Controllable transformer and method for controlling a transformer
Patent Information
- Application Number
- EP2024703272
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-01-27
- Filing Date
- 2024-01-25
- Publication Date
- 2025-12-03
AI Technical Summary
Transformers face challenges in adaptability due to slow switching times and wear-related issues with mechanical adjustments for varying magnetization inductance and voltage transformation ratios, especially in power grids with renewable energy integration and clocked power supplies.
A controllable transformer design with a control section featuring strategically arranged bores for a control winding, allowing for fast and fail-safe adjustment of magnetization inductance, leakage inductance, and voltage transformation ratio using a direct current, which integrates a modified virtual air gap concept for complex bias magnetization patterns.
Enables monotonic and approximately linear variation of magnetization inductance over a wide range, reducing wear and increasing adaptability and reliability, with the ability to set constant magnetization inductance across the operating range.
Smart Images
Figure EP2024051793_02082024_PF_FP
Abstract
Description
[0001] CONTROLLED TRANSFORMER AND METHOD FOR CONTROLLING A TRANSFORMER
[0002] The present invention relates to a controllable transformer and a method for controlling a transformer.
[0003] STATE OF THE ART
[0004] Transformers are among the most common components in electrical engineering and are used for voltage conversion, for example, in power supply systems, in the power supplies of technical devices, as well as in signal transmission and protective isolation. A transformer can be designed in single-phase or multi-phase configurations and typically consists of at least two coils, commonly referred to as the primary winding and the secondary winding, which are wound as insulated conductors around a magnetic transformer core. The transformer core is made, in particular, of a soft magnetic material in solid or laminated form, for example in the form of ferrous materials, sintered ferrites, electrical steel, or composite materials.The electrical voltages at the windings are converted via the ratio of the number of turns, which is usually divided into primary voltage U1 with the number of turns N1 and secondary voltage U2 with the number of turns N2. Ideally, this results in a voltage conversion ratio of U1 / U2 = N1 / N2.
[0005] The transformation of power grids resulting from the expansion of renewable energies is creating increasing demands for transformers to be adaptable to changing operating conditions in order to ensure maximum power consumption and grid stability throughout. Furthermore, switch-mode power supplies (power electronics) are increasingly being used for efficient and resource-saving energy conversion, and these systems also require controllable transformers, allowing, in particular, the voltage transformation ratio, magnetizing inductance, or leakage inductance to be specifically varied.
[0006] In the prior art, it is known to variably stage the voltage transformation ratio of transformers by means of switchable winding taps.
[0007] Unfortunately, such a tap changeover poses great challenges to the required switching elements and results in significant compensating currents and transient factors influencing the transformer operation.
[0008] To vary the magnetizing inductance of a transformer or a choke coil, it is also known to vary the length of an air gap in the transformer or coil core, for which purpose a core segment is designed to be mechanically movable. The disadvantage of this concept is the slow switching times caused by the mechanical actuation, which typically last in seconds. The movable core segment is also a wear part, particularly due to the vibrations caused by electromechanical forces that occur in typical application environments. This susceptibility to wear limits the service life of the transformers and also creates a risk of failure.
[0009] An alternative is the so-called virtual air gap concept, which is disclosed, for example, in the document EP 2 686 931 B1 for a choke coil. The virtual air gap concept is based on an adjustable pre-magnetization of a magnetic core by means of an energizable control winding which extends through bores in a core section. When the control winding is energized by a control current, a magnetic flux is introduced around the bores in the core section, which can influence the magnetizing inductance. In contrast to a core with a mechanically variable air gap length, however, the variation in the magnetizing inductance is highly dependent on the respective operating point of the choke coil, i.e. it is not possible to set a magnetizing inductance that is constant over the entire operating range, which is unsatisfactory from a control engineering perspective.
[0010] DISCLOSURE OF THE INVENTION
[0011] It is the object of the present invention to propose a controllable transformer and an associated method for controlling a transformer, which are based in particular on a fast, fail-safe and demand-based adaptability of the magnetizing inductance, the leakage inductance and / or the voltage transformation ratio of the transformer.
[0012] This object is achieved based on a controllable transformer according to claim 1 and a method according to claim 20. Advantageous developments of the invention are specified in the dependent claims.
