CN110957922A - Single-stage high-frequency isolated bidirectional direct-current converter and grid-connected energy storage system - Google Patents

Single-stage high-frequency isolated bidirectional direct-current converter and grid-connected energy storage system Download PDF

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Publication number
CN110957922A
CN110957922A CN201911251918.2A CN201911251918A CN110957922A CN 110957922 A CN110957922 A CN 110957922A CN 201911251918 A CN201911251918 A CN 201911251918A CN 110957922 A CN110957922 A CN 110957922A
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China
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module
resonance
energy storage
transformer
input
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Chinese (zh)
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胡咸兵
邓礼宽
柏建国
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Shenzhen Uugreenpower Electrical Co ltd
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Shenzhen Uugreenpower Electrical Co ltd
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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
    • H02M3/33569—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 several active switching elements
    • H02M3/33576—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 several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33584—Bidirectional converters
    • 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
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • 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
    • H02M3/33569—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 several active switching elements
    • H02M3/33576—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 several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33592—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 several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
    • 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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention relates to a single-stage high-frequency isolated bidirectional direct current converter, which comprises: the transformer type transformer energy-saving control system comprises a boosting energy-storing module, an input switch network, a transformer module, a resonance module, an output switch network and a switching control module, wherein the boosting energy-storing module, the input switch network, the transformer module, the resonance module and the output switch network are sequentially and electrically connected, and the switching control module is in control connection with the boosting energy-storing module and the resonance module; the switching control module is used for controlling the boost energy storage module to be switched in and the resonance module to be switched out during forward conversion, and controlling the boost energy storage module to be switched out and the resonance module to be switched in during reverse conversion. The invention also relates to a grid-connected energy storage system. By adopting the switching control module, the single-stage topological structure with low cost and high efficiency can meet the wide input voltage range.

Description

Single-stage high-frequency isolated bidirectional direct-current converter and grid-connected energy storage system
Technical Field
The invention relates to the field of power modules, in particular to a single-stage high-frequency isolated bidirectional direct-current converter and a grid-connected energy storage system comprising the same.
Background
With the increasing development of energy crisis and the improvement of environmental awareness of people, the green and efficient utilization of energy becomes the key point for research and application in various countries, and the research on high-frequency isolation type wide-range direct current converters is more important. At present, in engineering application, a single-stage high-frequency isolated bidirectional direct-current converter is generally too narrow in input voltage range and cannot meet the requirement of wide input voltage range. However, the bidirectional high-frequency isolated dc converter with a wide input voltage range mostly adopts a two-stage topology structure. For example, the BUCKBOOST + LLC circuit is cascaded, the input voltage range is improved through the BUCKBOOST circuit, and high-frequency isolation is realized through a transformer of the LLC circuit. Or the BUCKBOOST + phase-shifted full-bridge circuit is cascaded, the input voltage range is also enlarged through the BUCKBOOST circuit, and high-frequency isolation is realized through a transformer of the phase-shifted full-bridge circuit. However, compared with a single-stage topology structure, the BuckBOOST + LLC circuit cascade or the BuckBOOST + phase-shifted full-bridge circuit cascade increases the cost of the switch device and reduces the energy conversion efficiency.
Disclosure of Invention
The present invention is directed to solve the above-mentioned problems of the prior art, and provides a single-stage high-frequency isolated bidirectional dc converter and a grid-connected energy storage system including the same, wherein the single-stage topology structure used in a low-cost and high-efficiency manner satisfies a wide input voltage range.
The technical scheme adopted by the invention for solving the technical problems is as follows: a single-stage high-frequency isolated bidirectional direct current converter is constructed, and comprises: the transformer type transformer energy-saving control system comprises a boosting energy-storing module, an input switch network, a transformer module, a resonance module, an output switch network and a switching control module, wherein the boosting energy-storing module, the input switch network, the transformer module, the resonance module and the output switch network are sequentially and electrically connected, and the switching control module is in control connection with the boosting energy-storing module and the resonance module; the switching control module is used for controlling the boost energy storage module to be switched in and the resonance module to be switched out during forward conversion, and controlling the boost energy storage module to be switched out and the resonance module to be switched in during reverse conversion.
In the single-stage high-frequency isolated bidirectional direct current converter, the resonance module comprises a first resonance unit and a second resonance unit, the first resonance unit is connected between a first secondary side end of the transformer module and a first input end of the output switch network, and the second resonance unit is connected between the first secondary side end and a second secondary side end of the transformer module through the resonance switching control unit.
In the single-stage high-frequency isolated bidirectional direct-current converter, the switching control module comprises a boost switching control unit for controlling the boost energy storage module to be put in during forward conversion and controlling the boost energy storage module to be put out during reverse conversion, and a resonance switching control unit for controlling the first resonance unit and the second resonance unit to be put out during forward conversion and controlling the first resonance unit and the second resonance unit to be put in during reverse conversion.
