WO2021237503A1 - 三相cllc双向直流变换器及其控制方法 - Google Patents

三相cllc双向直流变换器及其控制方法 Download PDF

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Publication number
WO2021237503A1
WO2021237503A1 PCT/CN2020/092564 CN2020092564W WO2021237503A1 WO 2021237503 A1 WO2021237503 A1 WO 2021237503A1 CN 2020092564 W CN2020092564 W CN 2020092564W WO 2021237503 A1 WO2021237503 A1 WO 2021237503A1
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phase
bridge arm
voltage
resonant
primary
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PCT/CN2020/092564
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English (en)
French (fr)
Inventor
曹国恩
王一波
曹睿
王哲
赵勇
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中国科学院电工研究所
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Priority to US17/012,020 priority Critical patent/US11088625B1/en
Publication of WO2021237503A1 publication Critical patent/WO2021237503A1/zh

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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
    • 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
    • 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
    • H02M7/4815—Resonant converters
    • H02M7/4818—Resonant converters with means for adaptation of resonance frequency, e.g. by modification of capacitance or inductance of resonance circuits
    • 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

Definitions

  • the invention belongs to the technical field of DC converters, and specifically relates to a three-phase CLLC bidirectional DC converter and a control method thereof.
  • the bidirectional DC converter can change the direction of the input and output current while keeping the input and output voltage unchanged, and realize the two-way transmission of energy. It is a key device for DC voltage conversion and power control. With the rapid development of renewable energy distributed power generation systems and DC distribution network technologies, bidirectional DC converters suitable for high-voltage and high-power applications have become one of the important development directions and research hotspots in recent years.
  • the high-voltage side voltage can be as high as several kV to tens of kV. Due to the low breakdown voltage of conventional power switching devices, high-voltage DC power systems mostly use high-voltage side series and low-voltage Modular connection mode with side parallel connection. However, as the voltage continues to increase, the number of modules increases, which poses severe challenges to the efficiency, reliability and power density of the system.
  • the bidirectional converter in the above-mentioned system needs to meet many requirements such as high voltage transformation ratio and high power output.
  • the converter adopting the multi-level technology can not only realize the two-way transmission of energy, but also meet the requirements of high voltage and high power, and can further reduce the voltage stress of the power switch tube.
  • the number of power devices in the multilevel converter has risen sharply, the circuit topology is very complicated, and there are problems such as uneven voltage division of the capacitor and high voltage stress of the clamp tube.
  • the application in the DC converter brings great challenges.
  • the present invention provides a three-phase CLLC bidirectional DC converter, which includes high-voltage-side voltage-dividing capacitor modules connected in sequence, three-phase half-and-a-half Bridge series module, three-phase primary side resonant module, three-phase isolation transformer, three-phase secondary side resonant module, three-phase half-bridge parallel module, low-voltage side capacitor module;
  • the high-voltage side voltage dividing capacitor module is used to divide the high-voltage side voltage, smooth the high-voltage DC bus voltage, and absorb the high pulse current of the three-phase half-bridge series module;
  • the three-phase half-bridge series module is used to modulate the divided DC bus voltage into a high-frequency alternating square wave when energy is transferred from the high-voltage side to the low-voltage side.
  • the energy is transferred from the low-voltage side to the high-voltage side It is used to rectify the high frequency AC voltage delivered by the transformer into DC voltage;
  • the three-phase primary side resonant module cooperates with the three-phase secondary side resonant module to realize the soft switching of the switch tube;
  • the three-phase isolation transformer is used to realize electrical isolation between the primary side and the secondary side and realize energy transmission between the primary side and the secondary side;
  • the three-phase half-bridge parallel module is used to rectify the high-frequency AC voltage transferred from the transformer into a DC voltage when energy is transferred from the high-voltage side to the low-voltage side.
  • the energy is transferred from the low-voltage side to the high-voltage side, it is used for Modulate the low-voltage DC bus voltage into a high-frequency alternating square wave;
  • the low-voltage side capacitor module is used to smooth the low-voltage DC bus voltage and absorb the high pulse current of the three-phase half-bridge parallel module.
  • the high-voltage side voltage dividing capacitor module includes a voltage dividing capacitor C H1 , a voltage dividing capacitor C H2 , and a voltage dividing capacitor C H3 ;
  • the voltages of the voltage dividing capacitor C H1 , the voltage dividing capacitor C H2 , and the voltage dividing capacitor C H3 are all 1/3 of the high voltage side voltage.
  • the three-phase half-bridge series module includes a bridge arm S 1 , a bridge arm S 2 , and a bridge arm S 3 in series ; the bridge arm S 1 , bridge arm S 2 , and bridge arm S 3 Each includes two switch tubes connected in series;
  • the three-phase half-bridge parallel module includes a bridge arm P 1 , a bridge arm P 2 , and a bridge arm P 3 connected in parallel; the arms P 1 , bridge arms P 2 , and bridge arms P 3 are respectively Including 2 switch tubes connected in series;
  • the three-phase primary resonant module includes a-phase primary resonant cavity, b-phase primary resonant cavity, and c-phase primary resonant cavity;
  • the three-phase secondary side resonant module includes a-phase secondary side resonant cavity, b-phase secondary side resonant cavity, and c-phase secondary side resonant cavity;
  • the three-phase isolation transformer includes a three-phase primary winding and a three-phase secondary winding
  • Each phase of the three-phase primary winding and the three-phase secondary winding is coupled to each phase of the primary resonant module and the secondary resonant module;
  • the primary side resonant capacitor C rpa and the primary side resonant inductance L rpa are connected in series between T b1 and the midpoint of the bridge arm S 2
  • the primary side resonant capacitor C rpb and the primary side resonant inductance L rpb are connected in series between T c1 and the midpoint of the bridge arm S 3
  • T a2 and T b1 between the primary side series resonant inductor L rpb, T b2 and T c1 between the primary side series resonant inductor L rpc, T c2 and
  • the primary side resonant inductance L rpa is connected in series between
  • the secondary side resonant capacitor C rsa and the secondary side resonant inductance L rsa are connected in series between T b3 and the midpoint of the bridge arm P 2
  • the secondary side resonant capacitor C rsb and the secondary side resonant inductance L rsb are connected in series between T c3 and the midpoint of the bridge arm P 3
  • the secondary side resonant inductance L rsa is connected in
  • the energy transmission of the DC converter includes forward energy transmission and reverse energy transmission
  • the forward energy transmission is energy transmission from the high-voltage side to the low-voltage side
  • the reverse energy transfer is the transfer of energy from the low pressure side to the high pressure side.
  • the three-phase primary resonant module is symmetrical with the three-phase secondary resonant module.
  • the three-phase isolation transformer is a transformer using a magnetic integration method.
  • a three-phase CLLC bidirectional DC converter control method is proposed. Based on the above three-phase CLLC bidirectional DC converter, the method includes:
  • Step S10 the switch tube is set according to the energy transmission direction, if the energy transmission direction is forward, then skip to step S20; if the energy transmission direction is reverse, then skip to step S30;
  • Step S20 setting the two switching tubes of the bridge arm S 1 , the bridge arm S 2 , and the bridge arm S 3 to be complementary conduction and the duty cycle are both 50%, and the bridge arm S 1 , the bridge arm S 2 and the bridge arm are set
  • the driving sequence of S 3 differs by 120° in sequence; the switch tubes of bridge arm P 1 , bridge arm P 2 , and bridge arm P 3 are set to work in synchronous rectification mode or uncontrolled rectification mode, and step S40 is skipped;
  • Step S30 setting the two switching tubes of the bridge arm P 1 , the bridge arm P 2 , and the bridge arm P 3 to be complementary conduction and the duty cycle are both 50%, and set the bridge arm P 1 , the bridge arm P 2 , and the bridge arm
  • the driving sequence of P 3 differs by 120° in sequence; the switch tubes of bridge arm S 1 , bridge arm S 2 , and bridge arm S 3 are set to work in synchronous rectification mode or uncontrolled rectification mode, and step S50 is skipped;
  • Step S40, the bridge arm S 1 , the bridge arm S 2 , and the bridge arm S 3 respectively modulate the divided high-voltage side voltage into a high-frequency AC square wave, which is transmitted to the three-phase transformer through the primary side resonant module, and in the switching mode During the switching process, the primary side resonance module makes the bridge arm S 1 , bridge arm S 2 , and bridge arm S 3 realize soft switching.
  • the bridge arm P 1 , bridge arm P 2 , and bridge arm P 3 adjust the height of the secondary side of the three-phase transformer.
  • the frequency alternating voltage is rectified to direct current.
  • the secondary side resonant module makes all the switch tubes of the bridge arm P 1 , bridge arm P 2 and bridge arm P 3 realize soft switching, and the input voltage is transmitted from the high voltage side to the low voltage. Side, to achieve DC conversion from high voltage to low voltage;
  • Step S50, the bridge arm P 1 , the bridge arm P 2 , and the bridge arm P 3 respectively modulate the low-voltage side voltage into a high-frequency AC square wave, which is transmitted to the three-phase transformer through the secondary side resonant module.
  • the side resonance module makes the bridge arm P 1 , bridge arm P 2 , and bridge arm P 3 realize soft switching.
