WO2016005526A1 - Transformateur à prise médiane - Google Patents

Transformateur à prise médiane Download PDF

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Publication number
WO2016005526A1
WO2016005526A1 PCT/EP2015/065761 EP2015065761W WO2016005526A1 WO 2016005526 A1 WO2016005526 A1 WO 2016005526A1 EP 2015065761 W EP2015065761 W EP 2015065761W WO 2016005526 A1 WO2016005526 A1 WO 2016005526A1
Authority
WO
WIPO (PCT)
Prior art keywords
layer
centre
winding
transformer
primary
Prior art date
Application number
PCT/EP2015/065761
Other languages
English (en)
Inventor
Ningning Wang
Cian O'MATHUNA
Original Assignee
University College Cork - National University Of Ireland, Cork
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University College Cork - National University Of Ireland, Cork filed Critical University College Cork - National University Of Ireland, Cork
Publication of WO2016005526A1 publication Critical patent/WO2016005526A1/fr

Links

Classifications

    • 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
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F21/00—Variable inductances or transformers of the signal type
    • H01F21/12—Variable inductances or transformers of the signal type discontinuously variable, e.g. tapped
    • 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
    • H01F27/29—Terminals; Tapping arrangements for signal inductances
    • 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
    • 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
    • H01F2027/2819—Planar transformers with printed windings, e.g. surrounded by two cores and to be mounted on printed circuit

