CN116915061A - Direct-current transformer with indirectly-connected input and application method thereof - Google Patents

Direct-current transformer with indirectly-connected input and application method thereof Download PDF

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Publication number
CN116915061A
CN116915061A CN202310844860.2A CN202310844860A CN116915061A CN 116915061 A CN116915061 A CN 116915061A CN 202310844860 A CN202310844860 A CN 202310844860A CN 116915061 A CN116915061 A CN 116915061A
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China
Prior art keywords
bridge
switching tube
full
series
direct current
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Pending
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CN202310844860.2A
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Chinese (zh)
Inventor
吴晋波
何智强
余波
宁光富
刘章华
谢国胜
姜利
李理
粟梅
李辉
肖潇
丁禹
李刚
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Hunan Electric Power Co Ltd
State Grid Hunan Electric Power Co Ltd
Original Assignee
State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Hunan Electric Power Co Ltd
State Grid Hunan Electric Power Co Ltd
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Priority to CN202310844860.2A priority Critical patent/CN116915061A/en
Publication of CN116915061A publication Critical patent/CN116915061A/en
Pending legal-status Critical Current

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Classifications

    • 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
    • H02M3/33573—Full-bridge at primary 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0006—Arrangements for supplying an adequate voltage to the control circuit of converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0041—Control circuits in which a clock signal is selectively enabled or disabled
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/14—Arrangements for reducing ripples from dc input or output
    • 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
    • H02M3/01—Resonant DC/DC converters
    • 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
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/06—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
    • H02M7/068—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode mounted on a 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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

Abstract

The application discloses a direct current transformer with indirectly connected input and an application method thereof, wherein the direct current transformer comprises N full-bridge modules, N high-frequency transformers, an LC resonant cavity and a rectification output circuit, the N full-bridge modules are connected in series, the midpoints of two bridge arms of the N full-bridge modules are respectively connected with the primary side of one high-frequency transformer as output ends, the secondary sides of the N high-frequency transformers are connected with the LC resonant cavity in series and then are connected with the input end of the rectification output circuit, and the output end of the rectification output circuit is the output end of the direct current transformer, so that all the full-bridge modules and the high-frequency transformers share the same LC resonant cavity and the rectification output circuit to realize natural current sharing. The application realizes the natural current sharing of the system output by sharing one LC resonant cavity and the output rectifying circuit, simultaneously greatly reduces the number of devices at the output end and saves the cost.

