Abstract: A coil component includes a coil section and an outer package made of magnetic material in which the coil section is embedded. Both ends of the coil section are drawn out as outer electrodes from a first lateral face of the outer package, and the drawn-out sections are bent toward a bottom face of the outer package, and further bent along the bottom face and a second lateral face, then bent toward a cut-out section provided to the top face of the outer package before engaged with the cut-out section. Recesses are provided on the bottom face at places where the outer electrodes overly, and the outer electrodes are bent toward the recesses, respectively. Inside the bent section of each of the outer electrodes, a notch is formed and the notch includes an opening that spreads over the two faces. A vertex portion of the bent section inside the notch is curved.

Abstract: Core bodies which have an alignment structure and allow an alignment during the production of magnetic cores irrespective of production tolerances, in which the production tolerances are compensated. In illustrative embodiments a core body of ferromagnetic material comprises a crossbar having an aspect ratio of length to width greater than 1, and at least one core leg extending laterally away from the crossbar along an extension direction. An alignment recess is formed in a rear surface of the crossbar, which is arranged on a side of the crossbar opposite the core legs. A magnetic core is formed of core bodies, whereby at least one core body is provided with an alignment recess, and the core bodies are aligned relative to one another.

Abstract: A transformer structure includes a winding cylinder which is a hollow tube, at least one limiting ring which is a ring sheet, multiple conductive sheets and at least one winding. The limiting ring is able to slide along the winding cylinder and to sleeve on the outside of the winding cylinder. The conductive sheets are sleeved on the outside of the winding cylinder. Two conductive sheets of the conductive sheets are attached to two end surfaces of the limiting ring while the two conductive sheets and the limiting ring form a winding space. The at least one winding is correspondingly disposed in the winding space. Thereby, the assembly of the transformer is simplified, and the winding area, as well as the voltage ratio of the transformer, is increased.

Abstract: A power management system and method are disclosed. The system can be a high availability power delivery system. The system can be GPS tracked. The system can have multiple batteries, multiple input power sources, and multiple loads. The system can switch between the multiple batteries and the power source to deliver power to the load. The system can ensure there will always be an input power source to power the load.

Abstract: A reactor using a composite magnetic core in which a ferrite core and a soft magnetic metal core are combined. The reactor is composed of a pair of yoke portion magnetic portions composed of ferrite, winding portion core(s) disposed between the opposite planes of the yoke portion cores, and coil(s) winding around the winding portion core(s). The winding portion core(s) is/are formed using a soft magnetic metal core with a substantially constant cross sectional area. Junction portion cores composed of soft magnetic metal powder cores with a tabular shape are disposed at the spaces where the winding portion core(s) face(s) the yoke portion cores, and the area of the part where the junction portion core faces the yoke portion core is made to be 1.3 to 4.0 times that of the section of the winding portion core.

Abstract: A reactor using a composite magnetic core in which a ferrite core and a soft magnetic metal core are combined. The reactor is composed of a pair of yoke portion magnetic portions composed of a ferrite core, winding portion core(s) disposed between the opposite planes of the yoke portion cores, and coil(s) wound around the winding portion core(s). The winding portion core(s) is/are made of a soft magnetic metal core, and the cross sectional area of the part for winding the coil of the winding portion core is substantially constant. When the cross sectional area of the part for winding the coil of the winding portion core is set as S1, and the area of the parts opposite to the yoke portion cores in the winding portion core(s) is set as S2, the area ratio S2/S1 is set to be 1.3 to 4.0.

Abstract: Ferromagnetic cores made from amorphous glasses and methods of forming ferromagnetic cores from metallic glasses are provided. The method forms a magnetic core from a section of a series of concentrically nested ferromagnetic tubes formed of an amorphous metallic material having a Curie-point temperature above room temperature and demonstrating soft ferromagnetic properties, thereby simplifying the manufacturing process and improving the electrical and mechanical performance of the core itself.

Abstract: A coupled inductor includes a ladder magnetic core including two opposing rails extending in a lengthwise direction and joined by a plurality of rungs. The coupled inductor further includes a respective winding wound around each of the plurality of rungs. The plurality of rungs are divided into at least two groups of rungs, and a lengthwise separation distance between adjacent rungs in each group of rungs is less than a lengthwise separation distance between adjacent rungs of different groups of rungs.