[0013] The technical teaching of the invention discloses a controllable transformer, at least comprising a primary winding, a secondary winding and a magnetic transformer core, wherein the transformer core has at least one control section with at least three bores, wherein the control section has a longitudinal extension direction corresponding to the main magnetic flux direction, a first transverse extension direction and a second transverse extension direction, wherein the three extension directions are oriented perpendicular to each other in pairs, and wherein
[0014] - the holes run essentially along the second transverse direction,
[0015] - in each transverse extension plane of the control section, which is spanned by the first transverse extension direction and the second transverse extension direction, at most one bore extends, and
[0016] - a distance of at least one bore to one of the two nearest outer edges of the control section in the first transverse direction of extent is greater than o a distance of the bore to a further edge of the control section, and / or o half a distance to a further bore, wherein a control winding runs through the bores in such a way that a premagnetization of the control section can be generated by means of a control current through the control winding.
[0017] The invention is based on the idea of integrating a controllable reluctance into the magnetic circuit of the transformer using the control section. This involves a modification of the virtual air gap concept, which affects the number of holes for accommodating the control winding and their arrangement relative to one another and to the edge of the control section. This enables the setting of complex premagnetization patterns in the control section of the transformer core, the usefulness of which for controlling the transformer will be demonstrated in detail later. In particular, the inventive concept makes it possible to vary the magnetizing inductance of the transformer essentially monotonically and approximately linearly over a wide operating range using the control current, in particular using a direct current.Depending on the relative arrangement of the control section, primary winding and secondary winding, a variation of the magnetizing inductance, the leakage inductance or the voltage transformation ratio is the focus of the control of the transformer according to the invention.
[0018] Figures 1a to 1c initially serve to illustrate the arrangement of the bores in the control section as part of the transformer core according to the invention. These show schematic views of a control section 31, through which one or two bores 4 run. The control section 31 has a longitudinal direction of extent Z, which corresponds to the local main magnetic flux direction, and a transverse extension plane which is orthogonal to the longitudinal direction of extent Z and is spanned by the first transverse direction of extent X and the second transverse direction of extent Y. The bores 4 run essentially along the second transverse direction of extent Y, with at most one bore 4 running in each transverse extension plane. According to the invention, the distance x1 of a bore 4 to one of the two nearest outer edges of the control section 31 in the first transverse direction of extent X is greater than a distance x2 ora distance z1 of the bore 4 to a further edge of the control section 31 (Figures 1 a and 1 b), or the distance x1 is greater than half the distance d4 to a further bore 4 (Figure 1 c).
[0019] In the context of the present application, the main magnetic flux direction is to be understood as the local main flux direction in a respective transformer core segment, as illustrated in Figure 2. This shows, by way of example, a U-shaped section of a transformer core 3 which comprises one horizontal and two vertical segments, the transitions between which are represented by the dashed boundary lines. Along with the different main flux directions of the magnetic flux ', C>", 0'" in the three transformer core segments, the longitudinal extension direction Z', Z", Z"' and the transverse extension directions X', X", X"' and Y', Y", Y"' are also oriented differently locally within the meaning of the present application, wherein the provisions according to the invention regarding the arrangement of the bores in the control section relate to the respectively locally valid coordinate system X, Y, Z of the respective transformer core segment.
[0020] Furthermore, Figures 3a to 3c show schematic views of a control section 31 with bores 4 arranged according to the invention, through which the control winding 5 runs, which in the case of Figure 5a passes through each bore 4 only once and in the case of Figures 5b and 5c passes through each bore 4 multiple times. In the latter case, a higher control current is generated by the control current, or a lower control current is required to generate an identical control current. Within the scope of the present invention, different winding concepts of the control winding can be used to expediently influence the premagnetization of the control section of the transformer core.
[0021] To illustrate the basic idea of the present invention, simulated distributions of the magnetic flux density in rod-shaped control sections 31 of soft magnetic transformer cores are shown in Figures 4, 5, 6 and 7a as field line images, which result when the control winding is energized with different arrangements of the bores 4. The left-hand partial image in each case shows a schematic representation of the underlying model, i.e. the position of the bores 4 in the control section 31, wherein the position is systematically varied in each case, on which the distributions of the magnetic flux density shown in the further partial images are each based. The simulation is based on a fixed control magnetic flux through the bores 4, wherein the primary and secondary windings of the associated transformer are each de-energized. The sign of the control magnetic flux of each bore 4 is represented by a dot or cross symbol.
