Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
  • H01F1/147—Alloys characterised by their composition
  • H01F1/153—Amorphous metallic alloys, e.g. glassy metals
  • H01F1/15333—Amorphous metallic alloys, e.g. glassy metals containing nanocrystallites, e.g. obtained by annealing
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F27/00—Details of transformers or inductances, in general
  • H01F27/24—Magnetic cores
  • H01F27/25—Magnetic cores made from strips or ribbons
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/001—Heat treatment of ferrous alloys containing Ni
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/002—Heat treatment of ferrous alloys containing Cr
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/005—Heat treatment of ferrous alloys containing Mn
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/007—Heat treatment of ferrous alloys containing Co
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/008—Heat treatment of ferrous alloys containing Si
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
  • C21D8/1238—Flattening; Dressing; Flexing
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
  • C21D8/125—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest with application of tension
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/005—Alloys based on nickel or cobalt with Manganese as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/07—Alloys based on nickel or cobalt based on cobalt
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
  • H01F1/147—Alloys characterised by their composition
  • H01F1/14766—Fe-Si based alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
  • H01F1/16—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of sheets
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
  • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
  • H01F41/0206—Manufacturing of magnetic cores by mechanical means
  • H01F41/0213—Manufacturing of magnetic circuits made from strip(s) or ribbon(s)
  • H01F41/022—Manufacturing of magnetic circuits made from strip(s) or ribbon(s) by winding the strips or ribbons around a coil
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
  • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
  • H01F41/0206—Manufacturing of magnetic cores by mechanical means
  • H01F41/0213—Manufacturing of magnetic circuits made from strip(s) or ribbon(s)
  • H01F41/0226—Manufacturing of magnetic circuits made from strip(s) or ribbon(s) from amorphous ribbons
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D2201/00—Treatment for obtaining particular effects
  • C21D2201/03—Amorphous or microcrystalline structure

Definitions

• Magnetic core in particular for a current transformer, and method for its production
• the invention relates to a magnetic core, in particular for a current transformer, and method for producing such a magnetic core.
• Magnet cores for current transformers, but also for power transformers and power chokes are typically provided as so-called ring band cores comprising strips of soft magnetic material.
• various production methods and the associated production devices are known.
• the known production devices are generally designed as continuous annealing plants and allow a heat treatment of rapidly solidified magnetic material (hereinafter "strip material") .
• strip material rapidly solidified magnetic material
• the more rapidly magnetized material is produced by means of a casting process and then wound into a roll, and then as a continuous strip in the continuous annealing plant During processing, the material is heat treated and simultaneously tensioned to obtain desired magnetic properties of the strip.
• Anisotropy in the strip material can be induced via the applied tensile stress so that the soft magnetic strip material produced therefrom has a pronounced flat hysteresis loop with a defined permeability ⁇ (corresponding to the induced anisotropy) along the tensile direction since the permeability level achievable with the known production method is dependent on the applied tension.
• a disadvantage of the known production method is that the provided amorphous strip material to be processed, due to the production by means of the casting process and the subsequent up and Abwicking to a coil or for processing in the continuous annealing furnace has a locally changing in the longitudinal direction of the band strip thickness.
• magnetic cores especially toroidal cores, especially if they are to be used for current transformers should be as small, light and inexpensive. These properties depend essentially on the choice of the strip material, but also on the manufacturing process used, with which the magnetic properties of the material are influenced.
• amorphous Co base alloys such as VITROVAC 6150 which have a saturation magnetization of 1
• the object of the invention is to eliminate the disadvantages of the prior art.
• a magnetic core is to be specified, which is suitable in particular for current transformers and has a low weight in comparison to the prior art. If possible, he should have a comparatively small volume and manufacture it cost-effectively. be len.
• a method for producing such a magnetic core and uses of the magnetic core are to be specified.
• the object is achieved by a magnetic core, for example for use in a current transformer, with a soft magnetic strip material of a nanocrystalline iron-based alloy having a permeability ⁇ between 1000 and 3500 and a magnetostriction less than 1 ppm.
