JP7378475B2 - electromagnetic induction device - Google Patents

Description

The present invention relates to an electromagnetic induction device.

More particularly, the present invention relates to an electromagnetic induction device comprising pickup means for imparting to a primary coil the behavior of two inductances connected in series.

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

Electric vehicles have come a long way over the past few years.

Such electric vehicles are equipped with a battery that supplies the power necessary to drive the vehicle, and the battery is charged while the vehicle is still in operation.

This charging, which takes place at the charging terminal level where alternating current is supplied, requires the use of an AC-DC converter.

However, given the volume that AC-DC converters are likely to occupy at charging terminals, manufacturers are tempted to incorporate them into motor vehicles.

This solution makes it possible to plan an interface between the AC-DC converter and the on-board electronics of a motor vehicle.

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

AC-DC converters can benefit from external connectivity for various services such as 'smart charging' and positioning for 'grid code' compliance.

It is therefore preferable for the AC-DC converter to be adapted to the individual constraints, for example by implementing a magnetic core operating at a relatively high frequency, and in particular to be compact.

It is also planned to bidirectionalize AC-DC converters, thereby paving the way for energy storage and/or distribution by batteries in electric vehicles.

Such an arrangement would make it possible to partially address the inadequacies of the electrical system to which the vehicle in question is connected during periods of overproduction and/or peak consumption of energy.

However, bidirectional AC-DC converters require special arrangements that can make the converter quieter.

And finally, the proposed arrangement must also address efficiency issues in a way that reduces power losses during current conversion.

Therefore, converters with at least two topologies (listed in document [1] shown at the end of this specification) are used, respectively: LLC type (resonant converter shown in FIG. 1) and DAB type ("Dual Active Bridge"). 2) was proposed.

The LLC topology specifically incorporates a resonant type stage ('resonant tank' in Anglo-American technical terminology) and a transformer that combines a capacitor and inductance with a capacitance of 2C connected in 'series'.

The inductance and capacitor are tuned to operate resonantly at a frequency close to the nominal switching frequency of the switch.

The transformer is also arranged in such a way as to allow galvanic isolation of the input and load circuits and adaptation of the value of the voltage applied to the terminals of the load.

The transformer comprises, inter alia, a primary coil and a secondary coil formed around a magnetic core with a ratio n of turns equal to the ratio of input voltage to load voltage.

In a balanced LLC configuration, the series resonant elements are duplicated on opposite sides of the same winding. For the LLC topology, the magnetizing inductance of the transformer Lm, which is a function of the number of turns of the primary coil and the geometry of the core, is precisely defined and the gain of the converter is adjusted.

On the other hand, the DAB topology comprises zero capacitance branches placed on both sides of the transformer. The series inductance serves to transfer power.

In the DAB topology, the magnetizing inductance of the transformer is not bound to a given value, but only needs to be high enough to obtain good utilization. However, in this bidirectional topology, the four inductances connected in series with the transformer are implemented in a way that makes the circuit as symmetrical as possible, thereby minimizing the filtering of common mode disturbances on the input side. It is preferable to limit it to a very low level.

The inductance in series with the transformer in LLC and DAB topologies is typically on the order of 1-10 μH and in the prior art is a discrete component placed outside the transformer.

Since these components generally occupy a large volume, the aim is to reduce their volume by incorporating them inside the transformer.

Document [2] listed at the end of this specification proposes to utilize the natural leakage inductance of a transformer as a series inductance, as shown in FIG.

What is characterized as leakage inductance is, in particular, the magnetic flux generated by the primary coil of a transformer that does not pass through the secondary coil.

This leakage inductance is representative of non-ideal operation of the transformer and is responsible for the distribution of a portion of the magnetic flux around the component in question.

Leakage inductance is generally weak (less than 1 microhenry (μH)) and difficult to predict.

Therefore, in order to increase the value of leakage inductance, document [3] proposes providing a space between the first coil and the second coil.

However, this arrangement can only create a single series inductance in the transformer and therefore cannot be implemented in an LLC or DAB balanced configuration.

On the other hand, the spacing between the first coil and the second coil tends to increase the volume of the transformer.

Furthermore, magnetic leakage around the coils restricts the placement of the coils by prohibiting the presence of nearby conductors to avoid inducing Foucault currents, resulting in a considerable increase in the converter's volume.

Document [3] cited at the end of this specification proposes introducing an additional coil around the core, as shown in FIG. 3.

