HK1190499B - Integrated magnetics for soft switching converter - Google Patents

Description

Integrated magnetics for soft-switching converters

Technical Field

The present invention relates to an integrated magnetic component for a switch-mode power converter, comprising two magnetic cores forming a figure-eight core structure and at least two first electrical winding wires, wherein the first magnetic core is an E-core. Furthermore, the present invention relates to an integrated magnetic component, a method for manufacturing an integrated magnetic component, a soft-switching converter, and an LLC resonant converter according to the parallel independent claims.

Background Art

Switched-mode power supplies, key components in telecommunications and commercial systems, typically have their size and electrical performance, along with reliability and cost, dictated by requirements. As the demands on key performance characteristics of power converters (such as power density and efficiency) increase, the demands on these key characteristics are particularly high for inductive components. One approach to improving power density and efficiency in such systems is to integrate the inductive components. For example, the transformer and inductor can be integrated into a single magnetic structure, reducing cost, increasing power density, and, equivalently, improving power efficiency.

One circuit where integrated magnetics are particularly advantageous is a soft-switching converter (US Pat. No. 6,862,195), capable of achieving high efficiency while operating at high switching frequencies. A typical soft-switching converter uses three magnetic components: a parallel resonant inductor, a two-winding transformer, and a series filter inductor. Besides increasing the number of discrete magnetic components, which results in higher size and cost, the converter also requires at least three windings and multiple interconnections, which negatively impacts efficiency.

The shunt primary resonant inductor and transformer are usually integrated into one component. The air gap in the non-ideal transformer is squeezed hard to adjust the magnetizing inductance that replaces the shunt primary resonant inductor.

In recent years, some efforts have been made to integrate all three magnetic components into a single component for LLC resonant converters. Some integrated magnetic structures are shown in US 2008/0224809. An additional inductor winding is introduced to form the series resonant inductance to enhance the leakage inductance of the transformer.

Although US 2008/0224809 proposes some modest improvements to the typical soft-resonant LLC converter, some drawbacks remain: most use E-cores from retail sources, and bobbins are inevitably used to wrap the coils. Bobbins negatively impact cost, power density, power efficiency, and thermal distribution. Additional power losses occur due to air gap fringing fields and higher average winding lengths. Bobbins are costly and result in more leakage and inductive losses. Additionally, these bobbins reduce power density and increase thermal resistance. Furthermore, the integrated magnetic components disclosed in US 2008/0224809 are relatively complex to manufacture due to their complex geometry, the number of windings, and the relative positions of these windings relative to one another.

Summary of the Invention

The object of the present invention is to create an integrated magnetic component belonging to the initially mentioned technical field, which has a high power density and efficiency, is cheap and easy to manufacture and has a simple design.

The solution of the present invention is specified by the features of claim 1. In an integrated magnetic component for a switch-mode power converter (particularly for a soft-switching converter and/or for an LLC resonant converter) according to the present invention, comprising two magnetic cores (wherein the first magnetic core is an E-core) forming a figure-eight core structure and at least two first electrical winding wires, at least one of the first electrical winding wires is wound around a flange of the E-core. A "flange" is to be understood as one of the two vertical portions of an upright E-core that separate the three horizontal legs of the upright E-core from one another. The term "E-core" is to be understood as "E-core and/or ER-core," wherein an ER-core describes an E-core in which the central leg of the E-core is cylindrical and/or the lateral legs of the E-core have at least partially circular side portions, particularly circular inner portions.

Using the flanges of the E-core instead of legs to place the windings facilitates a straightforward manufacturing process and results in high power density and efficiency of the integrated magnetic components.

In a preferred embodiment, the second magnetic core of the figure-eight core structure is an E-core. Using an E-core as the second magnetic core has the following advantages: the two magnetic cores have at least approximately the same shape; thus, the manufacture of the integrated magnetic component and its handling are optimized. In another typical embodiment, the figure-eight core structure is an I-core. Using an I-core has the advantage that it is extremely easy to handle. However, the second magnetic core can also have a different shape. For example, it can be a U-core. In the latter case, the central leg of the first magnetic core (typically an E-core) is preferably longer than the two lateral legs of this particular first magnetic core.