  • the bridge arm S 1 , bridge arm S 2 and bridge arm S 3 alternate the high frequency of the primary side of the three-phase transformer The voltage is rectified to direct current, and the rectified direct current voltage is superimposed in series through the high-voltage side voltage divider capacitor.
  • the primary side resonant module makes the bridge arm S 1 , bridge arm S 2 , and bridge arm S 3 switch all
  • the tube realizes soft switching, the input voltage is transmitted from the low-voltage side to the high-voltage side, and the DC conversion from low-voltage to high-voltage is realized.
  • the input voltage is divided into 3 parts on the high-voltage side through a voltage divider capacitor, each of which is 1/3 of the input voltage, so the high-voltage side switch tube (ie, clamp tube)
  • the high-voltage side switch tube ie, clamp tube
  • the voltage stress has also been reduced to 1/3, and the voltage stress of the low-voltage side switch tube is the same as that of the low-voltage side, which is suitable for high-voltage and high-power applications.
  • the three-phase CLLC bidirectional DC converter of the present invention is equipped with a primary side resonant circuit and a secondary side resonant circuit. While power is transmitted in both directions, it realizes the soft switching function in a wide voltage and wide load range, reducing The loss of the switch.
  • the three-phase CLLC bidirectional DC converter of the present invention effectively increases the current ripple on the high-voltage side and the low-voltage side through the interleaved parallel connection of the three-phase circuits, thereby reducing the filter capacitor and increasing the power density of the converter.
  • the high- and low-voltage windings of the three-phase isolation transformer are respectively connected in a star or delta shape to realize the natural current sharing of the low-voltage side current and the natural voltage sharing of the high-voltage side voltage of the converter.
  • the three-phase CLLC bidirectional DC converter of the present invention integrates three single-phase isolation transformers into one transformer through magnetic integration, thereby improving the power density of the transformer.
  • Figure 1 is a schematic diagram of the structure of a three-phase CLLC bidirectional DC converter of the present invention
  • FIG. 2 is a schematic diagram of the structure of a three-phase CLLC bidirectional DC converter with a primary side star type and a secondary side star type connection mode of an embodiment of the three-phase CLLC bidirectional DC converter of the present invention
  • FIG. 3 is a waveform diagram of main operating parameters of an embodiment of the three-phase CLLC bidirectional DC converter of the present invention during forward energy transmission;
  • FIG. 4 is a waveform diagram of main operating parameters of an embodiment of the three-phase CLLC bidirectional DC converter of the present invention during reverse energy transmission;
  • Fig. 5 is an equivalent circuit model of an embodiment of the three-phase CLLC bidirectional DC converter of the present invention.
  • FIG. 10 is a structural diagram of different connection modes of the three-phase transformer and the primary and secondary side resonant modules of an embodiment of the three-phase CLLC bidirectional DC converter of the present invention.
  • the three-phase CLLC bidirectional DC converter of the present invention includes a high-voltage side voltage dividing capacitor module, a three-phase half-bridge series module, a three-phase primary resonance module, a three-phase isolation transformer, and a three-phase pair connected in sequence.
  • the high-voltage side voltage dividing capacitor module is used to divide the high-voltage side voltage, smooth the high-voltage DC bus voltage, and absorb the high pulse current of the three-phase half-bridge series module;
  • the three-phase half-bridge series module is used to modulate the divided DC bus voltage into a high-frequency alternating square wave when energy is transferred from the high-voltage side to the low-voltage side.
  • the energy is transferred from the low-voltage side to the high-voltage side It is used to rectify the high frequency AC voltage delivered by the transformer into DC voltage;
  • the three-phase primary side resonant module cooperates with the three-phase secondary side resonant module to realize the soft switching of the switch tube;
  • the three-phase isolation transformer is used to realize electrical isolation between the primary side and the secondary side and realize energy transmission between the primary side and the secondary side;
  • the three-phase half-bridge parallel module is used to rectify the high-frequency AC voltage transferred from the transformer into a DC voltage when energy is transferred from the high-voltage side to the low-voltage side.
  • the energy is transferred from the low-voltage side to the high-voltage side, it is used for Modulate the low-voltage DC bus voltage into a high-frequency alternating square wave;
  • the low-voltage side capacitor module is used to smooth the low-voltage DC bus voltage and absorb the high pulse current of the three-phase half-bridge parallel module.
  • a three-phase CLLC bidirectional DC converter includes a high-voltage side voltage dividing capacitor module 1, a three-phase half-bridge series module 2, a three-phase primary resonance module 3, a three-phase isolation transformer 4, and a three-phase secondary resonance Module 5, three-phase half-bridge parallel module 6, low-voltage side capacitor module 7, detailed description of each module is as follows:
  • the energy transmission of the three-phase CLLC bidirectional DC converter includes forward energy transmission and reverse energy transmission:
  • the forward energy transmission is the energy transmission from the high-voltage side to the low-voltage side, that is, the high-voltage side input voltage V H , and the low-voltage side is connected to the low-voltage side load, and its voltage is V L ;
  • the reverse energy transmission is the energy transmission from the low-voltage side to the high-voltage side , That is, the low-voltage side input voltage V L , which is transmitted to the high-voltage side to connect to the high-voltage side load, and its voltage is V H.
  • a high-pressure side comprises a dividing capacitor dividing capacitor C H1, dividing capacitor C H2, dividing capacitor C H3, which are high side voltage V H of the third voltage, i.e., V H / 3, since the divided voltage
  • V H the third voltage
  • the capacitance is relatively large, and each voltage dividing capacitor can also be regarded as a voltage source with a voltage of V H /3.
  • the low-voltage side capacitor 7 is denoted as V L , and can also be regarded as a voltage source with a voltage of V L.
  • the three-phase half-bridge series module 2 includes a bridge arm S 1 , a bridge arm S 2 , and a bridge arm S 3 in series.
  • Each bridge arm includes two switch tubes connected in series.
  • the bridge arm S 1 includes switch tubes S H1 and SH2.
  • the bridge arm S 2 includes switching tubes SH3 and SH4
  • the bridge arm S 3 includes switching tubes SH5 and SH6 .
  • connection point of the switch tubes S H1 and S H2 is the midpoint of the bridge arm S 1
  • connection point of the switch tubes S H3 and S H4 is the midpoint of the bridge arm S 2
  • connection point of the switch tubes S H5 and S H6 is the midpoint of the bridge arm S 3
  • the three-phase half-bridge parallel module 6 includes a bridge arm P 1 , a bridge arm P 2 , and a bridge arm P 3 in parallel.
  • Each bridge arm includes two switch tubes connected in series, and the bridge arm P 1 includes switch tubes S L1 and S L2 , The bridge arm P 2 includes switching tubes S L3 and S L4 , and the bridge arm P 3 includes switching tubes S L5 and S L6 .
  • connection point of the switch tubes S L1 and S L2 is the midpoint of the bridge arm P 1
  • connection point of the switch tubes S L3 and S L4 is the midpoint of the bridge arm P 2
  • connection point of the switch tubes S L5 and S L6 is the midpoint of the bridge arm P 3
  • the three-phase primary resonant module 3 includes a-phase primary resonant cavity, b-phase primary resonant cavity, and c-phase primary resonant cavity:
  • the a-phase primary resonant cavity includes the primary resonant capacitor C rpa , the primary resonant inductance L rpa , and the excitation inductance L ma ;
  • the b-phase primary resonant cavity includes the primary resonant capacitor C rpb , the primary resonant inductance L rpb , and the excitation inductance L mb ;
  • the c-phase primary resonant cavity includes a primary resonant capacitor C rpc , a primary resonant inductance L rpc , and an excitation inductance L mc .
  • the three-phase secondary side resonant module 5 includes a-phase secondary side resonant cavity, b-phase secondary side resonant cavity, and c-phase secondary side resonant cavity:
  • the a-phase secondary resonant cavity includes the secondary resonant capacitor C rsa and the secondary resonant inductance L rsa ;
  • the b-phase secondary resonant cavity includes the secondary resonant capacitor C rsb and the secondary resonant inductance L rsb ;
  • the c-phase secondary resonant cavity includes the secondary The side resonant capacitor C rsc and the secondary side resonant inductance L rsc .
  • the three-phase isolation transformer 4 includes a-phase isolation transformer T a , b-phase isolation transformer T b , and c-phase isolation transformer T c .
  • the primary and secondary windings of the three-phase isolation transformer adopt delta connection.
  • Three-phase primary winding of isolation transformer 4 is isolated by a transformer T a, b-phase isolation transformer T b, c isolated from the primary winding of the transformer T c configuration, each of the primary winding first end and a second end including T x1 T x2 ;
  • the secondary winding of the three-phase isolation transformer 4 is composed of the secondary windings of the a-phase isolation transformer T a , the b-phase isolation transformer T b , and the c-phase isolation transformer T c .
  • the primary side resonant capacitor C rpa and the primary side resonant inductance L rpa are connected in series between T b1 and the midpoint of the bridge arm S 2
  • the primary side resonant capacitor C rpb and the primary side resonant inductance L rpb are connected in series between T c1 and the midpoint of the bridge arm S 3
  • T a2 and T b1 between the primary side series resonant inductor L rpb, T b2 and T c1 between the primary side series resonant inductor L rpc, T c2 and
  • the primary resonance inductance L rpa is connected in series between T a1 .