Definitions

  • the present invention is concerned with transformers. More particularly, the invention relates to centre-tapped micro-transformers.
  • Integrated transformers are generally constructed using spiral coils for windings due to their high inductance density. These coils can be either fabricated on silicon or on a printed circuit board (PCB).
  • PCB printed circuit board
  • One arrangement is known as interleaved primary and secondary windings, and is shown in the air core transformer of Figure 1 .
  • This arrangement is typically realized using a single layer of metal. However, this results in a transformer having poor coupling and low efficiency, due to the size of the single layer footprint when compared with transformers which use double layers of metal.
  • the second typical transformer winding arrangement is where the primary and secondary windings of the transformer are stacked using multiple layers of metal, with the primary winding on one layer and the secondary winding on another layer.
  • the cross section of such a typical stacked arrangement using two layers of metal is shown in Figure 2.
  • US2007/0001794 discloses a transformer design for air-core application for replacing ferrite core structure and made using a PCB process for large feature sizes.
  • Alford provides a substantially two-dimensional solution for performing the DSL transformer function which comprises of a planar structure characterized by the absence of a ferromagnetic element.
  • EP1 6381 18, Alps Electric discloses an inexpensive manufacturing process of a transformer by using an inexpensive insulating substrate, by forming a primary coil and a secondary coil on both surfaces of the insulating substrate.
  • the coils are concentrically arranged and based on micro-fabrication techniques with all the layers deposited in a sequential order.
  • Other patent publications in the art of transformers include JP2012169 410 and JP2000277354.
  • a centre tap is a contact made to a point normally halfway along a winding of a transformer or inductor.
  • the centre tap provides an extra connection along with the usual connections at the two ends of each of two windings.
  • a centre tapped transformer cannot be realized using spiral coils by adopting either the interleaved winding arrangement or the stacked winding arrangement described above. This is due to space constraints, as well as the resulting asymmetric primary and secondary windings.
  • having a centre tap is critical for transformers in certain applications, such as in power converter topologies, for example a push pull converter.
  • At least one first layer comprising a first portion of a primary winding interleaved with a first portion of a secondary winding
  • At least one second layer comprising a second portion of the primary winding interleaved with a second portion of the secondary winding
  • the transformer provides high inductance density and high coupling factor when compared to conventional centre tapped transformers.
  • the invention provides a magnetic core.
  • the magnetic core can provide higher inductance.
  • the symmetry of windings is not critical since the air-core inductance is much smaller compared to the magnetic core inductance.
  • the transformer of the invention allows minimum leakage inductance and the convenience of constructing centre taps for the ease of interconnects.
  • first and/or second layers are dimensioned in the form of an elongated spiral or 'racetrack' shape. The difference is that the new approach used round shape in the ends rather than 90 degree bends as with prior art transformers.
  • a centre tapped transformer which can be realized using elongated spiral coils with magnetic core.
  • the centre taps are also used as via plugs connecting the two layers of conductors in the transformer.
  • multilayer interleaved windings can be used to reduce the leakage inductance of a transformer with a magnetic core.
  • at least one first layer of magnetic material comprising the bottom portion of the magnetic cores of a transformer. The bottom portion of the magnetic cores at least is separated into two parts.
  • At least one second layer of magnetic material comprising the top portion of the magnetic cores of a transformer.
  • the top portion of the magnetic cores at least is separated into two parts.
  • At least one insulating layer between the first layer of magnetic material and the first layer of windings.
  • At least one insulating layer between the second layer of magnetic material and the second layer of windings.
  • the primary winding of the first layer may be connected to the primary winding of the second layer by primary winding centre pads provided in the first and the second layers and the secondary winding of the first layer may be connected to the secondary winding of the second layer by secondary winding centre pads provided in the first and the second layers.
  • the first and second layers are metal.
  • the pads are provided external to the primary and secondary windings.
  • the centre-tapped transformer has an elongated spiral shape to take advantage of anisotropic properties of magnetic material with hard axis aligned and parallel to the straight portion of windings.
  • the centre-tapped transformer has at least two magnetic cores surrounding the two straight portions of windings. The two parts of magnetic core are separated to each other with non-conductive materials or air.
  • a winding for use in a transformer, said winding comprising an elongated spiral shape.
  • the winding comprises two substantially straight opposing sides and rounded or arcuate opposing sides to define the 'racetrack' shape.
  • the centre-tapped transformer may comprise a plurality of first and second layers, wherein the windings of each first layer are connected to the corresponding windings of each second layer through centre pads provided in the first and the second layers.
  • the present invention also provides a method of fabricating a centre-tapped transformer having a primary and a secondary winding comprising the steps of: interleaving a first portion of the primary winding and a first portion of the secondary winding on a first layer of metal ;
  • the method may further comprise connecting the primary winding of the first layer to the primary winding of the second layer by primary winding centre pads provided in the first and the second layers and connecting the secondary winding of the first layer to the secondary winding of the second layer by secondary winding centre pads provided in the first and the second layers.
  • Figure 1 shows a cross section of a prior art transformer with interleaved primary and secondary windings
  • Figure 2 shows a cross section of a prior art transformer with stacked primary and secondary windings
  • Figure 3 shows a cross section of the centre-tapped transformer of the present invention
  • Figure 4 shows a top view of the first layer of the centre-tapped transformer of the present invention
  • Figure 5 shows a top view of the first and second layers of the centre- tapped transformer of the present invention
  • Figure 6 shows the magnetic field distribution over the cross section of the centre-tapped transformer of the present invention
  • Figure 7 shows the magnetic field distribution of a prior art transformer having interleaved primary and secondary windings
  • Figure 8 shows the magnetic field distribution of a prior art transformer having stacked primary and secondary windings
  • Figure 9 a one exemplar application of a centre-tapped transformer with centre taps, T1 c and T2c, connected to external circuitry;
  • Figure 10 is a conventional centre-tapped transformer using the same winding arrangement as shown in Fig. 2.
  • the present invention discloses a centre tapped transformer fabricated with spiral coils.
  • Figure 3 shows a cross section of one embodiment of the transformer structure of the present invention.
