Multi-phase transformer and LLC resonant converter

Abstract

The invention relates to a multiphase transformer (1) comprising: at least one magnetic core part (2) comprising a main body part (3) and a plurality of leg parts (4) extending from the main body part (3) in a leg extension direction (5); a primary side having a plurality of primary conductors (6), wherein each primary conductor (6) is wound around a respective leg (4); and a secondary side having a plurality of secondary conductors (7), each of which at least partially surrounds one leg (4), the secondary conductors (7) being interconnected in an electrical star configuration; wherein the primary conductor (6) and the secondary conductor (7) are stacked in the leg extension direction (5), and the star point (8) on the secondary side is arranged at least geometrically in a position within a virtual boundary (9) defined by the outer boundary of the at least one magnetic core part (2) and / or the primary conductor (6). The invention also relates to an LLC resonant converter (100) comprising the above multiphase transformer (1).

Description

Technical Field

[0001] The present invention relates to a multi-phase transformer and an LLC resonant converter comprising the multi-phase transformer. Background Art

[0002] Multiphase transformers and converters including such transformers, in particular three-phase transformers / converters, are known, for example from US2013 / 0201725A1, US2019 / 0013741A1 and CN101841244A. Such transformers are typically used for high current applications (i.e., several hundred amperes). However, they typically have the disadvantage of a long secondary winding length. In addition, the star or delta connection configuration of the secondary winding requires very long connections, which increases losses and increases parasitic inductances that reduce the maximum available power transfer. In addition, a discrete resonant inductor is required, which increases losses in the overall system.

[0003] Specifically, US2013 / 0201725A1 discloses Figure 4 A transformer is disclosed in US2013 / 0201725A1, which has a primary winding in a triangle configuration and a secondary winding connected in a star configuration. The secondary winding includes a secondary common node, which is the common point of the star-configured transformer, that is, the common point of the star-configured secondary windings. Such a common point is also commonly referred to as a "star point". However, US2013 / 0201725A1 does not mention the geometric and / or electrical positioning of the secondary common node. In its practical application, the winding length (especially the winding length on the secondary side) is relatively long.

[0004] Usually, especially for high current transformers and their applications, secondary side winding losses are dominant, since usually only one secondary turn is used. In addition, when a plurality of such transformers are provided in parallel (depending on the number of phases), the connections between the secondary windings are very long, so that the winding losses increase significantly. Summary of the invention

[0005] The object of the present invention is to provide a multiphase transformer and LLC resonant converter that overcomes the above challenges. In particular, the object of the present invention is to provide a multiphase transformer and LLC resonant converter with reduced secondary winding length, and further avoid the use of bulky and lossy resonant inductors, thereby reducing losses and improving maximum available power transfer and efficiency.

[0006] In particular, the solution to this object is achieved by a multiphase transformer according to the following description. The multiphase transformer comprises at least one core component, which comprises a main body and a plurality of leg portions extending from the main body in a leg extension direction. In addition, the transformer comprises a primary side with a plurality of primary conductors and a secondary side with a plurality of secondary conductors. Each primary conductor is wound around a leg portion, respectively. The secondary conductors respectively at least partially surround a leg portion and are interconnected in an electrical star configuration. The primary conductors and the secondary conductors are stacked in the leg extension direction. In addition, the star point of the secondary side is at least geometrically arranged at a position within an imaginary boundary defined by the outer boundaries of the at least one core component and / or the primary conductor.

[0007] The secondary conductor thus forms an integrated stray magnetic field within the transformer, which can be used to avoid bulky and lossy resonant inductors. Furthermore, the winding length, ie the length of the conductor, is significantly reduced, especially on the secondary side, so that the winding losses are advantageously reduced.

[0008] Preferably, the virtual boundary is a virtual plane or a virtual volume defined by the outer dimensions of at least one magnetic component or a plurality of primary conductors. In other words, the virtual boundary may be two-dimensional, i.e. a plane (e.g. a cross section), or may be three-dimensional, i.e. a volume. In particular, the virtual boundary is defined by one or more of the above-mentioned components of the transformer (except the secondary conductor), which define the outer dimensions of the transformer. For example, if the transformer is placed on or against a planar surface, one or more components (except the secondary conductor) in contact with the surface, in particular their respective surfaces or points, will define the outer dimensions of the transformer. The star point of the secondary conductor is at least geometrically arranged within the virtual volume or boundary.