In a preferred embodiment, the integrated magnetic component includes at least two second electrical winding wires. Preferably, the first magnetic core includes one first electrical winding wire and one second electrical winding wire. Preferably, the second magnetic core also includes one first electrical winding wire and one second electrical winding wire. The use of at least two second electrical winding wires in addition to the first electrical winding wire has the advantage that electrical insulation between the two sides of the integrated magnetic component can be easily achieved. However, the use of at least two electrical winding wires is not absolutely necessary. It is also possible to use only one second electrical winding wire.

In a typical embodiment, at least one electrical winding is wound directly onto one of the magnetic cores. This means that no bobbins are used. The omission of a bobbin has the advantage that it leads to a significant improvement in the utilization of the winding window compared to designs in which the bobbin is located between the electrical winding wire and the magnetic core. This increased window utilization is associated with an increase in power density. Another advantage is that the thermal resistance between the core and the winding is reduced. This leads to improved efficiency of the integrated magnetic component. In a typical embodiment, all electrical winding wires are wound directly onto the magnetic core. However, it is also possible to wind only some of the electrical winding wires (for example, only the first electrical winding wire) directly onto the magnetic core and to use bobbins for the remaining electrical winding wires (for example, the second electrical winding wire).

In a preferred embodiment, the first electrical winding wires are connected to each other by means of a first welded joint and/or the second electrical winding wires are connected to each other by means of a second welded joint. This has the advantage that the production of the integrated magnetic component is simplified, since the first magnetic core and the second magnetic core can be easily connected and assembled to form an integrated magnetic structure in this way, wherein typically a first electrical winding wire and a second electrical winding wire are at least partially wound around the first magnetic core and typically a first electrical winding wire and a second electrical winding wire are also at least partially wound around the second magnetic core. However, the use of welded joints is not mandatory. The connection between the respective wires can also be adapted in different ways to establish a suitable electrical and/or mechanical connection.

In a preferred embodiment, at least one of the first electrical winding wires comprises and/or forms two windings. Preferably, each of the two first electrical winding wires comprises and/or forms two windings. However, it is also possible that the first electrical winding wire forms only one winding or more than two windings. In particular, the number of windings can be different for the two first electrical winding wires. One advantage of having one electrical winding comprising and/or forming two windings is that the overall number of electrical winding wires required to manufacture the integrated magnetic component is reduced. Consequently, the number of welded joints that need to be created during manufacturing is also reduced. This results in an easier and cheaper manufacturing process.

In typical embodiments, at least one of the second electrical winding wires is wound around a flange of one of the E-cores or around the I-core. It is particularly preferred that one second electrical winding wire is wound around a flange of the first magnetic core (typically an E-core), and, if the second magnetic core is an E-core, one of the second electrical winding wires is wound around the flange of the second magnetic core, or, if the second magnetic core is an I-core, one of the second electrical winding wires is wound around the I-core. Winding at least one of the electrical winding wires in this manner is advantageous because it uniformizes the construction of the integrated magnetic structure and leads to improved electrical properties, such as a favorable flux distribution. However, in principle, the second electrical winding wire can also be wound in a different manner, for example around the legs of the second magnetic core, if the second magnetic core is an E-core.

In a preferred embodiment, the figure-eight core structure includes an air gap. In a particularly preferred embodiment, the figure-eight core structure includes three air gaps, whereby—when the second magnetic core is an E-core—each of the three legs of the first E-core is typically separated from the corresponding leg of the second E-core by an air gap. The presence of an air gap has the advantage of facilitating adjustment of the primary magnetizing inductance, output filter inductance, and transformer turns ratio of the integrated magnetic component. This is particularly advantageous when the air gap is filled with a material having suitable electrical properties (particularly a plastic material). An example of such a suitable electrical property is, for example, non-conductivity, which has the advantage of avoiding additional skin effect losses. However, the presence of an air gap is not mandatory. The integrated magnetic component can also be configured without an air gap, with fewer than three air gaps, or even with more than three air gaps.

In a preferred embodiment, one or more air gaps are centrally located in the figure-8 core structure, which means that: in the case where both magnetic cores are E-cores, the one or more air gaps have the same distance from the flange of each E-core, or in the case where the second magnetic structure is an I-core, the one or more air gaps have the same distance from the flanges of the E-core and the I-core. Preferably, the one or more air gaps are approximately parallel to the flanges of the E-core and/or the I-core. This arrangement of the air gaps has the following advantages: very appropriate flux management and high efficiency of the integrated magnetic component can be obtained. In particular, this arrangement of the air gaps produces a sharp reduction in AC copper losses caused by the air gap stray fields. However, it is also possible that the one or more air gaps are not centrally located, and/or the air gaps are not approximately parallel to the flanges of these E-cores and/or I-cores, and/or the distances are not the same.

