WO2009008740A1 - Transformateur - Google Patents

Transformateur Download PDF

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Publication number
WO2009008740A1
WO2009008740A1 PCT/NZ2008/000134 NZ2008000134W WO2009008740A1 WO 2009008740 A1 WO2009008740 A1 WO 2009008740A1 NZ 2008000134 W NZ2008000134 W NZ 2008000134W WO 2009008740 A1 WO2009008740 A1 WO 2009008740A1
Authority
WO
WIPO (PCT)
Prior art keywords
turns
voltage winding
low voltage
section
sections
Prior art date
Application number
PCT/NZ2008/000134
Other languages
English (en)
Inventor
Christopher William Fotherby
Original Assignee
Power Concepts Nz Limited
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 Power Concepts Nz Limited filed Critical Power Concepts Nz Limited
Publication of WO2009008740A1 publication Critical patent/WO2009008740A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F30/00—Fixed transformers not covered by group H01F19/00
    • H01F30/06—Fixed transformers not covered by group H01F19/00 characterised by the structure
    • H01F30/16—Toroidal transformers
    • 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
    • H01F27/06—Mounting, supporting or suspending transformers, reactors or choke coils not being of the signal type
    • H01F2027/065—Mounting on printed circuit boards
    • 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
    • H01F27/26—Fastening parts of the core together; Fastening or mounting the core on casing or support
    • H01F27/266—Fastening or mounting the core on casing or support
    • 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
    • H01F27/2895—Windings disposed upon ring 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
    • H01F27/30—Fastening or clamping coils, windings, or parts thereof together; Fastening or mounting coils or windings on core, casing, or other support
    • H01F27/306—Fastening or mounting coils or windings on core, casing or other support
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F3/00—Cores, Yokes, or armatures
    • H01F3/10—Composite arrangements of magnetic circuits
    • H01F3/14—Constrictions; Gaps, e.g. air-gaps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F5/00—Coils
    • H01F5/04—Arrangements of electric connections to coils, e.g. leads

