Four-legged coupled inductor

Abstract

The invention relates to a four-leg coupled inductor comprising a four-leg magnetic core with C-shaped sections cooperatively defining three windows. Respective coils or phase windings are wound around each leg, and a portion of two respective phase windings are disposed in each respective window. The magnetic core can be a laminated structure formed of nanocrystalline material. Two air gaps can be defined by each leg. The magnetic core can be supported by a substrate having thermally conductive fins.

Description

Technical Field

[0001] This disclosure relates to an inductor and more specifically to a four-legged coupled inductor. Background Technology

[0002] Traditional single-phase and multi-phase alternating current (AC) power supply circuits typically include an electrical low-pass filter to block high-frequency AC ripple current, or "noise," from the AC output signal, while allowing low-frequency AC current to pass through. High-frequency AC ripple current is typically generated as a result of pulse-width modulation (PWM) switching operation of a semiconductor device. High-frequency AC ripple current can include harmonic noise, which, if not filtered, will cause distortion of the AC output signal. Low-pass filter circuits typically include one or more inductors to provide high impedance to high-frequency noise and low impedance to low-frequency AC current. Inductors typically include a ferromagnetic core with conductive windings wound around it. Summary of the Invention

[0003] According to one embodiment of the present invention, a four-legged coupled inductor includes: a magnetic core having a first leg, a second leg, a third leg, and a fourth leg spaced apart from each other; a first set of inner core segments, including: a first inner core segment extending between and magnetically coupled to a first end of the first leg and a first end of the second leg; a second inner core segment extending between and magnetically coupled to a first end of the second leg and a first end of the third leg; a third inner core segment extending between and magnetically coupled to a first end of the third leg and a first end of the fourth leg; a second set of inner core segments, including: a fourth inner core segment extending between and magnetically coupled to a second end of the first leg and a second end of the second leg; a fifth inner core segment extending between and magnetically coupled to a second end of the second leg and a second end of the third leg; a sixth inner core segment extending between and magnetically coupled to a second end of the third leg and a second end of the fourth leg; and a group of outer core segments. It includes: a first outer core section extending between and magnetically coupled to a first end of a first leg and a first end of a fourth leg; a second outer core section extending between and magnetically coupled to a second end of a first leg and a second end of a fourth leg; a first window defined between the first leg and the second leg; a second window defined between the second leg and the third leg; a third window defined between the third leg and the fourth leg; a first phase winding wound around the first leg, the first phase winding having a portion extending through the first window; a second phase winding wound around the second leg, the second phase winding having a portion extending through the first window and another portion extending through the second window; a third phase winding wound around the third leg, the third phase winding having a portion extending through the second window and another portion extending through the third window; and a fourth phase winding wound around the fourth leg, the fourth phase winding having a portion extending through the third window.

[0004] According to one embodiment of the present invention, the magnetic core is formed of stacked magnetic layers.

[0005] According to one embodiment of the present invention, the magnetic layer is formed of a nanocrystalline material.

[0006] According to one embodiment of the present invention, the four-legged coupled inductor further includes a group of air gaps defined between a respective first end of the first, second, third, and fourth core legs and at least one of a first group of inner core segments and a first outer core segment.

[0007] According to one embodiment of the present invention, the grouped air gaps are a first group of air gaps and also include a second group of air gaps, which are defined between the respective second ends of the first, second, third and fourth core legs and at least one of the second group of inner core segments and the second outer core segment.

[0008] According to one embodiment of the invention, a group of air gaps and a first window, a second window, and a third window cooperate to define a continuous hole through the magnetic core.

[0009] According to one embodiment of the invention, a continuous hole is a first hole, and wherein a second set of air gaps and a first window, a second window and a third window cooperate to define a continuous second hole through the magnetic core.

[0010] According to one embodiment of the invention, the four-legged coupled inductor further includes a corresponding pad disposed in at least one of the first set of air gaps or the second set of air gaps.

[0011] According to one embodiment of the present invention, the corresponding gasket is formed of a thermally conductive ceramic material.

[0012] According to one embodiment of the present invention, the four-legged coupled inductor further includes a substrate having a frame portion, wherein the magnetic core is supported by the frame portion.

[0013] According to one embodiment of the present invention, the substrate further includes a first inner fin extending from the frame portion and through a first window, a second inner fin extending from the frame portion and through a second window, and a third inner fin extending from the frame portion and through a third window.

[0014] According to one embodiment of the invention, the substrate further includes a pair of outer fins disposed on and extending therefrom the opposite ends of the frame portion.

[0015] According to one embodiment of the present invention, a first phase winding is placed between a first outer fin and a first inner fin, a second phase winding is placed between a first inner fin and a second inner fin, a third phase winding is placed between a second inner fin and a third inner fin, and a fourth phase winding is placed between a third inner fin and a second outer fin.

[0016] According to an embodiment of the present invention, a method of forming a four-legged coupled inductor includes: forming a magnetic core having a first leg, a second leg, a third leg, and a fourth leg spaced apart from each other; a first set of inner core segments, comprising: a first inner core segment extending between and magnetically coupled to a first end of the first leg and a first end of the second leg; a second inner core segment extending between and magnetically coupled to a first end of the second leg and a first end of the third leg; a third inner core segment extending between and magnetically coupled to a first end of the third leg and a first end of the fourth leg; a fourth inner core segment extending between and magnetically coupled to a second end of the first leg and a second end of the second leg; a fifth inner core segment extending between and magnetically coupled to a second end of the second leg and a second end of the third leg; a sixth inner core segment extending between and magnetically coupled to a second end of the third leg and a second end of the fourth leg; and a group of outer core segments. It includes: a first outer core section extending between and magnetically coupled to a first end of a first leg and a first end of a fourth leg; a second outer core section extending between and magnetically coupled to a second end of a first leg and a second end of a fourth leg; a first window defined between the first leg and the second leg; a second window defined between the second leg and the third leg; a third window defined between the third leg and the fourth leg; a first phase winding wound around the first leg, a portion of which extends through the first window; a second phase winding wound around the second leg, the second phase winding having a portion extending through the first window and another portion extending through the second window; a third phase winding wound around the third leg, the third phase winding having a portion extending through the second window and another portion extending through the third window; and a fourth phase winding wound around the fourth leg, the fourth phase winding having a portion extending through the third window.

[0017] According to one embodiment of the present invention, the magnetic core is formed of stacked magnetic layers, wherein the magnetic layers are formed of nanocrystalline material.

[0018] According to one embodiment of the present invention, forming the magnetic core further includes: defining a first set of air gaps between the respective first ends of the first leg, the second leg, the third leg and the fourth leg and at least one of the first set of inner core segments and the first set of outer core segments; and defining a second set of air gaps between the respective second ends of the first leg, the second leg, the third leg and the fourth leg and at least one of the second set of inner core segments and the second set of outer core segments.

[0019] According to one embodiment of the present invention, a first set of air gaps and a first window, a second window and a third window cooperate to define a continuous first hole through the magnetic core, and a second set of air gaps and a first window, a second window and a third window cooperate to define a continuous second hole through the magnetic core.

[0020] According to one embodiment of the present invention, the method of forming a four-legged coupled inductor further includes placing a corresponding thermally conductive pad in at least one of a first set of air gaps or a second set of air gaps.