[0009] The term "at least geometrically" is to be understood as characterizing in particular the arrangement of the star point in space. In addition, the term can be understood as "geometrically and electrically", thus characterizing the arrangement in space as well as the electrical arrangement, ie the arrangement with respect to electrical lengths.

[0010] In some preferred embodiments, the position of the star point of the secondary conductor is at least geometrically the center position of the transformer between the legs. In particular, the center position is defined by the middle point of at least one virtual line, which spans the shortest distance between at least two separated legs of at least one core component. For example, if exactly two separated legs are taken, the center position is defined as the middle point between these two legs. In addition, if, for example, three legs are taken, a middle point is defined between the first leg and the second leg, another middle point is defined between the second leg and the third leg, and yet another middle point is defined between the first leg and the third leg. The center position is then the combined projection of the above middle points, such as the center of a triangle defined by three virtual lines spanning between the three legs.

[0011] Preferably, the star point of the secondary conductor is located at the center of a triangle defined by three imaginary lines respectively spanning between the three legs.

[0012] Preferably, the position of the star point is also arranged within the virtual boundary relative to the leg extension direction. For example, the star point is arranged within the virtual boundary, and the virtual boundary is not linearly translated in the leg extension direction beyond the boundary (in the leg extension direction) of at least one magnetic core component and / or the primary conductor. This preferably corresponds to the above-mentioned three-dimensional virtual boundary.

[0013] Preferably, the star point is arranged at the above-mentioned center position within an error range. In other words, the positioning of the star point may have an error range. The error range may be defined as 20% of the distance between the leg portions (i.e., the length of the above-mentioned one or more virtual lines), preferably 10%, more preferably 5% or 2% or less. The error range is preferably from the theoretical (ideal) center position, along the above-mentioned line spanning the shortest distance, to one of the leg portions plus or minus one of the above-mentioned percentage values.

[0014] In some preferred embodiments, the secondary side comprises at least one plate, wherein portions of the plate respectively define secondary conductors. In other words, one plate (of the at least one plate) defines a plurality of secondary conductors. The dimensions of the plate in its respective length and width are substantially greater than its thickness.

[0015] Alternatively, "plurality of secondary conductors" may also be referred to as "plurality of secondary conductor portions", particularly when referring to parts of a single electrical conductor, such as where a board defines a plurality of secondary conductors.

[0016] Preferably, the plate is a solid copper plate.

[0017] Preferably, each secondary conductor is defined as a portion of at least one plate adjacent to (in particular at least partially surrounding) a respective leg portion of at least one magnetic core component.

[0018] In particular, portions of at least one plate are distinguished as different secondary conductors according to being closer to or more adjacent to a certain leg portion. For example, if a portion (or all) of at least one plate is arranged, for example, between two leg portions, a midline of the portion of the plate can divide the portion into a first portion as a first secondary conductor and a second portion as a second secondary conductor, wherein the midline is defined as the middle of the portion of the plate directly between the two leg portions (i.e., along the shortest distance between the two leg portions).

[0019] Preferably, the current induced in secondary conductors being adjacent parts of the at least one plate may differ between the secondary conductors, in particular differ in direction, in particular depending on the direction of the induced magnetic flux in the respective leg portion.

[0020] The secondary conductors each at least partially surround a leg portion. Preferably, each secondary conductor only partially surrounds a leg portion. In other words, each secondary conductor is arranged to only partially, i.e. not completely, surround a leg portion. Here, the term "surrounding" essentially means extending along the circumference of the leg portion.

[0021] Preferably, the term "partially surrounding" means that the conductor is arranged adjacent to the leg portion, in particular having a curvature or shape corresponding to the curvature or shape of the adjacent surface of the leg portion, rather than being completely wound around the above-mentioned leg portion. In particular, the corresponding conductor induces an induced magnetic flux in the corresponding leg portion, and / or the magnetic flux in the corresponding leg portion induces an induced current or an induced voltage in the corresponding conductor. The induction of the above-mentioned magnetic flux and / or current refers to substantial induction, that is, in particular those inductions oriented to the basic functions of the transformer, rather than, for example, stray fields that are not directly involved in the current transformation.

[0022] Preferably, in case sections of the plate respectively define a secondary conductor, a point on the plate is defined as the star point of the secondary side.