  • the bottom layer of magnetic core is separated into two portions, 300 and 305, to avoid excess eddy current losses induced by the magnetic flux perpendicular to the magnetic layer.
  • the top layer of magnetic core is also separated into two portions, 310 and 315, to avoid excess eddy current losses induced by the magnetic flux perpendicular to the magnetic layer.
  • two layers of metal stacked on top of one another are used to realize the primary and secondary windings of the transformer, and the windings are interleaved on each layer.
  • each layer contains a portion of each of the respective primary and secondary windings. Therefore, the first layer comprises a first portion of the primary winding interleaved with a first portion of the secondary winding, and the second layer comprises a second portion of the primary winding interleaved with a second portion of the secondary winding.
  • the windings are shaped to form an elongated spiral, also known as a "racetrack". This is achieved by stretching half of a circular spiral by some distance to create an elongated spiral shape.
  • the transformer winding structure can be fabricated through a number of steps.
  • step 1 a pair of interleaved primary and secondary windings is realized on one layer.
  • Figure 4 illustrates a first layer windings laid as an elongated spiral, or racetrack configuration, and a plurality of pads.
  • pad 400 is the primary winding start pad
  • pad 405 is the primary winding end pad.
  • Pad 405 also is the primary winding centre pad, being the pad which provides the connection between the portion of the primary winding on the first layer and the portion of the primary winding on the second layer.
  • pad 410 is the secondary winding start pad
  • pad 415 is the secondary winding end pad, as well as the secondary winding centre pad, being the pad which provides the connection between the portion of the secondary winding on the first layer and the portion of the secondary winding on the second layer.
  • step 2 another pair of interleaved primary and secondary windings is realized on a second layer. This second layer is then stacked or positioned on top of the first layer, as shown in Figure 5.
  • pad 520 is the primary winding centre pad, being the pad that provides for the connection between the primary winding on the second layer and the primary winding on the first layer, by connecting to centre pad 405 of the first layer
  • pad 525 is the secondary winding centre pad, being the pad that provides for the connection between the secondary winding on the second layer and the secondary winding on the first layer, by connecting to centre pad 415 of the first layer.
  • Pad 505 is the primary winding end pad, while pad 515 is the secondary winding end pad.
  • Pad 505 is the primary winding end pad, while pad 515 is the secondary winding end pad.
  • two layers of metal are used in the fabrication of the windings in a centre-tapped transformer.
  • the same structure could equally well be employed to realize multiple layers of winding structures (such as for example 4, 6, 8, or more layers), by repeatedly stacking the two-layer structure shown in Figure 5.
  • a four layer structure could be realized by the following steps:
  • step 1 a pair of interleaved primary and secondary windings is realized on one layer, in the same manner as was previously explained with reference to Figure 4.
  • step 2 another pair of interleaved primary and secondary windings is realized on a second layer and connected to the first layer in the same manner as was previously described with reference to Figure 5.
  • pad 505 is now also used to provide for the connection between that portion of the primary winding on the second layer and that portion of the primary winding on the third layer.
  • pad 515 is now also used to provide for the connection between that portion of the secondary winding on the second layer and that portion of the secondary winding on the third layer.
  • step 3 another pair of interleaved primary and secondary windings is realized on a third layer and connected to the second layer.
  • This third layer will have the same pattern of pads as that shown in Figure 4, with the exception of there being two additional pads on the third layer in order to provide the connection between the portion of the primary winding on the second layer and the portion of the primary winding on the third layer and the connection between the portion of the secondary winding on the second layer and the portion of the secondary winding on the third layer.
  • pads 400 and pad 410 are not needed.
  • this fourth layer will have the same pattern of pads as that shown in Figure 5, with pad 505 corresponding to the primary end pad and pad 515 corresponding to the secondary end pad.
  • Figures 6 to 8 enable the magnetic field distribution of the centre-tapped transformer of the present invention to be compared with the two typical prior art primary and secondary arrangements of transformer windings described in the background to the invention section.
  • Figure 6 shows a simulation of the magnetic field distribution of the centre-tapped transformer of the present invention.
  • Figure 7 a simulation of the field distribution of a transformer having interleaved primary and secondary windings is shown, while Figure 8 shows a simulation of a transformer having stacked primary and secondary windings. It will be appreciated that Finite Element Analysis can be directly transferred into leakage inductance, since the leakage inductance is proportional to the energy stored within the magnetic field.
  • Fig. 9 is a one exemplar application of a centre-tapped transformer with centre taps, T1 c and T2c, connected to external circuitry.
  • T1 a and T1 b are the two end terminals for primary winding.
  • T2a and T2b are the two end terminals for secondary winding.
  • Fig. 10 is a conventional centre-tapped transformer using the same winding arrangement as shown in Fig. 2.
  • Pad 900 corresponds to one primary end pad and pad 905 corresponding to the other primary end pad with 910 corresponds to the centre tap of primary winding.
  • Pad 920 corresponds to one secondary end pad and pad 925 corresponds to the other secondary end pad with 930 corresponding to the centre tap of secondary winding.
  • the occupied footprint area of such a structure will be considerably larger than that of the present invention. Hence, the present invention will result in a much higher inductance density.
  • centre tapped transformer of the present invention there are a number of advantages associated with the centre tapped transformer of the present invention. Firstly, by fabricating a centre tapped transformer with an elongated spiral winding, the high inductance density associated with spiral coils can be exploited.
  • the elongated shape is to take advantage of anistropic properties of magnetic material.
  • the coupling factor of transformers which is a critical parameter in evaluating the performance of a transformer, can be greatly improved through the use of this transformer structure. This is due to the fact that centre-tapped transformers have a much smaller leakage inductance when compared to conventional integrated transformers, as has been illustrated clearly with respect to Figures 6 to 8 and Fig. 10 above.
  • the transformer of the present invention provides ultra-low leakage inductance and excellent coupling.
  • the contact pads are located externally on the transformer, it enables micro-transformer arrays to be implemented with no extra interconnection requirement, and thus leads to an improvement in the flexibility in transformer design both at circuit level and component level, as well as efficiency.
  • the transformer of the present invention can also be easily realized using several standard fabrication processes, such as PCB, CMOS or MEMS.
  • the transformer can be further extended to realize a multi-layer structure through stacking.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Coils Or Transformers For Communication (AREA)
  • Coils Of Transformers For General Uses (AREA)

