CN112564497A - Three-phase LLC resonant DC converter - Google Patents

Three-phase LLC resonant DC converter Download PDF

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Publication number
CN112564497A
CN112564497A CN202011403939.4A CN202011403939A CN112564497A CN 112564497 A CN112564497 A CN 112564497A CN 202011403939 A CN202011403939 A CN 202011403939A CN 112564497 A CN112564497 A CN 112564497A
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China
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phase
circuit
transformer
primary
llc resonant
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Granted
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CN202011403939.4A
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CN112564497B (en
Inventor
庄加才
王涵宇
徐君
刘威
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Sungrow Power Supply Co Ltd
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Sungrow Power Supply Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33584—Bidirectional converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • 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
    • 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
    • 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 invention provides a three-phase LLC resonant direct-current converter, at least one side between the alternating current side of a primary circuit and the primary side of a transformer, at least two groups of adjacent phases in three groups of adjacent phases, and an interphase circuit is arranged between two phases of each group of adjacent phases, so that function multiplexing during power transmission can be realized; namely, compared with the prior art, the three-phase LLC resonant DC converter provided by the invention realizes three-phase conversion energy transmission by multiplexing two inter-phase circuits, and reduces the cost and the volume of the circuit.

Description

Three-phase LLC resonant DC converter
Technical Field
The invention relates to the technical field of power electronics, in particular to a three-phase LLC resonant direct-current converter.
Background
The three-phase LLC direct-current resonant converter has many advantages, such as simple circuit structure, large power, high efficiency, small capacitor ripple and the like, and therefore has very important application value in various occasions of energy transmission; in addition, the three-phase LLC direct-current resonant converter can realize soft switching in a full-load range, and has self-current-sharing capability when a transformer of the three-phase LLC direct-current resonant converter is in star connection.
The transformer adopts a star-connected three-phase LLC direct-current resonant converter, the structural schematic diagram of which is shown in fig. 1, and although the transformer has self-current-sharing capability, the number of internal elements is large, so that the circuit cost is high, and the size of the converter is large.
Disclosure of Invention
In view of this, embodiments of the present invention provide a three-phase LLC resonant dc converter to reduce circuit size and cost.
In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:
the invention provides a three-phase LLC resonant DC converter, comprising: a primary side circuit, a secondary side circuit and a transformer; wherein:
the primary side circuit and the secondary side circuit are both three-phase conversion circuits;
the alternating current side of the primary side circuit is directly or indirectly connected with the primary side of the transformer correspondingly;
the secondary side of the transformer is correspondingly connected with the alternating current side of the secondary side circuit;
at least one side between the alternating current side of the primary side circuit and the primary side of the transformer, at least two groups of adjacent phases in the three groups of adjacent phases, and an interphase circuit is arranged between two phases of each group of adjacent phases so as to realize function multiplexing during power transmission.
Preferably, at least two adjacent phases of the three adjacent phases on the ac side of the primary circuit are provided, and the inter-phase circuit provided between two phases of each adjacent phase is a first inter-phase circuit.
Preferably, the first inter-phase circuit includes: a first inductor.
Preferably, the first inter-phase circuit further includes: a switch connected in series with the first inductor.
Preferably, the method further comprises the following steps: and the three resonant circuits are respectively arranged on corresponding phase branches between the primary side circuit and the midpoint of the primary side of the transformer.
Preferably, the resonance circuit includes: at least one first capacitor and at least one second inductor;
each first capacitor, each second inductor and the corresponding primary winding in the transformer are connected in series, one end of each series is connected with the corresponding phase of the alternating current side of the primary circuit, and the other end of each series is connected with the middle point of the primary side of the transformer.
Preferably, each primary winding of the transformer is connected in parallel with a corresponding excitation inductor.
Preferably, at least two groups of adjacent phases at different name ends of the three-phase primary winding of the transformer are provided, and the interphase circuit arranged between two phases of each group of adjacent phases is a second interphase circuit.