[0023] In some preferred embodiments, the geometric center of the at least one plate corresponds to the star point of the secondary conductor, wherein the geometric center of the at least one plate is geometrically arranged at a position within a virtual boundary defined by the outer boundary of the at least one core component and / or the primary conductor.

[0024] Advantageously, the geometrical centre of at least one plate corresponds, relative to a plane perpendicular to the direction of extension of the legs, to the geometrical centre of at least one core part and / or the primary conductor, in particular to the geometrical centre of at least one body of at least one core part.

[0025] Advantageously, at least one plate is star-shaped. Here, the term "star-shaped" refers to a shape such as an asterisk or a three-pointed star or a cross or a plus sign or an x. Preferably, when referring to the shape of a plate, it is meant the shape of the plate along its width and height, in particular not along its thickness. In particular, it is meant the shape of the plate in a plane perpendicular to the direction in which the legs extend.

[0026] Preferably, each star plate comprises a middle portion and a plurality of extension portions, wherein the extension portions extend from the middle portion, wherein the star point of the secondary conductor is located in the middle portion.

[0027] Preferably, the star shape is symmetrical with respect to the extension. For example, a symmetrical three-pointed star shape or an x ​​or plus sign are examples of symmetrical star shapes. Preferably, the star shape is point symmetrical with respect to its geometric center.

[0028] Preferably, the intermediate portion and the plurality of extension portions are formed integrally with each other.

[0029] Advantageously, the geometrical centre of the star plate corresponds to the above-mentioned centre position of the transformer between the legs, in particular within the above-mentioned tolerance range.

[0030] Preferably, the number of at least one star-shaped plate is plural, and the extensions of the plural star-shaped plates are connected to each other via at least one plate-shaped connecting conductor. Preferably, each connecting conductor extends along the extension direction of the legs.

[0031] Advantageously, at least one plate-shaped connecting conductor is formed integrally with at least one extension of at least one star-shaped plate. In particular, at least one plate-shaped connecting conductor is preferably formed by bending the extension of the star-shaped plate.

[0032] In some embodiments, the star point of the secondary conductor is not located at least geometrically at the center position of the transformer along the direction in which the leg extends. In particular, the star point is preferably not within one of the values ​​of the above-mentioned error range relative to the center position of the transformer along the direction in which the leg extends. For example, the star point is not within a range of 10% relative to the center position of the transformer along the direction in which the leg extends.

[0033] Advantageously, the primary conductor is a wire. In particular, the primary conductor is a wire which is completely wound around one leg portion, respectively. In other words, one primary conductor is completely wound around one leg portion, wherein another primary conductor is completely wound around another leg portion, and so on. Each primary conductor preferably comprises a number of turns greater than 1, which corresponds to a predetermined transformation ratio of the transformer. The primary conductor as a wire may also be referred to as a primary winding.

[0034] In some embodiments, the primary conductors and the secondary conductors are stacked alternately. In other words, along the leg extension direction (stacking direction) of one leg portion, the primary conductors and the secondary conductors are stacked so that at least one secondary conductor is sandwiched between two primary conductors, and / or vice versa.

[0035] Advantageously, each of the plurality of primary conductors (respectively surrounding each leg portion) comprises a plurality of primary conductor portions along the leg extension direction of the corresponding leg portion, each primary conductor portion comprising at least one turn surrounding the corresponding leg portion, wherein at least two of the above primary conductor portions sandwich the secondary conductor.

[0036] Advantageously, the primary conductor parts and the secondary conductors are stacked alternately.

[0037] In some advantageous embodiments, the transformer comprises a plurality of plates constituting the secondary conductor, in particular a plurality of star-shaped plates, wherein preferably, the plurality of star-shaped plates are electrically connected to each other.

[0038] Preferably, the primary conductor part and the plurality of plates constituting the secondary conductor are alternately stacked.

[0039] Preferably, the number of legs corresponds to the number of phases of the multi-phase transformer.

[0040] For example, in a preferred case, the multiphase transformer is a three-phase transformer, wherein the transformer preferably comprises three primary conductors, and the number of turns of the primary conductors is particularly adapted to a predetermined turns ratio of the transformer.

[0041] Wherein, at least one magnetic core preferably comprises three legs. The three legs are arranged in a triangular arrangement along their extension direction from a plan view. In other words, a triangle is formed by connecting the middle points of its cross section with virtual lines. In this case, its center position is preferably defined as explained above with respect to the triangle (three virtual lines and their projection center / middle).

