Patent Grant
10424434
This application is a 35 U.S.C. § 371 National Stage Application of PCT/EP2012/073650, filed on Nov. 26, 2012, the disclosure of which is incorporated herein by reference in its entirety.
The invention relates to a winding arrangement for inductive components and a method for manufacturing a winding arrangement for inductive components.
Although applicable to any inductor component, the present invention will be described in combination with inductive components with a high fill factor.
In modern electric and electronic devices winding arrangements for inductive components are an important component. Inductors are especially used in power conversion devices like buck converters and boost converters.
In order to reduce the size of such power conversion devices the working frequencies of said devices become higher. For small power converters up to 10V the working frequencies have risen into the MHz range. For middle sized power converters up to 200V and high power converters up to 500V the target frequency is about 300 kHz to 1 MHz.
In such power conversion devices the inductive components (inductors or transformers) are an important factor regarding losses and size. Particularly, the size of the inductive components should be as small as possible, the shape should be square and the AC/DC resistance ratio should be as low as possible at the desired working frequency.
Common inductive elements—like shown in
With the constant increase of the working frequency of such power conversion devices the so called “skin effect” becomes more and more relevant when designing power conversion devices. The skin effect is responsible for the current being conducted in a skin area of the conductor, wherein the skin depth δ becomes smaller with higher frequencies. The skin depth δ is about 0.1 mm or less for frequencies in the MHz area. Therefore, the thickness of the conductors of such common inductive elements like the one shown in
Inductors can also comprise flat band conductors instead of litz wires. Such inductors are shown in
A certain percentage of flux lines inevitably passes the winding windows 2a″″ and 2b″″, which effects that not all of the winding turns N1, N2 include the same flux causing differences in induced voltage in individual turns. Specifically, as seen in
In the case of all the winding turns N1, N2 being connected in series, as it is commonly used for the windings of inductive components, the difference in the induced voltage of the winding turns in different positions in the winding windows 2a″″ and 2b″″ has no negative effect, because the induced voltages of all winding turns N1, N2 are summed up and therefore cause no equalizing currents.
In order to reduce the ohmic losses caused due to high frequency current, the demand for thinning the conductor thickness increases drastically. The thickness thinning of the conductors with round intersection results in increase of the number of litzes in the strand in order to be able to conduct the load current. The thinner the litz wires are the worse the fill-factor of such winding is. Thinning the square intersection flat conductors limits the maximum possible load current. The load current can be increased by the expansion of the winding window, which is possible only to certain limits set due to the outside inductor dimension ratio. Division of the individual flat conductor strips into more strips is not possible, since interleaving, which is normally used in litz strand conductors cannot be achieved.
However, the flat wires do achieve a much better fill factor than litz wires, since they present an advantage in the possibility of compensating the thinning of the conductors by increasing the width of individual conductors. The simultaneous increase of the length of the winding windows 2a″″ and 2b″″ is possible only within certain limits, therefore in such multi-layer windings single flat band conductors connected in parallel to form a single winding presents a possible solution.
Despite the equalizing currents in litz or strand wires being negligible the fill factor deteriorates the high frequency operation for high currents applications, since with the frequency increase the isolator/conductor ratio raises.
Besides the voltage change occurring due to the different position of the winding turns N1, N2 in the winding windows 2a″″ and 2b″″ there are also other aspects that deteriorate the high frequency operation for high current applications. The load current of individual winding turns N1, N2 influences the current in all of the other turns of the same winding by creating its own magnetic field causing longitudinal circular current flowing on the inner and outer side of the individual conductor with respect to the core. These longitudinal circular currents are summed up with the load current, such that the load current is increased on the inner side of the conductor and decreased on the outer side of the conductor, this phenomena is called proximity effect. The consequence of the proximity effect are greater ohmic losses with the increase of frequency.
Using flat band conductors in parallel solves the skin and proximity effect, while simultaneously allowing the same load current to flow through the winding as the effective conductive area remains the same. Specifically,
Dividing individual conductors into flat band strips solves the fill factor, skin effect and proximity effect issue at the same time. The flux leakage into the area of the winding windows 2a″″ and 2b″″ cannot be removed. The flux tends to flow through low permeability areas such as isolator or air in the winding window area and partly through the conductors. The gap GW″ between both parallel conductor strips S1″ and S2″ presents an area for the flux lines ΦW to penetrate into it resulting in a voltage difference ΔV among individual parallel conductor strips S1″ and S2″ of the same conductor.