  • the secondary side resonant capacitor C rsa and the secondary side resonant inductance L rsa are connected in series between T b3 and the midpoint of the bridge arm P 2
  • the secondary side resonant capacitor C rsb and the secondary side resonant inductance L rsb are connected in series between T c3 and the midpoint of the bridge arm P 3
  • the secondary side resonant inductance L rsa is connected in series between T a3 .
  • the first-phase CLLC bidirectional DC conversion module includes: primary side bridge arm S 1 , primary side resonant inductor L rpa , primary side resonant capacitor C rpa , excitation inductance L ma , transformer T a , secondary side resonant capacitor C rsa , secondary side resonant inductance L rsa , secondary side bridge arm P 1 ;
  • the second-phase CLLC bidirectional DC conversion module includes: primary side bridge arm S 2 , primary side resonant inductor L rpb , primary side resonant capacitor C rpb , magnetizing inductance L mb , transformer T b , secondary side resonant capacitor C rsb , secondary side resonant inductance L rsb , secondary side bridge arm P 2 ;
  • the third-phase CLLC bidirectional DC conversion module includes: primary side bridge arm S 3 , primary side resonant inductance L rpc , Primary
  • the present invention can form a three-phase CLLC bidirectional DC converter with different topological structures according to the different connection modes of the primary and secondary windings of the three-phase transformer.
  • Figure 2 it is an embodiment of the three-phase CLLC bidirectional DC converter of the present invention.
  • the connection of the primary and secondary windings of the three-phase transformer can also be adjusted as needed.
  • the present invention is here I will not elaborate on them one by one.
  • control method of the three-phase CLLC bidirectional DC converter according to the second embodiment of the present invention is based on the above-mentioned three-phase CLLC bidirectional DC converter, and the method includes:
  • Step S10 the switch tube is set according to the energy transmission direction, if the energy transmission direction is forward, then skip to step S20; if the energy transmission direction is reverse, then skip to step S30;
  • Step S20 setting the two switching tubes of the bridge arm S 1 , the bridge arm S 2 , and the bridge arm S 3 to be complementary conduction and the duty cycle are both 50%, and the bridge arm S 1 , the bridge arm S 2 and the bridge arm are set
  • the driving sequence of S 3 differs by 120° in sequence; the switch tubes of bridge arm P 1 , bridge arm P 2 , and bridge arm P 3 are set to work in synchronous rectification mode or uncontrolled rectification mode, and step S40 is skipped;
  • Step S30 setting the two switching tubes of the bridge arm P 1 , the bridge arm P 2 , and the bridge arm P 3 to be complementary conduction and the duty cycle are both 50%, and set the bridge arm P 1 , the bridge arm P 2 , and the bridge arm
  • the driving sequence of P 3 differs by 120° in sequence; the switch tubes of bridge arm S 1 , bridge arm S 2 , and bridge arm S 3 are set to work in synchronous rectification mode or uncontrolled rectification mode, and step S50 is skipped;
  • Step S40, the bridge arm S 1 , the bridge arm S 2 , and the bridge arm S 3 respectively modulate the divided high-voltage side voltage into a high-frequency AC square wave, which is transmitted to the three-phase transformer through the primary side resonant module, and in the switching mode During the switching process, the primary side resonance module makes the bridge arm S 1 , bridge arm S 2 , and bridge arm S 3 realize soft switching.
  • the bridge arm P 1 , bridge arm P 2 , and bridge arm P 3 adjust the height of the secondary side of the three-phase transformer.
  • the frequency alternating voltage is rectified to direct current.
  • the secondary side resonant module makes all the switch tubes of the bridge arm P 1 , bridge arm P 2 and bridge arm P 3 realize soft switching, and the input voltage is transmitted from the high voltage side to the low voltage. Side, to achieve DC conversion from high voltage to low voltage;
  • Step S50, the bridge arm P 1 , the bridge arm P 2 , and the bridge arm P 3 respectively modulate the low-voltage side voltage into a high-frequency AC square wave, which is transmitted to the three-phase transformer through the secondary side resonant module.
  • the side resonance module makes the bridge arm P 1 , bridge arm P 2 , and bridge arm P 3 realize soft switching.
  • the bridge arm S 1 , bridge arm S 2 and bridge arm S 3 alternate the high frequency of the primary side of the three-phase transformer The voltage is rectified to direct current, and the rectified direct current voltage is superimposed in series through the high-voltage side voltage divider capacitor.
  • the primary side resonant module makes the bridge arm S 1 , bridge arm S 2 , and bridge arm S 3 switch all
  • the tube realizes soft switching, the input voltage is transmitted from the low-voltage side to the high-voltage side, and the DC conversion from low-voltage to high-voltage is realized.
  • the working condition of the converter is similar in the first half cycle and the second half cycle.
  • the first half cycle is taken as an example to analyze the circuit, where V H is the high voltage side voltage; V L is the low voltage Side voltage; i Lrpa , i Lrpb , i Lrpc are the primary side resonant currents of the three-phase isolation transformer a-phase, b-phase, and c-phase; i Lrsa , i Lrsb , i Lrsc are the three-phase isolation transformer a-phase, b-phase, c
  • the secondary side resonant currents of the phases, i Lma , i Lmb , and i Lmc are the excitation currents of the three-phase isolation transformer a-phase, b-phase, and c-phase, and V Lma , V Lmb , and V Lmc are the three-phase isolation transformer a-phase and
  • Equation (1) and (2) Define the first resonant frequency as fr1 and the second resonant frequency as fr2 , as shown in equations (1) and (2):
  • the dead time is a phase circuit.
  • the parasitic capacitances of the primary switches S H1 and S H2 are charged and discharged through the primary resonant current i Lrpa of phase a.
  • the drain-source voltage of S H2 resonates to 0 to achieve soft turn-off, and the drain-source of S H1
  • the voltage resonates to the bridge arm bus voltage V H /3, reaching the soft turn-on condition. Due to participating in this resonance process, the current i Lma of L ma first resonates and then rises in the opposite direction.
  • phase a is equivalent to the resonance between the parasitic capacitances of S L1 and S L2 after L rpa and L rsa are connected in series .
  • the resonance current i Lrsa makes S L1 and S L2 realize soft switching, then S L1 is turned on, and S L2 is turned off.
  • This action also changes the voltage applied to L ma , L mb and L mc , specifically: V Lma is changed from -nV L /3 It becomes nV L /3, V Lmb changes from -nV L /3 to -nV L ⁇ 2/3, and V Lmc changes from nV L ⁇ 2/3 to nV L /3.
  • S H1 is applied to the gate turn-on signal, S H1 to achieve soft switching.
  • i Lrpa first resonates to 0, and then continues to resonate upward in the reverse direction.
  • V L clamps the voltage on the magnetizing inductance, so i Lma and i Lmc increase linearly, and i Lmb continues to decrease linearly.
  • the c-phase primary resonant current i Lrpc at time t 1 and the c-phase excitation current i Lmc equal, the c-phase is equivalent to L rpc after L mc and in parallel with the series L rsc and L5 of the S, S parasitic capacitance between the resonance L6, so that the resonant current i Lrsc S S L6 and L5 of soft switching, off after L5 of S, S L6 opened, L rsc Continue to resonate in series with C rsc.
  • the secondary current of phase b drops to zero due to the resonance of L rsb and C rsb , so the primary resonant current i Lrpb of phase b is equal to the excitation current i Lmb of phase b at time t 4, and phase b is equivalent to L rpb and L mb and after the parallel series L rsb, and between S L3, S L4 and the parasitic capacitance of the resonance, the resonant current i Lrsb S L3, and S L4 enable soft switching, off after S L3, S L4 opened, L rsb and C rsb continue to resonate in series.
  • SH3 is turned off, which is the dead time of the b-phase circuit. Since L mb >> L rpb and L mb >> L rsb, at this time, b-phase equivalent circuit for the L rsb and L mb and after the parallel series L rpb, and H3 of resonance between the S and S and the parasitic capacitance H4 , resonant current i Lrpb H4, the drain of S - source voltage rises from zero to V H / 3, S H3 drain - source voltage drop of V H / 3 to zero, to achieve soft turn-off H4 S, S H3 of reverse The diode is turned on. Due to resonance, the resonance of V Lma and V Lmc decreases, and the resonance of V Lmb increases.
  • the three-phase half-bridge parallel unit works in diode rectification mode or synchronous rectification mode; during reverse energy transmission, the three-phase half-bridge series unit works in diode rectification mode or synchronous rectification mode. Due to the resonance effect of the resonant inductance and the parasitic capacitance of the switch tube, both the soft switching of the diode or the synchronous rectifier tube can be realized, so the switching loss can be reduced and the efficiency of the converter can be improved.
  • High voltage gain is one of the important characteristics of the three-phase CLLC bidirectional DC converter.
  • the fundamental wave equivalent method is adopted, and it is assumed that the converter is only related to the fundamental wave component when transmitting energy through the resonant network, and the converter is equivalent to a linear circuit for analysis.
  • FIG. 5 it is an equivalent circuit model of an embodiment of the three-phase CLLC bidirectional DC converter of the present invention, that is, FIG. 5 is the fundamental wave equivalent conversion circuit of FIG. Take a circuit as an example for analysis.
  • Figure 6 it is an equivalent circuit model of the a-phase circuit of an embodiment of the three-phase CLLC bidirectional DC converter of the present invention.