Abstract: The present application discloses a magnetic core structure and an electric reactor. The magnetic core structure includes an upper cover plate and a lower cover plate which are arranged oppositely and at least one wrapping post having two ends connected to the upper cover plate and lower cover plate, respectively. A cross-sectional area of the upper cover plate and/or of the lower cover plate is larger than that of the wrapping post. The upper cover plate, the lower cover plate and the wrapping post are made of a magnetic powder core material, an amorphous material, a nanocrystalline material or a silicon steel material. Since the cross-sectional area of the upper cover plate and/or of the lower cover plate is larger than that of the wrapping post, this may bring excellent DC-Bias characteristic to an electric reactor or inductor, and make the electric reactor or inductor have lower magnetic core loss.

Abstract: An amorphous transformer which includes an amorphous core formed of an amorphous material with a lap provided at an upper portion and allowed to stand in substantially a vertical direction while being supported at a core support member, and a coil which is fitted with the amorphous core. The core support member is formed by integrating a core support member for supporting a side surface of the amorphous core and a corner support member for supporting a corner portion of the core. The core support member is provided in substantially a vertical direction along at least one of the side surfaces of the core.

Abstract: A magnetic core includes a first core having a predetermined magnetic permeability and a second core formed of the same material as the first core. The second core forms a closed magnetic circuit together with the first core. The second core is configured to radiate heat through a heat radiating unit. At least one of the first core and the second core is configured to be wound with a coil. The magnetic core includes a third core that is arranged between the first core and the second core and has a lower magnetic permeability than the first core.

Abstract: An integrated circuit has a semiconductor die provided in a first IC layer and an inductor fabricated on a second IC layer. The inductor may have a winding and a magnetic core, which are oriented to conduct magnetic flux in a direction parallel to a surface of a semiconductor die. The semiconductor die may have active circuit components fabricated in a first layer of the die, provided under the inductor layer. The integrated circuit may include a flux conductor provided on a side of the die opposite the first layer. PCB connections to active elements on the semiconductor die may progress through the inductor layer as necessary.

Abstract: A magnetic device is provided. The magnetic device includes a magnetic core and a conductive winding inductively coupled to the magnetic core. The conductive winding includes a first terminal segment, a second terminal segment, and an inductive segment electrically coupled in series therebetween. The first terminal segment includes a current sensing element.

Abstract: A permanent magnet DC inductor is disclosed which includes at least two separate and individual magnetic inductors, each having its own core structure and forming closed individual magnetic paths having at least one magnetic gap. Windings are provided on the magnetic cores, and at least one permanent magnet piece is provided with each inductor. The separate magnetic cores having the at least one magnetic gap are arranged against each other to form external magnetic gaps with the permanent magnet pieces arranged inside the external magnetic gaps on both sides of the at least one magnetic gap.

Abstract: A static apparatus includes an iron core which includes a plurality of magnetic plates stacked in one direction and in which a shaft portion having a main surface and a side surface is formed, and a coil wound around the shaft portion. Slits extending in an axial direction of the shaft portion are formed in at least a surface layer magnetic plate constituting the main surface, of the plurality of magnetic plates. Some of the slits are formed in the main surface, at an end portion close to the side surface, at a predetermined formation density. The formation density of the slits is highest at the predetermined formation density, and is reduced as at least one of a minimum distance from the side surface within the main surface and a distance from the main surface on a side close to the slits in the stacking direction is increased.

Abstract: In a power converting transformer, an I-core has a pair of fixing grooves provided at centers on opposite side surfaces of the I-core in a y-direction in an xyz orthogonal coordinate system, the fixing grooves extending through the I-core in the z-direction, and an E-core has a pair of fixing recess portions provided at x-direction centers of the y-direction opposite end portions of the base portion on a surface opposite from a surface of the base portion facing the I-core. The I-core and the E-core are pressed and fixed to each other by a fixing spring wrapped around the I-core and the E-core through the fixing grooves and the fixing recess portions. An x-direction length of the E-core is shorter than an x-direction length of the I-core, and a y-direction length of the E-core is shorter than or equal to a y-direction distance between the fixing grooves of the I-core.

Abstract: A magnetic device formed with U-shaped core pieces employable in a power converter, and a method of forming the same. In one embodiment, the magnetic device includes a rectilinear core piece formed of a magnetic material, and first and second U-shaped core pieces positioned on the rectilinear core piece. The magnetic device also includes first and second conductive windings formed about the first and second U-shaped core pieces, respectively.