[0022] In Figure 4, a systematic variation of the distance between the holes 4 and the outer edges of the control section 31 in the first transverse direction of extent X, i.e., a variation of the ratio x2 / x1, is performed. With a central arrangement of the holes 4, i.e., with x2 / x1 = 1, a symmetrical flux density distribution results, which corresponds to a corresponding distribution of the premagnetization of the control section 31. With a sufficiently high control current, the premagnetization in the extension planes of the two holes 4 is driven completely into saturation, so that the control section 31 is not able to absorb any further magnetic flux from energizing a primary winding and thus the magnetization inductance of the transformer is reduced. This exclusively central arrangement of the holes 4 corresponds to the virtual air gap concept according to the prior art. With a displacement of the holes 4 in the first transverse direction of extent X, i.e., with a reduction in the ratio x2 / x1, an asymmetric distribution of magnetic flux density and pre-magnetization of the control section 31 develops in the transverse extension planes XY. With these off-center arrangements of the bores 4, it is practically impossible to generate complete saturation of the pre-magnetization in the entire transverse extension plane of the respective bore 4 using the control current, since due to the source-free nature of the magnetic flux density, the bottleneck defined by the distance x2 limits the magnetic flux. Thus, at x2 / x1 = 0.33, the flux density introduced into the control section 31 is already significantly lower than, for example, at x2 / x1 = 1, and in the extreme case x2=0 (of little relevance in practice), (almost) no magnetic flux is introduced into the control section 31 given the underlying control magnetic flux through the bores 4.
[0023] Figure 5 shows the flux distributions when the ratio of length Bz to width Bx of the control section 31 varies, i.e., when the ratio z1 / x1 varies. In arrangements with z1 / x2 < 1, the distance z1 between the bore 4 and the outer edge of the control section 31 represents a bottleneck that limits the magnetic flux, so that in these arrangements it is practically impossible to generate complete saturation of the premagnetization of the control section 31 in the transverse extension plane XY of the bore 4 using the control current. Figure 6 shows the distribution of the magnetic flux density in the control section 31 when the distance ratio x2 / x1 of the bores 4 to the outer edges of the control section 31 varies in the first transverse extension direction X, wherein the bores 4 are offset in opposite directions and have a control magnetic flux in the same direction.In comparison to the example of Figure 4, similar flux distributions result in the transverse extension planes of the bores 4, whereas the area between the bores 4 is differently pre-magnetized due to the differences in the orientation of the control magnetic flux.
[0024] Figure 7a shows the distributions of the magnetic flux density in the control section 31 while varying the distance d4 in the longitudinal direction Z between the two oppositely flowing bores 4. In the area between the bores 4, there is a constructive superposition of the partial magnetic fluxes, so that the control section 31 is first transferred into a state of completely saturated premagnetization there, which again results in a limitation of the magnetic flux in the respective transverse planes XY of the bores 4, so that essentially no complete saturation of the premagnetization can be generated there by means of the control current.
[0025] Figure 7b shows characteristic curves of the magnetic flux (in units of the saturation flux sat) in the control section corresponding to the simulations in Figure 7a as a function of a magnetic voltage V, which is generated by energizing a primary winding of the transformer wound around the control section, with a constant control magnetic flux Hs of the control winding and varying the d4 / x1 ratio as shown in Figure 7a. At d4 / x1 = 0, i.e., with an arrangement of the holes by means of which practically no magnetic flux can be introduced into the control section via a control current, the characteristic curve O(V) corresponds to a conventional coil with a soft magnetic core. When the d4 / x1 ratio is increased, i.e., in the presence of a premagnetization of the control section caused by the control magnetic flux Hs, the characteristic curves (V) have characteristic plateaus which reflect magnetization reversal processes of the premagnetization due to the applied magnetic voltage V. Depending on the specific arrangement of the holes, the premagnetization is expressed to varying degrees, so that the position of the plateaus in the (V) characteristic curves varies. An essential aspect of the present invention is based on this finding, namely a practical embodiment, ie, in particular a linearization of the O(V) characteristic curves by means of a combination of holes in different arrangements for the premagnetization of the control section of the transformer core which can be expressed differently in each section.
[0026] This is shown by way of example in Figure 8a, in which the results of a simulation of the distribution of the magnetic flux density and the resulting (V) characteristic curve are shown based on a control section 31 with three pairs of bores 4, wherein the pairs have different distances d4 in the longitudinal direction Z between the associated bores 4. In the (V) characteristic curves when a control current Is is applied as a direct current, a plurality of steps are shown corresponding to the magnetization reversal processes around the individual bores 4, and an increase in the control current Is results in a tilting of the characteristic curves.
