Source: http://www.google.com/patents/US7026905?dq=6272333
Timestamp: 2016-08-25 02:42:55
Document Index: 221719716

Matched Legal Cases: ['Application No. 60', 'Application No. 2000', 'arts 10', 'art 16', 'arts 16', 'arts 16']

Patent US7026905 - Magnetically controlled inductive device - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsA controllable inductor, comprising first and second coaxial and concentric pipe elements, where said elements are connected to one another at both ends by means of magnetic end couplers, a first winding wound around both said elements, and a second winding wound around at least one of said elements,...http://www.google.com/patents/US7026905?utm_source=gb-gplus-sharePatent US7026905 - Magnetically controlled inductive deviceAdvanced Patent SearchPublication numberUS7026905 B2Publication typeGrantApplication numberUS 10/685,345Publication dateApr 11, 2006Filing dateOct 14, 2003Priority dateMay 24, 2000Fee statusPaidAlso published asUS7256678, US20040135661, US20060152324Publication number10685345, 685345, US 7026905 B2, US 7026905B2, US-B2-7026905, US7026905 B2, US7026905B2InventorsEspen Haugs, Frank StrandOriginal AssigneeMagtech AsExport CitationBiBTeX, EndNote, RefManPatent Citations (49), Non-Patent Citations (16), Referenced by (8), Classifications (18), Legal Events (5) External Links: USPTO, USPTO Assignment, EspacenetMagnetically controlled inductive device
US 7026905 B2Abstract
A controllable inductor, comprising first and second coaxial and concentric pipe elements, where said elements are connected to one another at both ends by means of magnetic end couplers, a first winding wound around both said elements, and a second winding wound around at least one of said elements, where the winding axis for the first element is perpendicular to the elements' axes and the winding axis of the second winding coincides with the elements' axes, characterized in that said first and second magnetic elements are made from anisotropic magnetic material such that the magnetic permeability in the direction of a magnetic field introduced by the first of said windings is significantly higher than the magnetic permeability in the direction of a magnetic field introduced by the second of said windings.
1. A controllable inductor, comprising:
first and second coaxial and concentric magnetic pipe elements comprising anisotropic material, wherein said elements are connected to one another at both ends by means of magnetic end couplers;
a first winding wound around both said magnetic pipe elements; and
a second winding wound around at least one of said magnetic pipe elements,
wherein a winding axis for the first winding is perpendicular to an axis of at least one of the magnetic pipe elements,
wherein a winding axis of the second winding coincides with the axis,
wherein, when energized, the first winding generates a magnetic field in a first direction that coincides to a direction of a first magnetic permeability,
wherein, when energized, the second winding generates a magnetic field in a second direction that coincides to a direction of a second magnetic permeability, and
wherein the first magnetic permeability is substantially higher than the second magnetic permeability.
2. The controllable inductor according to claim 1, wherein the anisotropic material is selected from a group consisting of grain oriented silicon steel and domain controlled high permeability grain oriented silicon steel.
3. The controllable inductor according to claim 1, wherein the magnetic end couplers are made of an anisotropic material and provide a low permeability path for the magnetic field created by the first winding and a high permeability path for the magnetic field created by the second winding.
4. The controllable inductor according to claim 1, further comprising a thin insulation sheet situated between magnetic pipe element edges and the end couplers.
5. The controllable inductor according to claim 1, wherein a volume of the magnetic end couplers is 10–20% of the volume of the magnetic pipe elements.
6. The controllable inductor according to claim 1, wherein a volume of the magnetic end couplers is 25–50% of the volume of the magnetic pipe elements.
7. The controllable inductor of claim 1 wherein the magnetic field direction introduced by the first winding is in an annular direction relative to the axis of at least one of the elements.
8. The controllable inductor of claim 1 wherein the magnetic field direction introduced by the second winding is in a radial direction relative to the axis of at least one of the elements.
This application is a continuation-in-part of currently application Ser. No. 10/278,908, filed on Oct. 24, 2002, now U.S. Pat. No. 6,933,822, which claims priority to U.S. Provisional Application No. 60/330,562, filed Oct. 25, 2001, and which is a continuation of PCT International Application No. PCT/NO01/00217, filed May 23, 2001, which claims priority to Norwegian Patent Application No. 2000 2652, filed May 24, 2000, the contents of each of these applications are incorporated herein by reference.
The present invention relates to a controllable inductive device, and more particularly a controllable inductive device comprising an anisotropic material.
There is a long standing interest in using a control field to control a main field in an inductive device. For example, U.S. Pat. No. 4,210,859 describes a device comprising an inner cylinder and an outer cylinder joined to one another at the ends by means of connection elements. In this device the main winding is wound around the core and passes through the cylinder's central aperture. The winding axis follows a path along the cylinder's periphery. This winding creates an annular magnetic field in the cylinder's wall and circular fields in the connection elements. The control winding is wound around the cylinder's axis. It will thus create a field in the cylinder's longitudinal direction. The core's permeability is changed by the action of a control current applied to the control winding. Because the cylinders and the connection elements are made of the same material, the rate of change of permeability is the same in both types of elements. Consequently, the magnitude of the control field must be limited to prevent saturation of the core and decomposition of the control field. As a result, the control range of this inductor is limited, and the device, in U.S. Pat. No. 4,210,859, has a relatively small volume that limits the device's power handing capability.
Other devices include controlled permeability of only part of the main flux path. However, such an approach dramatically limits the control range of the device. For example, U.S. Pat. No. 4,393,157 describes a variable inductor made of anisotropic sheet strip material. This inductor comprises two ring elements joined perpendicularly to one another with a limited intersection area. Each ring element has a winding. The part of the device where magnetic field control can be performed is limited to the area where the rings intersect. The limited controllable area is a relatively small portion of the closed magnetic circuits for the main field and the control field. Part of the core will saturate first (saturation will not be attained simultaneously for all parts of the core because different fields act upon different areas) and this saturation will result in losses generated by stray fields from the main flux. Partial saturation results in a device with a very limited control span.
Thus, the prior art lacks a means to control permeability in a core for substantial power handling capability without introducing considerable losses. The shortcomings of the prior art effect all inductive device geometries, and in particular, curved structures made of sheet strip metal because considerable eddy currents and hysteresis losses occur in these types of curved structures.
The invention addresses these shortcomings and can be implemented in a low loss controllable inductive device suitable for high power applications. Generally, the invention can be used to control the magnetic flux conduction in a rolling direction by controlled domain displacement in a transverse direction.