Abstract: An inductive component has a winding and a core that includes a plurality of core areas that contain different magnetic materials.

Abstract: An M-winding coupled inductor includes a first end magnetic element, a second end magnetic element, M connecting magnetic elements, and M windings. M is an integer greater than one. Each connecting magnetic element is disposed between and connects the first and second end magnetic elements. Each winding is wound at least partially around a respective one of the M connecting magnetic elements. The coupled inductor further includes at least one top magnetic element adjacent to and extending at least partially over at least two of the M connecting magnetic elements to provide a magnetic flux path between the first and second end magnetic elements. The inductor may be included in an M-phase power supply, and the power supply may at least partially power a computer processor.

Abstract: An M phase coupled inductor includes a magnetic core including a first end magnetic element, a second end magnetic element, and M legs disposed between and connecting the first and second end magnetic elements. M is an integer greater than one. The coupled inductor further includes M windings, where each winding has a substantially rectangular cross section. Each one of the M windings is at least partially wound about a respective leg.

Abstract: There are provided a core and a coil component including the same. The core includes core pieces coupled to each other, each of the core pieces including: a plurality of legs; a connection part connecting one ends of the legs to each other; and at least one contact part formed at a distal end of at least one of the legs in a manner in which a cross-sectional area of the leg may be decreased.

Abstract: A rectifier transformer including at least one secondary with windings, one pair of magnetic transductors per winding, one of the transductors having one or more first busbars and the other having one or more second busbars. All of the busbars of the pair of transductors are connected to the same winding. The or each first or second, busbar is connected to a single positive or negative, terminal (2w+) designed to be connected to a positive or negative, arm of the rectifier. All of the busbars of the pair of magnetic transductors form one or more groups that are encircled by at least one magnetic toroid and that comprise at least one first busbar and at least one second busbar, so that, when the terminals are short-circuited, the busbars of a group pass currents of opposite directions such that the sum of the currents in one direction is equal to the sum of the currents in the other direction.

Abstract: There is to provide a coil part capable of reducing the number of fastening means such as screws and so on required when attaching it to a substrate. A coil part includes a transformer unit and a reactor unit, wherein the transformer unit includes: a primary winding part formed by winding a flat wire around a primary side hollow part; secondary winding parts, the secondary winding part being formed by winding a flat wire around a secondary side hollow part communicating with the primary side hollow part, arranged in pairs in a state of facing one side and another side of the primary winding part respectively; and a first core inserted into the primary side hollow part and the secondary side hollow part, and the reactor unit includes: a reactor winding part formed by extending one terminal side of the flat wire constituting the secondary winding part and winding the flat wire around a reactor side hollow part; and a second core inserted into the reactor side hollow part.

Abstract: A “Y”-shaped transformer includes a “Y” shaped magnetic core that includes a top portion and a bottom portion. The top portion and the bottom portion both include a plurality of “Y”-shaped laminates stacked on top of one another and bent to form a plurality of core limbs. A plurality of input windings are wound around each of the plurality of core limbs. A plurality of output windings wound are wound around each of the plurality of core limbs.

Abstract: A transformer includes a bobbin, at least one primary winding coil, at least one secondary winding coil, and a magnetic core assembly. The bobbin includes a main body, plural extension structures, and plural pin groups. The main body includes a channel, plural winding sections, a first connecting seat, and a second connecting seat. The plural extension structures are connected with the first connecting seat and the second connecting seat, respectively. In addition, each of the plural extension structures has a notch and a stepped structure, and the stepped structure comprises plural stepped parts. Each of the primary winding coil and the secondary winding coil includes plural outlet terminals. The plural outlet terminals of the secondary winding coil are respectively disposed on the plural stepped parts of the stepped structure and fixed on the pin group which is disposed on one of the extension structures.

Abstract: Disclosed herein is a pulse transformer that includes a drum core having a winding core portion and first and second flange portions, a plate core connected to the first and second flange portions, and a plurality of wires that are wound around the winding core portion. The first and second flange portions and the plate core are ground such that an inductance of the pulse transformer is 350 ?H or more when a bias current of 8 mA is applied to the wires.