In the single-stage high-frequency isolated bidirectional direct current converter, the first resonance unit comprises a first inductor and a first capacitor, the second resonance unit comprises a second inductor, a first end of the first inductor is connected with a first end of a secondary side of the transformer module, and a second end of the first inductor is connected with a first input end of the output switch network through the first capacitor; and the first end of the second inductor is connected with the first end of the secondary side of the transformer module through the resonance switching control unit, and the second end of the second inductor is connected with the second end of the secondary side of the transformer module.
In the single-stage high-frequency isolated bidirectional dc converter of the present invention, the resonant switching control unit includes a first resonant switch connected in parallel to the first inductor and a second resonant switch connected in series to the second inductor.
In the single-stage high-frequency isolated bidirectional direct current converter, the boost energy storage module comprises a boost energy storage inductor connected between the positive electrode of the input power supply and the first input end of the input switch network.
In the single-stage high-frequency isolated bidirectional direct current converter, the boost switching control unit comprises boost switching switches connected in parallel at two ends of the boost energy storage inductor.
In the single-stage high-frequency isolated bidirectional dc converter of the present invention, the boost energy storage module further includes an input filter capacitor connected between the positive electrode and the negative electrode of the output power supply, and an absorption unit connected between the first input terminal and the second input terminal of the input switch network.
In the single-stage high-frequency isolated bidirectional direct current converter, the input switch network and the output switch network comprise a full-bridge switch tube network or a half-bridge switch tube network; the absorption unit comprises an absorption diode, an absorption capacitor and an absorption resistor, wherein the anode of the absorption diode is connected with the first input end of the input switch network, the cathode of the absorption diode is connected with the second input end of the input switch network through the absorption capacitor, and the absorption resistor is connected in parallel at the two ends of the absorption diode or the absorption capacitor.
According to another technical scheme adopted for solving the technical problems, the grid-connected energy storage system is constructed and comprises a battery module, a photovoltaic assembly, a DC/DC module, a DC filtering module, a DC/AC module, an AC filtering module, a relay, a load, a power grid module and the single-stage high-frequency isolation type bidirectional direct current converter, wherein the photovoltaic assembly is connected to the DC filtering module through the DC/DC module, the battery module is connected to the DC filtering module through the single-stage high-frequency isolation type bidirectional direct current converter, and the DC filtering module is further connected with the load or the power grid module through the DC/AC module, the AC filtering module and the relay in sequence.
According to the single-stage high-frequency isolated bidirectional direct current converter and the grid-connected energy storage system, the switching control module is adopted, the boosting energy storage module and the resonance module are thrown in during forward conversion, so that the voltage in a wide input range is converted into relatively stable output voltage, and the boosting energy storage module and the resonance module are thrown out during reverse conversion, so that the relatively stable input voltage is converted into the output voltage in the wide output range, and therefore, the single-stage topological structure in a low-cost and high-efficiency mode can meet the wide input voltage range. Compared with a pure resonance type LLC converter, the input voltage range can be improved, and no extra circuit is required to be added. Compared with the traditional phase-shifted full-bridge converter, the input voltage range can be improved; and the efficiency of the direct current power reverse conversion can be improved by utilizing the topological advantage of the LLC.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic block diagram of a first preferred embodiment of a single-stage, high frequency isolated, bidirectional DC converter of the present invention;
FIG. 2 is a schematic block diagram of a second preferred embodiment of the single-stage, high frequency isolated, bidirectional DC converter of the present invention;
FIG. 3 is a circuit diagram of a third preferred embodiment of the single-stage, high frequency isolated, bi-directional DC converter of the present invention;
4A-4C are schematic diagrams illustrating charging energy, positive and negative energy transfer during forward conversion of the single-stage high-frequency isolated bidirectional DC converter shown in FIG. 3;
FIG. 5 is a schematic diagram of the switching tube driving waveform of the DC forward conversion of the single-stage high-frequency isolated bidirectional DC converter shown in FIG. 3;
fig. 6 is a control block diagram of the dc forward conversion of the single-stage high-frequency isolated bidirectional dc converter shown in fig. 3;
7A-7B illustrate schematic diagrams of positive and negative energy transfer during reverse conversion of the single-stage high frequency isolated bidirectional DC converter shown in FIG. 3;
fig. 8 is a schematic diagram of switching tube driving wave generation of dc inverse transformation of the single-stage high-frequency isolated bidirectional dc converter shown in fig. 3;
fig. 9 is a control block diagram of the dc-reverse conversion of the single-stage high-frequency isolated bidirectional dc converter shown in fig. 3;
FIGS. 10A-10B are schematic diagrams of an application circuit of the single-stage high-frequency isolated bidirectional DC converter of the present invention;
fig. 11 is a circuit diagram of a fourth preferred embodiment of the single-stage high-frequency isolated bidirectional dc converter of the present invention;
FIG. 12 is a functional block diagram of a first preferred embodiment of a grid-tied energy storage system of the present invention;
13A-13C illustrate single phase alternative implementations of DA/AC modules;
FIGS. 14A-14C illustrate three-phase alternative implementations of the DA/AC module.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention relates to a single-stage high-frequency isolated bidirectional direct current converter, which comprises: the transformer type transformer energy-saving control system comprises a boosting energy-storing module, an input switch network, a transformer module, a resonance module, an output switch network and a switching control module, wherein the boosting energy-storing module, the input switch network, the transformer module, the resonance module and the output switch network are sequentially and electrically connected, and the switching control module is in control connection with the boosting energy-storing module and the resonance module; the switching control module is used for controlling the boost energy storage module to be switched in and the resonance module to be switched out during forward conversion, and controlling the boost energy storage module to be switched out and the resonance module to be switched in during reverse conversion. According to the invention, the switching control module is adopted, the boosting energy storage module and the resonance module are put in during forward conversion to realize the conversion of the voltage in a wide input range to the relatively stable output voltage, and the boosting energy storage module and the resonance module are put in during reverse conversion to convert the relatively stable input voltage to the output voltage in the wide output range, so that the single-stage topological structure in a low-cost and high-efficiency mode can meet the wide input voltage range.