[0027] Figure 8b shows the corresponding characteristics of the flux linkage T in the control section and the magnetizing inductance L of the transformer versus the current I through the primary winding, with the primary winding wound around the control section and the secondary winding de-energized. This shows the desired characteristic, which approximately corresponds to the behavior of a coil with a coil core with a mechanically variable air gap width, i.e., a magnetizing inductance L that is approximately constant over the entire operating range and can be varied monotonically and approximately linearly (power function with an exponent between 1 and 2) over a wide range of values by means of the control current Is. A particular advantage of the invention is that only a direct current is required as the control current Is to control the magnetizing inductance of the transformer.
[0028] For example, the control section of the transformer according to the invention has at least one air gap extending in a transverse plane of the control section, wherein the air gap forms a boundary of the control section. The control section can thus be formed from a plurality of segments separated by air gaps. The provision of air gaps serves to "statically" influence the magnetizing inductance of the transformer.
[0029] As already illustrated by way of example in Figure 8a, the control section has, for example, a plurality of pairs of bores, wherein the pairs have different distances between the associated bores. Furthermore, the bores can, for example, have different distances from an outer edge of the control section in the first transverse direction. This creates differently dimensioned constrictions for the magnetic flux in the transverse planes of the bores, resulting in the desired quasi-linearization of the magnetic flux characteristic curves as a function of the magnetic voltage.
[0030] For example, at least one of the holes can be designed as an elongated hole. An elongated hole can accommodate a larger number of turns of the control winding, allowing for a higher control current flow.
[0031] In a specific embodiment, the control section has a plurality of control section segments which are separated from one another by air gaps, wherein each control section segment has at least one bore, wherein the control section segments have in particular different dimensions in the longitudinal direction relative to the dimension in the first transverse direction.
[0032] For example, at least one primary winding and / or at least one secondary winding are wound around the control section of the transformer core. Alternatively, a transformer according to the invention can be designed such that neither a primary winding nor a secondary winding is wound around the control section of the transformer core. In the latter embodiment, the degree of coupling between the primary and secondary windings can be influenced by the control current.
[0033] Furthermore, the transformer according to the invention can be designed as a multi-phase transformer, wherein the transformer comprises a plurality of control sections, each assigned to a phase of a multi-phase alternating current. For example, the transformer according to the invention comprises a direct current source and an associated controller, by means of which the control current for generating the premagnetization of the control section can be introduced into the control winding.
[0034] The invention further relates to a method for controlling a transformer according to one of the aforementioned embodiments, wherein a control current is introduced into the control winding, which generates a bias in the control section of the transformer core such that a desired magnetizing inductance of the transformer and / or a desired voltage transformation ratio between the at least one primary winding and the at least one secondary winding is set. The control current is generated, for example, by a direct current source.
[0035] In one embodiment of the method, a current flowing through a primary winding of the transformer is embodied as a pulsed direct current, which, after passing through the primary winding, passes through the control winding, thereby forming the control current. The pulsed direct current has a direct current and an alternating current component, wherein the alternating current component is preferably significantly smaller than the direct current component, for example, being one-third of the direct current component. In this embodiment, the magnetizing inductance of the transformer is therefore determined by the current carried in the primary winding.
[0036] If the current flowing through the primary winding is a mixed current, the direct current component and the alternating current component of the mixed current can be separated from one another within the scope of the method according to the invention, with the control current being formed by the direct current component. The separation into direct current and alternating current components can be carried out, for example, by means of a primary winding which comprises two parallel windings, one of which is formed from a stranded wire bundle and the other from a low-resistance solid wire or another solid conductor, e.g. with a rectangular profile, so that the alternating current component flows through the stranded wire bundle and the direct current component through the solid conductor, with the direct current component then passing through the control winding as the control current.
[0037] Within the scope of the method according to the invention, the control current can also be formed from a combination of a component supplied by a direct current source and a component from the current to be limited. For this purpose, two separate control windings can be provided, for example.
[0038] EMBODIMENTS OF THE INVENTION
[0039] Further measures improving the invention are presented in more detail below with the description of embodiments of the invention with reference to figures.
