FR3089676A1 - ELECTROMAGNETIC INDUCTION DEVICE - Google Patents

Abstract

The invention relates to an electromagnetic induction device (100) comprising: - a core (200) comprising a main leg (210) extending between two ends, and a secondary section (220) connecting the two ends (211, 212 ) of the main leg (210); - two windings, primary (300) and secondary (400), wound on separate portions of the main leg (210), the primary winding (300) being capable of producing a magnetic flux, said inductive flux, intended to pass through the secondary winding (400), - the core (200) further comprises sampling means, forming at least one tongue (230) which extends from the secondary section (220) and is interposed between the main winding and the secondary winding (400), the sampling means taking a part of the magnetic flux, known as the sampled flux, so that said sampled flux is subtracted from the inductive flux passing through the second coil, and loops back into the first winding. Figure for the abstract: Figure 4A.

Description

Description

Title of the invention: ELECTROMAGNETIC INDUCTION DEVICE

Technical area

The present invention relates to an electromagnetic induction device.

More particularly, the present invention relates to an electromagnetic induction device which comprises sampling means giving a primary winding the behavior of two inductors in series.

The electromagnetic induction device according to the present invention is advantageously implemented in a power transformer, in particular a power transformer in the automotive field, and more particularly for charging electric motor vehicles.

Prior art

In recent years, there has been a significant boom in electric vehicles.

These implement a battery which delivers the power necessary for the traction of the vehicle, and the charge of which is carried out during the phase of the vehicle in question.

This charge, carried out at charging terminals which deliver alternating current, requires the use of an AC-DC converter.

However, given the volume that they are likely to occupy in the charging stations, manufacturers are considering integrating them into motor vehicles.

This solution allows to consider interfacing the AC-DC converter with the on-board electronics of the motor vehicle.

More particularly, an exchange of information, by suitable means of communication, can be implemented between the AC-DC converter and the various components of the vehicle and in particular the battery management system.

The AC-DC converter can benefit from connectivity with the outside to provide various services such as "smart charging", geographic positioning to adapt the "grid code", ...

It is therefore preferable that the AC-DC converters meet specific constraints and in particular have a reduced volume, for example by implementing a magnetic core operating at relatively high frequency.

It is also envisaged to make the AC-DC converters bidirectional and thus pave the way for storage of and / or distribution of energy by the battery or batteries of electric vehicles.

Such an arrangement would then overcome, in part, the shortcomings of the electrical network to which said vehicles are connected during phases of overproduction of energy and / or consumption peaks.

A bidirectional AC-DC converter, however, requires a special arrangement to make it quieter.

Finally, the proposed arrangement must also address a performance issue so as to limit the electrical losses during the conversion of the current.

For these purposes, at least two topologies of converters (described in the document [1] cited at the end of the description) said, respectively, of LLC type (resonant converter illustrated in FIG. 1) and of DAB type ( for "Dual Active Bridge", illustrated in figure 2) could be proposed.

The LLC topology is notably based on the integration of a resonant type stage (“resonant tank” according to English terminology), and includes a transformer associated with capacitors, of capacity 2C and inductances mounted in "Series".

The inductors and the capacitors are adjusted to operate in resonance at a frequency close to the nominal switching frequency of the switches.

The transformer is also arranged to allow galvanic isolation of the input and load circuits, and the adaptation of the voltage value applied to the terminals of the load.

It includes in particular a primary winding and a secondary winding formed around a magnetic core, with a ratio of number of turns n equal to the ratio of the input and load voltages.

In a balanced LLC configuration, the resonant serial components are duplicated on both sides of the same winding. The magnetizing inductance of the transformer Lm, which is a function of the number of turns of the primary winding and the geometry of the core, is, in the case of the LLC topology, determined precisely to ensure the gain adjustment of the converter.

The DAB topology includes arms placed on either side of the transformer devoid of capacity. The inductors in series have the function of transmitting the power.

The magnetizing inductance of the transformer is no longer constrained to a value given in DAB topology, and must only be high enough to obtain a good rate of use. However, in this bidirectional topology, it is preferable to implement 4 inductors connected in series with the transformer so as to have the most symmetrical circuit possible and thus limit the common mode disturbances at very low level which reduce the size. input filtering.

The inductors, typically of the order of 1 to 10 μΗ, and connected in series with the transformer in the LLC and DAB topologies, are, in the prior art, components of the discrete type, placed at the outside the transformer.

