KR20180095030A - Inductance circuit with passive thermal management - Google Patents

Abstract

The present invention relates to an inductance circuit comprising a) a frame (21) and a bar (30) arranged in the center of the frame (21), the inductance circuit being symmetrical with respect to the bar (30) A bar 30 disposed in the center of the frame 21 adjacent to the symmetry plane of the bar 30 and forming two rectangular magnetic loops having an effective magnetic length l, An integrated core (20) made of a magnetic material including a cross section having a region (A); b) a coil (40) comprising a winding (N); c) a pin 50 that is exposed to the external environment and intended to dissipate heat; Wherein the inductance circuit is configured such that the pin is included within at least one volume section of the frame and forms an extension of at least one end of the bar .

Description

Inductance circuit with passive thermal management

The present invention relates to an inductance circuit comprising a single-piece core comprising a passive temperature regulation system.

Figure 1 shows an inductance circuit known in the prior art and described in U.S. Patent No. 6,920,039 B2,

characterized in that it comprises a) a frame (2) and a bar (3) located at the center of the frame (2), which is symmetrical with respect to the bar (3) and which is adjacent to the symmetry plane of the bar (3) located at the center of the frame (2), the straight portions of the magnetic loops having a cross-section with an area (A), forming two rectangular magnetic loops A core (1) made of a single-piece magnetic material having a total volume (V);

b) a coil (4) comprising N windings around said bar (3);

c) a pin (5) designed to be exposed to external environment and to dissipate heat;

.

The pin is added on the outer surface of the core (1).

The induction circuit has an inductance (L) determined by magnetic permeability (μ _r ) and size (A, 1, N) of the core (1)

Lt; / RTI >

In other words, the geometry of the core 1, in particular the ratio of the geometrical factors 1, A, determines the inductance value of the inductance circuit.

This inductance circuit can be used, for example, in a power converter, and the function of the power converter is to adapt the voltage and current output by the power supply to power the electrical system.

The power converter also includes an electronic component that acts as a switch (active part) that switches at a given frequency f, resulting in power to the exciter coil 4. [

For example, in the case of a DC / DC converter, the active component is a transistor used to "chop" the input voltage with a certain cycle. To output the dc output voltage, an inductance circuit is also used to store and restore electrical energy in each cycle and to smooth the output voltage to its average value.

In operation, the current output by the active component passes through the excitation coil (4), resulting in a magnetic flux comprising two symmetrical closed loops in the core (1).

2, the magnetic flux originates from the bar 3 along the axis of symmetry and flows symmetrically from one end of the bar 3 in the frame 2, Return to the end.

The inductance circuit may occupy up to 40% of the cost and volume of the transducer.

The volume of the inductance circuit can be reduced by using a magnetic core which, for having a high magnetic permeability (magnetic permeability), for example, includes a μ _r> 50 materials. Among the magnetic materials having a high magnetic permeability, ferrite type oxides, more specifically, Mn _{1 -x} Zn _x Fe ₂ O ₄ and Ni _1-x Zn _x Fe ₂ O ₄ can be mentioned.

The volume of the inductance circuit may be reduced by increasing the operating frequency of the inductance circuit. For example, the active component may comprise a transistor made of gallium nitride (GaN). These transistors can achieve switching frequencies higher than 1MHz. In this regard, a typical descriptor can refer to the literature [2] by A. M. LEARY.

The magnetic flux passing through the core (1) is accompanied by a magnetic loss which causes heating of the core.

Such heating of the core can lower the performance of the inductance circuit and consequently lower the performance of the inductance circuit.

The use of magnetic material to form the high permeability core and / or a decrease in the core volume, which is made possible by increasing the operating frequency of the inductance circuit, adds to this temperature rise.

Thus, heat dissipation means is added to the inductance circuit to better manage the amount of heat generated during operation of the inductance circuit.

The heat dissipating means as shown in Fig. 1 is disposed outside the core 1 and is added on the outer surface of the core 1 to increase the exchange surface area between the core 1 and the ambient air, ). ≪ / RTI >

As a result, the disposed pin 5 does not change the geometrical factor of the core 1, so that the value of the magnetic inductance of the inductance circuit is not changed. However, such a heat dissipating means is not satisfactory. The volume occupied by the heat dissipating means is added to the volume of the inductance, and the mass thereof is also increased. Also, for the sake of efficiency, the pin 5 must have a large exchange area and consequently occupy a relatively large area compared to the core.

