CN112886821A - Magnetic integrated structure suitable for CLTLC converter - Google Patents

Magnetic integrated structure suitable for CLTLC converter Download PDF

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Publication number
CN112886821A
CN112886821A CN202110018313.XA CN202110018313A CN112886821A CN 112886821 A CN112886821 A CN 112886821A CN 202110018313 A CN202110018313 A CN 202110018313A CN 112886821 A CN112886821 A CN 112886821A
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China
Prior art keywords
transformer
magnetic
converter
transformers
resonant
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Inventor
王议锋
刘瑞欣
韩富强
陈庆
肖小龙
刘瑞煌
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Tianjin University
State Grid Jiangsu Electric Power Co Ltd
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Tianjin University
State Grid Jiangsu Electric Power 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
    • H02M3/33507—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 with automatic control of the output voltage or current, e.g. flyback converters
    • H02M3/33523—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 with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/24—Magnetic cores
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/28—Coils; Windings; Conductive connections
    • H01F27/2804—Printed windings
    • 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
    • H02M1/44—Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/28—Coils; Windings; Conductive connections
    • H01F27/2804—Printed windings
    • H01F2027/2809—Printed windings on stacked layers
    • 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

Abstract

The invention discloses a magnetic integrated structure suitable for a CLTLC converter, wherein the CLTLC converter comprises two resonant inductors, two resonant capacitors and two high-frequency transformers, and is characterized in that each high-frequency transformer consists of two sub-transformers, the turn ratio of each sub-transformer is different, and the primary sides and the secondary sides of the sub-transformers forming each high-frequency transformer are connected in series or in parallel; integrating the high-frequency transformer and the corresponding resonant inductor to form an EI magnetic core structure, wherein air gaps are arranged on a middle column and side columns of the EI magnetic core structure; and finally, all the high-frequency transformers and the resonant inductors form an EIE type magnetic core structure together.