[0021] According to an embodiment of the present invention, the method of forming a four-legged coupled inductor further includes supporting a magnetic core on a substrate having a frame portion, wherein the substrate includes a first inner fin, a second inner fin, and a third inner fin extending from the frame portion, and wherein supporting the magnetic core on the substrate includes: distributing the first inner fin through a first window, distributing the second inner fin through a second window, and distributing the third inner fin through a third window.

[0022] According to one embodiment of the present invention, the substrate further includes a first outer fin and a second outer fin extending from opposite ends of the frame portion, and supporting the magnetic core on the substrate further includes: placing the first outer fin outside the first window and placing the second outer fin outside the third window. Attached Figure Description

[0023] The full and practiceable disclosure of this specification, including its best mode, is set forth in this specification for those skilled in the art, and reference is made to the accompanying drawings, in which: Figure 1 This is a perspective view of a coupled inductor based on the various aspects described in this article.

[0024] Figure 2A This is an isometric front view of the core of the coupled inductor in Figure 2, based on the various aspects described herein.

[0025] Figure 2B Figure 2 is an isometric top view of the core of the coupled inductor, based on the various aspects described in this article.

[0026] Figure 3 This is a perspective view of the windings of the coupled inductor in Figure 2, based on the various aspects described herein.

[0027] Figure 4 This is a perspective view of the substrate of the coupled inductor in Figure 2, based on the various aspects described herein.

[0028] Figure 5 This is a flowchart of a method for forming a four-legged coupled inductor according to another aspect of this disclosure. Detailed Implementation

[0029] This disclosure relates to a coupled inductor. For illustrative purposes, this disclosure will be described with respect to a four-legged coupled inductor, such as one used as a differential-mode filter in a power distribution system (e.g., an aircraft). This disclosure is applicable to a wide variety of inductor devices and power distribution systems and can be used to provide benefits in other industrial, commercial, military, and residential applications. Further non-limiting examples of other vehicles or engines to which this disclosure may relate may include boats, helicopters, automobiles, or other water, air, space, or land vehicles. Industrial, commercial, or residential applications of this disclosure may include, but are not limited to, marine propulsion equipment, wind turbines, hybrid electric machines, or small power plants. However, it will be understood that this disclosure is not limited thereto and can be generalized to non-aircraft applications, such as power distribution requirements in non-aircraft power distribution applications.

[0030] As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as being more preferred or advantageous than other implementations. Furthermore, unless otherwise specifically stated, all aspects described herein should be considered exemplary.

[0031] As used herein, the terms “first,” “second,” and “third,” etc., are used interchangeably to distinguish one component from another and are not intended to indicate the position or importance of individual components. The singular forms “a,” “an,” and “the” include plural references unless the context clearly specifies otherwise. Furthermore, as used herein, the term “group” or “group of” elements can refer to any number of elements, including just one. All directional references (e.g., inside, outside, up, down, radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, upstream, downstream, rear, etc.) are used for identification purposes only to aid the reader’s understanding of this disclosure and do not impose any limitation, particularly regarding the position, orientation, or use of this disclosure.

[0032] The term "connection" (e.g., attachment, coupling, connection, and joining) should be interpreted broadly and may include intermediate components between sets of elements as well as relative movement between elements, unless otherwise stated. Therefore, the term "connection" does not necessarily mean that two elements are directly connected and in a fixed relationship with each other.

[0033] As used herein, the elements “electrical connection” and “electrical coupling” include the transmission or reception of electrical signals to or from such connected or coupled elements. Furthermore, such electrical connections or couplings may include wired or wireless connections, or combinations thereof. In non-limiting examples, connection or disconnection may be selectively configured to provide, enable, disable, etc., an electrical connection between the respective elements. Additionally, while terms such as “voltage,” “current,” and “power” may be used herein, it will be apparent to those skilled in the art that these terms may be associated with each other when describing aspects of a circuit or its operation.

[0034] As used herein, the terms “electrical insulation,” “insulator,” or “insulation” refer to materials exhibiting low electrical conductivity (e.g., less than about 10⁻⁻⁶). 8 Siemens materials per meter (S / m). Unless otherwise stated, as used herein, the term "insulation" refers to electrical insulation, and the term "insulator" refers to an electrical insulator.

[0035] As used herein, the term "conductivity" refers to the property of a material that allows charge or current to flow through it. Also as used herein, the term "electrical conductor" refers to exhibiting a relatively high electrical conductivity (e.g., greater than about 10⁻⁻⁴). 7 Materials with a conductivity of S / m. Unless otherwise stated, as used herein, the term “conductivity” refers to electrical conductivity and the term “conductor” refers to an electrical conductor.

[0036] As used herein, the term "inductance" or "self-inductance" refers to the property of a conductive coil to resist changes in the current flowing through it. Also as used herein, the term "mutual inductance" for two magnetically coupled coils refers to the ratio in which a time-varying magnetic flux generated by one conductive coil is induced in the other. Furthermore, as used herein, the term "equivalent inductance" refers to the total inductance of multiple inductors connected in series or parallel, including their respective self-inductances and any mutual inductances between them.

[0037] An inductor is a passive, two-terminal electrical component typically used to add inductance to a circuit. Inductance is the property of a conductor to resist changes in current and is caused by the magnetic field generated around the conductor when a current passes through it. When the current changes, this magnetic field induces a voltage (called electromotive force or EMF) that resists the change, as described by Lenz's law. An inductor typically consists of insulated wire wound into a coil that stores energy in the generated magnetic field (e.g., as a magnetic flux through a surface). The inductance of a coil can be proportional to the number of turns or windings in the coil. Inductance can also depend on the shape of the coil, the spacing of the windings, and many other factors. Conventional inductors typically consist of a "core" made of a ferromagnetic material (e.g., iron) within the coil. The magnetic field from the coil induces magnetization in the ferromagnetic material, which increases the magnetic flux. As the frequency of the current (e.g., the frequency of AC current) increases, the efficiency of the inductor decreases, for example, due to eddy currents in the core material and the skin effect on the windings.

[0038] Inductors are typically arranged as “coupled inductors” having two or more inductors wound on a common magnetic core. When energized, the inductors are magnetically coupled to each other. Conventional coupled inductor cores are typically formed using a C-shaped magnetic core coupled at its distal end to an I-shaped or another C-shaped magnetic core to define a rectangular closed magnetic core with two legs. Inductors or windings may be wound or coiled around one or two legs of the core to define the coupled inductor. In other conventional arrangements, at least one of the cores may be E-shaped to form a symmetrical closed magnetic system with three legs. Typically, the inductor is wound on the center leg of the E-shaped core, the cross-sectional area of ​​which is twice that of each individual outer leg. In other instances (e.g., three-phase coupled inductor cores), the core legs may be of equal size, and the three legs may support corresponding windings or inductors.

[0039] Coupled inductors are often used in power converters, such as DC-DC converters or DC-AC converters (e.g., three-phase inverters), to transfer energy from one winding to another through a common magnetic core.

[0040] A conventional three-phase inverter is a device that converts a DC input voltage into a three-phase AC output. This DC-AC conversion is typically accomplished using a power semiconductor switching topology. For example, a conventional three-phase pulse-width modulation (PWM) inverter uses a group of six semiconductor switches arranged in three "phase legs" (e.g., one leg for each AC phase) to convert the DC input voltage into a three-phase AC output voltage with precise voltage and frequency control. Typically, the voltage of each phase is controlled by a corresponding PWM signal provided to the respective semiconductor switch. The PWM signal operatively controls the corresponding "on-time" of each semiconductor switch. For example, the duration and sequence of the on-time of each semiconductor switch can be controlled to arrange a 120-degree phase shift between the phase legs, resulting in a balanced three-phase AC voltage output.