  • the ratio is n
  • Q takes the value 0.1, 0.2, 0.5 respectively , 0.8, 1, 1.5, 2, there is a fixed point, at this point, no matter how the Q value changes, the voltage gain of the converter remains unchanged, and the gain value is 1/3.
  • the gain characteristics of the converter are combined by Q, k, and m, and they are coupled to each other. In specific applications, it can be designed according to the converter gain range and output power range.
  • the gain of the CLLC bidirectional converter is related to the quality factor Q of the primary side under the purely resistive load condition.
  • the converter gain is 1 / M A.
  • the bidirectional voltage gain of the converter is both 1, and the forward and reverse characteristics are the same.
  • the value of the transformer gain M T is also different, as follows:
  • FIG. 10 it is a structural diagram of different connection modes of the three-phase transformer and the primary and secondary side resonant modules of an embodiment of the three-phase CLLC bidirectional DC converter of the present invention.
  • the winding connection includes winding delta connection and winding star connection.
  • the three-phase CLLC two-way DC converter and its control method provided in the above embodiments are illustrated only by the division of the above-mentioned functional modules.
  • the above-mentioned functions can be allocated to different types according to needs.
  • Functional modules are implemented, that is, the modules or steps in the embodiments of the present invention are further decomposed or combined.
  • the modules in the above embodiments can be combined into one module, or can be further divided into multiple sub-modules to complete all or the steps described above. Part of the function.
  • the names of the modules and steps involved in the embodiments of the present invention are only for distinguishing each module or step, and are not regarded as improper limitations on the present invention.

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Abstract

本发明属于直流变换器技术领域，具体涉及了一种三相CLLC双向直流变换器及其控制方法，旨在解决现有基于模块化的高压侧串联-低压侧并联结构模块数量多、可靠性差以及现有基于多电平技术的变换器电路拓扑复杂、电容分压不均、钳位管电压应力高的问题。本发明包括：高压侧分压电容模块包括3个分压电容；三相半桥串联/并联模块包括串联/并联的三个桥臂，每个桥臂包括串联的两个开关管；三相原边/副边谐振模块包括a、b、c三相原边/副边谐振腔；三相隔离变压器包括a、b、c三个单相变压器；低压侧电容模块。本发明通过分压电容进行高压侧电压分压，降低钳位管电压应力，并通过高频软开关技术降低开关损耗，提高变换器效率和功率密度。

Description

三相CLLC双向直流变换器及其控制方法 技术领域
本发明属于直流变换器技术领域，具体涉及了一种三相CLLC双向直流变换器及其控制方法。
背景技术
双向直流变换器可实现输入、输出电压不变的同时，改变输入、输出电流的方向，实现能量的双向传输，是直流电压变换和功率控制的关键设备。随着可再生能源分布式发电系统和直流配电网技术的快速发展，适用于高压大功率场合的双向直流变换器成为近年来的重要发展方向和研究热点之一。
在直流配电网和可再生能源直流发电系统中，高压侧电压可高达几kV到几十kV，由于常规功率开关器件的击穿电压较低，高电压直流电源系统多采用高压侧串联、低压侧并联的模块化连接方式。然而，随着电压的不断提高，模块数量增加，对系统的效率、可靠性和功率密度提出了严峻的挑战。为了提高直流电源系统的普适性和综合电气性能，上述系统中的双向变换器需满足电压变比高、大功率输出等诸多需求。
为了适应高电压大功率的运行要求，多电平技术在变换器拓扑中得到较广泛的应用。采用多电平技术的变换器既能实现能量的双向传输，又能满足高电压大功率的要求，还可进一步降低功率开关管的电压应力。然而，随着高压侧电压的升高，多电平变换器功率器件的数量急剧上升，电路拓扑十分复杂，且存在电容分压不均、钳位管电压应力高等问题，为其在高电压双向直流变换器中的应用带来极大挑战。
发明内容
为了解决现有技术中的上述问题，即现有基于模块化的高压侧串联-低压侧并联结构模块数量多、可靠性差以及现有基于多电平技术的变换器随高压侧电压升高电路拓扑复杂、电容分压不均、钳位管电压应力高的问题，本发明提供了一种三相CLLC双向直流变换器，该直流变换器包括顺次连接的高压侧分压电容模块、三相半桥串联模块、三相原边谐振模块、三相隔离变压器、三相副边谐振模块、三相半桥并联模块、低压侧电容模块；
所述高压侧分压电容模块，用于进行将高压侧的电压分压以及平滑高压直流母线电压并吸收所述三相半桥串联模块的高脉冲电流；
所述三相半桥串联模块，当能量从高压侧向低压侧传递时，用于将分压后的直流母线电压调制为高频交变的交流方波，当能量从低压侧向高压侧传递时，用于将变压器传递来的高频交流电压整流为直流电压；
所述三相原边谐振模块，与所述三相副边谐振模块配合实现开关管的软开关；
所述三相隔离变压器，用于实现原边与副边的电气隔离以及实现原边与副边的能量传输；
所述三相半桥并联模块，当能量从高压侧向低压侧传递时，用于将将变压器传递来的高频交流电压整流为直流电压，当能量从低压侧向高压侧传递时，用于将低压直流母线电压调制为高频交变的交流方波；
所述低压侧电容模块，用于平滑低压直流母线电压并吸收所述三相半桥并联模块的高脉冲电流。
在一些优选的实施例中，所述高压侧分压电容模块包括分压电容C H1、分压电容C H2、分压电容C H3；
所述分压电容C H1、分压电容C H2、分压电容C H3的电压均为高压侧电压的1/3。
在一些优选的实施例中，所述三相半桥串联模块包括串联的桥臂S 1、桥臂S 2、桥臂S 3；所述桥臂S 1、桥臂S 2、桥臂S 3分别包括串联的2个开关管；
以所述2个开关管的串联连接点作为其对应的桥臂中点，获得桥臂S 1中点
Figure PCTCN2020092564-appb-000001
桥臂S 2中点
Figure PCTCN2020092564-appb-000002
桥臂S 3中点
Figure PCTCN2020092564-appb-000003
在一些优选的实施例中，所述三相半桥并联模块包括并联的桥臂P 1、桥臂P 2、桥臂P 3；所述臂P 1、桥臂P 2、桥臂P 3分别包括串联的2个开关管；
以所述2个开关管的串联连接点作为其对应的桥臂中点，获得桥臂P 1中点
Figure PCTCN2020092564-appb-000004
桥臂P 2中点
Figure PCTCN2020092564-appb-000005
桥臂P 3中点
Figure PCTCN2020092564-appb-000006
在一些优选的实施例中，所述三相原边谐振模块包括a相原边谐振腔、b相原边谐振腔、c相原边谐振腔；