In a preferred embodiment, the figure-eight core structure and/or at least one of the magnetic cores includes a beveled edge. Compared to a sharp edge (i.e., an edge at approximately 90°), a beveled edge has the following advantages: it is less sharp; therefore, the electrical winding wire directly wound onto at least one of the magnetic cores is less susceptible to damage by the sharp edge. Instead of a beveled edge, an at least partially rounded or rounded edge can also be used. In principle, any edge type is suitable, as long as it is not sharp enough to damage the electrical winding wire.

In a typical embodiment, three windings are wound around each magnetic core. When both magnetic cores are E-cores, it is particularly preferred to wind one winding around the first flange of each E-core and two windings around the second flange of each E-core. When one magnetic core is an E-core and the other magnetic core is an I-core, it is particularly preferred to wind one winding around the first flange of the E-core, two windings around the second flange of the E-core, and three windings continuously around the I-core.

In an integrated magnetic component according to the present invention comprising a magnetic core in the form of an E-core and two electrical winding wires, the electrical winding wires are wound around the flanges of the E-core. Preferably, these wires are wound axially (i.e., directly) around the flanges. In a typical embodiment, the winding wires are used to wind two windings around one flange of the E-core and one winding around the other flange of the E-core.

A method for manufacturing an integrated magnetic component according to the present invention comprises the following steps:

- providing a first winding by winding a first electrical winding wire around a first flange of a first E-core;

- providing a second winding by winding the first electrical winding wire around a second flange of the first E-core;

- providing a fifth winding by winding a second electrical winding wire around a second flange of said first E-core;

- providing a tertiary winding by winding a complementary first electrical winding wire around the first flange of the second E-core or around the I-core;

- providing a fourth winding by winding the supplementary first electrical winding wire around a second flange of the second E-core or around the I-core; and

- providing a sixth winding by winding a supplementary second air winding wire around a second flange of the second E-core or around the I-core.

In a preferred method for manufacturing an integrated magnetic component, the first E-core and the second E-core or the I-core are fixed to each other, the first electrical winding wires are welded to each other, and the second electrical winding wires are welded to each other, preferably after the six windings have been wound on the core.

A soft-switching converter according to the invention comprises an integrated magnetic component according to the invention.

An LLC converter according to the invention comprises an integrated magnetic component according to the invention.

The integrated magnetic component according to the present invention has a compact assembly, which results in a reduction of copper losses and an overall reduction of stray inductance.The transient characteristics of the converter are equally improved.

Further advantageous embodiments and feature combinations are disclosed from the following detailed description and the entirety of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings for illustrating the embodiments show:

FIG1 is an equivalent circuit of a soft-switching converter circuit, which is one possible circuit in which an integrated magnetic component according to the present invention may be used;

FIG2 is an equivalent circuit of an LLC resonant converter circuit, which is another possible circuit in which the integrated magnetic component according to the present invention may be used;

FIG3 is a schematic diagram of an integrated magnetic component according to the present invention (first embodiment);

FIG4 is a magnetoresistance model of the embodiment of FIG3 ;

FIG5 is a run of curves of voltage and current in the secondary transformer winding and flux density (induction) in the transformer core legs, choke core legs, and center leg;

FIG6 is a schematic diagram of an integrated magnetic component according to the present invention (second embodiment);

FIG7 is a magnetoresistance model of the embodiment of FIG6; and

FIG8 is a run of curves for series resonant choke current, parallel resonant choke current and primary winding current, as well as flux density (induction) in the transformer core legs, choke core legs and center leg.

In the drawings, the same components are given the same reference symbols.

DETAILED DESCRIPTION

Figure 1 shows the equivalent circuit of a soft-switching converter circuit, one possible circuit in which the integrated magnetic component according to the present invention can be used. The soft-switching converter circuit includes an input circuit comprising four switching devices Q1, Q2, Q3, and Q4 and an input capacitor _Cin ; an output circuit comprising four diodes D1, D2, D3, and D4 and an output capacitor _Co ; and an integrated magnetic component 1 according to the present invention. The equivalent circuit of integrated magnetic component 1 includes two output filter chokes _Lr1 and _Lr2 , a parallel resonant inductor _Lm , and a transformer T.

