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CN116865567A - Three-level hybrid isolation DC-DC converter - Google Patents

Three-level hybrid isolation DC-DC converter Download PDF

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Publication number
CN116865567A
CN116865567A CN202310539761.3A CN202310539761A CN116865567A CN 116865567 A CN116865567 A CN 116865567A CN 202310539761 A CN202310539761 A CN 202310539761A CN 116865567 A CN116865567 A CN 116865567A
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CN
China
Prior art keywords
level
bridge
topology
isolated
full
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Pending
Application number
CN202310539761.3A
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Chinese (zh)
Inventor
刘才丰
邹旭东
朱东海
康勇
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Huazhong University of Science and Technology
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Huazhong University of Science and Technology
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Priority to CN202310539761.3A priority Critical patent/CN116865567A/en
Publication of CN116865567A publication Critical patent/CN116865567A/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
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H02M1/0054—Transistor switching losses
    • H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
    • 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
    • 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

本发明公开了一种三电平混合型隔离DC‑DC变换器，属于电力电子领域，包括：三电平单元、隔离单元和控制单元；三电平单元采用三电平半桥拓扑，隔离单元采用隔离全桥拓扑；三电平半桥拓扑的中点通过第一电感L1连接隔离全桥拓扑原边侧的全桥中点；三电平单元输入侧并联输入电容Cin，隔离单元输入侧、输出侧分别并联中间电容Cm、输出电容Co；控制单元用于在输入三电平单元的电压小于设定值时，以两电平调制方法控制三电平混合型隔离DC‑DC变换器；否则，以三电平调制方法控制三电平混合型隔离DC‑DC变换器。能够实现更宽的增益调节范围和软开关范围，适用于光伏系统、储能电池、电动汽车充电器等电压宽范围变化的场合。

The invention discloses a three-level hybrid isolated DC-DC converter, which belongs to the field of power electronics and includes: a three-level unit, an isolation unit and a control unit; the three-level unit adopts a three-level half-bridge topology, and the isolation unit An isolated full-bridge topology is adopted; the midpoint of the three-level half-bridge topology is connected to the full-bridge midpoint on the original side of the isolated full-bridge topology through the first inductor L 1 ; the input side of the three-level unit is connected in parallel with the input capacitor C in , and the isolation unit input The intermediate capacitor C m and the output capacitor C o are connected in parallel to the input side and the output side respectively; the control unit is used to control the three-level hybrid isolation DC-DC with a two-level modulation method when the voltage of the input three-level unit is less than the set value. converter; otherwise, a three-level hybrid isolated DC‑DC converter is controlled using a three-level modulation method. It can achieve a wider gain adjustment range and soft switching range, and is suitable for photovoltaic systems, energy storage batteries, electric vehicle chargers and other occasions where the voltage changes in a wide range.

Description

Three-level hybrid isolation DC-DC converter
Technical Field
The invention belongs to the field of power electronics, and particularly relates to a three-level hybrid isolation DC-DC converter.
Background
With the advent of carbon neutralization targets, the permeability of renewable energy power generation has increased year by year. Photovoltaic power generation is an important form of renewable energy power generation, and is greatly popularized. However, the output voltage of photovoltaic power generation is greatly affected by environmental factors such as illumination intensity and temperature, and the fluctuation range of the output voltage is large. Centralized photovoltaic power plants often employ a series connection of photovoltaic modules to increase the efficiency of power generation, however, the series connection of modules results in a higher peak voltage output, further expanding the range of output voltages. The peak value of the output voltage of the photovoltaic power station can reach 1700V or more, and the minimum output voltage can reach 250V. Voltages above 1700V have exceeded the withstand voltage of conventional silicon devices or silicon carbide devices.
Common isolated DC-DC converters have zero-voltage on and electrically isolated characteristics, such as double-active bridge converters. The traditional double-active-bridge converter has the defects of overlarge reflux power, losing zero-voltage turn-on characteristics and the like under the working condition of wide input voltage range, and the switching tube is insufficient to withstand high input voltage due to the design of two-level modulation. Therefore, how to design a multi-level isolation type converter with wide voltage range and high withstand voltage has very important research significance.
Disclosure of Invention
Aiming at the defects and improvement requirements of the prior art, the invention provides a three-level hybrid isolation DC-DC converter, which aims to solve the problem that the working performance of the existing isolation DC-DC converter is poor under the working conditions of high input voltage and wide input voltage range.