所述a相原边谐振腔、b相原边谐振腔、c相原边谐振腔分别包括原边谐振电容C rpx、原边谐振电感L rpx；其中，x＝a/b/c。
在一些优选的实施例中，所述三相副边谐振模块包括a相副边谐振腔、b相副边谐振腔、c相副边谐振腔；
所述a相副边谐振腔、b相副边谐振腔、c相副边谐振腔分别包括副边谐振电容C rsx、副边谐振电感L rsx；其中，x＝a/b/c。
在一些优选的实施例中，所述三相隔离变压器包括三相原边绕组、三相副边绕组；
所述三相原边绕组、三相副边绕组各相分别耦接所述原边谐振模块、副边谐振模块的各相；
所述三相原边绕组包括第一端T x1、第二端T x2，x＝a/b/c；T a1与所述桥臂S 1中点
Figure PCTCN2020092564-appb-000007
之间串联原边谐振电容C rpa、原边谐振电感L rpa，T b1与所述桥臂S 2中点
Figure PCTCN2020092564-appb-000008
之间串联原边谐振电容C rpb、原边谐振电感L rpb，T c1与所述桥臂S 3中点
Figure PCTCN2020092564-appb-000009
之间串联原边谐振电容C rpc、原边谐振电感L rpc；T a2与T b1之间串联原边谐振电感L rpb，T b2与T c1之间串联原边谐振电感L rpc，T c2与T a1之间串联原边谐振电感L rpa；
所述三相副边绕组包括第三端T x3、第四端T x4，x＝a/b/c；T a3与所述桥臂P 1中点
Figure PCTCN2020092564-appb-000010
之间串联副边谐振电容C rsa、副边谐振电感L rsa，T b3与所述桥臂P 2中点
Figure PCTCN2020092564-appb-000011
之间串联副边谐振电容C rsb、副边谐振电感L rsb，T c3与所述桥臂P 3中点
Figure PCTCN2020092564-appb-000012
之间串联副边谐振电容C rsc、副边谐振电感L rsc；T a4与T b3之间串联副边谐振电感L rsb，T b4与T c3之间串联副边谐振电感L rsc，T c4与T a3之间串联副边谐振电感L rsa。
在一些优选的实施例中，所述直流变换器的能量传输包括正向能量传输、反向能量传输；
所述正向能量传输为能量从高压侧传输到低压侧；
所述反向能量传输为能量从低压侧传输到高压侧。
在一些优选的实施例中，所述三相原边谐振模块与所述三相副边谐振模块的三相对称。
在一些优选的实施例中，所述三相隔离变压器为采用磁集成方式的变压器。
本发明的另一方面，提出了一种三相CLLC双向直流变换器控制方法，基于上述的三相CLLC双向直流变换器，该方法包括：
步骤S10，按照能量传输方向进行开关管的设置，若能量传输方向为正向，则跳转步骤S20；若能量传输方向为反向，则跳转步骤S30；
步骤S20，分别设置桥臂S 1、桥臂S 2、桥臂S 3的2个开关管互补导通、占空比均为50％，并设置桥臂S 1、桥臂S 2、桥臂S 3的驱动时序依 次相差120°；设置桥臂P 1、桥臂P 2、桥臂P 3的开关管工作在同步整流模式或不控整流模式，跳转步骤S40；
步骤S30，分别设置桥臂P 1、桥臂P 2、桥臂P 3的2个开关管互补导通、占空比均为50％，并设置桥臂P 1、桥臂P 2、桥臂P 3的驱动时序依次相差120°；设置桥臂S 1、桥臂S 2、桥臂S 3的开关管工作在同步整流模式或不控整流模式，跳转步骤S50；
步骤S40，桥臂S 1、桥臂S 2、桥臂S 3分别将分压后的高压侧电压调制为高频交流方波，经由原边谐振模块后传递到三相变压器，在开关模态切换过程中原边谐振模块使桥臂S 1、桥臂S 2、桥臂S 3所有开关管实现软开关，桥臂P 1、桥臂P 2、桥臂P 3将三相变压器副边的高频交变电压整流为直流，在原边开关模态切换过程中副边谐振模块使桥臂P 1、桥臂P 2、桥臂P 3所有开关管实现软开关，输入电压从高压侧传输至低压侧，实现高压到低压的直流变换；
步骤S50，桥臂P 1、桥臂P 2、桥臂P 3分别将低压侧电压调制为高频交流方波，经由副边谐振模块后传递到三相变压器，在开关模态切换过程中副边谐振模块使桥臂P 1、桥臂P 2、桥臂P 3所有开关管实现软开关，桥臂S 1、桥臂S 2、桥臂S 3将三相变压器原边的高频交变电压整流为直流，并经过高压侧分压电容将整流后的直流电压串联叠加，在副边开关模态切换过程中原边谐振模块使桥臂S 1、桥臂S 2、桥臂S 3所有开关管实现软开关，输入电压从低压侧传输至高压侧，实现低压到高压的直流变换。
本发明的有益效果：
(1)本发明的三相CLLC双向直流变换器，在高压侧通过分压电容将输入电压分成3份，每份为输入电压的1/3，因而高压侧开关管(即钳位管)的电压应力也降至了1/3，低压侧开关管的电压应力与低压侧电压相同，适用于高压大功率场合。
(2)本发明的三相CLLC双向直流变换器，设置了原边谐振电路和副边谐振电路，在功率双向传输的同时，实现了在宽电压和宽负载范围内的软开关功能，减小了开关的损耗。
(3)本发明的三相CLLC双向直流变换器，通过三相电路的交错并联，有效提高高压侧和低压侧的电流纹波，进而减小滤波电容，提高了变换器的功率密度。
(4)本发明的三相CLLC双向直流变换器，三相隔离变压器高、低压绕组分别通过星型或三角形连接，实现了变换器低压侧电流的自然均流和高压侧电压的自然均压。
(5)本发明的三相CLLC双向直流变换器，通过磁集成将三个单相隔离变压器集成到一个变压器中，提高了变压器的功率密度。
附图说明
通过阅读参照以下附图所作的对非限制性实施例所作的详细描述，本申请的其它特征、目的和优点将会变得更明显：
图1是本发明三相CLLC双向直流变换器的结构示意图；
图2是本发明三相CLLC双向直流变换器一种实施例的原边星型、副边星型连接方式的三相CLLC双向直流变换器结构示意图；
图3是本发明三相CLLC双向直流变换器一种实施例的正向能量传输时主要工作参数波形图；
图4是本发明三相CLLC双向直流变换器一种实施例的反向能量传输时主要工作参数波形图；
图5是本发明三相CLLC双向直流变换器一种实施例的等效电路模型；
图6是本发明三相CLLC双向直流变换器一种实施例的a相电路的等效电路模型；
图7是本发明三相CLLC双向直流变换器一种实施例的k＝6、m＝0.8时不同Q下的增益曲线；
图8是本发明三相CLLC双向直流变换器一种实施例的Q＝0.2、m＝0.8时不同k下的增益曲线；
图9是本发明三相CLLC双向直流变换器一种实施例的k＝6、Q＝0.2时不同m下的增益曲线；
图10是本发明三相CLLC双向直流变换器一种实施例的三相变压器与原、副边谐振模块不同连接方式的结构图。
具体实施方式
下面结合附图和实施例对本申请作进一步的详细说明。可以理解的是，此处所描述的具体实施例仅用于解释相关发明，而非对该发明的限定。另外还需要说明的是，为了便于描述，附图中仅示出了与有关发明相关的部分。
需要说明的是，在不冲突的情况下，本申请中的实施例及实施例中的特征可以相互组合。下面将参考附图并结合实施例来详细说明本申请。
本发明的一种三相CLLC双向直流变换器，该直流变换器包括顺次连接的高压侧分压电容模块、三相半桥串联模块、三相原边谐振模块、三相隔离变压器、三相副边谐振模块、三相半桥并联模块、低压侧电容模块；
所述高压侧分压电容模块，用于进行将高压侧的电压分压以及平滑高压直流母线电压并吸收所述三相半桥串联模块的高脉冲电流；
所述三相半桥串联模块，当能量从高压侧向低压侧传递时，用于将分压后的直流母线电压调制为高频交变的交流方波，当能量从低 压侧向高压侧传递时，用于将变压器传递来的高频交流电压整流为直流电压；
所述三相原边谐振模块，与所述三相副边谐振模块配合实现开关管的软开关；
所述三相隔离变压器，用于实现原边与副边的电气隔离以及实现原边与副边的能量传输；
所述三相半桥并联模块，当能量从高压侧向低压侧传递时，用于将将变压器传递来的高频交流电压整流为直流电压，当能量从低压侧向高压侧传递时，用于将低压直流母线电压调制为高频交变的交流方波；
所述低压侧电容模块，用于平滑低压直流母线电压并吸收所述三相半桥并联模块的高脉冲电流。
为了更清晰地对本发明三相CLLC双向直流变换器进行说明，下面结合图1对本发明实施例中各模块展开详述。
本发明一种实施例的三相CLLC双向直流变换器，包括高压侧分压电容模块1、三相半桥串联模块2、三相原边谐振模块3、三相隔离变压器4、三相副边谐振模块5、三相半桥并联模块6、低压侧电容模块7，各模块详细描述如下：
三相CLLC双向直流变换器的能量传输包括正向能量传输、反向能量传输：
正向能量传输为能量从高压侧传输到低压侧，即高压侧输入电压V H，传输至低压侧连接低压侧负载，其电压为V L；反向能量传输为能量从低压侧传输到高压侧，即低压侧输入电压V L，传输至高压侧连接高压侧负载，其电压为V H。
高压侧分压电容1包括分压电容C H1、分压电容C H2、分压电容C H3，其电压均为高压侧电压V H的1/3，即V H/3，由于分压电压的容值较大，各分压电容也可以分别看作电压为V H/3的电压源。
低压侧电容7记作V L，也可以看作电压为V L的电压源。
三相半桥串联模块2包括串联的桥臂S 1、桥臂S 2、桥臂S 3，每一个桥臂分别包括串联的2个开关管，桥臂S 1包括开关管S H1、S H2，桥臂S 2包括开关管S H3、S H4，桥臂S 3包括开关管S H5、S H6。
开关管S H1、S H2的连接点为桥臂S 1的中点
Figure PCTCN2020092564-appb-000013
同样，开关管S H3、S H4的连接点为桥臂S 2的中点
Figure PCTCN2020092564-appb-000014
