CN114142738A - 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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- CN114142738A CN114142738A CN202111502225.3A CN202111502225A CN114142738A CN 114142738 A CN114142738 A CN 114142738A CN 202111502225 A CN202111502225 A CN 202111502225A CN 114142738 A CN114142738 A CN 114142738A
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- light
- load
- llc resonant
- control strategy
- resonant converter
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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
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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
- 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
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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
Abstract
The invention discloses a three-port photovoltaic energy storage LLC resonant converter and a light-load control strategy5、Q6The secondary side is added with a variable mode switching tube Q7. Under the light load working condition, the control strategy of the intermittent mode is applied to the switching tube Q7And controlling the on-off of the switch to realize mode switching. Through the mode, compared with the traditional three-port photovoltaic energy storage LLC resonant converter, the topology provided by the invention can meet the load requirement under the condition of sufficient illumination, and simultaneously, redundant energy is stored in the storage battery, 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 problem of overhigh frequency of the traditional topology under the light-load working condition is reducedSwitching losses due to too high a switching frequency.
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-saving and emission-reducing policy promotes the rapid development of new energy technology, and the photovoltaic power generation is more and more widely applied as clean energy. However, the electric energy generated by the photovoltaic power supply is greatly influenced by the temperature and the illumination intensity, and needs to be matched with an energy storage system to ensure the output stability. The LLC resonant converter is widely applied to the DC/DC converter due to 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 in one circuit and has the characteristics of high efficiency, high power density and the like.
In recent years, the problem of loss of the converter under a light load working condition is concerned at home and abroad. The problems of voltage gain distortion, overhigh switching frequency and the like can occur when the LLC resonant converter is in light load, and the conventional solution is to adopt Burst control. Burst control is also called intermittent control, and the basic principle of Burst control is that the output voltage is dynamically stabilized in a fixed range by intermittently controlling the on and off of a switching tube. However, Burst control is usually applied to the input switching tube, and this may cause that the maximum power tracking of the photovoltaic power supply in the three-port photovoltaic energy storage type LLC resonant converter cannot be realized.
Disclosure of Invention
The invention provides a three-port photovoltaic energy storage LLC resonant converter and a light load control strategy, and aims to achieve the purposes of stabilizing the switching frequency of a switching tube under the light load working condition, improving the light load efficiency and improving the utilization rate of a photovoltaic power supply.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
the three-port photovoltaic energy storage type LLC resonant converter specifically comprises: accumulator connecting switch tube Q1、Q2Constructed in a half-bridge configuration via a resonant inductor LrConnecting a pair of reverse switch tubes Q5、Q6Switching tube Q5、Q6And a resonance capacitor CrParallel connection; photovoltaic power supply connection switch tube Q3、Q4Constructed in a half-bridge configuration via an excitation inductance LmConnecting resonant capacitor Cr(ii) a The secondary side of the transformer passes through a diode D1、D2、D3、D4The formed rectifier bridge is connected with a mode switching tube Q7Through a filter capacitor CoA load is connected.
The switching tube is operated by the controller according to the following control strategy:
when the three-port photovoltaic energy storage LLC resonant converter operates under a light-load working condition, the controller outputs pulsesControl switch tube Q1、Q2And the photovoltaic power supply is alternately conducted at a fixed frequency, and the duty ratio of the photovoltaic power supply is determined by the maximum power tracking control of the photovoltaic power supply. The controller outputs pulse to control the switch tube Q3Conducting, Q4Turn-off and reverse connection switch tube Q5、Q6And the photovoltaic power supply is conducted to continuously carry out direct current charging on the storage battery through the resonant circuit.
The switch tube Q1、Q2The fixed turn-on frequency of (c) is determined based on circuit parameters.
The switch tube Q7The control strategy of (1) is as follows, when the output voltage V isoHigher than a predetermined maximum voltage VomaxTime, switch tube Q7The whole secondary side circuit is disconnected after the circuit is turned off, the photovoltaic power supply stores energy into the storage battery through the primary side loop, and the output voltage is reduced; when the output voltage V isoBelow a predetermined minimum voltage VominTime, switch tube Q7And (4) conducting, transmitting energy to the load through the transformer on the primary side, and increasing the output voltage repeatedly.
The switch tube Q1、Q2、Q3、Q4、Q5、Q6、Q7Are both MOSFETs.