To achieve the above object, the present invention provides a three-level hybrid isolated DC-DC converter comprising: the device comprises a three-level unit, an isolation unit and a control unit; the three-level unit adopts a three-level half-bridge topology, and the isolation unit adopts an isolation full-bridge topology; the midpoint of the three-level half-bridge topology passes through a first inductor L 1 The full-bridge midpoint of the primary side of the isolation full-bridge topology is connected; the input side of the three-level unit is connected with an input capacitor C in parallel in The input side of the isolation unit is connected with an intermediate capacitor C in parallel m The output side of the isolation unit is connected with an output capacitor C in parallel o The method comprises the steps of carrying out a first treatment on the surface of the The control unit is used for controlling the voltage input into the three-level unit to be smaller than the set voltageWhen the value is fixed, the three-level hybrid isolation DC-DC converter is controlled by a two-level modulation method; otherwise, the three-level hybrid isolation DC-DC converter is controlled by a three-level modulation method.
Further, the three-level half-bridge topology comprises a first switching tube S connected in sequence 1 Second switch tube S 2 Third switch tube S 3 And a fourth switching tube S 4 The second switch tube S 2 And the third switching tube S 3 The connection point of the three-level half-bridge topology is the midpoint; the isolated full-bridge topology includes a primary side full-bridge, a secondary side full-bridge, and a transformer connecting the primary side full-bridge and the secondary side full-bridge.
Still further, the two-level modulation method includes: controlling the first switching tube S 1 And the fourth switching tube S 4 In a conducting state, control the second switching tube S 2 And the third switching tube S 3 Alternately conducting, and controlling the three-level hybrid isolation DC-DC converter to realize a DC-DC conversion function; control T s1 ＝T s2 Wherein T is s1 、T s2 The switching periods of the switching tubes are respectively the switching states of the switching tubes in the three-level half-bridge topology and the isolation full-bridge topology.
Still further, the three-level modulation method includes: controlling the first switching tube S 1 And the fourth switching tube S 4 Complementary conduction, controlling the second switching tube S 2 And the third switching tube S 3 Complementary conduction, controlling the first switching tube S 1 And the second switching tube S 2 The duty ratio of the three-level hybrid isolation DC-DC converter is the same, the phase shift duty ratio between the three-level hybrid isolation DC-DC converter and the phase shift duty ratio is 0.5, and the three-level hybrid isolation DC-DC converter is controlled to realize the DC-DC conversion function; control T s1 ＝2T s2 Wherein T is s1 、T s2 The switching periods of the switching tubes are respectively the switching states of the switching tubes in the three-level half-bridge topology and the isolation full-bridge topology.
Still further, the control unit is further configured to: controlling the primary side full bridge of the isolated full bridge topologyThe phase shift duty ratio between the three-level half-bridges is used for adjusting the first inductance L 1 Such that the freewheel current is equal to the soft-switch critical current.
Still further, the control unit is further configured to: and controlling the phase shift duty ratio between the primary side full bridge of the isolation full bridge topology and the secondary side full bridge of the isolation full bridge topology so that the output voltage of the secondary side full bridge of the isolation full bridge topology is equal to an output voltage instruction value.
Still further, the control unit is further configured to: controlling the duty cycle of the three-level half-bridge to adjust the intermediate capacitance C m And the intermediate voltage at two sides is matched with the output voltage of the secondary side full bridge of the isolation full bridge topology.
Further, the three-level half-bridge topology is diode clamping three-level topology, switching tube clamping three-level topology, flying capacitor three-level topology, clamping and flying capacitor mixed three-level topology or T-type three-level half-bridge topology.
Further, the isolated full-bridge topology is a dual active bridge topology, an LLC resonant topology, a CLLC resonant topology, a CLLLC resonant topology, an isolated series resonant topology, an isolated parallel resonant topology, a phase-shifted full-bridge topology, an isolated half-bridge topology, or a dual-pipe forward topology.
In general, through the above technical solutions conceived by the present invention, the following beneficial effects can be obtained:
(1) The structure of the isolation DC-DC converter is optimally designed, and a three-level structure is arranged on the input side of the isolation DC-DC converter to perform multi-level conversion, so that the peak input voltage of the converter is improved; furthermore, two different modulation methods are provided for different working conditions, so that the efficiency of the switching tube under the working condition of wide input voltage is optimized, extremely high DC-DC conversion precision can be maintained under the working condition of low input voltage, and the voltage applied to the two ends of the switching tube is reduced under the working condition of high input voltage, so that the switching tube is suitable for high-voltage occasions;
(2) The proposed sectional modulation method can realize soft switching in a full working condition range, and current ripple is not obviously increased along with the increase of voltage, so that the current stress of the switching tube is balanced in the full voltage range, and the switching tube type selection and circuit parameter design are facilitated;
(3) The soft switching of the switching tube is realized by utilizing the phase shift duty ratio between the three-level unit and the isolation unit, continuous frequency conversion operation is not needed, the stability is improved, the difficulty of electromagnetic compatibility design is reduced, a wider gain adjustment range and a wider soft switching range can be realized, and the method is suitable for voltage wide-range change occasions such as a photovoltaic system, an energy storage battery, an electric automobile charger and the like; in addition, the simplicity of the traditional control method is maintained, no complex algorithm or huge data amount lookup operation is needed, and the method is easy to realize on a digital controller.