For some applications, however, it is desirable or even necessary that the inductance circuit with the heat dissipating means occupy the smallest possible volume.

Thus, the inductance circuitry requires heat dissipation that operates as efficiently as is known in the highest level of technology, especially in the aerospace and automotive fields.

More specifically, the management of heat dissipation can also be optimized for the use of a magnetic core 1 with a permeability greater than 50, and / or for induction circuits that require the operation of inductive circuits at higher frequencies, for example at higher frequencies than 1 MHz .

It is an object of the present invention to disclose an inductance circuit having more efficient heat dissipation means while limiting the increase in the volume and mass of the inductive circuit.

Thus, an object of the present invention is achieved by an inductance circuit,

a) a frame and a bar located at the center of the frame, the bar being symmetrical with respect to the bar and adjacent to a symmetry plane of the bar, and forming two rectangular magnetic loops having an effective magnetic length (l) Wherein the straight portions of the frame have a cross section with an area A and the bars have a total volume V comprising a cross section 2A which is twice the cross section A. A core made of a single-piece magnetic material;

b) a coil comprising a winding (N) designed to produce magnetic induction within the bar;

c) a pin designed to be exposed to an external environment and designed to dissipate heat, the pin being made of the same magnetic material as the core;

/ RTI >

The pin is at least partially within the volume of the frame and is located along an extension of at least one end of the bar.

The inductance of the inductance circuit is equal to the nominal inductance L defined by the magnitude (A, I, N) when there is no pin in at least a portion of the frame volume.

Also, in operation of the pinless induction circuit, the magnetic induction line also passes through at least one volume.

The cross section of the straight portion of the frame is the same for each straight portion and is rectangular.

Unlike the highest level of technology, the pin is consequently in the volume of the core that is involved in the circulation of the magnetic induction line.

Applicants have observed that there is a very weak region of localized magnetic induction and that this region makes a very small contribution to the magnetic properties of the inductance circuit. The Applicant therefore proposes to use one of these zones in the core to form the pin. With this arrangement, Applicants achieve a significant degree of cooling. For example, Applicants have observed that the presence of a pin according to the present invention can change the temperature of the circuit core during operation from 250 ° C to 110 ° C. Also, the presence of the pin has little or no effect on the inductance of the inductance circuit compared to the nominal inductance.

Thus, the pin is formed directly in the volume of the core. The fin can also be formed without adding any material, and consequently can be formed without changing the volume occupied by the core.

Also, the placement of the pin, which is within the volume of the core and positioned along the extension of the bar, can create a heat exchange surface very close to the hottest zone of the core.

Further, there is no limit to the operation of the inductance circuit at frequencies higher than 1 MHz. The temperature increase due to the increase in frequency is fully managed by the pin according to the invention.

According to one embodiment, the pin is located at the bottom of at least one recess formed in at least one volume area of the frame, the at least one recess facing the outer surface of the frame, And passes through the frame from one side to the other along a direction perpendicular to the plane of the frame.

Thus, the shape of the recess results in more efficient venting of the fin and consequently better cooling of the core.

According to one embodiment, the at least one recess tapers outwardly from its bottom to the outer surface of the frame.

According to one embodiment, said at least one recess has a cross-section parallel to the plane of said frame with a certain dimension along a direction perpendicular to the plane of said frame, said cross-section being preferably trapezoidal, It is an isosceles trapezoid.

According to one embodiment, the fin is made such that the relative difference between the inductance of the inductance circuit and the nominal inductance L is less than 5%, preferably less than 2%.

According to one embodiment, at least one volume region is a region where the local magnetic inductance is less than 5% of the average value of the magnetic inductance in the core when the inductance circuit is in operation.

According to one embodiment, the pin is parallel to the plane defined by the frame.

According to one embodiment, the area developed by each fin is 10% to 100% of area A.

According to one embodiment, the pin located in the at least one volume region does not change the volume occupied by the frame.

According to one embodiment, additional pins are added on the outer surface of the frame.

According to one embodiment, the cross-section of the bar is square and the cavity passes from side to side along a direction perpendicular to the plane of the frame, the cavity being filled with an electrical conductor to form part of the coil .

According to one embodiment, the space between the fins is filled with a metal material selected from a metal material, preferably aluminum and copper.

The invention also relates to a power converter comprising the inductance circuit.

