WO2016071123A1 - Resonant converter - Google Patents

Resonant converter Download PDF

Info

Publication number
WO2016071123A1
WO2016071123A1 PCT/EP2015/074587 EP2015074587W WO2016071123A1 WO 2016071123 A1 WO2016071123 A1 WO 2016071123A1 EP 2015074587 W EP2015074587 W EP 2015074587W WO 2016071123 A1 WO2016071123 A1 WO 2016071123A1
Authority
WO
WIPO (PCT)
Prior art keywords
distance
secondary winding
isolation
larger
winding
Prior art date
Application number
PCT/EP2015/074587
Other languages
French (fr)
Inventor
Bernd Ackermann
Peter Luerkens
Albert GARCIA TORMO
Original Assignee
Koninklijke Philips N.V.
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 Koninklijke Philips N.V. filed Critical Koninklijke Philips N.V.
Publication of WO2016071123A1 publication Critical patent/WO2016071123A1/en

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
    • H01F27/32—Insulating of coils, windings, or parts thereof
    • H01F27/324—Insulation between coil and core, between different winding sections, around the coil; Other insulation structures
    • H01F27/325—Coil bobbins
    • 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
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/28—Coils; Windings; Conductive connections
    • H01F27/32—Insulating of coils, windings, or parts thereof
    • 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
    • H01F30/10—Single-phase transformers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F5/00—Coils
    • H01F5/02—Coils wound on non-magnetic supports, e.g. formers
    • H01F2005/022—Coils wound on non-magnetic supports, e.g. formers wound on formers with several winding chambers separated by flanges, e.g. for high voltage applications
    • 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
    • H01F27/02—Casings