Drawings
Fig. 1 is a topology diagram of a three-level hybrid isolated DC-DC converter according to an embodiment of the present invention;
fig. 2A, fig. 2B, fig. 2C, and fig. 2D are circuit diagrams of a flying capacitor type three-level topology, a diode clamping type three-level topology, a switching tube clamping type three-level topology, and a clamp and flying capacitor hybrid type three-level topology according to an embodiment of the present invention;
fig. 3A, fig. 3B, and fig. 3C are circuit diagrams of a dual active bridge topology, an LLC resonant topology, and a CLLLC resonant topology, respectively, provided in an embodiment of the invention;
FIG. 4 is a diagram of waveforms of operation when a two-level modulation method is used according to an embodiment of the present invention;
fig. 5A, fig. 5B, fig. 5C, fig. 5D, fig. 5E are circuit diagrams of stage I, stage II, stage III, stage IV, and stage V when the two-level modulation method is adopted according to the embodiments of the present invention;
FIG. 6 is a diagram of waveforms of operation when a three-level modulation method is used according to an embodiment of the present invention;
fig. 7A, fig. 7B, fig. 7C, fig. 7D, fig. 7E are circuit diagrams of stage I, stage II, stage III, stage IV, and stage V when the three-level modulation method is adopted according to the embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
In the present invention, the terms "first," "second," and the like in the description and in the drawings, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order.
Fig. 1 is a topology diagram of a three-level hybrid isolated DC-DC converter according to an embodiment of the present invention. Referring to fig. 1, a three-level hybrid isolated DC-DC converter according to the present embodiment will be described in detail with reference to fig. 2A to 7E.
Referring to fig. 1, the three-level hybrid isolated DC-DC converter includes: a three-level unit, an isolation unit and a control unit (not shown in the figure).
The three-level unit adopts a three-level half-bridge topology, and the isolation unit adopts an isolation full-bridge topology; the midpoint of the three-level half-bridge topology passes through the first inductor L 1 Connecting and isolating the full-bridge midpoint of the primary side of the full-bridge topology; input capacitor C connected in parallel at input side of three-level unit in Isolation unit input side parallel connection intermediate capacitor C m Parallel output capacitor C at output side of isolation unit o 。
The control unit is used for controlling the three-level hybrid isolation DC-DC converter by a two-level modulation method when the voltage input into the three-level unit is smaller than a set value; otherwise, the three-level hybrid isolation DC-DC converter is controlled by a three-level modulation method. The set value is designed according to the specific application scene.
According to an embodiment of the present invention, the three-level half-bridge topology is a diode clamp type three-level topology (circuit is shown in fig. 2B), a switching tube clamp type three-level topology (circuit is shown in fig. 2C), a flying capacitor type three-level topology (circuit is shown in fig. 2A), a clamp and flying capacitor hybrid type three-level topology (circuit is shown in fig. 2D), or a T type three-level half-bridge topology.
According to an embodiment of the present invention, the isolated full-bridge topology is a dual active-bridge topology (circuit is shown in fig. 3A), an LLC resonant topology (circuit is shown in fig. 3B), a CLLC resonant topology, a CLLLC resonant topology (circuit is shown in fig. 3C), an isolated series resonant topology, an isolated parallel resonant topology, a phase-shifted full-bridge topology, an isolated half-bridge topology, or a dual-pipe forward topology.
Referring to FIG. 1, the three-level cell has three external connection points, respectively connection point N 1 Connection point N 2 Connection point N 3 . Connection point N 1 And input capacitance C in Positive electrode connection of (C), connection point N 2 And input capacitance C in Is connected with the negative electrode of the connecting point N 3 Is connected with the isolation unit as an output point.
According to an embodiment of the invention, the three-level half-bridge topology comprises a first switching tube S connected in sequence 1 Second switch tube S 2 Third switch tube S 3 And a fourth switching tube S 4 Second switch tube S 2 And a third switching tube S 3 The junction point of (2) is the midpoint of the three-level half-bridge topology.
According to the positive pole of the input power supply and the first switch tube S 1 Drain electrode, first switch tube S 1 Source electrode, second switch tube S 2 Drain electrode, second switch tube S 2 Source, third switch tube S 3 Drain electrode, third switch tube S 3 Source, fourth switching tube S 4 Drain, fourth switching tube S 4 The source electrode and the negative electrode of the input power supply are sequentially connected. First switching tube S 1 And a second switching tube S 2 Formed as an upper half-bridge, a third switching tube S 3 And a fourth switching tube S 4 Formed as a lower half bridge. Connection point N 1 And bridge arm anodes of three-level half-bridge topology (i.e. S 1 Drain) connection; connection point N 2 And a bridge arm negative electrode of a three-level half-bridge topology (namely S 4 Source) connection; connection point N 3 Is the first inductance L 1 And a connection point of the isolation unit.