[0041] Three-phase inverters are commonly used in conventional power systems, such as to integrate renewable energy sources (such as solar photovoltaic (PV) and wind turbines) into the grid. When three-phase inverters are used to feed unbalanced three-phase loads, three-phase four-wire inverters (e.g., including a neutral line) are typically used to provide a current path for zero-sequence current (e.g., neutral current). Various conventional topologies exist for three-phase four-wire inverters. For example, a conventional three-phase three-legged inverter with a split DC bus capacitor (the so-called "split-link" topology) typically connects the neutral point of the AC load to the midpoint of the DC bus. However, the relatively high capacitance, typically used for unbalanced load conditions (e.g., when power demand is uneven across the three-phase load), adds additional cost and complexity because the neutral current flows through the DC bus capacitor. Another disadvantage is that in some cases the neutral point can be offset and becomes "non-neutral" in practice.

[0042] Another traditional topology is the three-phase four-leg inverter, which adds a fourth leg, called the neutral leg, to accommodate the neutral current. The three-phase four-leg inverter provides improved control for unbalanced loads by providing a stable neutral point and improves DC bus voltage utilization (e.g., up to 15% higher output) compared to split-link topologies. Typically, each phase leg and the neutral leg includes a corresponding pair of semiconductor switching devices coupled together to define a half-bridge, and a corresponding inductor (e.g., a differential-mode inductor). The neutral leg inductor is electrically coupled between the midpoint of the corresponding half-bridge and the AC output neutral point. When the three-phase load is balanced, the neutral leg inductor will conduct only the high-frequency AC ripple current when the low-frequency neutral AC current is close to zero. When the three-phase load is unbalanced, the neutral leg inductor will conduct both the high-frequency AC ripple current and the lower-frequency AC current. The high-frequency AC ripple current will increase core losses in the neutral leg inductor. To attenuate high-frequency AC ripple current (e.g., to reduce neutral inductor core losses), the inductance of the neutral inductor can be increased. For example, a neutral inductor of at least 14 microhenrystals (µH) can be used in a 50 kW, 115VAC, three-phase, four-legged inverter with a 50 kHz PWM switching frequency. Typically, the neutral inductor is selected based on a predetermined trade-off between physical size, maximum flux density (e.g., magnetic field strength per unit area), high-frequency core losses (e.g., energy losses due to hysteresis and eddy currents), and inductance. Achieving this balance can be particularly challenging when available space for the inductor is limited (e.g., in aircraft) and in applications with relatively high ambient temperatures (e.g., above 140 degrees Celsius).

[0043] For example, some conventional four-legged coupled inductors attempt to balance physical size, maximum flux density, high-frequency core losses, and inductance by defining an air gap within the core (e.g., gapped inductors) to control inductance and prevent core saturation. However, because the reluctance of the air gap is greater than that of the core material, flux lines can spread out or “marginalize” at the edges of the air gap, leading to increased eddy currents and core losses. Other conventional inductors, so-called “gapless inductors,” omit the air gap and use materials such as metallic magnetic powder or specific ferrite compositions to achieve high permeability while reducing core losses and maintaining temperature stability. For example, some conventional gapless coupled inductors use ferrite materials to form the core and a relatively small number of winding turns to define the inductor. However, while ferrite materials can provide an advantage in core losses at high frequencies, they typically exhibit low permeability, making it challenging to achieve higher inductance values ​​within a limited physical dimension. Moreover, in gapless inductors, the inductive coupling between phases is limited by the geometry of the core structure, which makes it difficult to arrange power terminals or leads during assembly.

[0044] The aim is to provide a differential-mode inductor filter for three-phase four-wire applications that is monolithic, lightweight, compact, and capable of operating with reduced heat and reduced losses. Aspects disclosed herein may provide a four-legged coupled inductor that overcomes the aforementioned problems while achieving a balance between physical size, maximum flux density, high-frequency core losses, and inductance. Aspects disclosed herein may include a four-legged gapped core having eight C-shaped core segments arranged cooperatively to form four legs defining three windows. Aspects disclosed herein may further provide a core with relatively high inductive coupling between the four legs, wherein the equivalent inductance of each leg is higher than the self-inductance of the corresponding coil wound on the corresponding leg (e.g., 22% higher). Corresponding coils or phase windings may be wound around the respective legs, and portions of two corresponding phase windings may be placed within the respective windows. The magnetic core can be a stacked structure formed using nanocrystalline materials to provide an improved trade-off between saturation flux density (e.g., the maximum flux density that the core material can sustain) and high-frequency core losses (e.g., due to hysteresis and eddy currents) compared to conventional devices with other magnetic materials. The aspect may also include gaps defined between the core and the legs to reduce core losses compared to conventional gapless cores. The aspect may also include two air gaps per leg, such that each of these two air gaps is smaller than a single air gap in each leg to reduce hysteresis and edge flux losses by reducing the thickness of each gap. Non-limiting aspects may also include thermally conductive ceramic pads disposed within the air gaps, and a thermally conductive substrate with thermally conductive fins to reduce heat in the core.

[0045] Reference will now be made in detail to the present aspects of this disclosure, one or more examples of which are illustrated in the accompanying drawings. Detailed descriptions use both numerical and alphabetic names to refer to features in the figures. The same or similar names in the figures and descriptions are used to refer to the same or similar portions of this disclosure.

[0046] Figure 1A coupled inductor 200 is depicted according to a non-limiting aspect. The coupled inductor 200 may include a four-legged magnetic core 400 supported by or coupled to a substrate 300. The substrate 300 may include a frame portion 310 having a group of inner fins 301, 302, 303 extending outwardly therefrom. The frame portion 310 may also include a group of outer fins 304, 305 extending outwardly therefrom. The magnetic core 400 may include a group of core segments 407 arranged to define a group of core legs 401-404. For example, in a non-limiting aspect, the magnetic core may include a first leg 401, a second leg 402, a third leg 403, and a fourth leg 404. The core segments 407 may be C-shaped. The core legs 401-404 may be spaced apart from each other to define a group of windows 461, 462, 463 passing through them. The corresponding coils or phase windings 551-554 may be wound or coiled around the respective core legs 401-404 of the magnetic core 400. Each phase winding 551-554 may include a corresponding set of winding ends 555 for electrical connection to circuit wiring (not shown). Although omitted for clarity of illustration, in a non-limiting aspect, corresponding terminals or connectors (e.g., spade terminals, crimp connectors, solder pads, etc.) may be electrically coupled to the respective winding ends 555.

[0047] In a non-limiting aspect, the grouped windows 461-463 may include a first window 461, a second window 462, and a third window 463. The corresponding phase windings 551-554 may include a first phase winding 551, a second phase winding 552, a third phase winding 553, and a fourth phase winding 554. The first phase winding 551 may be wound around a first leg 401, the second phase winding 552 may be wound around a second leg 402, the third phase winding 553 may be wound around a third leg 403, and the fourth phase winding 554 may be wound around a fourth leg 404. A portion of each phase winding 551-554 may extend through the corresponding windows 461, 462, and 463. Therefore, in a non-limiting aspect, each window 461-463 may have portions of two corresponding phase windings 551-554 extending through it. For example, in a non-limiting aspect, a portion of the first phase winding 551 and a portion of the second phase winding 552 may extend through the first window 461, another portion of the second phase winding 552 and a portion of the third phase winding 553 may extend through the second window 462, and another portion of the third phase winding 553 and a portion of the fourth phase winding 554 may extend through the third window 463.