Definitions

  • the present invention relates to a resonant converter comprising a high voltage transformer with compact secondary windings for resonant conversion and comprising a resonant tank.
  • the present invention also relates to a method for producing such a resonant converter.
  • Resonant converters used as high voltage generators usually comprise both a high voltage transformer and an inductor in the resonant tank of the converter.
  • EP 2,560,175 Al describes a high-frequency transformer including a plurality of cores having a central leg, the cores being arranged to form core windows that are separated by the central legs.
  • a primary winding has a predetermined length of electrically conductive wire that is wound about the central legs and extends through each of the core windows.
  • WO 87/05148 Al describes a high voltage transformer.
  • An aspect of the present invention relates to a resonant converter comprising a high voltage transformer for resonant conversion and a resonant tank, the high voltage transformer comprising: a soft- magnetic core; a primary winding; and a secondary winding, which is arranged such that an axial isolation-distance spacing the secondary winding from the soft-magnetic core in an axial direction is larger than a first radial isolation-distance spacing the secondary winding from the soft-magnetic core in a radial direction or larger than a second radial isolation-distance spacing the secondary winding from the primary winding in the radial direction; and wherein the secondary winding is thereby configured to provide leakage inductance for the resonant tank coupled to the high voltage transformer.
  • the secondary winding is arranged such that an axial isolation- distance spacing the secondary winding from the soft-magnetic core in an axial direction is either larger than a first radial isolation-distance spacing the secondary winding from the soft-magnetic core in a radial direction or larger than a second radial isolation-distance spacing the secondary winding from the primary winding in the radial direction.
  • high voltage may refer to a electrical voltage above a particular threshold, for instance above 1000 V or above 2500 V or above 5000 V or above 8000 V. High voltage may be used in electrical power distribution, in cathode ray tubes, to generate X-rays and particle beams, to demonstrate arcing, for ignition, lighting, in photomultiplier tubes, and in high power amplifier vacuum tubes and further applications.
  • the high voltage transformer according to the present invention may also be used for switched-mode power supplies, including resonant converters, further also for non- resonant hard- switching DC-DC converters with galvanic isolation, wherein the magnetizing inductance may be used as main inductor.
  • the leakage inductance of the transformer when the transformer may be operated at sufficiently high frequencies, the leakage inductance of the transformer may be any suitable leakage inductance
  • the present invention may advantageously allow eliminating the resonant tank inductor which can be almost as bulky and heavy as the high voltage transformer.
  • the present invention may advantageously provide an adjusting or controlling of the leakage inductance by varying the axial length of the secondary winding.
  • the leakage inductance can be increased when the secondary winding is made more compact by reducing its axial length. This will result in the isolation- distance between secondary winding and primary winding or core being significantly larger on the top and bottom of the secondary winding than on its sides, for instance the radial sides.
  • axial length as used by the present invention may refer to the length of the secondary winding, i.e. its dimension parallel to the primary winding.
  • primary winding as used by the present invention may refer to a coil forming the part of an electrical circuit such that changing current in it induces a current in a neighboring circuit. In other words, a current through the primary coil induces current in the secondary coil, thereby it may be defined what the term “secondary winding” as used by the present invention refers to.
  • leakage inductance may refer to the electrical property of an imperfectly-coupled transformer whereby each winding behaves next to its function as a transformer winding also as a self-inductance constant in series with the winding's respective ohmic resistance constant.
  • a method for producing a high voltage transformer comprising the steps of:
  • a soft-magnetic core, a primary winding, and a secondary winding arranging the secondary winding in such a way that an axial isolation-distance spacing the secondary winding from the soft-magnetic core in an axial direction is larger than a first radial isolation- distance spacing the secondary winding from the soft-magnetic core in radial direction and providing an inductance for a resonant tank coupled to the high voltage transformer by adjusting a ratio of the axial isolation-distance and the first radial isolation-distance.
  • the axial isolation-distance is larger than 1.2 times or larger than 1.5 times or larger than 2.0 times or larger than 5.0 times the first radial isolation-distance. This advantageously allows precisely adjusting the leakage inductance provided.
  • the secondary winding is arranged such that the axial isolation-distance spacing the secondary winding from the soft-magnetic core in the axial direction is larger than a second radial isolation-distance spacing the secondary winding from the primary winding in the radial direction, providing inductance for a resonant tank coupled to the high voltage transformer.
  • the axial isolation-distance is larger than 1.2 times or larger than 1.5 times or larger than 2.0 times or larger than 5.0 times the second radial isolation-distance. This advantageously allows reducing the amount of external inductance needed.
  • the high voltage transformer is configured to provide an output voltage of up to 5 kV or preferably of up to 25 kV or particularly preferred of up to 80 kV. This advantageously providing suffiently high output voltages.
  • this advantageously allows reaching a high voltage of 140kV after a four-stage cascade, if 35kV are provided as output voltage of the high voltage transformer.
  • a secondary axial length of the secondary winding is smaller than 0.5 times a primary axial length of the primary winding.
  • the high voltage transformer is configured to provide as the inductance for a resonant tank coupled to the high voltage transformer a leakage inductance of up to 2 ⁇ or of up to 5 ⁇ or of up to 10 ⁇ .
  • a resonant converter comprising a resonant tank and a high voltage transformer according to the first aspect of the present invention or according to any implementation form of the first aspect.
  • the resonant tank is configured to at least partially replace a resonance tank inductance by the provided inductance of the high voltage transformer. This advantageously allows reducing the number of electronic components or the space need for integration of the electronic components.
  • the primary winding and/or the secondary winding are build in a slot winding or in a single layer winding or in a double layer winding or in any other kind of layer winding or in distributed layer winding.
  • a medical system comprising a resonant converter according to the previous aspect of the present invention or according to any implementation form of the previous aspect of the present invention.
  • Fig. 1 shows a schematic diagram of a resonant converter for explaining the present invention
  • Fig. 2 shows a schematic diagram of a high voltage transformer for explaining the present invention
  • Fig. 3 shows a schematic diagram of a high voltage transformer for explaining the present invention
  • Fig. 4 shows a schematic diagram of a high voltage transformer according to an exemplary embodiment of the present invention
  • Fig. 5 shows a schematic diagram of a high voltage transformer according to an exemplary embodiment of the present invention
  • Fig. 6 shows a schematic diagram of a medical imaging system according to an exemplary embodiment of the present invention
  • Fig. 7 shows a schematic diagram of a flow-chart of a method for producing a high voltage transformer according to an exemplary embodiment of the present invention.
  • Fig. 8 shows a schematic diagram of leakage inductances measured for different configurations of the secondary winding of the transformer according to an exemplary embodiment of the present invention.
  • Figure 1 shows a schematic diagram of a resonant converter used as high voltage generator according to an exemplary embodiment of the present invention.
  • the resonant converter 200 may comprise a resonant tank 150 and the high voltage transformer 100.
  • the resonant tank 150 may comprise a resonant tank inductance 150-1 which may be at least partially replaced by the provided leakage inductance of the high voltage transformer 100.
  • the resonant converter 200 may further comprise an inverter circuit 210 and a voltage multiplier circuit 220.