The bidirectional dc conversion system is essential to the requirements of voltage conversion range, power density, cost, volume and efficiency. However, since the conventional topology generally adopts a two-stage structure, the input voltage range is increased by additionally adding a one-stage buck-boost circuit. Therefore, the traditional two-stage topology structure inevitably leads to a series of problems of increased cost, reduced power density, reduced conversion efficiency, increased control difficulty and the like due to the increase of switching devices. Most of the existing products adopt series-parallel connection of a plurality of circuits to combine a bidirectional direct current converter with larger capacity and wider range. However, the inventor of the present application creatively thinks that the BOOST module is combined with the high-frequency isolation type dc conversion module, and the BOOST module is combined with the high-frequency transformer to achieve the purpose of boosting and reducing voltage; the bidirectional direct current reverse conversion adopts the traditional LLC resonant circuit to reduce the switching loss and improve the system efficiency, and the measure breaks through a conventional thought mode in the field.
Fig. 1 is a schematic block diagram of a first preferred embodiment of the single-stage high-frequency isolated bidirectional dc converter of the present invention. As shown in fig. 1, the single-stage high-frequency isolated bidirectional dc converter of the present invention includes: the boost energy storage module 100, the input switch network 200, the transformer module 300, the resonance module 400, the output switch network 500 that connect electrically in proper order, and with boost energy storage module 100 with the switching control module 600 of resonance module 400 control connection, boost energy storage module 100 connects the positive pole and the negative pole of input power. The switching control module 600 is configured to control the boost energy storage module 100 to be switched in and the resonance module 400 to be switched out during forward conversion, and control the boost energy storage module 100 to be switched out and the resonance module 400 to be switched in during reverse conversion.
In a preferred embodiment of the present invention, the boost energy storage module 100 may be constructed using any known capacitor and inductor. The transformer module 300 may include one or more transformers connected in series. The input switching network 200 and the output switching network 500 may comprise any known full-bridge switching transistor network or half-bridge switching transistor network. The resonance module 400 may be any LLC resonance module, CLLC resonance module, LC resonance module, etc. The switching control module 600 may be any hardware switch or circuit, such as an air switch, a power switch tube, a relay or a contactor, or any soft switch module or device.
According to the invention, the switching control module is adopted, the boosting energy storage module and the resonance module are put in during forward conversion to realize the conversion of the voltage in a wide input range to the relatively stable output voltage, and the boosting energy storage module and the resonance module are put in during reverse conversion to convert the relatively stable input voltage to the output voltage in the wide output range, so that the single-stage topological structure in a low-cost and high-efficiency mode can meet the wide input voltage range.
Fig. 2 is a schematic block diagram of a second preferred embodiment of the single-stage high-frequency isolated bidirectional dc converter of the present invention. In the embodiment shown in fig. 2, the single-stage high-frequency isolated bidirectional dc converter of the present invention includes: the boost energy storage module 100, the input switch network 200, the transformer module 300, the resonance module 400, the output switch network 500 that connect electrically in proper order, and with boost energy storage module 100 with the switching control module 600 of resonance module 400 control connection, boost energy storage module 100 connects the positive pole and the negative pole of input power. Further the resonator module 400 comprises a first resonator element 410 and a second resonator element 420.
The first resonant unit 410 is connected between the first end of the secondary side of the transformer module 300 and the first input terminal of the output switching network 500, and the second resonant unit 420 is connected between the first end of the secondary side and the second end of the secondary side of the transformer module 300. The switching control module 600 includes a boost switching control unit 610 for controlling the boost energy storage module 100 to be switched in during forward conversion and controlling the boost energy storage module 100 to be switched out during reverse conversion, and a resonance switching control unit 620 for controlling the first resonance unit 410 and the second resonance unit 420 to be switched out during forward conversion and controlling the first resonance unit 410 and the second resonance unit 420 to be switched in during reverse conversion.