Description

Direct-current transformer with indirectly-connected input and application method thereof
Technical Field
The application belongs to the technical field of power electronics, and particularly relates to a direct current transformer with indirectly connected input and an application method thereof.
Background
Along with the urgent need of new energy system construction, the multi-converter module input serial output parallel combination system is used as a typical representative of the power electronic system integration technology, is a novel power supply structure with excellent performance and worth researching, and can meet the performance requirements of a better power range, voltage stress, current stress and the like of a power electronic device. The combination system of Input-Series Output-Parallel (ISOP) has been studied intensively by students, and various improvement strategies are proposed according to the problems.
The Chinese patent publication No. CN107017781A discloses an ISOP full-bridge direct-current converter controlled by asymmetric PWM and a control method thereof, wherein the ISOP full-bridge direct-current converter has a voltage regulating function, a full-bridge conversion circuit is adopted by a submodule of the ISOP full-bridge direct-current converter, the problem that a circuit is damaged due to concentrated capacitor breakdown discharge when a direct-current bus is in short-circuit fault is solved in an indirect input mode, the voltage stress of a system is reduced, and the stability and the guarantee of the system are improved. However, the voltage equalization cannot be guaranteed, and the voltage equalization cannot be guaranteed, so that additional voltage equalization control or current equalization control is needed, and the system control method is complex. The combined system needs a plurality of resonant cavities and output rectifying circuits, the number of devices is large, and the cost is increased.
Disclosure of Invention
The application aims to solve the technical problems: aiming at the problems of complex voltage equalizing and current equalizing control, more devices, higher cost and the like in the prior ISOP combined system converter scheme, the application provides the direct current transformer with indirectly connected input and the application method thereof after fully considering the factors such as cost, system reliability, loss and the like.
In order to solve the technical problems, the application adopts the following technical scheme:
an input indirect series DC transformer comprises N full-bridge modules, N high-frequency transformers, LC resonant cavities and a rectifying output circuitThe full-bridge module comprises two bridge arms and a filter capacitor which are connected in parallel, and the direct current input voltage V in The positive pole of the filter capacitor in the 1 st full-bridge module to the N-1 st full-bridge module is connected with the middle point of one bridge arm of the next full-bridge module, and the negative pole of the filter capacitor in the N full-bridge module is connected with the direct current input voltage V in The middle points of two bridge arms of the N full-bridge modules are used as output ends to be respectively connected with the primary side of one high-frequency transformer, the secondary sides of the N high-frequency transformers are connected with the LC resonant cavities in series and then are connected with the input end of the rectification output circuit, and the output end of the rectification output circuit is the output end of the direct-current transformer, so that all the full-bridge modules and the high-frequency transformers share the same LC resonant cavity and the rectification output circuit to realize natural current sharing of output.
Optionally, the LC resonant cavity is formed by a resonant inductance L r And a resonance capacitor C r And (3) connecting in series.
Optionally, the direct current input voltage V in A filter inductance L is also connected in series between the positive pole of the 1 st full bridge module and the middle point of one bridge arm b 。
Optionally, the rectifying output circuit includes two bridge arms formed by serially connecting diodes, and the two bridge arms are connected in parallel to form a rectifying bridge.
Optionally, an output capacitor C is connected in parallel with the output end of the rectifier bridge o 。
Optionally, the two parallel-connected bridge arms include a leading bridge arm and a lagging bridge arm, the leading bridge arm is formed by a first switch tube Q j1 And a second switching tube Q j2 Formed in series with a first switching tube Q j1 And a second switching tube Q j2 The middle joint between the two forms a bridge arm midpoint of the leading bridge arm; the lag bridge arm is formed by a third switch tube Q j3 And a fourth switching tube Q j4 Formed in series with a third switching tube Q j3 And a fourth switching tube Q j4 The intermediate junction between them forms the bridge arm midpoint of the lagging bridge arm.
Optionally, a first switching tube Q of the leading bridge arm j1 And a second switching tube Q j2 The control signals of the third switch tube Q of the hysteresis bridge arm are complementarily conducted and have different duty ratios j3 And a fourth switching tube Q j4 The control signals are complementarily conducted and have different duty ratios, and the second switch tube Q j2 And a fourth switching tube Q j4 Has a common duty cycle D on And duty ratio D on Total less than 0.5; second switch tube Q j2 And a fourth switching tube Q j4 At different switching frequencies f s With a constant on time of 0.5T r The method comprises the steps of carrying out a first treatment on the surface of the Fourth switching tube Q j4 Is delayed by the driving of the first switch tube Q j1 The driving time period of (1) was (0.5T) s -0.25T r ) The method comprises the steps of carrying out a first treatment on the surface of the Second switch tube Q j2 Is delayed by the driving of the third switch tube Q j3 The driving time period of (2) was also (0.5T s -0.25T r ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein T is r Is the resonance period of the LC resonant cavity, T s Is the switching period of the full bridge module.