[0042] The above-mentioned plane view along the extension direction of the leg portion is preferably defined as a plane view perpendicular to the cross section (i.e., a view toward the cross section), and the cross section is located in a plane perpendicular to the extension direction of the leg. Preferably, the above-mentioned plane view is defined as a plane view perpendicular to the basic dimensions (length and width) of the plate-shaped secondary conductor (i.e., a view toward the basic dimensions).

[0043] In some preferred embodiments, each star-shaped plate comprises a triangular middle portion and three extension portions, each extension portion being arranged between two adjacent leg portions of at least one magnetic core component.

[0044] The secondary conductors are preferably defined as follows. Each secondary conductor includes a portion (specifically, half) of two extensions arranged adjacent to a specific leg portion of at least one magnetic core component, and a portion (specifically, one third) of the middle portion adjacent to the specific leg portion. Therefore, each star plate defines three secondary conductors in total.

[0045] In other words, each extension portion arranged between two adjacent leg portions is a portion of the first secondary conductor adjacent to (and close to) a first one of the two leg portions and a portion of the second secondary conductor adjacent to (and close to) a second one of the two adjacent leg portions.

[0046] Preferably, at least one extension of the star-shaped plate extends between the legs, in particular, between two legs, in a plane view perpendicular to the direction in which the legs extend. In other words, one extension extends between two adjacent legs, and another extension extends between two other adjacent legs, and so on.

[0047] Preferably, the primary conductors are connected in an electrical delta configuration.Thereby, the winding length of the primary conductors is also advantageously reduced.

[0048] The above embodiments (particularly with respect to the configuration of the secondary conductor) have the advantages described above, namely providing a reduced secondary winding length (length of the secondary conductor), thereby reducing winding losses. In addition, the use of a bulky and lossy resonant inductor can be partially or completely avoided. As a result, maximum power delivery and efficiency can be advantageously improved.

[0049] The present invention also relates to an LLC resonant converter. The LLC resonant converter comprises a multiphase transformer according to any one of the above. Thus, the LLC resonant converter provides the above advantages, namely reduced winding losses, and in particular high maximum power delivery and high efficiency.

[0050] In particular, the LLC resonant converter is a three-phase LLC converter including the three-phase transformer according to the aforementioned embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Further details, advantages and features of preferred embodiments of the present invention are described in detail with reference to the accompanying drawings, in which:

[0052] Figure 1 shows a schematic plan view of a multiphase transformer according to a first embodiment of the present invention;

[0053] Figure 2 Shown along Figure 1 A schematic cross-sectional side view of the multiphase transformer shown along line XX';

[0054] Figure 3 shows a simplified schematic plan view of a multiphase transformer according to a first embodiment of the present invention;

[0055] Figure 4 A reluctance model diagram of a multiphase transformer according to a first embodiment is shown;

[0056] Figure 5shows a schematic cross-sectional side view of a multiphase transformer according to a second embodiment of the present invention; and

[0057] Figure 6 A circuit diagram of an LLC resonant converter including a multi-phase transformer according to the present invention is shown.

[0058] Reference numerals

[0059] 1 Multiphase Transformer

[0060] 2 Core components

[0061] 3 Main body

[0062] 4 Legs

[0063] 5 Outrigger extension direction

[0064] 6 Primary Conductor

[0065] 7 Secondary conductor

[0066] 8 Star Points

[0067] 9 Virtual Boundaries

[0068] 10 Conductor

[0069] 11 Central Location

[0070] 12 Air Gap

[0071] 13 Dotted Line

[0072] 14 Extension

[0073] 15 Middle

[0074] 16 Midpoint

[0075] 17 Virtual Line

[0076] 18 Secondary Connection Points

[0077] 19 Connecting conductor

[0078] 20 Center position (leg extension direction)

[0079] 100LLC resonant converter DETAILED DESCRIPTION

[0080] Figure 1 A schematic plan view of a multiphase transformer 1 according to a first embodiment of the present invention is shown. Figure 2 Shown along Figure 1 A schematic cross-sectional side view of the line XX' of the multiphase transformer 1 is shown;

[0081] refer to Figure 1 and Figure 2 The multiphase transformer 1 (hereinafter referred to as "transformer 1") comprises a plurality of core components 2, in particular two core components 2. Each core component 2 comprises a main body 3 and three leg portions 4 extending therefrom along a leg extension direction 5. However, the number of leg portions 4 is not limited to three. Instead, the number of leg portions 4 corresponds in particular to the number of phases of the transformer 1. Preferably, the transformer 1 is a three-phase transformer and therefore comprises three leg portions 4. Figure 2 It can be seen that the two core components 2 are arranged opposite to each other corresponding to their leg portions 4 .