The invention has the beneficial effects that:
(1) according to the photovoltaic energy storage three-port LLC resonant circuit, the reverse connection switch tubes are connected in parallel at two ends of the resonant capacitor, when the photovoltaic power supply charges the storage battery, the reverse connection switch tubes are conducted to short the resonant capacitor, and the problem that the photovoltaic power supply cannot charge the storage battery to direct current due to the fact that the resonant capacitor is contained in a resonant circuit of the traditional photovoltaic energy storage three-port LLC resonant circuit is solved.
(2) According to the invention, the control principle of intermittent control is applied to the secondary switch tube when the circuit is in light load, and the secondary switch tube is controlled to be intermittently switched on and off to perform modal switching on the circuit, so that the problem of overhigh switching frequency of the traditional photovoltaic energy storage three-port LLC resonant circuit in 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 present invention.
FIG. 2 is a schematic diagram of a control strategy for the converter of the present invention operating under light load conditions.
Fig. 3(a) and (b) are circuit operation mode diagrams of the converter provided by the invention when the converter operates under a light load working condition.
FIG. 4 is a waveform diagram of a simulation of the converter of the present invention operating under light load conditions.
The symbols in the drawings mean: vbatteryIs a storage battery output/input source; vpvIs a photovoltaic power output source; q1、Q2、Q3、Q4、Q5、Q6、Q7Is a MOSFET switch tube; c1、C2Is an input capacitance; crIs a resonant capacitor; l isrIs a resonant inductor; l ismIs an excitation inductor; d1、D2、D3、D4Is a freewheeling diode; coIs an output capacitor; vomaxIs a preset maximum value of the output voltage; vominIs a preset minimum value of the output voltage.
Detailed Description
The present invention is described in detail below with reference to the attached drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby clearly defining the protection scope of the present invention.
Aiming at the problem that a photovoltaic power supply cannot charge a storage battery through a resonant circuit when the traditional three-port photovoltaic energy storage type LLC resonant converter is sufficiently illuminated, as shown in figure 1, the invention connects a pair of reverse switching tubes Q5、Q6Resonant capacitor C connected in parallel in three-port photovoltaic energy storage type LLC resonant converterrAt both ends of the same. When the photovoltaic power supply charges the storage battery with direct current, the reverse connection switch tube Q5、Q6Conducting the resonant capacitor CrShort circuit, photovoltaic power supply passing through reverse switch tube Q in resonant circuit5、Q6And a resonant inductor LrCharging the accumulator with DC current, thereby avoiding the resonance capacitor CrThe blocking effect of (1).
Photovoltaic energy storage type LLC harmonic for traditional three portsThe converter has the problems of voltage gain imbalance, overhigh switching frequency, low circuit efficiency and the like under the light-load working condition, as shown in figure 1, the invention switches a mode switching tube Q7And the three-port photovoltaic energy storage type LLC resonant converter secondary side loop is accessed. By controlling the switching tube Q7The on-off of the voltage regulator realizes the rise and fall of the output voltage, thereby stabilizing the output voltage near the rated output voltage.
The light-load control strategy of the three-port photovoltaic energy storage type LLC resonant converter is as follows: firstly, the switch tube Q is controlled by the output pulse of the controller1、Q2Switching tube Q alternatively conducted and switched at fixed frequency3Conducting and switching tube Q4Turn-off and reverse connection switch tube Q5、Q6And conducting. Then selecting a preset maximum value V of the output voltage according to the ripple requirement of the output voltageomaxAnd a preset minimum value V of the output voltageominTo the secondary side switch tube Q7Using intermittent control to vary the output voltage VoIs controlled at VominAnd VomaxIn the meantime.
As shown in fig. 2, at t0Time-to-time switching tube Q7After adopting intermittent control, the switching tube Q7When the circuit is in the mode 1 operation state, as shown in fig. 3(a), the photovoltaic power supply supplies energy to the load and stores the excess energy in the storage battery through the resonant circuit, and the output voltage V isoRising; when t is1Time output voltage VoRising to the maximum value V of the preset output voltageomaxTime, switch tube Q7The secondary side is disconnected by switching off, the circuit is in the mode 2 operation state, as shown in fig. 3(b), at this time, the photovoltaic power supply only charges the storage battery, and the output voltage VoDescending; when t is2The output voltage drops to the minimum value V of the preset output voltage at the momentominTime, switch tube Q7And conducting again, and repeating the steps.