Figure 2 shows an equivalent circuit of an LLC resonant converter circuit, another possible circuit in which the integrated magnetic component according to the present invention can be used. The LLC resonant converter circuit includes an input circuit comprising two switching devices Q1 and Q2 and an input capacitor _Cin ; an output circuit comprising two diodes D1 and D2 and an output capacitor _Co ; and an integrated magnetic component 1a according to the present invention. The equivalent circuit of integrated magnetic component 1a includes a parallel resonant inductor _Lm , a transformer T, and two input resonant inductors _Lr1 and _Lr2 .

Figure 3 shows a schematic diagram of an integrated magnetic component 1 according to the present invention. The integrated magnetic component 1 comprises an 8-shaped core structure 2, which comprises a first magnetic core 3.1 and a second magnetic core 3.2. Both magnetic cores 3.1 and 3.2 are in the form of E-cores.

A first electrical winding wire 4.1 is wound around the first magnetic core 3.1. The first electrical winding wire 4.1 includes a first winding 5.1 wound around a first flange of the first magnetic core 3.1 and constituting a winding of a first output filter choke L _r1 ; and a second winding 6.1 wound around a second flange of the first magnetic core 3.1 and constituting a first secondary winding S1 of the transformer T. A supplementary first electrical winding wire 4.2 is wound around the second magnetic core 3.2. The supplementary first electrical winding wire 4.2 includes a third winding 5.2 wound around a first flange of the second magnetic core 3.2 and constituting a winding of a second output filter choke L _r2 ; and a fourth winding 6.2 wound around a second flange of the second magnetic core 3.2 and constituting a second secondary winding S2 of the transformer T. The first electrical winding wire 4.1 and the supplementary first electrical winding wire 4.2 are connected to each other via a first welded joint 7.1. First electrical winding wire 4.1 includes a connecting portion 8.1 that connects first winding 5.1 to second winding 6.1. Similarly, supplementary first electrical winding wire 4.2 includes a connecting portion 8.2 that connects third winding 5.2 to fourth winding 6.2. Connecting portions 8.1 and 8.2 are positioned on opposite sides of the figure-eight core structure 2. First electrical winding wire 4.1 includes a wire end portion 10.1, and supplementary first electrical winding wire 4.2 includes a wire end portion 10.2. Wire end portions 10.1 and 10.2 are positioned on opposite sides of the figure-eight core structure 2.

A second electrical winding wire 9.1 is wound around the second flange of the first magnetic core 3.1, thereby creating a fifth winding 12.1 constituting the first primary winding P1 of the transformer T. A supplementary second electrical winding wire 9.2 is wound around the second flange of the second magnetic core 3.2, thereby creating a sixth winding 12.2 constituting the second primary winding P2 of the transformer T. The second electrical winding wire 9.1 and the supplementary second electrical winding wire 9.2 are connected to each other via a second welded joint 7.2. The second electrical winding wire 9.1 includes a wire end portion 10.3, and the supplementary second electrical winding wire 9.2 includes a wire end portion 10.4. The wire end portions 10.3 and 10.4 are positioned on opposite sides of the figure-eight core structure 2.

The wire end portions 10 . 1 and 10 . 3 and the connecting portion 8 . 1 are placed on one side of the figure-8 core structure 2 , while the wire end portions 10 . 2 and 10 . 4 and the connecting portion 8 . 1 are placed on the other side of the figure-8 core structure 2 .

The figure-eight core structure 2 includes three air gaps 11.1, 11.2, and 11.3. The air gaps 11.1 and 11.3 separate the two lateral legs of each core 3.1, 3.2 from the corresponding lateral legs of the other core 3.1, 3.2. The central legs of the cores 3.1, 3.2 are separated by the air gap 11.2.

The six windings 5.1, 5.2, 6.1, 6.2, 12.1, and 12.2 are wound directly (i.e., without a spool) on four flanges of a figure-eight core structure 2, which is fed by two cores 3.1 and 3.2. Each of the core structures 3.1 and 3.2 includes a plurality of beveled edges 13. These beveled edges 13 are less likely to damage the electrical winding wires 4.1, 4.2, 9.1, and 9.2 than sharp 90-degree edges.

The introduction of the air gap 11.1 in the flux path of the transformer T corresponds to the integration of the transformer T and the parallel resonant inductor _Lm (see Figure 1). The parallel inductance thus created is adjustable by the configuration of the air gap 11.1, while the turns ratio of the transformer T remains unchanged.