Description

Magnetic integrated structure suitable for CLTLC converter
Technical Field
The invention relates to the field of magnetic sets of multi-resonant converters, in particular to a magnetic integration structure suitable for a CLTLC converter.
Background
The multi-resonance converter is a kind of direct current converter with excellent performance, and has been widely used due to its advantages of high efficiency, high frequency, high power density, low electromagnetic interference, etc. In addition, due to the fact that the number and the connection mode of passive devices in the resonant cavity are different, the passive devices can show more flexible resonant characteristics and more excellent performance. The research aiming at the converter is endlessly developed, and various topological structures are provided.
The CLTLC converter is a multi-resonance soft-switching DC converter with a double-transformer structure, and six resonance elements are arranged in a resonance cavity of the CLTLC converter, and comprise two resonance inductors, two resonance capacitors and two high-frequency transformers. Through detailed theoretical analysis and reasonable parameter configuration, the converter can simultaneously transmit fundamental wave and third harmonic active power in a wider frequency range, and the current utilization rate of the resonant cavity is improved. In addition, the switch tube and the diode of the converter can realize good soft switching performance, and the switching loss is effectively reduced. Although the converter achieves a good conversion effect, the resonant elements in the resonant cavity, particularly the magnetic elements (inductors and transformers) are discrete magnetic elements, the number is large, the size, the weight and the power density of the converter are difficult to improve, and further application and popularization of the converter are limited.
There are many studies currently being conducted on the magnetic integration technology of the multi-resonant converter. The magnetic integration design of the resonant converter can be simplified by using the leakage inductance of the transformer as the resonant inductance. Therefore, some researchers have proposed that the desired leakage inductance value be obtained by selecting a low permeability material to construct the magnetic shunt. By means of the structure, the leakage inductance value is adjusted by changing the relative permeability and the thickness of the magnetic shunt, and therefore the inductor connected with the transformer in series is effectively integrated. However, the introduction of the magnetic shunt increases the complexity of the transformer structure, and some researchers have proposed that the primary winding and the secondary winding of the transformer are completely separated to control the leakage inductance. Therefore, the coupling degree of the windings can be changed by adjusting the distance between the windings, so that the size of the leakage inductance can be effectively controlled. However, in this method, the leakage flux mainly flows through the air, which causes additional eddy current loss and electromagnetic interference.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a magnetic integrated structure suitable for a CLTLC converter aiming at the problems of more resonant elements, particularly more magnetic elements and larger volume in a resonant cavity of the CLTLC multi-resonant converter. All magnetic elements in the transducer are effectively integrated. Therefore, the functions of a plurality of magnetic pieces can be realized by a single magnetic piece, the aim of magnetic integration is fulfilled, the number and the volume of magnetic elements are reduced, and the power density of the converter is improved. The performance of the converter is improved.
The purpose of the invention is realized by the following technical scheme:
a magnetic integrated structure suitable for a CLTLC converter comprises two resonant inductors, two resonant capacitors and two high-frequency transformers, and is characterized in that each high-frequency transformer consists of two sub-transformers, the turn ratio of each sub-transformer is different, and the primary sides and the secondary sides of the sub-transformers forming each high-frequency transformer are connected in series or in parallel; integrating each high-frequency transformer with a corresponding resonant inductor to form an EI magnetic core structure, wherein air gaps are arranged on a middle column and side columns of the EI magnetic core structure; and finally, all the high-frequency transformers and the resonant inductors form an EIE type magnetic core structure together.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
1. the invention provides a magnetic integration design method suitable for a multi-resonance converter, and all magnetic elements in a resonance cavity can be effectively integrated into one magnetic core.
2. The novel magnetic core structure can integrate two independent transformers.
3. By changing the size of air gap magnetic resistance under different magnetic columns in the magnetic core structure, the excitation inductance and leakage inductance of the transformer can be flexibly controlled, so that the transformer and the resonance inductance connected in series with the transformer can be effectively integrated.
Drawings
FIG. 1 is a resonant cavity structure of a CLTLC converter;
FIG. 2 shows a transformer T1The design process of (2);
FIG. 3 is an integrated post-transformer T1The structure diagram of the EI magnetic core;
FIG. 4 is a transformer T1The T-type equivalent model of (1);
FIG. 5 is a structural diagram of the improved EI-type magnetic core;
FIG. 6 is a structural view of the improved EIE type magnetic core;
fig. 7 is a simulation diagram of the structure of the improved EIE-type magnetic core.
Detailed Description
The invention is described in further detail below with reference to the figures and specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention integrates a novel transformer magnetic core structure which can flexibly control the excitation inductance and the leakage inductance, thereby effectively integrating the transformer and the resonance inductance connected with the transformer in series.
In this example, a CLTLC multi-resonant converter was taken as an example to study the magnetic integration technology. Fig. 1 shows the resonator structure of a CLTLC converter. The resonant unit of the converter has 6 resonant elements including two resonant inductors L1，L2Two resonant capacitors C1，C2And two high-frequency transformers T1And T2，T1And T2Respectively is np:nsAnd np':ns'。
In order to improve the performance of the transformer, the concept of a matrix transformer is proposed. The matrix transformer is essentially a set of a plurality of transformers, wherein the turn ratio of each transformer is not fixed, the required turn ratio requirement is realized by connecting a primary side winding and a secondary side winding of the plurality of transformers in series or in parallel, the matrix transformer is the same as a single transformer in function, and the matrix transformer has the obvious advantage of reducing the number of PCB (printed circuit board) layers and the winding loss of the transformer.