[0082] The main body portion 3 is substantially plate-shaped, and the leg portion 4 extends therefrom. A dotted line 13 indicates a virtual line dividing the main body portion 3 and the leg portion 4. In the present embodiment, the main body portion 3 and the leg portion 4 are formed integrally with each other.

[0083] An air gap 12 is formed between adjacent leg portions 4 of the separate core components 2. Additional or alternative air gaps 12 may be provided, which are indicated by dashed lines.

[0084] As in Figure 1 As can be seen in FIG. 1 , the leg portion 4 is arranged in a triangular shape. Therefore, in particular, Figure 1 As can be clearly seen from the dotted lines in the figure, the main body 3 connected to the leg parts 4 comprises a triangular shape. Each leg part 4 has a circular cross section. Alternatively, its cross section can be rectangular, in particular square or oval.

[0085] The transformer 1 comprises a plurality of primary conductors 6. Here, the transformer 1 comprises three primary conductors 6. The primary conductors 6 of this embodiment are wires, which can also be referred to as primary windings. Each primary conductor 6 is wound around one leg 4, in particular, completely wound around one leg 4.

[0086] Furthermore, the transformer 1 comprises a plurality of secondary conductors 7. Here, the secondary conductors 7 are formed from a single plate, in particular made of copper. Figure 1 As can be clearly seen in FIG. 1 , the plate forming the secondary conductor 7 is star-shaped and partially surrounds the inner circumference of each leg portion 4 .

[0087] therefore, Figure 1 and Figure 2 The star plate shown forms three secondary conductors 7 which will now be described.

[0088] The star-shaped plate of the secondary conductor 7 consists of a triangular middle portion 15 and an extension portion 14 extending therefrom (see Figure 1 The number of extensions 14 is not limited to three, and in other embodiments, it may correspond to the number of leg portions 4, in particular the number of phases of the transformer 1. In addition, Figure 1The configuration shows that the star plates 14, 15 have angular edges, especially between the extension 14 and the intermediate portion 15, ie their connection areas. In an alternative modification, these connection areas can be curved, especially concave, so as to advantageously adapt to the round shape of the leg portion 4.

[0089] Each secondary conductor 7 is defined by a portion 14, 15 of the plate adjacent to one leg 4 of the core member 2. In other words, the leg 4 defines the secondary conductor 7. Thus, each secondary conductor 7 comprises half of each of the two extensions 14 of the star-shaped plate 14, 15, and one third of the middle portion 15. Thus, a total of three secondary conductors 7 are defined.

[0090] Each end of the extension portion 14 opposite to the middle portion 15 includes a secondary connection point 18 electrically connected to the outside. Figure 6 As will be apparent from the figure, the secondary connection point 18 is connected to, for example, a rectifier leg. In particular, since the secondary conductors 7 are connected via a common middle portion 15, they form an electrical star configuration.

[0091] Furthermore, each secondary conductor 7 is arranged between the legs 4 and only partially surrounds each leg 4 (its corresponding leg 4) in a plane perpendicular to the leg extension direction 5. In particular, each secondary conductor 7 has less than one turn around the corresponding leg 4.

[0092] In the present embodiment, since the secondary conductor 7 is part of a single conductor, ie part of a single star plate 14 , 15 , it may alternatively be referred to as a “secondary conductor portion”.

[0093] In other words, a portion of the star plates 14, 15 in which an induced current is caused by one leg portion 4 corresponds to one secondary conductor 7. Further, another portion in which an induced current is caused by a different leg portion 4 corresponds to a second secondary conductor 7, and so on.

[0094] Alternatively, the extensions 14 may be configured to wrap completely around the respective leg 4, so that the secondary conductor completely surrounds the leg 4. However, in this case, the extensions 14 do not contact the intermediate portion 15 (the ends of the extensions include the connection points 18). For example, they may spiral around the leg 4. Thus, the extensions 14 may define multiple turns of the secondary conductor 7 without causing a short circuit.

[0095] from Figure 2 It can be seen that the primary conductors 6 and the secondary conductors 7 are stacked alternately along the leg extension direction 5 .

