DE202010018206U1 - throttle - Google Patents

Abstract

Choke (1) with a choke core (2) and a choke winding (3) which is wound around the choke core (2), characterized in that the choke winding (3) in a first winding (4) and a second winding (5) is divided, the first winding (4) being designed as a strand-shaped winding (5) in which the individual strand wires (6) are individually electrically insulated, and the second winding (5) being designed as a solid winding.

Description

The invention relates to a throttle with a throttle core and a throttle winding.

Chokes are known for example inverters, consisting of a core and a winding with a round conductor. Usually, the throttle is such that the core is surrounded by the winding in the case of an E-shaped core, while in the case of a U-shaped core the two outer limbs comprise the winding.

Such chokes take a relatively large space in an inverter, since these chokes are used, for example, as filter chokes on a network side of the inverter or as boost chokes, which is due to the relatively high current that must be considered for such circuits, a large cross-section of the Winding conductor results. If the conductor cross-section of the windings is reduced, not only does the ohmic losses increase, but there is a risk that the temperature of the winding will become so high that the insulation of the winding melts and thus irreversible damage to the component occurs. A correspondingly voluminous core, which conducts the magnetic field, must also be taken into account in order to limit magnetic losses. Magnetic losses result in further heating of the component leading to additional temperature rise inside an inverter housing or inside another housing for, for example, a general switching power supply, a power factor control (PFC) stage, or other electrical circuitry or components leads.

The invention has for its object to provide a choke with high efficiency with consequently low losses, which has a lower heating and is low-loss and also has a small and lightweight design.

This object is achieved by a throttle with the characterizing features of claim 1 in conjunction with its preamble features.

The invention is based on the finding that in circuits for inverters, switching power supplies, PFC stages or other circuits in the inductor both a DC component and a high-frequency current component is present. Due to the so-called skin effect on the one hand and by magnetic influence or the so-called proximity effect on the other hand, the current is not uniformly distributed in the cross section of the winding conductor, so that in certain areas a high current density and in other areas a lower current density occurs. Due to the high current density occur relatively high losses with a correspondingly high heating.

Due to the skin effect, the high-frequency current essentially flows in a circular conductor in the outer region of the conductor cross-section.

Another current displacement effect or the proximity effect occurs by influencing adjacent turns of the throttle. The current of one turn ensures that the current of another turn flows unevenly.

Although such effects are known in specific fields, in throttling technology no practical solutions could be found to reduce losses.

For example, such effects can be illustrated by busbars in a low-voltage distributor. This is illustrated by the DE 38 19 575 A1 in that current flows around the busbar so that magnetic fields build up which lead to a higher current density at the mutually opposite edge regions of the busbars. Therefore, there the wall thicknesses of a C-shaped profile cross-section are so uneven that those walls that are closest to each other with busbars mounted next to each other, have a greater thickness than the lying parallel to a connection plane walls. As can be seen from this document, the bus bars are C-shaped, so that they are comparable to a waveguide, which should be optimal for a consideration of the skin effect. Such busbar currents have only an alternating current component of 50 Hz, but no high-frequency current component and no direct current component.

In order to optimally take into account both current displacement effects for high-frequency currents and also to allow a high DC component, there is a division into two windings. Both windings are almost electrically connected in parallel.

The invention is based on the idea that the reactor winding is split, in a winding for the alternating current, d. H. in, for example, an HF winding with HF strands and a preferably arranged above winding of, for example, a rectangular wire, which sits in particular edgewise on the RF strands. An HF strand consists of individual wires, in particular copper wires, which are individually insulated and twisted together.

The cross section of the HF winding and the massive winding depends on the current density present in the conductors. By the invention is given a substantially uniform current density in the RF winding. Due to the individual conductors in the HF strand, the high-frequency current can be distributed relatively uniformly in the HF strand, since the insulation of the many individual conductors prevents current displacement. The current is, so to speak, "trapped in the individual conductors or in the surface".

