EP1916675A1 - Coil comprising several coil branches and micro-inductance comprising one of the coils - Google Patents

Abstract

The winding has a set of disjointed loops (1), each having a rectangular lower flat section (4) in a lower plane and a rectangular upper flat section (5) in upper plane, inner plane up section (6) and outer plane up section (7). The loops fill a covering surface of the winding, and a minimum isolation space (2) separates the adjacent loops. The section (6) is narrow than that of the section (7), and the upper and lower flat sections expand towards the outside of the winding. The sections (4, 5) corresponding to a same loop have same shape.

Description

Technical field of the invention

The invention relates to a winding comprising a plurality of disjoint turns constituting a plurality of substantially parallel winding branches, each winding having a rectangular lower plane section in a lower plane, a rectangular upper plane section in an upper plane and two rising sections. , the rising sections of two adjacent branches disposed between the two adjacent branches being arranged alternately in a single plane.

State of the art

The invention is part of the theme of integrated micro-inductors for applications in power electronics. It can, more generally, apply to all inductive systems integrated or not (inductors, transformers, magnetic recording heads, actuators, sensors, etc ...) requiring a high density of electrical power.

For many years there have been micro-inductances of various types. However, the discrete components remain very predominantly used in applications using high power densities because only these allow to use very thick winding son to achieve very low levels of electrical resistance. Most of the micro-inductors used on the market are discrete components manufactured by micromechanical processes of micro-machining, gluing, micro-winding, etc. These processes are difficult to implement. work, individual treatment, flexible in terms of design and greatly limit the miniaturization of power circuits. In particular, the thickness of the discrete micro-inductors (typically greater than 0.5 mm) does not allow appropriate packaging in the power supply circuits currently used for mobile telephony, for example.

The manufacturing techniques used in microelectronics allow a much greater flexibility in the implementation of different designs, provide a collective treatment and are compatible with the idea of miniaturization because the thickness (including substrate) can easily be less than 300 μm. However, they are poorly suited to deposition of high thicknesses (greater than 10 .mu.m) of conductive, magnetic or dielectric materials and to their etching after photolithography.

For integrated components, there are constraints of technological achievement. Indeed, deposits of conductive layers having a thickness greater than 100 microns are currently not feasible in a standard industrial process.

Micro-inductances of the toroidal solenoid type have a good compromise between losses and level of inductance because they approach the ideal case of the infinite solenoid.

Article Numerical Inductor Optimization by A. von der Weth et al. (Japan Magnetic Trans., Vol.2, No.5, pp.361-366, 2002). ) discloses a micro-inductance with an open magnetic circuit composed of a plurality of parallelepiped cores. A plurality of disjoint turns constitutes a winding around the branches of the magnetic core. Each turn has a lower plane section in a lower plane, an upper plane section in an upper plane and two rising plane sections.

The rising sections of two adjacent branches disposed between the two adjacent branches are arranged alternately in a single plane, which provides a small spacing between two adjacent branches. The compactness of the device can thus be increased. For these devices, it is sought to increase the level of inductance and to minimize losses.

Object of the invention

The object of the invention is to improve the performance of a micro-inductor, while increasing the compactness of the micro-inductance.

According to the invention, this object is achieved by a winding according to the appended claims and more particularly by the fact that the upper and lower sections corresponding to one and the same turn are aligned with respect to one another and having a width greater than the width of the corresponding rising sections disposed between two adjacent winding branches, the turns fill almost all of the envelope surface of the winding, a minimum isolation gap separating the adjacent turns.

Brief description of the drawings

• les figures 1 à 3 représentent un mode de réalisation particulier de l'invention, respectivement en vue de perspective, en vue de dessus et en coupe vue de dessous selon le plan défini par les deux axes A-A et B-B de la figure 2,
• la figure 4 représente, en vue de perspective, un autre mode de réalisation particulier de l'invention.

Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention given by way of non-limiting example and represented in the accompanying drawings, in which:

• FIGS. 1 to 3 represent a particular embodiment of the invention, respectively for perspective, in top view and in cut from below according to the plane defined by the two axes AA and BB of FIG. 2,
• Figure 4 shows, for perspective, another particular embodiment of the invention.