In a preferred embodiment of the present invention, the boost energy storage module 100 may be constructed using any known capacitor and inductor. The transformer module 300 may include one or more transformers connected in series. The input switching network 200 and the output switching network 500 may comprise any known full-bridge switching transistor network or half-bridge switching transistor network. First resonance unit 410 and second resonance unit 420 may be any LC resonance module. The boost switching control unit 610 and the resonant switching control unit 620 may be any hardware switch or circuit, such as an air switch, a power switch tube, a relay or a contactor, or any soft switch module, or device.
According to the invention, the switching control module is adopted, the boosting energy storage module and the resonance module are put in during forward conversion to realize the conversion of the voltage in a wide input range to the relatively stable output voltage, and the boosting energy storage module and the resonance module are put in during reverse conversion to convert the relatively stable input voltage to the output voltage in the wide output range, so that the single-stage topological structure in a low-cost and high-efficiency mode can meet the wide input voltage range.
Fig. 3 is a circuit diagram of a third preferred embodiment of the single-stage high-frequency isolated bidirectional dc converter of the present invention. As shown in fig. 3, the single-stage high-frequency isolated bidirectional dc converter of the present invention includes: the boost energy storage module 100, the input switch network 200, the transformer module 300, the resonance module 400, the output switch network 500 that connect electrically in proper order, and with boost energy storage module 100 with the switching control module 600 of resonance module 400 control connection, boost energy storage module 100 connects the positive pole and the negative pole of input power. Further the resonator module 400 comprises a first resonator element 410 and a second resonator element 420. The switching control module 600 includes a boost switching control unit 610 and a resonant switching control unit 620.
In the preferred embodiment shown in FIG. 3, the boost energy storage module 100 includes an input filter capacitor C connected between the positive and negative poles BAT + and BAT-of the input power supplyinAnd a boost energy storage inductor L connected between the input power supply anode BAT + and the first input terminal of the input switch network 200boost. The input switching network 200 includes a switching tube Q1-Q4And an antiparallel diode D1-D4And forming a full-bridge switching tube network. The first resonance unit 410 includes a first inductance LrAnd a first capacitor C1The second resonance unit 420 includes a second inductor Lm. The first inductor LrIs connected to the secondary first end of the transformer module 300. A second terminal connected to the first capacitor C1A first input of the output switching network 500 is connected. The second inductor LmIs connected to the first secondary end of the transformer module 300 via the resonant switching control unit 620, and the second inductor LmIs connected to the secondary side second terminal of the transformer module 300. The output switch network 500 comprises a switch tube Q5-Q8And an antiparallel diode D5-D8And forming a full-bridge switching tube network. Further, the output switch network 500 may further include an output filter capacitor Cout. The output filter capacitor CoutBoth ends of the positive and negative bus bars are connected.
In this embodiment, the resonant switching control unit includes the first inductor LrParallel first resonant switch KllcAnd the second inductor LmSecond resonant switch K connected in seriesm. The boost switching control unit comprises a boost energy storage inductor L connected in parallelboostBoost switching switch K at two endsboost. In the preferred embodiment, the first resonant switch KllcA second resonant switch KmAnd boost switching switch KboostAn air switch is used. In a preferred embodiment of the present invention, the switch tube may be a metal-oxide semiconductor field effect transistor, an insulated gate bipolar transistor, a power transistor, an insulated gate field effect transistor, a gate turn-off thyristor or a thyristor. The input end of the boost energy storage module 100 may be connected to a battery module or a load module, a single-phase passive power factor correction circuit, a single-phase active power factor correction circuit, a three-phase passive power factor correction circuit, or a three-phase active power factor correction circuit.
In a further preferred embodiment of the invention, the boost energy storage module further comprises a sinking unit connected between the first input and the second input of the input switching network. In the embodiment shown in fig. 11, the absorption unit comprises an absorption diode DfAnd an absorption capacitor CfAnd an absorption resistance Rf. The above-mentionedAbsorption diode DfIs connected to a first input terminal of the input switching network 200, and has a cathode connected to the absorption capacitor CfConnected to a second input terminal of the input switching network 200, the absorption resistor RfIs connected in parallel with the absorption capacitor CfTwo ends. Of course, the absorption resistance RfCan also be connected to the absorption diode DfTwo ends. In other preferred embodiments of the invention, the absorbent unit may also take other configurations, or include other elements.
Fig. 4A-4C and fig. 7A-7B show charging energy, positive and negative energy transfer diagrams for a forward transform, and positive and negative energy transfer diagrams for a reverse transform, respectively. Fig. 5 and 8 show the driving wave-generating diagrams of the switching tube with direct current forward and reverse conversion respectively. Fig. 6 and 9 show control block diagrams of the dc forward conversion and the dc reverse conversion thereof, respectively. Fig. 10A-10B show application circuit schematics. The principles of the present invention are described below in conjunction with fig. 3-10B.
In the forward transform stage:
in step one, the air switch K is turned offboostOff air switch KlmClosing air switch KllcAnd the BOOST and the buck of the input power side output side are realized by combining the BOOST and the transformer module.