The cancellation of the flux in this common central leg and thus the reduction of the core losses is caused by the fact that the cores of the gapped transformer T and the output filter chokes L _r1 and L _r2 are placed together in a common central leg consisting of the two central legs of the magnetic cores 3 . 1 and 3 . 2 .

The integrated structure (shown in FIG1 ) of the inductors L _m , L r1 _, and L _r2 , along with the transformer T, including a parallel input inductor L _m , a transformer T, and coupled output filter chokes L _r1 and L _r2 wound on a wireless axis E-core as shown in FIG3 , can be summarized as follows: The structure includes two magnetic cores 3.1 and 3.2 formed as E-cores (the use of ER cores is also possible), three air gaps 11.1 , 11.2 , and 11.3 , and six windings 5.1 , 5.2 , 6.1 , 6.2 , 12.1 , and 12.2 . Windings 12.1 and 12.2 constitute the two primary windings P1 and P2 of the transformer T. Windings 6.1 and 6.2 constitute the two secondary windings S1 and S2 of the transformer T. Windings 5.1 and 5.2 constitute the windings of the first and second output filter chokes L _r1 and L _r2 . The first and second output filter chokes L _r1 and L _r2 are symmetrically wound on different flanges and optimally coupled.

FIG4 shows the corresponding reluctance model for the embodiment of FIG3 . _RL represents the reluctance of the inductive core (e.g., the right lateral leg and lateral flange of the magnetic cores 3.1 and 3.2 shown in FIG3 ) taking into account its corresponding air gap 11.3, _RT represents the reluctance of the transformer core (e.g., the left lateral leg and lateral flange of the magnetic cores 3.1 and 3.2 shown in FIG3 ) taking into account its corresponding air gap 11.1, and _Rc represents the reluctance of the central core (consisting of the two central legs of the magnetic cores 3.1 and 3.2) taking into account its corresponding air gap 11.2.

After the mathematical description of the reluctance model and the application of Faraday's law to all windings, some equation manipulation yields the inductance matrix of the integrated components calculated as:

in

as well as.

Using the calculated elements of the inductance matrix “primary L ₁₁ , secondary self-inductance L ₂₂ and mutual inductance M ₁₂ ”, the parameters of the transformer π model “magnetizing inductance L _m , secondary leakage inductance L _r and equivalent secondary turns N _sn ” are described as:

_Ns turns are wound, but the transformer exhibits _Nsn turns. By introducing an air gap in the central leg, the effective secondary turns _Nsn becomes higher than the real turns _Ns , which allows reducing the secondary copper losses.

For high permeability, low saturation flux density materials with no air gap in the central core (g ₃ ≈ 0), only R _c << _RL , _RT , the gapped transformer and output filter inductor are magnetically decoupled, and the primary leakage inductance L _r , magnetizing inductance L _m , and equivalent secondary turns N _sn are simplified to:

,as well as.

The flux and flux density () in the transformer leg, the flux and flux density () in the choke leg, and the flux and flux density () in the central leg are calculated as follows:

Where _Im is the transformer magnetizing current.

For a high permeability, low saturation flux density material with no air gap in the central core (g ₃ ≈ 0), only R _c << _RL , _RT , the gapped transformer and output filter inductor are magnetically decoupled, and the transformer leg flux and filter inductor leg flux are simplified to:

Figure 5 illustrates the curves for the voltage and current in the secondary transformer winding, as well as the flux density (inductance) in the core transformer, choke, and center leg. The flux density in the center core leg _Bc is reduced, thus minimizing core losses therein. When the transformer and inductor cores are completely separated, the flux flowing through all transformer legs is , and the flux flowing through all inductor legs is .

A second embodiment of the invention is shown in Figure 6. The integrated magnetic component 1a comprises a figure-8 core structure 2a consisting of two magnetic cores 3.1a and 3.2a and is suitable for an LLC resonant converter like the one shown in Figure 2.

Similar to the embodiment shown in FIG3 , the integrated magnetic component 1 a includes a first electrical winding wire 4.1 a and a supplementary first electrical winding wire 4.2 a. The first electrical winding wire 4.1 a includes a wire end portion 10.1 a, a first winding 5.1 a, a connecting portion 8.1 a, and a second winding 6.1 a. The supplementary first electrical winding wire 4.2 a includes a wire end portion 10.2 a, a third winding 5.2 a, a connecting portion 8.2 a, and a fourth winding 6.2 a. The first electrical winding wire 4.1 a and the supplementary first electrical winding wire 4.2 a are connected to each other via a welded joint 7.1 a.