Optionally, the duty cycle D on The following relationship is satisfied:
in the above, f s For the switching frequency of the full bridge module, f r Is the series resonant frequency of the LC resonant cavity and has f s <f r 。
In addition, the application also provides an application method of the direct current transformer with the input indirectly connected in series, which comprises the following steps: the LC resonant cavities connected in series on the secondary sides of the N high-frequency transformers are utilized to generate resonance effect, so that the first switch tube Q j1 And a third switching tube Q j3 Discharging parasitic capacitance of (1) to realize a first switching tube Q j1 And a third switching tube Q j3 The zero voltage is on.
Optionally, also comprises by controlling the switching frequency f s To adjust the second switching tube Q j2 And a fourth switching tube Q j4 Is 0.5T r In the switching period T s To make the second switch tube Q j2 And a fourth switching tubeQ j4 Duty ratio D of (2) on And correspondingly changes, thereby realizing the voltage regulation control of the direct current transformer.
Compared with the prior art, the application has the following advantages:
1. the direct current transformer with indirectly connected input comprises N full-bridge modules, N high-frequency transformers, an LC resonant cavity and a rectification output circuit, wherein the secondary sides of the N high-frequency transformers and the LC resonant cavity are connected in series and then are connected with the input end of the rectification output circuit, and the output end of the rectification output circuit is the output end of the direct current transformer, so that all the full-bridge modules and the high-frequency transformers share the same LC resonant cavity and the rectification output circuit to realize natural current sharing of output.
2. The application inputs all full-bridge modules of the direct-current transformer indirectly connected in series and the high-frequency transformer to share the same LC resonant cavity and rectifying output circuit, thereby reducing the number of devices, simplifying the system structure and lowering the application cost.
3. The secondary sides of the N high-frequency transformers are connected with the LC resonant cavities in series and then are connected with the input end of the rectification output circuit, so that resonance effect can be generated through the LC resonant cavities connected in series on the secondary sides of the high-frequency transformers, and zero voltage on the full-bridge module can be realized.
Drawings
Fig. 1 is a circuit topology of a dc transformer in an embodiment of the present application.
Fig. 2 is a waveform diagram of exemplary operation of the dc transformer in an embodiment of the present application.
Fig. 3 is an equivalent circuit diagram of a mode one of the dc transformer in the embodiment of the application.
Fig. 4 is an equivalent circuit diagram of a second mode of the dc transformer according to an embodiment of the present application.
Fig. 5 is an equivalent circuit diagram of a dc transformer mode three in an embodiment of the present application.
Fig. 6 is an equivalent circuit diagram of a dc transformer mode four in an embodiment of the present application.
Detailed Description
As shown in fig. 1, the input indirect series dc transformer of the present embodiment includes N full-bridge modules (1 # full-bridge module-N # full-bridge module)Bridge module), N high-frequency transformers (T 1 ～T N ) The full-bridge module comprises two bridge arms and a filter capacitor (C in1 ～C inN ) DC input voltage V in The positive pole of the filter capacitor in the 1 st full-bridge module to the N-1 st full-bridge module is connected with the middle point of one bridge arm of the next full-bridge module, and the negative pole of the filter capacitor in the N full-bridge module is connected with the direct current input voltage V in The middle points of two bridge arms of the N full-bridge modules are used as output ends to be respectively connected with the primary side of one high-frequency transformer, the secondary sides of the N high-frequency transformers are connected with the LC resonant cavities in series and then are connected with the input end of the rectification output circuit, and the output end of the rectification output circuit is the output end of the direct-current transformer, so that all the full-bridge modules and the high-frequency transformers share the same LC resonant cavity and the rectification output circuit to realize natural current sharing of output. The direct current transformer with indirectly connected input in series in the embodiment reduces the number of devices of the resonant circuit and the rectifying circuit by sharing one LC resonant cavity and the output rectifying circuit, reduces the application cost, realizes natural current sharing of output and simplifies the control mode of the system. In fig. 1, a filter capacitor (C in1 ～C inN ) The voltage of (2) is expressed as V d1 ～V dN Meanwhile, the voltage is also the direct current bus voltage of the full-bridge module; the input voltage of the N full bridge modules is v hv1 ～v hvN The method comprises the steps of carrying out a first treatment on the surface of the The output voltage of the N full bridge modules is v p1 ～v pN 。