Preferably, only two groups of adjacent phases exist in the different-name ends of the three-phase primary windings of the transformer, and a second inter-phase circuit is arranged between two phases of each group of adjacent phases.
Preferably, the second phase-to-phase circuit includes: at least one third inductance of at least one second capacitance connected in series.
Preferably, each primary winding of the transformer is connected in parallel with a corresponding excitation inductor.
Preferably, the excitation inductor is integrated in the transformer.
Preferably, the secondary side circuit is a unidirectional rectifying circuit.
Preferably, only two groups of adjacent phases exist in the same-name ends of the three-phase primary winding of the transformer, and an interphase circuit arranged between two phases of each group of adjacent phases is an excitation inductor.
Preferably, the secondary side circuit is an alternating current/direct current bidirectional conversion circuit.
Preferably, the primary side circuit and the secondary side circuit are both three-phase half-bridge conversion circuits.
Preferably, the method further comprises the following steps: the primary side circuit comprises an input capacitor module arranged on the direct current side of the primary side circuit, and an output capacitor module arranged on the direct current side of the secondary side circuit.
Based on the three-phase LLC resonant DC converter provided by the embodiment of the invention, at least one side between the AC side of the primary side circuit and the primary side of the transformer, at least two groups of adjacent phases in three groups of adjacent phases are provided, and an interphase circuit is arranged between two phases of each group of adjacent phases so as to realize function multiplexing during power transmission; that is, the three-phase LLC resonant dc converter provided in the embodiments of the present invention realizes three-phase conversion energy transmission by multiplexing two inter-phase circuits, and reduces the cost and volume of the circuit compared with the prior art.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a three-phase LLC resonant dc converter in the prior art;
fig. 2 is a schematic structural diagram of three sets of resonant capacitors arranged on the secondary side of a three-phase LLC resonant dc-to-dc converter in the prior art;
fig. 3 is a schematic structural diagram of a three-group resonant inductor and capacitor arranged on a secondary side of a three-phase LLC resonant dc-dc converter in the prior art;
fig. 4 is a schematic structural diagram of a three-phase LLC resonant dc-dc converter according to an embodiment of the present invention;
fig. 5 is a fundamental wave equivalent circuit of each phase when the three-phase LLC resonant dc-dc converter provided in the embodiment of the present invention is in the reverse operation mode;
fig. 6-12 are schematic structural diagrams of six other three-phase LLC resonant dc converters provided in the embodiments of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The embodiment of the invention provides a three-phase LLC resonant direct-current converter, which is used for reducing the circuit volume and the cost.
The schematic structural diagram of the three-phase LLC resonant dc-dc converter is shown in fig. 4 or fig. 6, and includes: a primary side circuit 110, a secondary side circuit 120, and a transformer 130; wherein:
the primary circuit 110 and the secondary circuit 120 are both three-phase conversion circuits; the ac side of the primary side circuit 110 is directly or indirectly connected to the primary side of the transformer 130; the secondary side of the transformer 130 is correspondingly connected with the alternating current side of the secondary side circuit 120; at least one side between the ac side of the primary circuit 110 and the primary side of the transformer 130, at least two adjacent phases of the three adjacent phases, and an inter-phase circuit 140 between two phases of each adjacent phase to realize the multiplexing of the resonance function in the reverse operation mode when transmitting energy from the secondary side to the primary side.
In general, each primary winding of the transformer 130 is connected in parallel with a corresponding excitation inductor (e.g. L in fig. 4 or 6)mA、LmBAnd LmCAs shown), and preferably, these excitation inductors may be integrated within the transformer 130. The primary circuit 110 and the secondary circuit 120 are three-phase half-bridge conversion circuits, and the three-phase LLC resonant dc-dc converter further includes an input capacitor module (as shown in C1 in fig. 4 or fig. 5) disposed on the dc side of the primary circuit 110, and an output capacitor module (as shown in C2 in fig. 4 or fig. 5) disposed on the dc side of the secondary circuit 120.