[0096] Figure 6The electrical connection configuration of the transformer 1 is shown, as well as optional components of an LLC converter 100 including the transformer 1, which will be discussed below. It can be seen that the secondary conductors 7 are interconnected in an electrical star configuration. In addition, the primary conductors 6 are connected in an electrical delta configuration.

[0097] In the present invention, the star point 8 of the secondary conductor 7 is geometrically arranged within the outer boundary of the magnetic core part 2 and / or the primary conductor 6. This reduces the winding length and the losses associated therewith. Figure 1 ) structure induces a stray magnetic field which can replace the otherwise bulky and lossy resonant inductor in the known transformer. Typically, the star point 8 of the star-connected conductor 7 is defined as the common point (also often referred to as the "neutral point") to which all conductors are connected.

[0098] Will refer to Figure 1 and Figure 3 The arrangement of the star point 8 of the secondary conductor 7 is described.

[0099] Figure 3 1 shows a simplified schematic plan view of a multiphase transformer 1 according to a first embodiment of the present invention. In particular, in order to facilitate the explanation of the arrangement of the star point 8 and the secondary conductor 7, Figure 3 The main body portion 3 of the core member 2 is not shown, nor is the secondary conductor 7 shown.

[0100] As described above, the star point 8 of the secondary conductor 7 is geometrically arranged within the outer boundary of the core member 2 and / or the primary conductor 6. In this embodiment, since the primary conductor 6 includes the core member 2 and the outermost boundary of the primary conductor 6, the outer boundary is defined by a virtual boundary 9 containing the primary conductor 6.

[0101] In particular, the virtual boundary 9 is formed by following the outer surface of the primary conductors 6 and interconnecting (virtual interconnection) these primary conductors 6 via the shortest distance (straight virtual lines). Thus, the star point 8 can be arranged anywhere within the outer boundaries defined by the virtual boundary 9 shown.

[0102] In this embodiment, as a special example arranged within the outer boundary, Figure 1 As shown, since the star plates 14 and 15 are symmetrical, the star point 8 of the secondary conductor 7 corresponds to the geometric center of the star plates 14 and 15. In this embodiment, the star point 8 of the secondary conductor 7 is arranged at the center position 11 of the transformer 1 between the legs 4. In other words, in this embodiment, the star point 8 coincides with the geometric center of the legs 4 and / or the primary conductor 6. Now we will refer again to Figure 3 Explain this.

[0103] It can be concluded that the center position 11 is defined by the respective midpoints 16 of all virtual lines 17 spanning the shortest distance between the separated legs 4 of at least one core component 2. The center position 11 is obtained by projecting all the midpoints 16 to a common point. In the present embodiment with three legs 4, a midpoint 16 is defined between the first leg 4 and the second leg 4 (e.g., top and right), another midpoint 16 is defined between the second leg 4 and the third leg 4 (right and left), and yet another midpoint 16 is defined between the first leg 4 and the third leg 4 (top and left). The center position 11 is then a combined projection of the above midpoints 16, such as the center of a triangle defined by the three virtual lines 17 spanning between the three legs 4.

[0104] Alternatively, the center position 11 may be defined by at least one virtual line 17, for example one or two or (in the case of more than three legs 4) four or more. Thus, the center position 11 is obtained by defining the middle points 16 between the legs 4 and projecting these middle points 16 to a common center.

[0105] Typically, the center position 11 can be defined by a tolerance range, which can be defined as 20% of the distance between the legs 4 (i.e., the length of the one or more virtual lines 17), preferably 10%, more preferably 5% or 2% or less.

[0106] So far, Figure 1 and Figure 3 The positioning of the star point 8 is explained with respect to the plan view of the transformer 1. Figure 2 As shown, in a cross-sectional view or a side view perpendicular to the plan view, the star point 8 is also within the outer boundary of the transformer 1. It can be clearly seen from this that in the side view, the star point 8 is not necessarily located at the center position 20 of the transformer 1, that is, its center position 20 relative to the height of the transformer 1. However, there are such embodiments of the present invention: in which the star point 8 is additionally or alternatively located at the center position 20 of the transformer 1 relative to the height of the transformer 1, in particular relative to the height of the leg 4. Here, the term "height" refers to the dimension in the direction 5 of the leg extension. In other words, in this embodiment, the star point 8 of the secondary conductor 7 is not at the center position 20 of the transformer 1 in the direction 5 of the leg extension.