In the second step, the high-voltage side full-bridge circuit switching tube of the transformer module is controlled according to the following mode: switch tube Q1And a switching tube Q3Drive the same, switch tube Q2And a switching tube Q4Drive the same, switch tube Q1And a switching tube Q2The driving duty ratio is the same, and the phases are staggered by 180 degrees;
in step three, when the high-voltage side switch tube Q of the transformer module1And a switching tube Q2And a switching tube Q3And a switching tube Q4When all are conducted, the input power is supplied to the inductor LboostCharging; low-voltage side switch tube Q of transformer module at the moment5And a switching tube Q6And a switching tube Q7And a switching tube Q8Are all turned off, and the specific circuit schematic is shown in fig. 4A.
In step four, when the high-voltage side switch tube Q of the transformer module1And a switching tube Q3Conducting, switching tube Q2And a switching tube Q4When the power is turned off, the power is input to the inductor LboostAre all discharged; low-voltage side switch tube Q of transformer module at the moment5And a switching tube Q7Conducting, switching tube Q6And a switching tube Q8Turning off and carrying out synchronous rectification; the specific circuit schematic is shown in fig. 4B.
In step five, when the high-voltage side of the transformer module is switched on or off, the transistor Q1And a switching tube Q3Turn-off, switch tube Q2And a switching tube Q4When conducting, the power supply and the inductor LboostAre all discharged; low-voltage side switch tube Q of transformer module at the moment5And a switching tube Q7Turn-off, switch tube Q6And a switching tube Q8Conducting and carrying out synchronous rectification; the specific circuit schematic is shown in fig. 4C.
The forward conversion control aims at stabilizing the voltage at the output side (namely the bus voltage), limiting power and improving current ripple, so that voltage-current double closed-loop control is adopted: calculating a current reference value by a BUS voltage PI loop, calculating a BOOST boosting duty ratio by the current PI loop, and calculating the duty ratio of an actual control switching tube by the aid of a feed-forward quantity; the specific wave generation control mode is shown in fig. 5, and the control block diagram is shown in fig. 6.
In the reverse transformation stage:
in step one, the air switch K is closedboostClosing the air switch KlmOff the air switch KllcThe LLC resonance module is combined with the transformer module to realize voltage boosting and reducing of the output side to the power supply side; switch tube Q1And a switching tube Q2And a switching tube Q3And a switching tube Q4And a switching tube Q5And a switching tube Q6And a switching tube Q7And a switching tube Q8All controlled with a constant duty cycle, and the control of the reverse output voltage is realized by adjusting the switching frequency (frequency modulation).
In the second step, the low-voltage side full-bridge circuit switching tube of the transformer module is controlled according to the following mode: switch tube Q5And a switching tube Q7Drive the same, switch tube Q6And a switching tube Q8Drive the same, switch tube Q5And a switching tube Q8The driving is complementary, and the duty ratio is controlled by adjusting the dead time.
In step three, when the low-voltage side switch tube Q of the transformer module5And a switching tube Q7Conducting, switching tube Q6And a switching tube Q8When the power supply is turned off, the output side transmits energy to the power supply side through the transformer module; high-voltage side switch tube Q of transformer module at the moment1And a switching tube Q3Conducting, switching tube Q2And a switching tube Q4Turning off and carrying out synchronous rectification; the specific circuit schematic is shown in fig. 7A.
In step four, when the low-voltage side switch tube Q of the transformer module5And a switching tube Q7Turn-off, switch tube Q6And a switching tube Q8When the power supply is conducted, the output side transmits energy to the power supply side through the transformer module; high-voltage side switch tube Q of transformer module at the moment1And a switching tube Q3Turn-off, switch tube Q2And a switching tube Q4Conducting and carrying out synchronous rectification; the specific circuit schematic is shown in fig. 7B.
The reverse conversion control aims at stabilizing the power supply voltage and limiting the power, and adopts voltage and current double closed-loop control: calculating a current reference value by a power supply voltage PI loop, calculating an LLC frequency adjustment quantity by the current PI loop, and finally adding a feedforward quantity to calculate the frequency of an actual control switch; the specific wave generation control method is shown in fig. 8, and the control block diagram is shown in fig. 9. In the constant current control stage, a power supply voltage PI ring is saturated; in the constant voltage control stage and the floating charge stage, the power supply voltage PI ring is desaturated.
According to the single-stage high-frequency isolated bidirectional direct current converter, the BOOST circuit and the high-frequency isolated LLC resonance module are innovatively combined to achieve the function of boosting the high-voltage side of the high-frequency transformer, and then the high-frequency transformer is used for reducing voltage in a transformation ratio manner, and a low-voltage side can use a low-voltage-resistant switch device, so that the cost is saved; on the premise of effectively widening the input voltage range, a switching device is not added, the system volume can be reduced, and the control is simplified; the invention realizes bidirectional direct current conversion with wide input voltage range by a single-stage power conversion circuit, and can improve the conversion efficiency of the system. The voltage and current double closed-loop control strategy is simple to control and convenient to popularize and apply; and the compact single-stage power conversion is adopted, so that the efficiency is higher and the cost is lower.