Among other things, this additional coil is intended to create an inductance built into the core by a flow of magnetic flux in the same or a different direction than the main magnetic flux.

The increase in core volume remains limited as long as only one additional coil is considered.

However, this configuration does not provide much flexibility in terms of adjusting the magnetic circuit in terms of length and cross-sectional area in realizing the series inductance.

It is therefore an object of the invention to propose a transformer with controlled leakage inductance, which does not result in a noticeable increase in volume.

The purpose of the present invention is to
- a ferromagnetic core comprising a plurality of piers essentially parallel to each other, each extending between two ends, the plurality of piers comprising at least one main pier, at least one lateral pier and a ferromagnetic core including at least two leaky peers;
- at least one primary coil and at least one secondary coil, each having a main section wrapped around a main pier and each wrapped around a different leaky pier, referred to as a primary leakage section and a secondary leakage section, respectively; an electromagnetic induction device comprising a primary coil and a secondary coil, including a leakage section and a primary coil and a secondary coil.

According to an embodiment, the core has two plates, respectively called a lower plate and an upper plate, each plate facing each other at inner surfaces called a lower inner surface and an upper inner surface, respectively, and a plurality of plates between the two plates. The pier extends.

According to an embodiment, each peer of the plurality of peers has a gap.

According to an embodiment, the gap, referred to as the leakage gap, of each of the at least two leaky peers is greater than or equal to, and preferably strictly exceeds, the gap of the other peer.

According to an embodiment, the gap of at least one main peer and the gap of at least one side peer are the same.

According to an embodiment, a plane equidistant from the two inner surfaces forms a plane of symmetry of the core.

According to an embodiment, a machined groove is formed on both of the inner surfaces at a distance so as to at least partially surround each of the two ends of each leakage pier, and the machined groove is formed on both the leakage pier and the main pier. caught between.

According to an embodiment, each pier of the plurality of peers is cylindrical.

According to an embodiment, the at least one main pier comprises only one main pier, and the at least one side pier comprises four lateral peers regularly arranged around the main pier. .

According to an embodiment, the at least two leaky piers comprise four leaky piers arranged regularly around the main pier, advantageously the whole leaky pier being at an angle of 45° to the side piers. Has an angular offset.

According to an embodiment, the primary leakage section is comprised of two primary leakage sections, such that the primary coil includes in turn one of the primary leakage sections, the main section and the other primary leakage section, the primary leakage section being The sections are each wrapped around different diametrically opposing leakage piers.

According to an embodiment, the secondary leaky section consists of two secondary leaky sections, such that the primary coil includes one of the secondary leaky sections, the main section and the other secondary leaky section in sequence. , whose secondary leakage sections are each wrapped around different diametrically opposed leakage piers.

According to an embodiment, the at least one primary peer consists of three primary peers together with the at least one side peer, each primary peer having its own set of two leaking peers. combined.

According to an embodiment, the three main piers are arranged regularly around a main axis parallel to them.

According to an embodiment, the two leaky peers of a given set of peers are diametrically opposed to the primary pier with which they are associated.

According to an embodiment, the two leaky peers of the set of peers are arranged symmetrically with respect to a plane passing through the principal axis.

The invention also relates to a transformer equipped with a device according to the invention.

Other features and advantages will become apparent from the following description of an electromagnetic induction device according to the invention, given by way of non-limiting example and with reference to the accompanying drawings, in which: FIG.

1 is a schematic diagram of the discrete components of a transformer of LLC topology as known in the state of the art; FIG. 1 is a schematic diagram of the discrete components of a transformer of DAB topology known in the state of the art; FIG. 1 is a schematic diagram of concentric primary and secondary coils formed around a section of a core as known in the state of the art; FIG. 1 is a schematic perspective view of an electromagnetic induction device according to a first variant of the invention; FIG. FIG. 7 is a perspective view of a lower block of the core that is assumed to be mounted in the first modification. FIG. 7 is a perspective view of the upper block of the core that is assumed to be mounted in the first modification. FIG. 3 is a perspective view of a block, particularly a lower block, showing mounting of processing grooves. FIG. 3 is a perspective view of the block, particularly the lower block, showing the arrangement of the main coil and the secondary coil. Figure 2 shows two diagrams of the block showing the geometric characteristics of the block in conjunction with Table 2; FIG. 3 is a schematic diagram of the blocks, in particular the lower block, showing the arrangement of each peer within the framework of the second variant of the invention; 5 is an equivalent circuit diagram of the device shown in FIG. 4. FIG. FIG. 2 is a schematic diagram of the overall arrangement of blocks and coils.