The present invention also relates to a method of manufacturing an inductance circuit,

a) creating a theoretical map of magnetic flux lines in the core of said inductance circuit in operation, said inductance circuit having a predetermined inductance value L, said core having a single piece (V) (2) having an effective magnetic length (l) and being symmetrical with respect to the bar and being adjacent to a symmetry plane of the bar, Bars located at the center of the frame, the rectilinear portions of the frame having a cross-section having an area (A), the bars having a cross-section (2A) which is twice the cross-section (A) ; ≪ / RTI >

b) using a pre-written map to identify a zone in the core volume of the inductance circuit in operation wherein the magnetic inductance is less than 5% of the average value of the magnetic inductance in the core;

c) manufacturing the core as contemplated in step a), wherein the pin is at least partly contained in at least part of a zone of the volume identified in step b), the pin also being provided on at least one end of the bar Wherein the pin is made of the same magnetic material as the core;

d) forming a coil of a conductor material around a portion of said core;

.

According to one embodiment, additional pins are added on the outer surface of the frame.

According to one embodiment, step c1) is performed after step c) to fill the space between the fins with a metallic material.

According to one embodiment, step c) of manufacturing the core is performed by powder injection molding.

Other features and advantages will be apparent from the following description of a method of manufacturing an inductance circuit according to the present invention, which is provided by way of non-limiting example with reference to the accompanying drawings.

1 is a plan view schematically showing an inductance circuit known in the prior art.
2 is a schematic diagram of a flux path in an inductance circuit known in the prior art.
3 is a plan view schematically showing an effective magnetic path of a magnetic core included in an inductance circuit known in the prior art.
4 is a plan view schematically illustrating an inductance circuit according to an exemplary embodiment of the present invention.
5 is a diagram showing a map of the magnetic induction lines in the core of the inductance circuit known in the prior art.
6A is a diagram showing a simulation of the temperature distribution in the core without any heat dissipation means known in the prior art.
6B is a diagram illustrating a simulation of the temperature distribution in the core according to one exemplary embodiment of the present invention.
7 is a plan view schematically illustrating an inductance circuit according to an exemplary embodiment of the present invention.

In each of the different embodiments, the same reference will be used for like elements or elements performing the same function, for simplicity of explanation.

Definition :

Effective magnetic length ( effective magnetic path length): Effective magnetic length L _eff is the sum of the currents passing through the circuit in which the circulation of the average magnetic field H _ave is multiplied by the nominal current I )) (Ampere's theorem). In other words, H _ave .L _eff = N * I. An example of an effective magnetic path is given in Fig. In this example, the core forms a rectangular loop and the effective magnetic path associated with this configuration is shown in dashed lines.

Cross section : The cross section is the cross section created by the intersection of the plane perpendicular to the longitudinal axis of the element with the elongated shape.

Nominal inductance (L) : Equation

The value of the inductance L defined by the effective magnetic length l, the area A, and the winding N in accordance with the following equation.

Fig. 4 shows an exemplary embodiment of the inductance circuit 10 according to the present invention. Which is an inductance circuit 10 having the geometry of the core and the inductance L _M defined by the winding N. [

The remainder of the description describes one example of the inductance circuit 10. [

An inductance circuit (10) according to the present invention includes a core (20).

The core 20 according to the present invention comprises a frame 21 and a bar 30 located at the center of the frame 21 which is symmetrical with respect to the bar 30, Bars 30 located at the center of the frame 21, adjoining and forming two rectangular magnetic loops having an effective length l, wherein the straight portions of the magnetic loop have a cross-section with a region A - < / RTI > magnetic material having a total volume (V) comprising -

The frame 21 defines a plane to be referred to as the plane of the frame in the remainder of the description. The footprint of the frame 21 (or the intersection of the frame and the plane parallel to the plane of the frame) is a rectangle having an area S.

The cross section of the straight portion of the frame 21 is the same for each straight portion, and is advantageously rectangular.

The cross-section of the bar 30 may be square, rectangular or circular.

Preferably, the core 20 comprises a magnetic material having a permeability ( _r > 50) greater than 50.

For example, the magnetic material may include a ferrite-type oxide having a spinel crystal structure. The permeability of such materials is stable within a high frequency range. The most frequently used magnetic material is represented by the following formula

Mn _{1 - x} Zn _x Fe ₂ O ₄ and Ni _{1 - x} Zn _x Fe ₂ O ₄

.

For example, the core 20 comprises Mn _{1 - x} Zn _x Fe ₂ O ₄ , where x is 0.3 to 0.6, and the permeability ( _r ) varies from x to 500 to 1000.