[0107] Figure 4 FIG. 1 shows a reluctance model diagram of a multiphase transformer 1 according to a first embodiment. The reluctance model diagram shown provides Figure 1 and Figure 2 A brief description of the electromagnetic characteristics of the transformer 1 is shown.

[0108] Among them, "i s1 ", "i s2” and “i s3 " indicates that the flow through the corresponding first ("i s1 ”) to the third (“i s3 ”) The secondary current of the secondary conductor 7. “R m,g " represents the magnetic resistance of each leg portion 4. "N p i p1 ","N p i p2 ” and “N p i p3 " respectively indicates the number of turns flowing through is "N p "The corresponding first ("N p i p1 ”) to the third (“N p i p3 ”)The primary current of the primary conductor 6.

[0109] from Figure 4 It can be seen from the shown reluctance model that the transformer 1 is composed of a magnetic star-delta transformer.

[0110] Figure 5 A schematic cross-sectional view of a multiphase transformer 1 according to a second embodiment of the invention is shown.

[0111] Here, the transformer 1 includes the same number of primary conductors 6 as in the first embodiment. However, each primary conductor 6 includes a plurality of primary conductor portions 10. In other words, each primary conductor 6 of each corresponding leg portion 4 includes a plurality of primary conductor portions 10 along the leg extension direction 5, and each primary conductor portion 10 has at least one turn. Therefore, the transformer 1 includes a total of nine primary conductor portions 10 (three primary conductors 6 each have three primary conductor portions 10, i.e., three leg portions 4 each have three primary conductor portions 10). Figure 5 Six of them are shown in FIG.

[0112] In particular, the primary conductor portions 10 of one primary conductor 6 (ie, one leg portion 4 ) are electrically connected to each other so as to collectively define one primary conductor 6 (one primary-side winding).

[0113] Furthermore, the transformer 1 comprises a plurality of star plates 14, 15 ( Figure 1 ). The star plates 14, 15 are stacked alternately with the primary conductor parts 10. Figure 5 In the figure, due to the cross-sectional side view, only one extension 14 of the corresponding plate 14, 15 is shown. These extensions 14, in particular their secondary connection points 18 (with Figure 1), are connected to each other via a connecting conductor 19. In this embodiment, the connecting conductor 19 is also plate-shaped. Although not shown due to the cross-sectional side view, the transformer 1 includes three such connecting conductors 19, that is, there is one connecting conductor 19 for each group of extensions 14.

[0114] The connecting conductor 19 preferably connects only the extending portions 14 that overlap each other in a plan view. Figure 1 In the view of FIG. 1 , for the extensions 14 of all the star-shaped plates 14 and 15, one connecting conductor 19 connects all the upper right extensions 14, another connecting conductor 19 connects all the upper left extensions 14, and another connecting conductor 19 connects all the lower middle extensions 14. Therefore, in this embodiment, the transformer 1 includes the following Figure 5 Shown are three such connecting conductors 19. In particular, the connecting conductors 19 are bus bars.

[0115] Preferably, the connecting conductor 19 is formed by extending and bending the extensions 14 and connecting them to each other. For example, the connecting conductor 19 is formed integrally with one extension 14 and connected to at least one other extension 14 of another star plate 14, 15. In the case where each extension 14 is bent to define one connecting conductor 19 connected to the next star plate 14, 15 along the leg extension direction 5 (stack direction), the transformer 1 of the present embodiment includes three such connecting conductors 19 for each (shown) side view, with a total of nine connecting conductors 19. Among them, the extension 14 of the topmost star plate 14, 15 is bent downward (opposite to the leg extension direction 5 shown) and connected to the extension 14 of the star plate 14, 15 next to the topmost, and so on. Such a connecting conductor 19 may also preferably extend on a plurality of star plates 14, 15 along the leg extension direction 5 shown or opposite to the leg extension direction 5 shown for their interconnection.

[0116] Thus, by increasing the number of star plates 14 , 15 , the number of turns of the secondary conductor 7 can advantageously be increased, in particular according to an advantageously predetermined turns ratio of the transformer 1 .

[0117] The present invention also relates to an LLC resonant converter 100 . Figure 6 A circuit diagram of an LLC resonant converter 100 including a multi-phase transformer 1 according to the present invention is shown.