Therefore, an additional voltage causing longitudinal current IWL through parallel conductor strips S1″ and S2″ and both connection taps T1″″, T2″″ appears, as demonstrated in
Document WO 2007/136288A1 shows a method for winding a high-frequency transformer by winding a strip of electrically conductive material around a core in two parallel windings.
This problem is solved by the features of the independent claims.
Accordingly, the present patent application provides:
The present invention is based on the idea that the longitudinal current through parallel conductor strips should be eliminated to improve the efficiency of an inductor.
Therefore, the present invention provides a winding arrangement for inductive components where the winding of the inductor is divided into two separate winding sections. Furthermore, the single winding section each comprises at least one winding, which is formed of a flat band stack of flat band conductors.
In order to effectively remove the longitudinal current through parallel conductor strips the connection between the first flat band stack of the first winding section and the second flat band stack of the second winding section is arranged as a cross connection. Furthermore, the first flat band stack forms a first winding which is wound in a first direction and the second flat band stack forms a second winding, which is wound in a second direction which is opposite to the first direction.
Concerning the present patent application “cross connection” means that the flat band conductors of the first winding section are connected to the flat band conductors of the second winding section in reversed order. That means the first flat band conductor of the first winding section is connected to the last flat band conductor of the second winding section, the second flat band conductor of the first winding section is connected to the second to last flat band conductor of the second winding section, and so forth. Therefore a first current flow stacking sequence in the first flat band stack is reversed compared to a second current flow stacking sequence in the second flat band stack.
Finally, the ends of the flat band conductors which exit the first winding section and the second winding section, respectively, are electrically connected together in each case to form electrical taps, which are used to electrically interface the inductor.
The cross connection according to the present invention greatly reduces longitudinal currents in parallel flat band conductors. Thus, the flat conductor strips can be used and the effective intersection area of the winding window is increased and the DC/AC resistance ratio is reduced. The parallel arrangement of the flat band strips in each individual winding allows the intersection to be adapted to different winding window shapes. Furthermore, the parallel arrangement of the flat band conductors allows narrowing of the strips and, therefore, lowers the parasitic capacitance of the windings.
Finally, the ohmic losses are reduced in an inductor according to the present invention. Consequently, further frequency increases with simultaneous reductions in size become possible.
Further embodiments of the present invention are subject of the dependent claims and of the following description, referring to the drawings.
In one embodiment the at least one first winding is wound in a first winding direction with regard to a virtual axis of the winding arrangement for inductive components and the at least one second winding is wound in a second winding direction being opposite to the first winding direction with regard to the virtual axis of the winding arrangement for inductive components.
In a preferred embodiment of the winding arrangement for inductive components at least one first winding is wound on a first magnetic core and at least one second winding is wound around a second magnetic core.
In a preferred embodiment the stacking sequence is reversed through the at least one first winding and the at least one second winding being wound around the first magnetic core and the second magnetic core, respectively, in an s-shaped arrangement. This allows providing a reverse current flow stacking sequence in the first winding section compared to the second winding section without, the need to explicitly provide a cross section, because the cross section is implicitly formed by the s-shaped arrangement.
In a preferred embodiment the winding arrangement for inductive components comprises a magnetic core, the first winding section including the at least one first winding being wound around the core in the first winding direction and the second winding section including the at least one second winding being wound around the core in the second winding direction connected between each other with the cross-connection. Using a magnetic core further improves the inductivity of the winding arrangement for inductive components according to the present invention.
In a preferred embodiment the first winding section and the second winding section are configured essentially symmetrical. If the first winding section and the second winding section are configured essentially symmetrical the longitudinal currents in parallel flat band conductors are optimally reduced.
In the context of the present patent application the term “symmetrical” does not necessarily refer to a mechanical or geometrical symmetry. Rather, the term symmetrical can also refer to electrically symmetry. This means that in both winding sections the same electrical voltage is induced or that both winding sections circumvent the same amount of magnetic flux between the individual parallel conductive flat bands.
In a preferred embodiment the first winding section comprises at least two first windings, the electrical conductors of the at least two first windings being connected electrically in series in a direct connection and the at least two first windings being wound in alternating directions.
In a preferred embodiment the second winding section comprises at least two second windings, the electrical conductors of the at least two second windings being connected electrically in series in a direct connection and the at least two second windings being wound in alternating directions.