The primary circuit 110 includes a plurality of switching tubes (shown as S1-S6 in fig. 4-9) and a parasitic diode connected in parallel with each switch. The first switching tube S1 and the second switching tube S2 are connected in series to form a first arm of the primary circuit 110, the third switching tube S3 and the fourth switching tube S4 are connected in series to form a second arm of the primary circuit 110, and the fifth switching tube S5 and the sixth switching tube are connected in series to form a third arm of the primary circuit 110. Similarly, the secondary side circuit 120 includes a plurality of switching tubes (shown as S7-S12 in fig. 4-9) and a parasitic diode connected in parallel with each switching tube. The specific connection relationship is as follows:
the primary side circuit 110 includes: a first bridge arm which is connected with an input power supply V1 in parallel and is formed by connecting a first switch tube S1 and a second switch tube S2 in series, wherein the drain electrode of the first switch tube S1 is connected with the anode of the input power supply V1, and the source electrode of the second switch tube S2 is connected with the cathode of the input power supply V1; a second bridge arm which is connected with the input power supply V1 in parallel and is formed by connecting a third switching tube S3 and a fourth switching tube S4 in series, wherein the drain electrode of the third switching tube S3 is connected with the anode of the input power supply V1, and the source electrode of the fourth switching tube S4 is connected with the cathode of the input power supply V1; and a third bridge arm which is connected with the input power supply V1 in parallel and is formed by connecting a fifth switching tube S5 and a sixth switching tube S6 in series, wherein the drain electrode of the fifth switching tube S5 is connected with the anode of the input power supply V1, and the source electrode of the sixth switching tube S6 is connected with the cathode of the input power supply V1. The secondary circuit 120 also includes a first arm to a third arm (i.e., S7-S12 in fig. 4-9), and the connection relationship of the first arm to the third arm is the same as that of each arm in the primary circuit 110, which is not described again.
In the three-phase LLC resonant dc-dc converter, three sets of adjacent phases exist on the ac side of the primary circuit 110, for example, points a and B, points a and C, and points B and C in fig. 4 are respectively a set of adjacent phases. Three groups of adjacent phases also exist between the primary sides of the transformer 130, for example, points D and E, points D and F, and points E and F in fig. 6 are respectively a group of adjacent phases.
It should be noted that, at least one side between the ac side of the primary side circuit 110 and the primary side of the transformer 130, at least two adjacent phases of the three adjacent phases, and an interphase circuit 140 is disposed between two phases of each adjacent phase, specifically including the following cases:
first, at least two adjacent phases of the three adjacent phases on the ac side of the primary circuit 110, namely, two or three arbitrary groups of the three groups of points a and B, a and C, and B and C, are selected, and a first interphase circuit 210 is disposed between two adjacent phases of each group. The embodiment of the present invention is illustrated by taking an example that a first inter-phase circuit 210 is respectively disposed between two adjacent phases of a point a and a point B, and a point B and a point C, and a structural schematic diagram of the first inter-phase circuit 210 is shown in fig. 4, where the first inter-phase circuit 210 includes a first inductor (e.g., L in fig. 4)m2AAnd Lm2BShown); at this time, the three-phase LLC resonant dc converter further includes three resonant circuits 220, each resonant circuit 220 is respectively disposed on a corresponding phase branch between the primary side circuit 110 and a primary side midpoint of the transformer 130, where the primary side midpoint refers to N1 of the connection of the synonym end of each primary side winding in fig. 4; that is, a resonant circuit 220 and a corresponding primary winding are connected in series on each branch between the ac side of the primary circuit 110 and the midpoint of the primary side of the transformer 130; when all or part of the components in the