EP2562772A2 - Inductive unit - Google Patents

Abstract

The component has two choke coils coupled with one another by a magnetic circuit, and arranged in a common core. The common core comprises plate-shaped core intermediate elements (4, 10), which change a coupling between windings (2, 6) of the choke coils. The core intermediate elements lie in a region of an air gap (8) between two middle brackets (7, 11). The middle brackets are projected from core yokes (1, 5), which connect core brackets (3, 9). The core intermediate elements have a recess, which is adapted to a cross-section of the middle brackets.

Description

The invention relates to an inductive component according to the preamble of patent claim 1.

In automotive and energy technology, power electronics is playing an increasingly important role. In particular, in the field of inverters for photovoltaic systems in recent years, a steadily growing market has developed. But not only the stationary application in the power generation, but also the mobile use of the electronic current and voltage conversion will increase further in the next years. Decisive here is the development of a new hybrid generation and everyday electric vehicles.

Regardless of their use, inductors for power electronics are an indispensable component, without which, for example, a DC-DC conversion in the higher power range is difficult to imagine. High frequency transformers as well as storage and filter chokes are used.

In essence, in the dimensioning of such inductances always an optimal solution between available space, given electrical data and the lowest possible losses must be found. In the automotive industry is also a low weight with otherwise the same performance data advantage.

The invention is based on an E-shaped core, in which, for example, two secondary chokes of a full bridge converter are combined with Stromverdoppler, which has the advantage that not, as before, two separate chokes are needed. This not only reduces the installation space, but also reduces the weight, which also reduces costs. The combination of two reactors, however, it is necessary to realize a corresponding leakage inductance, which encounters difficulties with a simple E-core, since coupling factors of more than 0.9 are already achieved without major interleaving of the windings. This value can be increased by a corresponding winding structure. If, however, lower couplings of z. B. 0.8, it becomes difficult to realize this with a simple E-core.

Subject of the DE 22 26 289 A1 is a premagnetized magnetic core, which requires the use of a permanent magnet. In the exemplary embodiment of FIGS. 3C and 3D, permanent-magnetic platelets are used to increase the saturation in the vicinity of an air gap.

Out US 2011/0140817 a superconducting coil is known, which requires the use of superconducting material. The ferrite plates shown in the example of FIG. 5B serve to guide the magnetic field more precisely; They should avoid that the magnetic flux passes through the material of the windings and thus a reduction of the function is suppressed at critical currents, which also reduces the losses.

In DE 24 24 131 A1 a reactor is described and illustrated which includes a permanent magnet in a portion of its magnetic circuit for use in saturation magnetization.

The invention has for its object to provide an inductive component in which it is possible to change the coupling between two or more windings.

The solution to this problem arises from the features of claim 1. Advantageous developments are the subject of the dependent claims.

In the inductive component according to the invention, two or more windings of a throttle are coupled together by a magnetic circuit, wherein the magnetic flux controlled by inserted, preferably plate-shaped core intermediate elements and depending on the application, the coupling can be adjusted. This does not necessarily mean that there is a rigid E-core shape. Rather, the inventively provided technology of Use core interface elements in other core geometry, such as EC, EFD, EP, EQ, ER or EFD cores.

The invention is explained below with reference to an embodiment which is shown in the drawing. This shows the basic structure of a choke with E-core and two windings.

The throttle has two core yokes 1, 5, the two core legs 3, 9 connect together and two center legs 11, 7 each carry a winding 2, 6. The two center legs 11, 7 are here separated by an air gap 8. The two windings 2, 6 are traversed by an electric current and thus generate a magnetic flux which passes through the two center legs 7, 11. About the two core legs 3, 9 and core yokes 1, 5, the magnetic circuit is closed. As a result, the flux density of the central limb is split in half on the core limbs and core yokes, which are approximately half as large in cross section.

Due to a saturation behavior required in most applications, an air gap 8 is required. This guarantees that the inductance value of z. B. 10 μH even at a higher operating current of z. B. 50 A is available and does not drop to about 1 uH. The inductance of a choke with ferrite core drops very rapidly at the saturation limit, even with a relatively small current change. In the worst case, this can destroy the semiconductors of the circuit. Therefore, the throttle should not exceed this limit in any operating conditions.