Providing the first winding section and the second winding section with a plurality of windings allows further reducing the capacitance of the winding sections.
In a preferred embodiment the cross connection is arranged at the innermost loop of the at least one first winding and the at least one second winding. This allows integrating the cross connection into the inductor and building a very compact inductor.
In a preferred embodiment the cross connection is arranged at the outermost loop of the at least one first winding and the at least one second winding. On the outer region of the windings there is more space available for the cross connection. Therefore, easy construction and assembly of the winding arrangement for inductive components becomes possible.
In a preferred embodiment the cross connection is implemented by an electric wiring arrangement. This allows providing a very simple cross connection.
In a preferred embodiment the cross connection is implemented by a folding arrangement of the at least one first winding section and/or the at least one second winding section. This allows providing a very compact cross connection which can be embedded deeply in the winding arrangement for inductive components without the need to establish the cross connection using e.g. soldering tools.
In a preferred embodiment the first winding section and the second winding section with the cross connection in between are implemented by a folding arrangement of one single longitudinal flat band stack. This allows providing a very simple and, therefore, cost effective arrangement for the windings of the winding arrangement for inductive components.
In a preferred embodiment the first winding section and the second winding section with the cross connection in between are implemented by a folding arrangement of one u-shaped flat band stack, the first winding section being formed by a first arm of the u-shaped flat band stack, the second winding section being formed by a second arm of the u-shaped flat band stack, and the cross section being formed by a connection element of the u-shaped flat band stack, which connection element connects the first arm and the second arm of the u-shaped flat band stack. This allows providing a very compact cross connection.
For a more complete understanding of the present invention and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings. The invention is explained in more detail below using exemplary embodiments which are specified in the schematic figures of the drawings, in which:
a,b,c,d are perspective views of the flat band stack of the eighth embodiment shown in
a,b,c are perspective views of the flat band stack of the ninth embodiment of the winding arrangement for inductive components shown in
a,b,c are perspective views of the flat band stack of the eleventh embodiment of the winding arrangement for inductive components shown in
The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate the embodiments of the present invention and together with the description serve to explain the principles of the invention. Other embodiments of the present invention and many of the intended advantages of the present invention will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily drawn to scale relative to each other. Like reference numerals designate corresponding similar parts.
The winding arrangement for inductive components I1 of
The first winding WA1 comprises two flat band conductors S1, S2 being configured as a first flat band stack ST.
The second winding WB1 also comprises two flat band conductors S1′, S2′ being configured as a second flat band stack ST′.
Finally first ends of the flat band conductors S1, S2 and S1′, S2′ are cross connected in a cross connection CC, CC1-CC2 such that a first current flow stacking sequence in the first flat band stack ST is reversed to a second current flow stacking sequence in the second flat band stack ST′. Precisely, flat band conductor S1 is connected to flat band conductor S2′ and flat band conductor S2 is connected to flat band conductor S1′.
The winding arrangement for inductive components I2 comprises a first winding section WA and a second winding section WB. The first winding section WA comprises a plurality of first windings WA1-WAn, wherein only three of the first windings WA1, WA2 and WAn are displayed. The second winding section WB comprises a plurality of second windings WB1-WBn, wherein only three of the second windings WB1, WB2 and WBn are displayed. The first windings WA1-WAn, and the second windings WB1-WBn, respectively, are connected in series with a direct connection CD in each case. The position of the direct connection CD alternates between
Between the first winding section WA and the second winding section WB the innermost windings WA1 and WB1 are cross connected in a cross connection CC.
Finally, the ends of the flat band connectors S1-S4 of the first winding section WA are electrically connected together in a first tap T1 and the ends of the flat band connectors S1′-S4′ of the second winding section WB are electrically connected together in a first tap T2.
In
In
The winding arrangement for inductive components I3 of
In
In
The first winding direction DCC in
In
The first winding WA2 and the second windings WB1 and WBn are wound in the second winding direction DCW.
In one embodiment the number of the individual windings within one winding section is the same for both winding sections WA and WB.
Finally, the ends of the flat band connectors S1-S2 of the first winding WAn are electrically connected together in a first tap T1 and the ends of the flat band connectors S1′-S4′ of the second winding WBn are electrically connected together in a first tap T2.
The windings in
In the middle, between the first winding section WA and the second winding section WB the single flat band conductors S1-S5 of the first winding section WA and the single flat band conductors S1′-S5′ of the second winding section WB are connected to each other in a cross connection CC.