• the magnetic core is obtainable by a method comprising providing a band-shaped material; heat-treating the band-shaped material at a heat treatment temperature; subjecting the heat-treated belt-shaped material to a tensile force in the longitudinal direction of the belt-shaped material to generate a tensile stress in the belt-shaped material, thereby obtaining the soft magnetic strip material, wherein for generating the soft magnetic strip material from the belt-shaped material it is further provided: determining at least a magnetic measurement of the generated soft magnetic strip material and controlling the tensile force to adjust the tensile stress in response to the detected magnetic measurement.
• the iron-based nanocrystalline alloy for the soft magnetic strip material contains, for example, at least 50 atomic% iron, at most 4 atomic% niobium and at least 15 and at most 20 atomic% silicon. More preferably, the iron-based nanocrystalline alloy contains at most 2 atomic% of niobium. A silicon content of at least 15 at% is advantageous in order to obtain a magnetostriction of less than 1 ppm. A niobium content of at most 4 atomic% is advantageous in order to keep the cost of the magnetic core according to the invention as low as possible. Therefore, a niobium content of at most 2 atomic% is particularly advantageous.
• the iron-based nanocrystalline alloy is an alloy (hereinafter referred to as alloy A) consisting of
• nanocrystalline structure in which at least 50% by volume of the grains have an average size smaller than 100 nm
• An iron-based nanocrystalline alloy containing at least 50 at% of iron, at least 2 and at most 4 at% of niobium and at least 15 and at most 20 at% of silicon is hereinafter referred to as "Alloy B”.
• the band-shaped material may be an alloy having the same constituents as the iron-based nanocrystalline alloy in the same proportions but being an amorphous material.
• the band-shaped material differs in its magnetic Properties of the inventively provided nanocrystalline iron-based alloy. The magnetic properties were adjusted by the process steps, that is, the heat treatment under the action of a tensile force, whereby the soft magnetic strip material is obtained.
• the shape as a band not only makes it possible to produce the iron-based nanocrystalline alloy under tension in a continuous furnace, but also to manufacture a magnetic core having any number of layers.
• the band-shaped material is preferably obtained by a casting method.
• the permeability of the iron-based nanocrystalline alloy which according to the invention should be between 1000 and 3500, can be determined in particular by selecting the tensile stress during the heat treatment.
• the tensile stress can be up to about 800 MPa without the band breaking.
• these currents can be higher, the higher the saturation polarization, J s , of the material.
• the inductance of the magnetic core increases with the permeability and the size.
• the permeability of the iron-based nanocrystalline alloy is between 1000 and 3000.
• the tensile stress applied during the heat treatment is between 10 and 50 MPa.
• the magnetic core has a core mass of less than 4.7 g at a maximum direct current load of 60 A. In another embodiment of the invention, at a maximum DC load of 100 A, the magnetic core has a core mass of less than 5.3 g.
• the iron-based nanocrystalline alloy has a saturation magnetization greater than 1.3 T.
• the saturation magnetization By increasing the saturation magnetization, the magnetic core can be further downsized and its weight reduced. This is possible because, due to the higher saturation, the permeability can be increased without the core saturating early.
• the magnetic cores according to the invention can also be produced more cost-effectively due to the lower Nb content.
• nanocrystalline iron-based alloys with a magnetostriction below 1 ppm have particularly good soft-magnetic properties even with internal stress if the permeability ⁇ is between 1000 and 3500.
• the iron-based nanocrystalline alloy is obtained in the form of a soft magnetic strip material of an amorphous ribbon-shaped material.
• the material is thus provided as a band before undergoing heat treatment under the action of a tensile force to obtain the strip material.
• the strip material may have a thickness of 10 ⁇ to 50 ⁇ . This thickness allows the magnetic core according to the invention to be wound with a large number of layers, which at the same time has a small outer diameter.
• the soft magnetic strip material may be coated with an insulating layer to protect the layers of the magnetic core from isolate each other electrically.
• the layer may be, for example, a polymer layer, a powder coating or a ceramic layer.
• Alloy A has a composition with a niobium content of less than 2 atomic percent (atomic%). This has the advantage that the raw material costs are lower compared to a composition with a higher niobium content, since niobium is a relatively expensive element. Further, the lower limit of the silicon content and the upper limit of the boron content are set so that the alloy in the form of a strip can be produced under a tensile stress in a continuous furnace, thereby achieving the above-mentioned magnetic properties. Thus, despite the lower niobium content, alloy A may also have the desired soft magnetic properties for magnetic core applications with this fabrication process.