According to the invention, two plate-shaped core intermediate elements 4, 10 are used in the throttle, which are attached to the respective core leg 3, 9 and projecting parallel to the core yokes 1, 5 in the direction of the air gap 8. The core intermediate elements 4, 10 are made of the same material as the remaining part of the core, which is preferably formed as a soft magnetic ferrite core, while copper is used as a conductor material for the windings 2, 6 of the choke coils.

At its free ends, each intermediate plate 4, 10 has a part-circular recess, which is adapted to the radius of the two center legs 7, 11. In differently shaped middle limbs, the recess has a shape adapted to this.

The core intermediate elements 4, 10 serve to direct the magnetic flux targeted. This creates a stray flux, but in contrast to the main flow for the most part only one winding passes through.

berechnet werden. Dabei beschreibt Lg die Gesamtinduktivität, wenn beide Wicklungen in Reihe geschaltet sind, und L₁ sowie L₂ die Induktivität der einzeln gemessenen Wicklungen 2, 6. Zudem kann auch über die Streuinduktivität das Ausmaß der Kopplung bewertet werden. Hierzu muss eine Wicklung kurz geschlossen und bei der anderen die Induktivität gemessen werden. Je höher diese Streuinduktivität ist, desto schlechter sind die beiden Wicklungen gekoppelt.The coupling of the two windings 2, 6 can by the formula $$\mathrm{k}\mathrm{=}\mathrm{½}\left({\mathrm{L}}_{\mathrm{G}}\mathrm{-}{\mathrm{L}}_{\mathrm{1}}\mathrm{-}{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="imgf0001.png"\; state="\{\{state\}\}">L</figure-callout>}}_{\mathrm{2}}\right)\mathrm{,}{\left({\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="imgf0001.png"\; state="\{\{state\}\}">L</figure-callout>}}_{\mathrm{1}}{\mathrm{L}}_{\mathrm{2}}\right)}^{\mathrm{-}\mathrm{1}\mathrm{/}\mathrm{2}}$$

be calculated. In this case, Lg describes the total inductance when both windings are connected in series, and L ₁ and L _2, the inductance of the individually measured windings 2, 6. In addition, the extent of coupling can also be assessed via the leakage inductance. For this, one winding must be short-circuited and the other inductance measured. The higher this leakage inductance, the worse the two windings are coupled.

The core intermediate elements 4, 10 allow by varying the distances to the center leg 7, 11 to influence the value of the leakage inductance targeted and thus to control the coupling between the two windings.

Claims (9)

Inductive component having at least two mutually coupled by a magnetic circuit reactors, which are arranged in a common core, characterized in that the common core at least one the coupling between the windings (2, 6) of the choke coils changeable core intermediate element (4, 10) , Inductive component according to claim 1, characterized in that the core intermediate elements (4, 10) are removably mounted in the core. Inductive component according to claim 1 or 2, characterized in that the core intermediate elements (4, 10) and the core of the same material, preferably ferrite. Inductive component according to one of the preceding claims, characterized in that the windings (2, 6) of the choke coils consist of copper. Inductive component according to one of the preceding claims, characterized in that the core intermediate elements (4, 10) each protrude from a core limb (3, 9) in the direction of a central leg (11, 7) carrying a winding (2, 6). Inductive component according to Claim 5, characterized in that the core intermediate elements (4, 10) lie in the region of an air gap (8) between two center limbs (11, 7). Inductive component according to claim 5 or 6, characterized in that the central limbs (11, 7) protrude from a core yoke (1, 5) connecting the core limbs (3, 9). Inductive component according to one of the preceding claims, characterized in that the core intermediate elements (4, 10) are plate-shaped. Inductive component according to claim 8, characterized in that the plate-shaped core intermediate elements (4, 10) have at their free end a to the cross section of the center leg (11, 7) adapted recess.

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