resonant circuit 220 are disposed between the ac side of the primary circuit 110 and the corresponding primary winding of the transformer 130, the ac side of the primary circuit 110 is indirectly connected to the primary side of the transformer 130; when all of the components of the resonant circuit 220 are disposed between the synonym terminal of the corresponding primary winding of the transformer 130 and the primary midpoint N1, the ac side of the primary circuit 110 is directly connected to the primary side of the transformer 130. Each resonant circuit 220 includes at least one first capacitor and at least one second inductor, each first capacitor, each second inductor, and a corresponding primary winding in the transformer 130 are connected in series, the series connection sequence is not limited, one end of the series connection is connected to the ac side of the primary circuit 110, and the other end of the series connection is connected to the primary midpoint of the transformer 130. It should be noted that the number and the series order of the first capacitor and the second inductor may be set by a skilled person according to the actual application, and are not specifically limited, as long as each resonant circuit 220 is connected in series with the primary winding of the transformer 130. In the embodiment of the present invention, in FIG. 4, a first capacitor and a second inductor (shown as L in FIG. 4, respectively) are usedr1AAnd Cr1A、Lr1BAnd Cr1BAnd Lr1CAnd Cr1C) For example, as shown in fig. 4, one side of the second inductor is correspondingly connected to the ac side of the primary side circuit 110, and the other side of the second inductor is connected to the dotted terminal of the corresponding primary side winding of the transformer 130 through the first capacitor; alternatively, one side of the first capacitor is connected to the ac side of the primary circuit 110, and the other side of the first capacitor is connected to the same-name terminal (not shown) of the corresponding primary winding of the transformer 130 through the first inductor.
It should be noted that, in the prior art, the transformer adopts a star-connected bidirectional three-phase LLC dc resonant converter, and its structural schematic diagram is shown in fig. 1, and includes a primary side, a secondary side and a resonant cavity, the primary side includes an input filter capacitor (as shown in fig. 1 or C1 in fig. 3 and Vin in fig. 2) and a three-phase full-bridge inverter circuit (as shown in fig. 1-Q6 of power switch tubes Q1-Q6) connected in parallel therewith, the secondary side includes an output filter capacitor (as shown in fig. 1C 2, Vout in fig. 2 or C8 in fig. 3) and a three-phase full-bridge rectifier circuit (i.e. power switch tubes Q7-Q12 in fig. 1-3) connected in parallel therewith, and its resonant cavity includes a resonant inductor (as shown in fig. 1L, and Qr1-Lr3L1-L3 in fig. 2 and 3), resonant capacitance (e.g., C in fig. 1)r1-Cr3C13-C15 in fig. 2 or C2-C4 in fig. 3), and excitation inductance (L in fig. 1 and 2)m1-Lm3Shown) and an isolation transformer (shown as T1-T3 in fig. 1-3). In general, the bidirectional three-phase LLC resonant dc converter is further provided with a controller, which is connected to each power switching tube to control on/off of the power switching tube, so as to control the bidirectional three-phase LLC resonant dc converter to switch the operating state. Although the bidirectional three-phase LLC direct-current resonant converter has self-current-sharing capability, when the bidirectional three-phase LLC direct-current resonant converter reversely transmits, because the primary side excitation inductor is clamped by the secondary side square wave, namely, the circuit is in an LC resonance state, reverse boosting cannot be performed. Therefore, the prior art proposes that three groups of resonant capacitors (as shown in C16, C17 and C18 in fig. 2) are symmetrically added to the secondary side, and the structural diagram thereof is shown in fig. 2; alternatively, three sets of resonant inductors and capacitors (such as L4 and C5, L5 and L5 in FIG. 3) are symmetrically added on the secondary sideC6 and L6 and C7), the structure of which is schematically shown in fig. 3, to improve the reverse voltage gain; however, these two methods increase the number of components, which leads to an increase in circuit cost and an increase in the size of the converter.