• the central part of the hysteresis loop is defined as the part of the hysteresis loop that lies between the anisotropy field strength points that characterize the transition to saturation.
• a linear part of this central part of the hysteresis loop is represented herein by a nonlinearity factor NL of less than 3%, the nonlinearity factor being calculated as follows:
• 5J aU f and 5J a b respectively denote the standard deviation of the magnetization from a compensation straight line by the ascending or descending branch of the hysteresis loop between magnetization values of ⁇ 75% of the saturation polarization J s .
• Alloy A is thus particularly suitable for a magnetic core having a reduced size and a smaller weight with lower raw material costs and at the same time the desired soft magnetic properties for use as a magnetic core.
• the remanence ratio of Alloy A is less than 0.05.
• the hysteresis loop of alloy A is thus even more linear or flat.
• the ratio of coercive force to anisotropic field strength is less than 5%.
• At least 70 volume percent (vol%) of the grains have an average size less than 50 nm. This allows a further increase in the magnetic properties.
• Alloy A is heat-treated in the form of a ribbon under tension to produce the desired magnetic properties.
• Alloy A ie the finished heat-treated strip, is thus also characterized by a structure that has been created by its manufacturing process.
• the crystallites have an average size of about 20 to 25 nm and a remanent stretch in the tape longitudinal direction of between about 0.02% and 0.5%, which is proportional to that applied during the heat treatment. put tension is.
• the crystalline grains may have an elongation of at least 0.02% in a preferred direction.
• Alloy B initially differs from Alloy A in that its niobium content is at least 2 at% and at most 4 at%. For the rest, alloy B corresponds to alloy A.
• a method for producing the magnetic core according to the invention comprises the steps:
• the order of the steps may vary depending on the application.
• a provided strip-shaped material in particular amorphous strip-shaped material, which is subjected to a heat treatment in a subsequent step by application of the heat treatment temperature.
• the band-shaped material is simultaneously applied to the heat treatment and / or subsequently thereto with the described tensile force in order to generate a tensile stress in the band-shaped material.
• an anisotropy for example a transverse anisotropy
• the tensile stress is adjusted such that the soft magnetic strip material produced by the method has a pronounced flat hysteresis loop with a defined permeability ⁇ in the tensile direction.
• the application of the tensile force can take place simultaneously with the heat treatment.
• the induced anisotropy is proportional to the introduced tensile stress, the permeability being dependent on the anisotropy.
• FIGS. 3a and 3b A graphic representation and detailed description of the relationships are given in FIGS. 3a and 3b and the associated description.
• a soft-magnetic strip material with defined magnetic properties or a modified microstructure is produced by means of the described steps and subsequently subjected to a measurement for determining one or more magnetic measured variables.
• the tensile force in the step of controlling the tensile force, is varied such that the tensile stress in the longitudinal direction of the band-shaped material is kept substantially constant at least in sections along the longitudinal direction. Accordingly, the tensile force is changed so that the local tension prevailing in the band-shaped material tension can be kept constant. In this way, it is possible to compensate for an influence on the local tensile stress by the local cross-sectional area fluctuating over the longitudinal course of the band-shaped material due to the production, such that a related oscillation of the associated tensile stress is substantially prevented, as would be the case if only one constant traction would be applied.
• a correspondingly constant anisotropy Ku can be induced, which causes a likewise constant permeability ⁇ .
• further parameters are known which can influence and change an induced anisotropy in such a production method, including, for example, the heat treatment temperature, the passage speed of the strip-shaped material, the path for exposure to the heat treatment temperature (ie, a furnace length), which average) thickness of the band-shaped material, the heat conduction or the heat transfer to the band-shaped material and / or the nature of the selected alloy and parameters of the optional predictable magnetic field.
• the regulation of the tensile stress that is, a variably adjustable in the process Force in the band, used to keep the induced anisotropy K u and thus the permeability ⁇ constant over the band length.
• the force in the belt is varied, for example, in small increments by a nominal tension value in order to compensate for local influences such as temperature differences, belt thickness fluctuations, slight variations in the throughput speed, changes in the composition of the material and so on.