开关管S H5、S H6的连接点为桥臂S 3的中点
Figure PCTCN2020092564-appb-000015
三相半桥并联模块6包括并联的桥臂P 1、桥臂P 2、桥臂P 3，每一个桥臂分别包括串联的2个开关管，桥臂P 1包括开关管S L1、S L2，桥臂P 2包括开关管S L3、S L4，桥臂P 3包括开关管S L5、S L6。
开关管S L1、S L2的连接点为桥臂P 1的中点
Figure PCTCN2020092564-appb-000016
同样，开关管S L3、S L4的连接点为桥臂P 2的中点
Figure PCTCN2020092564-appb-000017
开关管S L5、S L6的连接点为桥臂P 3的中点
Figure PCTCN2020092564-appb-000018
三相原边谐振模块3包括a相原边谐振腔、b相原边谐振腔、c相原边谐振腔：
a相原边谐振腔包括原边谐振电容C rpa、原边谐振电感L rpa、励磁电感L ma；b相原边谐振腔包括原边谐振电容C rpb、原边谐振电感L rpb、励磁电感L mb；c相原边谐振腔包括原边谐振电容C rpc、原边谐振电感L rpc、励磁电感L mc。
三相副边谐振模块5包括a相副边谐振腔、b相副边谐振腔、c相副边谐振腔：
a相副边谐振腔包括副边谐振电容C rsa、副边谐振电感L rsa；b相副边谐振腔包括副边谐振电容C rsb、副边谐振电感L rsb；c相副边谐振腔包括副边谐振电容C rsc、副边谐振电感L rsc。
三相隔离变压器4包括a相隔离变压器T a、b相隔离变压器T b、c相隔离变压器T c，三相隔离变压器的原、副边绕组均采用三角形连接方式。
三相隔离变压器4的原边绕组由a相隔离变压器T a、b相隔离变压器T b、c相隔离变压器T c的原边绕组构成，各原边绕组包括第一端T x1和第二端T x2；同样，三相隔离变压器4的副边绕组由a相隔离变压器T a、b相隔离变压器T b、c相隔离变压器T c的副边绕组构成，各原边绕组包括第三端T x3和第四端T x4；其中，x＝a/b/c。
T a1与所述桥臂S 1中点
Figure PCTCN2020092564-appb-000019
之间串联原边谐振电容C rpa、原边谐振电感L rpa，T b1与所述桥臂S 2中点
Figure PCTCN2020092564-appb-000020
之间串联原边谐振电容C rpb、原边谐振电感L rpb，T c1与所述桥臂S 3中点
Figure PCTCN2020092564-appb-000021
之间串联原边谐振电容C rpc、原边谐振电感L rpc；T a2与T b1之间串联原边谐振电感L rpb，T b2与T c1之间串联原边谐振电感L rpc，T c2与T a1之间串联原边谐振电感L rpa。
T a3与所述桥臂P 1中点
Figure PCTCN2020092564-appb-000022
之间串联副边谐振电容C rsa、副边谐振电感L rsa，T b3与所述桥臂P 2中点
Figure PCTCN2020092564-appb-000023
之间串联副边谐振电容C rsb、副边谐振电感L rsb，T c3与所述桥臂P 3中点
Figure PCTCN2020092564-appb-000024
之间串联副边谐振电容C rsc、副边谐振电感L rsc；T a4与T b3之间串联副边谐振电感L rsb，T b4与T c3之间串联副边谐振电感L rsc，T c4与T a3之间串联副边谐振电感L rsa。
根据上述连接关系，第一相CLLC双向直流变换模块包括：原边桥臂S 1、原边谐振电感L rpa、原边谐振电容C rpa、励磁电感L ma、变压器T a、副边谐振电容C rsa、副边谐振电感L rsa、副边桥臂P 1；第二相CLLC双向直流变换模块包括：原边桥臂S 2、原边谐振电感L rpb、原边谐振电容C rpb、励磁电感L mb、变压器T b、副边谐振电容C rsb、副边谐振电 感L rsb、副边桥臂P 2；第三相CLLC双向直流变换模块包括：原边桥臂S 3、原边谐振电感L rpc、原边谐振电容C rpc、励磁电感L mc、变压器Tc、副边谐振电容C rsc、副边谐振电感L rsc、副边桥臂P 3。
本发明可以根据三相变压器原、副边绕组的连接方式不同，形成不同拓扑结构的三相CLLC双向直流变换器，如图2所示，为本发明三相CLLC双向直流变换器一种实施例的原边星型、副边星型连接方式的三相CLLC双向直流变换器结构示意图，在其他实施例中，还可以根据需要调整三相变压器原、副边绕组的连接方式，本发明在此不一一详述。
本发明第二实施例的三相CLLC双向直流变换器控制方法，基于上述的三相CLLC双向直流变换器，该方法包括：
步骤S10，按照能量传输方向进行开关管的设置，若能量传输方向为正向，则跳转步骤S20；若能量传输方向为反向，则跳转步骤S30；
步骤S20，分别设置桥臂S 1、桥臂S 2、桥臂S 3的2个开关管互补导通、占空比均为50％，并设置桥臂S 1、桥臂S 2、桥臂S 3的驱动时序依次相差120°；设置桥臂P 1、桥臂P 2、桥臂P 3的开关管工作在同步整流模式或不控整流模式，跳转步骤S40；
步骤S30，分别设置桥臂P 1、桥臂P 2、桥臂P 3的2个开关管互补导通、占空比均为50％，并设置桥臂P 1、桥臂P 2、桥臂P 3的驱动时序依次相差120°；设置桥臂S 1、桥臂S 2、桥臂S 3的开关管工作在同步整流模式或不控整流模式，跳转步骤S50；
步骤S40，桥臂S 1、桥臂S 2、桥臂S 3分别将分压后的高压侧电压调制为高频交流方波，经由原边谐振模块后传递到三相变压器，在开关模态切换过程中原边谐振模块使桥臂S 1、桥臂S 2、桥臂S 3所有开关管实现软开关，桥臂P 1、桥臂P 2、桥臂P 3将三相变压器副边的高频交变电压整流为直流，在原边开关模态切换过程中副边谐振模块使桥臂P 1、 桥臂P 2、桥臂P 3所有开关管实现软开关，输入电压从高压侧传输至低压侧，实现高压到低压的直流变换；
步骤S50，桥臂P 1、桥臂P 2、桥臂P 3分别将低压侧电压调制为高频交流方波，经由副边谐振模块后传递到三相变压器，在开关模态切换过程中副边谐振模块使桥臂P 1、桥臂P 2、桥臂P 3所有开关管实现软开关，桥臂S 1、桥臂S 2、桥臂S 3将三相变压器原边的高频交变电压整流为直流，并经过高压侧分压电容将整流后的直流电压串联叠加，在副边开关模态切换过程中原边谐振模块使桥臂S 1、桥臂S 2、桥臂S 3所有开关管实现软开关，输入电压从低压侧传输至高压侧，实现低压到高压的直流变换。
如图3和图4所示，分别为本发明三相CLLC双向直流变换器一种实施例的正向能量传输和反向能量传输时主要工作参数波形图，结合附图1，根据开关频率f s与谐振频率f r之间的大小关系，变换器的工作模式分为三种：模式一，f s>f r；模式二，f s＝f r；模式三，f s<f r。
以模式一为例，在一个完整周期中，变换器的工作情况在前半周期与后半周期相似，这里以前半周期为例对电路进行分析，其中，V H为高压侧电压；V L为低压侧电压；i Lrpa、i Lrpb、i Lrpc为三相隔离变压器a相、b相、c相的原边谐振电流；i Lrsa、i Lrsb、i Lrsc为三相隔离变压器a相、b相、c相的副边谐振电流，i Lma、i Lmb、i Lmc为三相隔离变压器a相、b相、c相的励磁电流，V Lma、V Lmb、V Lmc为三相隔离变压器a相、b相、c相的励磁电压，V Crpa、V Crpb、V Crpc为a相、b相、c相原边谐振电容的电压。
为了简化分析，进行以下假设：
(1)所有开关管均为理想器件；
(2)所有电感、电容均为理想器件；
(3)高压侧和低压侧电容足够大，可以在一个开关周期内看作是电压源；
(4)励磁电感L ma＝L mb＝L mc＝L m，原边谐振电感L rpa＝L rpb＝L rpc＝L rp，原边谐振电容C rpa＝C rpb＝C rpc＝C rp，副边谐振电感L rsa＝L rsb＝L rsc＝L rs，副边谐振电容C rsa＝C rsb＝C rsc＝C rs。
定义第一谐振频率为f r1，第二谐振频率为f r2，如式(1)、式(2)所示：
Figure PCTCN2020092564-appb-000025
Figure PCTCN2020092564-appb-000026
正向能量传输时，变换器的具体工作原理分析如下：
工作模态一[t 0-t 1]：
在t0时刻之前，S H1、S H2、S H3和S H6关断，S H4和S H5开通，处于a相电路的死区时间内。在该死区时间内，通过a相原边谐振电流i Lrpa对原边开关管S H1和S H2寄生电容进行充放电，S H2的漏源电压谐振到0，实现软关断，S H1的漏源电压谐振到桥臂母线电压V H/3，达到软开通条件。由于参与此谐振过程，L ma的电流i Lma先谐振下降然后反向升高。
同时，在t0时刻之前，a相的副边电流在谐振到零之后，a相等效为L rpa与L rsa串联后与S L1、S L2的寄生电容之间的谐振，谐振电流i Lrsa使S L1和S L2实现软开关，之后S L1开通，S L2关断，这一动作也使施加在L ma、L mb和L mc上的电压发生改变，具体为：V Lma由-nV L/3变为nV L/3，V Lmb由-nV L/3变为-nV L×2/3，V Lmc由nV L×2/3变为nV L/3。
在t 0时刻，S H1门极施加开通信号，S H1实现软开通。在t 0时刻之后，由于L rpa与C rpa的谐振作用，i Lrpa先谐振到0，然后反向继续谐振上升。V L将励磁电感上的电压钳位，因此i Lma、i Lmc线性升高，i Lmb继续线性下降。