  • the high voltage transformer 100 when the high voltage transformer 100 may be operated at high frequencies, then it may be of interest to use the leakage inductance of the high voltage transformer 100 as inductance or the tank inductance 150-1 in the resonant tank 150 connected to the low voltage side of the high voltage transformer 100. This may at least partially eliminate the resonant tank inductance 150-1 which can be almost as bulky and heavy as the high voltage transformer 100, if no further inductance is provided.
  • the voltage multiplier 220 circuit may supply an X-ray tube 410.
  • Figure 2 shows a schematic diagram of a high voltage transformer for explaining the present invention.
  • the secondary winding 20 of the high voltage transformer 100 may spread along its winding length, vertical axis in Figure 2.
  • the distance between the secondary winding 20, and the soft-magnetic core 30 of the high voltage transformer 100 and the primary winding 10 of the high voltage transformer 100 is almost constant.
  • Such a design of the high voltage transformer 100 provides low losses and low leakage inductance.
  • Figure 3 shows a schematic diagram of a high voltage transformer with almost constant distance between the secondary winding 20 and the primary winding 10 or between the secondary winding 20 and the core 30.
  • the secondary winding 20 as shown in Figure 3 may be modified as far as the number of winding turns per slot of the secondary winding 20 is concerned.
  • the standard construction of a winding of the high voltage transformer 100 comprises a sequence of wide slots for taking up winding turns and narrow slots for returning the wire from the top of one neighboring wide slot to the bottom of the other neighboring wide slot.
  • the sequence of wide slots and narrow slots is alternating coming from the outside.
  • the wire enters a wide slot at its bottom, multiple turns are wound in the wide slot until it is filled; then the wire leaves the wide slot at its top, enters the adjacent narrow slot, is guided from the top of the narrow slot to the bottom of the narrow slot, and then leaves the narrow slot while entering the next wide slot and so on.
  • this sequence may be repeated multiple times until at the end the wire leaves a wide slot at its top and then goes to the outside.
  • the number of winding turns per winding slot of the secondary winding 20 of the high voltage transformer 100 may be varied from winding slot to winding slot, resulting in a non-equal distribution of the number of winding turns per winding slot of the secondary winding 20.
  • the number of winding turns per winding slot of the primary winding 10 may be varied from winding slot to winding slot, resulting in a non-equal distribution of the number of winding turns per winding slot of the primary winding 10.
  • Figure 4 shows a schematic diagram of a high voltage transformer according to an exemplary embodiment of the present invention.
  • the secondary winding 20 of the high voltage transformer 100 is such arranged that an axial isolation-distance D2 spacing the secondary winding 20 from the soft-magnetic core 30 in an axial direction DA is larger than a first radial isolation-distance Dl spacing the secondary winding 20 from the soft-magnetic core 30 in a radial direction DR.
  • the secondary winding 20 of the high voltage transformer 100 may be configured to provide a resonant tank inductance 150-1 for a resonant tank 150 coupled to the high voltage transformer 100.
  • the secondary winding 20 of the high voltage transformer 100 may be arranged such that the axial isolation-distance D2 spacing the secondary winding 20 from the soft- magnetic core 30 in the axial direction DA is larger than a second radial isolation-distance D3 spacing the secondary winding 20 from the primary winding 10 in the radial direction DR, providing inductance for a resonant tank 150 coupled to the high voltage transformer 100.
  • a high voltage transformer 100 is provided, wherein the distance between the top and bottom of the high voltage transformer and the soft-magnetic core is significantly larger than the distance between its inside and the primary winding and the distance between its outside and the core.
  • the distance between the top and bottom of the secondary winding and the core will be considerably larger than the distance between its inside and the primary winding or the distance between its outside and the core.
  • the axial isolation-distance D2 is larger than 1.2 times the first radial isolation-distance Dl .
  • the leakage inductance can be adjusted by varying the axial length 20-1 of the secondary winding 20 of the high voltage transformer 100.
  • the soft- magnetic core 30 may be for instance a soft magnetic EC 123 ferrite core with a width of 123 mm, a height of 108 mm, and a depth of 30 mm.
  • the soft- magnetic core 30 may have a round centre leg with 30 mm diameter and the cross section of the winding area is 34 mm wide and 82 mm high.
  • the primary winding 10 of the high voltage transformer 100 may comprise 8 turns of two parallel 1700*0.071 Litz wires.
  • the secondary winding 20 of the high voltage transformer 100 may comprise 120 turns of 250*0.071 Litz wire, resulting in a leakage inductance of 2.12 ⁇ and a magnetizing inductance of 559 ⁇ .
  • the axial length of the secondary winding may be reduced by 10 % or by 20 % with respect to equally extended primary windings and secondary winding, resulting in an increase of the leakage inductance by 16%.
  • the high voltage transformer 100 may be a closed-core transformer and may be constructed in 'core form' or 'shell form'. When windings surround the core, the transformer is core form; when windings are surrounded by the core, the transformer is shell form.
  • both axial isolation-distances D2 of the high voltage transformer 100 spacing the secondary winding 20 from the soft-magnetic core 30, e.g. the top and the bottom axial isolation-distances D2, have the same length.
  • the top axial isolation- distance D2 spacing the secondary winding 20 from the soft-magnetic core 30 at the upper part or the bottom axial isolation-distance D2 spacing the secondary winding 20 from the soft-magnetic core 30 at the lower part of the high voltage transformer is larger than a first radial isolation-distance Dl spacing the secondary winding 20 from the soft-magnetic core 30 in a radial direction DR.
  • the number of winding turns per winding slot of the primary winding 10 and/or the secondary winding 20 may be varied from winding slot to winding slot of the primary winding 10 and/or the secondary winding 20, respectively.
  • two different axial isolation-distances D2 at the upper part and the bottom part of the high voltage transformer spacing the secondary winding 20 from the soft- magnetic core 30 may be used.
  • FIG. 5 shows a schematic diagram of a high voltage transformer according to an exemplary embodiment of the present invention.
  • the high voltage transformer 100 may comprise a primary winding 10, a secondary winding 20, and a soft- magnetic core 30.
  • Figure 6 shows a schematic diagram of a medical imaging system according to an exemplary embodiment of the present invention.
  • the medical imaging system 400 may comprise a resonant converter 200.
  • the medical imaging system 400 may be an X-ray imaging system or an X-ray radiography system or any other medical imaging system.
  • Figure 7 shows a schematic diagram of a flow-chart diagram of a method for producing a high voltage transformer.
  • the method comprising the steps of as follows:
  • a soft-magnetic core 30, a primary winding 10, and a secondary winding 20 may be performed.
  • an axial isolation-distance D2 spacing the secondary winding 20 from the soft-magnetic core 30 in an axial direction DA is larger than a first radial isolation-distance Dl spacing the secondary winding 20 from the soft-magnetic core 30 in a radial direction DR and/or larger than a second radial isolation-distance D3 spacing the secondary winding 20 from the primary winding 10 in the radial direction DR.
  • providing S3 an inductance for a resonant tank 150 coupled to the high voltage transformer 100 by adjusting a ratio of the axial isolation- distance D2 and the first radial isolation-distance Dl may be performed.
  • Figure 8 shows a schematic diagram of leakage inductances measured for different configurations of the secondary winding of the transformer according to an exemplary embodiment of the present invention.
  • the frequency is plotted in Hertz
  • the inductance in ⁇ is measured from the primary winding with short-circuited secondary winding.
  • Two cases, A and B, are compared, referring to two different models or for different configurations of the secondary winding of the high voltage transformer as described in the following.
  • the leakage inductance is clearly the largest for the B case (dashed line) for which of the 9 secondary winding slots available in the high voltage transformer 100 depicted in Fig. 5 two slots at the top and three slots at the bottom are left empty.
  • the leakage inductance may be smallest for the A case (solid line) for which of the 9 secondary winding slots available 8 slots may be filled with turns of the secondary winding and only the bottom slot is left empty.