These components generally occupy a large volume which one seeks to reduce by integrating them into the heart of the transformer.

The document [2] cited at the end of the description proposes to take advantage of the natural leakage inductance of the transformer as a series inductor as illustrated in FIG. 3.

The leakage inductance characterizes, in particular, the part of the magnetic flux created by the primary winding of the transformer and which does not cross the secondary winding.

This leakage inductance is representative of non-ideal operation of the transformer, and is the source of a distribution of part of the magnetic flux around the component considered.

The leakage inductance is generally low (less than 1 microHenry, μΗ), and their evaluation is difficult to predict.

Also, in order to increase the value of the leakage inductance, it is proposed in document [3] to provide a space between the first winding and the second winding.

However, this arrangement only allows the creation of a single series inductor in the transformer, and therefore cannot be implemented in balanced LLC or DAB configurations.

Furthermore, the spacing created between the first winding and the second winding tends to increase the volume of the transformer.

In addition, the magnetic leaks around the winding constrain its implantation by prohibiting the presence of any conductive element nearby so as not to induce eddy currents there, which significantly increases the volume of the converter.

The document [3] cited at the end of the description proposes to introduce an additional winding around the core, as illustrated in FIG. 3.

In particular, the additional winding is intended to create in the core an integrated inductance thanks to the circulation of a magnetic flux in a direction identical or different to that of the main flux.

The increase in the volume of the core remains limited as long as a single additional winding is considered.

However, this configuration offers little flexibility as to the adjustment of the magnetic circuit, in terms of length and section, to achieve the series inductance.

An object of the present invention is therefore to provide a transformer provided with a controlled leakage inductance and which does not induce a significant increase in volume. Statement of the invention

The object of the present invention is achieved by an electroma4 magnetic induction device comprising:

- a core comprising a main leg extending between two ends, and a secondary section connecting the two ends of the main leg;

two windings, primary and secondary, wound on separate portions of the main leg, the primary winding being capable of producing a magnetic flux, called inductive flux, intended to pass through the secondary winding,

the core also comprises sampling means, forming at least one tongue which extends from the secondary section and is interposed between the main winding and the secondary winding, the sampling means taking part of the magnetic flux, said withdrawn flow, so that said withdrawn flow is subtracted from the inductive flow passing through the second winding, and loops back into the first winding.

According to one embodiment, the tongue is at a distance from the main leg so that the flow taken is limited to part of the inductive flow flowing out of the main leg.

According to one embodiment, the secondary section comprises a side leg essentially parallel to the main leg.

According to one embodiment, the lateral leg comprises an internal surface facing a peripheral surface of the main leg, advantageously the internal surface at least partially circumvents the peripheral surface, even more advantageously, the internal surface at least partially conforms to the peripheral surface.

According to one embodiment, the at least one tongue forms a flange which also extends along the internal surface in a direction perpendicular to a direction defined by the ends of the main leg.

According to one embodiment, the secondary section comprises two plates essentially parallel to each other, and now secured to one another the main leg and the side leg.

According to one embodiment, the main leg is of cylindrical shape.

According to one embodiment, the primary winding comprises two primary sub windings, electrically connected in series, and arranged on either side of the secondary winding.

According to one mode of implementation, the two primary windings each include an identical number of turns of metallic conductor.

According to one embodiment, the at least one tab comprises a first tab and a second tab each interposed between the secondary winding and a different sub-winding.

The invention also relates to a transformer provided with the electromagnetic induction device according to the present invention.

According to one embodiment, the first winding and the second winding are each connected in series with a capacity, called respectively first capacity and second capacity.

According to one embodiment, said transformer further comprises a first AC-AC converter connected in parallel with a branch formed by the first winding and the first capacitance, and a second AC-DC converter connected in parallel with a another branch formed by the second winding and the second capacitance.