[0048] The group of inner fins 301-303 may include a first inner fin 301, a second inner fin 302, and a third inner fin 303. Each inner fin 301-303 may extend into a corresponding window 461-463. In a non-limiting aspect, each inner fin 301-303 may be arranged to extend between two corresponding phase windings 551-554. For example, as shown, the first inner fin 301 may be arranged to extend through the first window 461 between the first phase winding 551 and the second phase winding 552, the second inner fin 302 may be arranged to extend through the second window 462 between the second phase winding 552 and the third phase winding 553, and the third inner fin 303 may be arranged to extend through the third window 463 between the third phase winding 553 and the fourth phase winding 554. Therefore, in a non-limiting aspect, each window 461-463 may have a portion of a corresponding inner fin 301-303 extending through it.

[0049] The outer fins 304 and 305 are located outside the magnetic core 400 and do not extend into the windows 461-463. For example, a group of outer fins 304 and 305 may include a first outer fin 304 and a second outer fin 305. The first outer fin 304 and the second outer fin may be located at opposite ends of the substrate 300. In a non-limiting aspect, the first outer fin 304 may be disposed adjacent to the first phase winding 551 and the second outer fin 305 may be disposed adjacent to the third phase winding 553. In such an aspect, each phase winding 551-553 may be disposed between two corresponding fins. For example, the first phase winding 551 may be located between the first outer fin 304 and the first inner fin 301, the second phase winding 552 may be located between the first inner fin 301 and the second inner fin 302, the third phase winding 553 may be located between the second inner fin 302 and the third inner fin 303, and the third phase winding 553 may be located between the third inner fin 303 and the second outer fin 305. Therefore, in a non-limiting aspect, the outer fins 304, 305 do not extend into any of the windows 461-463.

[0050] During operation, phase windings 551-554 are positioned around core legs 401-404. When energized, phase windings 551-554 induce magnetic flux (not shown) into core legs 401-404 and core section 407 of core 400. Heat generated during the operation of phase windings 551-554 can be dissipated from phase windings 551-554 by inner fins 301-303 and outer fins 304-305.

[0051] Figure 2A yes Figure 1 An isometric front view of the magnetic core 400. As shown, the magnetic core 400 may be defined by a group of stacked or magnetic layers 410 arranged to define a stacked structure 409.

[0052] In one non-limiting aspect, the magnetic layer 410 may be formed of ferrite. In some aspects, the magnetic layer 410 may comprise a nanocrystalline alloy, such as, for example, FINEMET. ® Vitreperm ® Nanoperm ® and HiTPerm ® In other non-limiting aspects, the magnetic layer 410 may be formed, for example, of a transition metal, such as iron (Fe), cobalt (Co), or nickel (Ni). In other non-limiting aspects, the magnetic layer 410 may be formed of silicon steel, hiperco... ® Alternatively, it may be formed of a two-phase magnetic material. In other aspects, the magnetic layer 410 may comprise, for example, a crystalline, nanocrystalline, amorphous, soft, or permanent magnetic alloy. In other aspects, the magnetic layer 410 may comprise silicon, iron-cobalt (e.g., hiperco), etc. ® (e.g., superconducting alloys) or iron-nickel (permalloy). In other respects, the magnetic layer 410 may be formed of, for example, amorphous soft magnetic alloys, such as Fe-based alloys, Co-based alloys, Fe-Ni-based alloys, including Metallic alloys. ® and Vitrovac ® The magnetic layer 410 may also include alternative permanent magnet materials, such as neodymium iron boron, samarium cobalt, hexagonal ferrite, alnico or copper nickel iron.

[0053] Figure 2B yes Figure 2A An isometric top view of the magnetic core 400. The grouped core segments 407 may include a first group of inner core segments 431-433, a second group of inner core segments 434-436, and a group of outer core segments 451, 452. In a non-limiting aspect, the first group of inner core segments 431-433, the second group of inner core segments 434-436, and the group of outer core segments 451, 452 may be C-shaped segments. Core legs 401-404, the first group of inner core segments 431-433, and the second group of inner core segments 434-436 may be cooperatively arranged to define a group of windows 461-463 extending through the magnetic core 400. The magnetic core 400 may also define a first group of air gaps 471-473 or a second group of air gaps 474-478, or both.

[0054] The group of core legs 401-404 may include a first leg 401, a second leg 402, a third leg 403, and a fourth leg 404. The core legs 401-404 are spaced apart from each other. For example, in a non-limiting aspect, the core legs 401-404 may be arranged parallel to each other, with the first leg 401 and the fourth leg 404 arranged as outer core legs, and the second leg 402 and the third leg 403 positioned therebetween as intermediate core legs. Each core leg 401-404 includes a corresponding first end 401a-404a, a corresponding opposing second end 401b-404b, and a corresponding intermediate portion 401c-404c extending therebetween. In a non-limiting aspect, the core legs 401-404 may extend between corresponding first air gaps 471-473 and corresponding second air gaps 474-478.

[0055] In a non-limiting aspect, each core leg 401-404 may include corresponding adjacent pairs of leg segments 411-418. For example, in a non-limiting aspect, the first leg 401 may be defined by a first pair of leg segments including the first leg segment 411 and the second leg segment 412, the second leg 402 may be defined by a second pair of leg segments including the third leg segment 413 and the fourth leg segment 414, the third leg 403 may be defined by a third pair of leg segments including the fifth leg segment 415 and the sixth leg segment 416, and the fourth leg 404 may be defined by a fourth pair of leg segments including the seventh leg segment 417 and the eighth leg segment 418. Each leg segment 411-418 may extend from the corresponding first end 411a-418a to the opposite second end 411b-418b of the leg segment, wherein the corresponding intermediate portions 411c-418c of the leg segment extend between the corresponding first end 411a-418a and the corresponding second end 411b-418b. In a non-limiting aspect, each corresponding intermediate portion 411c-418c of the grouped core legs 401-404 may be adjacent to another corresponding leg segment 411c-418c to define adjacent paired leg segments 411-418. In a non-limiting aspect, the adjacent paired leg segments 411-418 may extend between the corresponding first air gap 471-473 and the corresponding second air gap 474-478.

[0056] The first set of inner core segments 431-433 may include a first inner core segment 431, a second inner core segment 432, and a third inner core segment 433. The second set of inner core segments 434-436 may include a fourth inner core segment 434, a fifth inner core segment 435, and a sixth inner core segment 436. Each of the first set of inner core segments 431-433 and the second set of inner core segments 434-436 may be C-shaped. For example, the first set of inner core segments 431-433 may extend from the corresponding first end 431a-433a to the corresponding second end 431b-433b of the inner core segment, wherein the middle portions 431c-433c of the corresponding inner core segments extend between the corresponding first end 431a-433a and the corresponding second end 431b-433b of the inner core segments. Similarly, the second set of inner core segments 434-436 may extend from the corresponding first ends 434a-436a to the corresponding second ends 434b-436b of the inner core segments, wherein the intermediate portions 434c-436c of the corresponding inner core segments extend between the corresponding first ends 434a-436a and the corresponding second ends 434b-436b. Each corresponding inner core segment 431-436 may be magnetically coupled to two adjacent core legs 401-404 and extend between them. In a non-limiting aspect, each first end 431a-436a of the inner core segments may be magnetically coupled to the corresponding leg segments 411-418, and each second end 431b-436b of the inner core segments may be magnetically coupled to another corresponding leg segment 411-418.