Abstract: An inductive coupler assembly for use in a downhole environment and related methods are described. An example indicative coupler assembly includes a first inductive coupler having first and second magnetically coupled coils and a second inductive coupler having third and fourth magnetically coupled coils. The first and third coils are coupled to a first pair of signal lines and the second and fourth coils are coupled to a second pair of signal lines. The first inductive coupler is to magnetically convey a differential communications signal between the first and second pairs of signal lines, and the second inductive coupler is to magnetically convey a common mode power signal between the first and second pairs of signal lines.

Abstract: The disclosure relates to an integral inductor arrangement with at least three magnetic loops arranged side by side to each other in a row and at least one winding associated with each of the magnetic loops. The magnetic loops are formed by individual core elements, each of which being part of one of the magnetic loops, and shared core elements, each of which being part of two adjacent of the magnetic loops. The shared core elements are separated from the individual core elements by magnetic gaps and each of the at least one winding is arranged around one of the individual core elements. The disclosure further relates to a use of such integral inductor arrangement within a 3-phase AC-filter for a power inverter for feeding electrical power into a power grid.

Abstract: A planar closed-magnetic-loop inductor and a method of fabricating the inductor are described. The inductor includes a first material comprising a cross-sectional shape including at least four segments, at least one of the at least four segments including a first edge and a second edge on opposite sides of an axial line through the at least one of the at least four segments. The first edge and the second edge are not parallel.

Abstract: There are provided a magnetic composition including a glass component capable of not reacting with a ferrite grain but being uniformly distributed only in a grain boundary, instead of using an existing glass component, thereby achieving improved permeability, specific resistance and high frequency specific resistance, and a multilayer electronic component manufactured by using the same.

Abstract: A magnetic core is provided. The magnetic core includes a magnetic base and a magnetic plate. The magnetic base includes a first U-core, a second U-core, and a spacing member. The first U-core has a relatively high magnetic permeability, and includes a first surface having a first winding channel defined therein. The second U-core has a relatively high magnetic permeability, and includes a second surface having a second winding channel defined therein. The first and second surfaces are substantially coplanar with one another. The spacing member is connected to the first and second U-cores such that a gap having a relatively low magnetic permeability is formed between the first and second U-cores. The magnetic plate is coupled to the magnetic base such that the magnetic plate substantially covers the first and second surfaces.

Abstract: In a hand tool device having at least one charging coil provided for transmitting energy, the charging coil includes a coil core having at least two core segments which are movable relative to each other.

Abstract: A transformer has two magnetic cores, at least one primary winding unit mounted in the magnetic cores, at least one secondary winding unit mounted in the magnetic cores and two rectifying circuit boards externally mounted beside the magnetic cores. An AC voltage output from the secondary winding unit is transmitted to and rectified by the rectifying circuit board. Therefore, the size of the transformer is compact, and heat energy generated by electronic elements mounted on the rectifying circuit board is effectively dissipated to maintain normal operation of the transformer. Further, since the transmission path from the secondary winding unit to the rectifying circuit board is short, energy loss is reasonably reduced when the transformer is operated under a high frequency situation or a larger current mode.

Abstract: A small reactor capable of appropriately measuring the temperature of a coil is provided. The reactor includes a coil 2 including a pair of coil elements 2a and 2b and a magnetic core including a pair of inner core portions 31 disposed in the respective coil elements 2a and 2b and outer core portions that connect the inner core portions 31 to form a closed magnetic circuit. Each of the coil elements 2a and 2b has an end face shape having a rounded corner portion 21, which is a corner portion of a rectangle that is rounded. A temperature sensor 7 is disposed in a trapezoidal space between the rounded corner portions 21 of the coil elements 2a and 2b that face each other. The temperature sensor 7 is pressed so as to contact the rounded corner portions 21 by the sensor holder portion 54 provided on an insulator, and is capable of appropriately measuring the temperature of the coil 2.

Abstract: The present invention relates to a planar transformer, the transformer including a core provided to induce formation of a magnetic field, a bobbin coupled to a core, at least one primary winding interposed between the core and the bobbin to supply a power signal, a first insulation unit provided to the at least one primary winding to insulate the at least one primary winding, at least one secondary winding provided to the first insulation unit and insulated by the first insulation unit to transform the power signal, and a second insulation unit provided to the at least one secondary winding to insulate the at least one secondary winding.

