CN114142738B - Three-port photovoltaic energy storage type LLC resonant converter and light load control strategy - Google Patents
Three-port photovoltaic energy storage type LLC resonant converter and light load control strategy Download PDFInfo
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- CN114142738B CN114142738B CN202111502225.3A CN202111502225A CN114142738B CN 114142738 B CN114142738 B CN 114142738B CN 202111502225 A CN202111502225 A CN 202111502225A CN 114142738 B CN114142738 B CN 114142738B
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- light load
- energy storage
- control strategy
- switch tube
- llc resonant
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/3353—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter
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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
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
- H02J7/35—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering with light sensitive cells
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
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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
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention discloses a three-port photovoltaic energy storage type LLC resonant converter and a light load control strategy, wherein a pair of reverse switching tubes Q is added on the primary side of the topology of the traditional three-port photovoltaic energy storage type LLC resonant converter 5 、Q 6 The secondary side is added with a variable-mode switching tube Q 7 . Under the light load working condition, the control strategy of the intermittent mode is applied to the switching tube Q 7 And controlling the on-off of the device to realize the mode switching. By means of the mode, compared with a traditional three-port photovoltaic energy storage type LLC resonant converter, the topology provided by the invention can store redundant energy in the storage battery while meeting the load demand under the condition of sufficient illumination, so that the photovoltaic utilization rate is improved, meanwhile, the problem of overhigh frequency of the traditional topology under the light load working condition is solved by applying the light load control strategy, and the switching loss caused by overhigh switching frequency is reduced.
Description
Technical Field
The invention relates to the technical field of power electronic converters in photovoltaic power generation and storage battery energy storage, in particular to a three-port LLC resonant converter.
Background
The national energy conservation and emission reduction policy promotes the rapid development of new energy technology, and photovoltaic power generation is used as a clean energy source and is increasingly widely applied. However, the electric energy emitted by the photovoltaic power supply is greatly affected by temperature and illumination intensity, and needs to be matched with an energy storage system for use so as to ensure the output stability of the photovoltaic power supply. The LLC resonant converter is widely applied to the DC/DC converter because of high power density and high efficiency, and the three-port photovoltaic energy storage type LLC resonant converter can integrate a photovoltaic power supply, a storage battery and a load into one circuit and has the characteristics of high efficiency, high power density and the like.
In recent years, attention is paid to the problem of loss of the converter under the light load working condition at home and abroad. The LLC resonant converter has the problems of voltage gain distortion, overhigh switching frequency and the like in light load, and the common solution is to adopt Burst control. The basic principle of Burst control is to realize dynamic stabilization of output voltage in a fixed range by intermittently controlling on and off of a switching tube. However, burst control is typically applied to the input side switching tube, which can result in maximum power tracking of the photovoltaic power supply in the three-port photovoltaic energy storage LLC resonant converter being impractical.
Disclosure of Invention
The invention provides a three-port photovoltaic energy storage type LLC resonant converter and a light load control strategy, which are used for achieving the purposes of stabilizing the switching frequency of a switching tube under a light load working condition, improving the light load efficiency and improving the photovoltaic power utilization rate.
In order to achieve the above purpose, the technical scheme provided by the invention is as follows:
the three-port photovoltaic energy storage type LLC resonant converter specifically comprises: storage battery connection switch tube Q 1 、Q 2 The half-bridge structure is formed by resonant inductance L r Connect a pair of reverse connection switch tubes Q 5 、Q 6 Switch tube Q 5 、Q 6 And resonance capacitor C r Parallel connection; photovoltaic power supply connection switch tube Q 3 、Q 4 The half-bridge structure is formed by exciting inductance L m Connecting resonance capacitor C r The method comprises the steps of carrying out a first treatment on the surface of the The secondary side of the transformer passes through a diode D 1 、D 2 、D 3 、D 4 The rectifier bridge is connected with a mode switching tube Q 7 Through a filter capacitor C o A load is connected.
The switching tube is operated by the controller according to the following control strategy:
when the three-port photovoltaic energy storage type LLC resonant converter operates under a light load working condition, the controller outputs pulses to control the switching tube Q 1 、Q 2 And the photovoltaic power supply is alternately conducted at a fixed frequency, and the duty ratio is determined by the maximum power tracking control of the photovoltaic power supply. The controller outputs pulse to control the switch tube Q 3 Conducting, Q 4 Switch-off and reverse-connection switch tube Q 5 、Q 6 And the photovoltaic power supply is conducted to continuously charge the storage battery to direct current through the resonant circuit.
The switch tube Q 1 、Q 2 Is determined according to circuit parameters.
The switch tube Q 7 The control strategy of (1) is as follows, when the output voltage V o Higher than a preset maximum voltage V omax At the time, switch tube Q 7 The whole secondary side circuit is disconnected, the photovoltaic power supply stores energy into the storage battery through the primary side circuit, and the output voltage is reduced; when outputting voltage V o Below a preset minimum voltage V omin At the time, switch tube Q 7 On, the primary side transfers energy to the load through the transformer, the output voltage rises, and so on.