Definitions

  • the present invention relates to a low leakage inductance transformer for installation on a printed • circuit board (PCB).
  • PCB printed • circuit board
  • Transformers couple AC power from a first winding to a second winding. Many transformers are wound on a core of magnetic material. Transformers can be used in a wide range of applications, for a range of current, voltage and power magnitudes at a range of frequencies.
  • a high-frequency transformer could be used in a DC to AC inverter, as part of a circuit that steps up a DC voltage to a higher DC voltage, which is in turn converted to an AC voltage by other circuitry. This is just one example.
  • Circuits such as DC to AC inverters are limited in their power transfer capabilities based on the transformer characteristics. Often the maximum power transfer capability of a transformer is limited by its leakage inductance, or the leakage inductance causes an undesirable reduction in the transformer output voltage.
  • the present invention may be said to consist in a transformer comprising: a core with a closed loop topology, a low voltage winding around the core comprising: two or more sections, each section comprising one or more turns and a first termination and a second termination such that the • sections are electrically connectable in parallel, wherein each section of the low voltage winding has the same number of turns and the low voltage winding has an effective number of turns when the sections are connected in parallel which is the number of turns in each section, a high voltage winding around the core comprising one or more sections, each section comprising one or more turns and a first termination and a second termination, the high voltage winding having an effective number of turns, wherein the effective number of turns of the low voltage winding and the effective number of turns of the high voltage winding results in a desired turns ratio for the transformer, and wherein the total number of turns of the sections of the low voltage wind
  • the total number of turns of the sections of the low voltage winding differs from the total number of turns of the one or more sections of the high voltage winding by five or less, and preferably two or less.
  • the number of turns in each section of the low voltage winding is the number of turns in each section of the high voltage winding divided by the desired turns ratio.
  • the core comprises an air gap to define the magnetisation inductance to a desired value.
  • the core comprises two or more air gaps to define the magnetisation inductance to a desired value.
  • each section of the low voltage winding has a first termination and a second termination and wherein the sections of the low voltage winding are arranged adjacent each other around the core, such that the first termination of any section is proximate or adjacent the second termination of an adjacent section.
  • the first terminations of each section of the low voltage winding are connected to a first conductive plane and the second terminations of each section of the low voltage winding are connected to a second conductive plane.
  • one termination of each section is connected to a respective conductive plane using a guiding terminal that enables that termination to reside adjacent or proximate another termination of an adjacent section connected to another respective conductive plane.
  • the present invention may be said to consist in a transformer comprising: a core with a closed loop topology, a low voltage winding with two or more sections, a high voltage winding with the same or similar number of turns and one or more sections, wherein the low voltage and high voltage windings have a turns ratio dependent on the effective number of turns of each winding.
  • the core is toroidal or substantially toroidal.
  • Figure 1 is a schematic perspective view of a transformer according to one embodiment
  • Figure 2 is a schematic elevation view of the transformer showing its connection to a PCB
  • Figure 3 is a schematic cross-section view of the transformer showing its connection to a PCB
  • Figure 4a is a schematic perspective view of the transformer core with a single air gap
  • Figure 4b is a schematic perspective view of the transformer core with a double air gap
  • Figure 5a is a schematic plan view of the transformer
  • Figure 5b is a schematic plan view of a transformer according to another embodiment
  • Figure 6 is a ckcuit diagram of a DC to AC inverter in which the transformer could be used.
  • PCBs are used to construct power electronic circuits, such as those for DC to AC inverters, it is still necessary to use transformers. It is desirable to include these transformers on the PCB, although this is difficult due to the bulky nature of transformers. When the transformer is not mounted on the PCB, or even when it is, undesirable leakage inductance can limit the power transfer capability of the circuit.
  • the present invention assists in reducing leakage inductance when using transformers on PCBs, for PCBs used with surface mounted components, or PCBs used with leaded components, or PCBs used with a combination of these two types of components. For circuits constructed completely or partially with surface mount components, the PCB is often the main mechanical element of the circuit, so that it is simpler to assemble the circuit into a complete product if the transformer is mounted on the PCB along with the rest of the ckcuit.
  • Embodiments described herein provide a way of putting a high power low leakage inductance transformer on a PCB.
  • the transformer comprises an equal (or almost equal) total (actual) number of primary and secondary turns tightly interleaved to reduce leakage inductance.
  • each winding can be made of two or more winding sections connected in parallel (or series) as requited. Each winding section results in an effective number of turns, being the number of turns in that winding section.
  • the turns ratio of the transformer is the result of the ratio of the effective number of turns of the primary and secondary windings.
  • both the primary and secondary windings can have an equal number of total ⁇ turns to enable low leakage inductance, while still providing the requked turns ratio.
  • Terminals for .each winding or section of winding are also arranged in a manner to reduce leakage inductance, and the transformer is mounted on a PCB in a manner to reduce leakage inductance.
  • Figures 1 and 5a show a transformer 1 according to one embodiment of the invention.
  • the transformer comprises a core 201 with an aperture to form a closed loop.
  • the closed loop core is toroidal or substantially toroidal in shape, although other options are possible. For example, it could be an irregular shape with an aperture, or have a straight sided ckcumference such that the plan cross-section is a polygon.
  • the core 201 could be made from ferrite or any other suitable material.
  • a high voltage winding 230 is wound as a single layer atound the entire loop of the core 201.
  • Figures 1 and 5a shows a high voltage winding 230 that is a single section.