Abstract: Described herein are improved configurations for a wireless power transfer. Described are methods and designs to reduce and manage heating and heat dissipation in resonator structures. Configuration and orientation of magnetic material as well as heat sinking material with respect to the dipole moment of the resonator is used to reduce and control thermal properties of the resonator structure and reduce the effects of heating on the performance of wireless power transfer.

Abstract: An inductor is provided including a multilayer body in which a plurality of magnetic layers containing a ferrite are laminated. A coil part including a plurality of conductive patterns is disposed in the multilayer body. External electrodes are electrically connected to the coil part. The ferrite may contain iron (Fe), manganese (Mn), nickel (Ni), zinc (Zn), and vanadium (V), and the ferrite may contain 40 to 55 mol % of iron (Fe) calculated as iron oxide (Fe2O3), 5 to 20 mol % of nickel (Ni) calculated as nickel oxide (NiO), 15 to 25 mol % of zinc (Zn) calculated as zinc oxide (ZnO), 15 to 30 mol % of manganese (Mn) calculated as manganese oxide (MnO), and 1 to 4 mol % of vanadium (V) calculated as vanadium oxide (V2O5).

Abstract: A transformer device is disclosed in which a transformer module includes a first transformer unit disposed on a PCB and having a plurality of first pins and a plurality of second pins, and a second transformer unit disposed on the PCB and adjacent to the first transformer unit. The second transformer has a plurality of third pins and a plurality of fourth pins. First to fourth conductive lines are disposed on the PCB, and configured to electrically connect to the plurality of first to fourth pins, respectively. The plurality of first and third pins are located on a first side of the transformer module, the plurality of second and fourth pins are located on a second side opposite to the first side, and the plurality of first pins are adjacent to the plurality of third pins.

Abstract: Provided are a reactor which can perform step-up/step-down operations and soft switching with a small size and a smaller leakage inductance, and a method of adjusting a leakage inductance of the reactor. A reactor 1A includes a magnetic core 10A having a pair of inner core portions and forming a closed magnetic path, a main coil 11A having main coil elements 11a and 11b, and a sub-coil 12A having sub-coil elements 12a and 12b. The coil elements 11a and 12a are concentrically layered over one of the inner coil portions, and the coil elements 11b and 12b are concentrically layered over the other inner coil portion. One end portion of a wire 11w of the main coil 11A and one end portion of a wire 12w of the sub-coil 12A are joined to each other. A spacing between adjacent turns constituting the sub-coil element 12a (12b) is wider than that between adjacent turns constituting the main coil element 11a (11b). Thus, the reactor 1A has a smaller leakage inductance.

Abstract: A layer structure for producing a planar insulation laminate, including the following sequence of planar individual layers arranged one on the other: a B-stage resin, a glass fabric, a core layer made of polyester film, a glass fabric, and a B-stage resin. In the hardened state, an insulation material produced therefrom is suitable, for example, to be used as an insulation barrier between a low-voltage winding and a high-voltage winding of a transformer winding.

Abstract: A coil component comprises: a coil bobbin, which has a coil-winding section in an outer circumferential portion so that a coil is to be wound on the coil-winding section, and which has a through-hole in a central portion thereof; a first core and a second core, which have a plurality of magnetic legs respectively, wherein a certain leg of the plurality of the magnetic legs of the first core and a certain leg of the plurality of the magnetic legs of the second core are inserted into the through-hole of the coil bobbin to face each other with a predetermined gap, and wherein facing surfaces of the certain legs of the magnetic legs are fixed by an adhesive; and a protective cover, which is positioned between the coil bobbin and the certain legs to suppress the adhesive from being attached to the coil bobbin.

Abstract: The object of the invention is an inductive component equipped with a liquid cooling and a method for manufacturing an inductive component. The inductive component comprises at least a core (2) assembled from separate structural elements (8, 8a, 8b), a winding (5), and connection means (7) as well as ducts (9) integrated into the core (2) for the purpose of liquid cooling. Each structural element (8, 8a, 8b) comprises an aperture (9a, 13, 18) made in the manufacturing phase of the structural element (8, 8a, 8b), which aperture extends through the structural element and is a short part of the duct (9) intended for the purpose of liquid cooling.