The switch tube Q 1 、Q 2 、Q 3 、Q 4 、Q 5 、Q 6 、Q 7 Are MOSFETs.
The beneficial effects of the invention are as follows:
(1) According to the invention, the reverse switching tube connected in parallel with the two ends of the resonant capacitor is adopted, and is conducted to short-circuit the resonant capacitor when the photovoltaic power supply charges the storage battery, so that the problem that the traditional photovoltaic energy storage three-port LLC resonant circuit cannot realize direct current charging of the photovoltaic power supply to the storage battery due to the fact that the resonant capacitor is contained in the resonant circuit is solved.
(2) According to the invention, the control principle of intermittent control is applied to the secondary side switching tube when the circuit is in light load, and the secondary side switching tube is controlled to intermittently switch on and off to perform modal switching on the circuit, so that the problem that the switching frequency of the traditional photovoltaic energy storage three-port LLC resonant circuit is too high under the light load working condition is solved, and the light load efficiency of the circuit is improved.
Drawings
Fig. 1 is a circuit structure diagram of a three-port photovoltaic energy storage type LLC resonant converter provided by the invention.
Fig. 2 is a schematic diagram of a control strategy of the converter according to the present invention when the converter is operated under a light load condition.
Fig. 3 (a) and (b) are schematic diagrams of the working modes of the circuit when the converter provided by the invention operates under the light load working condition.
Fig. 4 is a simulated waveform diagram of the converter provided by the invention when operating under a light load condition.
Meaning of symbols in the drawings: v (V) battery An output/input source for the battery; v (V) pv The photovoltaic power supply is an output source of a photovoltaic power supply; q (Q) 1 、Q 2 、Q 3 、Q 4 、Q 5 、Q 6 、Q 7 Is a MOSFET switch tube; c (C) 1 、C 2 Is an input capacitance; c (C) r Is a resonance capacitor; l (L) r Is a resonant inductance; l (L) m The excitation inductance is adopted; d (D) 1 、D 2 、D 3 、D 4 Is a freewheeling diode; c (C) o Is an output capacitance; v (V) omax Is the maximum value of preset output voltage; v (V) omin Is a preset minimum value of the output voltage.
Detailed Description
The present invention is described in detail below with reference to the drawings so that advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making clear and defining the scope of the present invention.
Aiming at the problem that a photovoltaic power supply cannot charge a storage battery through a resonant circuit when illumination is sufficient in a traditional three-port photovoltaic energy storage type LLC resonant converter, as shown in figure 1, the invention comprises a pair of reverse connection switching tubes Q 5 、Q 6 Resonant capacitor C connected in parallel to three-port photovoltaic energy storage type LLC resonant converter r Is provided. When the photovoltaic power supply charges the storage battery directly, the reverse connection switch tube Q 5 、Q 6 Conducting will resonate capacitor C r Short circuit, photovoltaic power supply passes through reverse connection switch tube Q in resonant circuit 5 、Q 6 And resonant inductance L r Direct current charging of the accumulator, thereby avoiding resonance capacitor C r Is used for blocking the straight line.
Aiming at the problems of voltage gain imbalance, over-high switching frequency, low circuit efficiency and the like of the traditional three-port photovoltaic energy storage type LLC resonant converter under the light load working condition, as shown in figure 1, the invention provides a mode switching switch tube Q 7 And the three-port photovoltaic energy storage type LLC resonant converter is connected into a secondary side loop of the three-port photovoltaic energy storage type LLC resonant converter. By controlling the switching tube Q 7 The on-off of the output voltage is realized, so that the output voltage is stabilized near the rated output voltage.
The light load control strategy of the three-port photovoltaic energy storage type LLC resonant converter is specifically as follows: first, the controller outputs pulse to control the switch tube Q 1 、Q 2 Alternately conducting and switching tube Q with fixed frequency 3 Conduction and switching tube Q 4 Switch-off and reverse-connection switch tube Q 5 、Q 6 Conducting. Then selecting a preset maximum value V of the output voltage according to the ripple requirement of the output voltage omax And a preset minimum value V of output voltage omin To the secondary side switch tube Q 7 Using intermittent control to output voltage V o Controlled at V omin And V is equal to omax Between them.
As shown in fig. 2, at t 0 Time to time switching tube Q 7 After intermittent control, switch tube Q 7 On, the circuit is in mode 1 operation, as shown in fig. 3 (a), in which the photovoltaic power supply supplies energy to the load while storing excess energy in the battery via the resonant tank, outputting a voltage V o Ascending; when t 1 Output voltage V at moment o Rising to a preset output voltage maximum value V omax At the time, switch tube Q 7 The secondary side is disconnected by the disconnection, the circuit is in the running state of the mode 2, as shown in the figure 3 (b), the photovoltaic power supply only charges the storage battery, and the voltage V is output o Descending; when t 2 The output voltage drops to the minimum value V of the preset output voltage at the moment omin At the time, switch tube Q 7 And conducting again, and repeating the steps.