[0040] Figures 9, 10a, 11, 12, 13a, 14, 15, 16a, 17, 18, 19 and 20a show different embodiments of transformers 100 according to the invention in a schematic cross-sectional view. For the sake of clarity, the control windings are not shown in the figures. According to the previous description, the control windings each run through the bores 4 in the control section 31. The arrangement of the bores 4 corresponds in each case to the technical teaching of claim 1. With the exception of the embodiment in Figure 17, the transformer cores 3 shown have sections referred to as legs, which run vertically in the figures, and sections referred to as yokes, which run horizontally. The entirety of legs and yokes forms the transformer core and thus the magnetic circuit.
[0041] Figure 9 shows a transformer 100 with a transformer core 3, which has two legs and two yokes (structure made up of two U-cores), wherein the yoke at the top in the illustration forms the control section 31 with six bores 4. The longitudinal extension direction Z of the control section 31 corresponds to the main magnetic flux direction through the yoke, and the bores 4 run perpendicular to the image plane of Figure 9, i.e. perpendicular to the first transverse extension direction X and to the longitudinal extension direction Z. The primary winding 1 and the secondary winding 2 are each wound here, for example, around a leg of the transformer core 3.
[0042] Figure 10a shows a transformer 100, the transformer core 3 of which is designed as a three-leg core with a center leg, a first outer leg (left) and a second outer leg (right), wherein the center leg forms the control section 31 with the bores 4, wherein a primary winding 1 is wound around the center leg and the second outer leg, and wherein a secondary winding 2 is wound around the second outer leg.
[0043] Figure 10b shows simulated distributions of the magnetic flux density in the transformer core 3 of a transformer according to the embodiment of Figure 10a, wherein the primary winding 1 is energized and the secondary winding 2 is de-energized, and wherein a different control current Is flows through the control winding in the bores of the control section (center leg) in each sub-image. In the left-hand sub-image, the control winding is de-energized and the magnetic flux of the primary winding 1 can essentially pass freely through the center leg. In the middle sub-image, the control current Is is selected to be large enough to pre-magnetize the center leg, but without the magnetization becoming locally saturated. The magnetic flux of the primary winding 1 can therefore still pass through the center leg to a limited extent.In the right-hand part of the image, however, the control current Is leads to a local saturation of the magnetization of the center leg in the area of the holes, so that the magnetic flux of the primary winding 1 cannot be absorbed in the center leg. With increasing control current Is, i.e., with increasing premagnetization of the center leg forming the control section, the magnetic flux of the primary winding 1 is increasingly conducted through the second outer leg and thus through the secondary winding 2.
[0044] For the embodiment of Figure 10a, Figure 10c shows the associated voltage transformation ratio, ie, the quotient of primary winding voltage U1 to induced secondary winding voltage U2, as a function of the control current Is. Due to the inventive arrangement of the holes in the control section that accommodate the control winding, a characteristic that is suitable for the purpose of control and at least partially linear is present.
[0045] Figure 11 shows a transformer 100 whose transformer core 3 is designed as a three-leg core with a center leg, a first outer leg, and a second outer leg, the center leg forming the control section 31, a primary winding 1 being wound around the center leg and the second outer leg, a first secondary winding 2a being wound around the second outer leg, and a second secondary winding 2b being wound around the center leg. Figure 12 shows a transformer 100 whose transformer core 3 is designed as a three-leg core with a center leg, a first outer leg, and a second outer leg, the center leg forming the control section 31, a primary winding 1 being wound around the first outer leg, and a secondary winding 2 being wound around the center leg.
[0046] Figure 13a shows a transformer 100 whose transformer core 3 is designed as a shell core with a center leg, the center leg forming the control section 31, with a primary winding 1 and a secondary winding 2 wound around the center leg. A corresponding equivalent circuit diagram is shown in Figure 13b. The bias of the control section 31 can be controlled by means of the control current, resulting in a variable magnetizing inductance Lvar parallel to the main inductance LH, and thus the magnetizing current of the transformer 100 can be controlled.
[0047] Figures 14 and 15 show two further embodiments of transformers 100 according to the invention in a shell-core design, in which air gaps 30 extending in a transverse extension plane of the control section 31 lead to a reduction in the magnetization inductance. In Figure 15, the control section 31 has a plurality of control section segments separated from one another by air gaps 30, each control section segment having a bore 4, the control section segments partially having different dimensions in the longitudinal extension direction Z relative to the dimension in the first transverse extension direction X. The bore 4 in the middle segment is designed as an elongated hole, which enables a higher control flux.Figure 16a shows a transformer 100 whose transformer core 3 is designed as a three-leg core with a center leg, a first outer leg, and a second outer leg, the second outer leg forming the control section 31, a primary winding 1 being wound around the first outer leg, and a secondary winding 2 being wound around the center leg. Figure 16b shows a corresponding equivalent circuit diagram. In this configuration, the variation of the premagnetization of the control section 31 by means of a control current primarily serves to control the coupling between the primary winding 1 and the secondary winding 2. In a further embodiment, not shown here, the control section 31 can have an additional air gap in order to increase the coupling of the primary winding 1 and the secondary winding 2 in the state not premagnetized by a control current or to set it to a starting value.
