WO2008083693A1 - Production method for an electrical inductor - Google Patents

Abstract

The invention relates to a method for winding coils for electrical inductors for example for high-power DC/DC convertors. According to the invention, both coil elements of an inductor are manufactured in one winding operation without any interruptions from the same copper strip by the copper strip (7) being wound onto coil formers (8a, 8b) from both ends. This produces a "double coil" (10), which is distributed with the correct winding sense between two coil formers.

Description

 Production process for electric throttle

The invention relates to methods for winding coils on soft magnetic cores. Specifically, the invention relates to winding coils for electric reactors, e.g. for high-performance DC / DC converters.

Chokes are u.a. used in power supply units. They suppress unwanted ripple in the DC circuit, which are generated in particular by upstream converters. Figure 1 shows an arrangement according to the prior art. For chokes for high power density DC / DC converters, two coils (1, 2) are individually wound on a core (3), e.g. is designed as a laminated core. The two terminals (4a, 4b; 5a, 5b) of each coil are led out separately and two of them are externally connected to the throttling action, e.g. by means of solder joint (6) or contact terminal, connected together.

The disadvantages of this solution consist in a more complex production, since in addition to the actual winding process in a subsequent process step, the external coil connection must be made. In addition, this technique requires more space (more solder joints, insulation of the connection) and can also lower reliability by itself pull. In many cases, the external connection (terminal, solder joint) is an optimal cooling connection in the way.

Considerations to minimize the effort in winding processes are described. Thus, published patent application DE10056794A1 relates to a method for producing a stator winding for an electrical machine. In this case, different groups of identical, serially connected coils are wound uninterrupted with a wire of predetermined cross-section, wherein an additional partial coil is provided in each group.

The invention is based on the aforementioned document as the closest prior art. It has the object to develop an improved process for the production of throttles, which has technical advantages over the previous procedure.

This object is achieved in a method having the features of the preamble of claim 1 by the characterizing features of claim 1. Further details and advantageous embodiments of the device according to the invention are the subject of the dependent claims. •

The invention will be explained in more detail below with reference to a preferred embodiment with reference to the figures and the reference numerals therein. Showing:

Fig. 1 perspective view of a throttle according to the prior art with two bobbins

Fig. 2 Scheme of the winding method according to the invention Fig. 3 section through a wound by the process according to the invention throttle

Fig. 4 perspective view of a wound with the method according to the invention throttle

Fig. 5 coil according to the inventive method with smoothing of the edge region by surface grinding / -

Fig. 6 insulation of the windings in the edge region of a coil by etching and sealing

In electric reactors, whose core is not designed as a toroidal core, copper sheet or copper foil is used very often instead of wire. This offers a number of advantages compared to normal round wire. Thus, the influence of the skin effect is significantly reduced compared to the cross section due to the larger circumference. The wide sheet also results in a significantly higher copper filling factor. This in turn offers better heat dissipation due to the higher heat flux through more copper.

The invention proposes to manufacture both partial coils without interruption from the same copper strip in one winding cycle. Figure 2 shows schematically the winding process. In this case, the copper strip (7) from both ends on the bobbin (8a, 8b) or bobbin (9) wound. When the winding directions are selected as shown in Fig. 2, the winding sense with respect to the respective bobbin is maintained. As shown in Figure 3 as a section, the result is a "double coil" (10), with proper winding direction is distributed to two bobbin (8a, 8b), or bobbin (9). Due to the uninterrupted winding, only the two connections (4a, 5a) of the throttle are led out.

In this case, for winding each directly either a bobbin (8a, 8b) can be used (eg as shown in Fig. 3 as a stack of iron sheets) on which the coil remains later and via a corresponding bridge (magnetic flux) with the second bobbin is assembled to the throttle. Alternatively, for the winding process, a coil carrier (9), e.g. plastic, used e.g. is designed as a hollow profile and can be pushed onto a throttle body of iron sheets.

With appropriate stability (compact winding, e.g., by potting), the coils (10) can also be from the bobbins

(9) are withdrawn and pushed onto a throttle body. It is thus also possible to use throttles with E-cores with the double coils wound by the method according to the invention

(10).

In Figure 4, the fully assembled throttle is shown. Chokes are to be cooled for continuous operation under high load. This requires an outer shape with which a good thermal connection to one or more heat sinks can be achieved, wherein the heat sink can be water or air cooled. Since the inventive method reduces external wiring areas (elimination of the solder joint (6), or terminal), the throttle core can be attached to a heat sink in this area (13). With appropriate design and construction of the heat sink can also be tied to the package of copper strip of the coil (9). In an advantageous embodiment of the method according to the invention, the edge regions (11) of such a coil are additionally treated. Thus, in a compact coil (10) a smooth surface in the edge region (11) can be produced by surface grinding, milling or the like. This is shown as a section in FIG. So that a reliable insulation is achieved even in this particularly critical area, parts of the exposed copper strip (7) can be etched following the aforementioned surface grinding, milling or the like and anschießend with insulating material (12), for example, synthetic resin, etc., shed. This is shown schematically in FIG. By such a final treatment of the winding head can be achieved in the long term secured stability of the throttle.

The inventive method can be produced with reduced production costs very compact chokes that can achieve high performance with small dimensions.

Claims

claims 1. A process for the production of electric reactors with coils (1, 2) on a choke core (3), characterized in that the coils (1, 2) in a winding cycle without interruption from a copper strip (7) are made by the copper strip of Both ends are wound on bobbin (8a, 8b) or bobbin (9), so that from the coils (1, 2) a double coil (10) is formed. 2. The method according to claim 1, characterized in that the coils (1, 2) are wound on a coil carrier (9), which is designed as a hollow body. 3. The method according to claim 1 or 2, characterized in that in a further process step, the coils (1, 2) are smoothed in the edge region (11), e.g. by surface grinding, milling or the like, and parts of the thus exposed copper strip (7) e.g. be removed by etching and then the edge region (11) by means of insulating material (12) is sealed.