Simulation analysis is carried out on the three-port photovoltaic energy storage LLC resonant converter circuit under the light load working condition by utilizing MATLAB/Simulink simulation software, and rated output voltage V is set o Setting a preset maximum value V of output voltage to 12V omax Setting the minimum value V of the preset output voltage to be 12.2V omin 11.8V. As shown in FIG. 4, the upper graph shows the waveform of the output voltage, and the lower graph shows the switching transistor Q 7 And driving the waveform, and ensuring the feasibility of the light load control strategy by conforming the obtained simulation waveform diagram to the proposed light load control strategy.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.
Claims (4)
1. The utility model provides a three port photovoltaic-energy storage formula LLC resonant converter topology for realize the power flow between photovoltaic power supply, battery, the load, its characterized in that: storage battery connection switch tube Q 1 、Q 2 The half-bridge structure is formed by resonant inductance L r Connect a pair of reverse connection switch tubes Q 5 、Q 6 Switch tube Q 5 、Q 6 Series-connected and resonant capacitor C r Parallel connection; photovoltaic power supply connection switch tube Q 3 、Q 4 The half-bridge structure is formed by exciting inductance L m Connecting resonance capacitor C r The method comprises the steps of carrying out a first treatment on the surface of the The secondary side of the transformer passes through a diode D 1 、D 2 、D 3 、D 4 The rectifier bridge is connected with a mode switching tube Q 7 Through a filter capacitor C o A load is connected.
2. A light load control strategy applicable to the three port photovoltaic-energy storage LLC resonant converter topology of claim 1, wherein: when the circuit operates under the light load working condition, the switch tube Q 1 、Q 2 Alternately conducting at a fixed frequency, switching tube Q 3 Conducting, Q 4 Turn-off, reverse connection switch tube Q 5 、Q 6 Conducting; when outputting voltage V o Higher than a preset maximum voltage V omax At the time, switch tube Q 7 The whole secondary side circuit is disconnected, the photovoltaic power supply stores energy into the storage battery through the primary side circuit, and the output voltage is reduced; when outputting voltage V o Below a preset minimum voltage V omin At the time, switch tube Q 7 On, the primary side transfers energy to the load through the transformer, the output voltage rises, and so on.
3. According to claim 2The light load control strategy of (1) is characterized in that: the switching tube Q which operates at fixed frequency 1 、Q 2 Is given according to specific design parameters of the circuit.
4. The light load control strategy of claim 2, wherein: the preset highest voltage V omax Preset minimum voltage V omin According to the output voltage ripple requirement in practical application.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111502225.3A CN114142738B (en) | 2021-12-09 | 2021-12-09 | Three-port photovoltaic energy storage type LLC resonant converter and light load control strategy |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111502225.3A CN114142738B (en) | 2021-12-09 | 2021-12-09 | Three-port photovoltaic energy storage type LLC resonant converter and light load control strategy |
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| Publication Number | Publication Date |
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| CN114142738A CN114142738A (en) | 2022-03-04 |
| CN114142738B true CN114142738B (en) | 2023-10-03 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103944396A (en) * | 2014-04-11 | 2014-07-23 | 燕山大学 | LLC resonance type three-port DC-DC converter and control method thereof |
| CN111654191A (en) * | 2020-04-02 | 2020-09-11 | 天津工业大学 | LLC resonant three-port DC-DC converter structure |
| CN113037092A (en) * | 2021-03-15 | 2021-06-25 | 天津理工大学 | Three-port bidirectional DC-DC converter and control method thereof |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU2013370446A1 (en) * | 2012-12-30 | 2015-05-07 | Enphase Energy, Inc. | Three port converter with dual independent maximum power point tracking and dual operating modes |
| US9484821B2 (en) * | 2013-11-04 | 2016-11-01 | Futurewei Technologies, Inc. | Adjustable resonant apparatus for power converters |
-
2021
- 2021-12-09 CN CN202111502225.3A patent/CN114142738B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103944396A (en) * | 2014-04-11 | 2014-07-23 | 燕山大学 | LLC resonance type three-port DC-DC converter and control method thereof |
| CN111654191A (en) * | 2020-04-02 | 2020-09-11 | 天津工业大学 | LLC resonant three-port DC-DC converter structure |
| CN113037092A (en) * | 2021-03-15 | 2021-06-25 | 天津理工大学 | Three-port bidirectional DC-DC converter and control method thereof |
Non-Patent Citations (3)
| Title |
|---|
| "Variable Frequency-duty cycle modulation technique for light load efficiency improvement of LLC resonant converter for wide input voltage range in PV applications";Abhishek Awasthi等;《2019 CPERE会议》;全文 * |
| 一种隔离型三端口双向LCLC多谐振直流变换器;李微;王议锋;韩富强;陈博;;电工技术学报(第14期);全文 * |
| 基于多模态切换的宽电压增益LLC谐振变换器控制策略;冯兴田;邵康;崔晓;马文忠;王玉彬;;电工技术学报(第20期);全文 * |
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