[0048] In the embodiment of Figure 17, the transformer core 3 is ring-shaped, wherein the entire transformer core 3 forms the control section 31, and wherein the bores 4 extend in the radial direction as a second transverse extension direction Y', Y" through the control section 31. The main flow direction of the magnetic flux, corresponding to the local longitudinal extension direction Z of the control section 31, is circular here.
[0049] Figure 18 shows a transformer 100, the transformer core 3 of which is designed as a shell core with a center leg and a center yoke, the center yoke forming the control section 31, with a two-part primary winding 1.1, 1.2 and a two-part secondary winding 2.1, 2.2 wound around the center leg. The transformer 100 in the embodiment of Figure 19 is three-phase, with the transformer core 3 being designed as a six-leg core, with the first leg, the third leg, and the fifth leg each forming a control section 31.p1, 31.p2, 31.p3,
[0050] - a primary winding 1 ,p1 of the first phase is wound around the first leg and the second leg, and a secondary winding 2.p1 of the first phase is wound around the second leg, and
[0051] - a primary winding 1 ,p2 of the second phase is wound around the third leg and the fourth leg, and a secondary winding 2.p2 of the second phase is wound around the fourth leg, and
[0052] - a primary winding 1,p3 of the third phase is wound around the fifth leg and the sixth leg, and a secondary winding 2,p3 of the third phase is wound around the sixth leg.
[0053] Figure 20a shows a transformer 100 with a transformer core 3 made of a combination of a shell core section (bottom) and an E-core section (top) arranged thereon, wherein the center leg of the E-core section forms the control section 31 and is separated from the shell core section by an air gap 30, wherein a first partial winding 1.1 of the primary winding is wound around the control section 31, and wherein a second partial winding 1.2 of the primary winding and a secondary winding 2 are wound around the center leg of the shell core section. Figure 20b shows an associated equivalent circuit diagram, from which it can be seen that in this exemplary embodiment, by means of the control current and the resulting premagnetization in the control section 31, in particular the leakage inductance L aiThe primary winding is variable. The invention is not limited in its implementation to the preferred embodiments specified above. Rather, a number of variants are conceivable, which utilize the presented solution even in fundamentally different embodiments. All features and / or advantages apparent from the claims, the description, or the drawings, including design details or spatial arrangements, can be essential to the invention both individually and in a wide variety of combinations.
[0054] List of characters:
[0055] Fig. 1 a - 1 c: schematic representations of the arrangement of the bores according to the invention,
[0056] Fig. 2: schematic diagram to illustrate the
[0057] Directional signs,
[0058] Fig. 3a - 3c: schematic representations of the control windings according to the invention,
[0059] Fig. 4: simulated flux density distributions in a control section with variation of the bore arrangement,
[0060] Fig. 5: simulated flux density distributions in a control section with variation of the geometry,
[0061] Fig. 6: simulated flux density distributions in a control section with variation of the bore arrangement,
[0062] Fig. 7a: simulated flux density distributions in a control section with variation of the bore arrangement,
[0063] Fig. 7b: Characteristic curves for Fig. 7a,
[0064] Fig. 8a: simulated flux density distributions in a control section with variation of the bore arrangement and corresponding characteristic curves,
[0065] Fig. 8b: Characteristic curves for Fig. 8a,
[0066] Fig. 9 first embodiment of a transformer according to the invention,
[0067] Fig. 10a: second embodiment of a transformer according to the invention,
[0068] Fig. 10b simulated flux density distributions in the transformer of Fig. 10a when varying the control current,
[0069] Fig. 10c Characteristic curve of the transformer of Fig. 10a,
[0070] Fig. 11 : third embodiment of an inventive
[0071] Transformer, Fig. 12: fourth embodiment of an inventive
[0072] transformer,
[0073] Fig. 13a: fifth embodiment of a transformer according to the invention,
[0074] Fig. 13b Equivalent circuit of the transformer of Fig. 13a,
[0075] Fig. 14: sixth embodiment of an inventive
[0076] transformer,
[0077] Fig. 15: seventh embodiment of an inventive
[0078] transformer,
[0079] Fig. 16a: eighth embodiment of a transformer according to the invention,
[0080] Fig. 16b: Equivalent circuit of the transformer of Fig. 16a,
[0081] Fig. 17: ninth embodiment of an inventive
[0082] transformer,
[0083] Fig. 18 tenth embodiment of a transformer according to the invention,
[0084] Fig. 19: Eleventh embodiment of an inventive
[0085] transformer,
[0086] Fig. 20a: twelve embodiments of a transformer according to the invention, and
[0087] Fig. 20b: Equivalent circuit of the transformer in Fig. 20a.