工作模态二[t 1-t 2]：
在t 1时刻，c相副边电流由于L rsc和C rsc的谐振作用下降到0，因此c相原边谐振电流i Lrpc在t 1时刻与c相励磁电流i Lmc相等，c相等效为L rpc与L mc并联之后与L rsc串联，然后与S L5、S L6的寄生电容之间谐振,谐振电流i Lrsc使S L5和S L6实现软开关，之后S L5关断，S L6开通，L rsc与C rsc继续串联谐振。同时，由于励磁电感L ma、L mb、L mc也参与谐振，使得各励磁电感的电压改变，具体为：在谐振过程中V Lma谐振上升、V Lmb和V Lmc谐振下降。
工作模态三[t 2-t 3]：
在t 2时刻，S H5关断，此时段为c相电路的死区时间。由于L mc>>L rpc且L mc>>L rsc，此时，c相电路等效为L rsc与L mc并联之后与L rpc串联，然后与S H5和S H6的寄生电容之间的谐振，谐振电流i Lrpc使S H5的漏-源电压由0上升到V H/3、S H6的漏-源电压由V H/3下降到0，S H5实现软关断，S H6的反向二极管导通。由于谐振的作用，V Lma谐振上升、V Lmb和V Lmc谐振下降。
S H5软关断之后，L rpc、L rsc、L mc与S H5和S H6寄生电容之间谐振过程结束，施加在L ma、L mb和L mc上的电压发生改变，具体为：V Lma由工作模态2的nV L/3变为nV L×2/3，V Lmb由-nV L×2/3变为-nV L/3，V Lmc由nV L/3变为-nV L/3。因此，i Lmc在谐振完成后开始线性下降。
工作模态四[t 3-t 4]：
在t 3时刻，S H6门极施加开通信号，S H6由于二极管的续流作用，因此实现软开通。在t 3时刻之后，a、b、c相电路的原边和副边谐振单元继续谐振，励磁电感由于副边开关电路的钳位不参与谐振，因此励磁电流线性变化。
工作模态五[t 4-t 5]：
在t 4时刻，b相副边电流由于L rsb和C rsb的谐振作用下降到0，因此b相原边谐振电流i Lrpb在t 4时刻与b相励磁电流i Lmb相等，b相 等效为L rpb与L mb并联之后与L rsb串联，然后与S L3、S L4的寄生电容之间的谐振，谐振电流i Lrsb使S L3和S L4实现软开关，之后S L3关断，S L4开通，L rsb和C rsb继续串联谐振。
工作模态六[t 5-t 6]：
在t 5时刻，S H3关断，此时段为b相电路的死区时间。由于L mb>>L rpb且L mb>>L rsb，此时，b相电路等效为L rsb与L mb并联之后与L rpb串联，然后与S H3和S H4的寄生电容之间的谐振，谐振电流i Lrpb使S H4的漏-源电压由0上升到V H/3、S H3的漏-源电压由V H/3下降到零，S H4实现软关断，S H3的反向二极管导通。由于谐振的作用，V Lma和V Lmc谐振下降、V Lmb谐振上升。
S H3软关断之后，L rpb、L rsb、L mb与S H3和S H4寄生电容之间谐振过程结束，施加在L ma、L mb和L mc上的电压发生改变，具体为：V Lma由工作模态4的nV L×2/3变为nV L×2/3，V Lmb由-nV L/3变为nV L/3，V Lmc由-nV L/3变为-nV L×2/3。因此，i Lmb在谐振完成后开始线性下降。
在t 6时刻，S H4开通，b相死区时间结束。
工作模态七[t 6-t 7]
在t 6时刻，S H3门极施加开通信号，S H3由于二极管的续流作用，因此实现软开通。在t 6时刻之后，与工作模态四相同，a、b、c相电路的原边和副边谐振单元继续谐振，励磁电流线性变化。
工作模态八[t 7-t 8]：
在t 7时刻，a相副边电流由于L rsa和C rsa的谐振作用下降到零，因此a相原边谐振电流i Lrpa在t 7时刻与a相励磁电流i Lma相等，a相等效为L rpa与L ma并联之后与L rsa串联，然后与S L1、S L2的寄生电容之间的谐振，谐振电流i Lrsa使S L1和S L2实现软开关，之后S L1关断，S L2开通，L rsa和C rsa继续串联谐振。工作模态八的等效电路如图2所示。
t 8时刻以后，S H1关断，电路开始进入a相电路的死区时间，变换器进入后半个周期，工作情况与上述前半个周期相似。
反向能量传输时，变换器的具体工作原理分析与上述正向能量传输相似，本发明在此不再一一详述。
由以上工作过程分析可知，通过谐振电感和开关管寄生电容的谐振，可以实现开关管的零电压(ZVS)开通，同时由于谐振电感和串联谐振电容的谐振，开关管关断时刻电流较小，可以近似实现开关管的ZVS关断。
在进行正向能量传输时，三相半桥并联单元工作在二极管整流模式或同步整流模式；反向能量传输时，三相半桥串联单元工作在二极管整流模式或同步整流模式。由于谐振电感和开关管寄生电容的谐振作用，均可实现二极管或同步整流管的软开关，因此可降低开关损耗，提高变换器的效率。
高电压增益是三相CLLC双向直流变换器的重要特性之一。本发明一个实施例中采用基波等效法，假定变换器通过谐振网络传输能量时只与基波分量有关，将变换器等效为线性电路来分析。如图5所示，为本发明三相CLLC双向直流变换器一种实施例的等效电路模型，即图5是图1的基波等效变换电路。以a电路为例进行分析，如图6所示，为本发明三相CLLC双向直流变换器一种实施例的a相电路的等效电路模型，设能量由高压侧向低压侧传输，变压器变比为n，副边谐振电感折算至原边的等效电感值为L′ rsa＝L rsa/n 2，副边谐振电容折算至原边的等效电容至为C′ rsa＝C rsa×n 2，折算到原边的等效负载R eqa＝24n 2R L/π 2，其中R L为低压侧的负载，则归一化频率值、原边特征阻抗、原边品质因数、励磁电感与谐振电感之比、原边漏感与副边漏感之比分别如式(3)、式(4)、式(5)、式(6)、式(7)所示：
Figure PCTCN2020092564-appb-000027
Figure PCTCN2020092564-appb-000028
Figure PCTCN2020092564-appb-000029
Figure PCTCN2020092564-appb-000030
Figure PCTCN2020092564-appb-000031
因而，通过基波分析法，电压增益如式(8)所示：
Figure PCTCN2020092564-appb-000032
其中，a＝2k+1，
Figure PCTCN2020092564-appb-000033
如图7、图8和图9所示，分别为本发明三相CLLC双向直流变换器一种实施例的k＝6、m＝0.8时不同Q下的增益曲线，Q＝0.2、m＝0.8时不同k下的增益曲线以及k＝6、Q＝0.2时不同m下的增益曲线，由图中可知：(1)当k＝6、m＝0.8，Q分别依次取值0.1、0.2、0.5、0.8、1、1.5、2时，存在一个固定的点，在这个点上无论Q值如何改变，变换器的电压增益保持不变，增益值为1/3。在其他点，随着Q值的增加，在同一频率下电压增益减小；(2)当Q＝0.2、m＝0.8，k分别依次取值2、3、5、8、10、15、20、30、50时，当谐振频率等于开关频率时，无论k值如何改变，变换器的电压增益保持不变，增益值为1/3，同时，随着k值增加，电压增益的最小值减小，增益曲线区域平稳；(3)当k＝6、Q＝0.2，m分别依次取值0.3、0.5、0.7、0.8、1、1.5、2、5时，在低频区域(图中归一化频率f n≈0.38)处，存在一个固定的点，在这个点上无论m值如何改变，变换器的电压增益保持不变，在其他点，随着m值的减小，电压增益的峰值逐渐增大，由于一般变换器的Q值较小、k值较大，所以当m<1时，电压增益随着m值的变化较大，当m>1时，电压增益曲线变化较小。
由以上分析可知，变换器的增益特性由Q、k、m共同作用，且相互之间耦合。在具体应用中，可根据变换器增益范围、输出功率范围来进行设计。
通过改变S n桥臂和P n桥臂的开关频率，即可改变变换器的电压增益。在纯阻性条件下，即开关频率等于谐振频率时，A相电压增益可简化为式(9)所示：
Figure PCTCN2020092564-appb-000034
由以上可知，当m≠1时，在纯阻性负载条件下CLLC双向变换器的增益与原边的品质因数Q是相关的，当m＝1时，CLLC双向变换器的增益在纯阻性负载条件下为1，与负载无关。
当能量由低压侧向高压侧传输时，变换器增益为1/M A。当m＝1时，M A＝1/M A＝1，即变换器双向电压增益都为1，其正反向特性相同。
考虑a、b、c三相变压器原、副边的不同连接方式，设其增益为M T。当能量从高压侧向低压侧传输时，本发明三相CLLC双向直流变换器的电压增益如式(10)所示：
Figure PCTCN2020092564-appb-000035
根据三相变压器原、副边绕组的连接方式不同，变压器增益M T的取值也不同，具体如下：
(1)原边绕组星型连接，副边绕组星型连接：M T＝1；
(2)原边绕组星型连接，副边绕组三角形连接，
Figure PCTCN2020092564-appb-000036
(3)原边绕组三角型连接，副边绕组三角形连接，M T＝1；
(4)原边绕组三角型连接，副边绕组星连接，
Figure PCTCN2020092564-appb-000037
如图10所示，为本发明三相CLLC双向直流变换器一种实施例的三相变压器与原、副边谐振模块不同连接方式的结构图，绕组连 接包括绕组三角形连接和绕组星型连接两种方式，变压器绕组与谐振模块连接包括4中三角形连接和4中星型连接共8种方式。