Abstract: An inductive element including a magnetic core with a section received in a central opening defined in each of the layers in a multilayer circuit board. A primary winding, an auxiliary winding, and a secondary winding are each realized in conductive coils located on a plurality of layers in the circuit board. The secondary winding is separated from the other windings by a relatively-thick dielectric layer. Other dielectric layers separate each of the layers with the coils. EMI shields are provided on other layers. The coils are located in a central region of each layer so as to provide an adequate safety margin from the side edges of the inductive element.

Abstract: When an outer core that is to be mounted on a reactor is seen in plan, the outer core is a compact that has a plan-view shape in which a side of the outer core that is opposite to a facing side of the outer core, which faces the inner cores, has a smaller dimension in a width direction, which is parallel to a facing surface, than the facing side of the outer core. A method of manufacturing such an outer core includes a preparing step and a compacting step. In the preparing step, coated soft magnetic powder including multiple coated soft magnetic particles formed by coating soft magnetic particles with insulating coated films is prepared as raw-material powder of the outer core.

Abstract: A reactor includes: a molded coil including two coils integrally molded with resin; and two U-shaped cores each having core insertion portions inserted in the coils in a coil axial direction, and the cores being joined in a track-like form by interposing gap elements between them to form a core assembly. The molded coil has a substantially hexahedral shape, each of the cores includes a core outer portion joining the core insertion portions, a resin layer made of magnetic-metal containing resin consisting of binder resin and magnetic metal powder mixed therein is formed on outer surfaces of the core outer portions, the molded coil includes a fastening retaining part for holding and fixing the reactor to a cabinet with a fastening member so that the cabinet supports the reactor, and the molded coil is held apart from the cabinet by the fastening member and the fastening-member retaining part.

Abstract: The embodiment relates to a transformer. A transformer according to an aspect includes: a first coil assembly including a first core, a first bobbin coupled to the first core, and a first coil provided on the first bobbin; and a second coil assembly coupled to the first coil assembly, and including a second core, a second bobbin coupled to the second core, and a second coil provided on the second bobbin.

Abstract: A reactor 1? includes a coil 2 formed by winding a wire 2w, a magnetic core 3 that is disposed inside and outside of the coil 2 and forms a closed magnetic circuit, and a case 4 that has an opening portion and a bottom surface 40 that opposes the opening portion and that houses an assembly 10 of the coil 2 and the magnetic core 3. At least the opening portion of the case 4 side of the magnetic core 3 is formed of a molded solid body that contains magnetic powder and resin. A surface layer 5, which prevents the magnetic powder from rusting, is provided on a surface of the magnetic core 3 on the opening portion of the case 4 side. The surface layer 5 has a resin portion formed of resin similar to the resin contained in the magnetic core 3. The resin portion is formed so as to be continuous with the resin contained in the magnetic core 3 without an interface formed therebetween.

Abstract: An auxiliary core portion and a main core portion, including a magnet if the magnet is attached, are covered by a resin film or an elastomer film and fixed as a single assembly. In this state, a coil is attached to the assembly and a side core portion is assembled to the assembly. The auxiliary core portion and the main core portion, including the magnet if it is attached, can be supplied, as the single assembly, to an automated assembly line for ignition coils. It is not necessary to position such components on the assembly line. Thus, the workability of the automated assembly can be enhanced.

Abstract: A coil component comprising a first split magnetic core and a second split magnetic core, each having an outer core leg, an inner core leg and a back yoke connecting the outer core leg and the inner core leg, and a coil block mounted to the inner core leg, wherein the outer core leg has a sectional area smaller than a sectional area of the inner core leg, a density of magnetic body in the outer core leg is different from a density of the magnetic body in any of the inner core leg and the back yoke, and the first split magnetic core and the second split magnetic core are butted against each other to form a magnetic core of a closed magnetic circuit.

Abstract: The device and manufacturing method for a Direct Current (DC) filter inductor are disclosed. The device comprises a magnetic core, at least one first winding and at least one second winding. The magnetic core has at least one air gap. The first winding and the second winding are connected to each other in parallel that having a mutual inductance, and are wrapped around the magnetic core respectively. A difference between a first inductance of the first winding and the mutual inductance is smaller than a difference between a second inductance of the second winding and the mutual inductance. A Direct Current (DC) resistance of the first winding is larger than a DC resistance of the second winding. The first winding is closer to the air gap compared to the second winding.