• the induced anisotropy Ku and thus the permeability over a defined section or even over the entire length of the strip-like material can be kept constant. If, by means of the described control, the tension is only kept constant in sections or constantly changed, this additionally opens up the possibility of keeping the tension in a first section at a first value and in a subsequent second section at a second value by changing a corresponding default value , Of course, more than two sections can be provided with an individually set constant tension value. Subsequently, for example, each section can be used for winding a separate magnetic core, and thus magnetic cores with different magnetic properties can be generated in succession.
• controlling the tension includes automatically adjusting the tension by a predefined desired tension value.
• the tensile force introduced into the strip-shaped material can therefore be varied automatically in small steps or continuously by the desired tensile stress value in response to the at least one magnetic measurement variable in order to local influences in the strip-shaped material, such as temperature differences, band diameters. to compensate for fluctuations in the flow rate and / or changes in the material composition.
• the tensile force is steadily controlled, i. there is a constant review and (re) regulation.
• a predefined setpoint can, as described above, also be provided only for a defined section of the strip-shaped material so that individual tensile stress levels can be assigned to one or more successive sections, whereby the induced anisotropy or length over the length of the respective section.
• the targeted permeability can be set in a wide range targeted.
• a permeability ⁇ in the range from below 1000 to 3500 can be achieved depending on a selected material composition of the strip-shaped material or an alloy used for this purpose.
• a relatively low permeability ⁇ is advantageous for current transformers.
• the embodiments described thus offer the advantage that a combination of the two preceding aspects, namely to be able to keep constant the tensile stress over a wide range and to specify a tensile stress level in sections by a respective nominal tensile stress value, is made possible.
• it is not sufficient to introduce only a high tensile force into the band-shaped material in order to achieve the desired permeability, since the target permeability achieved would thus be precisely set only for a specific, local area of the band-shaped material.
• very fine and above all trouble-free traction variations must be able to hold the tension, as described, to be able to maintain a constant value.
• soft magnetic strip material with one or more different respective can be produced by means of the control according to the invention with very small deviations from the predetermined desired permeability value over the entire strip length or over one or more defined sections.
• the method may comprise, as an optional step, the application of a magnetic field (magnetic field treatment) to the band-shaped material, wherein the magnetic field treatment may take place, for example, subsequently or simultaneously to the heat treatment.
• a treatment with more than one magnetic field such as a plurality of magnetic fields, each with a different spatial orientation, are provided.
• the method may further comprise a step of winding at least a defined portion of the generated soft magnetic strip material to produce at least one magnetic core in the form of a toroidal core subsequent to the step of determining the at least one magnetic measurement quantity.
• the strip material produced can thus be wound into one or more annular band cores following the steps described above. Since a permittility profile which is as constant or as continuous as possible is generated at one or more levels by means of the described method, magnetic cores having a respectively very constant permeability distribution within the magnet core but also with small specimen scattering of a plurality of magnetic cores with the same desired permeability value can be produced from this.
• the magnetic cores according to the invention can, with the application of the method according to the invention, be treated with very small specimen scatters of a few than +/- 2.5%. Due to this, the magnetic cores according to the invention can be dimensioned accurately, which results in a significant weight reduction of up to 50% over the prior art.
• the cores produced according to the prior art have a significantly higher specimen scattering of up to +/- 20%. This high tolerance must be maintained in the dimensioning, resulting in larger dimensions and higher core weights.
• the step of winding is controlled in response to the at least one magnetic measurement.
• This allows, for example, a specific winding of defined sections, which are determined via a characterization by means of the determined magnetic measured variable. If, for example, a different permeability level is reached, that is to say a jump in the permeability profile is detected or generated, the winding can be controlled accordingly. For example, the winding of a first magnetic core can be terminated and a winding of a new magnetic core can be started.
• the step of winding comprises winding a defined number of tape layers of the produced soft magnetic strip material to produce the at least one toroidal core, defining the number of tape layers in response to the at least one magnetic measurement.
• the local strip thickness or the magnetic cross-sectional area connected thereto are taken into account for the step of winding.
• a number of band plies may already be determined prior to actual winding and may be varied in the course of the winding such that the wound core has a predefined core cross-sectional area A K Fe. The method described thus offers the possibility of producing a number of cores, each of the cores being next to a defined permeance. along the length of the wound strip material also has a defined core cross-section with a core cross-sectional area.