  • the high voltage winding 230 has two terminals 202, 203 that almost meet and extend from the core 201.
  • the high voltage winding could be alternatively split into more than one section, each section having the same number of turns and connected or connectable in parallel.
  • a single section of 54 turns for a 230V inverter could be provided, or alternatively two sections each of 27 turns connected or connectable in parallel for a ll 5V inverter.
  • a multi-section high voltage winding will be described further in relation to Figure 5. '
  • a low voltage winding (shown generally as 231) is wound around the entire loop of the core 201.
  • the low voltage winding 231 has the same total number of turns as the high voltage winding 230.
  • the low voltage winding 231 is divided into two or more winding sections e.g. 232, 233 connected or connectable in parallel. Each winding section has the same number of turns.
  • a 24VDC to 230VAC inverter transformer has a high voltage winding of one section of 54 turns and a low voltage winding of 18 sections of three turns each.
  • the number of turns in each section of the low voltage winding equals the number of turns in each section of the high voltage winding divided by the desired turns ratio. This holds if there is one, or multiple high voltage winding sections.
  • Figure 1 only shows a portion of the high and low voltage windings.
  • the windings actually extend around the whole circumference of the core.
  • the turns in Figure 1 are shown further apart than in practice, also for clarity.
  • the low voltage 231 and high voltage 230 windings both have a total number of turns. This is the total number of turns of all the sections of the respective winding added together.
  • the effective number of turns of the low voltage 231 or high voltage 230 winding is the number of turns in one parallel connected or connectable section of that winding. For example, low voltage winding section 232 has three turns, resulting in an effective number of turns of three. If the high voltage winding has just one section, then the effective number of turns is the total number of turns of the winding. If the high voltage winding has more than one section connected or connectable in parallel, the effective number of turns is the number of turns of one of the sections. The effective number of turns is the number that is used to determine the turns ratio of the transformer.
  • the low voltage 231 and high voltage 230 windings can use Litz wire for good high frequency performance, or any other suitable wire. Double or triple insulated wire can be used to give supplementary or reinforced insulation. The low voltage winding does not necessarily need double or triple insulation.
  • the turns of the low voltage winding 231 are, as much as is possible, interleaved between the turns of the high voltage winding 230.
  • the low voltage winding 231 is wound such that around the outside circumference of the core, the high voltage winding 230 turns and low voltage winding 231 turns interleave with minimal gap between them.
  • the gap between adjacent high voltage turns is not big enough to let a low voltage winding turn fully interleave between them. Instead each low voltage turn sits in the indentation between two adjacent high voltage turns (see Figures 5a, 5b). It will be appreciated that if the gap between high voltage turns is not sufficient on the outside circumference, then the low voltage turns might not sit fully between the high voltage turns, but rather sit in the indent between turns.
  • each section e.g. adjacent sections 232 and 233 of the low voltage winding 231 has the same number of turns, and each section has a first e.g. 204, 206 and second e.g. 205, 207 termination.
  • the corresponding first terminations 204, 206 and corresponding second terminations 205, 207 of each section 232, 233 have current running through them in the same direction for each section. So, all first terminations have current flowing in the same direction as each other, and all second terminations have current flowing in the same direction as each other.
  • the currents flowing in all first terminations and the currents flowing in all second terminations are in opposite directions.
  • each of the sections are arranged adjacently around the core 201, so that each high voltage winding 230 turn is interleaved by a turn from one of the sections of the low voltage winding 231. Note, on the inside of the core, each turn of the low voltage winding sections might actual sit in the indent between two high voltage winding turns.
  • the term "interleave" can be generally used to mean both these occurrences.
  • the first terminations e.g. 204, 206 of the low voltage sections are electrically connected together or can be electrically connected together.
  • the second terminations e.g. 205, 207 of the low voltage sections are electrically connected or can be electrically connected together. This provides the parallel connection of the sections. This could be done by conductive planes on a PCB. Generally, before the transformer is installed on a PCB, the terminations (and therefore sections) remain unconnected.
  • the low voltage winding sections e.g. 232, 233 are wound adjacently onto the core 201 such that the first termination e.g. 206 of a low voltage section is proximate or adjacent the second termination e.g. 205 of an adjacent low voltage section.
  • the transformer mounts on a printed circuit board (PCB) 210 with at least two conductive layers, preferably with plated through holes and slots. Under the transformer 1 and in its immediate vicinity one of the layers is used to connect the first terminations (e.g. 206) of all the low voltage sections. The other layer is used to connect to the second terminations (e.g. 205) of all the low voltage sections. This connects all the sections in parallel. Both layers are in the form of substantially uninterrupted sheets. Minor interruptions will occur where holes or slots have been formed in the PCB to receive the ends of the low voltage sections, and for other purposes, e.g. PCB mounting holes.
  • PCB printed circuit board
  • the first termination 206 of one low voltage winding section 233 is as close as possible to the second termination 205 of an adjacent section 232.
  • Figure 2 shows a section of Figure 1.
  • the connection point for the second termination 205 of one low voltage section 232 to the PCB should be as close as possible to the connection point of the PCB for the first termination 206 of the adjacent low voltage section 233. This reduces the termination inductance as a result of the currents in the first termination 206 and the second termination 205 flowing in close proximity and in opposite directions. This is the same for the first termination and second termination pairs for all winding sections.
  • connection points can be located anywhere under the core 201 from the inside circumference to the outside circumference, but is easier to solder the terminations to the PCB 210 if the connections are located at the outside circumference. If this is the case then one termination e.g. 206 and associated terminating wire will rise perpendicularly from die PCB 210 past the outside circumference of the core 201 and wrap over the top of the core before going down the inside circumference.