Brief description of the drawings

Other characteristics and advantages will appear in the following description of an electromagnetic induction device according to the invention, given by way of nonlimiting examples, with reference to the appended drawings in which:

[Fig.l] is a schematic representation in discrete components of a transformer in LLC topology known from the state of the art;

[Fig.2] is a schematic representation in discrete components of a transformer in DAB topology known from the state of the art;

[Fig.3] is a schematic representation of a primary winding and a concentric secondary winding formed around a section of a core known from the prior art;

[Fig.4A] is a schematic representation of an electromagnetic induction device provided with a single sampling means according to the present invention, the core is in particular shown with the primary winding and the secondary winding according to a plane of cross section;

[Fig.4B] is a schematic representation of an electromagnetic induction device provided with two sampling means according to the present invention, the core is in particular shown with the primary winding and the secondary winding according to a transverse cutting plane ;

[Fig.5A] is a representation of an equivalent electrical diagram of the device shown in Figure 4a;

[Fig.5B] is a representation of an equivalent electrical diagram of the device shown in Figure 4b;

[Fig.6A]

[Fig.6B] are schematic representations of the device according to cutting plane and in perspective, Figures 6a and 6b show in particular the device, respectively, without its windings and with its windings;

[Fig.7] uses Figure 6a and illustrates the geometric details of a tongue capable of being implemented in the context of the present invention;

[Fig. 8 A]

[Fig.8B] are schematic representations of the core illustrating the geometric characteristics of said core in relation to Table 2;

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

The present invention relates to an electromagnetic induction device provided with a primary winding and a secondary winding wound on two different sections of the same main leg of a ferromagnetic core.

The ferromagnetic core further comprises a secondary section connecting the two ends of the main leg.

The device according to the present invention implements an inductor, called a leakage inductor, formed from a section of the primary winding.

The leakage inductance is notably formed via sampling means which include a tongue extending from the secondary section, and interposed between the primary winding and the secondary winding.

In Figure 4a, we can see an electromagnetic induction device 100 according to the present invention.

The device 100 includes in particular a core 200, and more particularly a core made of a ferromagnetic material.

The ferromagnetic material can be sintered and in particular comprise at least one of the materials chosen from: MnZn, NiZn.

The core 200 includes a main leg 210 and a secondary section 220.

By "leg" means a section which has an elongated shape. The leg can then take the form of a bar, in particular a bar of cylindrical cross section.

The main leg 210 extends longitudinally between its two ends 211 and 212.

The secondary section 220 connects the two ends 211 and 212 of the main leg so as to form a magnetic loop.

By "magnetic loop" means a path followed by a magnetic flux capable of flowing in the core. It is understood that a magnetic loop is closed.

The device according to the present invention also comprises a primary winding 300 and a secondary winding 400.

A coil, according to the present invention, comprises a number N of turns of a conductive material wound around a body.

The primary winding 300 and the secondary winding 400 are wound on separate portions of the main leg 210.

Furthermore, the primary winding 300 is capable, in particular when it is traversed by an electric current, of producing a magnetic flux, called inductive flux, intended to pass through the secondary winding 400 (loop "M" in FIGS. 4a and 4b).

In addition, the primary winding 300 can be wound around the main leg 210 so that an annular space 310 is interposed between the primary winding 300 and the main leg 210.

It is understood that the annular space 310 extends over the length of the primary winding 300 and is delimited laterally by an internal surface of the primary winding 300 and the surface of the main leg 210.

The length of a coil corresponds to its dimension according to the direction of elongation of the leg around which it is wound.

The secondary section 220 may include a side leg 240 essentially parallel to the main leg 210.

The side leg 240 includes an internal surface 241 opposite a peripheral surface 213 of the main leg 210.

In a particularly advantageous manner, the internal surface 241 at least partially circumvents the peripheral surface 213 (FIGS. 6a and 6b).

Still advantageously, the internal surface 241 at least partially conforms by circumference to the peripheral surface 213.

By "bypass conformally" means two surfaces, one of which is the image of the other by homothety.

The secondary section 220 may also include two plates 250, 251 essentially parallel to each other, and now secured to one another the main leg 210 and the side leg 240.

The main leg 210 may be of cylindrical shape.

According to the present invention, the core 100 also comprises sampling means, forming at least one tongue 230 which extends from the lateral leg 230, and is interposed between the primary winding 300 and the secondary winding 400 .

It is understood, without it being necessary to specify it, as soon as the tongue is interposed between the primary winding and the secondary winding, the latter is exposed to the inductive flux likely to be produced by the primary winding .

By "tongue" is meant a relief, in particular a profile which extends from the surface of the secondary section. The profile, according to the present invention, can however take any type of shape.

In this regard, as illustrated in Figure 7, tongue 230 may include two faces 231 and 232 essentially parallel to each other, and perpendicular to the main leg 210. The two faces 231 and 232 are connected by a contour 233 .

The distance between the two faces 231 and 232 defines the thickness E of the tongue.