• the band shape not only allows processing of the alloy under tensile stress in a continuous annealing plant described in more detail below, but also the production of toroidal cores with any number of layers. In this way, the size and the magnetic properties of a toroidal core can be easily adapted to an intended application by an appropriate selection of the number of windings or band layers.
• the number of band layers can be varied such that a cross-sectional area A K Fei of a first annular band core and a cross-sectional area A K Fe2 of a second annular band core are substantially equal. It can thus be generated any number of annular band cores, each with the same size core cross-sectional area, but at least with a very small deviation of the respective core cross-sectional area.
• the number of band layers can, for example, also be varied such that, alternatively or additionally, the permeability of the first ring band core and the permeability of the second ring band core are substantially equal.
• the effect of the at least partially constant permeability and the effect of an equally large core cross-sectional area can be supported by a middle process when winding up the respective core.
• the respective positive and negative deviations from a predefined setpoint compensate each other over a defined length (for example several meters) of the strip material.
• the heat treatment temperature and a passage speed of the belt-shaped material are selected depending on the alloy selected in each case such that a magnetostriction in a nanocrystalline state of the corresponding heat-treated soft magnetic strip material is less than 1 ppm. This is to be regarded as a basic condition in order to wind a magnetic core out of the heat-treated soft magnetic strip material, which has a similar or even the same permeability as the unwound strip material even after the winding process in its wound state.
• the highest possible anisotropy induced in the production process of the soft magnetic strip material causes the core to become increasingly insensitive to the constantly small additional anisotropies due to the winding stresses.
• a corresponding comparison of a hysteresis measured on the unwrapped soft magnetic strip material and a hysteresis determined on the wound ring belt core is shown in FIG. 4.
• the band-shaped material provided as starting material in the context of the described method can be subjected to heat stress under tension in order to produce the desired magnetic properties.
• the chosen temperature is of great importance, since in dependence on this, the structure of the material is affected.
• the heat treatment temperature is above a crystallization temperature of the strip material for transferring the strip material from an amorphous state to a nanocrystalline state.
• the nanocrystalline state is advantageous for the toroidal cores and responsible for excellent soft magnetic properties of the strip material produced.
• the nanocrystalline structure achieves a low saturation magnetostriction with simultaneously high saturation polarization.
• the proposed heat treatment under defined tensile stress results in a suitable magnetic alloy hysteresis with a central linear part. This is associated with low magnetic reversal losses and a permeability which is independent of the applied magnetic field or of the bias in the linear, central part of the hysteresis within wide limits and which are desired in magnetic cores, in particular for current transformers.
• the determination of the at least one magnetic measured variable takes place in real time.
• it is possible to carry out a magnetic characterization "in-line" within a production line during operation An exemplary selection of magnetic measured variables will be described below.
• the band-shaped material or the produced soft-magnetic strip material can pass through a production device at full speed without having to interrupt or slow down the process for the determination.
• the at least one magnetic quantity may be selected from a group consisting of the saturation magnetic flux, the magnetic band cross-sectional area A Fe , the anisotropy field strength, the permeability, the coercive force, and the remanence ratio of the produced soft magnetic strip material. All these measured variables or the associated magnetic properties of the strip material produced have in common that they are dependent on a tensile stress introduced into the material and can thus be regulated accordingly by means of the described method.
• the step of determining the magnetic measured quantity likewise comprises determining the local magnetic cross-sectional area A Fe , this not only allows to produce a soft magnetic strip material which, as described, has as constant a permeability course along its length as possible, but at the same time permits information about to gain the thickness profile of the strip material produced.
• This combination makes it possible to wind from the produced strip material toroidal cores with very precisely adjustable permeability values and simultaneously adjustable core cross-sectional areas A K Fe of the toroidal core, in that a required strip length can already be defined before actual winding.
• a device for producing soft magnetic strip material can be provided with
• an input-side material supply for supplying strip-shaped material, a heat treatment device for heat-treating the strip-like material at a heat treatment temperature, -
• a clamping device for applying the heat-treated strip-shaped material with a tensile force for generating a tensile stress in a band longitudinal axis of the band-shaped material at least in the region of the heat treatment apparatus, wherein
• the tensioning device is designed to vary the tensile force in the band-shaped material controllable to adjust the tensile stress
• the device further comprises a measuring arrangement for determining at least one magnetic measured quantity of the soft magnetic strip material produced and
• a control unit for controlling the tensioning device, which is designed and connected to the measuring arrangement, that the rules of the tensioning device comprises a regulation of the tensile force in response to the at least one determined magnetic measured variable.