[0088] List of reference symbols:
[0089] 100 transformer
[0090] 1 primary winding
[0091] 1.1 , 1.2 Partial winding of a primary winding
[0092] 1.p1 , 1.p2, 1.p3 phase of a primary winding
[0093] 2, 2a, 2b secondary winding
[0094] 2.1 , 2.2 Partial winding of a secondary winding
[0095] 2.p1 , 2.p2, 2.p3 phase of a secondary winding
[0096] 3 transformer core
[0097] 30 air gap
[0098] 31 Tax Section
[0099] 4 Hole Control winding
[0100] X first transverse direction
[0101] Y second transverse direction
[0102] Z Longitudinal direction x1 , x2, z1 Distance to edge d4 Distance between holes
[0103] Bx dimension transverse extension
[0104] Bz Dimension Longitudinal extension
[0105] Is control current .S control magnetic flux
[0106] T Flow linkage
[0107] V magnetic voltage Leakage inductance
[0108] Lvar variable magnetizing inductance LH main inductance
[0109] R electrical resistance
[0110] N1 , N2 number of turns
[0111] LI1 , U2 electrical voltage
Claims
Claims: 1 . Controllable transformer (100), comprising at least a primary winding (1), a secondary winding (2) and a magnetic transformer core (3), wherein the transformer core (3) has at least one control section (31) with at least three bores (4), wherein the control section (31) has a longitudinal extension direction (Z) corresponding to the main magnetic flux direction, a first transverse extension direction (X) and a second transverse extension direction (Y), wherein the three extension directions (X, Y, Z) are oriented perpendicular to each other in pairs, and wherein - the bores (4) extend substantially along the second transverse direction (Y), - in each transverse extension plane of the control section (31), which is spanned by the first transverse extension direction (X) and the second transverse extension direction (Y), at most one bore (4) runs, and - a distance (x1) of at least one bore (4) to one of the two nearest outer edges of the control section (31) in the first transverse direction of extent (X) is greater than o a distance (x2, z1) of the bore (4) to a further edge of the control section (31), and / or o half of a distance (d4) to a further bore (4), wherein a control winding (5) runs through the bores (4) in such a way that by means of a control current (Is) through the control winding (5) a premagnetization of the control section (31) can be generated.
2. T ransformator (100) according to claim 1, characterized in that the control section (31) has at least one air gap (30) which extends in a transverse extension plane of the control section (31), wherein the air gap (30) forms a border of the control section (31).
3. Transformer (100) according to claim 1 or 2, characterized in that the control section (31) has a plurality of pairs of bores (4), wherein the pairs have different distances (d4) between the associated bores (4).
4. Transformer (100) according to one of the preceding claims, characterized in that the bores (4) have different distances (x1) to an outer edge of the control section (31) in the first transverse direction (X).
5. Transformer (100) according to one of the preceding claims, characterized in that at least one of the bores (4) is designed as an elongated hole.
6. Transformer (100) according to one of the preceding claims, characterized in that the control section (31) has a plurality of control section segments which are separated from one another by air gaps (30), wherein each control section segment has at least one bore (4), wherein the control section segments have in particular different dimensions (Bz) in the longitudinal direction (Z) relative to dimension (Bx) in the first transverse direction (X).
7. Transformer (100) according to one of the preceding claims, characterized in that at least one primary winding (1) and / or at least one secondary winding (2) are wound around the control section (31) of the transformer core (3).
8. Transformer (100) according to one of claims 1 to 6, characterized in that neither a primary winding (1) nor a secondary winding (2) is wound around the control section (31) of the transformer core (3).