  • the termination 205 and associated terminating wire connection to the adjacent low voltage section will make a right angled bend where it is connected to the PCB 210 and immediately head underneath the core.
  • a guiding terminal 214 such as a tag soldered to the terminating wite.
  • the terminal has a tubular section to accept the wire and the tube has a radial extension that fits into a slot in the PCB 210. This positions the wire parallel to the PCB 210 in the correct orientation to head under the core 201.
  • an air gap can be included in the magnetic circuit of the transformer core.
  • the length of the gap will determine the magnetisation inductance, so it can be altered to define the magnetisation inductance to the desired value.
  • a longer gap results in less magnetisation inductance.
  • a single air gap 240 could be made, for example by a single cut in the core 201.
  • multiple air gaps 241, 242 are possible, for example by multiple cuts (see Figure 4b).
  • a core made from ferrite could be very brittle.
  • the core could be cut completely in half as shown in Figure 4b, and tape put on one or more of the cut faces so that the total thickness of tape equals the length of gap required, and then the two halves fixed together by wrapping tape around the outside circumference.
  • a physical air gap is not essential. Any material with a magnetic permeability similar to that of air can be used.
  • further cuts could be made to produce a core of three or more pieces.
  • Figure 5b shows a plan view of a second embodiment of the transformer. This is similar to the first embodiment, except that the transformer has a high voltage winding in two sections with terminations 245, 246, 247, 248. T f his is illustrative, and even more sections are possible. Each section has a first e.g. 245, 247 and second termination e.g. 246, 248. The corresponding first terminations and corresponding second terminations of each section have current running through them in the same direction for each section. So, all first terminations have current flowing in the same direction as each other, and all second terminations have current flowing in the same direction as each other. The currents flowing all in all first terminations and the currents flowing in all second terminations are in opposite directions. Each of the sections is arranged adjacently around the core.
  • the first terminations 245, 247 of the high voltage sections are electrically connected 249 together or can be electrically connected together.
  • the second terminations 246, 248 of the high voltage sections are electrically connected 250 or can be electrically connected together. More particularly, termination 245 is a first end of a first high voltage section, termination 246 is a second end of a second high voltage winding, termination 247 is a first end of a second high voltage section, termination 248 is a second end of a first high voltage section, termination 249 is a parallel connection of the first ends, and termination 250 is a parallel connection of the second ends. This provides the parallel connection of the sections.
  • the terminations (and therefore sections) remain unconnected.
  • the terminations can be connected to the PCB in any suitable manner.
  • the effective number of turns is the number of turns in each section.
  • the total number of turns is the total number of turns of all sections.
  • Figures 5a, 5b show how the turns of the low and high voltage windings are interleaved on the outer circumference of the core, and how the low voltage winding turns sit in the indent of the high voltage winding turns on the inner circumference.
  • Figures 5a, 5b show the turns all the way around the core.
  • Figure 5a is a plan (top) view of a transformer with a single high voltage winding of 54 turns and with a low voltage winding of 18 sections with 3 turns each, the turns ratio being 18 to 1.
  • Figure 5b has two high voltage sections of 27 turns each.
  • the low voltage winding is 18 sections of 3 turns each, giving a turns ratio of 9 to 1.
  • the transformer embodiments describe above preferably provide one or more of: a large turns ratio, low leakage inductance, selectable magnetisation inductance, a means of making a high current - low inductance connection from the low voltage winding to a printed circuit board. It might also provide either supplementary or reinforced insulation between primary and secondary in order to meet electrical safety regulations.
  • the interleaving of the low voltage and high voltage windings provides low leakage inductance.
  • the total number of turns of the low and high voltage windings are the same so that each turn is interleaved, and no turn is left on its own on the core. This reduces leakage inductance.
  • useful gains might still be possible where the total number of turns in the low and high voltage windings does not differ substantially or significantly. For example, useful characteristics might still be gained if the total number of turns of one winding is within five of the total number of turns of the other winding. More preferably, the total number of turns of one winding is within two of the total number of turns of the other winding. For every increasing difference in the total number of turns, the leakage inductance will increase.
  • Splitting the windings into sections enables the attainment of the required number of effective turns for the desired turns ratio, while still having the required total number of turns.
  • Splitting the high voltage winding into two or more sections might be used where a single high voltage winding would result in the wire diameter being too large and the wire being too • inflexible to wrap around the core.
  • Useful gains can also be obtained where the primary and secondary windings do not completely cover the core, such that there is a gap through which the core is visible through the windings.
  • connection of the terminations close together on the PCB also assists in keeping the turns interleaved as much as possible on the bottom side of the core, thus helping to lower leakage inductance and termination inductance.
  • the air gaps also assist by defining the magnetisation inductance.
  • the low voltage and high voltage turns could fully interleave on the inside circumference of the core and interleave spaced slightly apart on the outside circumference of the core.
  • FIG. 6 shows a DC to AC inverter 600 in which the transformer could be used.
  • the transformer would increase the maximum power transfer capability and improve the efficiency of the inverter.
  • the inverter comprises a DC to DC converter 601 with a low voltage side and a high voltage side coupled by a transformer 602 (as per one of the embodiments described above), a pulse width modulator 603, and an output filter 604.
  • the workings ' of such an inverter would be known to those skilled in the art.