Landscapes

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

Abstract

The present invention relates to a high voltage transformer (100) for resonant conversion, the high voltage transformer (100) comprising: a soft-magnetic core (30); a primary winding (10); and a secondary winding (20), which is arranged such that an axial isolation-distance (D2) spacing the secondary winding (20) from the soft-magnetic core (30) in an axial direction (DA) is larger than a first radial isolation-distance (D1) spacing the secondary winding (20) from the soft-magnetic core (30) in a radial direction (DR) or larger than a second radial isolation-distance (D3) spacing the secondary winding (20) from the primary winding (10) in the radial direction (DR); and wherein the secondary winding (20) is thereby configured to provide resonant tank inductance for a resonant tank (150) coupled to the high voltage transformer (100).

Description

Resonant converter
FIELD OF THE INVENTION
The present invention relates to a resonant converter comprising a high voltage transformer with compact secondary windings for resonant conversion and comprising a resonant tank.
The present invention also relates to a method for producing such a resonant converter.
BACKGROUND OF THE INVENTION
Resonant converters used as high voltage generators usually comprise both a high voltage transformer and an inductor in the resonant tank of the converter.
EP 2,560,175 Al describes a high-frequency transformer including a plurality of cores having a central leg, the cores being arranged to form core windows that are separated by the central legs. A primary winding has a predetermined length of electrically conductive wire that is wound about the central legs and extends through each of the core windows.
US 2013/328654 Al describes a coil device for a resonance transformer.
US 5 124 681 A describes a winding construction for a transformer.
US 2014/139313 Al describes a magnetic core and bobbin for a transformer.
US 2012/262895 Al describes a low-cost transformer assembly.
WO 87/05148 Al describes a high voltage transformer.
SUMMARY OF THE INVENTION
There may be a need to improve resonant converters. These needs are met by the subject-matter of the independent claims. Further exemplary embodiments are evident from the dependent claims and the following description.
An aspect of the present invention relates to a resonant converter comprising a high voltage transformer for resonant conversion and a resonant tank, the high voltage transformer comprising: a soft- magnetic core; a primary winding; and a secondary winding, which is arranged such that an axial isolation-distance spacing the secondary winding from the soft-magnetic core in an axial direction is larger than a first radial isolation-distance spacing the secondary winding from the soft-magnetic core in a radial direction or larger than a second radial isolation-distance spacing the secondary winding from the primary winding in the radial direction; and wherein the secondary winding is thereby configured to provide leakage inductance for the resonant tank coupled to the high voltage transformer.
In other words, the secondary winding is arranged such that an axial isolation- distance spacing the secondary winding from the soft-magnetic core in an axial direction is either larger than a first radial isolation-distance spacing the secondary winding from the soft-magnetic core in a radial direction or larger than a second radial isolation-distance spacing the secondary winding from the primary winding in the radial direction.
The term "high voltage" as used by the present invention may refer to a electrical voltage above a particular threshold, for instance above 1000 V or above 2500 V or above 5000 V or above 8000 V. High voltage may be used in electrical power distribution, in cathode ray tubes, to generate X-rays and particle beams, to demonstrate arcing, for ignition, lighting, in photomultiplier tubes, and in high power amplifier vacuum tubes and further applications.
The high voltage transformer according to the present invention may also be used for switched-mode power supplies, including resonant converters, further also for non- resonant hard- switching DC-DC converters with galvanic isolation, wherein the magnetizing inductance may be used as main inductor.
According to the present invention, when the transformer may be operated at sufficiently high frequencies, the leakage inductance of the transformer may be
advantageously used as the inductance of the resonant tank connected to the low voltage side of the transformer. The present invention may advantageously allow eliminating the resonant tank inductor which can be almost as bulky and heavy as the high voltage transformer.
Following common transformer design requirements, its dimensions will be determined by considerations regarding high voltage insulation and minimizing losses.
The present invention may advantageously provide an adjusting or controlling of the leakage inductance by varying the axial length of the secondary winding. The leakage inductance can be increased when the secondary winding is made more compact by reducing its axial length. This will result in the isolation- distance between secondary winding and primary winding or core being significantly larger on the top and bottom of the secondary winding than on its sides, for instance the radial sides.
The term "axial length" as used by the present invention may refer to the length of the secondary winding, i.e. its dimension parallel to the primary winding. The term "primary winding" as used by the present invention may refer to a coil forming the part of an electrical circuit such that changing current in it induces a current in a neighboring circuit. In other words, a current through the primary coil induces current in the secondary coil, thereby it may be defined what the term "secondary winding" as used by the present invention refers to.
The term "leakage inductance" as used by the present invention may refer to the electrical property of an imperfectly-coupled transformer whereby each winding behaves next to its function as a transformer winding also as a self-inductance constant in series with the winding's respective ohmic resistance constant.
According to a further, second aspect of the present invention, a method for producing a high voltage transformer is provided, the method comprising the steps of:
providing a soft-magnetic core, a primary winding, and a secondary winding; arranging the secondary winding in such a way that an axial isolation-distance spacing the secondary winding from the soft-magnetic core in an axial direction is larger than a first radial isolation- distance spacing the secondary winding from the soft-magnetic core in radial direction and providing an inductance for a resonant tank coupled to the high voltage transformer by adjusting a ratio of the axial isolation-distance and the first radial isolation-distance.
Advantageous embodiments of the present invention are represented in the dependent claims and discussed in the following.
According to an exemplary embodiment of the present invention, the axial isolation-distance is larger than 1.2 times or larger than 1.5 times or larger than 2.0 times or larger than 5.0 times the first radial isolation-distance. This advantageously allows precisely adjusting the leakage inductance provided.