Also similar to the embodiment shown in FIG3 , the integrated magnetic component 1 a includes a second electrical winding wire 9.1 a and a supplementary second electrical winding wire 9.2 a. The second electrical winding wire 9.1 a includes a wire end portion 10.3 a and a fifth winding 12.1 a. The supplementary second electrical winding wire 9.2 a includes a wire end portion 10.4 a and a sixth winding 12.2 a. The second electrical winding wire 9.1 a and the supplementary second electrical winding wire 9.2 a are connected to each other via a welded joint 7.2 a.

The figure-eight core structure 2a includes three air gaps 11.1a, 11.2a, and 11.3a. The air gaps 11.1a and 11.3a separate the two lateral legs of each core 3.1a, 3.2a from the corresponding lateral legs of the other core 3.1a, 3.2a. The central legs of the cores 3.1a, 3.2a are separated by the air gap 11.2a.

The six windings 5.1a, 5.2a, 6.1a, 6.2a, 12.1a, and 12.2a are wound directly (i.e., without a spool) on four flanges of a figure-eight core structure 2a, which is fed by two cores 3.1a and 3.2a. Each of the core structures 3.1a and 3.2a includes a plurality of angled edges 13a. These angled edges 13a are less likely to damage the electrical winding wires 4.1a, 4.2a, 9.1a, and 9.2a than sharp 90-degree edges.

The integrated magnetic component 1a comprises an output line 14 connected to the welded joint 7.2a.

Compared to the embodiment shown in FIG. 3 , all the end portions 10 . 1 a , 10 . 2 a , 10 . 3 a and 10 . 4 a and the connecting portions 8 . 1 a and 8 . 2 a are placed on the same side of the figure-8-shaped structure 2 a .

Referring to Figures 6 and 2, the first winding 5.1a is wound around the first flange of the first magnetic core 3.1a constituting the winding of the first resonant inductor _Lr1 . The second winding 6.1a is wound around the second flange of the first magnetic core 3.1a constituting the first primary winding P1 of the transformer T. The third winding 5.2a is wound around the first flange of the second magnetic core 3.2a constituting the winding of the second resonant inductor _Lr2 . The fourth winding 6.2a is wound around the second flange of the second magnetic core 3.2a constituting the second primary winding P2 of the transformer T. The fifth winding 12.1a is wound around the second flange of the first magnetic core 3.1a constituting the first secondary winding S1 of the transformer T. The sixth winding 12.2a is wound around the second flange of the second magnetic core 3.2a constituting the second secondary winding S2 of the transformer T.

FIG7 shows the corresponding reluctance model for the embodiment of FIG6 . _RL represents the reluctance of the inductive core (e.g., the left lateral leg and lateral flange of the cores of cores 3.1a and 3.2a shown in FIG6 ) taking into account its corresponding air gap 11.3a, _RT represents the reluctance of the transformer core (e.g., the right lateral leg and lateral flange of the core legs of cores 3.1a and 3.2a shown in FIG6 ) taking into account its corresponding air gap 11.1a, and _Rc represents the reluctance of the central core (consisting of the two central legs of cores 3.1a and 3.2a) taking into account its corresponding air gap 11.2a. Following the mathematical description of the reluctance model and the application of Faraday's law to all windings, some equation derivation yields the inductance matrix of the integrated component, which is calculated as follows:

in

as well as.

Using the calculated elements of the inductance matrix “primary L ₁₁ , secondary self-inductance L ₂₂ and mutual inductance M ₁₂ ”, the parameters of the transformer π model “magnetizing inductance L _m , secondary leakage inductance L _r and equivalent primary turns N _pn ” are described as:

as well as

.

_Np turns are wound, but the transformer exhibits _Npn turns. By introducing an air gap in the central leg, the effective number of primary turns _Npn becomes higher than the real number of turns _Np , which allows reducing the primary copper losses.

For high permeability, low saturation flux density materials with no air gap in the central core (g ₃ ≈ 0), only R _c << _RL , _RT , the gapped transformer and resonant inductor are magnetically decoupled, and the primary leakage inductance L _r , magnetizing inductance L _m and equivalent primary turns N _pn are simplified to:

as well as.