Landscapes

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

Abstract

L'invention concerne un transformateur (1) comprenant : un noyau présentant une topologie en boucle fermée (201), un enroulement basse tension (231) pourvu d'au moins deux sections (232, 233), un enroulement haute tension (230) ayant le même nombre de tours et une ou plusieurs sections, les enroulements basse tension (231) et haute tension (230) ayant un rapport de tours dépendant du nombre effectif de tours de chacun d'eux (231, 230).
PCT/NZ2008/000134 2007-07-09 2008-06-09 Transformateur WO2009008740A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NZ556440 2007-07-09
NZ55644007 2007-07-09

Publications (1)

Publication Number Publication Date
WO2009008740A1 true WO2009008740A1 (fr) 2009-01-15

Family

ID=40228783

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NZ2008/000134 WO2009008740A1 (fr) 2007-07-09 2008-06-09 Transformateur

Country Status (1)

Country Link
WO (1) WO2009008740A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102360858A (zh) * 2011-10-26 2012-02-22 宁波中策亿特电子有限公司 一种环形铁芯变压器及生产方法
CN102360862A (zh) * 2011-10-26 2012-02-22 宁波中策亿特电子有限公司 大功率环形变压器
CN102360861A (zh) * 2011-10-26 2012-02-22 宁波中策亿特电子有限公司 一种防漏磁环形变压器
CN111029132A (zh) * 2019-12-30 2020-04-17 肥东凯利电子科技有限公司 一种大功率高频变压器的绕线方法
EP3817019A1 (fr) * 2019-11-01 2021-05-05 Hamilton Sundstrand Corporation Transformateurs, convertisseurs de puissance dotés de transformateurs, et procédés de conversion d'énergie électrique
CN114270458A (zh) * 2020-07-06 2022-04-01 华为数字能源技术有限公司 一种矩阵变压器、功率变换器和矩阵变压器绕组的排布方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3895335A (en) * 1974-06-03 1975-07-15 Gen Electric Series/parallel connected single phase power transformer
US5543773A (en) * 1990-09-07 1996-08-06 Electrotech Instruments Limited Transformers and coupled inductors with optimum interleaving of windings

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3895335A (en) * 1974-06-03 1975-07-15 Gen Electric Series/parallel connected single phase power transformer
US5543773A (en) * 1990-09-07 1996-08-06 Electrotech Instruments Limited Transformers and coupled inductors with optimum interleaving of windings

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102360858A (zh) * 2011-10-26 2012-02-22 宁波中策亿特电子有限公司 一种环形铁芯变压器及生产方法
CN102360862A (zh) * 2011-10-26 2012-02-22 宁波中策亿特电子有限公司 大功率环形变压器
CN102360861A (zh) * 2011-10-26 2012-02-22 宁波中策亿特电子有限公司 一种防漏磁环形变压器
EP3817019A1 (fr) * 2019-11-01 2021-05-05 Hamilton Sundstrand Corporation Transformateurs, convertisseurs de puissance dotés de transformateurs, et procédés de conversion d'énergie électrique
US11217386B2 (en) 2019-11-01 2022-01-04 Hamilton Sundstrand Corporation Transformers, power converters having tranformers, and methods of converting electrical power
CN111029132A (zh) * 2019-12-30 2020-04-17 肥东凯利电子科技有限公司 一种大功率高频变压器的绕线方法
CN111029132B (zh) * 2019-12-30 2022-03-22 广州市凯辉电子有限公司 一种大功率高频变压器的绕线方法
CN114270458A (zh) * 2020-07-06 2022-04-01 华为数字能源技术有限公司 一种矩阵变压器、功率变换器和矩阵变压器绕组的排布方法

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