• the apparatus may further comprise a winding unit having at least one winding mandrel for winding a defined portion of the produced soft magnetic strip material to produce at least one toroidal core, the winding unit being formed and connected to the measuring arrangement such that the winding is in response to the at least one determined one Measured variable takes place.
• the device may comprise a device for generating at least one magnetic field for applying the heat-treated material to the at least one generated magnetic field.
• the magnetic field may be directed transversely and / or perpendicular to the tape longitudinal axis or band surface.
• the tensioning device for generating the tensile force in the band-shaped material can be configured such that the band-shaped material can nevertheless move continuously and the tensile force can be varied according to the control unit's specification on the basis of the magnetic measured variable determined by the measuring arrangement.
• the clamping device must be able to introduce a sufficiently high tensile force into the band-shaped material and ensure a required accuracy, for example, allow reproducible tensile force changes and apply the predetermined tensile force even with a plastic strain of the band-shaped material and ensure.
• the tensioning device for generating the tensile force comprises two coupled S-shaped roller drives, a dancer control and / or a swing control and torque-controlled brake drives and / or mechanically braked rollers.
• a dancer control and / or a swing control and torque-controlled brake drives and / or mechanically braked rollers are coupled S-shaped roller drives, a dancer control and / or a swing control and torque-controlled brake drives and / or mechanically braked rollers.
• other suitable clamping devices can be used, which meet the requirements mentioned.
• the band-shaped material provided by means of the input-side material supply comprises a material cut and / or cast to a final width and / or cast into a coil.
• the measuring arrangement is arranged in a section following the heat treatment device and / or the tensioning device, so that the soft magnetic strip material that runs through the measuring arrangement is free of the tensile force provided by the tensioning device.
• a certain tension or tensile force can still be present for the transport and winding of the strip material.
• the magnetic core according to the invention can be obtained.
• the soft magnetic strip material may be coated with an insulating layer to electrically insulate the layers of the toroidal core from one another.
• the strip material can be coated with the insulating layer before and / or after winding up to the magnetic core.
• the use of the magnetic core according to the invention is further provided for a current transformer.
• a current transformer By using the magnetic core according to the invention, it is advantageously possible in particular to obtain a DC-tolerant current transformer.
• the requirements to be met by such a current transformer are described in WO 2004/088681 A2 and in standards such as IEC 62053-21 and IEC 62053-23.
• the current transformers with magnetic cores according to the invention meet these requirements.
• the smaller scattering enables targeted optimization of the core dimensions, thus achieving a significant reduction in core weight.
• the core weight may be (iii) increased by
• the saturation magnetization can be further reduced to more than 1.3 T, which is achieved by lowering the Nb content below 2 atomic%.
• FIGS. 3a and 3b fundamentals of tension-induced anisotropy, definition of the mechanical and magnetic terms, and in two diagrams the relationship between a tensile stress introduced into a band-shaped material and a resultant Anisotropy or permeability
• FIG. 4 shows in a diagram the comparison of a hysteresis measured at the unwrapped soft magnetic strip material with a hysteresis determined at the wound core
• FIG. 5 shows a schematic perspective sectional view of an embodiment of a magnetic core.
• FIG. 1 schematically shows an exemplary sequence of the method for producing soft magnetic strip material for magnetic cores in the form of toroidal cores according to a first embodiment.
• the method comprises providing a band-shaped material, heat treating the band-shaped material at a heat treatment temperature. and applying the heat-treated belt-shaped material with a tensile force in a longitudinal direction of the belt-shaped material to generate a tensile stress in the belt-shaped material. These steps serve to generate the soft-magnetic strip material from the strip-shaped material.
• the method comprises determining at least one magnetic measurement of the produced soft magnetic strip material, and controlling the tensile force for adjusting the tensile stress in response to the determined magnetic measurement (arrow A).
• the method comprises a step of winding at least a defined portion of the generated soft magnetic strip material to produce at least one toroidal core subsequent to the step of determining the at least one magnetic measurement quantity.