9. Transformer (100) according to one of the preceding claims, characterized in that the transformer (100) is designed to be multi-phase, wherein the transformer (3) comprises a plurality of control sections (31. p1, 31. p2, 31. p3), each of which is assigned to a phase of a multi-phase alternating current.
10. T ransformer (100) according to one of claims 1 to 6, characterized in that the transformer core (3) is designed as a three-leg core with a middle leg, a first outer leg and a second outer leg, wherein the middle leg forms the control section (31), wherein a primary winding (1) is wound around the middle leg and the second outer leg, and wherein a secondary winding (2, 2a) is wound around the second outer leg.
11. T ransformer (100) according to claim 10, characterized in that a second secondary winding (2b) is wound around the center leg.
12. T ransformer (100) according to one of claims 1 to 6, characterized in that the transformer core (3) is designed as a three-leg core with a middle leg, a first outer leg and a second outer leg, wherein the middle leg forms the control section (31), wherein a primary winding (1) is wound around the first outer leg, and wherein a secondary winding (2) is wound around the middle leg.
13. T ransformer (100) according to one of claims 1 to 6, characterized in that the transformer core (3) is designed as a shell core with a central leg, wherein the central leg forms the control section (31), wherein a primary winding (1) and at least one secondary winding (2, 2a, 2b) are wound around the central leg.
14. T ransformer (100) according to one of claims 1 to 6, characterized in that the transformer core (3) is designed as a three-leg core with a middle leg, a first outer leg and a second outer leg, wherein the second outer leg forms the control section (31), wherein a primary winding (1) is wound around the first outer leg, and wherein a secondary winding (2) is wound around the middle leg.
15. T ransformer (100) according to one of claims 1 to 6, characterized in that the transformer core (3) is annular, wherein the entire transformer core (3) or a portion thereof forms the control portion (31), and wherein the bores (4) extend in the radial or axial direction through the control portion (3).
16. T ransformer (100) according to one of claims 1 to 6, characterized in that the transformer core (3) is designed as a shell core with a central leg and a central yoke, wherein the central yoke forms the control section (31), wherein at least one primary winding (1.1, 1.2) and at least one secondary winding (2.1, 2.2) are wound around the central leg.
17. T ransformator (100) according to one of claims 1 to 6, characterized in that the transformer (100) is designed to be three-phase, wherein the transformer core (3) is designed as a six-leg core, wherein the first leg, the third leg and the fifth leg each form a control section (31.p1, 31.p2, 31.p3), wherein - a primary winding (1,p1) of the first phase is wound around the first leg and the second leg, and a secondary winding (2,p1) of the first phase is wound around the second leg, and - a primary winding (1,p2) of the second phase is wound around the third leg and the fourth leg, and a secondary winding (2,p2) of the second phase is wound around the fourth leg, and - a primary winding (1,p3) of the third phase is wound around the fifth leg and the sixth leg, and a secondary winding (2,p3) of the third phase is wound around the sixth leg.
18. Transformer (100) according to one of claims 1 to 6, characterized in that the transformer core (3) is designed as a combination of a shell core section and an E-core section arranged thereon, wherein the center leg of the E-core section forms the control section (31) and is separated from the shell core section by an air gap (30), wherein a first partial winding (1.1) of a primary winding is wound around the control section (31), and wherein a second partial winding (1.2) of the primary winding and a secondary winding (2) are wound around the center leg of the shell core section.
19. T ransformer (100) according to one of the preceding claims, characterized in that the transformer (100) comprises a direct current source and an associated control, by means of which the control current (Is) for generating the premagnetization of the control section (31) can be introduced into the control winding (5).
20. Method for controlling a transformer (100) according to one of the preceding claims, wherein a control current (Is) is introduced into the control winding (5), which generates such a premagnetization in the control section (31) of the transformer core (3) that a desired magnetization inductance of the transformer (100) and / or a desired voltage transformation ratio between the at least one primary winding (1) and at least one secondary winding (2).
21. Method according to claim 20, characterized in that the control current (Is) is generated by a direct current source.
22. Method according to claim 20, characterized in that a current (I) flowing through a primary winding (1) is designed as a pulsed direct current which, after passing through the primary winding (1), passes through the control winding (5), whereby the control current (Is) is formed.
23. Method according to claim 20, characterized in that a current (I) flowing through a primary winding (1) is designed as a mixed current, wherein the direct current component and the alternating current component of the mixed current are separated from one another, and wherein the control current (Is) is formed by the direct current component.