The electromagnetic induction device according to the invention comprises a ferromagnetic core including a main pier and at least two leaky pier.

In particular, the electromagnetic induction device comprises two coils, one wrapped around the main pier and one wrapped around each different leaky pier.

This arrangement may impart to each of the coils the behavior of a series-connected inductance, in particular an excitation inductance in series with at least one inductance, called a leakage inductance.

FIG. 4 is a schematic diagram of the electromagnetic induction device 1000.

The device 1000 comprises a core 2000, more specifically a core made of ferromagnetic material.

The ferromagnetic material can be sintered and can include at least one material chosen in particular from among MnZn, NiZn.

The ferromagnetic core comprises a plurality of piers essentially parallel to each other, each extending between two ends.

The plurality of peers includes at least one primary peer, at least one side peer, and at least two leaky peers.

"Pier" refers to a section that has an elongated shape. That is, the pier can have the shape of a rod, in particular a rod of cylindrical cross section.

Piers can be cylindrical.

The main pier 2100 extends longitudinally between its two ends 2110 and 2120 (FIGS. 5a and 5b).

The core 1000 comprises two plates, called a bottom plate 2500 and a top plate 2510, respectively, which are essentially parallel to each other, each plate facing each other on one side, called a bottom inner surface 2500a and a top inner surface 2510a, respectively. are doing.

Lower plate 2500 and upper plate 2510 are advantageously perpendicular to the piers.

Advantageously, the main pier, the at least one side pier and the at least two leaky peers are gaps, referred to in Anglo-American technical terminology as "air gaps", each of which has a main gap, Gaps may be provided that are qualified as lateral gaps and leakage gaps.

Since a gap exists between each of the plurality of peers, it is possible to consider a core consisting of two mutually symmetrical blocks called a lower block and an upper block, respectively. Each block comprises a plate 2500 or 2510 and a plurality of half-peers.

In the following discussion, each peer is allowed to have one gap, regardless of the variant considered.

According to a first variant shown in FIGS. 5a and 5b, the device comprises only one main pier 2100, such as in a central position relative to the two plates 2500 and 2510.

The at least one side pier consists of four side piers 2201, 2202, 2203 and 2204 arranged regularly around the main pier.

The at least two leaky peers consist of four leaky peers 2301, 2302, 2303 and 2304 regularly arranged around the main peer.

Advantageously, the entire leakage pier has an angular offset of 45° with respect to the side piers.

According to this first variant, the device comprises only one primary coil 3000 and only one secondary coil 4000 (FIG. 7).

The first coil 3000 has one main section 3000a wrapped around a main pier and two primary leaky sections, respectively referred to as a first primary leakage section 3000b and a second primary leakage section 3000c. each comprising a primary leakage section wrapped around two different leakage peers.

In particular, the first primary leakage section 3000b and the second primary leakage section 3000c are wrapped around two diametrically opposed leakage piers.

The second coil 4000 has one secondary section 4000a wrapped around the main pier and two secondary leaky sections, respectively referred to as a first secondary leaky section 4000b and a second secondary leaky section 4000c. and a secondary leakage section, each wrapped around two different leakage peers.

It is needless to point out that a leaky pier with two secondary leaky sections wrapped around it is different from a leaky pier with two primary leaky sections wrapped around it.

In particular, the first secondary leakage section 4000b and the second secondary leakage section 4000c are wrapped around two diametrically opposed leakage piers.

Therefore, all the magnetic flux called field flux generated by either the primary section 3000a or the secondary section 4000a flows through the other section. In other words, the primary section 3000a and the secondary section 4000a perform the primary function of a transformer, namely voltage conversion.

The primary leakage sections 3000b, 3000c and the secondary leakage sections 4000b, 4000c act as leakage inductances.

In this arrangement, each coil exhibits the behavior of three inductances in series, respectively called leakage inductance Lr and magnetizing inductance Lm.

In that case, the magnetizing inductance defines the transformation ratio (ie, the gain) between the voltage at one coil level and the output voltage at another coil level. Leakage inductance, on the other hand, stores electromagnetic energy and releases it when needed. In other words, leakage inductance moves power.

An equivalent circuit diagram of the device of FIG. 4 is shown in FIG. This diagram includes, inter alia, a magnetizing inductance Lm connected in series with two leakage inductances Lr.

In operation, current flows through either coil, such as the first coil.