However, the design of the matrix transformer also brings some disadvantages, such as the increase of the number of the magnetic cores, the increase of the volume of the magnetic cores, and the aggravation of the magnetic core loss. In the design method, the leakage inductance of the transformer is not controllable, and in order to effectively control the leakage inductance value, the uncoupled degree between the primary side winding and the secondary side winding needs to be increased. Compared with the completely uniform design of the windings in the matrix transformer, the winding arrangement scheme is considered to be adjusted, and the scheme that the primary side windings and the secondary side windings are unevenly distributed is adopted.
By means of a transformer T1For example, as shown in FIG. 2, first, T is1Sub-transformer T based on UI magnetic core and split into two different turn ratios11And T12. According to T1The ratio of the primary winding and the secondary winding of each sub-transformer is determined by the required ratio(s) (connected in series or in parallel).
Then, the sub-transformer T is connected11And T12The EI core structure shown in fig. 3 can be obtained by integration. And writing corresponding self-inductance matrixes and mutual inductance matrixes for the columns of each sub-transformer, and writing corresponding voltage and current equations according to the connection mode of primary side windings and secondary side windings of the sub-transformers. Thus, transformer T can be obtained1The self-inductance and mutual-inductance matrix of (2) is shown as formula (1). Wherein L is11、L22The self-inductance, L, of the primary side winding and the secondary side winding of the transformer12Is the mutual inductance. v. ofpAnd vsFor the integrated primary and secondary side voltages, ipAnd isIs the corresponding current.
Figure BDA0002887799670000031
To simplify the analysis, a graph was constructed4 transformer T-type equivalent model, transformer T1Has an excitation inductance of Lm1The primary side leakage inductance and the secondary side leakage inductance are Lk11And Lk12. V can be obtained from the T-type equivalent modelpExpression (c):
Figure BDA0002887799670000032
by combining the above formulas, T can be obtained1Excitation inductance Lm1Primary side leakage inductance is the same as L11、L12The mathematical relationship of (1):
Figure BDA0002887799670000033
L11＝Lk12+Lm1 (4)
will excite the magnetic inductance Lm1Converted to the secondary side to obtain L22The mathematical expression of (a):
Figure BDA0002887799670000041
solving the above formula can obtain the transformer T1Primary side leakage inductance and secondary side leakage inductance. According to the above analysis, the EI core transformer structure after integration has a built-in leakage inductance Lk11And Lk12However, the ratio of the leakage inductance to the excitation inductance is a fixed value, and it cannot be effectively controlled separately. In order to enhance the versatility of the transformer design method, an improved EI core structure is proposed as shown in fig. 5, which introduces a new air gap with a length l in the center pillar of the EI core shown in fig. 3gbThe air gap length of the two outer side columns is lga. In this configuration, the magnetic fluxes generated by the left and right windings in the center legs are opposite in direction to cancel part of the magnetic fluxes, so that the length of the center leg can be reduced appropriately.
Through mathematical derivation, under the improved EI magnetic core structure, the excitation inductance and the leakage inductance of the transformer are both related to the air gap magnetic resistance of the outer side column and the middle column. Therefore, the size of the air gap magnetic resistance can be determined according to the excitation inductance and the leakage inductance value required by the converter, and the cross section area and the air gap length of different magnetic poles can be adjusted according to the value of the air gap magnetic resistance. In this integration scheme, the leakage inductance of the transformer is controllable and exploited as a resonant inductance. This not only effectively reduces the volume of the magnetic element, but also achieves good parasitic control and automatic production of the transducer
Thus, the transformer and the resonant inductor in series with it can be integrated into one EI core, whereas in a CLTLC converter, two transformers and two resonant inductors in common need to be integrated. The final integration scheme employs an EIE core as shown in figure 6. Compared with two EI-type magnetic cores, the EIE-type magnetic core omits one I-type magnetic core. Due to T1And T2The power sharing is different, so the magnetic flux generated in the common I-shaped magnetic core is different in size, the magnetic flux can be partially cancelled, and in addition, the common magnetic core provides the transformer T1And T2A low-magnetic-resistance magnetic circuit is provided, and theoretically, decoupling control can be realized between transformers.
Specifically, fig. 5 is a structural view of an EI type core. Compared with the EI-type magnetic core structure shown in FIG. 3, the improved structure introduces a new air gap at the center pillar of the magnetic core, and the air gap length is lgbThe air gap length of the two outer side columns is lga. In this configuration, the magnetic fluxes generated by the left and right windings in the center leg are opposite in direction to cancel part of the magnetic flux, so that the length of the center leg can be appropriately reduced compared to the EI core. Therefore, the air gap magnetic resistance of the middle column and the outer column can be changed by changing the cross section area and the length of the air gap of the middle column and the outer column, and further, the excitation inductance and the leakage inductance of the transformer after integration are reasonably controlled.
Fig. 6 is a structural view of a final EIE type core. This structure allows the integration of all the magnetic elements of the CLTLC converter. Compared with two improved EI magnetic cores, the EIE magnetic core omits one I-shaped magnetic core. And for the intermediate type I core, the transformer T1And T2The magnetic fluxes generated in the magnetic flux generating units are opposite in direction, and can cancel part of magnetismThe method is simple. Therefore, the height of the core can be appropriately reduced, and further, the I-type core gives the transformer T1And T2A low-magnetic-resistance magnetic circuit is provided, and theoretically, decoupling control can be realized between transformers.
Fig. 7 is a simulation of an EIE-type core structure. The magnetic induction B and the magnetic field H distribution in air of the improved EIE core structure can be seen from the figure. It can be seen that a large amount of magnetic flux flows through the center leg of the core, and the magnetic flux in this portion is mainly leakage flux. The leakage flux in air is less compared to the magnetic core. Although the magnetic flux density of the center pillar is high, the maximum value of the magnetic flux density is limited within a reasonable range, and the working requirement of the converter can be well met.
The present invention is not limited to the above-described embodiments. The foregoing description of the specific embodiments is intended to describe and illustrate the technical solutions of the present invention, and the above specific embodiments are merely illustrative and not restrictive. Those skilled in the art can make many changes and modifications to the invention without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (1)