In
The first flat band conductors S1-S5 of the first winding section WA are connected to the second flat band conductors S1′-S5′ of the second winding section WB in the manner to change the current flow stacking sequence, such that the first flat band conductor S1 of the first winding section WA is connected to the second flat band conductor S5′ of the second winding section WB, the first flat band conductor S2 of the first winding section WA is connected to the second flat band conductor S4′ of the second winding section WB, and so on. The number of the insulated flat conductor strips is the same for both winding sections WA and WB.
One direct connection CD1-CD5 is provided for every one of the first flat band conductors S1-S5. The first flat band conductors S1-S5 of the first winding WA1 are connected to the first flat band conductors S1-S5 of the first winding WA2 in the manner to keep the current flow stacking sequence unchanged, such that the first flat band conductor S1 of the first winding WA1 is connected to the first flat band conductors S1 of the first winding WA2, that the first flat band conductor S2 of the first winding WA1 is connected to the first flat band conductors S2 of the first winding WA2, and so on. The number of flat band conductors S1-S5 is the same for both symmetrical windings. In the embodiment of
The vertical cross section of a preferred embodiment of the winding arrangement for inductive components I6 according to the present invention shows a magnetic core 1′ with winding windows 2a′ and 2b′. In the winding windows 2a′ and 2b′ are arranged a first winding section WA′ and a second winding section WB′, the first winding section WA′ comprising a first winding WA1′ and the second winding section WB′ comprising a second winding WB1′. Each one, the first winding WA1 and the second winding WB1 comprises two flat band conductors S1, S2 and S1′, S2′ and has five turns.
The position of the cross connection CC1, CC2 of the first winding WA1 of the first winding section WA with the second winding WB1 of the second winding section WB is at the innermost turn of the first winding WA1 and the second winding WB1. A magnified version of the cross connection is shown in an enlargement A1.
A cross connection CC1 connects the flat band conductor S1 of the first winding WA1 of the first winding section WA′ to the flat band conductors S2′ of the second winding WB1 of the second winding section WB′. Furthermore, a cross connection CC2 connects the flat band conductor S2 of the first winding WA1 of the first winding section WA′ to the flat band conductors S1′ of the second winding WB1 of the second winding section WB′. The cross sections are shown in detail in enlargement A1.
For the first winding WA1 and the second winding WB1 a tap T1 and a Tap T2, respectively, are arranged on the outer side of the respective winding WA1, WB1 to form convenient contacts of the winding arrangement for inductive components I6.
The vertical cross section of a preferred embodiment of the winding arrangement for inductive components I7 according to the present invention shows a magnetic core 1″ with winding windows 2a″ and 2b″. In the winding windows 2a″ and 2b″ are arranged a first winding section WA″ and a second winding section WB″.
The vertical cross section of a preferred embodiment of the winding arrangement for inductive components I7 according to the present invention differs from the winding arrangement for inductive components I6 of
Between the first winding WA1 and the first winding WA2 a direct connection CD1 connects the flat band conductor S1 of the winding WA1 to the flat band conductor S1 of the winding WA2. Furthermore, a direct connection CD2 connects the flat band conductor S2 of the winding WA1 to the flat band conductor S2 of the winding WA2. The direct connection is shown in detail in enlargement B1.
Analogous direct connections CD1 and CD2 are established between the flat band conductor S1′ of the winding WB1 to the flat band conductor S1′ of the winding WB2 and the flat band conductor S2′ of the winding WB1 and the flat band conductor S2′ of the winding WB2.
A cross connection CC1 connects the flat band conductor S1 of the first winding WA1 of the first winding section WA′ to the flat band conductors S2′ of the second winding WB1 of the second winding section WB′. Furthermore, a cross connection CC2 connects the flat band conductor S2 of the first winding WA1 of the first winding section WA′ to the flat band conductors S1′ of the second winding WB1 of the second winding section WB′. The cross sections are shown in detail in enlargement A2.
For the first winding WA2 and the second winding WB2 a tap T1″ and a Tap T2″, respectively, are arranged on the outer side of the respective winding WA2, WB2 to form convenient contacts of the winding arrangement for inductive components I7.
The flat band stack ST, ST′ extends longitudinally such that the length of the flat band stack ST, ST′ is larger than the width of the flat band stack ST, ST′.