[0057] For example, in a non-limiting aspect, the first inner core section 431 may extend from the first end 412a of the second leg section 412 to the first end 413a of the third leg section 413; the second inner core section 432 may extend from the first end 414a of the fourth leg section 414 to the first end 415a of the fifth leg section 415; the third inner core section 433 may extend from the first end 416a of the sixth leg section 416 to the first end 417a of the seventh leg section 417; the fourth inner core section 434 may extend from the second end 412b of the second leg section 412 to the second end 413b of the third leg section 413; the fifth inner core section 435 may extend from the second end 414b of the fourth leg section 414 to the second end 415b of the fifth leg section 415; and the sixth inner core section 436 may extend from the second end 416b of the sixth leg section 416 to the second end 417b of the seventh leg section 417. Each inner core segment of the first group of inner core segments 431-433 can be arranged opposite to a corresponding inner core segment of the second group of inner core segments 434-436. For example, the first inner core segment 431 can be spaced apart from the fourth inner core segment 434, the second inner core segment 432 can be spaced apart from the fifth inner core segment 435, and the third inner core segment 433 can be spaced apart from the sixth inner core segment 436.

[0058] The grouped outer core segments 451, 452 may include a first outer core segment 451 and a second outer core segment 452. The outer core segments 451, 452 may be C-shaped. In a non-limiting aspect, the outer core segments 451, 452 may extend from the respective first ends 451a, 452a of the outer core segments to the respective second ends 451b, 452b of the outer core segments, wherein the intermediate portions 451c, 452c of the respective outer core segments extend between the respective first ends 451a, 452a and the respective second ends 451b, 452b of the outer core segments. The first outer core segment 451 and the second outer core segment 452 may be magnetically coupled to a first leg 401 and a fourth leg 404 (e.g., two outer core legs 401, 404) and extend between them.

[0059] For example, in a non-limiting aspect, the first outer core segment 451 may extend from the first end 411a of the first leg segment 411 to the first end 418a of the eighth leg segment 418, and the second outer core segment 452 may extend from the second end 411b of the first leg segment 411 to the second end 418b of the eighth leg segment 418. In this way, the grouped outer core segments 451, 452, the first leg segment 411, and the eighth leg segment 418 (e.g., the first core leg and the fourth leg 404) may define the periphery of the magnetic core 400. In a non-limiting aspect, the intermediate portion 451c of the first outer core segment 451 may extend correspondingly parallel to the intermediate portions 431c, 432c, and 433c of the first inner core segment 431, the second inner core segment 432, and the third inner core segment 433. In a non-limiting aspect, the intermediate portion 451c of the first outer core segment 451 may correspondingly be adjacent to the intermediate portions 431c, 432c, and 433c of the first inner core segment 431, the second inner core segment 432, and the third inner core segment 433. In a non-limiting aspect, the intermediate portion 452c of the second outer core segment 452 may correspondingly extend parallel to the intermediate portions 434c, 435c, and 436c of the fourth inner core segment 434, the fifth inner core segment 435, and the sixth inner core segment 436. In a non-limiting aspect, the intermediate portion 452c of the second outer core segment 452 may correspondingly be adjacent to the intermediate portions 434c, 435c, and 436c of the fourth inner core segment 434, the fifth inner core segment 435, and the sixth inner core segment 436.

[0060] As in Figure 2BAs shown, the group of windows 461-463 may include a first window 461, a second window 462, and a third window 463. In a non-limiting aspect, each window 461-463 may be defined by corresponding opposing pairs of core legs 401-404 and pairs of opposing inner core segments 431-436. For example, the first window 461 may be defined between the first leg 401 and the second leg 402 (e.g., between the second leg segment 412 and the third leg segment 413), and between the first inner core segment 431 and the fourth inner core segment 434. The second window 462 may be defined between the second leg 402 and the third leg 403 (e.g., between the fourth leg segment 414 and the fifth leg segment 415), and between the second inner core segment 432 and the fifth inner core segment 435. The third window 463 may be defined between the third leg 403 and the fourth leg 404 (e.g., between the sixth leg segment 416 and the seventh leg segment 417), and between the third inner core segment 433 and the sixth inner core segment 436.

[0061] The first set of air gaps 471-474 may include a first air gap 471, a second air gap 472, a third air gap 473, and a fourth air gap 474. In a non-limiting aspect, the first set of air gaps 471-474 may be defined between the corresponding first ends 401a-404a of the core legs 401-404 and the corresponding inner core sections of the first set of inner core sections 431-433 and the first outer core section 451.

[0062] The second set of air gaps 475-478 may include a fifth air gap 475, a sixth air gap 476, a seventh air gap 477, and an eighth air gap 478. In a non-limiting aspect, the second set of air gaps 475-478 may be correspondingly defined between the corresponding second ends 401b-404b of the core legs 401-404 and the corresponding inner core sections and the second outer core section 452 of the second set of inner core sections 434-438.

[0063] For example, in a non-limiting aspect, the first air gap 471 may be defined between the first end 451a of the first outer core section 451 and the first end 411a of the first leg section 411, and between the first end 431a of the first inner core section 431 and the first end 412a of the second leg section 412. The second air gap 472 may be defined between the second end 431b of the first inner core section 431 and the first end 413a of the third leg section 413, and between the first end 432a of the second inner core section 432 and the first end 414a of the fourth leg section 414. The third air gap 473 may be defined between the second end 432b of the second inner core section 432 and the first end 415a of the fifth leg section 415, and between the first end 433a of the third inner core section 433 and the first end 416a of the sixth leg section 416. The fourth air gap 474 may be defined between the second end 433b of the third inner core section 433 and the first end 417a of the seventh leg section 417, and between the second end 451b of the first outer core section 451 and the first end 418a of the eighth leg section 418. The fifth air gap 475 may be defined between the first end 452a of the second outer core section 452 and the second end 411b of the first leg section 411, and between the first end 434a of the fourth inner core section 434 and the second end 412b of the second leg section 412. The sixth air gap 476 may be defined between the second end 434b of the fourth inner core section 434 and the second end 413b of the third leg section 413, and between the first end 435a of the fifth inner core section 435 and the second end 414b of the fourth leg section 414. The seventh air gap 477 may be defined between the second end 435b of the fifth inner core section 435 and the second end 415b of the fifth leg section 415, and between the first end 436a of the sixth inner core section 436 and the second end 416b of the sixth leg section 416. The eighth air gap 478 may be defined between the second end 452b of the second outer core section 452 and the second end 418b of the eighth leg section 418, and between the second end 436b of the sixth inner core section 436 and the second end 417b of the seventh leg section 417.