Description of a preferred embodiment of the invention

The different types of winding described below can be made without necessarily using a magnetic core. Preferably, however, the coil wraps around a magnetic core.

The winding shown in Figures 1 to 3 comprises a plurality of turns 1 spaced apart from each other by a minimum separation gap 2 separating adjacent turns 1. The isolation gap 2 is set by the constraints of technological achievement and the desired electromagnetic behavior. The turns 1 constitute a winding around a magnetic core 3 having four parallel branches 11 (11a, 11b, 11c, 11d). One could also consider the same winding without magnetic core or with an open core. The plurality of disjointed turns 1 constitute a winding around substantially parallel branches 11 of the magnetic core 3. When this coil is used without a magnetic core, the disjoint turns 1 constitute a plurality of substantially parallel winding branches.

Each turn 1 has a lower plane section 4 in a lower plane, an upper plane section 5 in an upper plane and two rising planar sections 12 and 13. It should be noted that these four elements (the lower plane section 4, the plane section upper 5 and the two planar rising sections 12 and 13) are not connected together so as to form a loop as, for example, in the case of a winding classical solenoid. Indeed, the flat sections 4 and 5 may belong to separate electrical conductors, each electrical conductor passing from the lower plane for a predetermined branch to the upper plane for an adjacent branch and vice versa. The turns 1 fill almost all the envelope surface of the winding, with the minimum isolation gap 2 near.

The envelope surface of the coil means a continuous surface delimited by the coil and connecting the adjacent turns to each other. The envelope surface of the winding thus includes turns 1 and isolation gaps 2. This envelope surface of the winding must be filled to the maximum by the turns 1, the isolation gap 2 serving only to ensure the electrical insulation between the turns 1. The isolation gaps 2 can, moreover, be filled by a material insulating.

Thus, in FIG. 1, the turns constitute a quasi-total envelope of the branches of the magnetic core 3. Unlike the devices of the prior art, the micro-inductor uses all the space potentially available for winding and leaves no room for unused space. The micro-inductance thus has a lower resistance for a predetermined size.

The thickness of the winding is a compromise between the ease of realization and the desired level of resistance.

The rising sections 12a and 12b of two adjacent branches 11a and 11b disposed between the two adjacent branches 11a and 11b are arranged alternately (12a, 12b, 12a, 12b, ...) in a single plane. In the particular embodiment shown in Figure 1, this single plane is perpendicular to the plane of the magnetic core 3 and passes through the axis CC which passes through the rising sections 12a and 12b. The turns 1 constitute an almost total envelope of the branches 11 of the magnetic core, a minimum isolation gap 2 separating adjacent turns 1.

Thus, the turns 1 fill almost all the envelope surface of the winding, the winding being constituted by several winding branches, with or without magnetic core.

The upper 5 and lower 4 sections represent, given their size, the bulk of the surface of the turns. Thus, while the length Lm (FIG. 1) of the rising sections 12 is, for example, of the order of 20 microns, the length Ls of the lower 4 and upper sections 5 is, for example, of the order of several hundred microns. The upper 5 and lower 4 sections preferably have a substantially rectangular shape (see FIGS. 1 to 4), to which are added connections to the rising sections 12. The upper section 5 advantageously has the same dimensions and, preferably, the same shape as the lower section 4 corresponding to the same turn 1 and they are preferably aligned relative to each other. Thus, they are superimposed completely, that is to say their projections in a plane parallel to the upper sections 4 and 5 are the same.

In Figures 1-3, the upper sections 4 and lower 5 have a width greater than the width of corresponding rising sections 12a and 12b disposed between two adjacent branches 11a and 11b. The width of the rising sections 12a and 12b disposed between two adjacent branches 11a and 11b is preferably less than half the width of the upper and lower sections 4 to allow entanglement of the turns at the crossings between the turns. . Thus, the upper 5 and lower 4 sections have a width greater than the sum of the widths of the corresponding rising sections 12 disposed between two adjacent winding branches. Advantageously, the rising sections 12a and 12b have the same surface.