According to an exemplary embodiment of the present invention, the secondary winding is arranged such that the axial isolation-distance spacing the secondary winding from the soft-magnetic core in the axial direction is larger than a second radial isolation-distance spacing the secondary winding from the primary winding in the radial direction, providing inductance for a resonant tank coupled to the high voltage transformer.
According to an exemplary embodiment of the present invention, the axial isolation-distance is larger than 1.2 times or larger than 1.5 times or larger than 2.0 times or larger than 5.0 times the second radial isolation-distance. This advantageously allows reducing the amount of external inductance needed.
According to an exemplary embodiment of the present invention, the high voltage transformer is configured to provide an output voltage of up to 5 kV or preferably of up to 25 kV or particularly preferred of up to 80 kV. This advantageously providing suffiently high output voltages.
For instance, this advantageously allows reaching a high voltage of 140kV after a four-stage cascade, if 35kV are provided as output voltage of the high voltage transformer.
According to an exemplary embodiment of the present invention, a secondary axial length of the secondary winding is smaller than 0.5 times a primary axial length of the primary winding.
According to an exemplary embodiment of the present invention, the high voltage transformer is configured to provide as the inductance for a resonant tank coupled to the high voltage transformer a leakage inductance of up to 2 μΗ or of up to 5 μΗ or of up to 10 μΗ.
According to a further aspect of the present invention, a resonant converter is provided comprising a resonant tank and a high voltage transformer according to the first aspect of the present invention or according to any implementation form of the first aspect.
According to an exemplary embodiment of the present invention, the resonant tank is configured to at least partially replace a resonance tank inductance by the provided inductance of the high voltage transformer. This advantageously allows reducing the number of electronic components or the space need for integration of the electronic components.
According to an exemplary embodiment of the present invention, the primary winding and/or the secondary winding are build in a slot winding or in a single layer winding or in a double layer winding or in any other kind of layer winding or in distributed layer winding.
According to a further aspect of the present invention, a medical system is provided comprising a resonant converter according to the previous aspect of the present invention or according to any implementation form of the previous aspect of the present invention.
A more complete appreciation of the present invention and the advantages thereof will be more clearly understood by reference to the following schematic drawings, which are not to scale, wherein:
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a schematic diagram of a resonant converter for explaining the present invention; Fig. 2 shows a schematic diagram of a high voltage transformer for explaining the present invention;
Fig. 3 shows a schematic diagram of a high voltage transformer for explaining the present invention;
Fig. 4 shows a schematic diagram of a high voltage transformer according to an exemplary embodiment of the present invention;
Fig. 5 shows a schematic diagram of a high voltage transformer according to an exemplary embodiment of the present invention;
Fig. 6 shows a schematic diagram of a medical imaging system according to an exemplary embodiment of the present invention;
Fig. 7 shows a schematic diagram of a flow-chart of a method for producing a high voltage transformer according to an exemplary embodiment of the present invention; and
Fig. 8 shows a schematic diagram of leakage inductances measured for different configurations of the secondary winding of the transformer according to an exemplary embodiment of the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS
The illustration in the drawings is purely schematic and does not intend to provide scaling relations or size information. In different drawings or figures, similar or identical elements are provided with the same reference numerals. Generally, identical parts, units, entities or steps are provided with the same reference symbols in the description.
Figure 1 shows a schematic diagram of a resonant converter used as high voltage generator according to an exemplary embodiment of the present invention.
The resonant converter 200 may comprise a resonant tank 150 and the high voltage transformer 100. The resonant tank 150 may comprise a resonant tank inductance 150-1 which may be at least partially replaced by the provided leakage inductance of the high voltage transformer 100.
The resonant converter 200 may further comprise an inverter circuit 210 and a voltage multiplier circuit 220.
According to an exemplary embodiment of the present invention, when the high voltage transformer 100 may be operated at high frequencies, then it may be of interest to use the leakage inductance of the high voltage transformer 100 as inductance or the tank inductance 150-1 in the resonant tank 150 connected to the low voltage side of the high voltage transformer 100. This may at least partially eliminate the resonant tank inductance 150-1 which can be almost as bulky and heavy as the high voltage transformer 100, if no further inductance is provided. The voltage multiplier 220 circuit may supply an X-ray tube 410.
Figure 2 shows a schematic diagram of a high voltage transformer for explaining the present invention. The secondary winding 20 of the high voltage transformer 100 may spread along its winding length, vertical axis in Figure 2.
As shown in Figure 2, the distance between the secondary winding 20, and the soft-magnetic core 30 of the high voltage transformer 100 and the primary winding 10 of the high voltage transformer 100 is almost constant. Such a design of the high voltage transformer 100 provides low losses and low leakage inductance.
Figure 3 shows a schematic diagram of a high voltage transformer with almost constant distance between the secondary winding 20 and the primary winding 10 or between the secondary winding 20 and the core 30.
According to an exemplary, not shown embodiment the secondary winding 20 as shown in Figure 3 may be modified as far as the number of winding turns per slot of the secondary winding 20 is concerned.
According to an exemplary embodiment of the present invention, the standard construction of a winding of the high voltage transformer 100 comprises a sequence of wide slots for taking up winding turns and narrow slots for returning the wire from the top of one neighboring wide slot to the bottom of the other neighboring wide slot. The sequence of wide slots and narrow slots is alternating coming from the outside.
According to an exemplary embodiment of the present invention, the wire enters a wide slot at its bottom, multiple turns are wound in the wide slot until it is filled; then the wire leaves the wide slot at its top, enters the adjacent narrow slot, is guided from the top of the narrow slot to the bottom of the narrow slot, and then leaves the narrow slot while entering the next wide slot and so on.
According to an exemplary embodiment of the present invention, this sequence may be repeated multiple times until at the end the wire leaves a wide slot at its top and then goes to the outside.