In order to enhance the understanding of the present application, the following description will take the number of modules n=3 as an example with reference to the accompanying drawings. Namely: the DC transformer comprises 3 full-bridge modules, 3 high-frequency transformers and a DC input voltage V in The positive pole of the filter capacitor in the 1 st full-bridge module and the 2 nd full-bridge module are connected with the middle point of one bridge arm of the next full-bridge module, and the negative pole of the filter capacitor in the 3 rd full-bridge module is connected with the direct current input voltage V in The middle points of two bridge arms of 3 full-bridge modules are respectively used as output ends and are respectively connected with a high-frequency transformerThe secondary sides of the 3 high-frequency transformers are connected with the LC resonant cavities in series and then connected with the input end of the rectification output circuit.
As shown in fig. 1, the LC resonant cavity of the present embodiment is formed by a resonant inductance L r And a resonance capacitor C r And (3) connecting in series.
As shown in fig. 1, the dc input voltage V of the present embodiment in A filter inductance L is also connected in series between the positive pole of the 1 st full bridge module and the middle point of one bridge arm b 。
As shown in fig. 1, the rectifying output circuit of the present embodiment includes two bridge arms formed by serially connecting diodes, and the two bridge arms are connected in parallel to form a rectifying bridge. In this embodiment, an output capacitor C is connected in parallel with the output end of the rectifier bridge o . Referring to fig. 1, the first leg is formed by diode D 1 And D 2 Formed in series, the second leg being formed by a diode D 3 And D 4 Formed in series, the output of the rectifier bridge being connected to a load denoted R o The output voltage is V o 。
As shown in fig. 1, two parallel-connected bridge arms of the present embodiment include a leading bridge arm and a lagging bridge arm, the leading bridge arm is formed by a first switching tube Q j1 And a second switching tube Q j2 Formed in series with a first switching tube Q j1 And a second switching tube Q j2 The middle joint between the two forms a bridge arm midpoint of the leading bridge arm; the lag bridge arm is formed by a third switch tube Q j3 And a fourth switching tube Q j4 Formed in series with a third switching tube Q j3 And a fourth switching tube Q j4 The intermediate junction between them forms the bridge arm midpoint of the lagging bridge arm. The secondary sides of the N high-frequency transformers and the LC resonant cavities of the embodiment are connected in series and then connected with the input end of the rectifying output circuit, so that the LC resonant cavities connected in series on the secondary sides of the high-frequency transformers can generate resonance effect to enable the first switching tube Q j1 And a third switching tube Q j3 Is discharged by the parasitic capacitance of the first switch tube Q j1 And a third switching tube Q j3 The zero voltage is on. In FIG. 1, a first switching tube Q j1 The body diode of (2) is denoted as D j1 Second switch tube Q j2 The body diode of (2) is denoted as D j2 Third switch tube Q j3 The body diode of (2) is denoted as D j3 Fourth switching tube Q j4 The body diode of (2) is denoted as D j4 . In this embodiment, n=3, so the value range of j is 1,2,3. Referring to FIG. 1, taking a 1# full bridge module as an example, the leading bridge arm is formed by a first switching tube Q 11 And a second switching tube Q 12 The lag bridge arm is formed by a third switch tube Q 13 And a fourth switching tube Q 14 And the two are connected in series. Taking a 2# full-bridge module as an example, a leading bridge arm is formed by a first switch tube Q 21 And a second switching tube Q 22 The lag bridge arm is formed by a third switch tube Q 23 And a fourth switching tube Q 24 Serial formation, and so on.
In this embodiment, the first switching tube Q of the leading bridge arm j1 And a second switching tube Q j2 The control signals of the third switch tube Q of the hysteresis bridge arm are complementarily conducted and have different duty ratios j3 And a fourth switching tube Q j4 The control signals are complementarily conducted and have different duty ratios, and the second switch tube Q j2 And a fourth switching tube Q j4 Has a common duty cycle D on And duty ratio D on Total less than 0.5; second switch tube Q j2 And a fourth switching tube Q j4 At different switching frequencies f s With a constant on time of 0.5T r The method comprises the steps of carrying out a first treatment on the surface of the Fourth switching tube Q j4 Is delayed by the driving of the first switch tube Q j1 The driving time period of (1) was (0.5T) s -0.25T r ) The method comprises the steps of carrying out a first treatment on the surface of the Second switch tube Q j2 Is delayed by the driving of the third switch tube Q j3 The driving time period of (2) was also (0.5T s -0.25T r ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein T is r Is the resonance period of the LC resonant cavity, T s Is the switching period of the full bridge module.
In the present embodiment, the duty ratio D on The following relationship is satisfied:
in the above, f s For the switching frequency of the full bridge module, f r Is the series resonant frequency of the LC resonant cavity and has f s <f r 。
Referring to fig. 1, N high frequency transformers (T 1 ～T N ) The current on the primary side of the ratio is denoted as i, and is 1:n Lm1 ～i LmN The excitation inductance of the primary side is denoted as L m1 ～L mN 。
In addition, the embodiment also provides an application method of the direct current transformer with the input indirectly connected in series, which comprises the following steps: the LC resonant cavities connected in series on the secondary sides of the N high-frequency transformers are utilized to generate resonance effect, so that the first switch tube Q j1 And a third switching tube Q j3 Discharging parasitic capacitance of (1) to realize a first switching tube Q j1 And a third switching tube Q j3 The zero voltage is on.