Fig. 12 is a schematic block diagram of a first preferred embodiment of the grid-connected energy storage system of the present invention. As shown in fig. 12, the grid-connected energy storage system includes a battery module 101, a photovoltaic module 301, a DC/DC module 401, a DC filter module 501, a DC/AC module 601, an AC filter module 701, a relay 801, a load 1001, a grid module 901, and a single-stage high-frequency isolated bidirectional DC converter 201. The photovoltaic module 301 is connected to the DC filter module 501 through a DC/DC module 401, the battery module 101 is connected to the DC filter module 501 through the single-stage high-frequency isolated bidirectional DC converter 201, and the DC filter module is further connected to a load 10011 or a power grid module 901 through a DC/AC module 601, an AC filter module 701 and a relay 801 in sequence.
Those skilled in the art will appreciate that any relevant modules known in the art may be used for the battery module 101, the photovoltaic module 301, the DC/DC module 401, the DC filtering module 501, the DC/AC module 601, the AC filtering module 701, the relay 801, the load 1001, and the grid module 901. Fig. 13A-13C show a single phase alternative implementation of the DA/AC module. FIGS. 14A-14C illustrate three-phase alternative implementations of the DA/AC module. The photovoltaic module 301 may be a PV photovoltaic module. The single-stage high-frequency isolated bidirectional dc converter 201 may be constructed in accordance with any of the embodiments described above.
In the preferred embodiment of the present invention, a current sensor is connected in series in the loop of the battery module 101; a current sensor is connected in series in the PV photovoltaic module 301 loop; a current sensor is connected in series in the loop of the power grid module 901; a current sensor is connected in series in the load 1001 loop; the input and output alternating voltages of the relay network 801 are sampled through a voltage sensor respectively; direct-current voltages at two ends of the battery module 101, the PV photovoltaic module 301 and the DC filter module 501 are sampled through resistor series-parallel connection and a linear optical coupling circuit respectively.
The working principle of the grid-connected energy storage system of the invention is described in detail below, and the specific steps are as follows:
step one, detecting the access conditions of the battery module 101, the PV photovoltaic module 301 and the power grid module 901.
Step two, if only the battery module 101 is operated in the off-grid operation mode: the battery module 101 discharges and supplies power to the load 1001.
Step three, if only the PV photovoltaic module 301 is operating in the off-grid operating mode: the PV photovoltaic module 301 discharges and supplies power to the load 1001.
Step four, if only the power grid module 901 is accessed, the system works in a grid-connected operation mode: the grid module 901 supplies power to a load 1001.
Step five, if only the PV photovoltaic module 301 and the power grid module 901 are connected, the PV photovoltaic module works in the grid-connected operation mode, which is the same as that of the photovoltaic grid-connected inverter: firstly, bus soft start mainly controls a non-isolated DC/DC module 401 to convert the voltage of the PV photovoltaic module 301 into an ideal voltage for output; secondly, software phase locking is mainly performed on the phase of the power grid module 901; thirdly, relay detection, which is mainly to detect the relay module 801, close the relay and connect the power grid module 901 and the load 1001 into the system; finally, maximum power tracking, which is mainly performed on the PV photovoltaic module 301.
Step six, if only the PV photovoltaic modules 301 and the battery modules 101 are accessed, the PV photovoltaic modules operate in an off-grid operation mode: during light load, the energy of the PV photovoltaic module 301 is transmitted to the battery module 101 and the load 1001, and the battery module 101 is in a charging mode; during heavy loads, the PV module 301 and the battery module 101 are powered to the load 1001, and the battery module 101 is in a discharge mode.
Step seven, if only the battery module 101 and the power grid module 901 are accessed, the photovoltaic grid-connected inverter works in a grid-connected operation mode similar to that of a photovoltaic grid-connected inverter: firstly, the bus is soft started, and mainly a single-stage high-frequency isolated bidirectional direct current converter 201 is controlled to convert the voltage of a battery module 101 into an ideal voltage for output; secondly, software phase locking is mainly performed on the phase of the power grid module 901; thirdly, relay detection, which is mainly to detect the relay module 801, close the relay and connect the power grid module 901 and the load 1001 into the system; finally, the power flow of the battery module 101 is controlled to mainly determine whether the battery module 101 is in the charging mode or the discharging mode.
Step eight, if the battery module 101, the PV photovoltaic module 301 and the power grid module 901 are connected, the photovoltaic grid-connected inverter works in a grid-connected operation mode similar to that of a photovoltaic grid-connected inverter: firstly, bus soft start mainly controls a single-stage high-frequency isolated bidirectional direct current converter 201 to convert the voltage of a battery module 101 into ideal voltage for output or controls a non-isolated DC/DC module 401 to convert the voltage of a PV photovoltaic module 301 into ideal voltage for output; secondly, software phase locking is mainly performed on the phase of the power grid module 901; thirdly, relay detection, which is mainly to detect the relay network 801, close the relay and connect the power grid module 901 and the load 1001 into the system; finally, the maximum power tracking is mainly to perform maximum power point tracking on the PV photovoltaic module 301, and meanwhile, to determine the power flow direction of the battery module 101, i.e., whether the battery module 101 is in the charging mode or the discharging mode.