In one aspect, the invention controls the permeability of grain-oriented material in the rolling direction by employing a control field in the transverse direction. In one embodiment, a controllable inductive device of grain-oriented steel is magnetized in the transverse direction. In another embodiment, a controllable inductor comprising first and second coaxial and concentric pipe elements is provided. The elements are connected to one another at both ends by means of magnetic end couplers. A first winding is wound around both said elements, and a second winding is wound around at least one of said elements. The winding axis for the first winding is perpendicular to the elements' axes and the winding axis of the second winding coincides with the elements' axes. The first and second magnetic elements are made from an anisotropic magnetic material such that the magnetic permeability in the direction of a magnetic field introduced by the first of the windings is significantly higher than the magnetic permeability in the direction of a magnetic field introduced by the second of the windings. In a version of this embodiment, the anisotropic material is selected from a group consisting of grain-oriented silicon steel and domain controlled high permeability grain oriented silicon steel.
In one embodiment, the magnetic end couplers are made of anisotropic material and provide a low permeability path for the magnetic field created by the first winding and a high permeability path for the magnetic field created by the second winding. The controllable inductor may also include a thin insulation sheet situated between magnetic pipe element edges and the end couplers.
In a further embodiment, the invention provides a controllable magnetic structure that includes a closed magnetic circuit. The closed magnetic circuit includes a magnetic circuit first element, and a magnetic circuit second element. Each of the magnetic circuit elements is manufactured from an anisotropic material having a high permeability direction. The controllable magnetic structure also includes a first winding which is wound around a first portion of the closed magnetic circuit, and a second winding which is oriented orthogonal to the first winding. The first winding generates a first magnetic field in the high permeability direction of the first circuit element and the second winding generates a second field in a direction orthogonal to the first field direction when the respective windings are excited (i.e., energized).
In a version of this embodiment, the controllable magnetic structure includes a first circuit element that is a pipe member and a magnetic circuit second element that is an end coupler that connects a first pipe member to a second pipe member. In a version of this embodiment, the first pipe member and the second pipe member are located coaxially around an axis and the high permeability direction is an annular direction relative to the axis. Additionally, the second high permeability direction can be in a radial direction relative to the axis. In another version of this embodiment, the controllable magnetic structure is manufactured from grain-oriented material. In yet another version of this embodiment, the controllable magnetic structure is an inductor.
In another embodiment, insulation is located in the closed magnetic circuit between the magnetic circuit first element and the magnetic second element. In another embodiment, the magnetic circuit second element has a volume that is 10% to 20% of the volume of the magnetic circuit first element.
In still another embodiment of the invention, a core is provided for a magnetic controllable inductor. The core includes first and second coaxial and concentric pipe elements and each pipe element is manufactured from an anisotropic magnetic material. An axis is defined by each pipe element and the pipe elements are connected to one another at both ends by means of magnetic end couplers. In addition, the core presents a first magnetic permeability in a first direction parallel to the axes of the elements that is significantly higher than a second magnetic permeability in a second direction orthogonal to the elements' axes. In a version of this embodiment, first and second pipe elements are made of a rolled sheet material comprising a sheet end and a coating of an insulation material. In another version, the first pipe element includes a gap in the third direction parallel to the axes of the elements and the first and second pipe elements are joined together by means of a micrometer thin insulating layer in a joint located between the first and second pipe elements. In a further version, an air gap extends in an axial direction in each pipe element and a first reluctance of a first element equals a second reluctance of the second element. In one embodiment, the insulation material is selected from a group consisting of MAGNETITE-S and UNISIL-H. Further, the controllable inductor can include a third magnetic permeability that exists in the couplers in an annular direction relative to the axes of the elements and a fourth magnetic permeability that exists in the coupler in a radial direction relative to the axes of the elements. In a version of this embodiment, the fourth magnetic permeability is substantially greater than the third magnetic permeability.
In another aspect of the invention, a magnetic coupler device is provided to connect first and second coaxial and concentric pipe elements to one another to provide a magnetic core for a controllable inductor. The magnetic end couplers are manufactured from anisotropic material and provide a low permeability path for magnetic field created by the first winding and a high permeability path for magnetic field created by a second winding. In a version of this embodiment, the magnetic coupler includes grain-oriented sheet metal with a transverse direction that corresponds to the grain-oriented direction of pipe elements in an assembled core. In addition, the grain-oriented direction corresponds to the transverse direction of the pipe elements in the assembled core to assure that the end couplers get saturated after the pipe elements. In a version of this embodiment, the magnetic end couplers are manufactured from a single wire of magnetic material. In another version of this embodiment, the magnetic end couplers are manufactured from stranded wires of magnetic material.
The magnetic end couplers may be produced by a variety of means. In one embodiment, the end couplers are produced by rolling a magnetic sheet material to form a toroidal core. The core is sized and shaped to fit the pipe elements, and the cores are divided into two halves along a plain perpendicular to the material's Grain Orientation (GO) direction. Additionally, the end coupler width is adjusted to make the segments connect the first pipe element to the second pipe element at the pipe element ends. In another embodiment, the magnetic end couplers are produced from either stranded or single wire magnetic material wound to form a torus and the torus is divided into two halves along a plane perpendicular to all the wires.
In another embodiment, the invention implements a variable inductive device with low remanence, so that the device can easily be reset between working cycles in AC operation and can provide an approximately linear, large inductance variation.
The invention will now be described in detail by means of examples illustrated in the following drawings.
FIG. 3 is a schematic illustration of an embodiment of the device according to an embodiment of the invention.
FIG. 4 illustrates the areas of the different magnetic fluxes which form part of the device according to an embodiment of the invention.
FIG. 5 illustrates a first equivalent circuit for the device according to an embodiment of the invention.
FIG. 6 is a simplified block diagram of the device according to an embodiment of the invention.
FIGS. 8 and 9 illustrate magnetisation curves and domains for the magnetic material in the device according to an embodiment of the invention.
FIGS. 15–18 illustrate different embodiments of the magnetic field connectors in the said second embodiment of the invention.
FIGS. 19–32 illustrate different embodiments of the tubular bodies in the second embodiment of the invention.
FIGS. 33–38 illustrate different aspects of the magnetic field connectors for use in the second embodiment of the invention.
FIGS. 50 and 51 are sections along lines VI—VI and V—V in FIG. 48.
FIG. 54 is an “X-ray picture” of a variant of the fourth embodiment of the invention.