The contour 233 comprises two lateral sections 233a and 233b, which extend from the internal surface, and which are connected by a section, called the end section 233t, facing the peripheral surface 213.

Advantageously, the end section 233t is spaced from the peripheral surface 213. In other words, the tongue 230 is not in contact with the main leg 210.

Still advantageously, the terminal section 233t conforms to the peripheral surface.

As soon as it is interposed between the primary winding 300 and the secondary winding 400, the tongue deflects part of the inductive flow, called the withdrawn flow (loop "P" in FIGS. 4a and 4b), so that the latter does not pass through the secondary winding.

As soon as the tongue 230 is at a distance from the main leg 210, the flow taken is limited to a part of the inductive flow flowing out of the main leg, and in particular limited to the inductive flow flowing in the annular space 310.

The sampled flux, in the same way as the inductor flux, form a magnetic loop P. However, this loop P flows successively in the tongue, the secondary section then in the primary winding (FIGS. 4a and 4b).

In other words, the implementation of the sampling means makes it possible to transform the inductance formed by the primary winding 300 into two inductors in series. More particularly, under the effect of the sampling means, the primary winding 300 reproduces the behavior of two inductors in series, called, respectively, leakage inductance Lr and magnetizing inductance Lm.

In this regard, the magnetizing inductance determines, with in particular the number of turns of the secondary winding, the transformation ratio (or the gain) between the input voltage at the primary winding and the output voltage at the level secondary winding. The leakage inductance allows it to store electromagnetic energy and to restore it when the time comes.

The equivalent electrical diagram relating to the device of Figure 4a is shown in Figure 5a. The latter notably includes the magnetizing inductor Lm in series with the leakage inductor Lr.

This arrangement is particularly advantageous, since it allows, without significant increase in volume of the device, to create, from the primary winding, a leakage inductance in series with a magnetizing inductance.

The leakage inductance is a function of the geometric characteristics of the tongue.

FIG. 4b represents an advantageous variant of the electromagnetic induction device which essentially takes up all the characteristics of the device described in relation to FIG. 4a.

According to this variant, the primary winding 300 comprises two primary sub windings 300a and 300b, electrically connected in series, and arranged on either side of the secondary winding 400.

In a particularly advantageous manner, the two primary windings 300a and 300b each comprise an identical number of turns of metallic conductor.

Still according to this variant, the electromagnetic induction device is provided with two tabs 230 said, respectively, first tab 230a and second tab 230b.

The first tab and the second tab each interpose between the secondary winding 400 and a different primary sub-winding.

The implementation of the two tongues 230a and 230b makes it possible to take a part of the inductive flux generated by each of the two sub primary coils.

Furthermore, the device can be symmetrical with respect to a plane of symmetry perpendicular to the main leg. According to this configuration, the sampling of the flow is also symmetrical, and, in fact, makes it possible to limit the common mode disturbances. The equivalent electrical diagram relating to the device of Figure 4b is shown in Figure 5b. The latter notably includes the magnetizing inductor Lm in series with two Lr / 2 leakage inductors.

Furthermore, whatever the variant considered, the core can correspond to an arrangement of two parts, in particular two identical parts in the context of the second variant.

The following section presents an example of dimensioning of the device described in relation to FIG. 5a.

In particular, Table 1 brings together the specifications of a transformer of the “LLC” type having a resonant frequency of 500 kHz, and comprising the electromagnetic induction device according to the present invention.

[Table 1]

Physical size Target value Unit Input voltage 450 V Output voltage at nominal power: 300-430 V Nominal power 11 kW Transformation ratio 4: 3 leakage series inductor U 3 + / 5% μΗ .magnetizing inductance 18 +/- 5% μΗ Frequency range at nominal power 325-625 kHz

Table 2 brings together the characteristics of the electromagnetic induction device making it possible to comply with the specifications gathered in Table 1 (the ratings "A", "B", "Di", "D ₂ ", "E", " F "and" H "are shown in Figures 8a and 8b).

[Table 2]

Core width (mm) A 50 Depth (mm) 8 22.38 Main leg diameter (mm) Di 28.63 Outer diameter of flange (mm) D2 34.88 Height of the half-core (mm) E 12.29 Inner pillar length (mm) F 3.5 Tongue thickness (mm) H .3.

The design of the core according to the present invention may use an injection molding technique ("PIM" or "Powder Injection Molding" according to Anglo-Saxon terminology). This technique is particularly well suited for the production of parts in large series.