Further analyzing the charging and discharging principle of the single-stage high-frequency isolated bidirectional DC converter 201
A discharging operation mode:
in step one, the air switch K is turned offboostOff air switch KlmClosing air switch KllcAnd the BOOST and the buck of the input power side output side are realized by combining the BOOST and the transformer module. The discharge voltage increasing and decreasing and high-frequency isolation functions of the battery module 101 are realized by adjusting the duty ratio of a high-voltage side switch tube of the transformer module and a low-voltage side switch tube of the transformer module,
the method specifically comprises the following steps: the duty ratio of a high-voltage side switching tube of the transformer module is soft up to 50% at most, an initial duty ratio value is obtained, the driving duty ratios of the switching devices of the same bridge arm are the same, the phases of the switching devices are staggered by 180 degrees, and the driving of the switching devices opposite to each other among different bridge arms is the same. The required voltage of the DC filter module 501 is given as a discharge voltage closed-loop reference value, and the actual DC voltage at the two ends of the DC filter module 501 is given as a discharge voltage closed-loop feedback value to output a discharge current closed-loop given value. And taking the current value sampled by the series current sensor in the loop of the battery module 101 as the feedback value of the discharge current closed loop, and outputting the duty ratio adjustment quantity of the high-voltage side switching tube of the transformer module.
And adding the calculated duty ratio adjustment quantity and the initial duty ratio to obtain the duty ratio of a switching device of a high-voltage side switching tube of the actual control transformer module. The duty ratio of the switching device is used as reference, the duty ratio required by synchronous rectification control of a low-voltage side switching tube of the transformer module is calculated and is slightly smaller than an ideal calculated value, and energy backflow is avoided.
And (3) a charging operation mode:
closed air switch KboostClosing the air switch KlmOff the air switch KllcThe LLC resonance module is combined with the transformer module to realize voltage boosting and reducing of the output side to the power supply side; the functions of charging voltage increase and reduction and high-frequency isolation are realized by adjusting the switching frequency and the duty ratio of a high-voltage side switching tube of the transformer module and a low-voltage side switching tube of the transformer module,
the method specifically comprises the following steps: according to the switching frequency and the duty ratio which are initially set, the dead time of a low-voltage side switching tube of the transformer module is slowly reduced until the dead time reaches a set value, switching devices of the same bridge arm are complementary, and the opposite switching devices among different bridge arms are driven to be the same.
And setting the required voltage of the battery module 101 as a charging voltage closed-loop reference value, taking the actual direct current voltage at two ends of the battery module 101 as a charging voltage closed-loop feedback value, and outputting a charging current closed-loop set value.
And taking the current value sampled by the series current sensor in the loop of the battery module 101 as the feedback value of the reverse current closed loop, and outputting the switching frequency adjustment quantity of the low-voltage side switching tube of the transformer module.
And adding the calculated switching frequency adjustment quantity and the initially set switching frequency to obtain the switching frequency of a low-voltage side switching tube of the actual control transformer module. And calculating the switching frequency and the duty ratio required by synchronous rectification control of the high-voltage side switching tube of the transformer module by taking the calculated switching frequency and the calculated duty ratio of the low-voltage side switching tube of the actual control transformer module as reference, wherein the frequency is the same, and the duty ratio is slightly smaller than an ideal calculated value, so that energy reverse irrigation is avoided.
According to the grid-connected energy storage system, the BOOST boosting and high-frequency isolation LLC resonance module is innovatively combined to realize the boosting function on the high-voltage side of the high-frequency transformer, the voltage is reduced through the transformation ratio of the high-frequency transformer, and a low-voltage-resistant switching device can be used on the low-voltage side of the high-frequency transformer, so that the cost is saved; on the premise of effectively widening the input voltage range, a switching device is not added, the system volume can be reduced, and the control is simplified; the invention realizes bidirectional direct current conversion with wide input voltage range by a single-stage power conversion circuit, and can improve the conversion efficiency of the system. The voltage and current double closed-loop control strategy is simple to control and convenient to popularize and apply; and the compact single-stage power conversion is adopted, so that the efficiency is higher and the cost is lower.
While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (10)

1. A single-stage high-frequency isolated bidirectional DC converter, comprising: the transformer type transformer energy-saving control system comprises a boosting energy-storing module, an input switch network, a transformer module, a resonance module, an output switch network and a switching control module, wherein the boosting energy-storing module, the input switch network, the transformer module, the resonance module and the output switch network are sequentially and electrically connected, and the switching control module is in control connection with the boosting energy-storing module and the resonance module; the switching control module is used for controlling the boost energy storage module to be switched in and the resonance module to be switched out during forward conversion, and controlling the boost energy storage module to be switched out and the resonance module to be switched in during reverse conversion.