Referring to fig. 1, the isolation unit has five external connection points, respectively connection point P 1 Connection point P 2 Connection point P 3 Connection pointP 4 Connection point P 5 . Connection point P 1 And an intermediate capacitance C m Positive electrode connection of (a), connection point P 2 And a connection point N 3 Connection, connection point P 3 And an intermediate capacitance C m Is connected with the negative electrode of the connecting point P 4 And output capacitance C o Positive electrode connection of (a), connection point P 5 And output capacitance C o Is connected to the negative electrode of the battery.
According to an embodiment of the invention, the isolated full bridge topology comprises a primary side full bridge, a secondary side full bridge, and a transformer T connecting the primary side full bridge and the secondary side full bridge.
Connection point P 1 Is connected with the full bridge anode on the primary side, and is connected with a point P 2 Is connected with the midpoint of the full bridge on the primary side, and is connected with the point P 3 Is connected with the full bridge cathode on the primary side, and is connected with a point P 4 Is connected with the full bridge anode on the secondary side, and is connected with a point P 5 And the secondary side full-bridge cathode is connected.
The primary side full bridge comprises a fifth switch tube Q 1 Sixth switching tube Q 2 Seventh switch tube Q 3 Eighth switching tube Q 4 . Fifth switch tube Q 1 Source and sixth switching tube Q 2 The drain electrodes of the capacitors are connected to form a first half-bridge, an intermediate capacitor C m Two ends of a first half-bridge are connected in parallel, and the middle point of a bridge arm of the first half-bridge is connected with a first inductor L 1 And (5) connection. The middle point of the bridge arm of the first half bridge is also connected with the intermediate inductance L 2 Connected with the first winding n of the transformer T 1 Is connected with the homonymous end of the same. Seventh switch tube Q 3 Source of (d) and eighth switching tube Q 4 The drain electrode of the transformer T is connected with the middle point of the bridge arm of the second half bridge to form a first winding n of the transformer T 1 Is connected with the non-homonymous end of the (C). Fourth switching tube S 4 Source electrode of (A) sixth switching tube Q 2 Source of (d) and eighth switching tube Q 4 Is connected with the source electrode of the transistor; fifth switch tube Q 1 Drain electrode of (d) and seventh switching tube Q 3 Is connected to the drain of the transistor.
The secondary side full bridge comprises a ninth switch tube Q 5 Tenth switch tube Q 6 Eleventh switch tube Q 7 Twelfth switching tube Q 8 . Ninth switch tube Q 5 Source and tenth switch of (2)Tube Q 6 The drain electrodes of the first and second switches are connected to form a third half bridge, an eleventh switch tube Q 7 Source and twelfth switching tube Q 8 The drain connections of (2) form a fourth half bridge. The middle point of the bridge arm of the third half bridge and the second winding n of the transformer T 2 Is connected with the same name end of the transformer T, and the middle point of the bridge arm of the fourth half bridge is connected with the second winding n of the transformer T 2 Is connected with the non-homonymous end of the (C). Ninth switch tube Q 5 Drain of (d) and eleventh switch tube Q 7 Drain electrode connection of tenth switch tube Q 6 Source and twelfth switching tube Q 8 Is connected to the source of the (c).
Taking the flying capacitor type three-level topology shown in fig. 2A and the dual active bridge topology shown in fig. 3A as an example, the circuit configuration of the three-level cell and the isolation cell in the present embodiment is described.
Referring to FIG. 2A, the circuit of the three-level cell includes an upper half-bridge, a lower half-bridge, a first inductor L 1 Flying capacitor C f . Input capacitance C in The three-level half bridge is connected in parallel; flying capacitor C f The positive electrode of (a) is connected with the middle point of the upper half bridge, and the flying capacitor C f Is connected to the midpoint of the lower half-bridge.
Referring to fig. 3A, for the isolation unit, two ends of the secondary side full bridge are used as output ends to output the filter capacitor C in parallel o The method comprises the steps of carrying out a first treatment on the surface of the Two ends of the primary side full bridge are connected with an intermediate capacitor C in parallel m . The isolation unit further comprises a high frequency link comprising a second inductance L 2 And a transformer T. Midpoint of the first half-bridge of the primary side full-bridge and the second inductance L 2 Connected with the first winding n of the transformer T 1 Is connected with the homonymous end of the same.
In this embodiment, the control unit controls each switching tube by using a segment modulation method and/or a closed-loop control method. The segment modulation method refers to: when the per unit input voltage is small (for example, less than 1.66), a two-level modulation method is adopted; when the per unit input voltage is large (for example, greater than 1.66), a three-level modulation method is adopted.