Due to the action of this current, a magnetic flux called excitation flux generated by the main section also passes through the secondary section 4000a, forming a magnetic loop flowing through the side pier and the leakage pier, thereby forming a magnetic loop in the core 2000.

However, the core may include arrangements to encourage the flow of excitation flux in the side piers 2201 , 2202 , 2203 and 2204 rather than in the leaky piers 2301 , 2302 , 2303 and 2304 .

The leakage gap can then be larger than the side gaps.

As an alternative or complementary method, machined grooves 2301a, 2302a, 2303a and 2304a may be formed on both of the interior surfaces spaced apart to at least partially surround each of the two ends of each leakage pier. The machined groove is sandwiched between the leakage pier and the main pier (Figure 6).

Below, an example of the device design will be introduced in relation to FIG. 4.

Table 1 specifically summarizes the specifications of a "DAB" type transformer with a resonant frequency of 500 kHz and equipped with an electromagnetic induction device according to the invention.

Table 2 summarizes the characteristics of the electromagnetic induction device that can comply with the specifications summarized in Table 1 (the dimensions are as shown in FIG. 8).

The principles described in the first variant are adapted and implemented under the second variant for the implementation of a multi-phase, especially three-phase electromagnetic induction device.

FIG. 9 shows an embodiment of the three-phase induction device.

In this embodiment, each element in the first variant can basically be used again.

In this second variant, the core comprises three main peers 2101, 2102 and 2103 and no side peers.

The three main piers may be arranged regularly around an axis parallel to them called the main axis XX'.

Each primary pier 2101, 2102 and 2103 is also combined with two leaky piers 2305a, 2305b, 2306a, 2306b, 2307a, 2307b, 2308a and 2308b, as well as primary coils 3001, 3002 and 3003 and their corresponding secondary It is combined with coils 4001, 4002, and 4003.

More specifically, the main pier, the two leaky piers, and the primary and secondary coils form one phase of the electromagnetic induction device 1000.

For each phase, the first coils 3001, 3002 and 3003 have main sections 3001a, 3002a and 3003a wrapped around the main pier and primary leaky sections 3001b, 3002b and 3003b wrapped around the leaky pier. (Figure 11).

Similarly, the second coils 4001, 4002 and 4003 have secondary sections 4001a, 4002a and 4003a wrapped around the main pier and secondary leaky sections 4001b, 4002b and 4002b wrapped around the other leaky pier. 4003b (FIG. 11).

It is needless to point out that a leaky pier with a secondary leaky section wrapped around it is different from a leaky pier with a primary leaky section wrapped around it.

Therefore, all the magnetic flux called field flux generated by any one of the primary sections 3001a, 3002a, and 3003a and the secondary sections 4001a, 4002a, and 4003a flows through the other section. In other words, the primary sections 3001a, 3002a and 3003a and the secondary sections 4001a, 4002a, 4003a perform the main function of a transformer, namely converting voltage.

Since there are no side piers, the magnetic flux generated at the main pier level flows through one and/or the other of the other two main piers.

The core design according to the present invention allows for the use of injection molding techniques (in Anglo-American technical terminology "PIM", or "Powder Injection Molding"). This technique is very suitable for mass production of products.

Injection molding begins with the step of forming a masterbatch ("feedstock" in Anglo-American technical terminology).

Masterbatches specifically include a mixture of organic materials (or polymeric binders) and inorganic powders (metals or ceramics) to form the final product.

The masterbatch is injected into an injection molding machine using techniques well known to those skilled in the art. The injection molding machine can melt the injected polymer together with the powder within the cavity and give the powder a desired shape.

The so-molded masterbatch is cooled and solidified into the shape forced by the injection molding machine.

The molded article formed by the masterbatch is taken out from the mold and subjected to a binder removal treatment to remove the organic material.

The part can then be further stabilized by sintering.

The invention also relates to a transformer (in particular a transformer of the "DAB" type) equipped with an electromagnetic induction device according to the invention.

(References)
[1] Inoue, “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 Frequency Dual Active Bridge GaN Charger for PHEV >>, IEEE Applied Power Electronics Conference and Exposition, pages 579-585, 15-19 March 2015,
[3] US 6,320,490.