• the step of winding is controlled in response to the at least one magnetic measurement (arrow B).
• FIG. 2 shows a schematic representation of an apparatus 20 for producing soft magnetic strip material according to an embodiment.
• the apparatus 20 comprises an input-side material feed 21 for providing strip-shaped material, a heat treatment device 22 for heat treatment of the strip-shaped material at a heat treatment temperature, a tensioning device 24 for applying a tensile force to a strip longitudinal axis of the strip-shaped material at least in the area the heat treatment device 22.
• the tensioning device 24 is controllably designed for a variation of the tensile force in the band-shaped material in order to set the desired tensile stress for producing the soft magnetic strip material.
• the device 20 further comprises a measuring arrangement 25 for determining at least one magnetic measured quantity of the produced soft magnetic strip material and a regulating unit 26 for regulating the tensioning device 24, the regulating unit 26 being designed and is connected to the measuring arrangement 25, that the rules of the tensioning device 24 comprises a regulation of the tensile force in response to the at least one determined magnetic parameter.
• the tensioning device 24 comprises two S-shaped roller drives coupled together and a dancer control.
• the roller drives may additionally or alternatively also have different speeds, wherein the first roller drive in the direction of movement of the belt may have a slightly lower drive speed than the following roller drive, whereby an additional tensile force can then be generated between the two roller drives.
• the first role can be braked instead driven.
• the dancer control can also serve to compensate for speed fluctuations in addition to the generation of traction power. Alternatively or additionally, a swing control can be provided.
• the apparatus 20 comprises a device 23 for generating at least one magnetic field for applying the heat-treated strip material to the at least one magnetic field and / or a winding unit 27 having a plurality of winding mandrels 28 for winding a respective defined portion of the produced soft magnetic strip material to produce a number of toroidal cores.
• the winding unit is formed and connected to the measuring arrangement 25, that the winding takes place in response to the at least one determined measured variable.
• the winding unit 27 comprises an additional S-shaped roller drive 29 for feeding the strip material to the respective winding mandrel 28.
• FIGS. 3a and 3b show a relationship between a tensile stress introduced into a band-shaped material 30 by means of a tensile force F and a resulting anisotropy Ku or permeability ⁇ .
• a locally occurring in the band-shaped material 30 tensile ⁇ results from the applied tensile force F and a local magnetic cross-sectional area A Fe (material cross-section) to: F
• the local cross-sectional area A F E fluctuates correspondingly assuming a constant width and with it the tensile stress ⁇ at constant tensile force F.
• This causes a corresponding change in the induced anisotropy Ku, which influences the permeability ⁇ correspondingly via the abovementioned relationships, so that these also change over the length of the soft-magnetic strip material produced hereby from the strip-shaped material.
• 3b also shows a profile of the permeability as a function of the tensile stress ⁇ for three heat treatment temperatures.
• the heat treatment temperature and a flow rate should be adjusted depending on a selected material or a selected alloy such that a magnetostriction in a nanocrystalline state of the strip material is less than 1 ppm.
• the product of bending stresses due to the winding of the strip material and the value of the magnetostriction represents an additional anisotropy induced in the wound strip material and should therefore be kept as small as possible. Otherwise, the permeability of the magnetic core would differ more or less from that of the unwrapped strip material. Thus, the higher the anisotropy induced in creating the unwrapped soft magnetic strip material, the less sensitive the toroidal core becomes to the ever-constant additional anisotropies due to the winding stresses.
• a permeability ⁇ is in a range of 1000. This corresponds to a small to medium-induced induced anisotropy. Except for small defects in an area of magnetic saturation termination, the two hysteresis curves for the unwrapped soft magnetic strip material 60 and wound loop tape core 61 may be considered identical.
• FIG. 5 shows a section through a magnetic core 51 which has a wound annular band core 52 and a coating 53 made of a powder coating.
• the coating 53 fixes the annular band core 52.
• the ring band core 52 has a height h, an outer diameter d a and an inner diameter d ,.
• On the surfaces of the ring band core powder coating 53 is applied.
• the magnetic core 51 has a height H, an outer diameter OD, and an inner diameter ID.
• the tape cross-sectional area A Fe is marked.