[0064] In a non-limiting aspect, the first air gap 471, the second air gap 472, the third air gap 473, and the fourth air gap 474 may be fluidly coupled to the first window 461, the second window 462, and the third window 463 to define a continuous first hole 481 through the magnetic core 400. Similarly, in a non-limiting aspect, the fifth air gap 475, the sixth air gap 476, the seventh air gap 477, and the eighth air gap 478 may be fluidly coupled to the first window 461, the second window 462, and the third window 463 to define a continuous second hole 482 extending through the magnetic core 400.

[0065] In a non-limiting aspect, the first set of gaskets 491-494 may be correspondingly placed in the first set of air gaps 471-474. Furthermore, in a non-limiting aspect, the second set of gaskets 495-498 may be correspondingly placed in the second set of air gaps 475-478. For example, the first set of gaskets 491-494 may include a first gasket 491 placed in the first air gap 471, a second gasket 492 placed in the second air gap 472, a third gasket 493 placed in the third air gap 473, and a fourth gasket 494 placed in the fourth air gap 474. In a non-limiting aspect, the second set of gaskets 495-498 may include a fifth gasket 495 placed in the fifth air gap 475, a sixth gasket 496 placed in the sixth air gap 476, a seventh gasket 497 placed in the seventh air gap 477, and an eighth gasket 498 placed in the eighth air gap 478.

[0066] The first set of gaskets 491-494 or the second set of gaskets 495-498, or both, may be arranged to prevent relative movement between the corresponding core segments and core legs. For example, in a non-limiting aspect, the first set of gaskets 491-494 may be coupled to the corresponding first ends 401a-404a of the core legs 401-404 and also coupled to the corresponding inner core segments of the first set of inner core segments 431-433 and the first outer core segment 451. In a non-limiting aspect, the second set of gaskets 495-498 may be coupled to the corresponding second ends 401b-404b of the core legs 401-404 and coupled to the corresponding inner core segments of the second set of inner core segments 434-438 and the second outer core segment 452. In some aspects, the first set of gaskets 491-494 or the second set of gaskets 495-498, or both, may be held in place by frictional engagement. In other respects, the first set of gaskets 491-494 or the second set of gaskets 495-498 or both can be kept in place by an interference fit.

[0067] In a non-limiting aspect, the first set of gaskets 491-494 or the second set of gaskets 495-498, or both, may be thermally conductive. In a non-limiting aspect, the first set of gaskets 491-494 or the second set of gaskets 495-498, or both, may be formed of a ceramic material. For example, in a non-limiting aspect, the ceramic material may include, but is not limited to, alumina (Al2O3), silicon carbide (SiC), silicon dioxide (SiO2), magnesium oxide (MgO), zirconium dioxide (ZrO2), yttrium-stabilized zirconium oxide (YSZ), silicon nitride (Si3N4), aluminum nitride (AlN), boron carbide (B4C), and boron nitride (BN), individually or in various combinations thereof. Additionally, the ceramic material may comprise any glass and glass ceramic, such as borosilicate glass, quartz, aluminosilicate, silicate ceramic, or magnesium silicate, individually or in various combinations thereof. The first set of gaskets 491-494 or the second set of gaskets 495-498, or both, can operatively conduct or transfer heat from the magnetic core 400.

[0068] Figure 3 Non-limiting aspects of the windings, such as a first phase winding 551, are depicted, with corresponding terminals omitted from the respective winding ends 555 for clarity. The first phase winding 551 can be formed as a coil having any number of turns or coils 557 (e.g., nine turns of insulated rectangular magnetic wire, having a height of 0.051 inches by a width of 0.144 inches) or turns to define the coil width “W”. As shown, the first phase winding 551 can be wound into groups of winding layers 561, 562, 563, 564. For example, each coil 557 can be arranged as a group of four concentric layers 561, 562, 563, 564. When arranged in this way, the coils 557 can define a winding depth “D”. For example, in the aspect shown, the coils 557 of the first phase winding 551 comprise four layers: a first winding layer 561, a second winding layer 562, a third winding layer 563, and a fourth winding layer 564. Other aspects are not so limited, and it is envisioned that the first phase winding 551 may include any predetermined number of turns 557 to define or define the coil width W, wherein each turn includes a plurality of concentric winding layers 561, 562, 563, 564 to define any predetermined depth D.

[0069] Figure 4 Non-limiting aspects of the substrate 300 are depicted. The substrate 300 may be formed of a thermally conductive material (such as aluminum). A support portion 310 may define the top surface of the substrate 300 and may be configured to supportively receive the magnetic core 400 thereon. The support portion 310 may extend from a first end 311 to an opposing second end 312.

[0070] The inner fins 301-303 are spaced apart from each other and extend outward from the frame portion 310 in a common direction. The inner fins 301-303 are arranged to operatively extend to the corresponding windows 461-463 of the magnetic core 400 when the magnetic core 400 is placed on the frame portion 310. Figure 1 The frame portion 310 may also include a group of outer fins 304, 305 extending outward therefrom. The outer fins 304-305 are configured to be located outside the magnetic core 400 and not extend into windows 461-463. Figure 1 The outer fins 304 and 305 can be placed on opposite ends of the frame portion 310. For example, the first outer fin 304 can be placed on the first end 311 of the frame portion 310, and the second outer fin 305 can be placed on the second end 312 of the frame portion 310.

[0071] Figure 5 A method 600 for manufacturing a four-legged coupled inductor 200 is described. Although described in relation to a coupled inductor, it will be understood that method 600 can be applied to any inductive device, such as a transformer, without departing from the disclosure herein. Figure 1-4Method 600 is described in relation to the coupled inductor 200, but other aspects are not so limited and method 600 can be implemented in any environment using other elements without departing from the scope of this disclosure.

[0072] Method 600 may begin at 610 by forming a magnetic core 400. The magnetic core 400 may be defined by a group of stacked or magnetic layers 410 arranged to define a stacked structure 409.

[0073] In one non-limiting aspect, the magnetic layer 410 may be formed of ferrite. In some aspects, the magnetic layer 410 may comprise a nanocrystalline material or alloy, such as, for example, FINEMET. ® Vitreperm ® Nanoperm ® and HiTPerm ® In other non-limiting aspects, the magnetic layer 410 may be formed, for example, of a transition metal, such as iron (Fe), cobalt (Co), or nickel (Ni). In other non-limiting aspects, the magnetic layer 410 may be formed of silicon steel, hiperco... ® Alternatively, it may be formed of a two-phase magnetic material. In other aspects, the magnetic layer 410 may comprise, for example, a crystalline, nanocrystalline, amorphous, soft, or permanent magnetic alloy. In other aspects, the magnetic layer 410 may comprise silicon, iron-cobalt (e.g., hiperco), etc. ® (e.g., superconducting alloys) or iron-nickel (permalloy). In other respects, the magnetic layer 410 may be formed of, for example, amorphous soft magnetic alloys, such as Fe-based alloys, Co-based alloys, Fe-Ni-based alloys, including Metallic alloys. ® and Vitrovac ® The magnetic layer 410 may also include alternative permanent magnet materials, such as neodymium iron boron, samarium cobalt, hexagonal ferrite, alnico or copper nickel iron.