According to an exemplary embodiment of the present invention, the number of winding turns per winding slot of the secondary winding 20 of the high voltage transformer 100 may be varied from winding slot to winding slot, resulting in a non-equal distribution of the number of winding turns per winding slot of the secondary winding 20. According to an exemplary embodiment of the present invention, the number of winding turns per winding slot of the primary winding 10 may be varied from winding slot to winding slot, resulting in a non-equal distribution of the number of winding turns per winding slot of the primary winding 10.
Figure 4 shows a schematic diagram of a high voltage transformer according to an exemplary embodiment of the present invention. The secondary winding 20 of the high voltage transformer 100 is such arranged that an axial isolation-distance D2 spacing the secondary winding 20 from the soft-magnetic core 30 in an axial direction DA is larger than a first radial isolation-distance Dl spacing the secondary winding 20 from the soft-magnetic core 30 in a radial direction DR.
According to an exemplary embodiment of the present invention, the secondary winding 20 of the high voltage transformer 100 may be configured to provide a resonant tank inductance 150-1 for a resonant tank 150 coupled to the high voltage transformer 100.
According to an exemplary embodiment of the present invention, the secondary winding 20 of the high voltage transformer 100 may be arranged such that the axial isolation-distance D2 spacing the secondary winding 20 from the soft- magnetic core 30 in the axial direction DA is larger than a second radial isolation-distance D3 spacing the secondary winding 20 from the primary winding 10 in the radial direction DR, providing inductance for a resonant tank 150 coupled to the high voltage transformer 100.
In other words, a high voltage transformer 100 is provided, wherein the distance between the top and bottom of the high voltage transformer and the soft-magnetic core is significantly larger than the distance between its inside and the primary winding and the distance between its outside and the core.
In other words, the distance between the top and bottom of the secondary winding and the core will be considerably larger than the distance between its inside and the primary winding or the distance between its outside and the core. As a rough guideline, the axial isolation-distance D2 is larger than 1.2 times the first radial isolation-distance Dl .
According to an exemplary embodiment of the present invention, the leakage inductance can be adjusted by varying the axial length 20-1 of the secondary winding 20 of the high voltage transformer 100.
The soft- magnetic core 30 may be for instance a soft magnetic EC 123 ferrite core with a width of 123 mm, a height of 108 mm, and a depth of 30 mm. The soft- magnetic core 30 may have a round centre leg with 30 mm diameter and the cross section of the winding area is 34 mm wide and 82 mm high. The primary winding 10 of the high voltage transformer 100 may comprise 8 turns of two parallel 1700*0.071 Litz wires. The secondary winding 20 of the high voltage transformer 100 may comprise 120 turns of 250*0.071 Litz wire, resulting in a leakage inductance of 2.12 μΗ and a magnetizing inductance of 559 μΗ.
According to an exemplary embodiment of the present invention, the axial length of the secondary winding may be reduced by 10 % or by 20 % with respect to equally extended primary windings and secondary winding, resulting in an increase of the leakage inductance by 16%.
According to an exemplary embodiment of the present invention, the high voltage transformer 100 may be a closed-core transformer and may be constructed in 'core form' or 'shell form'. When windings surround the core, the transformer is core form; when windings are surrounded by the core, the transformer is shell form.
In Figure 4, both axial isolation-distances D2 of the high voltage transformer 100 spacing the secondary winding 20 from the soft-magnetic core 30, e.g. the top and the bottom axial isolation-distances D2, have the same length.
According to an exemplary embodiment of the present invention, however, it would be sufficient, if only one of these distances D2, e.g. either the top axial isolation- distance D2 spacing the secondary winding 20 from the soft-magnetic core 30 at the upper part or the bottom axial isolation-distance D2 spacing the secondary winding 20 from the soft-magnetic core 30 at the lower part of the high voltage transformer is larger than a first radial isolation-distance Dl spacing the secondary winding 20 from the soft-magnetic core 30 in a radial direction DR.
The same applies to the second radial isolation-distance D3. This means that either the top or the bottom axial isolation-distance D2 may be larger than the second radial isolation-distance D3.
In Figure 4, the number of winding turns per winding slot of the primary winding 10 and/or the secondary winding 20 may be varied from winding slot to winding slot of the primary winding 10 and/or the secondary winding 20, respectively.
According to an exemplary embodiment of the present invention , two different axial isolation-distances D2 at the upper part and the bottom part of the high voltage transformer spacing the secondary winding 20 from the soft- magnetic core 30 may be used.
Figure 5 shows a schematic diagram of a high voltage transformer according to an exemplary embodiment of the present invention. The high voltage transformer 100 may comprise a primary winding 10, a secondary winding 20, and a soft- magnetic core 30.
Figure 6 shows a schematic diagram of a medical imaging system according to an exemplary embodiment of the present invention.
According to an exemplary embodiment of the present invention, the medical imaging system 400 may comprise a resonant converter 200. The medical imaging system 400 may be an X-ray imaging system or an X-ray radiography system or any other medical imaging system.
Figure 7 shows a schematic diagram of a flow-chart diagram of a method for producing a high voltage transformer.
According to an exemplary embodiment of the present invention, the method comprising the steps of as follows:
As a first step of the method, providing SI a soft-magnetic core 30, a primary winding 10, and a secondary winding 20 may be performed.
As a second step of the method, arranging S2 the secondary winding 20 in such a way that an axial isolation-distance D2 spacing the secondary winding 20 from the soft-magnetic core 30 in an axial direction DA is larger than a first radial isolation-distance Dl spacing the secondary winding 20 from the soft-magnetic core 30 in a radial direction DR and/or larger than a second radial isolation-distance D3 spacing the secondary winding 20 from the primary winding 10 in the radial direction DR.
As a third step of the method, providing S3 an inductance for a resonant tank 150 coupled to the high voltage transformer 100 by adjusting a ratio of the axial isolation- distance D2 and the first radial isolation-distance Dl may be performed.
Figure 8 shows a schematic diagram of leakage inductances measured for different configurations of the secondary winding of the transformer according to an exemplary embodiment of the present invention.
On the X-axis, the frequency is plotted in Hertz, on the Y-axis the inductance in μΗ. The inductance of the secondary winding is measured from the primary winding with short-circuited secondary winding. Two cases, A and B, are compared, referring to two different models or for different configurations of the secondary winding of the high voltage transformer as described in the following.