According to an embodiment of the present invention, a two-level modulation method includes: control the first switching tube S 1 And a fourth switching tube S 4 In a conducting state, control the second switch tubeS 2 And a third switching tube S 3 Alternately conducting, and controlling the three-level hybrid isolation DC-DC converter to realize a DC-DC conversion function; control T s1 ＝T s2 Wherein T is s1 、T s2 The switching periods of the switching tubes are respectively the switching periods of the switching tubes with the switching states changed in the three-level half-bridge topology and the isolation full-bridge topology.
According to an embodiment of the present invention, a three-level modulation method includes: control the first switching tube S 1 And a fourth switching tube S 4 Complementary conduction and control of the second switching tube S 2 And a third switching tube S 3 Complementary conduction and control of the first switching tube S 1 And a second switching tube S 2 The duty ratio is the same, the phase shift duty ratio between the two is 0.5, and the three-level hybrid isolation DC-DC converter is controlled to realize the DC-DC conversion function; control T s1 ＝2T s2 Wherein T is s1 、T s2 The switching periods of the switching tubes are respectively the switching periods of the switching tubes with the switching states changed in the three-level half-bridge topology and the isolation full-bridge topology.
In three-level modulation, Q 1 And Q 2 Complementary conduction, Q 3 And Q 4 Complementary conduction, Q 5 And Q 6 Complementary conduction, Q 7 And Q 8 And a certain dead time is reserved between driving pulses of the complementary conduction switching tube.
The control unit is also used for: controlling the phase shift duty ratio between the isolated full bridge topology primary side full bridge and the three-level half bridge to adjust the first inductance L 1 Is the freewheel current i of (1) fw So that the freewheel current i fw Is equal to the critical current I of the soft switch ZVS 。
The control unit is also used for: controlling the phase shift duty ratio between the primary side full bridge and the secondary side full bridge of the isolated full bridge topology to enable the output voltage V of the secondary side full bridge of the isolated full bridge topology o Is equal to the output voltage command value V oref 。
The control unit is also used for: controlling the duty cycle of the three-level half-bridge to adjust the intermediate capacitance C m Intermediate voltage V of both sides m So that the intermediate voltage V m Full bridge with isolationOutput voltage V of topological secondary side full bridge o Matched, i.e. satisfy V m /V o ＝n 1 /n 2 。
In this embodiment, the duty cycle of the primary full bridge is Q 1 And Q 3 Duty cycle of (2); the duty cycle of the secondary side full bridge is Q 5 And Q 7 Duty cycle of (2); phase shift duty ratio D between primary side full bridge and three-level half bridge 1 Refers to Q 1 Is relative to the turn-on time of S 3 Phase shift duty cycle at turn-on time of (2); phase shift duty ratio D between secondary side full bridge and primary side full bridge 2 Refers to Q 5 Relative to Q 7 Phase shift duty cycle at turn-on time of (2); the phase shift duty cycle refers to the ratio of the difference in turn-on times to the switching period of the dual active bridge.
Taking the three-level unit shown in fig. 1 as a flying capacitor type three-level topology and the isolation unit as a double active bridge topology as an example, the working process diagram of the three-level hybrid type isolation DC-DC converter in the embodiment is described.
When operating in a two level modulation method, a typical operating waveform is shown in fig. 4, where there are 5 phases of operation within the switching period of a half of a dual active bridge. Because of symmetry, the boost and buck processes of the converter are similar, and this embodiment uses boost mode as an example for analysis. To simplify the analysis, it is assumed that the transformation ratio n of the transformer 1 /n 2 =n=1. The operation of each working phase is analyzed as follows.
Stage I [ t ] 0 -t 1 ]: as shown in fig. 5A, at t 0 Before the moment L 1 Is negative, L 2 Is positive. At time t 0 S of three-level half bridge 2 Turn off, S 3 Opening; q of primary side full bridge 2 And Q 3 Turned on with zero voltage switching (Zero Voltage Switch, ZVS), Q 1 And Q 4 Turning off; l (L) 1 Is approximately constant and passes through S 3 、S 4 And Q 2 Freewheeling; correspondingly, the Q of the secondary side full bridge 5 And Q 8 Turn on, Q 6 And Q 7 And (5) switching off. Over time, L 2 Is of the current linearity of (2)And (3) reducing. At this stage, L 2 The current of (2) is expressed as:
i L2 (t)＝i L2 (t 0 )-(V m +Vo/N)(t-t 0 )/L 2
stage II [ t ] 1 -t 2 ]: as shown in fig. 5B, at time t 1 The states of switching tubes in the three-level half bridge and the primary side full bridge are the same as phase I, L 2 Is reversed after the current is linearly reduced. Q (Q) 5 And Q 8 Turn off, this stage is Q 5 And Q 6 Q and 7 and Q 8 Is not exceeded. Secondary winding n 2 Is passed through Q 6 And Q 7 Is Q 6 And Q 7 The ZVS of (c) provides a condition.