In FIGS. 59 and 60 there are proposals for electro-technical schematic symbols for the voltage converter according to an embodiment of the invention.
FIG. 61 illustrates the use of an embodiment of the invention in an alternating current circuit.
FIG. 62 illustrates the use of an embodiment of the invention in a three-phase system.
FIG. 65 illustrates a simplified reluctance model for the device according to an embodiment of the invention and a simplified electrical equivalent diagram for the connector according to an embodiment of the invention.
FIG. 67 illustrates examples of a three-phase use of an embodiment of the invention.
FIG. 69 illustrates a circuit comprising 6 devices according to an embodiment of the invention.
FIG. 70 illustrates the use of the device according to an embodiment of the invention as a DC-AC converter.
FIG. 71 illustrates a use of the device according to an embodiment of the invention as an AC-DC converter.
FIG. 72 shows a sheet of magnetic material and the relative position of the rolling and axial direction.
FIG. 73 shows a rolled core and the rolling and axial directions defined in it.
FIG. 74 shows a sheet of grain oriented material and the grain and transverse directions defined in it.
FIG. 75 shows a rolled core of grain oriented material, and the grain and transverse directions defined in it.
FIG. 76 shows the relative positions of the different directions in a pipe element.
FIG. 77 shows schematically a part of a device according to an embodiment of the invention.
FIG. 78 shows the device according to the embodiment of FIG. 77.
FIG. 79 shows sectional view of the device shown in FIG. 78.
FIG. 80 shows the position of thin insulation sheets between the magnetic end couplers and the cylindrical cores of a device according to an embodiment of the invention.
FIG. 81 shows production of magnetic end couplers based on magnetic sheet material.
FIG. 82 shows a torus for production of magnetic end couplers based on strands of magnetic material.
FIG. 83 shows a cross section of torus shaped magnetic material for production of magnetic end couplers according to an embodiment of the invention.
FIG. 84 shows the grain and transverse direction in magnetic end couplers according to an embodiment of the invention.
FIG. 85 shows a view of a torus for production of magnetic end couplers whose shape is adjusted to fit pipe elements in accordance with an embodiment of the invention.
FIG. 86 shows a torus produce with magnetic wire according to an embodiment of the invention.
FIG. 87 shows a crossectional view of the torus of FIG. 86.
FIG. 88 shows the domain structure in grain oriented material.
The invention will now be explained in principle in connection with FIGS. 1 a and 1 b. In the entire description, the arrows associated with magnetic field and flux will substantially indicate the directions thereof within the magnetic material. The arrows are drawn on the outside for the sake of clarity.
FIG. 1 a illustrates a device comprising a body 1 of a magnetisable material which forms a closed magnetic circuit. This magnetisable body or core 1 may be annular or of another suitable shape. Round the body 1 is wound a first main winding 2, and the direction of the magnetic field H1 (corresponding to the direction of the flux density B1) which will be created when the main winding 2 is excited will follow the magnetic circuit. The main winding 2 corresponds to a winding in an ordinary transformer. In an embodiment the device includes a second main winding 3 which in the same way as the main winding 2 is wound round the magnetisable body 1 and which will thereby provide a magnetic field which extends substantially along the body 1 (i.e. parallel to H1, B1). The device finally includes a third main winding 4 which in a preferred embodiment of the invention extends internally along the magnetic body 1. The magnetic field H2 (and thus the magnetic flux density B2) which is created when the third main winding 4 is excited will have a direction which is at right angles to the direction of the fields in the first and the second main winding (direction of H1, B1). The invention may also include a fourth main winding 5 which is wound round a leg of the body 1. When the fourth main winding 5 is excited, it will produce a magnetic field with a direction which is at right angles both to the field in the first (H1), the second and the third main winding (H2) (FIG. 3). This will naturally require the use of a closed magnetic circuit for the field which is created by the fourth main winding. This circuit is not illustrated in the Figure, since the Figure is only intended to illustrate the relative positions of the windings.
FIGS. 1 b–1 g illustrate the definition of the axes and the direction of the different windings and the magnetic body. With regard to the windings, we shall call the axis the perpendicular to the surface which is restricted by each turn. The main winding 2 will have an axis A2, the main winding 3 an axis A3 and the control winding 4 an axis A4.
The magnetisation current in an electrical conductor which is enclosed by a ferromagnetic material is limited by the reluctance according to Faraday's Law. The flux which has to be established in order to generate counter-induced voltage depends on the reluctance in the magnetic material enclosing the conductor.
The extent of the magnetisation current is determined by the amount of flux which has to be established in order to balance applied voltage.
In general the following steady-state equation applies for sinusoidal voltage:
Where there is low reluctance (iron enclosure), according to expression 2) above, little current will be required in order to establish the necessary flux, and supplied voltage will overlay the connector. In the case of high reluctance (air) on the other hand, a large current will be required in order to establish the necessary flux. In this case the current will then be limited by the voltage over the load and the voltage induced in the connector. The difference between reluctance in air and reluctance in magnetic material may be of the order of 1.000–900.000.
For the systems which have to be evaluated the following applies:
∫{overscore (H)}.{overscore (ds)}=I.N
{overscore (H)}=field intensity s=the integration path I=current in winding N=number of windings
Flux density or induction:
{overscore (β)}=μ0 �μr{overscore (H)}
{overscore (H)}=magnetic field intensity The ratio between magnetic induction and field intensity is non-linear, with the result that when the field intensity increases above a certain limit, the flux density will not increase and on account of a saturation phenomenon which is due to the fact that the magnetic domains in a ferromagnetic material are in a state of saturation. Thus it is desirable to provide a control field H2 which is perpendicular to a working field H1 in the magnetic material in order to control the saturation in the magnetisable material, while avoiding magnetic connection between the two fields and thereby avoiding transformative or inductive connection. Transformative connection means a connection where two windings “share” a field, with the result that a change in the field from one winding will lead to a change in the field in the other winding.
Since the windings 2 and 4 are placed at 90� to each other, B1 and B2 will be orthogonally located. In the magnetisable body 1, B1 will be oriented transversally and B2 longitudinally. In this connection we refer particularly to what is illustrated in FIGS. 1–4.
{overscore (B)}={overscore (B)} 1 +{overscore (B)} 2 5)
The vector sum of the fields H1 and H2 will determine the total field in the body 1, and thus the body's 1 condition with regard to saturation, and will also determine the magnetisation current and the voltage which is divided between a load connected to the main winding 2 and the connector. Since the sources for B1 and B2 will be located orthogonally to each other, none of the fields will be able to be decomposed into the other. This means that B1 cannot be a function of B2 and vice versa. However, B, which is the vector sum of B1 and B2 will be influenced by the extent of each of them.