According to an exemplary embodiment of the present invention, the leakage inductance is clearly the largest for the B case (dashed line) for which of the 9 secondary winding slots available in the high voltage transformer 100 depicted in Fig. 5 two slots at the top and three slots at the bottom are left empty.
According to an exemplary embodiment of the present invention, the leakage inductance may be smallest for the A case (solid line) for which of the 9 secondary winding slots available 8 slots may be filled with turns of the secondary winding and only the bottom slot is left empty.
It has to be noted that embodiments of the present invention are described with reference to different subject-matters. In particular, some embodiments are described with reference to method type claims whereas other embodiments are described with reference to device type claims.
However, a person skilled in the art will gather from the above and the foregoing description that, unless otherwise notified, in addition to any combination of features belonging to one type of the subject-matter also any combination between features relating to different subject-matters is considered to be disclosed with this application.
However, all features can be combined providing synergetic effects that are more than the simple summation of these features.
While the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the present invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art and practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.
In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or controller or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:
1. A resonant converter (200) comprising a high voltage transformer (100) for resonant conversion and a resonant tank (150), the high voltage transformer (100) comprising:
- a soft-magnetic core (30);
- a primary winding (10); and
- a secondary winding (20), which is arranged such that an axial isolation- distance (D2) spacing the secondary winding (20) from the soft- magnetic core (30) in an axial direction (DA) is larger than a first radial isolation-distance (Dl) spacing the secondary winding (20) from the soft-magnetic core (30) in a radial direction (DR) and/or larger than a second radial isolation-distance (D3) spacing the secondary winding (20) from the primary winding (10) in the radial direction (DR); and wherein the secondary winding (20) is thereby configured to provide leakage inductance for the resonant tank coupled to the high voltage transformer (100). 2. The resonant converter (200) according to claim 1,
wherein the axial isolation-distance (D2) is larger than 1.
2 times or larger than 1.5 times or larger than 2.0 times or larger than 5.0 times the first radial isolation-distance (Dl).
3. The resonant converter (200) according to claim 1 or 2,
wherein the axial isolation-distance (D2) is larger than 1.2 times or larger than 1.5 times or larger than 2.0 times or larger than 5.0 times the second radial isolation-distance (D3).
4. The resonant converter (200) according to one of the preceding claims 1 to 3, wherein the secondary winding (20) is arranged such that the axial isolation- distance (D2) spacing the secondary winding (20) from the soft- magnetic core (30) in the axial direction (DA) is larger than the first radial isolation-distance (Dl) and larger than the second radial isolation-distance (D3).
5. The resonant converter (200) according to one of the preceding claims 1 to 4, wherein the high voltage transformer (100) is configured to provide an output voltage of up to 5 kV, or preferably of up to 25 kV or particularly preferred of up to 80 kV.
6. The resonant converter (200) according to one of the preceding claims 1 to 5, wherein a secondary axial length (20-1) of the secondary winding (20) is smaller than 0.5 times a primary axial length (10-1) of the primary winding (10).
7. The resonant converter (200) according to one of the preceding claims 1 to 6, wherein the high voltage transformer (100) is configured to provide as the inductance for a resonant tank (150) coupled to the high voltage transformer a leakage inductance of up to 2 uH or of up to 5 uH or of up to 10 uH.
8. The resonant converter (200) according to one of the preceding claims 1 to 7, wherein the primary winding (10) and/or the secondary winding (20) are build in a slot winding or in a single layer winding or in a double layer winding or in any other kind of layer winding or in distributed layer winding.
9. The resonant converter (200) according to claim 8,
wherein the resonant tank (150) is configured to at least partially replace a resonant tank inductance (150-1) by the provided inductance of the high voltage transformer (100).
10. A medical imaging system (400) comprising a resonant converter (200) according to one of the preceding claims 1 to 9.
1 1. A method for producing a resonant converter (200) comprising a high voltage transformer and a resonant tank, the method comprising the steps of:
- providing (SI) a soft- magnetic core (30), a primary winding (10), and a secondary winding (20);
- arranging (S2) the secondary winding (20) in such a way that an axial isolation-distance (D2) spacing the secondary winding (20) from the soft-magnetic core (30) in an axial direction (DA) is larger than a first radial isolation-distance (Dl) spacing the secondary winding (20) from the soft-magnetic core (30) in an radial direction (DR) and/or larger than a second radial isolation-distance (D3) spacing the secondary winding (20) from the primary winding (10) in the radial direction (DR); and
- providing (S3) a leakage inductance for the resonant tank coupled to the high voltage transformer by adjusting a ratio of the axial isolation-distance (D2) and the first radial isolation-distance (Dl).
12. The method according to claim 1 1,
wherein the axial isolation-distance (D2) is larger than 1.2 times or lager than 1.5 times or larger than 2.0 times or larger than 5.0 times the first radial isolation-distance (Dl).
13. The method according to claim 1 1 or claim 12, wherein
- the step of arranging (S2) the secondary winding (20) comprises both arranging the secondary winding (20) such that the axial isolation-distance (D2) spacing the secondary winding (20) from the soft-magnetic core (30) in the axial direction (DA) is larger than the second radial isolation-distance (D3) spacing the secondary winding (20) from the primary winding (10) in the radial direction (DR) and that the axial isolation-distance (D2) spacing the secondary winding (20) from the soft- magnetic core (30) in an axial direction (DA) is larger than the first radial isolation-distance (Dl) spacing the secondary winding (20) from the soft-magnetic core (30) in the radial direction (DR); and
- the step of providing (S3) the inductance for the resonant tank coupled to the high voltage transformer comprises adjusting a ratio of the axial isolation-distance (D2) and the second radial isolation-distance (D3).
14. The method according to claim 13,
wherein the axial isolation-distance (D2) is larger than 1.2 times or lager than 1.5 times or larger than 2.0 times or larger than 5.0 times the second radial isolation-distance (D3).
PCT/EP2015/074587 2014-11-03 2015-10-23 Resonant converter WO2016071123A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP14191428 2014-11-03
EP14191428.3 2014-11-03