Stage III [ t ] 2 -t 3 ]: as shown in fig. 5C, at time t 2 The switching tube states in the three-level half-bridge and the primary side full-bridge are the same as in phase II. Q (Q) 6 And Q 7 Turned on at ZVS. i.e L1 Keep approximately constant, L 2 The voltage across it is 0, i L2 Approximately constant. Primary side winding n 1 Through L 2 Transmitting power to secondary side winding n 2 。
Stage IV t 3 -t 4 ]: as shown in fig. 5D, at time t 3 The switching tube states in the primary side full bridge and the secondary side full bridge are the same as in phase III. S of three-level half bridge 3 Turn off, this stage is S 2 And S is 3 Is L 1 Is passed through S 2 Is S 2 The ZVS of (c) provides a condition.
Stage V t 4 -t 5 ]: as shown in fig. 5E, at time t 4 The switching tube states in the primary side full bridge and the secondary side full bridge are the same as in phase III. S of three-level half bridge 2 Turned on at ZVS. L (L) 1 Is at a voltage V in Linear energization, i L1 And linearly increases. L (L) 2 The voltage across it is 0, i L2 Approximately constant. At this stage, L 1 The current of (2) is expressed as:
i L1 (t)＝i L1 (t 4 )+V in (t-t 4 )/L 1
when operating in the three-level modulation method, a typical operating waveform is shown in fig. 6, where there are 5 phases of operation within the switching period of a half of the dual active bridge. Because of symmetry, the boost and buck processes of the converter are similar, and this embodiment uses boost mode as an example for analysis. To simplify the analysis, it is assumed that the transformation ratio n of the transformer 1 /n 2 =n=1. The operation of each stage is analyzed as follows.
Stage I [ t ] 0 -t 1 ]: as shown in fig. 7A, at t 0 Before the moment L 1 Is negative, L 2 Is positive. At time t 0 S of three-level half bridge 1 Turn off, S 2 Turn off, S 3 Opening, S 4 Opening; q of primary side full bridge 2 And Q 3 With zero voltage switch on, Q 1 And Q 4 Turning off; l (L) 1 Is approximately constant and passes through S 3 、S 4 And Q 2 Freewheeling; q of corresponding secondary side full bridge 5 And Q 8 Turn on, Q 6 And Q 7 And (5) switching off. Over time, L 2 Is reduced linearly. At this stage, L 2 The current of (2) is expressed as:
i L2 (t)＝i L2 (t 0 )-(V m +Vo/N)(t-t 0 )/L 2
stage II [ t ] 1 -t 2 ]: as shown in fig. 7B, at time t 1 The states of switching tubes in the three-level half bridge and the primary side full bridge are the same as phase I, L 2 Is reversed after the current is linearly reduced. Q (Q) 5 And Q 8 Turn off, this stage is Q 5 And Q 6 Q and 7 and Q 8 Is not exceeded. Secondary winding n 2 Is passed through Q 6 And Q 7 Is Q 6 And Q 7 The ZVS of (c) provides a condition.
Stage III [ t ] 2 -t 3 ]: as shown in fig. 7C, at time t 2 The switching tube states in the three-level half bridge and the primary side full bridge are the same as in the stage II。Q 6 And Q 7 Turned on at ZVS. i.e L1 Keep approximately constant, L 2 The voltage across it is 0, i L2 Approximately constant. Primary side winding n 1 Through L 2 Transmitting power to secondary side winding n 2 。
Stage IV t 3 -t 4 ]: as shown in fig. 7D, at time t 3 The switching tube states in the primary side full bridge and the secondary side full bridge are the same as in phase III. S of three-level half bridge 4 Turn off, this stage is S 1 And S is 4 Is L 1 Is passed through S 1 Is the free-wheeling of the body diode of S 1 The ZVS of (c) provides a condition.