One preferred embodiment of the core 20 shown in the remainder of the above description includes NiZn or MnZn ferrite powder injection molding (PIM).

Preferably, the ferrite-type material has a high electrical resistance value which limits the loss due to the induced current.

Mn _{1 - x} Zn _x Fe ₂ O ₄ and Ni _{1 - x} Zn _x Fe ₂ O ₄ materials also have the advantage that they are available on an industrial scale.

The core (20) includes a frame (21) having a thickness (e). The straight portion of the frame 21 has a cross-section with the region A. [

The frame 21 also includes four outer sides forming an outer surface 22. The outer surface 22 is perpendicular to the plane of the frame.

The frame 21 includes four inner surfaces forming an inner surface 23 which is also perpendicular to the plane of the frame.

And the total volume V of the frame 21 is defined by the volume footprint. More specifically, the total volume V of the frame 21 is thus the product of the thickness e and the area S. The total volume V of the frame 21 is also equal to the total volume V 'of the core 20.

The core 20 comprises a bar 30 having a cross-section with a surface 2A (therefore the area of the cross-section with the area 2A is the cross-sectional area of the area of the cross- And two opposing sides of the inner surface 23 of the frame 21 are connected to form two symmetrical magnetic loops having an effective magnetic length l and adjacent to the symmetry plane of the bar 30. [

The bar 30 includes an axis of symmetry (represented by axis XX 'in FIG. 4) extending along its length.

Thus, the above configuration is a typical case of the core 20 used in the inductance circuit 10, where the term E-E configuration is generally used or possibly the E-E type configuration is used in two parts.

This configuration is generally obtained by assembling two half parts. Each half part includes a half frame and a half bar.

The half bars may be shorter than the two side half parts of the half frame. Thus, the bar 30 formed by the two half bars has an air gap.

The inductance circuit (10) includes an excitation coil (40) including a winding (N). When an electric current flows through the exciting coil 40, magnetic induction is generated in the bar 30. A winding N in the coil 40 may be formed around the bar 30.

The excitation coil 40 is made of a metal, for example, copper. The exciting coil 40 includes a continuous wire wound around the bar 30 to form an N-winding.

The core (20) includes a heat dissipating means.

The heat dissipating means may be in the form of a pin 50 exposed to the external environment.

Particularly preferably, the fin 50 is made of the same magnetic material as the core 20.

The fin 50 increases the external environment and the heat exchange surface area of the core 10, resulting in more efficient cooling when the inductance circuit 10 is in operation.

In accordance with the present invention, the fins 50 are at least partially within at least one volume region of the frame 21 located along an extension of at least one end of the bar 30. [

Said at least one volume zone may comprise a first volume zone 24a and a second volume zone 24b.

For example, the core is equipped with two sets of pins 50, at least partially contained in a first volume section 24a and a second volume section 24b of the frame 21. [

The first volume zone 24a and the second volume zone 24b may be disposed symmetrically with respect to a plane passing through the center of the bar 30 and perpendicular to the longitudinal axis of the bar 30. [

Preferably, the pin 50 is disposed at the bottom of the recess formed in at least one volume region of the frame 21, and the at least one recess defines an outer surface 22 of the frame 21 There is.

The at least one recess may include a first recess 25a and a second recess 25b.

The first recess 25a and the second recess 25b are included in the first volume region 24a and the second volume region 24b, respectively.

Preferably, each recess 25a, 25b passes through the frame 21 from side to side along a direction perpendicular to the plane of the frame 21.

In the example shown in Fig. 4, each recess 25a, 25b may include a flat bottom parallel to the outer surface of the frame 21 to which it is directed.

A set of pins 50 project from the bottoms of the respective recesses 25a, 25b.

Thus, by placing the pin (50) on the bottom of at least one recess, the exchange area can be increased and the exchange area can be positioned as close as possible to the bar (30).

Applicants have observed that the greatest temperature rise in the bar 30 occurs when the inductance circuit 10 is in operation. For example, FIG. 6A shows the temperature distribution of the core 1 of the inductance circuit known in the prior art during operation without any heat dissipation means. Table 1 contains the general characteristics of the considered core.

material Ni _1-x Zn _x Fe ₂ O ₄  Total width 46.5 mm  Core thickness 10.8 mm  Total height 29 mm  Center bar diameter 10.8 mm  air gap 4.4 mm  Core volume 9.8 cm ³ Number N of turns Number of turns (N) 19  power 800 W  Coil current 5A  Switching frequency 3 MHz

Thus, while the core 1 comprises a high temperature zone B which reaches a temperature of 250 ° C (in the bar 3), it can be seen in the side zones C1 and C2 of the core 1 It can be seen that the temperature is lower than 170 占 폚.