B2 is the vector which is generated by the control current. The cross-sectional surface A2 for the B2 vector will be the transversal surface of the magnetic body 1, cf. FIG. 4 c. This may be a small surface limited by the thickness of the magnetisable body 1, given by the surface sector between the internal and external diameters of the body 1, in the case of an annular body. The cross-sectional surface A1 (see FIGS. 4 a, b) for the B1 field on the other hand is given by the length of the magnetic core and the rating of applied voltage. This surface will be able to be 5–10 times larger than the surface of the control flux density B2, without this being considered limiting for the invention.
A2=Area of control flux density B2 l2=Length of flux path for control flux
curl ( H _ ) = J _ + ⅆ ⅆ t D _ 7 ) is simplified to
curl({overscore (H)})={overscore (J)} 8)
∫({overscore (H)}){overscore (dl)}=I 9)
H 1 l 1 =N 1 �I 1 11)
F 1 =N 1 �I 1 12)
H 2 �I 2 =N 2 I 2 13)
F 2 =N 2 I 2 14)
{overscore (B)} 1=μ0 �μr 1 �{overscore (H)} 1 15)
{overscore (B)} 2=μ0 �μr 2 �{overscore (H)} 2 16)
Φ1=∫Aj 0 {overscore (B)} 1 �{overscore (n)}ds 19)
The invention is based on the physical fact that the differential of the magnetic field intensity which has its source in the current in a conductor is expressed by curl to the H field. Curl to H says something about the differential or the field change of the H field across the field direction of H. In our case we have calculated the field on the basis that the surface perpendicular of the differential field loop has the same direction as the current. This means that the fields from the current-carrying conductors forming the windings which are perpendicular to each other are also orthogonal. The fact that the fields are perpendicular to each other is important in relation to the orientation of the domains in the material.
In the device according to the invention a “virtual” air gap is generated through saturation phenomena in the domains. In this case the energy storage will take place in a distributed air gap comprising the whole core. We consider the actual magnetic energy storage system to be free for losses, and any losses will thus be represented by external components.
dWelin=differential electrical energy supply
dWfld=differential change in magnetically stored energy
From equation 26) we have
In the device according to the invention L will be varied as a function of pr, the relative permeability in the magnetisable body or the core 1, which in turn is a function of I2, the control current in the control winding 4.
When L is varied by means of I2, the field energy will be altered as a result of the altered value of L, and thereby the current I will also be altered it is associated with the field value through the flux turns λ.
From the preceding, we can draw the conclusion that the field energy and the energy distribution will be controllable via μr and influence how energy stored in the field is increased and decreased. When the field energy is decreased, the surplus portion will be returned to the generator. Or if we have an extra winding (e.g. winding 3, FIG. 1) in the same winding window as the first main winding 2 and with the same winding axis as the winding axis of main winding 2, this provides a transformative transfer of energy from the first winding 2 to the second main winding 3.
This is illustrated in FIG. 7 where an alteration of λ results in an alteration of the energy in the field Wflt which originally is Wflt(λo, io). A variation is envisaged here which is so small that i is approximately constant during the alteration of λ. In the same way an alteration of i will give an alteration of λ.
When we look at our variable inductance, therefore, we can say the following:
We now refer back to FIGS. 8 and 9. By means of a partial magnetisation of the domains by the control field B2 (H2), an additional field B1 (H1) from the main winding 2 will be added vectorially to the control field B2 (H2). The domains are further magnetized and, as a result, the inductance of the main winding 2 will start from the basis given by the state of the domains under the influence of the control field B2 (H2).
FIG. 13 illustrates a section along line II in FIG. 12 b. As illustrated in the Figures the magnetisable body 1 is composed of inter alia two parallel tubes 6 and 7 made of magnetisable material. An electrically insulated conductor 8 (FIGS. 12 a, 13) is passed continuously in a path through the first tube 6 and the second tube 7 N number of times, where N=1, . . . r, forming the first main winding 2, with the conductor 8 extending in the opposite direction through the two tubes 6 and 7, as is clearly illustrated in FIG. 13. Even though the conductor 8 is only shown extending through the first tube 6 and the second tube 7 twice, it should be self-explanatory that it is possible for the conductor 8 to extend through respective tubes either only once or possibly several times (as indicated by the fact that the winding number N can vary from 0 to r), in order to create a magnetic field H1 in the parallel tubes 6 and 7 when the conductor is excited. A combined control and magnetisation winding 4, 4′, composed of the conductor 9, is wound round the first tube and the second tube (6 and 7 respectively) in such a manner that the direction of the field H2 (B2) which is created in the said tubes when the winding 4 is excited will be oppositely directed, as indicated by the arrows for the field B2 (H2) in FIG. 11. The magnetic field connectors 10, 11 are mounted at the ends of the respective pipes 6, 7 in order to interconnect the tubes fieldwise in a loop. The conductor 8 will be able to carry a load current I1 (FIG. 12 a). The tubes' 6, 7 length and diameter will be determined on the basis of the power and voltage which have to be connected. The number of turns N1 on the main winding 2 will be determined by the reverse blocking ability for voltage and the cross-sectional area of the extent of the working flux φ2. The number of turns N2 on the control winding 4 is determined by the fields required for saturation of the magnetisable body 1, which comprises the tubes 6, 7 and the magnetic field connectors 10, 11.