In the first topology structure provided in this embodiment, the primary circuit 110 and the secondary circuit 120 of the three-phase LLC resonant dc converter are both ac/dc bidirectional conversion circuits, that is, the three-phase LLC resonant dc converter is also a bidirectional converter, and can be applied to energy bidirectional flow occasions such as high-power charging piles and energy storage. When the power transmission circuit is in a forward operation mode, that is, energy is transmitted from the primary side to the secondary side, the first inductor in the first inter-phase circuit 210 does not participate in resonance, the resonance elements are the second inductor and the first capacitor connected in series in the three resonance circuits and the excitation inductor in the transformer 130, and the energy transmission path is the same as that in the prior art. When the three-phase LLC resonant dc converter is in a reverse operating mode, that is, energy is transmitted from the secondary side to the primary side, at this time, the excitation inductance in the transformer 130 does not participate in resonance, the resonant elements are the second inductance and the first capacitance connected in series in the three resonant circuits 220 and the first inductance in the first inter-phase circuit 210, and at this time, the fundamental wave equivalent circuit of each phase is as shown in fig. 5, and the equivalent circuit is identical to the fundamental wave equivalent circuit of the conventional LLC, and can implement boosting; also through two interphase circuits that set up rather than original resonant element, can control the fundamental wave equivalent circuit of each phase unanimous with the fundamental wave equivalent circuit of traditional LLC, and then realize that this three-phase LLC resonant direct current converter voltage gain's promotion, strengthened gain control function under reverse mode of operation to can assist the soft switch to realize, only increased two interphase circuits moreover, resonant element is less, compares prior art and has reduced the cost and the volume of circuit.
Secondly, at least two groups of adjacent phases are arranged among the different-name ends of the three-phase primary winding of the transformer 130, a second inter-phase circuit 310 is arranged between two phases of each group of adjacent phases, any two of the three different-name ends of the three-phase primary winding of the transformer 130 are respectively a group of adjacent phases, namely, points D and E, points D and F and points E and F in fig. 6A second inter-phase circuit 310 is illustrated as an example, and a schematic structural diagram thereof is shown in fig. 6, where the second inter-phase circuit 310 includes at least one second capacitor and at least one third inductor connected in series, and a second capacitor is connected in series with a third inductor in fig. 6 (e.g. L in fig. 6)r1AAnd Cr1AAnd Lr1BAnd Cr1BShown) are shown as examples, wherein: one end of the third inductor is connected to one end of the second capacitor, and the other end of the third inductor and the other end of the second capacitor are respectively used as two ends of the second phase circuit 310. It should be noted that fig. 6 is only an example of the second topology, and the second topology may also include two other groups of adjacent phases than those shown in fig. 6, for example, a point D and a point F, and a point E and a point F, or one second inter-phase circuit 310 may be respectively disposed between three groups of adjacent phases, and the second inter-phase circuit 310 may include a plurality of third inductors connected in series with a plurality of second capacitors, and the series connection sequence may be arbitrarily set, which are within the protection scope of the embodiment of the present invention and will not be described again.
In the second topology, the three-phase LLC resonant dc converter may be a bidirectional converter (as shown in fig. 6) or a unidirectional converter (as shown in fig. 10), that is, the secondary circuit 120 may be an ac/dc bidirectional converter circuit (as shown in fig. 6) or a unidirectional rectifier circuit, such as a diode rectifier bridge (as shown at 120 in fig. 10). The three-phase LLC resonant direct-current converter is not added with any element, only improves three original resonant circuits, multiplexes inductors and capacitors in the resonant circuits, namely two or three second phase circuits 310 are respectively utilized to realize power transmission of the unidirectional converter and a forward working mode or a reverse working mode of the bidirectional converter, can achieve the same effect as that shown in figure 5 when the bidirectional converter is in the reverse working mode, and obviously reduces the circuit volume and the cost.
Preferably, only two groups of adjacent phases exist in different name ends of the three-phase primary winding of the transformer, and a second inter-phase circuit is arranged between two phases of each group of adjacent phases. At this time, as shown in fig. 6 or fig. 10, the three-phase LLC resonant dc converter does not add any element, but improves the original three resonant circuits, and its adjacent phase uses the inductance and capacitance in the resonant circuit, reduces one resonant circuit, and the circuit volume and cost are lower.