[0074] The magnetic core 400 may include a first leg 401, a second leg 402, a third leg 403, and a fourth leg 404 spaced apart from each other. The magnetic core 400 may also include groups of inner core segments 431-436. The inner core segments 431-436 may be C-shaped. The inner core segments 431-436 may include: a first inner core segment 431 extending between and magnetically coupled to the first end 401a of the first leg 401 and the first end 402a of the second leg 402; a second inner core segment 432 extending between and magnetically coupled to the first end 402a of the second leg 402 and the first end 403a of the third leg 403; and a third inner core segment extending between and magnetically coupled to the first end 403a of the third leg 403 and the first end 404a of the fourth leg 404. The core 400 includes an inner core segment 433; a fourth inner core segment 434 extending and magnetically coupled between the second end 401b of the first leg 401 and the second end 402b of the second leg 402; a fifth inner core segment 435 extending and magnetically coupled between the second end 402b of the second leg 402 and the second end 403b of the third leg 403; and a sixth inner core segment 436 extending and magnetically coupled between the second end 403b of the third leg 403 and the second end 404b of the fourth leg 404. The core 400 may also include a group of C-shaped outer core segments 451-452. The outer core segments 451-452 may include: a first outer core segment 451 extending and magnetically coupled between the first end 401a of the first leg 401 and the first end 404a of the fourth leg 404; and a second outer core segment 452 extending and magnetically coupled between the second end 401b of the first leg 401 and the second end 404b of the fourth leg 404. The magnetic core 400 may also include a first window 461 defined between the first leg 401 and the second leg 402, a second window 462 defined between the second leg 402 and the third leg 403, and a third window 463 defined between the third leg 403 and the fourth leg 404.

[0075] In a non-limiting aspect, forming the magnetic core 400 at 610 may further include defining: a first set of air gaps 471-473 defined between the respective first ends 401a-404a of the core legs 401-404 and at least one of the first set of inner core segments 431-433 and the first outer core segment 451; and a second set of air gaps 474-476 defined between the respective second ends 401b-404b of the core legs 401-404 and at least one of the second set of inner core segments 434-436 and the second outer core segment 452.

[0076] In a non-limiting aspect, the first set of air gaps 471-473 and the first window 461, the second window 462 and the third window 463 cooperate to define a continuous first hole 481 through the magnetic core 400, and wherein the second set of air gaps 474-476 and the first window 461, the second window 462 and the third window 463 cooperate to define a continuous second hole 482 through the magnetic core 400.

[0077] Method 600 may include, at 620, winding a first phase winding 551 around a first leg 401, a portion of the first phase winding 551 extending through a first window 461. Method 600 may include, at 622, winding a second phase winding 552 around a second leg 402, having a portion extending through the first window 461 and another portion extending through the second window 462. Method 600 may include, at 624, winding a third phase winding 553 around a third leg 403, having a portion extending through the second window 462 and another portion extending through the third window 463. Method 600 may include, at 626, winding a fourth phase winding 554 around a fourth leg 404, having a portion extending through the third window 463.

[0078] Method 600 may include, at 640, supporting the magnetic core on a frame portion 310 of a thermally conductive substrate 300. In a non-limiting aspect, the substrate 300 may further include a first inner fin 301 extending from the frame portion 310, a second inner fin 302 extending from the frame portion 310, and a third inner fin 303 extending from the frame portion 310. In such an aspect, supporting the magnetic core on the frame portion 310 may include: providing the first inner fin 301 through a first window 461, providing the second inner fin 302 through a second window 462, and providing the third inner fin 303 through a third window 463. In a non-limiting aspect, the substrate may further include a first outer fin 304 and a second outer fin 305 extending from opposite ends of the frame portion 310. In this respect, supporting the magnetic core 400 on the frame portion 310 may also include: placing the first outer fin 304 outside the first window 461 and placing the second outer fin 305 outside the third window 463.

[0079] The order depicted is for illustrative purposes only and is not intended to limit any aspect of this disclosure in any way, as it should be understood that parts of this disclosure and their application can be performed in different logical orders, may include additional or intermediate parts, or parts of the described method may be divided into multiple parts, or parts of the described method may be omitted without diminishing the described method.

[0080] This written description uses examples to disclose aspects of this disclosure, including best practices, and also enables any person skilled in the art to practice aspects of this disclosure, including making and using any apparatus or system and performing any of the included methods. The patentable scope of this disclosure is defined by the claims and may include other examples that would occur to a person skilled in the art. Such other examples are intended to fall within the scope of the claims if they have structural elements that are indistinguishable from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims. Further aspects of this disclosure are provided by the subject matter of the following provisions: A four-legged coupled inductor includes: a magnetic core having a first leg, a second leg, a third leg, and a fourth leg spaced apart from each other; a first set of inner core segments including: a first inner core segment extending between and magnetically coupled to a first end of the first leg and a first end of the second leg; a second inner core segment extending between and magnetically coupled to a first end of the second leg and a first end of the third leg; a third inner core segment extending between and magnetically coupled to a first end of the third leg and a first end of the fourth leg; a second set of inner core segments including: a fourth inner core segment extending between and magnetically coupled to a second end of the first leg and a second end of the second leg; a fifth inner core segment extending between and magnetically coupled to a second end of the second leg and a second end of the third leg; a sixth inner core segment extending between and magnetically coupled to a second end of the third leg and a second end of the fourth leg; and a group of outer core segments including: a first inner core segment extending between and magnetically coupled to a second end of the third leg and a second end of the fourth leg; a second set of inner core segments including: a first inner core segment extending between and magnetically coupled to a second end of the third leg and a second end of the fourth leg; a second set of inner core segments including: a first inner core segment extending between and magnetically coupled to a second end of the third leg and a second end of the fourth leg; and a group of outer core segments including: a first inner core segment extending between and magnetically coupled to a second end of the third leg and a second end of the fourth leg; a second set of inner core segments including: a first inner core segment extending between and magnetically coupled to a second end of the third leg and a second end of the fourth leg; and a second set ... An outer core section extending between and magnetically coupled to the first end of the first leg and the first end of the fourth leg; a second outer core section extending between and magnetically coupled to the second end of the first leg and the second end of the fourth leg; a first window defined between the first leg and the second leg; a second window defined between the second leg and the third leg; a third window defined between the third leg and the fourth leg; a first phase winding wound around the first leg, the first phase winding having a portion extending through the first window; a second phase winding wound around the second leg, the second phase winding having a portion extending through the first window and another portion extending through the second window; a third phase winding wound around the third leg, the third phase winding having a portion extending through the second window and another portion extending through the third window; and a fourth phase winding wound around the fourth leg, the fourth phase winding having a portion extending through the third window.

[0081] The four-legged coupled inductor of any of the foregoing clauses, wherein the magnetic core is formed of stacked magnetic layers.

[0082] A four-legged coupled inductor of any of the foregoing clauses, wherein the magnetic layer is formed of a nanocrystalline material.

[0083] The four-legged coupled inductor of any of the foregoing provisions further includes a group of air gaps defined between the respective first ends of the first, second, third, and fourth core legs and at least one of the first group of inner core segments and the first outer core segment.

[0084] The four-legged coupled inductor of any of the foregoing clauses, wherein the grouped air gaps are a first group of air gaps, and further include a second group of air gaps defined between the respective second ends of the first, second, third and fourth core legs and at least one of the second group of inner core segments and the second outer core segment.

[0085] The four-legged coupled inductor of any of the foregoing provisions, wherein a group of air gaps and a first window, a second window and a third window cooperate to define a continuous hole through the magnetic core.