FIG. 14 illustrates a special design of the main winding 2 in the device according to the invention. In reality, the solution in FIG. 14 differs from that illustrated in FIGS. 12 and 13 only by the fact that instead of a single insulated conductor 8 which is passed through the pipes 6 and 7, two separate oppositely directed conductors, so-called primary conductors 8 and secondary conductors 8′ are employed, in order thereby to achieve a voltage converter function for the magnetically influenced device according to the invention. This will now be explained in more detail. The design is basically similar to that illustrated in FIGS. 11, 12 and 13. The magnetisable body 1 comprises two parallel tubes 6 and 7. An electrically insulated primary conductor 8 is passed continuously in a path through the first tube 6 and the second tube 7 N1 number of times, where N1=1, . . . r, with the primary conductor 8 extending in the opposite direction through the two tubes 6 and 7. An electrically insulated secondary conductor 8′ is passed continuously in a path through the first tube 6 and the second tube 7 N1′ number of times, where N1′=1, . . . r, with the secondary conductor 8′ extending in the opposite direction relative to the primary conductor 8 through the two tubes 6 and 7. At least one combined control and magnetisation winding 4 and 4′ is wound round the first tube 6 and the second tube 7 respectively, with the result that the field direction created on the said tube is oppositely directed. As for the embodiment according to FIGS. 11, 12 and 13, magnetic field connectors 10, 11 are mounted on the end of respective tubes (6, 7) in order to interconnect the tubes 6 and 7 fieldwise in a loop, thereby forming the magnetisable body 1. Even though for the sake of simplicity the primary conductor 8 and the secondary conductor 8′ are illustrated in the drawings with only one pass through the tubes 6 and 7, it will be immediately apparent that both the primary conductor 8 and the secondary conductor 8′ will be able to be passed through the tubes 6 and 7 N1 and N1′ number of times respectively. The tubes' 6 and 7 length and diameter will be determined on the basis of the power and voltage which have to be converted. For a transformer with a conversion ratio (N1:N1′) equal to 10:1, in practice ten conductors will be used as primary conductors 8 and only one secondary conductor 8′.
FIGS. 19–32 illustrate various embodiments of a core 16 which in the embodiment illustrated in FIGS. 12, 13 and 14 forms the main part of the tubes 6 and 7 which preferably together with the magnetic field connectors 10 and 11 form the magnetisable body 1.
FIGS. 33 and 34 illustrate a magnetic field connector 10, 11 which can be used as a control field connector between the rectangular and square main cores 16 (illustrated in FIGS. 20–21 and 23–25 respectively). This magnetic field connector comprises three parts 10′, 10″ and 19.
FIGS. 36–38 illustrate various designs of the magnetic field connector 10, 11, which are based on the fact that the connecting surfaces 14′ of the magnetic field connector 10, 11 are at the same angle as the end surfaces 14 to the core part 16.
In FIG. 39 an embodiment of the invention is illustrated with an assembly of magnetic field connectors 10, 11 and core parts 16. FIG. 39 b illustrates the same embodiment viewed from the side.
FIGS. 42–44 illustrate various embodiments of the magnetic field connector 10, 11 which are specially adapted to the latter design of the invention, i.e. as described in connection with FIGS. 40 and 41.
FIGS. 43 and 44 illustrate other variants of the magnetic field connector 10, 11, where the connecting surfaces 14′ of the control field H2 (B2) are perpendicular to the main axis of the core parts 16 (tubes 20, 21).
FIG. 43 illustrates a hollow semi-toroidal magnetic field connector 10, 11 with a hollow semi-circular cross section, while FIG. 44 illustrates a toroidal magnetic field connector with a rectangular cross section.
A variant of the device illustrated in FIGS. 40 and 41 is illustrated in FIG. 45, where FIG. 45 a illustrates the device from the side while 45 b illustrates it from above. The only difference from the voltage connector in FIGS. 40–41 is that a second main winding 3 is wound in the same course as the main winding 2. By this means an easily constructed, but efficient magnetically influenced voltage converter is obtained.
By supplying control current I2 in the positive half-period of the alternating voltage V1 in 2, we shall obtain a half-period voltage over 2. Since the energy is transferred by flux displacement between the reluctance-controlled core 24 and the external (secondary) core 25, the reluctance-controlled core 24 will essentially be influenced by the control current I2 during the period when it is controlled in saturation, while the working flux will travel in the secondary external core 25 and interact with the primary winding 2 during the energy transfer.
FIG. 50 illustrates the device in FIG. 48 in section along line VI—VI in FIG. 48 and FIG. 51 illustrates a section along line V—V. In FIG. 50 a circular aperture 12 is illustrated for placing the control winding 4.
Φ=Φk+Φ1 40)
Φp=total flux established by the current in 2.
Φk=the total flux travelling through the control core 24.
Φ1=part of the total flux travelling through the main core 25.
Since the leakage flux in main core 24 and control core 25 are disregarded,
When the switch is on, i.e. when the reluctance in the control core 24 is very low (μr=10–50) and approaching the reluctance of an air coil, we will have a very good flux connection between primary 2 and secondary 3 winding and transfer of energy.
In the application as an adjustable transformer, it must be emphasised that the size of the reluctance-controlled core is determined by the range of adjustment which is required for the transformer, (0–100% or 80–110%) for the voltage.
FIG. 69 illustrates a circuit comprising 6 devices 28–33 according to the invention. The devices 28–33 are employed as frequency converters where the period of the voltages generated is composed of parts of the fundamental frequency. This works by “letting through” only the positive half-periods or parts of the half-periods of a sinus voltage in order to make the positive new half-period in the new sinus voltage, and subsequently the negative half-periods or parts of the negative half-periods in order thereby to make the negative half-periods in the new sinus voltage. In this way a sinus voltage is generated with a frequency from 10% to 100% of the fundamental frequency. This converter also acts as a soft start since the voltage on the output is regulated via the reluctance control of the connection between the primary and the secondary winding.
FIG. 70 illustrates the use of the device according to the invention as a DC to AC converter. Here the main winding 2 in the connector is excited by a DC voltage U1 which establishes a field H1 (B1) both in the control core 24 and in the main core 25 (these are not shown in the Figure). The number of turns N1, N2, N3 and the area of iron are designed in such a manner that none of the cores are in saturation in steady state. In the event of a control signal (i.e. excitation of the control winding 4) into the control core 24, the flux B2 (H2) therein will be transferred to the main core 25 and a change in the flux B1 (H1) in this core 25 will induce a voltage in the secondary winding (main winding 3). By having a sinusoidal control current I2, a sinusoidal voltage will be able to be generated on the secondary side (main winding 3), with the same frequency as the control voltage FIG. 70 b illustrates the use of the invention as a converter with a change of reluctance.
As mentioned previously, the voltage connector according to the invention is substantially without movable parts for the absorption of electrical voltage between a generator and a load. The function of the connector is to be able to control the voltage between the generator and the load from 0–100% by means of a small control current. A second function will be purely as a voltage switch. A further function could be forming and transforming of a voltage curve.