The rising sections 13 disposed outside an outer branch 11a of the micro-inductor may have the same width as the upper 4 and lower 5 sections of the corresponding turns 1 of the same branch 11a.

In Figures 1-3, the upper 4 and lower 5 sections of each turn 1 corresponding to the branch 11a (right in Figure 1) are connected by the rising sections 13 disposed outside. The upper 4 and lower 5 sections of each turn 1 corresponding to the branch 11d at the other end (left in Figure 1) of the core 3 are connected by the rising sections 12c disposed between the adjacent branches 11c and 11d. Two adjacent turns corresponding to the branch 11d at the end of the core 3 (shown on the left in FIG. 1) are connected by an upwardly mounted rising section 12d and a connection section 14 arranged in the lower plane corresponding to the sections lower 4.

The sizing of this winding can be done in the following manner illustrated in FIG. 2. The length C of the magnetic core is defined. It will be considered that all the branches of the core are of the same width WMAG. The technological and electrical constraints set the dimensions V of the rising sections 12, the inter-turn distance INT and the spacing M between the coil and the magnetic circuit. It should be noted that FIG. 2 is not to scale and that the spacing M is, thus, variable in FIG. 2. The inter-turn distance INT between two adjacent turns corresponds to the difference 2 of minimum isolation. The spacing between the branches I must be at least I = V + 2 * M. The winding can then be fully defined. The number of turns per N-branch (five in FIG. 2) is determined by the desired level of inductance. The WMAX width of the upper 5 and lower 4 sections is calculated according to the formula WMAX = (C-2 * WMAG- (N-1) * INT-2M) / N. The width WMIN of the rising sections 12 is calculated according to the formula WMIN = (WMAX-INT) / 2. The thickness of conductive material is finally fixed as a compromise between the ease of realization and the desired level of resistance.

FIG. 4 illustrates a micro-inductance with a substantially annular closed magnetic core 3 of which only two parallel branches 11 are covered by a winding constituting an almost total envelope of the two branches 11. The same type of winding as that previously described can be used.

The particular embodiment makes it possible to improve the performance of the inductive systems and in particular to increase the inductance of the micro-inductance and the compactness of the winding.

In the particular embodiment described, the turns constitute an almost complete envelope of the magnetic core on the entire parallel branches of the multi-branch core. Only the minimum isolation gaps 2 separate the lower planar sections 4 from two adjacent turns, the upper planar sections 5 from two adjacent turns and two adjacent rising sections. The minimum isolation gap 2 depends on the manufacturing technology used and the electromagnetic constraints. The gap between turns does not exceed the minimum isolation gap 2.

For the integrated components using conventional micro-manufacturing techniques, the two variants do not present any additional manufacturing difficulties compared to the conventional pre-existing systems. For example, the upper and lower sections 4 may respectively be etched in conductive layers.

Claims (6)

Winding comprising a plurality of disjoint turns (1) constituting a plurality of substantially parallel winding branches, each turn (1) having a lower plane section (4) rectangular in a lower plane, an upper plane section (5) rectangular in a plane two rising sections (12a, 12b, 13), the rising sections (12a, 12b) of two adjacent branches arranged between the two adjacent branches being arranged alternately in a single plane, the winding being characterized in that the upper sections (5 ) and lower (4) corresponding to the same turn being aligned relative to each other and having a width greater than the width of the corresponding rising sections (12) arranged between two adjacent winding branches the turns (1) fill almost all of the envelope surface of the coil, a minimum isolation gap (2) separating the adjacent turns (1). Winding according to claim 1, characterized in that the upper (5) and lower (4) sections corresponding to the same turn have the same shape. Winding according to one of claims 1 and 2, characterized in that the upper (5) and lower (4) sections have a width greater than the sum of the widths of the corresponding rising sections (12) arranged between two adjacent winding branches. Winding according to one of Claims 1 to 3, characterized in that the rising sections (13) arranged outside an outer winding leg of the winding have the same width as the upper (5) and lower (5) sections. 4) corresponding turns. Micro-inductor, characterized in that it comprises a winding according to any one of Claims 1 to 4. Micro-inductor according to claim 5, characterized in that it comprises a magnetic core enveloped by the winding.

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