所属技术领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的系统的具体工作过程及有关说明，可以参考前述方法实施例中的对应过程，在此不再赘述。
需要说明的是，上述实施例提供的三相CLLC双向直流变换器及其控制方法，仅以上述各功能模块的划分进行举例说明，在实际应用中，可以根据需要而将上述功能分配由不同的功能模块来完成，即将本发明实施例中的模块或者步骤再分解或者组合，例如，上述实施例的模块可以合并为一个模块，也可以进一步拆分成多个子模块，以完成以上描述的全部或者部分功能。对于本发明实施例中涉及的模块、步骤的名称，仅仅是为了区分各个模块或者步骤，不视为对本发明的不当限定。
术语“第一”、“第二”等是用于区别类似的对象，而不是用于描述或表示特定的顺序或先后次序。
术语“包括”或者任何其它类似用语旨在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备/装置不仅包括那些要素，而且还包括没有明确列出的其它要素，或者还包括这些过程、方法、物品或者设备/装置所固有的要素。
至此，已经结合附图所示的优选实施方式描述了本发明的技术方案，但是，本领域技术人员容易理解的是，本发明的保护范围显然不局限于这些具体实施方式。在不偏离本发明的原理的前提下，本领域技术人员可以对相关技术特征作出等同的更改或替换，这些更改或替换之后的技术方案都将落入本发明的保护范围之内。

Claims (11)

  1. 一种三相CLLC双向直流变换器，其特征在于，该直流变换器包括顺次连接的高压侧分压电容模块、三相半桥串联模块、三相原边谐振模块、三相隔离变压器、三相副边谐振模块、三相半桥并联模块、低压侧电容模块；
    所述高压侧分压电容模块，用于进行将高压侧的电压分压以及平滑高压直流母线电压并吸收所述三相半桥串联模块的高脉冲电流；
    所述三相半桥串联模块，当能量从高压侧向低压侧传递时，用于将分压后的直流母线电压调制为高频交变的交流方波，当能量从低压侧向高压侧传递时，用于将变压器传递来的高频交流电压整流为直流电压；
    所述三相原边谐振模块，与所述三相副边谐振模块配合实现开关管的软开关；
    所述三相隔离变压器，用于实现原边与副边的电气隔离以及实现原边与副边的能量传输；
    所述三相半桥并联模块，当能量从高压侧向低压侧传递时，用于将将变压器传递来的高频交流电压整流为直流电压，当能量从低压侧向高压侧传递时，用于将低压直流母线电压调制为高频交变的交流方波；
    所述低压侧电容模块，用于平滑低压直流母线电压并吸收所述三相半桥并联模块的高脉冲电流。
  2. 根据权利要求1所述的三相CLLC双向直流变换器，其特征在于，所述高压侧分压电容模块包括分压电容C H1、分压电容C H2、分压电容C H3；
    所述分压电容C H1、分压电容C H2、分压电容C H3的电压均为高压侧电压的1/3。
  3. 根据权利要求2所述的三相CLLC双向直流变换器，其特征在于，所述三相半桥串联模块包括串联的桥臂S 1、桥臂S 2、桥臂S 3；所述桥臂S 1、桥臂S 2、桥臂S 3分别包括串联的2个开关管；
    以所述2个开关管的串联连接点作为其对应的桥臂中点，获得桥臂S 1中点
    Figure PCTCN2020092564-appb-100001
    桥臂S 2中点
    Figure PCTCN2020092564-appb-100002
    桥臂S 3中点
    Figure PCTCN2020092564-appb-100003
  4. 根据权利要求3所述的三相CLLC双向直流变换器，其特征在于，所述三相半桥并联模块包括并联的桥臂P 1、桥臂P 2、桥臂P 3；所述臂P 1、桥臂P 2、桥臂P 3分别包括串联的2个开关管；
    以所述2个开关管的串联连接点作为其对应的桥臂中点，获得桥臂P 1中点
    Figure PCTCN2020092564-appb-100004
    桥臂P 2中点
    Figure PCTCN2020092564-appb-100005
    桥臂P 3中点
    Figure PCTCN2020092564-appb-100006
  5. 根据权利要求4所述的三相CLLC双向直流变换器，其特征在于，所述三相原边谐振模块包括a相原边谐振腔、b相原边谐振腔、c相原边谐振腔；
    所述a相原边谐振腔、b相原边谐振腔、c相原边谐振腔分别包括原边谐振电容C rpx、原边谐振电感L rpx；其中，x＝a/b/c。
  6. 根据权利要求5所述的三相CLLC双向直流变换器，其特征在于，所述三相副边谐振模块包括a相副边谐振腔、b相副边谐振腔、c相副边谐振腔；
    所述a相副边谐振腔、b相副边谐振腔、c相副边谐振腔分别包括副边谐振电容C rsx、副边谐振电感L rsx；其中，x＝a/b/c。
  7. 根据权利要求6所述的三相CLLC双向直流变换器，其特征在于，所述三相隔离变压器包括三相原边绕组、三相副边绕组；
    所述三相原边绕组、三相副边绕组各相分别耦接所述原边谐振模块、副边谐振模块的各相；
    所述三相原边绕组包括第一端T x1、第二端T x2，x＝a/b/c；T a1与所述桥臂S 1中点
    Figure PCTCN2020092564-appb-100007
    之间串联原边谐振电容C rpa、原边谐振电感L rpa，T b1与所述桥臂S 2中点
    Figure PCTCN2020092564-appb-100008
    之间串联原边谐振电容C rpb、原边谐振电感L rpb，T c1与所述桥臂S 3中点
    Figure PCTCN2020092564-appb-100009
    之间串联原边谐振电容C rpc、原边谐振电感L rpc；T a2与T b1之间串联原边谐振电感L rpb，T b2与T c1之间串联原边谐振电感L rpc，T c2与T a1之间串联原边谐振电感L rpa；
    所述三相副边绕组包括第三端T x3、第四端T x4，x＝a/b/c；T a3与所述桥臂P 1中点
    Figure PCTCN2020092564-appb-100010
    之间串联副边谐振电容C rsa、副边谐振电感L rsa，T b3与所述桥臂P 2中点
    Figure PCTCN2020092564-appb-100011
    之间串联副边谐振电容C rsb、副边谐振电感L rsb，T c3与所述桥臂P 3中点
    Figure PCTCN2020092564-appb-100012
    之间串联副边谐振电容C rsc、副边谐振电感L rsc；T a4与T b3之间串联副边谐振电感L rsb，T b4与T c3之间串联副边谐振电感L rsc，T c4与T a3之间串联副边谐振电感L rsa。
  8. 根据权利要求1-7任一项所述的三相CLLC双向直流变换器，其特征在于，所述直流变换器的能量传输包括正向能量传输、反向能量传输；
    所述正向能量传输为能量从高压侧传输到低压侧；
    所述反向能量传输为能量从低压侧传输到高压侧。
  9. 根据权利要求1-7任一项所述的三相CLLC双向直流变换器，其特征在于，所述三相原边谐振模块与所述三相副边谐振模块的三相对称。
  10. 根据权利要求1-7任一项所述的三相CLLC双向直流变换器，其特征在于，所述三相隔离变压器为采用磁集成方式的变压器。
  11. 一种三相CLLC双向直流变换器控制方法，其特征在于，基于权利要求1-10任一项所述的三相CLLC双向直流变换器，该方法包括：
    步骤S10，按照能量传输方向进行开关管的设置，若能量传输方向为正向，则跳转步骤S20；若能量传输方向为反向，则跳转步骤S30；
    步骤S20，分别设置桥臂S 1、桥臂S 2、桥臂S 3的2个开关管互补导通、占空比均为50％，并设置桥臂S 1、桥臂S 2、桥臂S 3的驱动时序依次相差120°；设置桥臂P 1、桥臂P 2、桥臂P 3的开关管工作在同步整流模式或不控整流模式，跳转步骤S40；
    步骤S30，分别设置桥臂P 1、桥臂P 2、桥臂P 3的2个开关管互补导通、占空比均为50％，并设置桥臂P 1、桥臂P 2、桥臂P 3的驱动时序依次相差120°；设置桥臂S 1、桥臂S 2、桥臂S 3的开关管工作在同步整流模式或不控整流模式，跳转步骤S50；
    步骤S40，桥臂S 1、桥臂S 2、桥臂S 3分别将分压后的高压侧电压调制为高频交流方波，经由原边谐振模块后传递到三相变压器，在开关模态切换过程中原边谐振模块使桥臂S 1、桥臂S 2、桥臂S 3所有开关管实现软开关，桥臂P 1、桥臂P 2、桥臂P 3将三相变压器副边的高频交变电压整流为直流，在原边开关模态切换过程中副边谐振模块使桥臂P 1、桥臂P 2、桥臂P 3所有开关管实现软开关，输入电压从高压侧传输至低压侧，实现高压到低压的直流变换；
    步骤S50，桥臂P 1、桥臂P 2、桥臂P 3分别将低压侧电压调制为高频交流方波，经由副边谐振模块后传递到三相变压器，在开关模态切换过程中副边谐振模块使桥臂P 1、桥臂P 2、桥臂P 3所有开关管实现软开关，桥臂S 1、桥臂S 2、桥臂S 3将三相变压器原边的高频交变电压整流为直流，并经过高压侧分压电容将整流后的直流电压串联叠加，在副边开关模态切换过程中原边谐振模块使桥臂S 1、桥臂S 2、桥臂S 3所有开关管实现软开关，输入电压从低压侧传输至高压侧，实现低压到高压的直流变换。
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