Thirdly, at least two groups of adjacent phases in the three groups of adjacent phases on the ac side of the primary circuit 110 are provided with the first inter-phase circuit 210 between two phases of each group of adjacent phases, and at the same time, at least two groups of adjacent phases in the different-name ends of the three-phase primary winding of the transformer 130 are provided with the second inter-phase circuit 310 between two phases of each group of adjacent phases, and the structure thereof has various combination forms, one of which is shown in fig. 7, wherein the structure and the arrangement mode of the first inter-phase circuit 210 and the second inter-phase circuit 310 are the same as those in the two cases, and are not described in detail.
The topology shown in fig. 7 is a combined structure of fig. 4 and fig. 6, and the resonant circuit and the first interphase circuit 210 are multiplexed, so that the same technical effects as those in fig. 4 and fig. 6 can be achieved; that is, the multiple setting modes of the first topology and the multiple setting modes of the second topology may be respectively combined in a one-to-one correspondence manner to obtain a third topology, and the purpose of function reuse in the reverse working mode when energy is transmitted from the secondary side to the primary side can be achieved, which is not described herein again.
Fourthly, only two groups of adjacent phases exist in the same-name end of the three-phase primary winding of the transformer, and an interphase circuit arranged between two phases of each group of adjacent phases is an excitation inductor.
That is, in the case where the transformer does not integrate the field inductance, an external field inductance (L as shown in fig. 11 and 12) may be usedmABAnd LmBC) Multiplexing, as shown in fig. 12, can also reduce components, and reduce the size and cost of the unidirectional converter or the bidirectional converter.
It should be noted that fig. 12 is a case of individually multiplexing the excitation inductors, fig. 11 is a case of simultaneously multiplexing the first inter-phase circuit and the excitation inductors, and a case of simultaneously multiplexing the second inter-phase circuit and the excitation inductors and a case of simultaneously multiplexing the first inter-phase circuit, the second inter-phase circuit, the excitation inductors, and the third inter-phase circuit, are not shown one by one, and are all within the protection scope of the present application.
In the three-phase LLC resonant dc converter provided in the embodiments of the present invention, three sets of adjacent phases exist on at least one of the ac side of the primary circuit 110 or the synonym end of the three-phase primary winding of the transformer 130, at least two sets of adjacent phases are selected from the three sets of adjacent phases, and at least one interphase circuit is provided between two phases of each set of adjacent phases, so that function multiplexing during power transmission can be realized; compared with the prior art, the three-phase LLC resonant direct-current converter provided by the embodiment of the invention realizes three-phase conversion energy transmission by multiplexing two interphase circuits under the condition of adding few or even no resonant elements, and reduces the system volume and cost.
It should be noted that, in the above embodiment, besides that the multiplexing of the first interphase circuit 210 can be applied to the bidirectional converter only, several other multiplexing cases can be applied to the unidirectional converter or the bidirectional converter. The reason is that, in the topology in which the first inter-phase circuit 210 is provided (i.e. fig. 4 and 7), when the three-phase LLC resonant dc-dc converter is in the forward operation mode, the first inductor in the first inter-phase circuit 210 still flows current though not participating in resonance, and thus generates loss. Therefore, in order to reduce the loss and further improve the system efficiency, on the basis of the above embodiments, the embodiments of the present invention further provide the following topologies, whose schematic structural diagrams are shown in fig. 8 and fig. 9, where:
the first inter-phase circuit 210 further includes: a switch (shown as S13 and S14 in fig. 8 or fig. 9) connected in series with the first inductor.
According to the three-phase LLC resonant direct-current converter provided by the embodiment of the invention, the switches are arranged in the first inter-phase circuit 210, the switches are controlled to be switched off when the three-phase LLC resonant direct-current converter is in the forward working mode, and the switches are controlled to be switched on when the three-phase LLC resonant direct-current converter is in the reverse working mode, so that the loss is avoided, and the system efficiency is improved.