The new technology according to the invention will be capable of being used for upgrading existing diode rectifiers, where there is a need for regulation. In connection with 12-pulse or 24-pulse rectifier systems, it will be possible to balance voltages in the system in a simple manner while having controllable rectification from 0–100%.
a) Iron—silicon steel: produced as a strip of a thickness approximately 0.1 mm–0.3 mm and width from 10 mm to 1100 mm and rolled up into coils. Perhaps the most preferred for large cores on account of price and already developed production technology. For use at low frequencies. b) Iron—nickel alloys (permalloys) and/or iron—cobalt alloys (permendur) produced as a strip rolled up into coils. These are alloys with special magnetic properties with subgroups where very special properties have been cultivated. c) Amorphous alloys, METGLAS: produced as a strip of a thickness of approximately 20 μm–50 μm, width from 4 mm to 200 mm and rolled up into coils. Very high permeability, very low loss, can be made with almost 0 magnetostriction. Exists in a countless number of variants, iron-based, cobalt-based, etc. Fantastic properties but high price. d) Soft ferrites: Sintered in special forms developed for the converter industry. Used at high frequencies due to small loss. Low flux density. Low loss. Restrictions on physically realisable size. e) Compressed powder cores: Compressed iron powder alloy in special shapes developed for special applications. Low permeability, maximum approximately 400–600 to-day. Low loss, but high flux density. Can be produced in very complicated shapes. All sintered and press-moulded cores can implement the topologies which are relevant in connection with the invention without the need for special magnetic field connectors, since the actual shape is made in such a way that closed magnetic field paths are obtained for the relevant fields.
In another embodiment, sheet strip material is used in production of magnetic cores. These cores can be made for example, by rolling a sheet of material into a cylinder or by stacking several sheets together and then cutting the elements which will form the core. It is possible to define at least two directions in the material used to produce the “rolled” cores, for example, the rolling direction (“RD”) and the axial direction (“AD”).
FIGS. 72 and 73 show a sheet of magnetic material and a rolled core respectively. The rolling and the axial direction (RD, AD) are shown in these Figures. As shown in FIG. 73, the rolling direction of a rolled core follows the cylinder's periphery and the axial direction coincides with the cylinder's axis.
Material that has magnetic characteristics that vary depending upon the direction in the material is referred to as anisotropic. FIGS. 74 and 75 show directions defined in a sheet of grain-oriented anisotropic material. Grain oriented (“GO”) material is manufactured by rolling a mass of material between rollers in several steps, together with the heating and cooling of the resulting sheet. During manufacture, the material is coated with an insulation layer, which affects a domain reduction and a corresponding loss reduction in the material. The material's deformation process results in a material where the grains (and consequently the magnetic domains) are oriented mainly in one direction. The magnetic permeability reaches a maximum in this direction. In general, this direction is referred to as the GO direction. The direction orthogonal to the GO direction is referred to as the transverse direction (“TD”). UNISIL and UNISIL-H, for example, are types of magnetic anisotropic materials. In one embodiment, the grain oriented material provides a substantially high percentage of domains available for rotation in the transverse direction. As a result, the material has low losses and allows for improved control of the permeability in the grain oriented direction via the application of a control field in the TD.
Other types of anisotropic material are the amorphous alloys. The common characteristic for all these materials is that one can define an “easy” or “soft” magnetization direction (high permeability) and a “difficult” or “hard” magnetization direction (low permeability). The magnetization in the direction of high permeability is achieved by domain wall motion, while in the low permeability direction, magnetization is achieved by rotation of the domain magnetization in the field direction. The result is a square m-h loop in the high permeability direction and a linear m-h loop in the low permeability direction (where m is the magnetic polarization as a function of the field strength h). Further, in one embodiment, the m-h loop in the transverse direction does not show coercivity and has zero remanence. In this description, the term GO is used when referring to the high permeability direction while the term transverse direction (“TD”) is used when referring to the low permeability direction. These terms will be used not only for grain oriented materials but for any anisotropic material used in the core according to the invention. In one embodiment, the GO direction and the RD are in the same direction. In a further embodiment, the TD and the AD are in the same direction. In another embodiment, the anisotropic material is selected from a group of amorphous alloy consisting of METGLAS Magnetic Alloy 2605SC, METGLAS Magnetic Alloy 2605SA1, METGLAS Magnetic Alloy 2605CO, METGLAS Magnetic Alloy 2714A, METGLAS Magnetic Alloy 2826MB, and Nanokristallin R102. In still a further embodiment, the anisotropic material is selected from a group of amorphous alloys consisting of iron based alloys, cobalt-based alloys, and iron-nickel based alloys.
Although the use of anisotropic material is described, other materials may be used provided that they have a suitable combination of the following characteristics: 1) high peak magnetic polarization and permeability in the RD; 2) low losses; 3) low permeability in the TD; 4) low peak magnetic polarization in the TD; and 5) rotation magnetization in the transverse direction. Table 1 includes a partial list of materials in which the sheet strip may be implemented and some of the characteristics of the materials that are relevant to one or more embodiments of the invention.
Bmax at
1.5 T, 50 Hz
Unisil-H
103-27-P5
105-30-P5
NO 20 grade
Unisil M
140-30- S5
is approx. 6000
140-30-S5,
is approx. 800
AC magnet-
FIG. 76 shows an embodiment of a pipe element in a variable inductance according to the invention. Because this element is made by rolling a sheet of anisotropic material, one can define the rolling direction (RD), the axial direction (AD), the high permeability (GO) direction, and the low permeability (TD) direction. The relative positions of these directions in the element are shown in FIG. 76. The pipe element can have any cross section because the shape of the cross section will simply depend on the shape of the element around which the sheet is rolled. For example, if the sheet is rolled on a parallellepiped with square cross section, the pipe element will have a square cross section. Similarly, a sheet rolled on a pipe with an oval cross section will be formed into a pipe with an oval cross section. In one embodiment, the pipe element is a cylinder.
FIG. 77 shows schematically a part of an embodiment of a device 100 according to the invention. This device 100 comprises a first pipe element 101 and a second pipe element 102, where the elements are connected to one another at both ends by means of magnetic end couplers. For clarity, the magnetic end couplers are not shown in this figure. A first winding 103 is wound around elements 101 and 102 with a winding axis perpendicular to the elements' axes. The magnetic field (Hf, Bf) created by this winding when activated will have a direction along the element's periphery, i.e., an annular direction relative to the elements' axes. A second winding 104 is wound around element 102 with a winding axis parallel to the elements' axes. The magnetic field created by this winding when activated (Hs, Bs) will have a direction parallel to the elements' axes, i.e., an axial direction relative to the elements' axes. In one embodiment, the winding axis of the second winding 104 is coincident the elements' axes. In another embodiment, the elements' axes are not coincident to one another.