Abstract

La présente invention concerne un transformateur à prise médiane. Ledit transformateur comprend au moins une première couche comprenant une première partie d'un enroulement primaire entrelacée avec une première partie d'un enroulement secondaire et au moins une seconde couche comprenant une seconde partie de l'enroulement primaire entrelacée avec une seconde partie de l'enroulement secondaire. La seconde couche est disposée au-dessus de la première couche. L'enroulement primaire de la première couche est connecté à l'enroulement primaire de la seconde couche à travers le centre des première et seconde couches et l'enroulement secondaire de la première couche est connecté à l'enroulement secondaire de la seconde couche à travers le centre des première et seconde couches.
PCT/EP2015/065761 2014-07-09 2015-07-09 Transformateur à prise médiane WO2016005526A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US201462022443P 2014-07-09 2014-07-09
US62/022,443 2014-07-09
GB1415074.2A GB2529635A (en) 2014-08-26 2014-08-26 Centre-tapped transformer
GB1415074.2 2014-08-26

Publications (1)

Publication Number Publication Date
WO2016005526A1 true WO2016005526A1 (fr) 2016-01-14

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PCT/EP2015/065761 WO2016005526A1 (fr) 2014-07-09 2015-07-09 Transformateur à prise médiane

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GB (1) GB2529635A (fr)
WO (1) WO2016005526A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018186730A1 (fr) * 2017-04-03 2018-10-11 Prolec Ge Internacional, S. De R. L. De C. V. Agencement d'enroulements intercalés pour transformateurs de puissance
CN111261389A (zh) * 2018-11-30 2020-06-09 锐迪科微电子科技（上海）有限公司 复合式功率合成变压器
EP4002402A1 (fr) * 2020-11-20 2022-05-25 Analog Devices International Unlimited Company Transformateur planaire fendu symétrique