Stage V t 4 -t 5 ]: as shown in fig. 7E, at time t 4 The switching tube states in the primary side full bridge and the secondary side full bridge are the same as in phase III. S of three-level half bridge 1 Turned on at ZVS. L (L) 1 Is at a voltage V in Linear energization, i L1 And linearly increases. L (L) 2 The voltage across it is 0, i L2 Approximately constant. At this stage, L 1 The current of (2) is expressed as:
i L1 (t)＝i L1 (t 4 )+V in (t-t 4 )/2L 1
comparing fig. 4 and fig. 6, it can be seen that when the input voltage is twice the original input voltage, by adopting the three-level modulation method, the current flowing through the switching tube can still be ensured to maintain the original change rule and magnitude, so that the converter has higher voltage-withstanding capability. When the input voltage is lower, a two-level modulation method is adopted, so that the conversion accuracy of the converter under the working condition of low input voltage is ensured.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims (9)

1.一种三电平混合型隔离DC-DC变换器，其特征在于，包括：三电平单元、隔离单元和控制单元；1. A three-level hybrid isolated DC-DC converter, characterized in that it includes: a three-level unit, an isolation unit and a control unit; 所述三电平单元采用三电平半桥拓扑，所述隔离单元采用隔离全桥拓扑；所述三电平半桥拓扑的中点通过第一电感L1连接所述隔离全桥拓扑原边侧的全桥中点；所述三电平单元输入侧并联输入电容Cin，所述隔离单元输入侧并联中间电容Cm，所述隔离单元输出侧并联输出电容Co；The three-level unit adopts a three-level half-bridge topology, and the isolation unit adopts an isolated full-bridge topology; the midpoint of the three-level half-bridge topology is connected to the primary side of the isolated full-bridge topology through a first inductor L1 The midpoint of the full bridge on the side; the input side of the three-level unit is connected in parallel with the input capacitor C in , the input side of the isolation unit is connected in parallel with the intermediate capacitor C m , and the output side of the isolation unit is connected in parallel with the output capacitor C o ; 所述控制单元用于在输入所述三电平单元的电压小于设定值时，以两电平调制方法控制所述三电平混合型隔离DC-DC变换器；否则，以三电平调制方法控制所述三电平混合型隔离DC-DC变换器。The control unit is used to control the three-level hybrid isolation DC-DC converter with a two-level modulation method when the voltage input to the three-level unit is less than a set value; otherwise, use a three-level modulation method. The method controls the three-level hybrid isolated DC-DC converter. 2.如权利要求1所述的三电平混合型隔离DC-DC变换器，其特征在于，所述三电平半桥拓扑包括依次连接的第一开关管S1、第二开关管S2、第三开关管S3和第四开关管S4，所述第二开关管S2和所述第三开关管S3的连接点为所述三电平半桥拓扑的中点；2. The three-level hybrid isolated DC-DC converter according to claim 1, wherein the three-level half-bridge topology includes a first switch S 1 and a second switch S 2 connected in sequence. , the third switching tube S 3 and the fourth switching tube S 4 , the connection point of the second switching tube S 2 and the third switching tube S 3 is the midpoint of the three-level half-bridge topology; 所述隔离全桥拓扑包括原边侧全桥、副边侧全桥，以及连接所述原边侧全桥和所述副边侧全桥的变压器。The isolated full-bridge topology includes a primary side full bridge, a secondary side full bridge, and a transformer connecting the primary side full bridge and the secondary side full bridge. 3.如权利要求2所述的三电平混合型隔离DC-DC变换器，其特征在于，所述两电平调制方法包括：3. The three-level hybrid isolated DC-DC converter according to claim 2, wherein the two-level modulation method includes: 控制所述第一开关管S1和所述第四开关管S4处于导通状态，控制所述第二开关管S2和所述第三开关管S3交替导通，控制所述三电平混合型隔离DC-DC变换器实现DC-DC变换功能；The first switching tube S 1 and the fourth switching tube S 4 are controlled to be in a conducting state, the second switching tube S 2 and the third switching tube S 3 are controlled to be alternately conducting, and the three power supplies are controlled to be in a conducting state. Flat hybrid isolated DC-DC converter realizes DC-DC conversion function; 控制Ts1＝Ts2，其中，Ts1、Ts2分别为所述三电平半桥拓扑中、所述隔离全桥拓扑中开关状态发生变化的开关管的开关周期。Control T s1 =T s2 , where T s1 and T s2 are respectively the switching periods of the switch tubes whose switching states change in the three-level half-bridge topology and the isolated full-bridge topology. 4.