Injection molding first implements a step of forming a masterbatch ("feedstock" according to Anglo-Saxon terminology).

The masterbatch comprises in particular a mixture of organic material (or polymeric binder) and inorganic powders (metallic or ceramic) intended to form the final part.

The masterbatch is injected into an injection molding machine, the technology of which is known to a person skilled in the art. The injection press makes it possible to melt the polymers injected with the powder in a cavity, and to give said powder the desired shape.

The masterbatch, thus melted, is subjected to cooling so as to freeze it in a form imposed by the injection molding machine.

The part formed by the masterbatch is then removed from the mold, and unbound in order to remove the organic matter.

The part can then be consolidated by sintering.

The invention also relates to a transformer (in particular a transformer of the "LLC" type) provided with the electromagnetic induction device according to the present invention.

In particular, the first winding 300 and the second winding 400 are each connected in series with a capacitance, called first capacitance and second capacitance respectively.

The transformer further comprises a first AC-AC converter connected in parallel with a branch formed by the first winding and the first capacitance, and a second AC-DC converter connected in parallel with another branch formed by the second winding and the second capacitance.

List of documents cited

[1] Inoué, “A Bidirectional DC-DC Converter for an Energy Storage System With

Galvanic Isolation ”, IEEE Transactions on Power Electronics, Vol .: 22, No .: 6,2007,

[2] Mingkai Mu et al., “Design of Integrated Transformer and Inductor for High

Erequency Dual Active Bridge GaN Charger for PHEV ", IEEE Applied Power Electronics Conference and Exposition, pages 579-585, 15-19 March 2015,

US 6,320,490.

Claims (1)

Claims [Claim 1] Electromagnetic induction device (100) comprising: - a core (200) comprising a main leg (210) extending between two ends, and a secondary section (220) connecting the two ends (211, 212) of the main leg (210); - two windings, primary (300) and secondary (400), wound on separate portions of the main leg (210), the primary winding (300) being capable of producing a magnetic flux, called inductive flux, intended to pass through the winding secondary (400), - The core (200) further comprises sampling means, forming at least one tongue (230) which extends from the secondary section (220) and is interposed between the main winding and the secondary winding (400) , the sampling means taking a part of the magnetic flux, called the sampled flux, so that said sampled flux is subtracted from the inductive flux passing through the second coil, and loops back into the first coil. [Claim 2] Device according to claim 1, in which the tongue (230) is at a distance from the main leg (210) so that the flow taken is limited to a part of the inductive flow flowing out of the main leg (210). [Claim 3] The device of claim 1 or 2, wherein the secondary section (220) includes a side leg (240) substantially parallel to the main leg (210). [Claim 4] Device according to claim 3, in which the lateral leg (240) comprises an internal surface (241) facing a peripheral surface (213) of the main leg (210), the internal surface (241) at least partially bypassing the peripheral surface (213), advantageously, the internal surface (241) at least partially conforms by circumference to the peripheral surface (213). [Claim 5] Device according to claim 4, in which the at least one tongue (230) forms a flange which also extends along the internal surface (241) in a direction perpendicular to a direction defined by the ends of the main leg ( 210). [Claim 6] Device according to one of claims 3 to 5, in which the secondary section (220) comprises two plates (250, 251) essentially parallel to each other, and now integral with one another the main leg (210) and the side leg (240). [Claim 7] Device according to one of claims 1 to 6, in which the main leg (210) is of cylindrical shape. [Claim 8] Device according to one of claims 1 to 7, in which the primary winding (300) comprises two primary sub windings (300a, 300b), electrically connected in series, and arranged on either side of the secondary winding (400). [Claim 9] Device according to claim 8, in which the two primary windings (300) each comprise an identical number of turns of metallic conductor. [Claim 10] Device according to claim 8 or 9, in which the at least one tab (230) comprises a first tab (230a) and a second tab (230b) each interposed between the secondary winding (400) and a different primary sub-winding . [Claim 11] Transformer provided with the device according to one of claims 1 to 1 Π [Claim 12] IV. A transformer according to claim 11, in which the first winding and the second winding are each connected in series with a capacity, called first capacity and second capacity respectively. [Claim 13] The transformer of claim 12, wherein said transformer further comprises a first AC-AC converter connected in parallel with a branch formed by the first winding and the first capacitor, and a second AC-DC converter connected in parallel with another formed branch by the second winding and the second capacity. 1/6