The rest of the principle is the same as the above embodiments, and is not described in detail here.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the above description of the disclosed embodiments, the features described in the embodiments in this specification may be replaced or combined with each other to enable those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (17)

1. A three-phase LLC resonant dc converter, comprising: a primary side circuit, a secondary side circuit and a transformer; wherein:
the primary side circuit and the secondary side circuit are both three-phase conversion circuits;
the alternating current side of the primary side circuit is directly or indirectly connected with the primary side of the transformer correspondingly;
the secondary side of the transformer is correspondingly connected with the alternating current side of the secondary side circuit;
at least one side between the alternating current side of the primary side circuit and the primary side of the transformer, at least two groups of adjacent phases in the three groups of adjacent phases, and an interphase circuit is arranged between two phases of each group of adjacent phases so as to realize function multiplexing during power transmission.
2. The three-phase LLC resonant dc converter according to claim 1, wherein at least two of the three sets of adjacent phases on the ac side of the primary circuit are adjacent phases, and the inter-phase circuit provided between two phases of each set of adjacent phases is a first inter-phase circuit.
3. A three-phase LLC resonant dc-to-dc converter according to claim 2, wherein said first phase-to-phase circuit comprises: a first inductor.
4. A three-phase LLC resonant dc-to-dc converter according to claim 3, wherein said first phase-to-phase circuit further comprises: a switch connected in series with the first inductor.
5. The three-phase LLC resonant dc converter of claim 2, further comprising: and the three resonant circuits are respectively arranged on corresponding phase branches between the primary side circuit and the midpoint of the primary side of the transformer.
6. A three-phase LLC resonant DC converter according to claim 5, wherein said resonant circuit comprises: at least one first capacitor and at least one second inductor;
each first capacitor, each second inductor and the corresponding primary winding in the transformer are connected in series, one end of each series is connected with the corresponding phase of the alternating current side of the primary circuit, and the other end of each series is connected with the middle point of the primary side of the transformer.
7. The three-phase LLC resonant dc converter as claimed in claim 2, wherein each primary winding of the transformer is connected in parallel with a corresponding excitation inductor.
8. A three-phase LLC resonant DC converter according to any one of claims 2 to 7, wherein said secondary side circuit is an AC/DC bidirectional conversion circuit.
9. The three-phase LLC resonant dc converter according to claim 1, wherein at least two sets of adjacent phases of different-name ends of three-phase primary windings of the transformer are provided, and an inter-phase circuit provided between two phases of each set of adjacent phases is a second inter-phase circuit.
10. The three-phase LLC resonant dc converter according to claim 9, wherein there are only two sets of adjacent phases in the synonym terminals of the three-phase primary windings of the transformer, and a second inter-phase circuit is provided between two phases of each set of adjacent phases.
11. The three-phase LLC resonant dc converter of claim 9, wherein said second phase-to-phase circuit comprises: at least one second capacitor and at least one third inductor connected in series.
12. The three-phase LLC resonant dc converter as claimed in claim 9, wherein each primary winding of the transformer is connected in parallel with a corresponding excitation inductor.
13. A three-phase LLC resonant dc converter according to claim 7 or 12, characterized in that the magnetizing inductance is integrated in the transformer.
14. The three-phase LLC resonant dc converter according to claim 1, wherein only two sets of adjacent phases exist in the same-name ends of the three-phase primary windings of the transformer, and an inter-phase circuit provided between two phases of each set of adjacent phases is an excitation inductor.
15. A three-phase LLC resonant dc converter according to any of claims 9-12 and 14, characterized in that the secondary side circuit is a unidirectional rectifying circuit or an ac/dc bidirectional converting circuit.
16. A three-phase LLC resonant dc-to-dc converter as claimed in any one of claims 1-7, 9-12, 14, characterized in that the primary and secondary circuits are each a three-phase half-bridge converter circuit.
17. A three-phase LLC resonant dc-to-dc converter according to any of claims 1-7, 9-12, 14, further comprising: the primary side circuit comprises an input capacitor module arranged on the direct current side of the primary side circuit, and an output capacitor module arranged on the direct current side of the secondary side circuit.
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