2. The single-stage high-frequency isolated bidirectional direct current converter according to claim 1, wherein the switching control module includes a boost switching control unit for controlling the boost energy storage module to be switched on during forward conversion and controlling the boost energy storage module to be switched off during reverse conversion, and a resonance switching control unit for controlling the first resonance unit and the second resonance unit to be switched off during forward conversion and controlling the first resonance unit and the second resonance unit to be switched on during reverse conversion.
3. The single-stage high-frequency isolated bidirectional direct current converter according to claim 2, wherein the resonant module comprises a first resonant unit and a second resonant unit, the first resonant unit is connected between the secondary side first end of the transformer module and the first input end of the output switch network, and the second resonant unit is connected between the secondary side first end and the secondary side second end of the transformer module through the resonant switching control unit.
4. The single-stage high-frequency isolated bidirectional direct current converter according to claim 3, wherein the first resonant unit comprises a first inductor and a first capacitor, the second resonant unit comprises a second inductor, a first end of the first inductor is connected to a first end of a secondary side of the transformer module, and a second end of the first inductor is connected to a first input end of the output switch network through the first capacitor; and the first end of the second inductor is connected with the first end of the secondary side of the transformer module through the resonance switching control unit, and the second end of the second inductor is connected with the second end of the secondary side of the transformer module.
5. The single-stage high-frequency isolated bidirectional direct current converter according to claim 4, wherein the resonant switching control unit comprises a first resonant switch connected in parallel with the first inductor and a second resonant switch connected in series with the second inductor.
6. The single-stage high-frequency isolated bidirectional DC converter according to claim 5, wherein the boost energy storage module comprises a boost energy storage inductor connected between the input power source positive electrode and the first input terminal of the input switch network.
7. The single-stage high-frequency isolated bidirectional direct current converter according to claim 6, wherein the boost switching control unit comprises a boost switching switch connected in parallel across the boost energy storage inductor.
8. The single-stage high-frequency isolated bidirectional dc converter according to claim 7, wherein the boost energy storage module further comprises an input filter capacitor connected between the positive and negative poles of the output power source and an absorption unit connected between the first and second input terminals of the input switch network.
9. The single-stage high-frequency isolated bidirectional dc converter according to claim 8, wherein the input switch network and the output switch network comprise a full-bridge switch tube network or a half-bridge switch tube network, the absorption unit comprises an absorption diode, an absorption capacitor, and an absorption resistor, an anode of the absorption diode is connected to the first input terminal of the input switch network, a cathode of the absorption diode is connected to the second input terminal of the input switch network through the absorption capacitor, and the absorption resistor is connected in parallel to the absorption diode or the absorption capacitor.
10. A grid-connected energy storage system comprising a battery module, a photovoltaic module, a DC/DC module, a DC filter module, a DC/AC module, an AC filter module, a relay, a load, a grid module and the single-stage high-frequency isolated bidirectional DC converter according to any one of claims 1 to 9, wherein the photovoltaic module is connected to the DC filter module via the DC/DC module, the battery module is connected to the DC filter module via the single-stage high-frequency isolated bidirectional DC converter, and the DC filter module is further connected to a load or a grid module via the DC/AC module, the AC filter module, the relay in turn.
CN201911251918.2A 2019-12-09 2019-12-09 Single-stage high-frequency isolated bidirectional direct-current converter and grid-connected energy storage system Pending CN110957922A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111660844A (en) * 2020-06-10 2020-09-15 中国矿业大学 Plug-in electric automobile three-phase integrates on-vehicle charging system
CN115021568A (en) * 2021-11-01 2022-09-06 昆明理工大学 Partial power MPPT (maximum power point tracking) isolation DC-DC converter topology and control method
CN115694203A (en) * 2022-11-17 2023-02-03 深圳市迪威电气有限公司 Direct-current isolated converter capable of bidirectional conversion and control method thereof
CN117811398A (en) * 2024-02-27 2024-04-02 深圳通业科技股份有限公司 High-frequency auxiliary converter and control method

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111660844A (en) * 2020-06-10 2020-09-15 中国矿业大学 Plug-in electric automobile three-phase integrates on-vehicle charging system
CN115021568A (en) * 2021-11-01 2022-09-06 昆明理工大学 Partial power MPPT (maximum power point tracking) isolation DC-DC converter topology and control method
CN115021568B (en) * 2021-11-01 2024-03-29 昆明理工大学 Partial power MPPT isolation DC-DC converter topology and control method
CN115694203A (en) * 2022-11-17 2023-02-03 深圳市迪威电气有限公司 Direct-current isolated converter capable of bidirectional conversion and control method thereof
CN115694203B (en) * 2022-11-17 2023-08-04 深圳市迪威电气有限公司 DC isolated converter capable of bidirectional conversion and control method thereof
CN117811398A (en) * 2024-02-27 2024-04-02 深圳通业科技股份有限公司 High-frequency auxiliary converter and control method
CN117811398B (en) * 2024-02-27 2024-05-17 深圳通业科技股份有限公司 Control method of high-frequency auxiliary converter

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