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5367760A (en) * 1993-04-26 1994-11-29 Terlop; William E. Method of making a narrow profile transformer
US5852866A (en) * 1996-04-04 1998-12-29 Robert Bosch Gmbh Process for producing microcoils and microtransformers
FR2772973A1 (fr) * 1997-12-23 1999-06-25 Sextant Avionique Bobinage pour transformateur planar
WO2005027156A2 (fr) * 2003-09-16 2005-03-24 South Bank University Enterprises Ltd. Modem de ligne d'abonne numerique et transformateur
US20110032065A1 (en) * 2009-08-07 2011-02-10 Imec Two Layer Transformer
US20110304422A1 (en) * 2010-06-10 2011-12-15 General Electric Company Transformer assembly for a magnetic resonance imaging system
JP2012169410A (ja) * 2011-02-14 2012-09-06 Tokyo Parts Ind Co Ltd コイル部品
WO2013136936A1 (fr) * 2012-03-16 2013-09-19 株式会社村田製作所 Bobine d'arrêt à mode commun
US20140176284A1 (en) * 2012-12-26 2014-06-26 Samsung Electro-Mechanics Co., Ltd. Common mode filter and method of manufacturing the same

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000277354A (ja) * 1999-03-23 2000-10-06 Nagano Japan Radio Co 積層型コモンモードチョークコイル
JP2006086460A (ja) * 2004-09-17 2006-03-30 Alps Electric Co Ltd 結合コイル
TWI238515B (en) * 2004-10-08 2005-08-21 Winbond Electronics Corp Integrated transformer with stack structure

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5367760A (en) * 1993-04-26 1994-11-29 Terlop; William E. Method of making a narrow profile transformer
US5852866A (en) * 1996-04-04 1998-12-29 Robert Bosch Gmbh Process for producing microcoils and microtransformers
FR2772973A1 (fr) * 1997-12-23 1999-06-25 Sextant Avionique Bobinage pour transformateur planar
WO2005027156A2 (fr) * 2003-09-16 2005-03-24 South Bank University Enterprises Ltd. Modem de ligne d'abonne numerique et transformateur
US20110032065A1 (en) * 2009-08-07 2011-02-10 Imec Two Layer Transformer
US20110304422A1 (en) * 2010-06-10 2011-12-15 General Electric Company Transformer assembly for a magnetic resonance imaging system
JP2012169410A (ja) * 2011-02-14 2012-09-06 Tokyo Parts Ind Co Ltd コイル部品
WO2013136936A1 (fr) * 2012-03-16 2013-09-19 株式会社村田製作所 Bobine d'arrêt à mode commun
US20140176284A1 (en) * 2012-12-26 2014-06-26 Samsung Electro-Mechanics Co., Ltd. Common mode filter and method of manufacturing the same

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018186730A1 (fr) * 2017-04-03 2018-10-11 Prolec Ge Internacional, S. De R. L. De C. V. Agencement d'enroulements intercalés pour transformateurs de puissance
US11450473B2 (en) 2017-04-03 2022-09-20 Prolec Ge Internacional, S. De. R. L. De C.V. Arrangement of interleaved windings for power transformers
CN111261389A (zh) * 2018-11-30 2020-06-09 锐迪科微电子科技（上海）有限公司 复合式功率合成变压器
EP4002402A1 (fr) * 2020-11-20 2022-05-25 Analog Devices International Unlimited Company Transformateur planaire fendu symétrique
US11631523B2 (en) 2020-11-20 2023-04-18 Analog Devices International Unlimited Company Symmetric split planar transformer

Also Published As

Publication number Publication date
GB201415074D0 (en) 2014-10-08
GB2529635A (en) 2016-03-02

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