For the DC is essentially the massive conductor, d. H. the rectangular wire provided. Conveniently, this has a larger conductor cross-section than the strand. Since the massive conductor because of the DC d. H. DC component no skin effect occurs, is present in the core of the conductor as high current density as in the edge regions of the head. A uniform current distribution in both windings is so important because the power dissipation increases with the square of the current, as illustrated below.

It is advantageous if the current densities of the HF strand and of the copper or solid conductor are in the same ratio to one another.

The power loss Pv (active power) is, in simple terms, represented by the following equation: Pv = U × I (1)

U

= Gleichspannung an dem Spulenleiter,

I

= Strom

Here are:

U

= DC voltage on the coil conductor,

I

= Electricity

By Ohm's law the tension can be replaced by: U = R × I (2)

Here, R is the ohmic resistance of the conductor.

Substituting equation (2) into equation (1) results in: Pv = R × I ² (3)

By the invention, both a reduction of the throttle losses and a significant reduction of the throttle design is possible.

Further advantageous embodiments of the invention are characterized in the subclaims.

In an advantageous development of the throttle according to the invention it is provided that the first winding is wound near the core and the second winding is wound over the first winding. The turns of both windings should be in the ratio 1: 1; wherein the RF strand is shown solid.

In a further advantageous embodiment of the invention, the individual turns of the second winding are arranged exactly in alignment over the corresponding turns of the first winding. During the manufacture of the reactor, the core-near HF winding is wound up first. Thereafter, in a second production step, the second winding is wound up. A stable fixation of the overlying second winding results, if it is ensured that exactly aligned over the corresponding RF strand, the corresponding z. B. vertical winding is provided. Again, a ratio of turns of 1: 1 is taken into account.

In order to better eliminate current displacement effects and to further increase the efficiency, it is furthermore advantageous if the first winding consists of stranded strands and in particular stranded individual strands. The RF strand is stranded, which means that the RF strand is twisted in itself. In this advantageous embodiment, a rotation of 360 ° over a winding length, to ensure that each wire of the strand during a turn comes at least once as close to the magnetic field or the core. This is an important feature in addition to the division of the current in an HF component and a DC component, which flows in the massive edgewise winding.

As already mentioned, the second winding may consist of at least one cross-sectionally rectangular, in particular high-pitched, wire sitting on the strand. This solution results in optimum winding utilization and a very high copper fill factor. A winding should be done with a single layer. A single-layer winding is less capacious. In addition, there is a better EMC (electromagnetic compatibility) and a much more uniform heating and better heat conduction, which is why the cooling is more advantageous. In addition, there are fewer losses due to the vertical position of the rectangular winding. This is because then the alignment of the magnetic field line in the conductor is better than with the horizontal orientation of the rectangular winding.

The diameter of the individual cores depends on the choke frequency. The number of individual cores defines the total cross section of the HF strand.

Thus, alternatively, the second winding also consist of at least one cross-sectionally circular, sitting on the strand wire. In particular, the second winding consists of two wires arranged one above the other, for example round wires. Also, three or more windings are not excluded in principle. Likewise, stacked square conductors are possible.

A particularly preferred embodiment of the invention is characterized in that the core is designed as a U- or E-shaped core with an air gap, wherein preferably the air gap is divided into several air gaps. A significant advantage results from the division into several partial air gaps. For an E-shaped core, this means that the web in the center of the E-shaped core has several horizontal separations (cuts), ie several air gaps, with several smaller, narrower air gaps cause lower losses than a large air gap. To achieve optimum efficiency, however, it may also be provided to grind the material of the core, d. H. This gives a sintered powder, which is pressed together after its grinding and optionally cast with a synthetic resin. There are then a large number of air gaps, which leads to the lowest possible losses.

An embodiment will be explained in more detail with reference to the drawings, wherein further advantageous developments of the invention and advantages thereof are described.

Show it:

1 a choke with a choke winding according to the invention,

2 an enlarged view of a cross section of the RF choke winding according to 1 .

3 a detailed view of the RF choke winding,

4 an enlarged view of a cross section of the throttle coil according to 1 .