Also, unlike the prior art, and more particularly the solution according to US 6,920,039 B2, the configuration of the pin 50 according to the present invention does not require a large increase in volume.

Preferably, the fins 50 may be perpendicular to the bottom plane in which they are supported.

Also, preferably, the pin 50 may be completely contained within a volume defined by at least one recess. In the example of Fig. 4, the addition of the heat dissipating means does not lead to an increase in the volume of the core 20. [

Therefore, the entire volume of the core 20 is not affected.

Alternatively, the pin 50 may extend beyond the volume defined by the at least one recess.

The longest pin therefore increases the exchange surface area of the core 20 with the external environment and consequently makes the cooling of the inductive device 1 more efficient when the inductive device 1 is in operation .

According to one particularly preferred embodiment, the first recess 25a and the second recess 25b are tapered outwardly from the bottom of each recess toward the outer side facing the recess. Thus, as illustrated in Figure 6b, better ventilation is provided at the fin (50). Each of the recesses 25a and 25b has a plane parallel to the plane of the frame 21 with a predetermined dimension along a direction perpendicular to the plane of the singer frame 21. The cross section may be a trapezoid, more specifically an isosceles trapezoid.

The pin 50 may be parallel to the plane defined by the frame 21 and may be vertical.

Alternatively, the recess may have a non-limiting V or U-shaped cross-section. The recess may also have a cross section coinciding with the cross section of the volume section, for example the recess may match the shape of the volume section.

A pin 50 extending from the outer side 22 within the volume area of the frame 21, which is located along the extension of the bar 30, thus has a heat radiation area as close as possible to the hot area of the core, Can be generated.

According to a second example, FIG. 6B shows a simulated map of the temperature of the inductance circuit in which the heat sink means is mounted (according to another embodiment of the present invention in which the pin 50 protrudes from the volume V of the core) . At this time, a temperature of 110 DEG C is observed both in the bars C1 and C2 and in the frame (zone B). The temperature is much lower and is even more homogeneous in the core.

The formation of the fin 50 in the core 20 according to the present invention is then performed only to optimize its efficiency in terms of heat dissipation while having an appropriate effect on the inductance of the inductance circuit.

Preferably, the fins 50 are arranged so as to have only a modest effect on the inductance of the inductance circuit 10. Preferably, the difference between the inductance (L _M ) of the inductance circuit (10) and the nominal inductance (L) is less than 5%, preferably less than 2%.

The following protocol can be employed to minimize the difference between the inductance of the inductance circuit 10 according to the present invention and the inductance of the same inductance circuit without heat dissipation means.

In the first step, the inductance circuit is considered without any dissipation means and is characterized by the geometrical parameters of the core (A, I), and the winding in the coil (N).

Then, the map of the magnetic flux lines in the core is precisely calculated using, for example, a finite element calculation program in consideration of the geometric reference shape determined in the first step. Two-dimensional or three-dimensional finite element digital simulations are well known to experts in the subject, and are not specifically described in the present description. The area in the core where local magnetic induction is less than 5% of the average value of the magnetic induction in the core is identified as black in Fig.

In the example illustrated in Figure 5, the first part of the core volume is advantageously identified in a region where the magnetic induction is maintained at less than 5% of the mean value of the magnetic induction in the core, and at least one end of the bar It is located along the extension.

The method provides a specific identification of the region within the core volume in which the fin 50 can be made in the core, while making appropriate modifications to the inductance of the inductance circuit being considered.

Particularly preferably, the pin 50 is parallel to a magnetic flux line that can be generated when the inductance circuit 10 is in operation. Therefore, the difference between the inductance of the circuit and the nominal inductance may be small.

Also, the developed surface of each fin may be 10% to 100%, for example 30%, of the area A.

The depth of the fin 50 may be 10 to 50%, for example 30% of the square root of the area A.

In the case of the bar 30 having a cylindrical shape and having a diameter of 6 mm,

The width of the fin 50 may be 0.1 to 2 mm, for example 1 mm,

The spacing of the fins 50 may be between 0.1 and 0.5 mm, for example 0.2 mm,

The shape of the fin 50 may be rectangular, triangular, or curved.