In
a,b,c are perspective views of the flat band stack ST, ST′ of the eighth embodiment shown in
The sequence of the
The flat band stack ST, ST′ is bent in the same direction on the folding lines BL1 and BL2. The folding along folding lines BL1 and BL2 of
The first two foldings in
First winding WA1 is wound counterclockwise in the first winding direction DCC as shown in
In all
The flat band stack ST, ST′ in
In
a,b,c are perspective views of the flat band stack ST, ST′ of the ninth embodiment of the winding arrangement for inductive components I9 shown in
The sequence of the figures demonstrates the sequence of the folding procedure.
The u-shaped flat band stack ST, ST′ of
The bending that is demonstrated in
The first winding WA1 is wound in the first winding direction DCC counterclockwise as shown in
In
In
The flat band stack ST in
The upper arm will form the first winding WA1 and the lower arm will form the first winding WA2.
a,b are perspective views of the flat band stack ST, ST′ of the tenth embodiment I10 shown in
The preferred embodiment of the first windings WA1 and WA2 according to
The first and second windings WA1 and WA2 of
Furthermore, the flat band which forms the first and second windings WA1 and WA2 comprises two folding lines BL1′ and BL2′, where the first folding line BL1′ extends from the center top of the flat band in a 45° angle down to the left and where the second folding line BL2′ extends from the center bottom of the flat band in a 45° angle up to the right. Between the first folding line BL1′ and the second folding line BL2′ a distance 6 can be arranged in one embodiment.
The second preferred embodiment of the winding procedure having a direct connection CD between individual windings WA1 and WA2 wound out of the straight isolated flat band is demonstrated in
The direct connection CD is performed by two bendings along the folding lines BL1 and BL2 shown in
The
The winding arrangement for inductive components I12 of
The winding arrangement for inductive components I12 comprises a first winding WA′″ which is formed of six flat band conductors S1-S6 which are wound around the first magnetic core 1a′″ and passed in between the two magnetic cores 1a′″ and 1b′″ to be wound around the second magnetic core 1b′″, forming a second winding WB′″. The ends of the six flat band conductors S1-S6 are electrically connected together to form a first tap T1 on one end and a second tap T2 on the other end.
In
In and the undesired stressed flux Φ″={Φ1″ . . . Φn″}; nϵ
.
Each turn N1, N2 starting from the inside to the outside includes more flux lines, such that the turn N1 includes Φ1 flux lines, which consists of the core flux Φ′ and Φ1″ and the turn N2 includes Φ2 flux lines consisting of the core flux Φ′ plus Φ1″ and Φ2″.
In
The winding gap flux Φg as a part of stressed flux Φ″ of
In
The winding gap flux Φg is causing the longitudinal equalizing current IWL along the whole length of the stretched conductor, which represents the winding W of the inductive component.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations exist. It should be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents. Generally, this application is intended to cover any adaptations or variations of the specific embodiments discussed herein.
In the foregoing detailed description, various features are grouped together in one or more examples or examples for the purpose of streamlining the disclosure. It is understood that the above description is intended to be illustrative, and not restrictive. It is intended to cover all alternatives, modifications and equivalents as may be included within the scope of the invention. Many other examples will be apparent to one skilled in the art upon reviewing the above specification.
Specific nomenclature used in the foregoing specification is used to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art in light of the specification provided herein that the specific details are not required in order to practice the invention. Thus, the foregoing descriptions of specific embodiments of the present invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed; obviously many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. Throughout the specification, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein,” respectively. Moreover, the terms “first,” “second,” and “third,” etc., are used merely as labels, and are not intended to impose numerical requirements on or to establish a certain ranking of importance of their objects.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2012/073650 | 11/26/2012 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2014/079516 | 5/30/2014 | WO | A |
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| 20080196239 | Wang | Aug 2008 | A1 |
| 20080231408 | Wang | Sep 2008 | A1 |
| 20110279208 | Ono | Nov 2011 | A1 |
| Number | Date | Country |
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| 100 40 415 | Jan 2002 | DE |
| 10040415 | Jan 2002 | DE |
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| 2 251 959 | Nov 2010 | EP |
| 2 609 205 | Jul 1988 | FR |
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| Entry |
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| International Search Report corresponding to PCT Application No. PCT/EP2012/073650, dated Oct. 7, 2013 (3 pages). |
| Number | Date | Country | |
|---|---|---|---|
| 20150325361 A1 | Nov 2015 | US |