If we combine the windings and magnetic fields of FIG. 77 with the rolled material core of FIG. 76, a device 100 according to one embodiment of the invention results. In a version of this embodiment, the magnetic permeability in the direction of a magnetic field (Hf, Bf) introduced by the first winding 103 (i.e., the direction of GO, RD) is significantly higher than the magnetic permeability in the direction of a magnetic field (Hs, Bs) introduced by the second winding 104 (i.e., the direction of TD, AD).
In one embodiment, the first winding 103 constitutes the main winding and the second winding 104 constitutes the control winding. In a version of this embodiment, the main field (Hf, Bf) is generated in the high permeability direction (GO, RD) and the control field (Hs, Bs) is generated in the low permeability direction (TD, AD).
Minimum losses result when anisotropic material is used to provide the device 100 as described with reference to FIGS. 76 and 77. These results are achieved regardless of whether the device 100 is employed in a linear application or a switched application. In a linear application, the device 100 is switched on and remains in a circuit as an inductance. In a switched application, the device 100 is used for connecting and disconnecting another device to a power source.
Low losses allow the device 100 to be employed in high power applications, for example, applications in circuits that can employ transformers ranging from a few hundred kVA to several MVA in size.
As shown in Equation 44) the power handling capacity of the core is dependent on the maximum blocking voltage Ub at high permeability and the maximum magnetizing current Im at the minimum value of the controlled permeability.
Ps=Ub�Im 44)
If the magnetizing current and the blocking voltage are expressed as functions of the magnetic field density Bm, the apparent power Ps can be expressed as:
Where Vj is the volume of the main flux path in the core, μo is the permeability of free space, and μr is the relative permeability of the core. Equation 45) shows that the power handling capacity is related to both the volume of the core and the relative permeability of the core. At very high permeability the magnetizing current is at its lowest level and only a small amount of power is being conducted.
It is clear from Equation 45) that the apparent power Ps per volume unit of the core is related to the relative permeability μr. For two similar cores, where the minimum relative permeability of the first core is half the minimum relative permeability of a second core, the first core's apparent power is twice as large as the second core. Thus, the power handling of a given core volume is limited by the minimum relative permeability of the core volume.
Accordingly, in one embodiment, the volume of the magnetic end couplers is approximately 10–20% of the main core but the magnetic end coupler volume can be further lowered to � or � of that depending on the construction of the core, and the necessary power handling capacity. In one such embodiment, the volume of magnetic end couplers is 5%–10% of the volume of the main core. In yet another embodiment, the volume of the magnetic end couplers is 2.5%–5% of the volume of the main core.
A phenomenological theory of the magnetization curves and hysteresis losses in grain oriented (GO) laminations is described in an article entitled, “Comprehensive Model of Magnetization Curve, Hysteresis Loops, and Losses in Any Direction in Grain-Oriented Fe—Si”, by Fiorillo et al. which published in IEEE Transactions on Magnetics, vol. 38, NO. 3, May 2002 (hereinafter “Fiorillo et al.”). Fiorillo et al. provides theoretical and experimental proof of the fact that the volume that evolves with magnetization in the transverse direction is occupied for magnetization in the rolling direction. Thus, the article demonstrates that it is possible to control permeability in one direction by means of a field in another direction.
Fiorillo et al. also provides a model of the processes in a GO material. It presents, for example, a model that includes magnetization curves, hysteresis loops, and energy losses in any direction in a GO lamination. The model is based on the single crystal approximation and describes that the domains evolve in a complex fashion when a field is applied along the TD. Referring to FIG. 88, a GO sheet comprises a pattern of 180� domain walls basically directed along the RD. The demagnetized state (FIG. 88 a) is characterized by magnetization Js directed along [001] and [00{overscore (1)}]. When a field is applied in the TD (FIG. 88 b), the basic 180� domains transform, through 90� domain wall processes, into a pattern made of bulk domains, having the magnetization directed along [100] and [0{overscore (1)}0] (i.e. making an angle of 45� with respect to the lamination plane). When this new domain structure occupies a fractional sample volume the macroscopic magnetization value is:
J90=Magnetization in TD
Js=Magnetization in RD
v90=Fractional sample volume
The maximum magnetization obtainable at the end of the magnetization process is J90=1.42 Tesla and further increase is obtained by moment rotations of domains.
Fiorillo et al. also shows that the volume of the sample occupied by 180� domains decreases because of the growth of the 90� domains. Thus, permeability or flux conduction for fields applied in the rolling direction can be controlled with a control field and controlled domain displacement in the transverse direction.
The magnetization behavior in the transverse direction in GO steel is described in “Magnetic Domains” by Hubert et al., Springer 2000, pages 416–417 and 532–533. Control of the domain displacement in the transverse direction to control permeability in the rolling direction is most favorable primarily because motions of the 180� walls are avoided when a field is applied perpendicular to the 180� walls. Thus, the main field does not affect the orthogonal control field, in already TD magnetized volumes.
In contrast to GO steel where the magnetization mechanism in GO direction and the TD differ, the magnetization of non-oriented steel consists primarily of 180� domain wall displacements; therefore, the controlled volume is continuously affected by both the main field and the control field in nonoriented steel.
FIG. 78 shows an embodiment of the device 100 according to the invention. The Figure shows first pipe element 101, first winding 103, and the magnetic end couplers 105, 106. The anisotropic characteristic of the magnetic material for the pipe elements has already been described, it consists of the material having the soft magnetization direction (GO) in the rolling direction (RD).
The pipe elements are manufactured by rolling a sheet of GO material. In one embodiment, the GO material is high-grade quality steel with minimum losses, e.g., Cogent's Unisil HM105-30P5.
The permeability of GO steel in the transverse direction is approximately 1–10% of the permeability in the GO direction, depending on the material. As a result, the inductance for a winding which creates a field in the transverse direction is only 1–10% of the inductance in the main winding, which creates a field in the GO direction, provided that both windings have the same number of turns. This inductance ratio allows a high degree of control over the permeability in the direction of the field generated by the main winding. Also, with control flux in the transverse direction, the peak magnetic polarization is approx. 20% lower than in the GO direction. As a result, the magnetic end couplers in the device according to an embodiment of the invention are not saturated by the main flux or by the control flux, and are able to concentrate the control field in the material at all times.