In a particularly preferred manner, the space between the fins 50 during step c1) may be filled with a non-magnetic material which is a good thermal conductor such as copper or aluminum. Therefore, according to this embodiment, it is possible to form a thermal bridge in order to cool the core 20 efficiently.

Additional fins 51 may be added on the outer surface 22 of the frame 21, as opposed to being added on a hollow surface to further improve the exchange surface area of the core.

Particularly advantageously, the additional fin 51 is made of the same magnetic material as the core 20.

The core 20 may comprise voids thinner than 5% of the effective magnetic length l.

Advantageously, said voids are located in the center of said bar (30).

As mentioned above, the core 20 may be formed by powder injection molding of ferrite. Experts in this topic can find detailed information on powder injection molding method in patent FR2970194 [3]. Such techniques may be applied to a wide range of applications, including organic materials (e.g., polyolefins such as polyethylene, polypropylene) and inorganic powders (e.g., ferrite-type oxides such as Mn _{1 - x} Zn _x Fe ₂ O ₄ and Ni _{1 - x} Zn _x Fe ₂ O ₄ ) to form a master mixture.

The master mixture is then injected into the mold to shape the desired shape on the mold. The molded part is then debanded at a temperature of 400 to 700 占 폚 (e.g., 500 占 폚) to remove the organic matter. The debinding step is followed by a sintering step carried out at a temperature of 900 to 1300 ° C (for example, 1220 ° C for Mn _{1 - x} Zn _x Fe ₂ O ₄ ferrite oxides) so that the density of the resultant formed part increases . At this time, the core may be made of a single piece or an assembly of several parts (for example, two E-shaped pieces or E-shaped and I-shaped or U-shaped and I-shaped assemblies) . Depending on how the core is made, one or more molds may be required.

The space between the fins 50 is filled during step c1) by a conductor material which is well known to the expert in the field and which uses an insert molding technique as described in the literature Ruh et al. [4].

7, the bar 30 can have a square cross-section and the cavities 41a and 41b are adjacent to the two sides 31 and 32 of the core, respectively, To the other side along a direction perpendicular to the longitudinal direction. The cavities 41a and 41b may then be formed using a conductive material (e.g., copper or aluminum) (e.g., by insert molding) to form a portion of the coil 40 to be embedded in the bar 30. [ ). The coil 40 is then completed, for example, by attaching a metal pad 42 on each of the faces of the bar 30 parallel to the plane of the frame 21. Each of the pads 42 forms a continuous coil configured to connect the cavity 41a to the cavity 41b to generate magnetic induction within the bar 30. [

Thus, the windings of the coil partially pass through the volume of the bar. Since the coil is the position of the energy dissipation (by the Joule effect), partial embedding of the windings in the bar also improves dissipation of the heat emitted by the coil through the pin 50 according to the present invention .

 Therefore, the heat dissipating means according to the present invention can efficiently dissipate the heat generated in the inductance circuit. At this time, the operating temperature of the inductance circuit is reduced and becomes much more uniform at different points in the core.

With the use of the heat dissipating means according to the invention, the total volume of the induction circuit is not only moderately or completely reduced.

Unlike the means known in the state of the art, the heat sink is located within the volume of the core. In other words, unlike the highest level of technology, the heat dissipating means should only add a small amount of material or not at all.

More specifically, the heat dissipating means is disposed in the region of the lower core compared to the rest of the volume of the core of the induction circuit in which the magnetic inductance is in operation.

The heat dissipating means according to the invention also make it possible to use the inductance circuit at higher frequencies, preferably above 1 MHz.

references

[1] US 6,920,039 B2.

[2] A. M. LEARY, "Soft Magnetic Materials in High-Frequency, High-Power Conversion Applications", JOM, Volume 64, Issue 7, July 2012, Pages 772-781.

[3] FR2970194.

[4] Take the Ruh et al. , &Quot; The development of two-component micro powder injection by molding and sinter joining ", Microsyst. Technol., 2011, 17: 1547-1556.