MATLAB/Simulink simulation software is utilized to carry out simulation analysis on the three-port photovoltaic energy storage LLC resonant converter circuit under the light-load working condition, and rated output voltage V is setoTo 12V, a preset maximum value V of output voltage is setomaxAt 12.2V, set upPresetting a minimum value V of output voltageominIt was 11.8V. Referring to FIG. 4, the upper graph shows the output voltage waveform, and the lower graph shows the switching tube Q7And driving the waveform, wherein the obtained simulated oscillogram conforms to the proposed light load control strategy, and the feasibility of the light load control strategy is verified.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (4)
1. A three-port photovoltaic energy storage LLC resonant converter is used for realizing power flow among a photovoltaic power supply, a storage battery and a load. The method is characterized in that: accumulator connecting switch tube Q1、Q2Constructed in a half-bridge configuration via a resonant inductor LrConnecting a pair of reverse switch tubes Q5、Q6Switching tube Q5、Q6And a resonance capacitor CrParallel connection; photovoltaic power supply connection switch tube Q3、Q4Constructed in a half-bridge configuration via an excitation inductance LmConnecting resonant capacitor Cr(ii) a The secondary side of the transformer passes through a diode D1、D2、D3、D4The formed rectifier bridge is connected with a mode switching tube Q7Through a filter capacitor CoA load is connected.
2. A light-load control strategy of a three-port photovoltaic energy storage LLC resonant converter is characterized in that: when the circuit operates under light load condition, the switch tube Q1、Q2Switching tube Q alternatively conducted and switched at fixed frequency3Conducting, Q4Turn-off and reverse connection switch tube Q5、Q6And conducting. When the output voltage V isoHigher than a predetermined maximum voltage VomaxTime switch tube Q7The whole secondary side circuit is disconnected by switching off, and the photovoltaic power supply stores energy into the storage battery through the primary side loop and outputs the energyThe output voltage is reduced; when the output voltage V isoBelow a predetermined minimum voltage VominTime switch tube Q7And (4) conducting, transmitting energy to the load through the transformer on the primary side, and increasing the output voltage repeatedly.
3. The three-port photovoltaic energy-storing LLC resonant converter light-load control strategy as claimed in claim 2, characterized in that: the switching tube Q operating at a fixed frequency1、Q2Is given according to circuit specific design parameters.
4. The three-port photovoltaic energy-storing LLC resonant converter light-load control strategy as claimed in claim 2, characterized in that: the preset maximum voltage VomaxPresetting minimum voltage VominThe ripple requirement of the output voltage is set according to the actual application.
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| 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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| 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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| CN114142738B CN114142738B (en) | 2023-10-03 |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20140183953A1 (en) * | 2012-12-30 | 2014-07-03 | Enphase Energy, Inc. | Three port converter with dual independent maximum power point tracking and dual operating modes |
| CN103944396A (en) * | 2014-04-11 | 2014-07-23 | 燕山大学 | LLC resonance type three-port DC-DC converter and control method thereof |
| US20150124487A1 (en) * | 2013-11-04 | 2015-05-07 | Futurewei Technologies, Inc. | Adjustable Resonant Apparatus for Power Converters |
| 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 |
-
2021
- 2021-12-09 CN CN202111502225.3A patent/CN114142738B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20140183953A1 (en) * | 2012-12-30 | 2014-07-03 | Enphase Energy, Inc. | Three port converter with dual independent maximum power point tracking and dual operating modes |
| US20150124487A1 (en) * | 2013-11-04 | 2015-05-07 | Futurewei Technologies, Inc. | Adjustable Resonant Apparatus for Power Converters |
| 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 |
|---|
| ABHISHEK AWASTHI等: ""Variable Frequency-duty cycle modulation technique for light load efficiency improvement of LLC resonant converter for wide input voltage range in PV applications"", 《2019 CPERE会议》 * |
| 冯兴田;邵康;崔晓;马文忠;王玉彬;: "基于多模态切换的宽电压增益LLC谐振变换器控制策略", 电工技术学报, no. 20 * |
| 李微;王议锋;韩富强;陈博;: "一种隔离型三端口双向LCLC多谐振直流变换器", 电工技术学报, no. 14 * |
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