如权利要求2所述的三电平混合型隔离DC-DC变换器，其特征在于，所述三电平调制方法包括：4. The three-level hybrid isolated DC-DC converter according to claim 2, wherein the three-level modulation method includes: 控制所述第一开关管S1和所述第四开关管S4互补导通，控制所述第二开关管S2和所述第三开关管S3互补导通，控制所述第一开关管S1和所述第二开关管S2的占空比相同、且二者之间的移相占空比为0.5，控制所述三电平混合型隔离DC-DC变换器实现DC-DC变换功能；The first switching tube S 1 and the fourth switching tube S 4 are controlled to be in complementary conduction, the second switching tube S 2 and the third switching tube S 3 are controlled to be in complementary conduction, and the first switch is controlled to be in complementary conduction. The duty cycle of tube S 1 and the second switch tube S 2 is the same, and the phase shift duty cycle between them is 0.5, and the three-level hybrid isolation DC-DC converter is controlled to realize DC-DC. transformation function; 控制Ts1＝2Ts2，其中，Ts1、Ts2分别为所述三电平半桥拓扑中、所述隔离全桥拓扑中开关状态发生变化的开关管的开关周期。Control T s1 =2T s2 , where T s1 and T s2 are respectively the switching periods of the switch tubes whose switching states change in the three-level half-bridge topology and the isolated full-bridge topology. 5.如权利要求1-4任一项所述的三电平混合型隔离DC-DC变换器，其特征在于，所述控制单元还用于：控制所述隔离全桥拓扑原边侧全桥与所述三电平半桥之间的移相占空比，以调节所述第一电感L1的续流电流，使得所述续流电流等于软开关临界电流。5. The three-level hybrid isolated DC-DC converter according to any one of claims 1 to 4, characterized in that the control unit is also used to: control the original side full bridge of the isolated full-bridge topology. and the phase-shifted duty cycle between the three-level half bridge to adjust the freewheeling current of the first inductor L 1 so that the freewheeling current is equal to the soft switching critical current. 6.如权利要求1-4任一项所述的三电平混合型隔离DC-DC变换器，其特征在于，所述控制单元还用于：控制所述隔离全桥拓扑原边侧全桥与所述隔离全桥拓扑副边侧全桥之间的移相占空比，以令所述隔离全桥拓扑副边侧全桥的输出电压等于输出电压指令值。6. The three-level hybrid isolated DC-DC converter according to any one of claims 1 to 4, characterized in that the control unit is also used to: control the original side full bridge of the isolated full-bridge topology. The phase shift duty ratio between the secondary side full bridge of the isolated full bridge topology and the secondary side full bridge of the isolated full bridge topology is such that the output voltage of the secondary side full bridge of the isolated full bridge topology is equal to the output voltage command value. 7.如权利要求1-4任一项所述的三电平混合型隔离DC-DC变换器，其特征在于，所述控制单元还用于：控制所述三电平半桥的占空比，以调节所述中间电容Cm两侧的中间电压，使得所述中间电压与所述隔离全桥拓扑副边侧全桥的输出电压相匹配。7. The three-level hybrid isolated DC-DC converter according to any one of claims 1 to 4, characterized in that the control unit is also used to: control the duty cycle of the three-level half bridge. , to adjust the intermediate voltage on both sides of the intermediate capacitor C m , so that the intermediate voltage matches the output voltage of the secondary side full bridge of the isolated full-bridge topology. 8.如权利要求1所述的三电平混合型隔离DC-DC变换器，其特征在于，所述三电平半桥拓扑为二极管钳位型三电平拓扑、开关管钳位型三电平拓扑、飞跨电容型三电平拓扑、钳位与飞跨电容混合型三电平拓扑或T型三电平半桥拓扑。8. The three-level hybrid isolated DC-DC converter according to claim 1, wherein the three-level half-bridge topology is a diode clamped three-level topology or a switch tube clamped three-level topology. Flat topology, flying capacitor three-level topology, clamped and flying capacitor hybrid three-level topology or T-shaped three-level half-bridge topology. 9.如权利要求1所述的三电平混合型隔离DC-DC变换器，其特征在于，所述隔离全桥拓扑为双有源桥拓扑、LLC谐振型拓扑、CLLC谐振型拓扑、CLLLC谐振型拓扑、隔离串联谐振拓扑、隔离并联谐振型拓扑、移相全桥拓扑、隔离型半桥拓扑或双管正激拓扑。9. The three-level hybrid isolated DC-DC converter of claim 1, wherein the isolated full-bridge topology is a dual active bridge topology, LLC resonant topology, CLLC resonant topology, or CLLLC resonant topology. topology, isolated series resonant topology, isolated parallel resonant topology, phase-shifted full-bridge topology, isolated half-bridge topology or two-switch forward topology.
CN202310539761.3A 2023-05-11 2023-05-11 Three-level hybrid isolation DC-DC converter Pending CN116865567A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN119556137A (en) * 2025-01-20 2025-03-04 苏州新能先锋检测科技有限公司 A high-power high-frequency modular battery cluster charging and discharging test device and method
JP2025105602A (en) * 2023-12-28 2025-07-10 株式会社明電舎 Power Converter
CN120675420A (en) * 2025-08-21 2025-09-19 宁波亿储电气科技有限公司 Power supply device with adjustable output voltage and control method

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2025105602A (en) * 2023-12-28 2025-07-10 株式会社明電舎 Power Converter
CN119556137A (en) * 2025-01-20 2025-03-04 苏州新能先锋检测科技有限公司 A high-power high-frequency modular battery cluster charging and discharging test device and method
CN120675420A (en) * 2025-08-21 2025-09-19 宁波亿储电气科技有限公司 Power supply device with adjustable output voltage and control method

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