Claims (17)

As an inductance circuit,
Wherein the inductance circuit comprises:
a) a frame (21) and a bar (30) located at the center of the frame (21), which is symmetrical with respect to the bar (30) and which is adjacent to the symmetry plane of the bar (30) (30) located at the center of the frame (21), forming two rectangular magnetic loops having a first area (I), wherein the straight portions of the frame (21) have a cross section with an area (A) A core (20) made of a single-piece magnetic material having a total volume (V) including a cross-section (2A) which is twice the cross-section (A);
b) a coil (40) comprising a winding (N) designed to produce magnetic induction in the bar (30);
c) a pin (50) designed to be exposed to an external environment and to dissipate heat, the pin (50) being made of the same magnetic material as the core;
The inductance circuit comprising:
The inductance circuit is characterized in that the pin (50) is at least partially within at least one volume zone (24a, 24b) of the frame (21) and is located along an extension of at least one end of the bar Wherein the inductance circuit comprises: The method according to claim 1,
The pin (50) is located at the bottom of at least one recess (25a, 25b) formed in at least one volume section (24a, 24b) of the frame, the at least one recess (25a, 25b Is directed toward the outer surface (22) of the frame (21) and passes through the frame (21) from one side to the other along a direction perpendicular to the plane of the frame (21). 3. The method of claim 2,
Wherein the at least one recess (24a, 24b) tapers outwardly from its bottom to the outer surface (22) of the frame (21). The method of claim 3,
The at least one recess (25a, 25b) has a cross-section parallel to the plane of the frame (21) having a certain dimension along a direction perpendicular to the plane of the frame (21) Wherein the inductance circuit is a trapezoidal, more preferably an isosceles trapezoidal. 5. The method according to any one of claims 1 to 4,
The pin 50 is made such that the relative difference between the inductance and the nominal inductance L of the inductance circuit 10 is less than 5%, preferably less than 2%. 6. The method according to one of claims 1 to 5,
Wherein the at least one volume zone (24a, 24b) is a zone where the local magnetic inductance is less than 5% of the average value of the magnetic inductance in the core (20) when the inductance circuit is in operation. 7. The method according to any one of claims 1 to 6,
Wherein the pin (50) is parallel to the plane defined by the frame (21). 8. The method according to any one of claims 1 to 7,
Wherein the area developed by each fin is 10% to 100% of the area (A). 9. The method according to any one of claims 1 to 8,
Wherein a pin located in said at least one volume zone (24a, 24b) does not change the volume occupied by said frame (21). 10. The method according to any one of claims 1 to 9,
Wherein an additional pin (51) is added on the outer surface (22) of the frame (21). 11. The method according to any one of claims 1 to 10,
The cross-section of the bar 30 is square and the cavity passes sideways to laterally along a direction perpendicular to the plane of the frame 21 and the cavity is filled with an electrical conductor to form a portion of the coil 40 Inductance circuit formed. 12. The method according to any one of claims 1 to 11,
Wherein the space between the fins (50) is filled with a metallic material selected from a metal material, preferably aluminum and copper. A power converter comprising an inductance circuit (10) according to one of the claims 1 to 12. 13. A method of manufacturing an inductance circuit according to any one of claims 1 to 12,
A method of manufacturing an inductance circuit,
a) generating a theoretical map of magnetic flux lines in the core (20) of the inductance circuit (10) in operation, the inductance circuit (10) having a predetermined inductance value (L) Piece magnetic material having a total volume V which is comprised of a frame 21 and a bar 30 located at the center of the frame 21, (30) located at the center of the frame (21) which is symmetrical with respect to the axis of the bar (30) and which is adjacent to the symmetry plane of the bar (30) and which forms two rectangular magnetic loops Wherein the linear portions of the frame (21) have a cross-section with an area (A) and the bar (30) has a cross-section (2A) which is twice the cross-section (A);
b) using a pre-written map to identify a zone within the core (20) volume of the inductance circuit (10) during operation wherein the magnetic inductance is less than 5% of the average value of the magnetic inductance in the core (20);
c) manufacturing the core (20) considered in step a), wherein the fin (50) is at least partly contained in at least part of a zone of the volume identified in step b), the pin And is positioned along an extension of at least one end of the bar (30), the pin (50) being made of the same magnetic material as the core (20);
d) forming a coil (40) of a conductor material around a portion of the core (20);
Wherein the inductance circuit comprises: 15. The method of claim 14,
Wherein the additional pins are added on an outer surface of the frame. 16. The method according to claim 14 or 15,
Step c1) is performed after step c) to fill the space between the fins (50) with a metallic material. 17. The method according to any one of claims 14 to 16,
Wherein step (c) of manufacturing the core (20) is performed by powder injection molding.

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