[0118] The LLC resonant converter 100 (hereinafter referred to as the "converter 100") includes the multi-phase transformer 1 according to the aforementioned embodiment. Figure 6 It can be seen that the primary conductors 6 are connected in a delta configuration. Furthermore, the secondary conductors 7 are connected in a star configuration at their secondary connection points 18.

[0119] In this embodiment, the converter 100 is a three-phase converter.

[0120] In particular, since the star point 8 of the secondary side is arranged within the transformer 1, i.e. within a virtual boundary 9 defined by the outer boundaries of at least one core component 2 and / or the primary conductor 6, such as for example in Figure 1 As shown in , the winding length on the secondary side can be reduced. In addition, the secondary conductor 7 generates an integrated stray field, which is used as the resonant inductance of the converter 100. Therefore, the converter 100 (specifically its resonant cavity) does not require a discrete or separate resonant inductor, thereby increasing the power density of the system.

[0121] In addition to the above written instructions, explicit reference to Figures 1 to 6 , wherein these figures show in detail the circuit diagram and configuration examples of the present invention.

Claims

1. A multiphase transformer (1), comprising: At least one magnetic core component (2), comprising a main body portion (3) and a plurality of leg portions (4) extending from the main body portion (3) along a leg extension direction (5); A primary side having a plurality of primary conductors (6), wherein each of the primary conductors (6) is wound around a leg portion (4); as well as A secondary side having a plurality of secondary conductors (7), each of which at least partially surrounds a leg portion (4), the secondary conductors (7) being interconnected in an electrical star configuration; wherein the primary conductor (6) and the secondary conductor (7) are stacked along the leg extension direction (5), and The secondary-side star point (8) is arranged at least geometrically at a position within a virtual boundary (9) defined by the outer boundaries of the at least one magnetic core component (2) and / or the primary conductor (6).

2. The multiphase transformer (1) according to claim 1, wherein the star point (8) of the secondary conductor (7) is located at least geometrically at a central position (11) of the transformer (1) between the legs (4).

3. The multiphase transformer (1) according to claim 2, wherein the secondary side comprises at least one plate (14, 15), wherein portions of the plate (14, 15) respectively define the secondary conductor (7).

4. A multiphase transformer (1) according to claim 3, wherein each of said secondary conductors (7) is defined as a portion of said at least one plate (14, 15) adjacent to a respective leg portion (4) of said at least one core member (2).

5. The multiphase transformer (1) according to claim 4, wherein the geometrical center of the at least one plate (14, 15) corresponds to the star point (8) of the secondary conductor (7).

6. The multiphase transformer (1) according to claim 3, wherein the at least one plate (14, 15) is star-shaped.

7. The multiphase transformer (1) according to claim 6, wherein each star plate (14, 15) comprises a middle part (15) and a plurality of extension parts (14), the extension parts (14) extending from the middle part (15), wherein the star point (8) of the secondary conductor (7) is located in the middle part (15).

8. The multiphase transformer (1) according to claim 1, wherein the primary conductor (6) is a wire.

9. The multiphase transformer (1) according to claim 1, wherein the primary conductors (6) and the secondary conductors (7) are alternately stacked.

10. The multiphase transformer (1) according to claim 9, wherein each of the plurality of primary conductors (6) comprises a plurality of primary conductor portions (10) in the leg extension direction (5) along the corresponding leg portion (4), each of the primary conductor portions (10) comprising at least one turn around the corresponding leg portion (4), and wherein at least two of the primary conductor portions (10) sandwich a secondary conductor (7).

11. The multiphase transformer (1) according to claim 1, wherein the multiphase transformer (1) comprises three phases, wherein the at least one magnetic core component (2) comprises three leg portions (4), and the three leg portions (4) are arranged in a triangular arrangement along their extension direction (5) from a plan view.

12. The multiphase transformer (1) according to claim 7, wherein the multiphase transformer (1) comprises three phases, the at least one magnetic core component (2) comprises three leg portions (4), the three leg portions (4) are arranged in a triangular arrangement along their extension direction (5) from a plan view, each of the star-shaped plates (14, 15) comprises a triangular middle portion (15) and three extension portions (14), each of the extension portions (14) being arranged between two adjacent leg portions (4).

13. The multiphase transformer (1) according to claim 1, wherein the primary conductors (6) are connected in an electrical delta configuration.

14. An LLC resonant converter (100) comprising a multiphase transformer (1) according to any one of the preceding claims.

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