Publications (1)

Publication Number Publication Date
WO2016071123A1 true WO2016071123A1 (en) 2016-05-12

Family

ID=51846513

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2015/074587 WO2016071123A1 (en) 2014-11-03 2015-10-23 Resonant converter

Country Status (1)

Country Link
WO (1) WO2016071123A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106298176A (en) * 2016-08-30 2017-01-04 苏州泰思特电子科技有限公司 High frequency voltage bonder based on mixing magnetic core principle

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1987005148A1 (en) * 1986-02-21 1987-08-27 Thomson-Cgr High voltage transformer
US5124681A (en) * 1991-04-26 1992-06-23 Delta Electronics, Inc. Winding construction for a transformer
US5608771A (en) * 1995-10-23 1997-03-04 General Electric Company Contactless power transfer system for a rotational load
US5886516A (en) * 1997-05-30 1999-03-23 Delco Electronics Corp. Series resonant converter transformer assembly having integral inductor tank elements
US20100019874A1 (en) * 2008-07-25 2010-01-28 Melanson John L Transformer With Split Primary Winding
US20120140525A1 (en) * 2010-12-01 2012-06-07 Power Integrations, Inc. Energy transfer assembly with tuned leakage inductance and common mode noise compensation
US20120262895A1 (en) * 2011-04-15 2012-10-18 Power Integrations, Inc. Low-cost transformer assembly
US20130049913A1 (en) * 2011-07-06 2013-02-28 Tdk Korea Corporation Coil device
US20130328654A1 (en) * 2012-06-08 2013-12-12 Tdk Corporation Coil device
US20140139313A1 (en) * 2012-11-21 2014-05-22 Delta Electronics, Inc. Magnetic core and bobbin and transformer using the same

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1987005148A1 (en) * 1986-02-21 1987-08-27 Thomson-Cgr High voltage transformer
US5124681A (en) * 1991-04-26 1992-06-23 Delta Electronics, Inc. Winding construction for a transformer
US5608771A (en) * 1995-10-23 1997-03-04 General Electric Company Contactless power transfer system for a rotational load
US5886516A (en) * 1997-05-30 1999-03-23 Delco Electronics Corp. Series resonant converter transformer assembly having integral inductor tank elements
US20100019874A1 (en) * 2008-07-25 2010-01-28 Melanson John L Transformer With Split Primary Winding
US20120140525A1 (en) * 2010-12-01 2012-06-07 Power Integrations, Inc. Energy transfer assembly with tuned leakage inductance and common mode noise compensation
US20120262895A1 (en) * 2011-04-15 2012-10-18 Power Integrations, Inc. Low-cost transformer assembly
US20130049913A1 (en) * 2011-07-06 2013-02-28 Tdk Korea Corporation Coil device
US20130328654A1 (en) * 2012-06-08 2013-12-12 Tdk Corporation Coil device
US20140139313A1 (en) * 2012-11-21 2014-05-22 Delta Electronics, Inc. Magnetic core and bobbin and transformer using the same

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
LU B ET AL: "Optimal Design Methodlogy for LLC Resonant Converter", APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, 2006. APEC '06. T WENTY-FIRST ANNUAL IEEE MARCH 19, 2006, PISCATAWAY, NJ, USA,IEEE, PISCATAWAY, NJ, USA, 19 March 2006 (2006-03-19), pages 533 - 538, XP010909996, ISBN: 978-0-7803-9547-3, DOI: 10.1109/APEC.2006.1620590 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106298176A (en) * 2016-08-30 2017-01-04 苏州泰思特电子科技有限公司 High frequency voltage bonder based on mixing magnetic core principle

Similar Documents

Publication Publication Date Title
WO2020248672A1 (en) Planar transformer, power conversion circuit, and adapter
US7567162B2 (en) Apparatus and method for winding an energy transfer element core
RU2374713C2 (en) Planar high-voltage transformer
US10978241B2 (en) Transformers having screen layers to reduce common mode noise
CN104183374A (en) Isolation transformer for use in isolated dc-to-dc switching power supply
JP2010136618A (en) Transformer with high-voltage isolation function
US20150228393A1 (en) High-Voltage Transformer Apparatus with Adjustable Leakage
EP2409309B1 (en) High voltage transformer
TWM459503U (en) High-voltage transfomer structure
US20230335333A1 (en) Coil and a Transformer That Have Improved Electromagnetic Shielding
WO2016071123A1 (en) Resonant converter
CN109643605B (en) Inductor for high frequency and high power applications
CN110391073A (en) Circuit device, X-ray apparatus and computed tomographic scanner
CN111326330A (en) Coil assembly, pulse transformer and medical equipment
CN111029133B (en) Winding method of high-frequency high-power low-leakage-inductance transformer
JP2016119753A (en) Power conversion device
CN219066578U (en) Magnetic element and power electronic transformer
US6934165B2 (en) Loosely coupled parallel resonant converter
KR102561384B1 (en) Electrical components, especially transformers or inductors
US11031819B2 (en) System for wireless power transfer between low and high electrical potential, and a high voltage circuit breaker
JP2016119752A (en) Power conversion device
TW201523655A (en) Transformer and power supply circuit using same
CN108987222A (en) A kind of circuit structure of LC resonance X-ray tube filament heating
CN114746965A (en) Intermediate frequency transformer with parallel windings

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 15784388

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 15784388

Country of ref document: EP

Kind code of ref document: A1