5 a circuit arrangement of the first and second winding,

6 3 is an enlarged view of a cross section of the second, upper inductor winding according to an alternative embodiment,

7 a throttle with an E-shaped choke core,

8th a throttle with a U-shaped choke core,

9 a single air gap of a throttle core, and

10 an air gap of a throttle core, which is divided into several air gaps.

1 shows a throttle 1 with a choke core 2 and a choke winding 3 around the choke core 2 is wound.

The throttle 1 is an electrical component to produce a defined inductance. For example, the throttle 1 be used to store electrical energy for a short time or to fulfill a filter function. An example of energy storage is a DC-DC converter in which a DC voltage is changed by switching operations and by means of the choke. Another example is filter functions in which harmonics of a line frequency are filtered.

According to the invention, the throttle winding 3 in a first winding 4 and a second winding 5 divided up. These are connected in parallel.

Further illustrated 1 that the first winding 4 near the core 2 is wound and the second winding 5 over the first winding 4 is wound and that the individual turns of the second winding 5 exactly aligned over the corresponding turns of the first winding 4 are arranged.

As 2 illustrates is the first winding 4 designed as a stranded winding in which the individual stranded wires 6 individually electrically isolated. The first winding consists of stranded strands 10 , As the arrow should show, the strand is 10 twisted, so that a rotation of 360 ° over a winding length takes place. Thus, each wire of the strand during one turn comes very close to the magnetic field at least once.

3 shows three of the plurality of stranded wires 6 , Every stranded wire 6 has a stranded conductor 7 with an enveloping electrical insulation 8th ,

In the 4 enlarged illustrated second winding 5 is considered a massive winding with a massive conductor 9 executed. It can also have insulation. Massive means they are not made of strands 10 consists. The second winding 5 exists after the in 4 shown variant of at least one rectangular in cross section and hochtkant on the strand 10 sitting wire 6 ,

A division into a first winding 4 and a second winding 5 means electrically that both windings 4 . 5 are electrically connected in parallel, such as 5 shows. Part of the inductor current I1 flows through the first winding 4 while another part of the inductor current I2 through the second winding 5 flows. Here, the first winding as HF Litze used while the second winding is provided as a DC winding, so that the current flowing through the inductor substantially into an HF component (I1) and a DC component (I2), wherein the first, stranded winding 4 is provided substantially for the HF component (I1), while the second, massive winding is provided essentially for the DC component (I2). The turns of both windings as turns 4 and 5 are in a winding ratio of 1: 1 to each other.

Due to the skin effect and other effects is another power split the ladder 6 and 7 with respect to alternating or HF current available. Decisive is now not only the aspect ratio, but the frequency and geometry dependent current displacement. Thus, a much higher proportion of alternating current flows through the conductors 7 (I1) than in the DC case. It is best if a higher alternating current through the conductors 7 flows as through the conductor 9 , Each of the ladder 7 and 9 carries both a DC component and an AC or an HF component.

In 6 a variant of the invention is shown. This is the second winding 5 from at least one cross-sectionally circular, sitting on the strand wire. In this case, there are two round wires arranged one above the other 11 . 12 available.

7 shows an E-shaped core 2 , The choke core 2 consists here of magnetic field lines well conductive material, such as iron. The E-shaped core has a central web 15 and as a yoke two side bars 16 . 17 , The throttle 1 is such that the middle bridge 15 in the middle of the windings 4 . 5 is surrounded.

8th shows a U-shaped core 2 , In this core form have two opposite outer walls 18 . 19 the windings 4 . 5 on.

As in 9 shown is the core 2 with an air gap 20 executed. With the reference number 21 the corresponding magnetic field lines are marked in the gap region. Through the air gap 21 the inductance can be defined or the choke 1 be measured and the number of turns are determined.

In 10 a solution is shown in which the air gap in several air gaps or partial air gaps 22 . 23 . 24 is divided. The individual core parts in the area of the air gaps are the same or have the same size.