1. A magnetic integrated structure suitable for a CLTLC converter comprises two resonant inductors, two resonant capacitors and two high-frequency transformers, and is characterized in that each high-frequency transformer consists of two sub-transformers, the turn ratio of each sub-transformer is different, and the primary sides and the secondary sides of the sub-transformers forming each high-frequency transformer are connected in series or in parallel; integrating each high-frequency transformer with a corresponding resonant inductor to form an EI magnetic core structure, wherein air gaps are arranged on a middle column and side columns of the EI magnetic core structure; and finally, all the high-frequency transformers and the resonant inductors form an EIE type magnetic core structure together.
CN202110018313.XA 2021-01-07 2021-01-07 Magnetic integrated structure suitable for CLTLC converter Pending CN112886821A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113436850A (en) * 2021-06-30 2021-09-24 天津大学 High-frequency segmented air gap planar transformer

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Publication number Priority date Publication date Assignee Title
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CN102611315A (en) * 2012-03-22 2012-07-25 华为技术有限公司 Resonant switching circuit
CN108538552A (en) * 2018-01-22 2018-09-14 许继电源有限公司 A kind of magnetic core arrangement and its transformer of integrated resonant inductance
CN111883351A (en) * 2020-07-23 2020-11-03 天津大学 Magnetic core structure based on multi-resonance converter

Patent Citations (4)

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Publication number Priority date Publication date Assignee Title
CN102594107A (en) * 2012-03-15 2012-07-18 华中科技大学 LCL filter utilizing integrated inductors
CN102611315A (en) * 2012-03-22 2012-07-25 华为技术有限公司 Resonant switching circuit
CN108538552A (en) * 2018-01-22 2018-09-14 许继电源有限公司 A kind of magnetic core arrangement and its transformer of integrated resonant inductance
CN111883351A (en) * 2020-07-23 2020-11-03 天津大学 Magnetic core structure based on multi-resonance converter

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王议锋 等: "一种双变压器结构的多谐振型软开关直流变换器", 《电工技术学报》 *

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* Cited by examiner, † Cited by third party
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CN113436850A (en) * 2021-06-30 2021-09-24 天津大学 High-frequency segmented air gap planar transformer

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Application publication date: 20210601