[0086] The four-legged coupled inductor of any of the foregoing provisions, wherein a continuous hole is the first hole, and wherein a second set of air gaps and a first window, a second window and a third window cooperate to define a continuous second hole through the magnetic core.

[0087] Any of the four-legged coupled inductors of the foregoing clauses further includes a corresponding pad disposed in at least one of the first set of air gaps or the second set of air gaps.

[0088] The four-legged coupled inductor of any of the foregoing clauses, wherein the corresponding pad is formed of thermally conductive ceramic material.

[0089] The four-legged coupled inductor of any of the foregoing provisions also includes a substrate having a frame portion, wherein the magnetic core is supported by the frame portion.

[0090] The four-legged coupled inductor of any of the foregoing provisions, wherein the substrate further includes a first inner fin extending from the frame portion and through a first window, a second inner fin extending from the frame portion and through a second window, and a third inner fin extending from the frame portion and through a third window.

[0091] The four-legged coupled inductor of any of the foregoing provisions, wherein the substrate further includes a pair of outer fins disposed on and extending therefrom the opposite ends of the frame portion.

[0092] The four-legged coupled inductor of any of the foregoing clauses, wherein a first phase winding is disposed between a first outer fin and a first inner fin, a second phase winding is disposed between a first inner fin and a second inner fin, a third phase winding is disposed between a second inner fin and a third inner fin, and a fourth phase winding is disposed between a third inner fin and a second outer fin.

[0093] A method of forming a four-legged coupled inductor includes: forming a magnetic core having a first leg, a second leg, a third leg, and a fourth leg spaced apart from each other; a first set of inner core segments comprising: a first inner core segment extending and magnetically coupled to a first end of the first leg and a first end of the second leg; a second inner core segment extending and magnetically coupled to a first end of the second leg and a first end of the third leg; a third inner core segment extending and magnetically coupled to a first end of the third leg and a first end of the fourth leg; a fourth inner core segment extending and magnetically coupled to a second end of the first leg and a second end of the second leg; a fifth inner core segment extending and magnetically coupled to a second end of the second leg and a second end of the third leg; a sixth inner core segment extending and magnetically coupled to a second end of the third leg and a second end of the fourth leg; and a set of outer core segments comprising: A first outer core section extending between and magnetically coupled to the first end of the first leg and the first end of the fourth leg; a second outer core section extending between and magnetically coupled to the second end of the first leg and the second end of the fourth leg; a first window defined between the first leg and the second leg; a second window defined between the second leg and the third leg; a third window defined between the third leg and the fourth leg; a first phase winding wound around the first leg, a portion of which extends through the first window; a second phase winding wound around the second leg, the second phase winding having a portion extending through the first window and another portion extending through the second window; a third phase winding wound around the third leg, the third phase winding having a portion extending through the second window and another portion extending through the third window; and a fourth phase winding wound around the fourth leg, the third phase winding having a portion extending through the third window.

[0094] The method of any of the foregoing clauses, wherein the magnetic core is formed of stacked magnetic layers, wherein the magnetic layers are formed of nanocrystalline material.

[0095] The method of any of the foregoing clauses, further wherein forming the magnetic core further includes: defining a first set of air gaps between a respective first end of the first leg, the second leg, the third leg, and the fourth leg and at least one of the first set of inner core segments and the first set of outer core segments; and defining a second set of air gaps between a respective second end of the first leg, the second leg, the third leg, and the fourth leg and at least one of the second set of inner core segments and the second set of outer core segments.

[0096] The method of any of the foregoing provisions, wherein the first set of air gaps and the first window, the second window and the third window cooperate to define a continuous first hole through the magnetic core, and wherein the second set of air gaps and the first window, the second window and the third window cooperate to define a continuous second hole through the magnetic core.

[0097] The method of any of the foregoing clauses further includes placing the corresponding thermally conductive pad in at least one of the first set of air gaps or the second set of air gaps.

[0098] The method of any of the foregoing provisions further includes supporting the magnetic core on a substrate having a frame portion, wherein the substrate includes a first inner fin, a second inner fin, and a third inner fin extending from the frame portion, and wherein supporting the magnetic core on the substrate includes: distributing the first inner fin through a first window, distributing the second inner fin through a second window, and distributing the third inner fin through a third window.

[0099] In any of the foregoing methods, the substrate further includes a first outer fin and a second outer fin extending from opposite ends of the frame portion, and wherein supporting the magnetic core on the substrate further includes: placing the first outer fin outside the first window and placing the second outer fin outside the third window.

Claims

1. A four-legged coupled inductor, comprising: Magnetic core, which has The first leg, the second leg, the third leg, and the fourth leg, spaced apart from each other; The first core section includes: A first inner core section extends between and magnetically coupled to the first ends of the first leg and the second leg; The second inner core section extends between the first end of the second leg and the first end of the third leg and is magnetically coupled to them; The third inner core section extends between the first end of the third leg and the first end of the fourth leg and is magnetically coupled to them; The second core section includes: A fourth inner core segment extends between and is magnetically coupled to the second ends of the first leg and the second leg; The fifth inner core section extends between and is magnetically coupled to the second end of the second leg and the second end of the third leg; The sixth inner core section extends between and is magnetically coupled to the second ends of the third leg and the fourth leg; The grouped outer core segments include: A first outer core section extends between and is magnetically coupled to the first end of the first leg and the first end of the fourth leg; The second outer core section extends between and is magnetically coupled to the second ends of the first leg and the fourth leg; A first window defined between the first leg and the second leg; A second window defined between the second leg and the third leg; A third window is defined between the third leg and the fourth leg; A first phase winding is wound around the first leg, the first phase winding having a portion extending through the first window; A second phase winding is wound around the second leg, the second phase winding having a portion extending through the first window and another portion extending through the second window; A third phase winding is wound around the third leg, the third phase winding having a portion extending through the second window and another portion extending through the third window; and A fourth phase winding is wound around the fourth leg, the fourth phase winding having a portion extending through the third window.

2. The four-legged coupled inductor according to claim 1, wherein, The magnetic core is formed from stacked magnetic layers.

3. The four-legged coupled inductor according to claim 2, wherein, The magnetic layer is formed of nanocrystalline material.

4. The four-legged coupled inductor of claim 1 further includes a group of air gaps defined between a respective first end of the first, second, third, and fourth core legs and at least one of the first group of inner core segments and the first outer core segment.

5. The four-legged coupled inductor according to claim 4, wherein, The grouped air gaps are a first group of air gaps and also include a second group of air gaps, which are defined between the respective second ends of the first, second, third and fourth core legs and at least one of the second group of inner core segments and the second outer core segment.

6. The four-legged coupled inductor according to claim 4, wherein, The grouped air gaps and the first window, the second window, and the third window cooperate to define a continuous hole through the magnetic core.

7. The four-legged coupled inductor according to claim 6, wherein, The continuous hole is a first hole, and wherein the second set of air gaps and the first window, the second window and the third window cooperate to define a continuous second hole through the magnetic core.

8. The four-legged coupled inductor of claim 5 further includes a corresponding gasket disposed in at least one of the first set of air gaps or the second set of air gaps.

9. The four-legged coupled inductor according to claim 8, wherein, The corresponding gasket is formed of thermally conductive ceramic material.

10. The four-legged coupled inductor of claim 1, further comprising a substrate having a support portion, wherein, The magnetic core is partially supported by the frame.

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