The flux and flux density of the legs of this embodiment are calculated as for the integrated magnetics for the soft-switching converter.

Figure 8 illustrates the operation of the curves for the series resonant choke current, the parallel resonant choke current and the primary winding current, as well as the flux density (induction) in the core transformer, the choke and the central leg. The flux density in the central core leg _Bc is reduced and, therefore, the core losses therein are minimized.

It should be noted that the present invention is not limited to the two embodiments described above. Rather, the scope of protection is defined by the patent claims.

Claims (15)

1. An integrated magnetic component (1) for a switching power converter, comprising: - Two magnetic cores (3.1, 3.2) forming the figure-eight core structure (2); and - At least two first electrical windings (4.1, 4.2) and at least two second electrical windings (9.1, 9.2). Among them, the first magnetic core (3.1) is the E core. Its features At least one of the first electrical winding wires (4.1, 4.2) is wound around the flange of the E core; The first electrical windings (4.1, 4.2) are connected to each other and/or the second electrical windings (9.1, 9.2) are connected to each other. 2. The integrated magnetic component (1) according to claim 1, wherein the second magnetic core (3.2) is an E core or an I core. 3. The integrated magnetic component (1) according to claim 1, characterized in that at least one of the electrical winding wires (4.1, 4.2, 9.1, 9.2) is directly wound on one of the magnetic cores (3.1, 3.2). 4. The integrated magnetic component (1) according to claim 3, characterized in that the first electric winding wires (4.1, 4.2) are connected to each other by a first welding joint (7.1), and/or the second electric winding wires (9.1, 9.2) are connected to each other by a second welding joint (7.2). 5. The integrated magnetic component (1) according to claim 1, wherein at least one of the first electric winding wires (4.1, 4.2) comprises two windings (5.1, 5.2, 6.1, 6.2). 6. The integrated magnetic component (1) according to claim 2, wherein at least one of the second electric winding wires (9.1, 9.2) is wound on the flange of one of the E cores or wound on the I core. 7. The integrated magnetic component (1) according to claim 1, wherein the figure-eight core structure (2) includes air gaps (11.1, 11.2, 11.3). 8. The integrated magnetic component (1) according to claim 7, wherein the air gaps (11.1, 11.2, 11.3) are concentrated in the figure-eight core structure (2). 9. The integrated magnetic component (1) according to claim 1, wherein the figure-eight core structure (2) includes an inclined edge (13). 10. The integrated magnetic component (1) according to claim 1, characterized in that three windings (5.1, 5.2, 6.1, 6.2, 12.1, 12.2) are wound on each magnetic core. 11. An integrated magnetic element for use in an integrated magnetic component according to any one of claims 1 to 10, comprising a magnetic core (3.1, 3.2) having an E-core and two electrical windings, characterized in that the electrical windings are wound around a flange of the magnetic core. 12. A method for manufacturing an integrated magnetic component (1), characterized by the following steps: - The first winding (5.1) is provided by winding the first electrical winding wire (4.1) around the first flange of the first E core (3.1); - A second winding (6.1) is provided by winding the first electrical winding wire (4.1) around the second flange of the first E core (3.1). - A fifth winding (12.1) is provided by winding a second electrical winding wire (9.1) around the second flange of the first E core (3.1). - A third winding (5.2) is provided by wrapping the supplementary first electrical winding wire (4.2) around the first flange of the second E core (3.2) or around the I core. - A fourth winding (6.2) is provided by winding the supplementary first electrical winding wire (4.2) around the second flange of the second E core (3.2) or around the I core; and - A sixth winding (12.2) is provided by winding a supplementary second electrical winding wire (9.2) around the second flange of the second E core (3.2) or around the I core. - Connect the first electrical winding wires (4.1, 4.2) to each other; and - Connect the second electrical winding wires (9.1, 9.2) to each other. 13. The method according to claim 12, characterized in that... - The first E-core (3.1) and the second E-core (3.2) are fixed to each other. - The first electrical winding wires (4.1, 4.2) are soldered to each other, and - The second electrical winding wires (9.1, 9.2) are welded to each other. 14. A soft-switching converter comprising the integrated magnetic component (1) according to any one of claims 1 to 10. 15. An LLC converter comprising the integrated magnetic component (1) according to any one of claims 1 to 10.