaic units, so that the energy acquisition rate of the photovoltaic system is improved when the power between the photovoltaic units is mismatched, a direct differential energy transmission channel between the photovoltaic units with the power mismatch is established, and the power generation efficiency of the photovoltaic system is greatly improved; the invention essentially belongs to a switch capacitance converter, utilizes parasitic diffusion capacitance of a photovoltaic unit to replace capacitance in traditional topology, and reduces integration difficulty and cost of a photovoltaic sub-module.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
It should be noted that, the term "first\second\third" in the embodiments of the present application is merely to distinguish similar objects, and does not represent a specific order for the objects, and it is understood that "first\second\third" may interchange a specific order or sequence where allowed. It is to be understood that the "first\second\third" distinguishing objects may be interchanged where appropriate to enable embodiments of the present application described herein to be implemented in sequences other than those illustrated or described herein.
The terms "comprising" and "having" and any variations thereof, in embodiments of the present application, are intended to cover a non-exclusive inclusion. For example, a process, method, apparatus, article, or device that comprises a list of steps or modules is not limited to the particular steps or modules listed and may optionally include additional steps or modules not listed or inherent to such process, method, article, or device.
The above examples merely represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.
Claims (2)
1. The photovoltaic sub-module based on the 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 and 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 cathode of the first photovoltaic unit is connected with the anode of the second 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 positive electrode 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 positive electrode 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 cathode of the second photovoltaic unit, the anode 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 cathode of the fourth photovoltaic unit, the anode 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 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 anode of the first photovoltaic unit and the drain electrode of the first switching tube are connected together and serve as the anode of the whole photovoltaic sub-module with the new architecture; the cathode of the eighth photovoltaic unit and the source electrode of the eighth switching tube are connected together and serve as the cathode of the whole photovoltaic sub-module with the new framework.
2. The capacitor-less voltage equalizer-based photovoltaic sub-module according to claim 1, wherein the driving signals of the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the fifth switching tube, the sixth switching tube, the seventh switching tube and the eighth switching tube are pulse width modulation signals with a duty cycle of 50%, and any adjacent two switching tube driving signals are complementary.
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| 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 |
| 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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| TW201349731A (en) * | 2012-05-30 | 2013-12-01 | Delta Electronics Inc | Photovoltaic power system with generation modules and method of controlling output power thereof |
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| 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 |
| 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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