• band-shaped materials were selected whose composition is given in Table 1. These band-shaped materials were subjected to a heat treatment and further process steps for producing a soft magnetic strip material, for example, to obtain an iron-based nanocrystalline alloy or a cobalt-based amorphous alloy. Details of the further measures can be found in Table 1, column "Heat Treatment.”
• the strip-like materials of Examples E-1, E-2 and E-3 were subjected to the process according to the invention.
• Table 1 Composition, properties of band-shaped materials and method steps for transferring the band-shaped materials into soft magnetic strip material
• J s denotes the saturation magnetization of the amorphous band-shaped material before crystallization, wherein the saturation magnetization of the nanocrystalline material can then be up to 3% higher.
• the measurement of the saturation magnetization of the amorphous material was chosen because it is much easier to perform than that of the nanocrystalline material with comparable values.
• V-1 and V-2 are comparative examples.
• the term "crystallization" refers to the transfer of the amorphous ribbon-shaped material into a soft-magnetic strip material of an iron-based nanocrystalline alloy.
• the band-shaped materials E-1, E-2 and E-3 are used in the examples according to the invention. Of these, E-2 and E-3 are particularly preferred because their saturation magnetization is greater than 1.3 T.
• the magnetic core can be further downsized from a magnetic core using Example E-1 and Comparative Examples V-1 and V-2, and its weight can be reduced. This is possible because, due to the higher saturation, the permeability can be increased without the magnetic core saturating early.
• a magnetic core of E-2 and E-3 compared to Example E-1 and Comparative Examples V-1 and V-2 can also be produced more cost-effectively due to the lower Nb content.
• Table 2 shows Examples E-1 a, E-2a and E-3a and Comparative Examples V-1a and V-2a for magnetic cores obtained from the strip material produced according to Table 1 and intended for 60 A current transformers. E-2a and E-3a are preferred examples.
• Table 3 shows Examples E-1 b, E-2b and E-3b and Comparative Examples V-1 b and V-2b for magnetic cores obtained from the strip material produced according to Table 1 and intended for 100 A current transformers. E-2b and E-3b are preferred examples.
• the magnetic cores Due to the low magnetostriction (A s ⁇ 1 ppm) of the magnetic cores according to the invention they are insensitive to mechanical stresses. It was therefore possible to fix the toroidal cores by a thin coating with a powder coating. Such a type of fixation enables a size reduction of the magnetic core, but due to the mechanical stresses introduced in this case, it is only possible with magnetic cores which have a small magnetostriction. For magnetostriction values greater than 1 ppm, the mentioned mechanical stresses would significantly degrade the linearity of the phase error of the core transformer. For example, the alloy VC 220 F has a high magnetostriction of 10 ppm. Therefore, when using this alloy, the magnetic core had to be carefully grafted with as little stress as possible, which leads to the comparatively large dimensions of the corresponding core types (see V-2a in Table 2 and V-2b in Table 3).
• the column “core dimension” represents the dimensions of the ring band core without coating 53 (see Fig. 5) .
• the column “core fixed” shows the dimensions of the ring band core provided with a powder coating 53.
• the magnetic cores according to the invention were produced using the method according to the invention with very low specimen scattering of less than +/- 2.5%. Because of this, the magnetic cores according to the invention could be accurately dimensioned, which compared to the prior art results in a significant weight reduction of up to 50%.
• the cores produced according to the prior art have a significantly higher specimen scattering of up to +/- 20%. This high tolerance must be maintained in the dimensioning, resulting in larger dimensions and higher core weights.
• a nominal value is a suitable, rounded value of a variable for designating or identifying a device or a system) of the magnetic cores.

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=49486453

Family Applications (1)

Country Status (4)

Cited By (2)

Families Citing this family (10)

Citations (5)

Family Cites Families (5)

• 2012
  • 2012-10-12 DE DE102012218656.5A patent/DE102012218656A1/de active Pending
• 2013
  • 2013-10-09 US US14/434,894 patent/US20150255203A1/en not_active Abandoned
  • 2013-10-09 CN CN201380053051.4A patent/CN104823250B/zh active Active
  • 2013-10-09 WO PCT/EP2013/071027 patent/WO2014056972A1/de active Application Filing

Patent Citations (5)

Also Published As

Similar Documents

Legal Events