The application method of the direct current transformer indirectly connected in series by the input of the embodiment further comprises the steps of controlling the switching frequency f s To adjust the second switching tube Q j2 And a fourth switching tube Q j4 Is 0.5T r In the switching period T s To make the second switch tube Q j2 And a fourth switching tube Q j4 Duty ratio D of (2) on And correspondingly changes, thereby realizing the voltage regulation control of the direct current transformer. When the number of modules n=3, the exemplary operating waveform corresponding to the direct current transformer indirectly connected in series is shown in fig. 2. With reference to FIGS. 3-6, it can be seen that t 0 ～t 4 For a complete switching cycle, a switching cycle includes four switching modes: t is t 0 ～t 2 For the first half of the switching period, t 2 ～t 4 For the second half of the switching period. The switching period t is analyzed below 0 ～t 4 Four modes of operation:
stage 1[t 0 ，t 1 ]: the current path in this mode is shown in FIG. 3, at t 0 Time of day, Q j2 Turn off, Q j1 Conducting. At resonance inductance L r Under the resonance action of Q j1 Conducting under zero voltage condition. At this stage, the voltage v across the transformer pj =0, input voltage V of each module hvj ＝V dj The full bridge module is at this pointStage is operated in the follow current state, primary current of the transformer passes through Q j3 And Q j1 Is freewheeling and the inductor current i Lb Through Q j1 Through the input capacitance C dj At this time C dj In a charged state, inductor current i Lb Is a linear decay from its maximum value, output capacitance C o And discharging to provide energy for the load.
Stage 2[t 1 ，t 2 ]: the current path in this mode is shown in FIG. 4, at t 1 Time of day, Q j3 Turn off, Q j4 Conducting. At this stage, input capacitance C dj In a discharge state, C dj To power a load. Input terminal voltage V of each module hvj ＝V dj Voltage v across transformer pj ＝V hvj . In comparison with phase 1, the input inductor voltage remains unchanged, while the inductor current i Lb From the phase 1 attenuated value, the same linear relationship is maintained to continue the attenuation. Output capacitor C o In a charged state, a partial resonant current flows.
Stage 3[t 2 ，t 3 ]: the current path in this mode is shown in FIG. 5, at t 2 Time of day, Q j4 Turn off, Q j3 Conducting. At L r Under the resonance action of Q j3 Can be turned on under zero voltage conditions. At this stage, the voltage v across the transformer pj =0, input voltage V of each module hvj ＝V dj The full bridge module operates in a freewheeling state at this stage, primary current i of the transformer p By conducting Q j3 And Q j1 The body diode freewheels in the opposite direction to the current in phase 1, C dj In a charged state. Inductor current i Lb Continuously attenuating the same linear relation and outputting the capacitance C o In a sustained discharge state, providing energy to the load.
Stage 4[t 3 ，t 4 ]: the current path in this mode is shown in FIG. 6, at t 3 Time of day, Q j1 Turn off, Q j2 Conducting. At this stage, C dj For supplying a load, primary current i of a transformer p And the stepSegment 2 is the opposite. Input terminal voltage V of each module hvj =0, voltage v across transformer pj ＝V d At this time C dj And (5) discharging. Input inductance L b Q conducted by each module j2 Directly connected in series with the input power supply, which is equivalent to the input power supply providing energy for the input filter inductor, the inductor L b The stored energy is continuously increased, the current i Lb A linear increase starts.
It can be seen that by controlling the switching frequency f s To adjust the duty cycle D on The voltage regulation control of the direct current transformer can be realized. In addition, the number of devices of the resonant circuit and the rectifying circuit is reduced by sharing one LC resonant cavity and one output rectifying circuit, so that the application cost is reduced, the natural current sharing of output is realized, and the control mode of the system is simplified; finally, zero-voltage switching-on of the primary side switching tube is realized through the LC series resonant cavity, and switching loss is reduced.
In summary, the primary side of the direct current transformer indirectly connected in series with the input of the embodiment is composed of an input filter inductor and N identical full-bridge modules, the secondary side of the direct current transformer comprises an LC resonant cavity and uncontrolled rectification, the primary side and the secondary side are connected through N high-frequency transformers, and the secondary sides of all the high-frequency transformers are directly connected in series. The on time of the bridge arm lower pipes of all the full-bridge modules is constant to be half of the resonance period, namely, the bridge arm lower pipes have the same duty ratio and are smaller than 0.5, and the voltage of the output end is controlled by controlling the magnitude of the switching frequency. The application adopts an asymmetric pulse width modulation control strategy, can improve the duty ratio modulation range of the switching tube, realizes zero voltage switching on of the switching tube, effectively reduces switching loss, improves the conversion efficiency of the converter, and reduces the number of devices at the output end by sharing one output rectifier bridge and one LC resonant cavity at the output end.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-readable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein. The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks. These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present application, and the protection scope of the present application is not limited to the above examples, and all technical solutions belonging to the concept of the present application belong to the protection scope of the present application. It should be noted that modifications and adaptations to the present application may occur to one skilled in the art without departing from the principles of the present application and are intended to be within the scope of the present application.