To prevent eddy current losses and secondary closed paths for the control field, in one embodiment, an insulation layer is sandwiched between adjacent layers of sheet material. This layer is applied as a coating on the sheet material. In one embodiment, the insulation material is selected from a group consisting of MAGNITE and MAGNITE-S. However, other insulating material such C-5 and C-6, manufactured by Rembrandtin Lack Ges.m.b.H, and the like may be employed provided they are mechanically strong enough to withstand the production process, and also have enough mechanical strength to prevent electrical short circuits between adjacent layers of foil. Suitability for stress relieving annealing and poured aluminium sealing are also advantageous characteristics for the insulating material. In one embodiment, the insulation material includes organic/inorganic mixed systems that are chromium free. In another embodiment, the insulation material includes a thermally stable organic polymer containing inorganic fillers and pigments.
FIG. 79 is a sectional view of an embodiment of the device 100 according to the invention. In this embodiment, the first pipe element 101 comprises a gap 107 in the element's axial direction located between a first layer and a second layer of the first pipe layer. The main function of gap 107 is to adapt the power handling capacity and volume of material to a specific application. The presence of an air gap in the core's longitudinal direction will cause a reduction in the core's remanence. This will cause a reduction in the harmonic contents of the current in the main winding when the permeability of the core is lowered by means of a current in the control winding. A thin insulation layer is situated in the gap 107 between the two parts of element 101. In a version of this embodiment, the magnetic end couplers are not divided into two parts.
FIGS. 80–87 relate to different embodiments of the magnetic end couplers. In one embodiment, the material used for the magnetic end couplers is anisotropic. In a version of this embodiment, the magnetic end couplers provide a hard magnetization (low permeability) path for the main magnetic field Hf, that is created by the first winding 103. The control field Hs, the field created by the second winding 104 (not shown in FIG. 78), will meet a path with high permeability in the magnetic end couplers and low permeability in the pipe elements.
The magnetic end couplers or control-flux connectors can be manufactured from GO-sheet metal or wires of magnetic material with the control field in the GO direction and the main field in the transverse direction. The wires may be either single wires or stranded wires.
In one embodiment, the magnetic couplers are made of GO-steel to ensure that the end couplers do not get saturated before the pipe elements or cylindrical cores in the TD, but instead, concentrate the control flux through the pipe elements. In another embodiment, the magnetic couplers are made of pure iron.
We will now describe the magnetic field behavior in the end couplers in an embodiment of the device corresponding to FIG. 78. Initially, that is, when the second winding or control winding 104 is not activated, only a very small fraction (approx. 0.04–0.25%) of the main field Hf enters the magnetic end couplers' volume because of the very low permeability in the main field direction (TD) in the magnetic end coupler. The permeability in the main field direction Hf, TD is from 8 to 50 through the end coupler depending on the construction and material used. As a result, the main flux Bf goes in the volume of the pipe elements or cylindrical cores 101, 102. Additionally, the concentration of the main flux allows the main cores' 101, 102 permeability to be adjusted downward to approximately 10.
The control flux-path (Bs in FIGS. 77 and 78) goes up axially within one of the pipe elements' 101, 102 core wall and down within the other element's core wall and is closed by means of magnetic end couplers 105, 106 at each end of the concentric pipe elements 101, 102.
The control flux (B) path has very small air gaps provided by thin insulation sheets 108 between the magnetic end couplers 105, 106 and the circular end areas of the cylindrical cores (FIG. 80). This is important to prevent creation of a closed current path for the transformer action from the first winding 103 through the “winding” made by the first and the second pipe elements 101,102 and the magnetic end couplers 105, 106.
As previously mentioned, the magnetic end couplers according to one embodiment of the invention are made of several sheets of magnetic material (laminations). The embodiment is shown in FIGS. 81–85. FIG. 81 shows the magnetic end coupler 105 of GO sheet steel and the pipe elements 101 and 102 seen from above. Each segment of the end coupler 105 (for example, segments 105 a and 105 b) is tapered from a radially inward end 110 to a radially outward end 112, where the radially inward end 110 is narrower than the radially outward end 112. Directions GO and TD are shown in FIG. 81 as they apply to each segment 105 a, 105 b of the end coupler. A portion of the end coupler 105 on the left and the right sides of FIG. 81 has been removed to show sheet ends 114 of the inner core 102 and the outer core 101. FIG. 82 shows a torus shaped member 116, which when cut into two parts, provides the magnetic end couplers. FIG. 83 shows a cross section of the torus and the relative position of the sheets (e.g., laminations) 105′ of magnetic material. FIGS. 83 and 84 show the GO direction in the magnetic end couplers, which coincides with the direction of the main field. FIG. 85 shows how the size and shape of the magnetic coupler segment 105 a is adjusted to insure that the coupler connects the first pipe element 101 (outer cylindrical core) to the second pipe element 102 (inner cylindrical core) at each end. In FIG. 85 radially inward end 110 is narrower than radially outward end 112.
In another embodiment of the invention, shown in FIG. 86, the same type of segments is made using magnetic wire. Production of end couplers using stranded or single wire magnetic material. The toroidal shape formed by the magnetic material is cut into two halves as indicated by cross section A—A in FIG. 86. FIG. 87 shows how the ends of the magnetic wires provide entry and exit areas for the magnetic field Hf. Each wire provides a path for the magnetic field Hf.
To be able to increase the power handled by the controllable inductive device, the core can be made of laminated sheet strip material. This will also be advantageous in switching where rapid changes of permeability are required.
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Inc.Devices and methods for redistributing magnetic flux density* Cited by examinerClassifications U.S. Classification336/220, 336/222, 336/221International ClassificationG05F1/32, H01F29/14, H01F17/04Cooperative ClassificationH01F2029/143, G05F1/32, H01F29/14, H01F27/306, H01F17/043, H01F27/255, H01F3/10, H01F29/146European ClassificationH01F3/10, H01F29/14B, H01F29/14, G05F1/32Legal EventsDateCodeEventDescriptionMar 15, 2004ASAssignmentOwner name: MAGTECH, NORWAYFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HAUGS, ESPEN;STRAND, FRANK;REEL/FRAME:015069/0798;SIGNING DATES FROM 20040202 TO 20040204Sep 28, 2004ASAssignmentOwner name: MAGTECH AS, NORWAYFree format text: RE-RECORD TO CORRECT THE RECEIVING PARTY S NAME, PREVIOUSLY RECORDED AT REEL 015069, FRAME 0798;ASSIGNORS:HAUGS, ESPEN;STRAND, FRANK;REEL/FRAME:015193/0977;SIGNING DATES FROM 20040202 TO 20040204Oct 7, 2009FPAYFee paymentYear of fee payment: 4Oct 7, 2013FPAYFee paymentYear of fee payment: 8Sep 10, 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