1000 Electromagnetic induction device, core 2000 Core 2100 Main pier 2110 End 2201 Side pier 2301 Leakage pier 2301a Machining groove 2500, 2600 Lower plate 2510, 2610 Upper plate 3000 Primary coil, 1st coil 3000a Main section, primary section 3000b 1 primary leakage section 3000c 2nd primary leakage section 3001a primary section 4000 secondary coil, 2nd coil 4000a main section, secondary section 4000b 1st secondary leakage section 4000c 2nd secondary leakage section 4001a main section , secondary section

Claims (17)

- a ferromagnetic core comprising a plurality of piers essentially parallel to each other and each extending between two ends, said plurality of piers comprising at least one main pier (2100, 2101, 2102, 2103 , 2104), ferromagnetic including at least one lateral pier (2201, 2202, 2203, 2204) and at least two leaky pier (2301, 2302, 2303, 2304, 2305a, 2305b, 2306a, 2306b, 2307a, 2307b) body core and
- at least one primary coil (3000, 3001, 3002, 3003) and at least one secondary coil (4000, 4001, 4002, 4003), each main section (3000a, 3001a, 3002a, 3003a, 4000a, 4001a, 4002a, 4003a); An electromagnetic induction device (1000) comprising a primary coil and a secondary coil including a leakage section wrapped around a pier. The core has two plates called a lower plate (2600) and an upper plate (2610), each plate facing each other at inner surfaces called a lower inner surface and an upper inner surface, and a plurality of plates between the two plates. 2. The apparatus of claim 1, wherein the pier extends. 3. The apparatus of claim 2, wherein each peer of the plurality of peers has a gap. The gap, called leakage gap, of each of said at least two leaky peers (2301, 2302, 2303, 2304, 2305a, 2305b, 2306a, 2306b, 2307a, 2307b) is greater than or equal to the gap of the other peer, preferably 4. The device of claim 3, wherein the device exceeds strictly . 5. According to claim 3 or 4, the gap of the at least one main pier (2100, 2101, 2102, 2103, 2104) and the gap of the at least one lateral pier (2201, 2202, 2203, 2204) are the same. equipment. 6. A device according to any one of claims 3 to 5, wherein a plane equidistant from the two inner surfaces forms a plane of symmetry of the core. Machined grooves (2301a, 2302a, 2303a, 2304a) are formed on both of the inner surfaces at intervals so as to at least partially surround each of the two ends of each leak pier, and the machined grooves (2301a, 7. The apparatus according to any one of claims 3 to 6, wherein the leaky peer (2302a, 2303a, 2304a) is sandwiched between the leaky peer and the main peer (2100, 2101, 2102, 2103, 2104). 8. The apparatus of any one of claims 1 to 7, wherein each pier of the plurality of peers is cylindrical. said at least one main pier comprises only one main pier (2100), said at least one lateral pier (2201, 2202, 2203, 2204) arranged regularly around said main pier (2100); 9. A device according to any one of claims 1 to 8, comprising four lateral piers. Said at least two leaky peers (2301, 2302, 2303) comprise four leaky peers arranged regularly around said main pier (2100), advantageously all said leaky peers are connected to said side peers. 10. The device according to claim 9, having an angular offset of 45[deg.] with respect to . The primary leakage section comprises two primary leakage sections, the primary coil including in order one of the primary leakage sections, the main section and the other primary leakage section, the primary leakage section comprising: 11. The device according to claim 10, each wrapped around different, advantageously diametrically opposed leakage piers. The secondary leakage section is configured to include two secondary leakage sections, the primary coil including in order one of the secondary leakage sections, the main section, and the other secondary leakage section; 12. Apparatus according to claim 10 or 11, wherein the sub-leakage sections are each wrapped around different, advantageously diametrically opposed, leakage piers. The at least one main peer (2101, 2102, 2103, 2104) consists of three main peers together with the at least one side peer, each main peer having its own set of two leaks. 9. A device according to any preceding claim, in combination with a peer (2304, 2305a, 2305b, 2306a, 2306b, 2307a, 2307b). 14. The apparatus of claim 13, wherein the three main piers are regularly arranged around a main axis parallel to them. Said two leaky peers (2304, 2305a, 2305b, 2306a, 2306b, 2307a, 2307b) of a given set of peers are diametrical with respect to said main peer (2101, 2102, 2103, 2104) with which they are combined. 15. The device according to claim 14, opposite to. 16. The apparatus of claim 15, wherein the two leaky peers (2304, 2305a, 2305b, 2306a, 2306b, 2307a, 2307b) of the set of peers are arranged symmetrically with respect to a plane passing through the principal axis. 17. A transformer equipped with a device according to any one of claims 1 to 16.

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