Claims (10)

1. The direct current transformer with indirectly connected input comprises N full-bridge modules, N high-frequency transformers, an LC resonant cavity and a rectifying output circuit, wherein the full-bridge modules comprise two bridge arms and a filter capacitor which are connected in parallel, and the direct current input voltage V in The positive pole of the filter capacitor in the 1 st full-bridge module to the N-1 st full-bridge module is connected with the middle point of one bridge arm of the next full-bridge module, and the negative pole of the filter capacitor in the N full-bridge module is connected with the direct current input voltage V in The middle points of two bridge arms of the N full-bridge modules are used as output ends to be respectively connected with the primary side of one high-frequency transformer, and the high-frequency transformer is characterized in that the secondary sides of the N high-frequency transformers and the LC resonant cavities are connected in series and then are connected with the input end of the rectification output circuit, the output end of the rectification output circuit is the output end of the direct-current transformer, so that all the full-bridge modules and the high-frequency transformers share the same LC resonant cavity and the rectification output circuit to realize natural current sharing of output.
2. The direct current transformer with indirectly connected input in series according to claim 1, wherein the LC resonant cavity is composed of a resonant inductance L r And a resonance capacitor C r And (3) connecting in series.
3. The direct current transformer with indirectly connected input in series according to claim 1, wherein the direct current input voltage V in A filter inductance L is also connected in series between the positive pole of the 1 st full bridge module and the middle point of one bridge arm b 。
4. The direct current transformer of claim 1, wherein the rectifying output circuit is an uncontrolled rectifying output circuit comprising two legs formed of diodes connected in series, and the two legs are connected in parallel to form a rectifying bridge.
5. The direct current transformer with indirectly connected input in series according to claim 4, wherein the wholeThe output end of the current bridge is connected in parallel with an output capacitor C o 。
6. The direct current transformer of claim 1, wherein the two parallel-connected legs comprise a leading leg and a lagging leg, the leading leg being formed by a first switching tube Q j1 And a second switching tube Q j2 Formed in series with a first switching tube Q j1 And a second switching tube Q j2 The middle joint between the two forms a bridge arm midpoint of the leading bridge arm; the lag bridge arm is formed by a third switch tube Q j3 And a fourth switching tube Q j4 Formed in series with a third switching tube Q j3 And a fourth switching tube Q j4 The intermediate junction between them forms the bridge arm midpoint of the lagging bridge arm.
7. The direct current transformer of claim 6, wherein the first switching tube Q of the leading leg j1 And a second switching tube Q j2 The control signals of the third switch tube Q of the hysteresis bridge arm are complementarily conducted and have different duty ratios j3 And a fourth switching tube Q j4 The control signals are complementarily conducted and have different duty ratios, and the second switch tube Q j2 And a fourth switching tube Q j4 Has a common duty cycle D on And duty ratio D on Total less than 0.5; second switch tube Q j2 And a fourth switching tube Q j4 At different switching frequencies f s With a constant on time of 0.5T r The method comprises the steps of carrying out a first treatment on the surface of the Fourth switching tube Q j4 Is delayed by the driving of the first switch tube Q j1 The driving time period of (1) was (0.5T) s -0.25T r ) The method comprises the steps of carrying out a first treatment on the surface of the Second switch tube Q j2 Is delayed by the driving of the third switch tube Q j3 The driving time period of (2) was also (0.5T s -0.25T r ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein T is r Is the resonance period of the LC resonant cavity, T s Is the switching period of the full bridge module.
8. The direct current transformer with indirectly connected input terminals according to claim 7, whereinThe duty ratio D on The following relationship is satisfied:
in the above, f s For the switching frequency of the full bridge module, f r Is the series resonant frequency of the LC resonant cavity and has f s <f r 。
9. A method of using a dc transformer having an input connected in series indirectly as claimed in any one of claims 6 to 8, comprising: the LC resonant cavities connected in series on the secondary sides of the N high-frequency transformers are utilized to generate resonance effect, so that the first switch tube Q j1 And a third switching tube Q j3 Discharging parasitic capacitance of (1) to realize a first switching tube Q j1 And a third switching tube Q j3 The zero voltage is on.
10. The method of claim 9, further comprising controlling the switching frequency f s To adjust the second switching tube Q j2 And a fourth switching tube Q j4 Is 0.5T r In the switching period T s To make the second switch tube Q j2 And a fourth switching tube Q j4 Duty ratio D of (2) on And correspondingly changes, thereby realizing the voltage regulation control of the direct current transformer.
CN202310844860.2A 2023-07-10 2023-07-10 Direct-current transformer with indirectly-connected input and application method thereof Pending CN116915061A (en)

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Application Number Priority Date Filing Date Title
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