A variant not shown is that the material of the core consists of a milled material, preferably of a sintered powder, which is compressed after its grinding. The choke is particularly suitable for inverters, switching power supplies or PFC stages.

In particular, in this connection, it should be noted that in order to make a choke efficient, it is advantageous if the yoke has a lower magnetic resistance than the limb (s), the limb preferably carrying the coil. This can be achieved, on the one hand, by arranging one or more air gaps distributed in the core in the winding area in the region of the winding.

In the case of a core made of sintered powder, the powder can be selected as the material mix in such a way that a large number of small air gaps are formed in the region of the winding, for example by choosing a coarser grain size of the powder.

The invention is not limited to this example, so the winding 5 rather than for a DC current for a low frequency current, e.g. B. mains frequency z. B. 50 Hz while the winding 5 a higher frequency current, z. As HF current leads. HF current is a high-frequency current that can be over 1 kHz. Also, the second winding 5 be designed as a waveguide or even be a strand without insulation. The winding 5 but preferably has a full material filled with cross-sectional area. In principle, it is also conceivable that the choke core is not made of iron, but a winding body, a base body or the like from z. B. plastic, so that the throttle is an air coil.

LIST OF REFERENCE NUMBERS

1

throttle

2

reactor core

3

choke winding

4

first winding

5

second winding

6

stranded wires

7

Stranded conductor

8th

electrical insulation

9

massive ladder

10

braid

11, 12

round wires

13, 14

15

center web

16, 17

sidebars

18, 19

opposite outer walls

20

air gap

21

magnetic field lines

22, 23, 24

Part air gaps

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3819575 A1 [0010]

Claims (10)

Throttle ( 1 ) with a throttle core ( 2 ) and a choke winding ( 3 ) around the choke core ( 2 ), characterized in that the choke winding ( 3 ) in a first winding ( 4 ) and a second winding ( 5 ), the first winding ( 4 ) as a stranded winding ( 5 ) is carried out, in which the individual stranded wires ( 6 ) are electrically isolated individually, and wherein the second winding ( 5 ) is designed as a massive winding. Throttle according to claim 1, characterized in that the first winding ( 4 ) near the core ( 2 ) and the second winding ( 5 ) over the first winding ( 4 ), wherein the winding ratio of both windings ( 4 . 5 ) is preferably 1: 1. Choke according to claim 1 or 2, characterized in that the individual turns of the second winding ( 5 ) exactly aligned over the corresponding turns of the first winding ( 4 ) are arranged. Choke according to one of the preceding claims, characterized in that the first winding ( 4 ) of stranded stranded wire ( 10 ) consists. Throttle according to one of the preceding claims, characterized in that the second winding ( 5 ) of at least one in cross-section rectangular, in particular upright on the strand ( 10 ) sitting wire ( 6 ) consists. Choke according to one of claims 1 to 4, characterized in that the second winding ( 5 ) of at least one cross-sectionally circular, on the strand ( 10 ) sitting wire ( 6 ), in particular of two superposed round wires ( 11 . 12 ) consists. Throttle according to one of the preceding claims, characterized in that the core ( 2 ) as U- or E-shaped core with an air gap ( 20 ), wherein preferably the air gap ( 20 ) into several air gaps ( 22 . 23 . 24 ) is divided. Throttle according to one of the preceding claims, characterized in that the material of the core ( 2 ) consists of a milled material, preferably of a sintered powder, which is pressed together after its grinding, wherein the material in the region of the leg or legs is chosen so that there is a greater number of air gaps, as in the region of the yoke. Throttle according to one of the preceding claims, characterized in that the first winding ( 4 ) as an HF strand while the second winding ( 5 ) is used as a DC winding, so that through the choke ( 1 ) current is divided substantially into an HF component and a DC component, wherein the first, stranded winding ( 4 ) is provided substantially for the HF component, while the second, massive winding ( 5 ) is intended essentially for the DC component. Use of a reactor according to one of the preceding claims in an inverter, a switching power supply, or in a PFC stage.

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